Synthesis of 2,3,9,10,16,17,23,24-octaalkynylphthalocyanines and the effects of concentration and temperature on their 1H NMR spectra

Article abstract of DOI:10.1021/jo9521662

The syntheses of 3,4- and 4,5-diiodophthalonitriles are described. Coupling of the latter compound with Pd(PPh₃)₂Cl₂ and 1-octyne, 1-heptyne, 1-hexyne, 1-pentyne, and 3,3-dimethyl-1-butyne gave a series of 4,5-dialkynylphthalonitriles. Hydrogenation of 4,5-bis(1-pentynyl)phthalonitrile and 4,5-bis(3,3-dimethyl-1-butynyl)phthalonitrile gave 4,5-dipentylphthalonitrile and 4,5-bis(3,3-dimethylbutyl)phthalonitriles. Condensation of the dialkynylphthalonitriles with lithium 1-pentoxide in 1-pentanol gave 2,3,9,10,16,17,23,24-octaalkynylphthalocyanines, while intervention of the intermediate dilithium phthalocyanines with zinc acetate gave the related zinc(II) phthalocyanines. ¹H NMR spectroscopy of these octaalkynylphthalocyanines exhibited large chemical shifts (1-2 ppm) of the internal and aromatic protons at concentrations ranging from 10^-2 to 10^-5 M and at temperatures from 27 to 147°C. The effects of aggregation phenomena are discussed. The importance of reporting concentration and temperature values for NMR spectra of phthalocyanines is stressed.

Full text of DOI:10.1021/jo9521662

3034
J . Org. Chem. 1996, 61, 3034-3040
Syn th esis of 2,3,9,10,16,17,23,24-Octa a lk yn ylp h th a locya n in es a n d
1
th e Effects of Con cen tr a tion a n d Tem p er a tu r e on Th eir H NMR
Sp ectr a
Dmitri S. Terekhov, Kieran J . M. Nolan, Colin R. McArthur, and Clifford C. Leznoff*
Department of Chemistry, York University, North York, Toronto, Ontario M3J 1P3, Canada
Received December 5, 1995X
The syntheses of 3,4- and 4,5-diiodophthalonitriles are described. Coupling of the latter compound
with Pd(PPh3)2Cl2 and 1-octyne, 1-heptyne, 1-hexyne, 1-pentyne, and 3,3-dimethyl-1-butyne gave
a series of 4,5-dialkynylphthalonitriles. Hydrogenation of 4,5-bis(1-pentynyl)phthalonitrile and
4,5-bis(3,3-dimethyl-1-butynyl)phthalonitrile gave 4,5-dipentylphthalonitrile and 4,5-bis(3,3-di-
methylbutyl)phthalonitriles. Condensation of the dialkynylphthalonitriles with lithium 1-pentoxide
in 1-pentanol gave 2,3,9,10,16,17,23,24-octaalkynylphthalocyanines, while intervention of the
intermediate dilithium phthalocyanines with zinc acetate gave the related zinc(II) phthalocyanines.
1H NMR spectroscopy of these octaalkynylphthalocyanines exhibited large chemical shifts (1-2
ppm) of the internal and aromatic protons at concentrations ranging from 10-2 to 10-5 M and at
temperatures from 27 to 147 °C. The effects of aggregation phenomena are discussed. The
importance of reporting concentration and temperature values for NMR spectra of phthalocyanines
is stressed.
In tr od u ction
ylphthalonitriles14,15 which have been used to synthesize
alkynylphthalocyanines, but 4,5-dialkynylphthalonitriles
have hitherto been rarely accessible for elaboration into
polyalkynylphthalocyanines.16 Since monoiodophthaloni-
triles are key starting materials for monoalkynylphthalo-
nitriles, the preparation of some unknown polyiodo-
phthalonitriles was a prerequisite for preparing poly-
alkynylphthalonitriles.
