Conjugated oligoyne-bridged [60]fullerene molecular dumbbells: Syntheses and thermal and morphological properties

pubs.acs.org/joc

Conjugated Oligoyne-Bridged [60]Fullerene Molecular Dumbbells:

Syntheses and Thermal and Morphological Properties

Ningzhang Zhou and Yuming Zhao*

Department of Chemistry, Memorial University of Newfoundland, St. John’s, Newfoundland,

Canada A1B 3X7

yuming@mun.ca

Received November 12, 2009

A series of linear and star-shaped π-conjugated oligomer hybrids (2-5) composed of an oligoyne

core, ranging from 1,3-butadiyne to 1,3,5,7,9,11-dodecahexayne, and fullerenyl end-capping groups

has been synthesized and studied. The molecular structures of these fullerene-oligoyne hybrids were

assembled through three key reactions: Pd-catalyzed cross-coupling, Cu-catalyzed oxidative homo-

coupling, and an in situ alkynylation reaction on [60]fullerene. The properties of these compounds

were investigated by UV-vis spectroscopy, differential scanning calorimetry (DSC), and atomic

force microscopy (AFM) with the purpose of understanding the thermal reactivity arising from the

oligoyne moieties as well as the morphological properties on surface. Our study shows that these

fullerene-oligoyne hybrids tend to aggregate in different morphologies, including nanospheres,

nanoflakes, and continuous thin films, while the morphological properties appear to be subject to the

influence of molecular factors such as oligomer chain length, solubilizing alkylphenyl groups, and the

thermal reactivity of the oligoyne unit. The correlation between molecular property and interfacial

aggregation behavior evinced by these fullerene-oligoyne hybrids suggests a viable approach to exert

bottom-up control over the structures and properties of fullerene based nanomaterials.

Introduction

allotropes, such as buckminster [60]fullerene, carbon nano-

tubes (CNTs), and carbynes (i.e., one-dimensional sp carbon

polymers), have not only promoted extensive studies on the

fundamental properties of nanostructured carbons at var-

ious levels but also provided material scientists with the brick

and mortar to fabricate new advanced molecular devices

with enhanced performance and function.^1-9In recent years,

there has been a growing interest in [60]fullerene (C₆₀)

containing composite materials^10,11because C₆₀and its

Carbon-based nanomaterials are envisioned to play an

important role in next generation electronic and optoelec-

tronic technologies.¹Over the past two decades, the discov-

ery and characterization of a number of appealing carbon

(1) Carbon Nanomaterials; Gogotsi, Y., Ed.; CRC Press: Boca Raton, FL,

2006.

1498 J. Org. Chem. 2010, 75, 1498–1516

Published on Web 02/08/2010

DOI: 10.1021/jo9021748

r

2010 American Chemical Society

Zhou and Zhao

JOCArticle

derivatives are the most commonly employed molecular

building components in the formation of bulk heterojunc-

tions (BHJs) with conducting polymers, which leads the way

to the quest for high-performance polymer solar cells.^12-14

Efficiency of the BHJ solar cell has been steadily improved in

the recent literature, boding well for a potential solution to

the challenge of cost-effectively harnessing solar energy.^12,15-19

However, continued and synergistic efforts to optimize both

the materials and the device structure are still needed before

this technology becomes commercially viable.

SCHEME 1. Graphitization of Bisfullerene-Oligoyne Dumb-

bells 1a via Alkyne Cross-Linking Reactions

It has been demonstrated that the nanomorphology of the

solid thin film in a BHJ solar cell plays a vital role in dictating

the device performance.^12,20-22In the ideal case, acceptors

(C₆₀derivatives) and donors (conjugated polymers) should

form a bicontinuous, microphase separate network to ensure

efficient exciton diffusion. The morphological properties of

C₆₀-polymer blends are related to numerous factors, ranging

from molecular properties (e.g., the structure and solubility/

miscibility of C₆₀derivatives and polymers^20,23) to postproduc-

tion treatment methods (e.g., electrical treatment²⁴and thermal

annealing^25,26). To better understand these complicated issues

as well as to establish structure-property relationship for

guiding rational design and fine-tuning, the synthesis and

characterization of new C₆₀-containing molecular systems are

crucial and indispensable.

In this paper, we report our recent investigations on a

series of conjugated oligoyne-bridged multifullerene mole-

cular ensembles. Particular emphasis has been placed on

dumbbell-shaped bisfullerene-oligoyne hybrids like motif

1a illustrated in Scheme 1. Various dumbbell-shaped C₆₀-

oligomer-C₆₀molecular architectures have drawn consider-

able attention in the fields of photoinduced energy/electron

transfer, organic photovoltaics, organic nonlinear optics,

and molecular machinery.^27-32In the literature, arylene-based

conjugated oligomers such as oligo(phenylene ethynylene)s,^31,33,34

oligo(phenylene vinylene)s,^30,35and oligothiophenes^27,36have

been conveniently employed as the π-bridges to assemble

C₆₀-π-C₆₀dumbbells, owing to their rich electronic and

photonic characteristics as well as satisfactory compatibility

with diverse synthetic and processing conditions. Fullerene

dumbbells bearing conjugated oligoyne π-bridges,^37-41how-

ever, have been scarcely exploited in device fabrications,

primarily due to the conspicuous synthetic challenge and

chemical instability of the oligoyne species.^7,8Conjugated

oligoynes are the substructure of an appealing carbon allo-

trope, namely carbyne.^42-44Aside from the fundamentally

(2) Hirsch, A.; Brettreich, M. Fullerenes: Chemistry and Reactions; Wiley-

VCH: Weinheim, 2005.

(3) Carbon Nanotubes: Science and Applications; Meyyappan, M., Ed.;

CRC Press: Boca Raton, FL, 2005.

(4) Hirsch, A.; Vostrowsky, O. Functional Organic Materials: Syntheses,

Strategies and Applications; Wiley-VCH: New York, 2007; pp 3-57.

(5) Organic Molecular Solids: Properties and Applications; Jones, W., Ed.;

CRC Press: Boca Raton, FL, 1997.

(6) Carbon Nanotubes; Endo, M., Iijima, S., Dresselhaus, M. S., Eds.;

Elsevier Science, Inc.: New York, 1996.

(7) Polyynes: Synthesis, Properties and Applications; Cataldo, F., Ed.;

CRC Press: Boca Raton, FL, 2006.

(8) Carbyne and Carbynoid Structures; Heimann, R. B., Evsyukov, S. E.,

Kavan, L., Eds.; Kluwer Academic Publishers: Norwell, MA, 1999.

(9) Smith, P. P. K.; Buseck, P. R. Science 1982, 216, 984–986.

(10) Dai, L.; Mau, A. W. H. Adv. Mater. 2001, 13, 899–913.

(11) Wang, C.; Guo, Z.-X.; Fu, S.; Wu, W.; Zhu, D. Prog. Polym. Sci.

2004, 29, 1079–1141.

ꢀ

(12) Thompson, B. C.; Frechet, J. M. J. Angew. Chem., Int. Ed. 2008, 47,

58–77.

(13) Gunes, S.; Neugebauer, H.; Sariciftci, N. S. Chem. Rev. 2007, 107,

1324–1338.

€

(14) Brabec, C. J.; Sariciftci, N. S.; Hummelen, J. C. Adv. Funct. Mater.

2001, 11, 15–26.

(15) Ross, R. B.; Cardona, C. M.; Guldi, D. M.; Sankaranarayanan, S.

G.; Reese, M. O.; Kopidakis, N.; Peet, J.; Walker, B.; Bazan, G. C.; Keuren,

E. V.; Holloway, B. C.; Drees, M. Nat. Mater. 2009, 8, 208–212.

(27) van Hal, P. A.; Knol, J.; Langeveld-Voss, B. M. W.; Meskers, S. C. J.;

Hummelen, J. C.; Janssen, R. A. J. J. Phys. Chem. A 2000, 104, 5974–5988.

ꢀ

(28) Sanchez, L.; Herranz, M. A.; Martı

´

n, N. J. Mater. Chem. 2005, 15,

1409–1421.

ꢁ ꢀ

(16) Wong, W.-Y.; Wang, X.-Z.; He, Z.; Djurisic, A. B.; Yip, C.-T.;

(29) Roncali, J. Chem. Soc. Rev. 2005, 34, 483–495.

(30) Langa, F.; Gomez-Escalonilla, M. J.; Rueff, J.-M.; Duarte, T. M. F.;

ꢂ

Nierengarten, J.-F.; Palermo, V.; Samori, P.; Rio, Y.; Accorsi, G.; Armaroli,

Cheung, K.-Y.; Wang, H.; Mak, C. S. K.; Chan, W.-K. Nat. Mater. 2007, 6,

521–527.

(17) Peet, J.; Kim, J. Y.; Coates, N. E.; Ma, W. L.; Moses, D.; Heeger, A.

J.; Bazan, G. C. Nat. Mater. 2007, 6, 497–500.

N. Chem.-Eur. J. 2005, 11, 4405–4415.

(31) Zhao, Y.; Shirai, Y.; Slepkov, A. D.; Cheng, L.; Alemany, L. B.;

Sasaki, T.; Hegmann, F. A.; Tour, J. M. Chem.-Eur. J. 2005, 11, 3643–3658.

(32) Shirai, Y.; Morin, J.-F.; Sasaki, T.; Guerrero, J. M.; Tour, J. M.

Chem. Soc. Rev. 2006, 35, 1043–1055.

€

(18) Scharber, M. C.; Muhlbacher, D.; Koppe, M.; Denk, P.; Waldauf,

C.; Heeger, A. J.; Brabec, C. J. Adv. Mater. 2006, 18, 789–794.

(19) Reyes-Reyes, M.; Kim, K.; Carroll, D. L. Appl. Phys. Lett. 2005, 87,

083506.

(33) Atienza, C.; Insuasty, B.; Seoane, C.; Martın, N.; Ramey, J.; Rahman,

´

(20) Thompson, B. C.; Kim, B. J.; Kavulak, D. F.; Sivula, K.; Mauldin,

ꢀ

(21) Campoy-Quiles, M.; Ferenczi, T.; Agostinelli, T.; Etchegoin, P. G.;

Kim, Y.; Anthopoulos, T. D.; Stavrinou, P. N.; Bradley, D. D. C.; Nelson, J.

Nat. Mater. 2008, 7, 158–164.

(22) Hoppe, H.; Niggemann, M.; Winder, C.; Kraut, J.; Hiesgen, R.;

Hinsch, A.; Meissner, D.; Sariciftci, N. S. Adv. Funct. Mater. 2004, 14, 1005–

1011.

(23) Troshin, P. A.; Hoppe, H.; Renz, J.; Egginger, M.; Mayorova, J. Y.;

Goryachev, A. E.; Peregudov, A. S.; Lyubovskaya, R. N.; Gobsch, G.;

Sariciftci, N. S.; Razumov, V. F. Adv. Funct. Mater. 2009, 19, 779–788.

(24) Padinger, F.; Rittberger, R. S.; Sariciftci, N. S. Adv. Funct. Mater.

2003, 13, 1–4.

G. M. A.; Guldi, D. M. J. Mater. Chem. 2005, 15, 124–132.

(34) Shirai, Y.; Zhao, Y.; Cheng, L.; Tour, J. M. Org. Lett. 2004, 6, 2129–

2132.

C.; Frechet, J. M. J. Macromolecules 2007, 40, 7425–7428.

ꢀ

(35) Gomez-Escalonilla, M. J.; Langa, F.; Rueffb, J.-M.; Oswaldb, L.;

Nierengarten, J.-F. Tetrahedron Lett. 2002, 43, 7507–7511.

(36) Negishi, N.; Takimiya, K.; Otsubo, T.; Harima, Y.; Aso, Y. Chem.

Lett. 2004, 33, 654–655.

(37) Zhou, N.; Merschrod, E. F.; Zhao, Y. J. Am. Chem. Soc. 2005, 127,

14154–14155.

(38) Komatsu, K.; Takimoto, N.; Murata, Y.; Wan, T. S. M.; Wong, T.

Tetrahedron Lett. 1996, 37, 6153–6156.

(39) Timmerman, P.; Witschel, L. E.; Diederich, F.; Boudon, C.;

Gisselbrecht, J.-P.; Gross, M. Helv. Chim. Acta 1996, 79, 6–20.

(40) Timmerman, P.; Anderson, H. L.; Faust, R.; Nierengarten, J.-F.;

Habicher, T.; Seiler, P.; Diederich, F. Tetrahedron 1994, 52, 4925–4947.

(41) Anderson, H. L.; Faust, R.; Rubin, Y.; Diederich, F. Angew. Chem.,

Int. Ed. Engl. 1994, 33, 1366–1368.

(25) Motaung, D. E.; Malgas, G. F.; Arendse, C. J.; Mavundla, S. E.;

Oliphant, C. J.; Knoesen, D. J. Mater. Sci. 2009, 44, 3192–3197.

€

(26) Nguyen, L. H.; Hoppe, H.; Erb, T.; Gunes, S.; Gobsch, G.; Sariciftci,

N. S. Adv. Funct. Mater. 2007, 17, 1071–1078.

J. Org. Chem. Vol. 75, No. 5, 2010 1499

Zhou and Zhao

JOCArticle

intriguing aspect,^45-48conjugated oligoynes also exhibit

unique physical and chemical properties that are very useful

for the preparation of certain carbon-based functional poly-

mer materials and molecular devices.^5,49-57In the context of

material synthesis, conjugated oligoynes can be used as the

precursors to various carbon materials. For example, highly

ordered conjugated polyenyne networks can be obtainedfrom

topochemically controlled polymerization of oligoynes.^45,58-61

In addition, oligoynes have also been reported to form

graphite,⁵⁶multiwall carbon nanotubes,^55,62onion- and

diamond-like nanostructures,^63,64and porous carbon mate-

rials⁶⁵through various carbonization pathways such as

thermal decomposition.

SCHEME 2. Synthesis of C₆₀-Butadiyne-C₆₀Dumbbell 2a^a

Fullerene-oligoyne hybrids were first explored by

Diederich^39-41and Komatsu³⁸in 1996 as a new class of

molecular carbon allotropes. In 1999, the Hirsch group

reported a butadiyne-linked lipofullerene that underwent

diacetylene cross-linking reaction to form nanospheres in

solution under controlled conditions.⁶⁶Taking advantage

of the solid-state reactivity of oligoynes, Nierengarten and

co-workers in a recent study prepared a fullerene derivative

attached with polymerizable butadiyne moieties. Upon

annealing at 100 °C, the fullerene compound cross-linked

in the matrix of poly(phenylene vinylene)s to stabilize initi-

ally formed phases in BHJ solar cells, which resulted in

improved device performance.⁶⁷This thermally induced

cross-linking strategy opened a new avenue for optimization

of C₆₀-based solar cell devices.

^aReagents and conditions: (i) K₂CO₃, CH₃OH, THF, 99%; (ii) CuCl/

TMEDA, air, acetone, 75%; (iii) TMSA, PdCl₂(PPh₃)₂, CuI, Et₃N,

THF, 81%; (iv) K₂CO₃, CH₃OH, THF, 96%; (v) C₆₀, LHMDS, THF

then TFA, 25%.

Our group has recently investigated the thermally induced

polymerization of a 1,3,5,7-octatetrayne centered C₆₀-π-C₆₀

molecular dumbbell.³⁷To our great interest, the compound

was found to polymerize on the surface at 160 °C to form

uniform and highly ordered arrays of nanospheres. With this

success, we continued to investigate a series of analogous

C₆₀-π-C₆₀dumbbells 1a (see Scheme 1). In these com-

pounds, the structures of oligoyne and arylene π-linkage

groups were systematically varied by conjugation length in

order to facilitate the study of structure-property relation-

ships. In addition to this, the incorporation of oligoyne central

units was also envisaged to serve a springboard toward

nanostructured carbon networks with fullerenyl pendants;

for example, fullerene-oligoyne 1a was anticipated to yield

highly cross-linked polymers such as 1b via a thermally

induced graphitization⁵⁶pathway proposed in Scheme 1. Ex-

ploration in this direction should benefit the development of

novel fullerene-based carbon materials. In the following con-

tent, we present the synthetic routes to various fullerene-

oligoyne hybrids, in which Sonogashira coupling, Hay cou-

pling, and an in situ C₆₀alkynylation reaction were employed

asthe key steps. With these compoundsin hand, the interfacial

self-aggregation behavior and correlation with molecular and

experimental parameters were examined through combined

analyses using UV-vis spectroscopy, differential scanning

calorimetry (DSC), and atomic force microscopy (AFM).

(42) Chalifoux, W. A.; Tykwinski, R. R. Compt. Rend. Chim. 2009, 12,

341–358.

(43) Eisler, S.; Slepkov, A. D.; Elliott, E.; Luu, T.; McDonald, R.;

Hegmann, A. A.; Tykwinski, R. R. J. Am. Chem. Soc. 2005, 127, 2666–2676.

(44) Gibtner, T.; Hampel, F.; Gisselbrecht, J.-P.; Hirsch, A. Chem.-Eur.

J. 2002, 8, 408–432.

(45) Carbon-Rich Compounds: From Molecules to Materials; Haley, M.

M., Tykwinski, R. R., Eds.; Wiley-VCH: Weinheim, 2006.

(46) Yang, S.; Kertesz, M. J. Phys. Chem. A 2006, 110, 9771–9774.

(47) Itzhaki, L.; Altus, E.; Basch, H.; Hoz, S. Angew. Chem., Int. Ed. 2005,

44, 7432–7435.

(48) Szafert, S.; Gladysz, J. A. Chem. Rev. 2003, 103, 4175–4206.

€

(49) Haussler, M.; Zheng, R.; Lam, J. W. Y.; Tong, H.; Dong, H.; Tang,

B. Z. J. Phys. Chem. B 2004, 108, 10645–10650.

(50) Ding, L.; Olesik, S. V. Chem. Mater. 2005, 17, 2353–2360.

(51) Ding, L.; Olesik, S. V. Nano Lett. 2004, 4, 2271–2276.

(52) Bunz, U. H. F. Angew. Chem., Int. Ed. 1994, 33, 1073–1076.

ꢀ

ꢃ

(53) Hlavaty, J.; Kavan, L.; Kubista, J. Carbon 2002, 40, 345–349.

ꢀ

(54) Hlavaty, J.; Rathousky, J.; Zukal, A.; Kavan, L. Carbon 2001, 39,

53–60.

(55) Hlavaty, J.; Kavan, L.; Kasahara, N.; Oya, A. Chem. Commun. 2000,

737–738.

ꢀ

(56) Sarkar, A.; Okada, S.; Komatsu, K.; Nakanishi, H.; Matsuda, H.

Macromolecules 1998, 31, 5624–5630.

(57) Zhou, Q.; Carroll, P. J.; Swager, T. M. J. Org. Chem. 1994, 59, 1294–

1301.

(58) Curtis, S. M.; Le, N.; Fowler, F. W.; Lauher, J. W. Cryst. Growth

Des. 2005, 5, 2313–2321.

(59) Curtis, S. M.; Le, N.; Nguyen, T.; Ouyang, X.; Tran, T.; Fowler, F.

W.; Lauher, J. W. Supramol. Chem. 2005, 17, 31–36.

(60) Xiao, J.; Yang, M.; Lauher, J. W.; Fowler, F. W. Angew. Chem., Int.

Ed. 2000, 39, 2132–2135.

Results and Discussion

(61) Enkelmann, V. Chem. Mater. 1994, 6, 1337–1340.

ꢀ

Synthesis of C₆₀-Butadiyne-C₆₀dumbbells. The synthesis

of butadiyne-bridged C₆₀-π-C₆₀molecular dumbbell 2a is

outlined in Scheme 2. It began with desilylation of com-

pound 6³¹with K₂CO₃, which gave terminal alkyne 7 in 99%

yield. Hay coupling⁶⁸of 7 generated phenylbutadiynylene 8

in a yield of 75%. Compound 8 was cross-coupled with

trimethylsilylacetylene (TMSA) under the catalysis of Pd/Cu

(62) Hlavaty, J.; Kavan, L.; Okabe, K.; Oya, A. Carbon 2002, 40, 1131–

1150.

(63) Yasuda, A.; Kawase, N.; Banhart, F.; Mizutani, W.; Shimizu, T.;

Tokumoto, H. J. Phys. Chem. B 2002, 106, 1247–1251.

(64) Visscher, G. T.; Nesting, D. C.; Badding, J. V.; Biancoini, P. A.

Science 1993, 260, 1496–1499.

(65) Kijima, M.; Fujiya, D.; Oda, T.; Ito, M. J. Therm. Anal. Calor. 2005,

81, 549–554.

(66) Hetzer, M.; Clausen-Schumann, H.; Bayerl, S.; Bayerl, T. M.;

Camps, X.; Vostrowsky, O.; Hirsch, A. Angew. Chem., Int. Ed. 1999, 38,

1962–1965.

(67) Nierengarten, J.-F.; Setayesh, S. New. J. Chem. 2006, 30, 313–316.

(68) Hay, A. S. J. Org. Chem. 1962, 27, 3320–3321.

1500 J. Org. Chem. Vol. 75, No. 5, 2010

Zhou and Zhao

JOCArticle

SCHEME 3. Synthesis of Long C₆₀-Butadiyne-C₆₀

an intractable mixture rather than the desired product. This

unexpected difficulty hence forced us to seek an alternative

route to prepare suitable phenyloctatetrayne precursor.

As shown in Scheme 5, phenylbutadiyne 14 was cross

coupled with triisopropylsilylacetylene (TIPSA) to give com-

pound 17. Selective removal of the TMS group in 17 with

K₂CO₃, followed by a Hay coupling, afforded TIPS end-

capped phenyloctatetrayne 19. Oligomer 19 was desilylated

with TBAF to give compound 20, which was immediately

subjected to an in situ alkynylation with C₆₀, furnishing the

target C₆₀-tetrayne-C₆₀dumbbell 3a in 31% yield.

Dumbbell 2b^a

Following a similar strategy, a longer octatetrayne-

bridged bisfullerenyl dumbbell 3b was prepared. The de-

tailed synthetic steps are outlined in Scheme 6. Mono-TIPS-

protected phenylacetylene dimer 11 was first elongated by

one more acetylenic unit through a mixed Hay coupling with

excess TMSA, affording phenylacetylene oligomer 21. Com-

pound 21 was selectively desilylated with K₂CO₃to give

terminal diyne 22, which underwent an oxidative homocou-

pling to form octatetrayne centered phenylacetylene oligo-

mer 23. Removal of the TIPS groups in 23 with TBAF,

followed by an in situ alkynylation with C₆₀, gave bisfuller-

ene dumbbell 3b in a satisfactory yield of 33%.

Synthesis of C₆₀-Dodecahexayne-C₆₀Dumbbell. At this

point, all the synthesized butadiyne- and octatetrayne-

bridged bisfullerene dumbbells showed good chemical sta-

bility at room temperature due to the presence of bulky

fullerenyl end-capping groups. Indeed, these compounds

could be stored at room termperature under N₂for more

than 2 months without significant decomposition. After

longer term storage, however, the fullerene-oligoyne ad-

ducts gradually formed insoluble black substances likely as a

result of cross-linking reactions in the solid state. The effort

to construct longer oligoyne-bridged dumbbells ensued,

although the increasing instability of higher oligoynes was

recognized as a potential risk beforehand. Outlined in

Scheme 7 is the synthesis of a C₆₀-dodecahexayne-C₆₀

dumbbell 4. First, desilylation of compound 17, followed

by Hay coupling with excess TMSA, gave phenylhexatriyne

precursor 25. Compound 25 was subjected to another itera-

tion of desilylation and Hay coupling to yield TIPS end-

capped phenyldodecahexayne 27. Hexayne 27 was isolated

through flash column chromatography as a brownish wax

with moderate chemical stability. Treating 27 with TBAF led

to terminal alkyne intermediate 28, which showed very poor

chemical stability. For this reason, compound 28 was im-

mediately reacted with C₆₀following the in situ alkynylation

protocol. After quenching with TFA, C₆₀-dodecahexayne-

C₆₀dumbbell 4 was obtained in an overall yield of 5% based

on the consumption of precursor 27. Like its hexayne pre-

cursors, compound 4 was unstable, which allowed only a

fleeting lifetime for ¹H NMR spectroscopic characterization.

It is also worth noting that terminal alkyne intermediates

involved in this synthetic route, including 18, 26, and 28, are

also quite unstable. Therefore, once acquired they were

immediately carried on to the subsequent synthetic steps

without further purification. In particular, phenyldodeca-

hexayne 28 was found to retain moderate stability only in

dilute solution. Once the solvent was evaporated off, com-

pound 28 decomposed instantaneously into insoluble black

solids. (Although conjugated oligoynes, particularly higher

oligoynes, have been reported to be explosive in nature, we

^aReagents and conditions: (i) CuCl/TMEDA, air, acetone, 43%;

(ii) TBAF, THF, 81%; (iii) C₆₀, LHMDS, THF then TFA, 32%.

to yield oligomer 9, which was subsequently converted into

terminal diyne 10 via protiodesilylation. Compound 10 was

subjected to an in situ alkynylation^31,34with C₆₀using

LHMDS as base, followed by quenching with trifluoroacetic

acid (TFA), affording the first target C₆₀-butadiyne-C₆₀

dumbbell 2a in 25% yield.

In a similar manner, a longer C₆₀-butadiyne-C₆₀dumb-

bell 2b was prepared through the synthetic route shown in

Scheme 3. The synthesis began with a monotriisopropylsilyl

(TIPS)-protected phenylacetylene dimer 11.³¹Oxidative

homocoupling of 11 in the presence of Cu(I) catalyst gave

phenylbutadiynylene oligomer 12 in 43% yield. Removal of

the TIPS groups in 12 with tetrabutylammonium fluoride

(TBAF) gave oligomer 13, which was then converted into

bisfullerenyl dumbbell 2b via the in situ alkynylation proto-

col described above.

Synthesis of C₆₀-Octatetrayne-C₆₀dumbbells. With the

success in the preparation of butadiynylene-bridged bisful-

lerene dumbbells, the synthesis of their 1,3,5,7-octatetrayne-

bridged homologues was then undertaken. Our initial

attempt was made on C₆₀-octatetrayne-C₆₀dumbbell 3a,

using the synthetic route shown in Scheme 4, wherein TMS-

protected phenyloctatetrayne 16 was planned as a key inter-

mediate. To make compound 16, phenylbutadiyne 14 was

first prepared viaa mixed Haycoupling between phenylacety-

lene 6 and excess TMSA. In this reaction, compound 14

was easily separated from another major product, bis-

(trimethylsilyl)butadiyne, through flash column chromato-

graphy in a satisfactory yield of 68%. Desilylation of 14

followed by another Hay coupling afforded bis(iodophenyl)

end-caped octatetrayne 15. With compound 15 in hand, the

desired intermediate 16 was supposed to be readily accessible

via a Sonogashira coupling with TMSA. However, the

coupling reaction executed under typical Sonogashira con-

ditions (i.e., Pd(PPh₃)₂Cl₂/CuI and Et₃N in THF) resulted in

J. Org. Chem. Vol. 75, No. 5, 2010 1501

Zhou and Zhao

JOCArticle

SCHEME 4. Attempted Synthesis of C₆₀-Octatetrayne-C₆₀Dumbbell 3a^a

^aReagents and conditions: (i) TMSA, CuCl/TMEDA, air, acetone, 68%; (ii) (a) K₂CO₃, CH₃OH, THF, (b) CuCl/TMEDA, air, acetone, 53%;

(iii) TMSA, PdCl₂(PPh₃)₂, CuI, Et₃N, THF.

SCHEME 5. Synthesis of C₆₀-Octatetrayne-C₆₀Dumbbell 3a^a

^aReagents and conditions: (i) TIPSA, PdCl₂(PPh₃)₂, CuI, Et₃N, THF, 86%; (ii) K₂CO₃, CH₃OH, THF; (iii) CuCl/TMEDA, air, acetone, 53% over two

steps; (iv) TBAF, THF, 77%; (v) C₆₀, LHMDS, THF then TFA, 31%.

have so far not experienced any explosions in handling the

aforementioned oligoyne species. Nevertheless, caution still

must be exercised in handling these unstable oligoyne-de-

rived compounds.)

Synthesis of Star-Shaped Oligoyne-Centered Tetrafullerene

Adducts. Apart from the linear C₆₀-oligoyne-C₆₀dumb-

bells, a series of star-shaped oligoyne cored tetrafullerene

adducts (see Figure 1) was also pursued in our synthesis.

The effort toward the synthesis of compound 29a is

described in Scheme 8. Starting from methyl 3,5-diiodo-

benzoate (30), benzaldehyde 32 was obtained through two

steps of typical functional group interconversions. Com-

pound 32 was then converted into terminal alkyne 34 via a

Corey-Fuchs reaction.⁶⁹Hay coupling of 34 led to phenyl-

diyne 35 as a pale white solid with limited stability. Com-

pound 35 was immediately subjected to a Sonogashira

coupling reaction with terminal alkyne 36 to yield star-

shaped phenylacetylene oligomer 37. Treatment of oligomer

37 with TBAF in THF removed the TIPS end groups,

affording compound 38 which is the key precursor to target

(69) Corey, E. J.; Fuchs, P. L. Tetrahedron Lett. 1972, 36, 3769–3772.

1502 J. Org. Chem. Vol. 75, No. 5, 2010

Zhou and Zhao

JOCArticle

SCHEME 6. Synthesis of Long C₆₀-Octatetrayne-C₆₀Dumbbell 3b^a

^aReagents and conditions: (i) TMSA, CuCl/TMEDA, air, acetone, 79%; (ii) K₂CO₃, CH₃OH, THF; (iii) CuCl/TMEDA, air, acetone, 85% over two

steps; (iv) TBAF, THF, 84%; (v) C₆₀, LHMDS, THF then TFA, 33%.

SCHEME 7. Synthesis of C₆₀-Dodecahexayne-C₆₀Dumbbell 4^a

^aReagents and conditions: (i) K₂CO₃, CH₃OH, THF; (ii) TMSA, CuCl/TMEDA, air, acetone, 90% over two steps; (iii) K₂CO₃, CH₃OH, THF;

(iv) CuCl/TMEDA, air, acetone, 39% over two steps; (v) TBAF, THF; (vi) C₆₀, LHMDS, THF then TFA, 5% over two steps.

tetrafullerene adduct 29a. However, the in situ alkynylation

reaction between C₆₀and 38 in the presence of LHMDS

resulted in some insoluble substances, the molecular struc-

tures of which could not be clearly identified.

followed by another Hay coupling afforded octatetrayne-

cored phenylacetylene oligomer 44 in a very good yield.

Compound 44 was desilylated with TBAF to afford terminal

alkyne 45. To our dismay, the synthesis of 29b also reached a

dead end at this point, as precursor 45 was not able to

produce the desired tetrafullerene adduct via the in situ

alkynylation reaction.

Speculating that the low solubility of tetrafullerene pro-

ducts 29a,b could be the main reason for the failed in situ

alkynylation reactions, we continued to pursue another group

of star-shaped tetrafullerene adducts (5a and 5b), which

contain more solubilizing bis(decyloxy)-substituted phenyl-

ene units. As illustrated in Scheme 10, a Sonogashira coupling

reaction between phenylbutadiyne 35 and phenylacetylene

In parallel with the above synthetic effort for 29a, an

octatetrayne-centered star-shaped tetrafullerene adduct 29b

was also targeted. As shown in Scheme 9, terminal alkyne 34

was first deprotonated with a strong base, LDA, and then

silylated with TMSCl to give compound 39. From com-

pound 39, phenylacetylene oligomer 40 was readily prepared

in 89% yield via a Sonogashira coupling reaction with 36.

Compound 40 was desilylated with K₂CO₃to form terminal

alkyne 41, which was subjected to a Hay coupling with excess

TMSA to produce oligomer 42. Selective desilylation of 42

J. Org. Chem. Vol. 75, No. 5, 2010 1503

Zhou and Zhao

JOCArticle

SCHEME 8. Attempted Synthesis of Star-Shaped Tetrafuller-

ene Adduct 29a^a

FIGURE 1. Star-shaped tetrafullerene-oligoyne adducts.

dimer 11 gave TIPS-protected phenylacetylene oligomer 46 in

a yield of 86%. Removal of the TIPS groups in 46 with TBAF

afforded terminal alkyne 47, which was subsequently con-

verted into tetrafullerene adduct 5a via the in situ alkynylation

reaction with C₆₀. Although the yield of the alkynylation

reaction was around 20%, it is still a satisfactory result

considering the fact that four fullerenyl groups were incorpo-

rated in a single synthetic step.

In a similar manner, octatetrayne-centered tetrafullerene

adduct 5b was anticipated to be readily prepared from oligo-

mer precursor 52 as shown in Scheme 11. The synthesis of

TIPS protected star-shaped phenylacetylene oligomer 52 was

implemented following the same iterative strategy as used in

the synthesis of oligomers 45 and 47. When oligomer 52 was

subjected to a typical desilylation with TBAF, however, a new

problem emerged: the resulting terminal alkyne 53 was too

unstable to be isolated asa neat product. In fact, compound53

was found to decompose so rapidly into a dark colored

substance, presumably through cross-linking or polymeriza-

tion of the tetrayne moieties, that no opportunity could be

seized to carry it into subsequent in situ alkynylation reaction.

In this case, it was the instability of precursor 53 that thwarted

the acquisition of tetrafullerene adduct 5b, albeit compound

5b was envisaged to be a stable and soluble product.

Thermal Properties. Conjugated oligoynes such as diacety-

lenes, triynes, and tetraynes, show the propensity to poly-

merize in the solid state or in concentrated solutions upon

activation by heat, irradiation (e.g., UV-vis, γ-ray), or

mechanical forces (e.g., pressure).⁴⁵The polymerization

may take place through a diversity of mechanisms. The most

intriguing one is the topochemically controlled polymeriza-

tion, through which highly ordered poly(enyne) networks

can be obtained.^58-61Scheme 12 illustrates the possible

topochemical polymerization pathways for octatetraynes,

which lead to polyacetylene (PA), polydiacetylene (PDA),

and polytriacetylene (PTA) frameworks, respectively.