2,3,9,10,16,17,23,24-Octasubstituted phthalocyanines
and other phthalocyanines have found wide applications1
in a number of areas, outside their traditional uses as
dyes,2 including liquid crystals,3 chemical sensors,1,4
nonlinear optics,5 and electrical and even biological
applications.1,6 The description of hexaalkynylbenzenes7
as possible compounds for use in nonlinear optics has
piqued our interest in related polyalkynylphthalocya-
nines. Although 2,3,9,10,16,17,23,24-octaalkoxyphthalo-
cyanines,8 2,3,9,10,16,17,23,24-octakis(alkoxymethyl)-
phthalocyanines,3,9 and 2,3,9,10,16,17,23,24-octaalkyl-
phthalocyanines10-12 have been known for some time
now, the methods used for their preparation are not
applicable to the syntheses of the alkynylphthalocyanines
described herein. Both 4-iodophthalonitrile13,14 and 3-io-
dophthalonitrile15 have been used to prepare monoalkyn-
Resu lts a n d Discu ssion
Syn th esis. Electrophilic aromatic iodination of aro-
matic compounds containing two electron-withdrawing
groups is quite rare but can be accomplished using iodine
in fuming sulfuric acid at temperatures greater than 60
°C.17,18 Thus, phthalimide (1) was directly iodinated with
iodine in 30% fuming sulfuric acid at 70-75 °C to give
4,5-diiodophthalimide (2), a trace of 3,4-diiodophthalim-
ide (3), and 4,5-diiodophthalic acid (4) from which 2 and
4 were isolated in 75 and 20% yields, respectively. If the
reaction was allowed to proceed at 85-90 °C, a larger
amount of 3 (inseparable from 2) was produced. Pure 2,
on treatment with concentrated ammonia, gave pure 4,5-
diiodophthalamide (5), while similar treatment of a
mixture of 2 and 3 gave a mixture of 5 and 3,4-
diiodophthalamide (6). Treatment of 5 with trifluoro-
acetic anhydride in pyridine,19,20 gave 4,5-diiodophthalo-
nitrile (7) in 79% yield, while similar treatment of the
X Abstract published in Advance ACS Abstracts, April 1, 1996.
(1) Phthalocyanines: Properties and Applications; Leznoff, C. C.,
Lever, A. B. P., Eds.; VCH: New York, 1989, 1992, 1993; Vols. 1-3.
(2) Moser, F. H.; Thomas, A. L. The Phthalocyanines; CRC: Boca
Raton, 1983; Vols. 1, 2.
(3) Piechocki, C.; Simon, J .; Skoulious, A.; Guillon, D.; Weber, P. J .
Am. Chem. Soc. 1982, 104, 5245. Piechocki, C.; Simon, J . Nouv. J .
Chim. 1985, 9, 159.
(4) Snow, A. W.; Barger, W. R.; Klusty, M.; Wohltjen, H.; J arvis, N.
L. Langmuir 1986, 2, 513. Wo¨hrle, D.; Kaneko, M. Yuki Gosei Kagaku
Kyokai Shi 1987, 45, 837.
(5) Grund, A.; Kaltbeitzel, A.; Mathy, A.; Schwarz, R.; Bubeck, C.;
Vernmehren, P.; Hanack, M. J . Phys. Chem. 1992, 96, 7450.
(6) Paquette, B.; van Lier, J . E. In Photodynamic Therapy: Basic
Principles and Clinical Aspects; Henderson, B. W., Dougherty, T. J .,
Eds.; Marcel Dekker: New York, 1992; p 145.
(7) Kondo, K.; Yasuda, S.; Sakaguchi, T.; Miya, M. J . Chem. Soc.,
Chem. Commun. 1995, 55.
(13) Keller, T. M.; Griffith, J . R. U.S. Pat. 4,209,458, 1980; Chem.
Abstr. 1980, 93, 221298a.
(14) Marcuccio, S. M.; Svirskaya, P. I. Greenberg, S.; Lever, A. B.
P.; Leznoff, C. C.; Tomer, K. B. Can. J . Chem. 1985, 63, 3057.
(15) Leznoff, C. C.; Terekhov, D. S.; McArthur, C. R.; Vigh, S.; Li,
J . Can. J . Chem. 1995, 73, 435.
(16) Leznoff, C. C.; McArthur, C. R.; Qin, Y. Can. J . Chem. 1993,
71, 1319.
(17) Arotsky, J .; Butler, R.; Darby, A. C. J . Chem. Soc. C 1970, 1480.
Mattern, D. L. J . Org. Chem. 1984, 49, 3051.
(18) Pratt, D. S.; Perkins, G. A. J . Am. Chem. Soc. 1918, 40, 219.
(19) Campagna, F.; Carotti, A.; Casini, G. Tetrahedron Lett. 1977,
1813.
(8) Masurel, S.; Sirlin, C.; Simon, J . New J . Chem. 1987, 11, 455.
Hanack, M.; Gu¨l, A.; Hirsch, A.; Mandal, B. K; Subramanian, L. R.;
Witke, E. Mol. Cryst. Liq. Cryst. 1990, 187, 365. Ohta, K.; J acquemin,
L.; Sirlin, C.; Bosio, L.; Simon, J . New J . Chem. 1988, 12, 751. Cho, I.,
Lim, Y. Mol. Cryst. Liq. Cryst. 1988, 154, 9. Ford, W. T.; Sumner, L.
Zhu, W.; Chang, Y. H.; Um, P.-J .; Choi, K. H.; Heiney, P. A.;
Maliszewskyj, N. C. New J . Chem. 1994, 18, 495.
(9) Pawlowski, G.; Hanack, M. Synthesis 1980, 287.
(10) Cuellar, E. A.; Marks, T. J . Inorg. Chem. 1981, 20, 3766.
Camenzind, M. J .; Hill, C. L. J . Heterocycl. Chem. 1985, 22, 575.
(11) Hanack, M.; Haisch, P.; Lehmann, H.; Subramanian, L. R.
Synthesis 1993, 387.
(12) Nishi, H.; Azuma, N.; Kitahara, K. J . Heterocycl. Chem. 1992,
29, 475. Nishi, H.; Ueno, S. Nippon Kagaku Kaishi 1989, 983.
(20) Hall, T. W.; Greenberg, S.; McArthur, C. R. Khouw, B.; Leznoff,
C. C. Nouv. J . Chem. 1982, 6, 653. Drew, D. M. Ph.D. Thesis, York
University, 1995.
S0022-3263(95)02166-9 CCC: $12.00 © 1996 American Chemical Society

Synthesis of Octaalkynylphthalocyanines
J . Org. Chem., Vol. 61, No. 9, 1996 3035
Sch em e 1
O
O
R
I
I
CO2H
NH4OH
I2
NH
+
NH
c-H2SO4
I
CO2H
O
O
R′
1
2, R = I, R′ = H
3, R = H, R′ = I
4
I
I
CO2NH2
CO2NH2
CO2NH2
I
I
CN
CN
CN
CN
(CF3CO)2O
py
+
+
I
CO2NH2
I
I
I
5
6
7
8
Sch em e 2
mixture of 5 and 6 gave 7 and 3,4-diiodophthalonitrile
(8) isolated in 80% and 10% yields, respectively (Scheme
1).
dialkynylphthalonitriles 14-18 in 70-90% yields. Com-
pounds 14-18 were readily soluble in most organic
solvents and were converted using lithium 1-pentoxide
Coupling of an excess of the terminal alkynes 9-12
with 4,5-diiodophthalonitrile (7) in triethylamine (TEA)
at 110 °C using Pd(PPh3)2Cl2 as a catalyst21 or 3,3-
dimethyl-1-butyne (13) in TEA at room temperature
using Pd(PPh3)2Cl2 and CuI as catalysts22,23 gave the 4,5-
(21) Dieck, H. A.; Heck, F. R. J . Organomet. Chem. 1975, 93, 259.