^aReagents and conditions: (i) DIBAL, CH₂Cl₂, 95%; (ii) PCC, CH₂Cl₂,

95%; (iii) CBr₄, PPh₃, CH₂Cl₂, 93%; (iv) LDA, THF, 87%; (v) CuCl/

TMEDA, air, acetone, 65%; (vi) PdCl₂(PPh₃)₂, CuI, Et₃N, THF, 76%;

(vii) K₂CO₃, CH₃OH, THF, 73%.

For topochemical polymerization to occur, the oligoyne

monomers must be organized with particular geometries in

the solid state to ensure minimal atomic and molecular

motion during the transformation.^5,45,58-61The specific

demand for packing considerably limits the access to highly

ordered carbon nanostructures via topochemical polymeri-

zation of sterically hindered oligoynes. In view of the bulki-

ness of end groups (i.e., bis(decyloxyl)phenyl and fullerenyl)

present in the oligoyne derivatives herein synthesized, the

possibility of inducing their topochemical polymerization is

ruled out. On the other hand, for oliogynes with random

solid-state structures, mixed polymerization or cross-linking

reactions usually prevail at elevated temperatures resulting

in interesting carbonized materials, such as carbon nano-

spheres,^50,51,66carbon nanotubes,^55,62graphite fibers, and

ribbons.⁵⁶To shed light on the thermal properties and

reactivities, differential scanning calorimetric (DSC) analy-

sis was performed on C₆₀-oligoyne-C₆₀dumbbells (2 and

3) and corresponding phenyloligoyne precursors (9 and 19)

under N₂atmosphere.

Figure 2A shows the DSC results of short C₆₀-diyne-C₆₀

dumbbell 2a. The thermogram features a broad exothermic

peak with moderate intensity centered at 145 °C and a

noticeable hump (exothermic) around 198 °C. Compared

to the DSC profile of diyne precursor 9 (see Figure S-100,

Supporting Information), the first exothermic peak can be

ascribed to a low-degree, random cross-linking of diyne

moieties, and the bisfullerene-diyne dumbbell 2a appears

to be more thermally robust than diyne precursor 9 in the

1504 J. Org. Chem. Vol. 75, No. 5, 2010

Zhou and Zhao

JOCArticle

SCHEME 9. Attempted Synthesis of Star-Shaped Tetrafullerene Adduct 29b^a

^aReagents and conditions: (i) LDA, THF then TMSCl, 81%; (ii) 36, PdCl₂(PPh₃)₂, CuI, Et₃N, THF, 89%; (iii) K₂CO₃, CH₃OH, THF, 100%;

(iv) TMSA, CuCl/TMEDA, air, acetone, 89%; (v) K₂CO₃, CH₃OH, THF, 81%; (vi) CuCl/TMEDA, air, acetone, 86%; (vii) TBAF, THF.

temperature range of ca. 100-270 °C, owing to the presence

of bulky C₆₀end-capping groups which considerably hinders

the thermal reactivity of the diyne moieties. At temperatures

higher than 270 °C, the DSC trace drifts abruptly to the

endothermic direction, which is likely due to the decomposi-

tion of the phenylacetylene components.⁷⁰

SCHEME 10. Synthesis of Star-Shaped Butadiyne-Cored

Tetrafullerene Adduct 5a^a

The DSC profile of short C₆₀-tetrayne-C₆₀dumbbell 3a

(Figure 2B) shows only one relatively broad exothermic peak

ranging from 156 to 240 °C with a maximum at 212 °C. The

broad peak width suggests that the tetrayne moiety in 3a

undergoes polymerization in a random, rather than the

regioselective (topochemical) manner. Unlike that of diyne

dumbbell 2a, the DSC thermogram of tetrayne dumbbell 3a

remains nearly flat from 240 to 350 °C, manifesting good

thermal stability for the polymerized product in this tem-

perature range. Moreover, the enthalpy for the exothermic

process (ΔH) is determined to be 77.6 kJ mol^-1. Since this

3

value is considerably smaller than that of tetrayne precursor

19 (317.7 kJ mol^-1), it can be inferred that the degree of

polymerization involved is kind of low.

3

The DSC trace of long C₆₀-diyne-C₆₀dumbbell 2b

(Figure 2C) shows a weak exothermic peak at 141 °C along

with a barely noticeable hump at 196 °C. The features herein

are clear indicative of appreciable thermal robustness and

very low solid-state reactivity of 2b in comparison to the

^aReagents and conditions: (i) PdCl₂(PPh₃)₂, CuI, Et₃N, THF, 86%; (ii)

TBAF, THF, 100%; (iii) LHMDS, C₆₀, THF then TFA, 20%.

(70) Karim, S. M. A.; Nomura, R.; Masuda, T. Polym. Bull. 1999, 43,

305–310.

J. Org. Chem. Vol. 75, No. 5, 2010 1505

Zhou and Zhao

JOCArticle

SCHEME 11. Attempted Synthesis of Star-Shaped Octatetrayne-Cored Tetrafullerene Adduct 5b^a

^aReagents and conditions: (i) PdCl₂(PPh₃)₂, CuI, Et₃N, THF, 94%; (ii) K₂CO₃, CH₃OH, THF, 83%; (iii) TMSA, CuCl/TMEDA, air, acetone, 84%;

(iv) K₂CO₃, CH₃OH, THF, 91%; (v) CuCl/TMEDA, air, acetone, 83%; (vi) TBAF, THF, 0%.

other fullerene-oligoyne species. The DSC thermogram of

long C₆₀-tetrayne-C₆₀dumbbell 3b (Figure 2D) shows a

strong, broad exotherm peaking at 140 °C, together with a

weak exothermic hump at 198 °C. The features are tied to

tetrayne polymerization or cross-linking in the solid state,

and the temperature range in which the thermal reactions

take place are much lower than that for short C₆₀-tetrayne-

C₆₀dumbbell 3a. The increased thermal reactivity is likely

due to the longer distance between the bulky fullerenyl

groups and central tetrayne unit in 3b, which in turn reduces

the steric hindrance. In addition to the exothermic features, a

pronounced baseline drift to the endothermic direction is

observed at temperature higher than 270 °C, likely due to the

degradation of the phenylacetylene moieties.

In our experiments, each compound was measured by

UV-vis spectroscopy under three different circumstances,

(1) in solution (toluene), (2) in solid thin film at room

temperature, and (3) in solid thin film after heating at

160 °C for ca. 1 h. The heating of thin films was intended

to induce solid-state polymerization reactions. The heating

temperature was chosen at 160 °C for a 2-fold reason: first, it

was a common temperature at which most of the

oligoyne-C₆₀adducts show exothermic processes in their

DSC data (see Figure 2). Second, both the fullerene and

phenylene units are known to be stable at this temperature so

that only oligoyne thermal polymerization can be induced

for investigation.

In line with the results of DSC analysis, the UV-vis

absorption profiles of diyne-centered fullerene adducts 2a,

2b, and 5a did not show significant changes before and after

thermal annealing, indicating relative thermal stability of the

To investigate the structural changes of the oligoyne units

in response to thermal annealing, UV-vis spectroscopic

analysis was performed on the C₆₀-oligoyne-C₆₀adducts.

1506 J. Org. Chem. Vol. 75, No. 5, 2010

Zhou and Zhao

JOCArticle

FIGURE 2. DSC profiles for (A) short C₆₀-diyne-C₆₀2a, (B) short C₆₀-tetrayne-C₆₀3a, (C) long C₆₀-diyne-C₆₀2b, and (D) long

C₆₀-tetrayne-C₆₀3b. Scan rate: 5 °C/min.

SCHEME 12. Structures of Carbon Polymers Resulting from Different Probabilities of Topochemical Polymerization of Octatetraynes

diyne moieties at 160 °C (see Figure S-101, Supporting

Information).

For tetrayne-centered bisfullerene dumbbells 3a and 3b,

pronounced thermal reactivity of tetrayne moieties at 160 °C

was detected by UV-vis analysis. As shown in Figure 3A,

the UV-vis spectrum of short C₆₀-tetrayne-C₆₀dumbbell

3a measured in solution shows three distinctive absorption

bands in the region of 380-460 nm, which are characteristic

of the vibronic modes of a conjugated tetrayne. In the

spectrum of its solid thin film, the same set of vibronic bands

J. Org. Chem. Vol. 75, No. 5, 2010 1507

Zhou and Zhao

JOCArticle

FIGURE 3. UV-vis spectra of tetrayne-centered bisfullerene dumbbells 3a and 3b measured in solution, solid film, and solid film after heating

at 160 °C for ca. 1 h.

is still discernible, but appears to be substantially broadened

in shape, likely resulting from aggregation effects. After

heating the film at 160 °C for 1 h, markedly different

UV-vis absorption features can be observed: the three

characteristic tetrayne bands disappear completely, while

the high-energy bands (below 350 nm) and the fullerene

absorption tail (beyond ca. 550 nm) are hardly changed.

The UV-vis results in association with its DSC data corro-

borate the occurrence of thermally induced solid-state poly-

merization of the tetrayne moieties in the thin film of 3a upon

thermal annealing.

To gain a deeper insight into the thermal reactivity of

tetrayne dumbbell 3a, IR spectroscopic analysis was under-

taken on its solid samples before and after heating at 160 °C

FIGURE 4. IR spectra for short C₆₀-tetrayne-C₆₀dumbbell 3a

before and after heating at 160 °C for 1 h.

for 1 h. From the IR data given in Figure 4, it is observed that

the vibrational frequency at ca. 2100 cm^-1characteristics of

CtC bond stretching completely vanished after thermal

annealing. The disappearance of the CtC band indicates

that the thermal reactions involve acetylenic units and the

resulting polymers contain highly symmetrical CtC struc-

tures and/or fused aromatic rings as proposed in Scheme 1.⁵⁶

In the meantime, the heated thin film gives rise to a new

vibrational band at 1728 cm^-1, which is typical of CdO

stretching. Given the fact that the heating of the solid

samples was conducted in an open air environment, it is very

likely that oxygen participated in the solid-state reaction to

form carbonyl groups at the terminal sites of the polymer

networks. To further investigate the crystalline properties of

the polymers resulting formed thermal annealing, X-ray

powder diffraction (XRD) analysis was also undertaken.

However, the results do not manifest any crystalline features.

In Figure 3B, theUV-visspectrum of long C₆₀-tetrayne-

C₆₀dumbbell 3b measured in solution shows two discernible

vibronic bands of tetrayne in the region of 390 to 480 nm.

The solid thin film gives rise to a spectral envelope silimar

to that obtained in the solution phase, indicating relati-

vely weak π-π aggregation as a result of increased bulky

solubilizing bis(decyloxy)phenylacetylene subunits in com-

parison to its short analogue 3a. After heating the solid

film of 3b at 160 °C for 1 h, the UV-vis absorption bands

corresponding to the tetrayne moiety are completely

lost, which offers another piece of evidence for solid-state

polymerization of the tetrayne units in 3b in addition to the

DSC results.

Morphological Properties. As mentioned in the Introduc-

tion, the nanomorphology of fullerene-based materials has

become a topic of growing interest, owing to its importance

for the optimization of fullerene-polymer BHJ solar cells. In

our study, the morphological properties of oligoyne-cored

fullerene adducts on surface were studied by atomic force

microscopic (AFM) analysis. In the experiments, samples of

oligoyne-C₆₀adducts were first prepared in dilute solutions

(ca. 10^-6-10^-7M in toluene). The solutions were spin-cast

on freshly cleaved mica surfaces at a spin rate of 2,000 rpm.

Surface morphologies of the resulting thin films were exam-

ined by AFM (operated in the noncontact mode) both before

and after thermal annealing at 160 °C for 1 h. The acquired

AFM images are detailed in the Supporting Information.

Short diyne dumbbell 2a is found to agglomerate into

spherical nanoclusters on the mica surface before heating,

and the distribution of the nanospheres of 2a is in a relatively

narrow range of ca. 10-20 nm. After the sample is heated at

160 °C for 1 h, there are no noticeable morphological

changes observed for the nanospheres (Figure S-102, Sup-

porting Information).

Long diyne dumbbell 2b aggregates on mica forming a

pattern of cross-linked “worms”. The vertical heights of

1508 J. Org. Chem. Vol. 75, No. 5, 2010

Zhou and Zhao

JOCArticle

FIGURE 5. Surface morphology of short C₆₀-tetrayne-C₆₀dumbbell 3a on mica measured by AFM: (A) before heating; (B) after heating at

160 °C for ca. 1 h.

FIGURE 6. Surface morphology of long C₆₀-tetrayne-C₆₀dumbbell 3b on mica measured by AFM: (A) before heating; (B) after heating at

160 °C for ca. 1 h.

these “worms” are rather uniform, ranging from ca. 4 to 6 nm

(Figure S-103, Supporting Information). Like the short

diyne dumbbell, these unique nanostructures show no sig-

nificant changes in morphology after heating, which is

consistent with the relatively high thermal stability of diyne

species as revealed by previous DSC and UV-vis analyses.

The most remarkable morphological transformation cor-

responding to solid-state polymerization is found in the case

of short C₆₀-tetrayne-C₆₀dumbbell 3a. As shown in Figure 5,

compound 3a forms discrete “flake-like islands” on the

surface with vertical heights around 1-2 nm. The thickness

of these aggregates fits well the depth of nanostructures

composed of single or double molecular layer of compound

3a, given that the diameter of C₆₀is approximately 1 nm. After

heating at 160 °C for ca. 1 h, the random “flakes” were

transformed into an ordered array of spherical nanoparticles

on the surface, with rather narrowly distributed vertical

diameters. Cross-section analysis shows that the average

vertical diameter of these nanospheres is around 20 nm. The

transformation from random aggregates of 3a into ordered,

uniform nanospheres by means of thermal annealing can be

relatedtothe solid-statepolymerizationofthe tetraynemoiety

in 3a as revealed by DSC, UV-vis, and IR analyses.

roughness of ca. 2-4 nm. After heating at 160 °C for ca. 1 h,

the thin film became smoother and the roughness was

measured to be less than 1 nm on average (see Figure 6B).

In contrast to the case of 3a, there are no discrete nano-

structures observed from the AFM image of thermally

annealed tetrayne 3b. It therefore transpires that the addi-

tional two alkyloxy-substituted phenylacetylene subunits

have greatly altered the surface aggregation behavior of

dumbbell-shaped bisfullerene adducts.

Star-shaped tetrafullerene-diyne adduct 5a forms a mix-

ture of spherical, semispherical, and short “worm-like”

nanoaggregates on the surface of mica (Figure S-104, Sup-

porting Information). The height distribution of these nano-

structures is narrow and measured to be about 1 nm, which

corresponds well to single molecular layered aggregates.

After thermal annealing at 160 °C for ca. 1 h, the morpho-

logical features are virtually unchanged. This result attests to

the good thermal stability of 5a at 160 °C as indicated by its

UV-vis and DSC analyses.

Conclusions

We have demonstrated in this paper the synthesis of a series

of dumbbell-shaped linear bisfullerene-end-capped conjugated

oligoynes as well as a star-shaped tetrafullerene-oligoyne. The

employment of butadiyne and octatetrayne central bridges

resulted in stable fullerene-oligoyne adducts at ambient tem-

Long C₆₀-tetrayne-C₆₀dumbbell 3b displays better film

forming properties than its short homologue 3a. As can be

seen from Figure 6A, the surface morphology for aggregates

of 3b appears as a random, continuous thin film with a

J. Org. Chem. Vol. 75, No. 5, 2010 1509

Zhou and Zhao

JOCArticle

1

peratures, whereas the stability of adducts involving higher

oligoynes decreased sharply. The stability and reactivity of the

oligoyne units in the solid state at elevated temperatures were

examined by UV-vis, FT-IR, and DSC techniques. Morpho-

logical changes of these compounds in association with ther-

mally induced polymerization were monitored by AFM

imaging. The conjugated diyne moieties of corresponding

fullerene-oligoyne adducts showed relative thermal stability

at temperatures below ca. 250 °C, although evidence for low-

degree diyne cross-linking was obtained from DSC and UV-vis

analyses. Thermal annealing therefore had rather insignificant

effects on the nanomorphologies of the interfacial aggregates of

fullerene-diyne adducts. Fullerene-tetrayne adducts, in con-

trast, were found to be more thermally labile. The increased

thermal reactivity of the tetrayne unit exerted drastic influence

on the morphological features of the fullerene-tetrayne aggre-

gates. The most noteworthy result comes from the thermal

annealing of short fullerene-tetrayne dumbbell 3a, where

thermally induced tetrayne polymerization in the solid state

transformed amorphous flake-like aggregates into uniform,

highly ordered arrays of nanospheres. On the basis of the

combined thermal, spectroscopic, and morphological analyses,

a general correlation between surface aggregation behavior and

molecular structure can be established for the fullerene-

oligoyne hybrid compounds. The more fullerene compo-

nents present in molecular composition, the much stronger

tendency the molecules would display to aggregate into discrete

spherical nanostructures on surface. On the other hand, the

incorporation of more solubilizing alkyl groups renders reduced

ability to form discrete nanoaggregates but facilitates the

formation of continuous thin films. Finally, it is believed that

better understanding of the fundamental solid-state properties

should form the key stepping stone for finding practical uses of

these new fullerene-oligoyne adducts in molecular device

applications.