(22) Sonogashira, K.; Tohda, Y., Hagihara, N. Tetrahedron Lett.
1975, 4467.
(23) Nguyen, B. V.; Yang, Z. Y.; Burton, D. J . J . Org. Chem. 1993,
58, 7368.

3036 J . Org. Chem., Vol. 61, No. 9, 1996
Terekhov et al.
Sch em e 3
Sch em e 4
in 1-pentanol24,25 at 110 °C into their respective metal-
free 2,3,9,10,16,17,23,24-octaalkynylphthalocyanines 19-
23. Attempts at converting the metal-free Pcs 19-23
into zinc Pcs using Zn(OAc)2 in N,N-dimethylformamide
(DMF) at 120 °C was unsuccessful in that incomplete
metalation and some bleaching of the pigment occurred.
Consequently, the dilithium Pcs, prepared as nonisolated
intermediates in the preparation of 19-23, were treated
in situ with Zn(OAc)2 at 60 °C to provide the fully metaled
zinc(II) 2,3,9,10,16,17,23,24-octaalkynylphthalocyanines
24-28 in 35-45% yields, respectively (Scheme 2). Al-
though the zinc(II) Pcs 24-28 were somewhat less
soluble in organic solvents than the metal-free Pcs 19-
23, they were still quite soluble in most organic solvents.
The relative mobilities of the zinc(II) Pcs on thin-layer
chromatography using CHCl3 as eluent are 28 > 24 >
25 > 26 > 27, as expected with the bulky tert-butyl
groups of 28, reducing aggregation and increasing its
mobility.
It is important to note that although 19-23 and 24-
28 exhibit Q-bands typical of metal-free and metalated
Pcs, respectively, the λmax values of the most red-shifted
band is red-shifted by approximately 1 eV per alkynyl
group compared to unsubstituted phthalocyanines so that
the λmax of 23, for example, is 732 nm and that of 28 is
712 nm.
When 7 was coupled as before but in triethylamine
(TEA) and with only 2 equiv of 1-octyne (9), a mixture of
14 and the monocoupled product 4-iodo-5-(1-octynyl)-
phthalonitrile (29) were produced in 40 and 30% yields,
respectively (Scheme 3). Although the identity of 4,5-
diiodophthalonitrile (7) is firmly based on NMR chemical
shift data, the isolation of 29 exhibiting two different
singlets in its NMR spectrum clearly corroborates that 7
could not be 3,6-diiodophthalonitrile, whose monocoupled
product would yield two different doublets.
F igu r e 1. Chemical shift of internal protons of metal-free
phthalocyanines as a function of log concentration (mol/L). 1H
NMR in C6D6 at 27 °C: 2, (3,3-dimethylbutynyl)8PcH2 (23);
b, (hexynyl)8PcH2 (21); 9, (heptynyl)8PcH2 (20). 1H NMR in
CDCl3 at 27 °C; 1, (3,3-dimethylbutynyl)8PcH2 (23).
followed by hydrogenation is a desirable alternative to
other multistep preparations of 4,5-dialkylphthalo-
nitriles10-12 which require low-yield reactions using
CuCN.
Con cen tr a tion a n d Tem p er a tu r e Effects in 1H
NMR Sp ectr oscop y of th e P h th a locya n in es. Some
earlier work on the effect of concentration on tetrasub-
stituted phthalocyanines14 was limited due to the facts
that mixtures of tetrasubstituted isomers were always
present and lower field instrumentation did not allow the
collection of data on very dilute solutions. The octaalkyn-
ylphthalocyanines described herein are all single isomers,
and both internal and aromatic protons give simple
singlets. Initial 1H NMR spectra obtained for Pcs at 10-2
M in benzene-d6 showed that the internal protons of the
tert-butylethynyl Pc 23 were further downfield than the
internal protons of the other four Pcs 19-22 at the same
concentration. This observation can be readily explained
by the fact that the bulky tert-butylethynyl groups
prevent aggregation far better than the linear alkynyl
groups. These results bring up an interesting point.
What is the actual absorption value of the internal and
aromatic protons of an unaggregated Pc in a specific
solvent?
It was decided that a series of concentration and
temperature 1H NMR studies would be carried out on
the Pcs described in Scheme 2. The results of these
experiments are depicted in Figures 1-5. The effect of
Catalytic hydrogenation of 4,5-bis(1-pentynyl)phthalo-
nitrile (17) or 4,5-bis(3,3-dimethyl-1-butynyl)phthaloni-
trile (18) with hydrogen over a Pd/C catalyst gave 4,5-
dipentylphthalonitrile (30) and 4,5-bis(3,3-dimethyl-
butyl)phthalonitrile (31) in yields greater than 95%
(Scheme 4).
1
concentration on the H NMR chemical shifts of the Pcs
was studied over the concentration range of 10-2-10-5
M in benzene-d6. It is apparent that for the internal NH
protons the chemical shifts changes by almost 2 ppm
downfield as the concentration approaches 10-5 M (Fig-
ure 1). At this latter concentration the Pc solution is
almost colorless, and 20 000 scans were required to
obtain satisfactory spectra. The chemical shift changes
with concentration are readily explained by the high
aggregation26,27 of phthalocyanines and the fact that the
cone of aromaticity of one Pc ring generally causes upfield
It should be noted that the preparation of 4,5-dialkyl-
phthalonitriles 30 and 31 via 7 and a terminal alkyne
(24) Linstead, R. P.; Lowe, A. R. J . Chem. Soc. 1934, 10220. Barrett,
P. A.; Frye, D. A.; Linstead, R. P. J . Chem. Soc. 1938, 1157.
(25) J in, Z.; Nolan, K.; McArthur, C. R.; Lever, A. B. P.; Leznoff, C.
C. J . Organomet. Chem. 1994, 468, 205.

Synthesis of Octaalkynylphthalocyanines
J . Org. Chem., Vol. 61, No. 9, 1996 3037
F igu r e 2. Chemical shift of aromatic protons of metal free
phthalocyanines, as a function of log concentration (mol/L).
1H NMR in C6D6 at 27 °C: 9, (3,3-dimethylbutynyl)8PcH2 (23);
b, (hexynyl)8PcH2 (21); 2, (heptynyl)8PcH2 (20). 1H NMR in
F igu r e 3. Chemical shift of aromatic protons of zinc phthalo-
cyanines, as a function of log concentration (mol/L). H NMR
in C6D6 at 27 °C: 2, (3,3-dimethylbutynyl)8PcZn (28); b,
(hexynyl)8PcZn (26); 9, (octynyl)8PcZn (24).
1
1
CDCl3 at 27 °C; 1, (3,3-dimethylbutynyl)8PcH2 (23). H NMR
in nitrobenzene-d5 at 27 °C: 9, (3,3-dimethylbutynyl)8PcH2
(23).
shifts of its aggregated partners. It is likely that the
aggregated dimers and oligomers are not static in solu-
tion and can slide over each other and rotate.28 The
maximum concentration of the Pcs was limited by their
solubility, while the lowest concentration was limited by
the acquisition times on the NMR instrument available.
The 1H chemical shifts of the internal and aromatic
protons at high concentrations were broad likely due to
the formation of polymeric aggregates. When a solution
of a Pc becomes more and more diluted, the signals
become sharp, which would be typical for 1H NMR
spectra of monomeric species. At about 10-3 M Pc we
often were able to discern two peaks for internal protons
where the second peak had an intensity about 10% that
of the major peak. This peak actually disappeared at
both lower and higher concentrations and may be due to
discrete “dimer” aggregates.