1464 cm^-1; H NMR (CDCl₃/CS₂, 500 MHz) δ 7.22 (s, 2H),

7.15 (s, 2H), 7.08 (s, 2H), 4.13 (t, J = 6.1 Hz, 4H), 4.10 (t,

J = 5.2 Hz, 4H), 1.96-1.89 (m, 8H), 1.68-1.62 (m, 4H),

1.60-1.54 (m, 4H), 1.40-1.20 (m, 48H), 0.88 (t, J = 6.5 Hz,

6H), 0.83 (t, J = 7.3 Hz, 6H); ¹³C NMR (CDCl₃/CS₂, 125 MHz)

δ 155.2, 154.4, 151.6, 151.4, 147.8, 147.5, 146.8, 146.61, 146.60,

146.4, 146.0, 145.9, 145.7, 145.64, 145.57, 144.9, 144.7, 143.4,

142.82, 142.79, 142.33, 142.26, 142.21, 142.1, 141.9, 141.8,140.6,

140.5, 136.3, 135.4, 117.6, 117.1, 114.2, 113.5, 98.4, 80.5, 80.1,

79.9, 69.9, 69.6, 62.1, 55.7, 32.3, 30.4, 30.2, 30.1, 30.0 (br), 29.8

(br), 29.6 (br), 29.4, 29.1, 26.8, 26.4, 23.1, 14.51, 14.47; HRMS

(MALDI-TOF) calcd for

C₁₈₀H₉₀O₄, 2314.6839, found

2315.5138 [M þ H]^þ.

Compound 2b. Compound 2b (32 mg, 0.010 mmol, 32%) was

obtained as a brownish solid via the same in situ alkynylation

protocol as described in the synthesis of 2a, using compound 13

(53 mg, 0.031 mmol), C₆₀(112 mg, 0.156 mmol), LHMDS

(0.16 mL, 1 M, 0.16 mmol), and dry THF (150 mL): IR (KBr)

2920, 2851, 2199, 2139, 2090, 1653, 1603, 1495, 1464, 1424 cm^-1

;

¹H NMR (CDCl₃/CS₂, 500 MHz) δ 7.29 (s, 2H), 7.18 (s, 2H),

7.13 (s, 2H), 7.04 (s, 2H), 7.03 (s, 2H), 4.15 (m, 8H), 4.04 (m, 8H),

1.96-1.85 (m, 16H), 1.70-1.50 (m, 16H), 1.40-1.20 (m, 96H),

0.92-0.82 (m, 24H); ¹³C NMR (CDCl₃/CS₂, 125 MHz) δ 155.3,

154.8, 153.9, 153.6, 151.9, 151.8, 147.9, 147.7, 147.0, 146.7,

146.5, 146.1, 146.0, 145.9, 145.75, 145.67, 145.0, 144.8, 143.5,

143.3, 142.90, 142.87, 142.4, 142.35, 142.29, 142.2, 141.98,

141.91, 140.7, 140.6, 136.4, 135.5, 118.2, 117.6, 117.4, 117.2,

115.6, 115.2, 113.3, 113.0, 97.9, 92.3, 92.0, 80.5, 79.9, 79.7, 70.1,

70.0, 69.8, 62.2, 55.8, 32.2, 30.2, 30.1, 30.01, 29.96, 29.89, 29.85,

29.7, 29.63, 29.57, 29.4, 26.8, 26.3, 26.2, 22.9, 14.4; HRMS

(MALDI-TOF) calcd for

3139.2679 [M]^þ.

C₂₃₆H₁₇₈O₈, 3139.3522, found

Compound 3a. Compound 3a (32 mg, 0.016 mmol, 31%) was

obtained as a brownish solid via the same in situ alkynylation

protocol as described in the synthesis of 2a, using compound 20

(48 mg, 0.052 mmol), C₆₀(189 mg, 0.263 mmol), LHMDS

(0.27 mL, 1 M, 0.27 mmol), and dry THF (240 mL): IR (KBr)

2920, 2850, 2190, 2115, 1628 cm^-^{1 1}H NMR (CDCl₃/CS₂,

;

500 MHz) δ 7.19 (s, 2H), 7.12 (s, 2H), 7.04 (s, 2H), 4.10 (t,

J = 6.5 Hz, 4H), 4.08 (t, J = 7.1 Hz, 4H), 1.90-1.84 (m, 8H),

1.64 (m, 4H), 1.54 (m, 4H), 1.46-1.15 (m, 48H), 0.90 (t, J =

6.2 Hz, 6H), 0.83 (t, J = 6.0 Hz, 6H); ¹³C NMR (CDCl₃/CS₂,

125 MHz) δ 156.7, 154.7, 151.9, 151.7, 148.2, 147.9, 147.1, 147.0,

146.9, 146.8, 146.3, 146.20, 146.16, 146.03, 145.99, 145.90, 145.2,

145.0, 143.8, 143.2, 143.1, 142.7, 142.6, 142.5, 142.4, 142.22,

142.16, 140.93, 140.89, 136.6, 135.7, 118.2, 117.3, 115.7, 112.3,

99.3, 80.6, 80.5, 75.4, 70.3, 70.0, 69.6, 65.4, 62.4, 56.0, 32.6 (br),

30.5, 30.3 (br), 30.1 (br), 26.7 (br), 23.4 (br), 14.8 (br); HRMS

Experimental Section

General Methods. All chemicals were purchased from com-

mercial sources and used as received. All reactions were per-

formed in standard, oven-dried glassware under a N₂atmos-

phere unless otherwise noted. THF was distilled from sodium/

benzophenone. Et₃N and toluene were distilled from LiH.

Catalysts Pd(PPh₃)₄and Pd(PPh₃)₂Cl₂were prepared from

PdCl₂according to standard procedures. Hay catalyst (CuCl/

TMEDA in acetone) was prepared according to the procedure

reported in the literature.⁷¹Thin-layer chromatography (TLC)

was carried out with silica gel 60 F254 covered on plastic sheets

and visualized by UV light or KMnO₄stain, and flash column

chromatographic separation was performed over silica gel.

Compound 2a. To an oven-dried round-bottomed flask equi-

pped with a magnetic stirrer were added compound 10 (50 mg,

0.057 mmol), C₆₀(205 mg, 0.286 mmol), and dry THF (240 mL).

The mixture was sonicated at 0 °C for 5 h to form a brownish

suspension. Lithium hexamethyldisilazide (LHMDS) (0.29 mL,

1 M, 0.29 mmol) was added dropwise at rt under N₂protection.

The mixture was further stirred at rt for 1 h, and then trifluoro-

acetic acid (TFA) (0.1 mL) was added to the suspension to

quench the reaction. Removal of the solvent in vacuo followed

by silica flash column chromatography (hexanes/toluene, 3:1)

afforded compound 2a (32 mg, 0.014 mmol, 25%) as a brown

solid: IR (KBr) 2921, 2852, 2200, 2087, 1654, 1602, 1496,

(MALDI-TOF) calcd for

2362.8538 [M]^þ.

C₁₈₀H₉₀O₄, 2362.6839, found

Compound 3b. Compound 3b (36 mg, 0.011 mmol, 33%) was

obtained as a brownish solid via the same in situ alkynylation

protocol as described in the synthesis of 2a, using compound 24

(58 mg, 0.033 mmol), C₆₀(130 mg, 0.181 mmol), LHMDS

(0.18 mL, 1 M, 0.18 mmol), and dry THF (150 mL): IR (KBr)

2922, 2852, 2192, 2117, 2077, 1653, 1603, 1541, 1506, 1496 cm^-1

;

¹H NMR (CDCl₃/CS₂, 500 MHz) δ 7.29 (s, 2H), 7.19 (s, 2H), 7.13

(s, 2H), 7.03 (s, 2H), 7.01 (s, 2H), 4.17-4.01 (m, 16H), 1.97-1.82

(m, 16H), 1.70-1.49 (m, 16H), 1.40-1.20 (m, 96H), 0.95-0.82

(m, 24H); ¹³C NMR (CDCl₃/CS₂, 125 MHz) δ 156.7, 155.0,

154.1, 153.7, 152.0, 151.9, 148.1, 147.9, 147.2, 146.9, 146.7, 146.3,

146.0, 145.9, 145.2, 145.0, 143.7, 143.5, 143.10, 143.08, 142.63,

142.55, 142.50, 142.4, 142.2, 141.88, 141.81, 140.9, 140.8, 136.6,

135.7, 118.6, 117.7, 117.4, 116.9, 115.2, 113.7, 111.5, 98.2, 93.2,

92.0, 80.7, 80.0, 75.4, 70.3, 70.2, 70.1, 70.0, 69.3, 65.2, 62.4, 56.0,

32.4, 30.4, 30.3, 30.15, 30.09, 30.04, 29.9, 29.8, 29.7, 29.6, 27.0,

26.5, 26.4, 23.2, 23.1 14.59, 14.56; HRMS (MALDI-TOF) calcd

for C₂₄₀H₁₇₈O₈3187.3522, found 3187.8099 [M]^þ.

(71) Zhao, Y.; MacDonald, R.; Tykwinski, R. R. J. Org. Chem. 2002, 67,

2805–2812.

1510 J. Org. Chem. Vol. 75, No. 5, 2010

Zhou and Zhao

JOCArticle

Compound 4. Compound 4 (6.00 mg, 0.0025 mmol, 5%) was

obtained as a brownish unstable solid via the same in situ

alkynylation protocol as described in the synthesis of 2a, using

compound 28 (50 mg, 0.052 mmol), C₆₀(185 mg, 0.257 mmol),

LHMDS (0.26 mL, 1 M, 0.26 mmol), and dry THF (180 mL): ¹H

NMR (CDCl₃/CS₂, 500 MHz) δ 7.16 (s, 2H), 7.10 (s, 2H), 7.01

(s, 2H), 4.09-4.05 (m, 8H), 1.93-1.84 (m, 8H,), 1.65-1.60 (m,

4H), 1.54-1.50 (m, 4H), 1.29-1.19 (m, 48H), 0.90-0.81 (m,

12H); HRMS (MALDI-TOF) calcd for C₁₈₈H₉₀O₄2410.6992,

found 2410.6839 [M]^þ.

Compound 5a. Compound 5a (11 mg, 0.0017 mmol, 20%) was

obtained as a brownish solid via the same in situ alkynylation

protocol as described in the synthesis of 2a, using compound

47 (30 mg, 0.0083 mmol), C₆₀(60 mg, 0.083 mmol), LHMDS

(0.10 mL, 1 M, 0.10 mmol), and dry THF (120 mL): IR (KBr)

2922, 2851, 2211, 2150, 1632, 1576, 1504, 1464 cm^-1; ¹H NMR

(CDCl₃/CS₂, 500 MHz) δ 7.73 (s, 2H), 7.68 (s, 4H), 7.30 (s, 4H),

7.20 (s, 4H), 7.16 (s, 4H), 7.09 (s, 4H), 7.06 (s, 4H), 4.17-4.01 (m,

32H), 1.93-1.87 (m, 32H), 1.70-1.54 (m, 32H), 1.42-1.20 (m,

192H), 0.91-0.81 (m, 48H); ¹³C NMR (CDCl₃/CS₂, 125 MHz)

δ 155.0, 154.3, 154.1, 154.0, 152.1, 152.0, 148.2, 147.9, 147.2,

146.9, 146.8, 146.3, 146.23, 146.17, 146.0, 145.9, 145.2, 145.0,

143.7, 143.14, 143.11, 142.7, 142.6, 142.53, 142.44, 142.22,

142.15, 140.9, 140.8, 136.6, 135.7, 135.1, 125.1, 122.9, 117.9,

117.7, 117.6, 117.4, 115.6, 115.4, 113.9, 113.5, 98.1, 93.4, 92.4,

92.2, 88.4, 80.9, 70.3, 70.2, 70.1, 70.0, 62.5, 56.0, 32.5, 30.5, 30.4,

30.3, 30.2, 30.1, 30.0, 27.1, 26.8, 26.6, 23.3, 14.7; HRMS

CuI (17 mg, 0.091 mmol), and Et₃N (15 mL) were added to THF

(15 mL). The solution was bubbled with N₂at rt for 5 min and then

stirred at rt under N₂protection for 4 h. After the reaction was

complete as checked by TLC analysis, the solvent was removed by

rotary evaporation. To the residue obtained was added CHCl₃.

The mixture was filtered through a MgSO₄pad. It was then

sequentially washed with aq HCl (10%) and brine. The organic

layer was dried over MgSO₄and concentrated under vacuum. The

crude product was then purified by silica flash column chroma-

tography (hexanes/CH₂Cl₂, 10:1) to yield compound 9 (367 mg,

0.360 mmol, 81%) as a yellow solid: mp 119-120 °C; IR (KBr)

2923, 2901, 2869, 2850, 2157, 1499, 1469 cm^-1; ¹H NMR (CDCl₃,

500 MHz) δ 6.92 (s, 2H), 6.91 (s, 2H), 3.97 (t, J = 7.2 Hz, 4H),

3.94 (t, J = 6.5 Hz, 4H), 1.82-1.77 (m, 8H), 1.51-1.45 (m, 8H),

1.34-1.28 (m, 48 H), 0.88 (t, J = 7.1 Hz, 6H), 0.86 (t, J = 7.1 Hz,

6H), 0.26 (s, 18H); ¹³C NMR (CDCl₃, 125 MHz) δ 155.3, 154.4,

118.0, 117.7, 115.2, 113.2, 101.4, 101.3, 79.8, 79.7, 70.1, 69.9, 32.3,

30.0, 29.9, 29.8, 29.6, 29.4, 26.4, 26.3, 23.1, 14.5, 0.4; HRMS

(MALDI-TOF) calcd for C₆₆H₁₀₆O₄Si₂1018.7630, found

1019.1772 [M]^þ.

1,4-Bis(2,5-bis(decyloxy)-4-ethynylphenyl)buta-1,3-diyne (10).

To a solution of compound 9 (367 mg, 0.360 mmol) in 1:1 MeOH/

THF (20 mL) was added K₂CO₃(50 mg, 0.036 mmol). After

being stirred at rt for 1 h, the reaction solvent was removed by

rotary evaporation. The residue was dissolved in CHCl₃and

sequentially washed with aq HCl (10%) and brine. The organic

layer was dried over MgSO₄. Filtration to remove MgSO₄

followed by evaporation under vacuum afforded 10 as a yellow

solid (302 mg, 0.345 mmol, 96%): mp 110-111 °C; IR (KBr)

3283, 2923, 2850, 2140, 2105, 1500, 1469 cm^-1; ¹H NMR (CDCl₃,

500 MHz) δ 6.96 (s, 2H), 6.95 (s, 2H), 3.971 (t, J = 6.4 Hz, 4H),

3.965 (t, J = 7.1 Hz, 4H), 3.35 (s, 2H), 1.84-1.77 (m, 8H),

1.50-1.41 (m, 8H), 1.36-1.25 (m, 48 H), 0.88 (t, J = 7.1 Hz, 6H),

0.86 (t, J = 6.0 Hz, 6H); ¹³C NMR (CDCl₃, 125 MHz) δ 155.2,

154.4, 118.3, 118.1, 114.2, 113.6, 83.3, 80.3, 79.6, 70.2, 70.1, 32.3,

30.01, 29.99, 29.89, 29.5, 26.3, 23.1, 14.5; HRMS (MALDI-TOF)

calcd for C₆₀H₉₀O₄874.6839, found 875.6830 [M þ H]^þ.

(MALDI-TOF) calcd for

C₄₈₈H₃₆₂O₁₆6476.7513, found

6476.2834 [M]^þ.

1,4-Bis(decyloxy)-2-ethynyl-5-iodobenzene (7). To a solution

of compound 6 (472 mg, 0.771 mmol) in 1:1 MeOH/THF

(20 mL) was added K₂CO₃(50 mg, 0.36 mmol). After being

stirred at rt for 2 h, the reaction solvent was evaporated in vacuo.

To the residue were added hexanes and aq HCl (1 M). The

organic layer was isolated, washed with brine, and dried over

MgSO₄. Filtration to remove MgSO₄followed by evaporation

under vacuum afforded deprotected terminal alkyne 7 (412 mg,

0.762 mmol, 99%): mp 50-51 °C; IR (KBr) 3289, 2955, 2921,

2850, 2107, 1588, 1495, 1467 cm^-1; ¹H NMR (CDCl₃, 500 MHz)

δ 7.29 (s, 1H), 6.87 (s, 1H), 3.96 (t, J = 6.4 Hz, 2H), 3.93 (t, J =

6.4 Hz, 2H), 3.29 (s, 1H), 1.81-1.78 (m, 4H), 1.54-1.44 (m, 4H),

1.36-1.25 (m, 24 H), 0.90-0.87 (m, 6H); ¹³C NMR (CDCl₃,

125 MHz) δ 155.3, 152.2, 124.3, 117.2, 112.7, 88.8, 82.2, 80.1,

70.6, 70.4, 32.3, 30.0, 29.8, 29.58, 29.57, 26.6, 26.5, 26.3, 23.1,

14.5; MS (APCI) calcd for C₂₈H₄₅IO₂540.3, found 541.3 [M þ H]^þ.

1,4-Bis(2,5-bis(decyloxy)-4-iodophenyl)buta-1,3-diyne (8).

Compound 7 (215 mg, 0.387 mmol) was dissolved in acetone

(10 mL), and then Hay catalyst (5 mL) was added. The mixture

was stirred at rt under exposure to air for 36 h. When TLC

analysis showed no starting material present, acetone was

evaporated in vacuo, and CHCl₃(10 mL) was added. The

resulting content was washed with aq HCl (1 M), satd NaHCO₃,

and brine sequentially. The organic layer was dried over MgSO₄

and evaporated in vacuo to give the crude product. The crude

product was purified by silica flash column chromato-

graphy (hexanes/CH₂Cl₂, 85:15) to yield compound 8 (160 mg,

0.146 mmol, 75%) as a pale yellow solid: mp 104-105 °C;

1,4-Bis(4-((2,5-bis(decyloxy)-4-((triisopropylsilyl)ethynyl)-

phenyl)ethynyl)-2,5-bis(decyloxy)phenyl)buta-1,3-diyne (12). To a

solution of 11 (226 mg, 0.224 mmol) in acetone (30 mL) was

added Hay catalyst (5 mL). The mixture was stirred at rt under

exposure to air overnight. The reaction solvent was evaporated in

vacuo. To the residue was added CHCl₃. The resulting content

was washed with aq HCl (1 M), satd NaHCO₃, and brine

sequentially. The organic layer was dried over MgSO₄and

evaporated in vacuo to give the crude product, which was further

purified by silica flash column chromatography (hexanes/

CH₂Cl₂, 3:1) to give compound 12 (96 mg, 0.048 mmol, 43%)

as a yellow solid: mp 72-73 °C; IR (KBr) 2924, 2852, 2146, 1622,

1497, 1470 cm^-1; ¹H NMR(CDCl₃, 500 MHz) δ 6.99 (s, 4H), 6.94

(s, 4H),4.03-3.94 (m, 16H), 1.86-1.77 (m, 16H), 1.50 (m, 16H),

1.36-1.25 (m, 96 H), 1.15 (s, 42H), 0.89-0.85 (m, 24H); ¹³C

NMR (CDCl₃, 125 MHz) δ 154.8, 154.2, 153.8, 118.4, 118.3,

117.5, 117.0, 115.9, 114.64, 114.61, 113.0, 103.4, 97.0, 92.7, 91.6,

80.0, 79.8, 70.3, 70.2, 69.7, 32.3, 30.09, 30.05, 30.00, 29.93, 29.88,

29.8, 29.7, 29.6, 26.6, 26.4, 23.1, 19.1, 14.5, 11.8; HRMS

(MALDI-TOF) calcd for C₁₃₄H₂₁₈O₈Si₂2011.6190, found

2012.2954 [M þ H]^þ.

IR (KBr) 2918, 2847, 2149, 1494 cm^-^{1 1}H NMR (CDCl₃,

;

500 MHz) δ 7.29 (s, 2H), 6.87 (s, 2H), 3.96 (t, J = 6.0 Hz,

4H), 3.93 (t, J = 6.8 Hz, 4H), 1.83-1.77 (m, 8H), 1.50-1.44

(m, 8H), 1.36-1.25 (m, 48 H), 0.88 (t, J = 6.5 Hz, 6H), 0.86 (t,

J = 6.5 Hz, 6H); ¹³C NMR (CDCl₃, 125 MHz) δ 156.0, 152.2,

124.4, 117.0, 112.7, 89.6, 79.2, 79.0, 70.54, 70.50, 32.3, 30.01,

29.99, 29.7, 29.5, 26.5, 26.3, 23.1, 14.5; HRMS (MALDI-TOF)

calcd for C₅₆H₈₈I₂O₄1078.4772, found 1078.4464 [M]^þ.

1,4-Bis(2,5-bis(decyloxy)-4-((trimethylsilyl)ethynyl)phenyl)buta-

1,3diyne (9). Compound 8 (481 mg, 0.446 mmol), trimethylsilyla-

cetylene (0.32 mL, 1.37 mmol), PdCl₂(PPh₃)₂(31 mg, 0.044 mmol),

1,4-Bis(4-((2,5-bis(decyloxy)-4-ethynylphenyl)ethynyl)-2,5-bis-

(decyloxy)phenyl)buta-1,3-diyne (13). To a solution of compound

12 (303 mg, 0.154 mmol) in THF (20 mL) was added TBAF

(0.1 mL, 1 M, 0.1 mmol). The mixture was stirred at rt for 12 h.

The reactionsolvent wasevaporated in vacuo. To the residue was

added CHCl₃. The resulting content was washed with aq HCl

(1 M), satd NaHCO₃, and brine sequentially. The organic layer

was dried over MgSO₄and evaporated in vacuo to give the crude

product, which was further purified by silica flash column

chromatography (hexanes/CH₂Cl₂, 7:3) to yield compound 13

J. Org. Chem. Vol. 75, No. 5, 2010 1511

Zhou and Zhao

JOCArticle

(211 mg, 0.124 mmol, 81%) as a yellow solid: mp 93-94 °C; IR

(KBr) 3315, 2925, 2850, 2195, 2136, 2106, 1639, 1618, 1497, 1469

cm^-1; ¹H NMR (CDCl₃, 500 MHz) δ 7.02 (s, 6H), 7.01 (s, 2H),

4.06-3.99 (m, 16H), 3.38 (s, 2H), 1.89-1.80 (m, 16H), 1.54-1.46

(m, 16H), 1.40-1.26 (m, 96H), 0.93-0.89 (m, 24H); ¹³C NMR

(CDCl₃, 125 MHz) δ 155.4, 154.6, 153.8, 118.4, 118.3, 117.51,

117.46, 115.8, 115.3, 113.2, 113.1, 92.3, 91.8, 82.8, 80.5, 80.0,

79.8, 70.2, 70.0, 32.3, 30.11, 30.05, 30.03, 30.00, 29.9, 29.73,

29.71, 29.64, 29.62, 26.4, 23.1, 14.5; HRMS (MALDI-TOF)

calcd for C₁₁₆H₁₇₈O₈1699.3522, found 1699.4987 [M]^þ.

6.90 (s, 1H), 6.89 (s, 1H), 3.97 (t, J = 7.1 Hz, 2H), 3.92 (t, J =

5.8 Hz, 2H), 1.82-1.72 (m, 4H), 1.50-1.42 (m, 4H), 1.40-1.24

(m, 24 H), 1.14 (s, 21H), 0.89 (t, J = 7.1 Hz, 6H), 0.23 (s, 9H);

¹³C NMR (CDCl₃, 125 MHz) δ 155.5, 154.5, 118.1, 117.8,

115.7, 112.4, 103.1, 97.9, 92.2, 88.5, 79.4, 73.9, 70.3, 69.7, 32.3,

32.2, 30.3, 30.1, 30.0, 29.81, 29.78, 29.6, 29.0, 26.6,26.4, 26.2,

23.1, 19.4, 19.2, 19.0, 18.9, 18.6, 14.5, 11.8, 0.1; HRMS

(MALDI-TOF) calcd for C₄₄H₇₄O₂Si₂690.5227, found

691.2629 [M þ H]^þ.

1,8-Bis(2,5-bis(decyloxy)-4-((triisopropylsilyl)ethynyl)phenyl)-

octa-1,3,5,7-tetrayne (19). To a solution of compound 17

(277 mg, 0.401 mmol) in 1:1 MeOH/THF (8 mL) was added

K₂CO₃(20 mg, 0.14 mmol). After being stirred at rt for 2 h, the

reaction mixture was quenched with water (10 mL) and then

extracted with hexanes (30 mL). The organic layer was isolated,

washed with brine, and dried over MgSO₄. Filtration to remove

MgSO₄followed by concentration under vacuum afforded a

dark solid, which was immediately transferred into a flask

containing acetone (6 mL) and Hay catalyst (2 mL). The mixture

was stirred at rt under exposure to air overnight and then

was briefly worked up to afford the crude product. Silica flash

column chromatography (hexanes/CH₂Cl₂, 9:1) gave com-

pound 19 (132 mg, 0.107 mmol, 53%) as a brownish solid: mp

((2,5-Bis(decyloxy)-4-iodophenyl)buta-1,3-diynyl)trimethylsilane

(14). To a flask containing compound 6 (849 mg, 1.57 mmol),

trimethylsilylacetylene (0.70 mL, 4.9 mmol), and acetone (20 mL)

was added Hay catalyst (2 mL). The mixture was stirred at rt under

exposure to air for 2 h. When TLC analysis showed no starting

material present, hexanes (40 mL) was added. The resulting

content was washed with aq HCl (1 M), satd NaHCO₃, and brine

sequentially. The organic layer was dried over MgSO₄and evapo-

rated in vacuo to give a dark yellow solid. The crude product was

purified by silica flash column chromatography (hexanes/CH₂Cl₂,

5:1) to yield compound 14 (675 mg, 1.06 mmol, 68%) as a yellow

solid: mp 41-42 °C; IR (neat) 2922, 2851, 2208, 2104, 1496 cm^-1

;

¹H NMR (CDCl₃, 500 MHz) δ 7.31 (s, 1H), 6.87 (s, 1H), 3.98 (t,

J = 7.1 Hz, 2H), 3.94 (t, J = 6.5 Hz, 2H), 1.82 (m, 4H), 1.50 (m,

4H), 1.40-1.22 (m, 24 H), 0.92 (t, J = 5.9 Hz, 6H), 0.26 (s, 9H);

¹³C NMR (CDCl₃, 125 MHz) δ 156.3, 152.1, 124.4, 117.3, 112.1,

92.0, 89.8, 88.4, 79.0, 73.5, 70.50, 70.47, 32.3, 30.0, 29.7, 29.5, 26.5,

26.3, 23.1, 14.5, 0.1; MS (APCI) Calcd for C₃₃H₅₃IO₂Si 636.7,

found 636.3 [M]^þ.

58-59 °C; IR (neat) 2921, 2852, 2193, 2150, 1498 cm^-^{1 1}H

;

NMR (CDCl₃, 500 MHz) δ 6.89 (s, 4H), 3.97 (t, J = 6.6 Hz, 4H),

3.91 (t, J = 6.6 Hz, 4H), 1.83-1.74 (m, 8H), 1.51-1.44 (m, 8H),

1.40-1.24 (m, 48 H), 1.14 (s, 42H), 0.89 (m, 12H); ¹³C NMR

(CDCl₃, 125 MHz) δ 156.4, 154.5, 117.9, 117.7, 116.6, 111.4,

103.1, 98.7, 79.7, 75.3, 70.2, 69.7, 69.1, 65.0, 32.4, 32.3, 30.4, 30.0,

29.9, 29.8, 29.6, 29.0, 26.4, 26.2, 23.2, 23.1, 19.4, 19.2, 19.1, 19.0,

18.9, 18.7, 14.5, 11.8; HRMS (MALDI-TOF) calcd for

C₈₂H₁₃₀O₄Si₂1234.9508, found 1235.1084 [M]^þ.

1,8-Bis(2,5-bis(decyloxy)-4-iodophenyl)octa-1,3,5,7-tetrayne

(15). To a solution of compound 14 (277 mg, 0.401 mmol) in 1:1

MeOH/THF (8 mL) was added K₂CO₃(20 mg, 0.14 mmol).

After being stirred at rt for 2 h, the reaction mixture was

quenched with water (10 mL) and then extracted with hexanes

(30 mL). The organic layer was isolated, washed with brine,

and dried over MgSO₄. Filtration to remove MgSO₄followed

by concentration under vacuum afforded a dark solid, which

was immediately transferred into a flask containing acetone

(6 mL) and Hay catalyst (2 mL). The mixture was stirred at rt

under exposure to air overnight and then was briefly worked up

to afford the crude product, which was further purified by silica

flash column chromatography (hexanes/CH₂Cl₂, 9:1) to give

compound 15 (132 mg, 0.107 mmol, 53%) as a yellow solid: mp

1,8-Bis(2,5-bis(decyloxy)-4-ethynylphenyl)octa-1,3,5,7-tetrayne

(20). To a solution of compound 19 (190 mg, 0.154 mmol) in THF

(4 mL) was added TBAF (0.09 mL, 1 M, 0.09 mmol). The mixture

was stirred at rt for 10 min. The solvent was removed by rotary

evaporation. To the residue were added CHCl₃andaqHCl (1 M).

The organic layer was isolated, washed with brine, and dried over

MgSO₄. Filtration to remove MgSO₄followed by evaporation

under vacuum afforded the crude product, which was further

purified by silica flash column chromatography (hexanes/

CH₂Cl₂, 1:9) to yield compound 20 (110 mg, 0.119 mmol, 77%)

as a brownish waxy solid: IR (KBr) 3314, 3293, 2916, 2850, 2195,

1604, 1530 cm^-1; ¹H NMR (CDCl₃, 500 MHz) δ 6.94 (s, 2H), 6.93

(s, 2H), 3.96 (t, J = 6.4 Hz, 8H), 3.38 (s, 2H), 1.82-1.76 (m, 8H),

1.50-1.42 (m, 8H), 1.40-1.22 (m, 48H), 0.88 (m, 12H); ¹³CNMR

(CDCl₃, 125 MHz) δ 156.4, 154.3, 118.3, 118.1, 115.2, 112.0, 83.9,

80.1, 79.8, 74.9, 70.2, 70.1, 69.1, 64.9, 32.35, 32.33, 30.0, 29.79,

29.75, 29.6, 29.5, 29.3, 29.1, 26.44, 26.29, 23.0, 22.9, 14.56, 14.53;

HRMS (MALDI-TOF) calcd for C₆₄H₉₀O₄922.6839, found

922.7046 [M]^þ.

1

70-71 °C; IR (neat) 2916, 2849, 2198, 1494 cm^-1; H NMR

(CDCl₃, 500 MHz) δ 7.27 (s, 2H), 6.82 (s, 2H), 3.93 (t, J =

6.3 Hz, 4H), 3.90 (t, J = 6.3 Hz, 4H), 1.81-1.75 (m, 8H),

1.51-1.43 (m, 8H), 1.35-1.29 (m, 48 H), 0.89-0.87 (m, 12H);

¹³C NMR (CDCl₃, 125 MHz) δ 157.1, 152.2, 124.2, 117.1,

111.1, 91.1, 79.3, 74.9, 70.5, 70.4, 68.8, 64.8, 32.40, 32.37, 30.06,

30.02, 29.83, 29.78, 29.76, 29.6, 29.5, 26.5, 26.4, 23.18, 23.15,

14.69, 14.58; HRMS (MALDI-TOF) calcd for C₆₀H₈₈I₂O₄

1126.4772, found 1126.1290 [M]^þ.

((4-((2,5-Bis(decyloxy)-4-((triisopropylsilyl)ethynyl)phenyl)-

ethynyl)-2,5-bis(decyloxy)phenyl)buta-1,3-diynyl)trimethylsilane

(21). To a solution of 11 (590 mg, 0.586 mmol) and trimethylsilyl-

acetylene (1.02 mL, 3.52 mmol) in acetone (20 mL) was added

Hay catalyst (5 mL). The mixture was stirred at rt under

exposure to air overnight. The reaction solvent was evaporated

in vacuo. To the residue was added CHCl₃. The resulting content

was washed with aq HCl (1 M), satd NaHCO₃, and brine

sequentially. The organic layer was dried over MgSO₄and

evaporated invacuoto give the crude product. Silicaflash column

chromatography (hexanes/CH₂Cl₂, 4:1) gave compound 21

(513 mg, 0.465 mmol, 79%) as a yellow solid: mp 70-71 °C; IR

((2,5-Bis(decyloxy)-4-((triisopropylsilyl)ethynyl)phenyl)buta-

1,3-diynyl)trimethylsilane (17). Compound 14 (675 mg, 1.06

mmol), triisopropylsilylacetyelene (0.28 mL, 1.2 mmol), PdCl₂-

(PPh₃)₂(37 mg, 0.053 mmol), CuI (30 mg, 0.16 mmol), and

Et₃N (3 mL) were added to THF (20 mL). The solution was

bubbled with N₂at rt for 5 min and then stirred at 45 °C under

N₂protection overnight. After the reaction was complete as

checked by TLC analysis, the solvent was removed by rotary

evaporation. To the residue were added CHCl₃and aq HCl

(1 M). The organic layer was isolated, washed with brine, and

dried over MgSO₄. Filtration to remove MgSO₄followed by

evaporation under vacuum afforded the crude product which

was then purified by silica flash column chromatography

(hexanes/CH₂Cl₂10:1) to yield compound 17 (630 mg, 0.911

mmol, 86%) as a pale yellowish wax: IR (neat) 2924, 2857,

(KBr) 2923, 2852, 2196, 2150, 2100, 1622, 1497, 1468, 1389 cm^-1

;

¹H NMR (CDCl₃, 500 MHz) δ 6.96 (s, 1H), 6.93 (s, 3H),

4.02-3.93 (m, 8H), 1.83-1.77 (m, 8H), 1.50-1.47 (m, 8H),

1.34-1.24 (m, 48 H), 1.15 (s, 21H), 0.90-0.86 (m, 12H), 0.23

(s, 9H); ¹³C NMR (CDCl₃, 125 MHz) δ 155.7, 154.8, 153.8,

1

2201, 2151, 2100, 1497 cm^-1; H NMR (CDCl₃, 500 MHz) δ

1512 J. Org. Chem. Vol. 75, No. 5, 2010

Zhou and Zhao

JOCArticle

153.7, 118.5, 118.4, 117.4, 116.9, 116.1, 114.7, 112.3, 103.5,

97.0, 92.8, 92.1, 91.5, 88.6, 79.6, 73.9, 70.3, 70.1, 69.6, 32.4,

30.1, 29.98, 29.89, 29.8, 29.7, 29.6, 26.7, 26.4, 23.1, 19.1, 14.5,

11.8, 0.1; MS (APCI) calcd for C₇₂H₁₁₈O₄Si₂1102.9, found

1103.7 [M þ H]^þ.