As expected, the internal protons of 19-23 are more
sensitive to changes in concentration than aromatic
protons (Figure 2) as they are closer to the cone of
aromaticity in aggregated species.
F igu r e 4. Dependence on temperature of the chemical shift
of aromatic protons of metal-free (3,3-dimethylbutynyl)8PcH2
(23): b, in nitrobenzene-d5 (1.1 × 10-3 M); 9, in CDCl3 (3.6 ×
10-3). In C6D6: [, 1.5 × 10-3; 1, 4.0 × 10-4; 2, 9.4 × 10-5
mol/L.
We also wished to study the effects of concentration
1
on the H NMR chemical shifts of the zinc(II) octaalkyn-
ylphthalocyanines 24-28. For these Pcs we observe that
there is still a strong concentration dependence for the
1
linear alkynyl Pcs 24-27 but that the H NMR chemical
ppm in benzene-d6. A similar concentration study of the
1H NMR chemical shifts of the aromatic protons of 23 in
nitrobenzene-d5 exhibited a limiting value at 9.73 ppm.
We wished to examine the effect of temperature on the
1H NMR chemical shifts of the Pcs, but to examine a
suitably wide temperature range we used nitrobenzene-
d5 as the solvent. Using a 10-3 M concentration of 23, it
was shown that the 1H NMR chemical shift of the
aromatic protons of 23 moved downfield from 9.30 ppm
at 27 °C to 9.53 ppm at 137 °C at which point no further
downfield shifts occurred even at higher temperatures
shift of the aromatic protons of the tert-butylethynyl Pc
28 is only slightly concentration dependent (Figure 3).
When a 10 times excess of pyridine-d5 or pyrazine was
added to concentrated solutions of Pcs the 1H NMR
chemical shifts of the aromatic protons of 24-27 ap-
proached the value of the unaggregated Pc at 9.92-9.94
(26) Sigel, H.; Waldmeirer, P.; Prijs, B. J . Inorg. Nucl. Chem. Lett.
1971, 7, 161. Bernauer, K.; Fallab, S. Helv. Chim. Acta 1961, 54, 1287.
Monahan, A. R.; Brado, J . A.; DeLuca, A. F. J . Phys. Chem. 1972, 76,
1994. Abkowitz, M. Monahan, A. R. J . Chem. Phys. 1973, 58, 2281.
(27) Dodsworth, E. S.; Lever, A. B. P.; Seymour, P.; Leznoff, C. C.
J . Phys. Chem. 1985, 89, 5698.
1
(Figure 4). Similarly, the H NMR chemical shifts of the
internal protons shifted from -1.35 ppm to +0.30 ppm
at 157 °C at which point further downfield shifts are less
(28) Hunter, C. A.; Sanders, J . K. M. J . Am. Chem. Soc. 1990, 112,
5525.

3038 J . Org. Chem., Vol. 61, No. 9, 1996
Terekhov et al.
and 100 mL of water was added. This solution was concen-
trated to 500 mL and cooled to give 20 g of a bright-yellow
precipitate of 4,5-diiodophthalimide (2). The mother liquors
were reduced in volume to 100 mL and cooled to give 15 g of
a 4:1 mixture of 2 and 4. Chromatography on silica gel of this
mixture using CHCl3-EtAc (4:1) as eluent gave 2 and 4 in
isolated yields of 75 and 20% respectively.
Compound 2: mp 297-299 °C; IR (KBr) 3150 (NH), 1750
(CdO), 1700 (CdO) cm-1; 1H NMR (400 MHz, DMSO-d6) δ 8.25
(s, 2H), 11.41 (s, 1H); MS m/z (rel intensity) 399 M+, 82). Anal.