CHCl₃. The resulting mixture was washed with aq HCl (1 M),

satd NaHCO₃, and brine sequentially. The organic layer was

dried over MgSO₄and evaporated in vacuo to give a brown

wax. The crude product was purified by silica flash column

chromatography (hexanes/CH₂Cl₂, 95:5) to yield compound

25 (930 mg, 1.30 mmol, 90% based on the consumption of 17)

as a brown wax: IR (KBr) 2924, 2854, 2170, 2152, 2077, 1450,

1469 cm^-1; ¹H NMR (CDCl₃, 500 MHz) δ 6.88 (s, 2H), 3.96 (t,

J = 6.6 Hz, 2H), 3.90 (t, J = 6.6 Hz, 2H), 1.78-1.75 (m, 4H),

1.47-1.45 (m, 4H), 1.29-1.27 (m, 24 H),1.13 (s, 21H),

0.90-0.87 (m, 6H), 0.22 (s, 9H); ¹³C NMR (CDCl₃, 125 MHz)

δ 156.0, 154.3, 117.7, 117.5, 116.2, 111.4, 102.8, 98.2, 89.7, 88.5,

79.3, 73.9, 70.0, 69.5, 68.3, 62.0, 32.14, 32.13, 29.84, 29.81, 29.7,

29.60, 29.58, 29.55, 29.4, 26.4, 26.2, 22.94, 22.91, 18.9, 14.36,

14.33, 11.6, 0.27; HRMS (MALDI-TOF) calcd for C₄₆H₇₄O₂Si₂

714.5227, found 715.4420 [M þ H]^þ.

1,8-Bis(4-((2,5-bis(decyloxy)-4-((triisopropylsilyl)ethynyl)-

phenyl)ethynyl)-2,5-bis(decyloxy)phenyl)octa-1,3,5,7-tetrayne (23).

To a solution of compound 21 (513 mg, 0.465 mmol) in 1:1 MeOH/

THF (30 mL) was added K₂CO₃(100 mg, 0.72 mmol). After being

stirred at rt for 2 h, the reaction solvent was evaporated in vacuo.

To the residue were added CHCl₃and then aq HCl (1 M). The

organic layer was isolated, washed with brine, and dried over

MgSO₄. Filtration to remove MgSO₄followed by concentration

under vacuum afforded a dark solid, which was immediately

transferred into a flask containing acetone (20 mL) and Hay

catalyst (5 mL). The mixture was stirred at rt under exposure to

air for 12 h. The reaction solvent was evaporated in vacuo. To the

residue was added CHCl₃. The resulting content was washed with

aq HCl (1 M), satd NaHCO₃, and brine sequentially. The organic

layer was dried over MgSO₄and evaporated in vacuo to give the

crude product. Silica flash column chromatography (hexanes/

CH₂Cl₂, 4:1) gave compound 23 (405 mg, 0.196 mmol, 85%) as

a brownish solid: mp 71-72 °C; IR (KBr) 2923, 2853, 2194, 2149,

1623, 1499, 1468, 1423, 1388 cm^-1; ¹H NMR (CDCl₃, 500 MHz) δ

6.98 (s, 2H), 6.97 (s, 2H), 6.95 (s, 4H), 4.04-3.94 (m, 16H),

1.85-1.81 (m, 16H), 1.51-1.48 (m, 16H), 1.37-1.25 (m, 96 H),

1.16 (s, 42H), 0.92-0.87 (m, 24H); ¹³C NMR(CDCl₃, 125 MHz) δ

156.7, 154.8, 153.8, 153.7, 118.5, 118.3, 117.2, 117.0, 116.9, 114.8,

114.5, 111.3, 103.4, 97.1, 93.4, 91.4, 79.9, 75.4, 70.3, 70.14, 70.08,

69.7, 69.2, 65.1, 32.4, 32.3, 30.1, 29.88 (br), 29.83, 29.81, 29.75,

29.71, 29.68, 29.66, 29.6 (br), 29.5, 29.3, 26.7, 26.44, 26.38, 23.13,

23.09, 19.2, 14.53, 14.49, 11.8; HRMS (MALDI-TOF) calcd for

1,12-Bis(2,5-bis(decyloxy)-4-((triisopropylsilyl)ethynyl)phenyl)-

dodeca-1,3,5,7,9,11-hexayne (27). To a solution of compound 25

(930 mg, 1.30 mmol) in 1:1 MeOH/THF (40 mL) was added

K₂CO₃(200 mg, 1.40 mmol). After being stirred at rt for 1.5 h, the

reaction solvent was evaporated in vacuo. To the residue were

added CHCl₃and then aq HCl (1 M). The organic layer was

isolated, washed with brine, and dried over MgSO₄. Filtration

to remove MgSO₄followed by concentration under vacuum

afforded a dark solid, which was immediately transferred into a

flask containing acetone (80 mL) and Hay catalyst (10 mL). The

mixturewas stirredat rtunder exposuretoairfor 2 h. The reaction

solvent was evaporated in vacuo. To the residue was added

CHCl₃. The resulting mixture was washed with aq HCl (1 M),

satd NaHCO₃, and brine sequentially. The organic layer was

dried over MgSO₄and evaporated in vacuo to give the crude

product. The crude product was further purified by silica flash

column chromatography (hexanes/CH₂Cl₂, 95:5) to give com-

pound 27 (325 mg, 0.253 mmol, 39%) as a brownish wax: IR

(KBr) 2925, 2859, 2153, 2046, 1499, 1466, 1416 cm^-1; ¹H NMR

(CDCl₃, 500 MHz) δ 6.89 (s, 2H),6.88 (s, 2H), 3.97 (t, J = 6.4 Hz,

4H), 3.92 (t, J = 6.4 Hz, 4H), 1.78-1.77 (m, 8H), 1.47-1.45 (m,

C

₁₃₈H₂₁₈O₈Si₂2059.6190, found 2060.3330 [M þ H]^þ.

1,8-Bis(4-((2,5-bis(decyloxy)-4-ethynylphenyl)ethynyl)-2,5-bis-

(decyloxy)phenyl)octa-1,3,5,7-tetrayne (24). To a solution of

compound 23 (405 mg, 0.196 mmol) in THF (25 mL) was added

TBAF (0.1 mL, 1 M, 0.1 mmol). The mixture was stirred at rt for

3 h. The reaction solvent was evaporated in vacuo. To the residue

was added CHCl₃. The resulting content was washed with aq

HCl (1 M), satd NaHCO₃, and brine sequentially. The organic

layer was dried over MgSO₄and evaporated in vacuo to give the

crude product, which was further purified by silica flash column

chromatography (hexanes/CH₂Cl₂, 3:1) to yield compound 24

(287 mg, 0.164 mmol, 84%) as a brownish solid: mp 92-93 °C;

IR (KBr) 3314, 2924, 2851, 2194, 2106, 1627, 1499, 1468, 1422,

1386 cm^-1; ¹H NMR (CDCl₃, 500 MHz) δ 6.973 (s, 2H), 6.969 (s,

2H), 6.961 (s, 4H), 4.01-3.96 (m, 16H), 3.34 (s, 2H), 1.85-1.78

(m, 16H), 1.52-1.44 (m, 16H), 1.36-1.24 (m, 96H), 0.90-0.86

(m, 24H); ¹³C NMR (CDCl₃, 125 MHz) δ 156.63, 154.58, 153.8,

153.7, 118.5, 118.4, 117.5, 117.3, 116.9, 115.1, 113.4, 111.4, 93.0,

91.6, 82.9, 80.4, 79.9, 75.3, 70.2, 70.1, 70.0, 69.2, 65.1, 33.3, 30.09,

30.05, 29.99, 29.8, 29.7, 29.6, 29.5, 29.4, 26.4, 23.1, 14.5; HRMS

8H), 1.33-1.27 (m, 48 H), 1.13 (s, 42H), 0.91-0.87 (m, 12H); ¹³

C

NMR (CDCl₃, 125 MHz) δ 156.9, 154.5, 117.9, 117.8, 117.1,

110.8, 102.9, 99.1, 79.5, 74.9, 70.2, 69.7, 69.1, 65.8, 64.5, 63.4, 32.5,

32.3, 30.0, 29.97, 29.87, 29.79, 29.75, 29.5, 26.5, 26.4, 23.13, 23.09,

19.2, 19.0, 14.54, 14.53, 11.8; HRMS (MALDI-TOF) calcd for

C₈₂H₁₃₀O₄Si₂1282.9508, found 1284.1663 [M þH]^þ.

(3,5-Diiodophenyl)methanol (31). To a solution of compound

30 (1.00 g, 2.58 mmol) in dry CH₂Cl₂(20 mL) was added DIBAL

(8.67 mL, 1 M in THF, 8.67 mmol) at 0 °C in two portions

during a period of 4 h. The reaction was treated with aq HCl

(1 M) slowly at 0 °C and then extracted with CH₂Cl₂. The

organic layer was washed with brine, dried over MgSO₄, and

concentrated under vacuum. The residue was purified by silica

flash column chromatography (hexanes/CH₂Cl₂, 4:1) to give 31

(880 mg, 2.45 mmol, 95%) as a white solid: mp 147-148 °C; ¹H

NMR (CDCl₃, 500 MHz) δ 7.98 (s, 1H), 7.69 (s, 2H), 4.62 (d,

J = 6.6 Hz, 2H), 1.76 (t, J = 5.9 Hz, 1H); ¹³C NMR (CDCl₃,

125 MHz) δ 94.3, 94.1, 91.8, 81.7, 73.8; GC-MS (EI) calcd for

C₇H₆I₂O 360, found 360 (100%) [M]^þ. The characterizations

are consistent with the literature data.⁷²

(MALDI-TOF) calcd for

C₁₂₀H₁₇₈O₈1747.3622, found

1748.8991 [M þ H]^þ.

((2,5-Bis(decyloxy)-4-((triisopropylsilyl)ethynyl)phenyl)hexa-

1,3,5-triynyl)trimethylsilane (25). To a solution of compound 17

(1.00 g, 1.45 mmol) in 1:1 MeOH/THF (60 mL) was added

K₂CO₃(500 mg, 3.62 mmol). After being stirred at rt for 2 h, the

reaction solvent was evaporated in vacuo. To the residue were

added hexanes and aq HCl (1 M). The organic layer was

isolated, washed with brine, and dried over MgSO₄. Filtration

to remove MgSO₄followed by evaporation under vacuum

afforded the deprotected terminal alkyne, which was immedi-

ately transferred into a flask containing trimethylsilylacetylene

(15 mL, 0.11 mol), acetone (90 mL), and Hay catalyst (10 mL).

The mixture was stirred at rt under exposure to air for 6 h. When

TLC analysis showed no starting material present, the reaction

solvent was evaporated in vacuo. To the residue was added

3,5-Diiodobenzaldehyde (32). To a stirred solution of PCC

(1.37 g, 6.34 mmol) in CH₂Cl₂(20 mL) was added a solution of

31 (1.14 g, 3.17 mmol) in CH₂Cl₂(10 mL). The reaction was

stirred at rt for 2 h. The solvent was removed under vacuum,

giving the crude product of 32, which was then purified by silica

flash column chromatography (hexanes/EtOAc, 80:20) to give

compound 32 (1.08 g, 3.02 mmol, 95%) as a white solid: mp

1

133-134 °C; H NMR (CDCl₃, 500 MHz) δ 9.83 (s,1H), 8.29

(72) Shortell, D. B.; Palmer, L. C.; Tour, J. M. Tetrahedron 2001, 57,

9055–9065.

J. Org. Chem. Vol. 75, No. 5, 2010 1513

Zhou and Zhao

JOCArticle

(t, J = 1.3 Hz, 1H), 8.14 (d, J = 1.3 Hz, 2H); ¹³C NMR (CDCl₃,

125 MHz) δ 189.5, 151.0, 139.4, 138.2, 95.7; GC-MS (EI)

calcd for C₇H₄I₂O, 358, found 358 (100%) [M]^þ, 329 (12%)

[M - CHO]^þ. The characterizations are consistent with the

literature data.⁷³

NMR (CDCl₃, 500 MHz) δ 7.67 (s, 2H), 7.62 (d, J = 1.3 Hz, 4H),

6.95 (s, 4H), 6.94 (s, 4H), 4.02(t, J = 6.5 Hz, 8H), 3.97 (t, J =

6.5 Hz, 8H), 1.87-1.76 (m, 16H), 1.57-1.47 (m, 16H), 1.31-1.21

(m, 96 H), 1.53 (s, 84H), 0.89 (t, J = 6.8 Hz, 12H), 0.85 (t, J =

7.0 Hz, 12H); ¹³C NMR (CDCl₃, 125 MHz) δ 154.5, 153.8, 135.1,

134.9, 124.8, 122.6, 118.0, 116.7, 114.8, 113.6, 103.1, 97.0, 92.8,

87.9, 80.6, 74.9, 70.0, 69.5, 32.16, 32.13, 29.9, 29.85, 29.83, 29.7,

29.69, 29.62, 29.6, 26.4, 26.38, 22.9, 18.9, 14.3, 11.6; HRMS

(MALDI-TOF) calcd for C₁₇₂H₂₆₆O₈Si₄2571.9485, found

2573.5731 [M þ H]^þ.

1-(2,2-Dibromovinyl)-3,5-diiodobenzene (33). To a flask filled

with dry CH₂Cl₂(30 mL) were added CBr₄(0.94 g, 2.8 mmol)

and PPh₃(1.49 g, 5.69 mmol). The mixture was stirred at rt for

5 min to produce a red solution. Then a solution of compound 32

(0.68 g, 1.9 mmol) in CH₂Cl₂(15 mL) was added dropwise. The

reaction was stirred overnight. The solvent was removed by

rotary evaporation. The crude product was then purified by

silica flash column chromatography (hexanes/CH₂Cl₂, 95:5),

affording compound 33 (0.91 g, 1.77 mmol, 93%) as a white

solid: mp 58-59 °C; ¹H NMR (CDCl₃, 500 MHz) δ 7.99 (s, 1H),

1,4-Bis(3,5-bis((2,5-bis(decyloxy)-4-ethynylphenyl)ethynyl)-

phenyl)buta-1,3-diyne (38). To a solution of compound 37

(123 mg, 0.0478 mmol) in THF (6 mL) was added TBAF

(0.05 mL, 1 M, 0.05 mmol). The mixture was stirred at rt for

30 min, and the solvent was removed by rotary evaporation.

To the residue were added CHCl₃and aq HCl (1 M). The

organic layer was isolated and washed with brine and dried

over MgSO₄. Filtration to remove MgSO₄followed by eva-

poration under vacuum afforded the crude product, which

was further purified by silica flash column chromatography

(hexanes/CH₂Cl₂, 7:3) to yield compound 38 (68 mg, 0.035

mmol, 73%) as a brownish wax: IR (KBr) 3283, 2923, 2852,

2210, 2104, 1604, 1578, 1533, 1501, 1469, 1420, 1389 cm^-1; ¹H

NMR (CDCl₃, 500 MHz) δ 7.68 (s, 2H), 7.63 (d, J = 1.5 Hz,

4H), 6.99 (s, 4H), 6.98 (s, 4H), 4.01 (t, J = 6.1 Hz, 16H), 3.36 (s,

4H), 1.87-1.80 (m, 16H), 1.57-1.46 (m, 16H), 1.42-1.21 (m,

7.78 (s, 2H), 7.27 (s, 1H); ¹³C NMR (CDCl₃, 125 MHz) δ 144.9,

79

138.7, 136.3, 133.8, 94.9, 93.1; MS (APCI) calcd for C₈H₄

-

Br⁸¹BrI₂, 513.7, found 513.8 [M]^þ.

1-Ethynyl-3,5-diiodobenzene (34). LDA (2.5 mL, 1.8 M in

THF, 4.43 mmol) was slowly added to a solution of 33 (910 mg,

1.77 mmol) in THF (15 mL) at -78 °C. After being stirred at this

temperature for 1 h, the reaction was quenched by addition of

satd aq NH₄Cl solution (10 mL). The mixture was diluted with

hexanes (100 mL), and the organic phase was then washed with

brine, dried over MgSO₄, and concentrated under vacuum. The

crude product was purified by silica flash column chromato-

graphy (hexanes), affording compound 34 (544 mg, 1.54 mmol,

87%) as a white solid: mp 128-129 °C; ¹H NMR (CDCl₃,

500 MHz,) δ 8.03 (s, 1H), 7.78 (s, 2H), 3.17 (s, 1H); ¹³C NMR

(CDCl₃, 125 MHz) δ 145.7, 140.1, 125.8, 94.3, 80.5, 80.0;

GC-MS calcd for C₈H₄I₂354, found 354 (100%) [M]^þ, 227

(23%) [M - I]^þ. The characterizations are consistent with the

literature data.⁷⁴

96 H), 0.89 (t, J = 7.2 Hz, 12H), 0.85 (t, J = 6.6 Hz, 12H); ¹³

C

NMR (CDCl₃, 125 MHz) δ 154.3, 153.9, 135.1, 130.0, 124.7,

122.6, 118.0, 117.2, 114.1, 113.4, 93.0, 87.6, 82.7, 80.5, 80.1,

74.9, 69.9, 32.1, 29.9, 29.79, 29.77, 29.66, 29.57, 29.55, 29.53,

29.4, 26.3, 26.1, 22.9, 14.3; HRMS (MALDI-TOF) calcd for

C

₁₃₆H₁₈₆O₈1947.4148, found 1947.1021 [M]^þ.

((3,5-Diiodophenyl)ethynyl)trimethylsilane (39). To a solution

1,4-Bis(3,5-diiodophenyl)buta-1,3-diyne (35). To a solution of

34 (70 mg, 0.20 mmol) in acetone/CH₂Cl₂(20 mL, 1:1) was

added Hay catalyst (2 mL). The mixture was stirred at rt under

exposure to air for 48 h. The solvent was removed by rotary

evaporation. To the residue was added aq HCl (1 M, 20 mL).

The mixture was extracted with a large volume of CHCl₃. The

organic solution was washed with brine and dried over MgSO₄.

Then CHCl₃was removed under vacuum to give the crude

compound, which was further purified by recrystallization from

CHCl₃to give pure 35 (46 mg, 0.065 mmol, 65%) as a white

solid: mp >200 °C dec; IR (KBr) 3075, 3027, 2911, 2198, 1760,

1735, 1618, 1566, 1523, 1399 cm^-1; ¹H NMR (CDCl₃, 500 MHz)

δ 7.78 (t, J = 1.1 Hz, 2H), 7.50 (d, J = 1.1 Hz, 4H); a meaningful

¹³C NMR spectrum was not obtained due to low solubility; MS

(APCI) calcd for C₁₆H₆I₄705.7, found 705.7 [M]^þ.

of compound 34 (120 mg, 0.234 mmol) in THF (8 mL) was

added LDA (0.39 mL, 1.8 M in THF, 0.70 mmol) dropwise at

-78 °C. The reaction was maintained at -78 °C and stirred for

1 h. To the formed red solution was added TMSCl (0.12 mL,

0.94 mmol) dropwise and the mixture was stirred for 1.5 h. To

the light yellow solution was added aq HCl (1 M, 5 mL) at

-78 °C. The reaction was then warmed to rt and extracted with

CH₂Cl₂. The organic phase was washed with brine, dried over

MgSO₄, concentrated under vacuum, and purified by silica flash

column chromatography (hexanes/CH₂Cl₂, 1:9) to give com-

pound 39 (80 mg, 0.19 mmol, 81%) as a colorless oil: ¹H NMR

(CDCl₃, 500 MHz) δ 8.02 (t, J = 1.3 Hz, 1H), 7.79 (d, J = 1.1

Hz, 2H), 0.27 (s, 9H); GC-MS (EI) calcd for C₁₁H₁₂ISi 426,

found 426 (40%) [M]^þ, 411 (100%) [M - CH₃]^þ. The char-

acterizations are consistent with the literature data.⁷⁵

1,4-Bis(3,5-bis((2,5-bis(decyloxy)-4-((triisopropylsilyl)ethynyl)-

phenyl)ethynyl)phenyl)buta-1,3-diyne (37). Compound 35 (44 mg,

0.063 mmol), compound 36 (150 mg, 0.252 mmol), PdCl₂(PPh₃)₂

(8.9 mg, 0.013 mmol), and CuI (4.8 mg, 0.0063 mmol) were added

to Et₃N (10 mL). The solution was bubbled with N₂at rt for 5 min

and then stirred at rt under N₂protection for 12 h. After the

reaction was complete as checked by TLC analysis, the solvent

was removed by rotary evaporation. To the residue obtained was

added CHCl₃. The mixture was filtered through a MgSO₄pad

and then was sequentially washed with aq HCl (10%) and brine.

The organic layer was dried over MgSO₄, concentrated under

vacuum, and purified by silica flash column chromatography

(hexanes/CH₂Cl₂, 8:2) to yield compound 37 (123 mg, 0.0478

mmol, 76%) as a yellow solid: mp 87-88 °C; IR (KBr) 2924,

(4,4⁰-(5-((Trimethylsilyl)ethynyl)-1,3-phenylene)bis(ethyne-2,1-

diyl)bis(2,5-bis(decyloxy)-4,1-phenylene))bis(ethyne-2,1-diyl)bis-

(triisopropylsilane) (40). Compound 39 (54 mg, 0.13 mmol),

compound 36 (150 mg, 0.252 mmol), PdCl₂(PPh₃)₂(9 mg, 0.01

mmol), and CuI (8 mg, 0.03 mmol) were added to Et₃N (5 mL).

The solution was bubbled with N₂at rt for 5 min and then stirred

at rt under N₂protection for 12 h. After the reaction was

complete as checked by TLC analysis, the solvent was removed

by rotary evaporation. To the residue obtained was added

CHCl₃. The mixture was filtered through a MgSO₄pad and

then was sequentially washed with aq HCl (10%) and brine. The

organic layer was dried over MgSO₄and concentrated under

vacuum. The crude product was purified by silica flash column

chromatography (hexanes/CH₂Cl₂, 85:15) to yield compound

40 (158 mg, 0.116 mmol, 89%) as a yellow wax: IR (KBr) 2925,

1

2859, 2211, 2150, 1633, 1578, 1501, 1467, 1421, 1386 cm^-1; H

2862, 2152, 1579, 1500, 1467, 1422, 1386 cm^-1

;

¹H NMR

(CDCl₃, 500 MHz) δ 7.61 (s, 1H), 7.57 (d, J = 1.5 Hz, 2H),

(73) Li, F.; Yang, S. I.; Ciringh, Y.; Seth, J.; Martin, C. H. III; Singh, D.

L.; Kim, D.; Birge, R. R.; Bocian, D. F.; Holten, D.; Lindsey, J. S. J. Am.

Chem. Soc. 1998, 120, 10001–10017.

€

(75) Mongin, O.; Papamicael, C.; Hoyler, N.; Gossauer, A. J. Org. Chem.

1998, 63, 5568–5580.

(74) Bharathi, P.; Moore, J. S. J. Am. Chem. Soc. 1997, 119, 3391–3392.

1514 J. Org. Chem. Vol. 75, No. 5, 2010

Zhou and Zhao

JOCArticle

6.95 (s, 2H), 6.93 (s, 2H), 4.02 (t, J = 6.7 Hz, 4H), 3.96 (t, J =

6.2 Hz, 4H), 1.87-1.76 (m, 8H), 1.57-1.46 (m, 8H), 1.42-1.22

(m, 48 H), 1.16 (s, 42H), 0.89 (t, J = 7.0 Hz, 6H), 0.86 (t, J =

7.3 Hz, 6H), 0.26 (s, 9H); ¹³C NMR (CDCl₃, 125 MHz) δ 154.8,

154.0, 134.7, 134.4, 124.6, 124.3, 118.3, 116.9, 114.9, 114.0,

103.8, 103.4, 97.1, 95.9, 93.8, 87.6, 70.3, 69.7, 32.3, 30.1, 30.0,

29.94, 29.91, 29.81, 29.80, 29.77, 29.6, 26.6, 26.5, 23.1, 19.1, 19.0,

14.5, 11.8, 0.3; HRMS (MALDI-TOF) calcd for C₈₉H₁₄₂O₄Si₃

1359.0216, found 1359.2765 [M]^þ.

(t, J = 6.6 Hz, 4H), 2.50 (s, 1H), 1.87-1.77 (m, 8H), 1.57-1.46

(m, 8H), 1.42-1.23 (m, 48H), 1.16 (s, 42H), 0.90 (t, J = 7.1 Hz,

6H), 0.86 (t, J = 7.1 Hz, 6H, CH₃); ¹³C NMR (CDCl₃, 125 MHz)

δ 154.5, 153.8, 135.2, 135.1, 124.8, 122.0, 117.9, 116.6, 114.9,

113.5, 103.1, 97.0, 92.7, 88.0, 74.6, 73.8, 72.0, 70.0, 69.5, 68.2, 32.1,

29.92, 29.86, 29.82, 29.73, 29.69, 29.62, 29.59, 29.56, 26.40, 26.38,

22.9, 18.9, 14.3, 11.6; HRMS (MALDI-TOF) calcd for

C₈₈H₁₃₃O₄Si₂1309.9742, found 1311.6287 [M þ H]^þ.

1,8-Bis(3,5-bis((2,5-bis(decyloxy)-4-((triisopropylsilyl)ethynyl)-

phenyl)ethynyl)phenyl)octa-1,3,5,7-tetrayne (44). To a round-

bottom flask containing acetone (8 mL) were added compound

43 (110 mg, 0.0838 mmol) and Hay catalyst (5 mL). The mixture

was stirred at rt under exposure to air for 20 h. When TLC

analysis showed no starting material present, acetone was eva-

porated in vacuo. To the residue was added CHCl₃, and the

resulting content was washed with aq HCl (1 M), satd NaHCO₃,

and brine sequentially. The organic layer was dried over MgSO₄,

concentrated under vacuum, and purified by silica flash column

chromatography (hexanes/CH₂Cl₂, 85:15) to yield compound 44

(94 mg, 0.036 mmol, 86%) as a pale yellow solid: mp 89-90 °C;

IR (KBr) 2924, 2856, 2208, 2150, 1577, 1500, 1467, 1421, 1408,

1387 cm^-1; ¹H NMR (CDCl₃, 500 MHz) δ 7.68 (s, 2H), 7.61 (d,

J = 1.5 Hz, 4H), 6.95 (s, 4H), 6.93 (s, 4H), 4.02 (t, hJ = 6.7 Hz,

8H), 3.97 (t, J = 6.7 Hz, 8H), 1.88-1.78 (m, 16H), 1.59-1.47 (m,

16H), 1.44-1.26 (m, 96H), 1.16 (s, 84H), 0.90 (t, J = 7.0 Hz,

12H), 0.88 (t, J = 7.0 Hz, 12H); ¹³C NMR (CDCl₃, 125 MHz) δ

154.5, 153.9, 135.6, 135.4, 124.9, 121.5, 117.9, 116.6, 114.9, 113.4,

103.1, 97.1, 92.6, 88.2, 76.3, 75.4, 70.0, 69.5, 67.8, 63.8, 32.2, 32.1,

30.0, 29.9, 29.74, 29.71, 29.6, 26.4, 22.94, 22.93, 18.9, 18.8, 14.4,

14.3, 11.6; HRMS (MALDI-TOF) calcd for C₁₇₆H₂₆₆O₈Si₄

2619.9485, found 2620.6651 [M þ H]^þ.

(4,4⁰-(5-Ethynyl-1,3-phenylene)bis(ethyne-2,1-diyl)bis(2,5-bis-

(decyloxy)-4,1-phenylene))bis(ethyne-2,1-diyl)bis(triisopropylsilane)

(41). To a solution of compound 40 (158 mg, 0.116 mmol) in

MeOH/THF (20 mL, 1:1) was added K₂CO₃(50 mg, 0.36 mmol).

The mixture was stirred at rt for 2 h, and then the solvent was

removed by rotary evaporation. The residue was diluted in CH₂Cl₂

and sequentially washed with aq HCl (10%) and brine. The organic

layer was dried over MgSO₄, concentrated under vacuum, and

purified by silica flash column chromatography (hexanes/CH₂Cl₂,

9:1) to yield compound 41 (150 mg, 0.116 mmol, 100%) as a yellow

wax: IR (KBr) 3312, 2925, 2862, 2212, 2151, 1603, 1581, 1499, 1467,

1422, 1385 cm^-1; ¹H NMR (CDCl₃, 500 MHz) δ 7.65 (s, 1H), 7.59

(d, J = 1.4 Hz, 2H), 6.95 (s, 2H), 6.94 (s, 2H), 4.02 (t, J = 6.1 Hz,

4H), 3.97 (t, J = 6.0 Hz, 4H), 3.10 (s, 1H), 1.86-1.78 (m, 8H),

1.56-1.48 (m, 8H), 1.42-1.22 (m, 48H), 1.16 (s, 42H), 0.90 (t, J =

6.8Hz, 6H), 0.86(t, J=7.0Hz, 6H);¹³CNMR(CDCl₃, 125MHz)

δ 154.7, 154.0, 134.85, 134.84, 124.7, 123.3, 118.2, 116.9, 115.0,

113.9, 103.4, 97.2, 93.2, 87.8, 82.5, 78.6, 70.2, 69.7, 32.3, 30.12,

30.07, 30.04, 29.96, 29.92, 29.83, 29.80, 29.78, 26.63, 26.60, 23.1,

19.2, 14.5, 11.8; HRMS (MALDI-TOF) calcd for C₈₆H₁₃₄O₄Si₂

1286.9821, found 1286.9424 [M]^þ.

(4,4⁰-(5-((Trimethylsilyl)buta-1,3-diynyl)-1,3-phenylene)bis-

(ethyne-2,1-diyl)bis(2,5-bis(decyloxy)-4,1-phenylene))bis(ethyne-

1,4-Bis(3,5-bis((4-((2,5-bis(decyloxy)-4-((triisopropylsilyl)ethynyl)-

phenyl)ethynyl)-2,5-bis(decyloxy)phenyl)ethynyl)phenyl)buta-1,3-

diyne (46). Compound 35 (30 mg, 0.043 mmol), compound 11

(173 mg, 0.172 mmol), PdCl₂(PPh₃)₂(6.0 mg, 0.0086 mmol), and

CuI (3.3 mg, 0.017 mmol) were added to Et₃N (10 mL). The

solution was bubbled with N₂at rt for 5 min and then stirred at rt

under N₂protection for 12 h. After the reaction was complete as

checked by TLC analysis, the solvent was removed by rotary

evaporation. To the obtained residue was added CHCl₃. The

mixture was filtered through a MgSO₄pad and then was

sequentially washed with aq HCl (10%) and brine. The organic

layer was dried over MgSO₄, concentrated under vacuum, and

purified by silica flash column chromatography (hexanes/

CH₂Cl₂, 7:3) to yield compound 46 (156 mg, 0.0369 mmol,

86%) as a yellow wax: IR (KBr) 2924, 2855, 2213, 2149, 1624,

1579, 1507, 1467, 1425, 1385 cm^-1; ¹H NMR (CDCl₃, 500 MHz)

δ 7.68 (s, 2H), 7.63 (d, J = 6.4 Hz, 4H), 7.02 (s, 4H), 7.00 (s, 4H),

6.96 (s, 4H), 6.94 (s, 4H), 4.07-4.02 (m, 24H), 3.97 (t, J = 6.4 Hz,

8H), 1.88-1.77 (m, 32H), 1.59-1.46 (m, 32H), 1.39-1.25 (m,

192H), 1.15 (s, 84H), 0.91-0.84(m, 48H); ¹³C NMR (CDCl₃, 125

MHz) δ 154.8, 154.2, 153.9, 153.7, 135.3, 135.1, 125.0, 122.8,

118.3, 117.6, 117.4, 116.9, 115.3, 114.7, 114.5, 113.6, 103.4, 97.0,

93.2, 92.3, 91.6, 88.1, 80.7, 75.1, 70.3, 70.2, 70.0, 69.6, 32.4, 30.2,

30.12, 30.08, 29.99, 29.91, 29.81, 29.76, 26.7, 26.6, 26.4, 23.2, 19.2,

14.6, 11.8; HRMS (MALDI-TOF) calcd for C₂₈₃H₄₄₀O₁₆Si₄

4221.2850, found 4221.5151 [M]^þ.

1,4-Bis(3,5-bis((4-((2,5-bis(decyloxy)-4-ethynylphenyl)ethynyl)-

2,5-bis(decyloxy)phenyl)ethynyl)phenyl)buta-1,3-diyne (47). To

a solution of compound 46 (156 mg, 0.0369 mmol) in THF

(6 mL) was added TBAF (0.1 mL, 1 M, 0.1 mmol). The mixture

was stirred at rt for 30 min, and then the solvent was removed by

rotary evaporation. To the residue were added CHCl₃and aq

HCl (1 M). The organic layer was isolated, washed with brine,

and dried over MgSO₄. Filtration to remove MgSO₄followed by

evaporation under vacuum and silica flash column chromato-

graphy (hexanes/CH₂Cl₂, 7:3) afforded compound 47 (133 mg,

0.0369 mmol, 100%) as a brownish solid: mp 61-62 °C; IR

2,1-diyl)bis(triisopropylsilane) (42). To

a flask containing

acetone (8 mL) were added 41 (161 mg, 0.116 mmol), trimethyl-

silylacetylene (0.164 mL, 1.16 mmol), and Hay catalyst (2 mL).

The mixture was stirred at rt under exposure to air for 40 h.

When TLC analysis showed no starting material present, acet-

one was evaporated in vacuo. CHCl₃(30 mL) was added, and

the resulting content was washed with aq HCl (1 M), satd

NaHCO₃, and brine sequentially. The organic layer was dried

over MgSO₄, evaporated under vacuum, and purified by silica

flash column chromatography (hexanes/CH₂Cl₂, 4:1) to yield

compound 42 (143 mg, 0.103 mmol, 89%) as a yellow wax: IR

(KBr) 2925, 2861, 2211, 2151, 2102, 1620, 1579, 1499, 1467,

1421, 1385 cm^-1; ¹H NMR (CDCl₃, 500 MHz) δ 7.65 (s, 1H),

7.56 (d, J = 1.3 Hz, 2H), 6.95 (s, 2H), 6.93 (s, 2H), 4.02 (t, J =

6.4 Hz, 4H), 3.97 (t, J = 6.4 Hz, 4H), 1.87-1.78 (m, 8H),

1.57-1.46 (m, 8H), 1.41-1.25 (m, 48 H), 1.16 (s, 42H), 0.90 (t,

J = 7.0 Hz, 6H), 0.87 (t, J = 7.0 Hz, 6H), 0.25 (s, 9H); ¹³C NMR

(CDCl₃, 125 MHz) δ 154.7, 154.0, 135.3, 135.2, 124.9, 122.6, 118.2,

116.9, 115.0, 113.8, 103.3, 97.2, 93.0, 91.8, 88.1, 88.0, 75.5, 75.4,

70.2, 69.7, 32.3, 30.12, 30.07, 30.00, 29.94, 29.87, 29.80, 29.76, 26.61,

26.57, 23.1, 19.1, 19.0, 14.5, 11.8, 0.0; HRMS (MALDI-TOF) calcd

for C₉₁H₁₄₂O₄Si₃1383.0216, found 1384.0779 [M þ H]^þ.

(4,4⁰-(5-(Buta-1,3-diynyl)-1,3-phenylene)bis(ethyne-2,1-diyl)-

bis(2,5-bis(decyloxy)-4,1-phenylene))bis(ethyne-2,1-diyl)bis-

(triisopropylsilane) (43). To a solution of compound 42 (143 mg,

0.103 mmol) in MeOH/THF (8 mL, 1:1) was added K₂CO₃

(50 mg, 0.36 mmol). The mixture was stirred at rt for 2 h, and

then the solvent was removed by rotary evaporation. The residue

was diluted in CH₂Cl₂and sequentially washed with aq HCl

(10%) and brine. The organic layer was dried over MgSO₄,

concentrated under vacuum, and purified by silica flash column

chromatography (hexanes/CH₂Cl₂, 85:15) to yield compound 43

(110 mg, 0.0838 mmol, 81%) as a yellow wax: IR (KBr) 3312,

2925, 2861, 2214, 2151, 1617, 1578, 1499, 1467, 1422, 1385 cm^-1

;

¹H NMR (CDCl₃, 500 MHz) δ 7.67 (s, 1H), 7.60 (d, J = 1.4 Hz,

2H), 6.95 (s, 2H), 6.93 (s, 2H), 4.02 (t, J = 6.6 Hz, 4H), 3.97

J. Org. Chem. Vol. 75, No. 5, 2010 1515

Zhou and Zhao

JOCArticle

(KBr) 3315, 3296, 2924, 2853, 2209, 2105, 1602, 1577, 1506, 1468,

1624, 1579, 1557, 1539, 1507, 1467, 1427, 1386 cm^-1; ¹H NMR

(CDCl₃, 500 MHz) δ 7.66 (s, 1H), 7.58 (d, J = 1.4 Hz, 2H), 7.03

(s, 2H), 7.00 (s, 2H), 6.96 (s, 2H), 6.95 (s, 2H), 4.06-4.02 (m,

12H), 3.96 (t, J = 6.0 Hz, 4H), 1.88-1.80 (m, 16H), 1.55-1.50

(m, 16H), 1.41-1.26 (m, 96H), 1.16 (s, 42H), 0.92-0.86 (m,

24H), 0.26 (s, 9H); ¹³C NMR (CDCl₃, 125 MHz) δ 154.8, 154.3,

153.9, 153.7, 135.24, 135.19, 124.9, 122.7, 118.4, 117.6, 117.5,

116.9, 115.4, 114.8, 114.6, 113.7, 103.5, 96.9, 93.2, 92.3, 91.8,

91.6, 88.1, 88.0, 75.5, 75.4, 70.3, 70.2, 70.0, 69.7, 32.3, 30.13,

30.07, 29.98, 29.9, 29.8, 26.7, 26.6, 26.4, 23.1, 19.1, 14.5, 11.8,

0.0; HRMS (MALDI-TOF) calcd for C₁₄₇H₂₃₀O₈Si₃2207.6899,

found 2207.8487 [M]^þ.

Compound 51. To a solution of compound 50 (230 mg, 0.104

mmol) in MeOH/THF (20 mL, 1:1) was added K₂CO₃(50 mg,

0.36 mmol). The mixture was stirred at rt for 1 h, and then the

solvent was removed by rotary evaporation. The residue was

diluted in CHCl₃and then sequentially washed with aq HCl

(10%) and brine. The organic layer was dried over MgSO₄,

concentrated under vacuum, and purified by silica flash column

chromatography (hexanes/CH₂Cl₂, 7:3) to yield compound 51

(201 mg, 0.094 mmol, 91%) as a yellow solid: mp 57-58 °C; IR

(KBr) 3314, 2924, 2855, 2212, 2149, 1670, 1636, 1578, 1560, 1542,

1508, 1468, 1426, 1386 cm^-1; ¹H NMR (CDCl₃, 500 MHz) δ 7.71

(s, 1H), 7.63 (d, J = 1.5 Hz, 2H), 7.06 (s, 2H), 7.03 (s, 2H), 6.99

(s, 2H), 6.98 (s, 2H), 4.08-4.02 (m, 12H), 3.98 (t, J = 6.7 Hz, 4H),

2.50 (s, 1H), 1.90-1.80 (m, 16H), 1.58-1.50 (m, 16H), 1.42-1.25

(m, 96H), 1.19 (s, 42H), 0.92-0.87 (m, 24H); ¹³C NMR (CDCl₃,

125 MHz) δ 154.8, 154.3, 153.9, 153.7, 135.4, 135.3, 125.0, 122.3,

118.4, 117.6, 117.5, 116.9, 115.5, 114.8, 114.6, 113.6, 103.5, 96.9,

93.1, 92.3, 91.6, 88.2, 74.8, 74.0, 72.3, 70.3, 70.2, 70.0, 69.7, 68.3,

32.4, 30.16, 30.12, 30.08, 30.05, 29.98, 29.95, 29.92, 29.8, 26.67,

26.63, 26.4, 23.1, 19.2, 14.5, 11.8; HRMS (MALDI-TOF) calcd

for C₁₄₄H₂₂₂O₈Si₂2135.6503, found 2135.6761 [M]^þ.

Compound 52. To a flask containing acetone/CH₂Cl₂(10 mL,

1:1) were added compound 51 (200 mg, 0.0940 mmol) and Hay

catalyst (5 mL). The mixture was stirred at rt under exposure to

air for 2 h. When TLC analysis showed no starting material

present, acetone was evaporated in vacuo. CHCl₃(30 mL) was

added. The resulting content was washed with aq HCl (1 M),

satd NaHCO₃, and brine sequentially. The organic layer was

dried over MgSO₄, concentrated under vacuum, and purified by

silica flash column chromatography (hexanes/CH₂Cl₂, 7:3) to

yield compound 52 (166 mg, 0.0389 mmol, 83%) as a yellow

wax: IR (KBr) 2923, 2854, 2207, 2149, 1578, 1507, 1467, 1426,

1388 cm^-1; ¹H NMR (CDCl₃, 500 MHz) δ 7.69 (s,2H), 7.62 (d,

J = 1.5 Hz, 4H), 7.02 (s, 4H), 6.99 (s, 4H), 6.96 (s, 4H), 6.95 (s,

4H), 4.06-4.01 (m, 24H), 3.96 (t, J = 6.7 Hz, 8H), 1.88-1.76

(m, 32H), 1.55-1.48 (m, 32H), 1.37-1.25 (m, 192H), 1.16 (s,

84H), 0.90-0.85 (m, 48H); ¹³C NMR (CDCl₃, 125 MHz) δ

154.8, 154.3, 153.9, 153.7, 135.6, 125.2, 121.7, 118.4, 117.6,

117.5, 117.0, 115.5, 114.7, 114.6, 113.5, 103.5, 97.0, 93.0, 92.3,

91.6, 88.4, 75.6, 70.3, 70.2, 70.0, 69.7, 68.0, 64.0, 32.3, 30.2,

30.11, 30.06, 29.9, 29.8,29.7, 26.6, 26.4, 23.1, 19.1, 14.6, 14.5,

1

1426, 1387 cm^-1; H NMR (CDCl₃, 500 MHz) δ 7.68 (s, 2H),

7.63 (s, 4H), 7.02 (s, 4H), 7.003 (s, 4H), 6.998 (s, 4H), 6.98 (s, 4H),

4.06-3.99 (m, 32H), 3.35 (s, 4H), 1.88-1.79 (m, 32H), 1.58-1.41

(m, 32H), 1.38-1.23 (m, 192 H), 0.90-0.83 (m, 48H); ¹³C NMR

(CDCl₃, 125 MHz) δ 154.4, 154.1, 153.7, 153.6, 135.1, 134.9,

124.8, 122.6, 118.3, 117.5, 117.34, 117.27, 115.14, 115.06, 113.6,

112.9, 93.0, 91.7, 91.6, 87.9,82.5, 80.6, 80.3, 74.9, 70.0, 69.8, 32.1,

30.0, 29.90, 29.85, 29.81, 29.80, 29.7, 29.59, 29.56, 29.4, 26.4,

26.2, 22.9, 14.3; HRMS (MALDI-TOF) calcd for C₂₄₈H₃₆₂O₁₆

3596.7513, found 3597.7497 [M þ H]^þ.

Compound 48. Compound 39 (70 mg, 0.16 mmol), compound

11 (329 mg, 0.326 mmol), PdCl₂(PPh₃)₂(11.4 mg, 0.0163 mmol),

and CuI (6.2 mg, 0.033 mmol) were added to Et₃N (6 mL). The

solution was bubbled with N₂at rt for 5 min and then stirred at rt

for 8 h. After the reaction was complete as checked by TLC

analysis, the solvent was removed by rotary evaporation. The

residue was diluted in CHCl₃, and the mixture was filtered

through a MgSO₄pad. The solution obtained was sequentially

washed with aq HCl (10%) and brine. The organic layer was

dried over MgSO₄, concentrated under vacuum, and purified by

silica flash column chromatography (hexanes/CH₂Cl₂, 4:1) to

yield compound 48 (330 mg, 0.151 mmol, 94%) as a yellow solid:

mp 42-43 °C; IR (KBr) 2925, 2855, 2210, 2148, 1624, 1579,

1

1508, 1469, 1426, 1386 cm^-1; H NMR (CDCl₃, 500 MHz) δ

7.62 (s, 1H), 7.58 (d, J = 1.6, 2H), 7.02 (s, 2H), 6.99 (s, 2H), 6.96

(s, 2H), 6.95 (s, 2H), 4.04-4.01 (m, 12H), 3.96 (t, J = 6.5 Hz, 4H),

1.87-1.76 (m, 16H), 1.53-1.48 (m, 16H), 1.37-1.24 (m, 96 H),

1.16 (s, 42H), 0.90-0.83 (m, 24H), 0.27 (s, 9H); ¹³C NMR

(CDCl₃, 125 MHz) δ 154.5, 153.9, 153.6, 153.5, 134.6, 134.2,

124.3, 124.0, 118.1, 117.4, 117.3, 116.7, 114.9, 114.5, 114.2, 113.6,

103.6, 103.2, 96.7, 95.7, 93.3, 92.0, 91.4, 87.4, 70.0, 69.9, 69.8, 69.4,

32.1, 29.90, 29.86, 29.76, 29.7, 29.69, 29.6, 29.59, 29.4, 26.4, 26.3,

26.2, 22.9, 18.9, 14.3, 11.6, 0.1; HRMS (MALDI-TOF) calcd for

C

₁₄₅H₂₃₀O₈Si₃2183.6899, found 2183.0253 [M]^þ.

Compound 49. To a solution of compound 48 (336 mg, 0.154

mmol) in MeOH/THF (6 mL, 1:1) was added K₂CO₃(50 mg,

0.36 mmol). The mixture was stirred at rt for 2 h, and then the

solvent was removed by rotary evaporation. The residue was

diluted in CH₂Cl₂and sequentially washed with aq HCl (10%)

and brine. The organic layer was dried over MgSO₄, concen-

trated under vacuum, and purified by silica flash column

chromatography (hexanes/CH₂Cl₂, 7:3) to yield compound 49

(268 mg, 0.127 mmol, 83%) as a yellow solid: mp 65-66 °C; IR

(KBr) 3262, 2955, 2924, 2855, 2209, 2149, 1670, 1626, 1580,

1

1508, 1467, 1426, 1385 cm^-1; H NMR (CDCl₃, 500 MHz) δ

7.66 (s, 1H), 7.60 (d, J = 0.9 Hz, 2H), 7.03 (s, 2H), 7.00 (s, 2H),

6.96 (s, 2H), 6.95 (s, 2H), 4.06-4.02 (m, 12H), 3.96 (t, J = 6.6

Hz, 4H), 3.11 (s, 1H), 1.89-1.77 (m, 16H), 1.57-1.48 (m, 16H),

1.42-1.26 (m, 96H), 1.16 (s, 42H), 0.92-0.85 (m, 24H); ¹³C

NMR (CDCl₃, 125 MHz) δ 154.8, 154.2, 153.9, 153.7, 134.9,

134.8, 124.7, 123.2, 118.3, 117.5, 117.4, 116.9, 115.2, 114.7,

114.5, 113.7, 103.4, 96.9, 93.4, 92.2, 91.6, 87.8, 82.5, 78.6, 70.2,

70.1, 70.0, 69.6, 32.3, 30.14, 30.08, 29.9, 29.8, 29.7, 26.7, 26.6,

26.4, 23.1, 19.2, 14.5, 11.8; HRMS (MALDI-TOF) calcd for

11.8; HRMS (MALDI-TOF) calcd for

C₂₈₈H₄₄₂O₁₆Si₄

4269.2850, found 4269.2584 [M]^þ.

C

₁₄₂H₂₂₂O₈Si₂2111.6503, found 2112.6151 [M þ H]^þ.

Compound 50. To a flask containing acetone (10 mL) were

Acknowledgment. We thank NSERC, CFI, and IRIF for

financial support. N.Z. recevided an NSERC-PGS D scho-

larship during the period of this research. Prof. E. Merschrod

of Memorial University is acknowledged for her initial

contribution to the AFM characterization on compound 3a.

added compound 49 (268 mg, 0.127 mmol), trimethylsilylacety-

lene (0.179 mL, 1.27 mmol), and Hay catalyst (5 mL). The

mixture was stirred at rt under exposure to air for 45 h. When

TLC analysis showed no starting material present, acetone was

evaporated under vacuum, and to the residue was added CHCl₃

(30 mL). The resulting mixture was washed with aq HCl (1 M),

satd NaHCO₃, and brine sequentially. The organic layer was

dried over MgSO₄, concentrated under vacuum, and purified by

silica flash column chromatography (hexanes/CH₂Cl₂, 7:3) to

yield compound 50 (235 mg, 0.106 mmol, 84%) as a yellow solid:

mp 57-58 °C; IR (KBr) 2958, 2924, 2854, 2209, 2150, 2101,

Supporting Information Available: ¹H and ¹³C NMR spec-

troscopic characterization data of all new compounds. DSC

data of compounds 9 and 19. UV-vis absorption and AFM

analyses of compounds 2a, 2b, and 5a. This material is available

free of charge via the Internet at http://pubs.acs.org.

1516 J. Org. Chem. Vol. 75, No. 5, 2010

Article Doi

Conjugated oligoyne-bridged [60]fullerene molecular dumbbells: Syntheses and thermal and morphological properties

DOI: 10.1021/jo9021748

Source and publish data:

Authors:

Article abstract of DOI:10.1021/jo9021748

Full text of DOI:10.1021/jo9021748

Products guided by the article

R&D Labs maybe for 1211509-33-9

Relevant to this article

Hot Product