Calcd for C8H3I2NO2: C, 24.09; H, 0.76; N, 3.51. Found: C,
24.07; H, 0.66; N, 3.32.
4,5-Diiod op h th a m id e (5). To 220 mL of concd aqueous
ammonia was added 20 g (50 mmol) of pure 4,5-diiodophthal-
imide (2). The rapidly stirred mixture was heated to 50-60
°C for 1.5 h. The white solid was filtered and washed three
times with ice-cold water and with methanol to remove any
trace amounts of ammonia and 2. The solid was dried
overnight at room temperature to give intermediate 5 (17.0 g,
81%) as a white powder: mp 297-299 °C; IR (KBr) [3390,
3280, 3130(NH)], [1680, 1640, (CdO)], 1590 cm-1
;
1H NMR
(DMSO-d6, 27 °C) δ 7.91 (s, 2H), 7.80, 7.39 (bs, 4H).
4,5-Diiod op h th a lon itr ile (7). To an ice-cooled stirred
suspension of 8.3 g (20 mmol) of 5 in 80 mL of dry dioxane
and 18 mL of dry pyridine was added 16 mL of trifluoroacetic
anhydride at 0-5 °C. After the addition was complete, the
reaction mixture was warmed to room temperature, stirred
overnight, and poured onto ice. The product was extracted
three times with EtOAc. The organic layer was washed with
water, 1 M HCl, dilute Na2CO3, and water and dried over
MgSO4. The solvent was removed under vacuum, and the
product was recrystallized from ethanol to give 7 (6.0 g, 79%
yield) as yellow-white needles: mp 216-217 °C; IR (KBr) 2210
(CN) cm-1; 1H NMR (CDCl3) δ 8.19 (s); MS m/z (rel intensity)
380 (M+, 100). Anal. Calcd for C8H3I2N2: C, 25.29; H, 0.53;
N, 7.37. Found: C, 25.61; H, 0.50; N, 7.24.
F igu r e 5. Dependence on temperature of the chemical shift
of internal protons of metal-free phthalocyanines: b, (3,3-
dimethylbutynyl)8PcH2 (23) in C6D6 (different concentrations),
9, in nitrobenzene-d5 (1.1 × 10-3 M); [, in CDCl3 (3.6 × 10-3
M); 2, Pc(hexynyl)8H2 (21) in C6D6 (1.5 × 10-3 M), 1, Pc-
(heptynyl)8H2 (20) in C6D6 (1.5 × 10-3 M).
likely (Figure 5). It should be noted that the aliphatic
protons were unaffected by the effects of both concentra-
tion and temperature.
We know now that the limiting downfield chemical
shift for the aromatic protons of 23 at 10-5 M is 9.92 ppm
in benzene-d6 and 9.73 ppm in nitrobenzene-d6. We can
see that simply raising the temperature of a concentrated
solution is not entirely sufficient to determine the chemi-
cal shifts of “unaggregated” Pcs.
3,4-Diiod op h th a lim id e (3), 3,4-Diiod op h th a la m id e (6),
a n d 3,4-Diiod op h th a lon itr ile (8). When 1 was treated as
above for the preparation of 2, but at 85-90 °C, an inseparable
mixture of 2 and 3 was obtained. This mixture was treated
as above for the preparation of 5 to give another inseparable
mixture of 5 and 6. Finally, treatment of 1.0 g of the mixture
of 5 and 6 as above for the preparation of 7 gave a mixture of
7 and 8. Separation of 7 and 8 on silica gel chromatography
using ethyl acetate-hexane (1:9) as eluent gave 7 (0.8 g, 80%
yield) and 8 (0.1 g, 10% yield): mp 201-202 °C; IR (KBr) 2215
Con clu sion
We have developed reliable syntheses of 4,5-diiodo-
phthalonitrile (7) from which dialkynylphthalonitriles
and dialkylphthalonitriles can be prepared. Some of
these phthalonitriles were condensed to 2,3,9,10,16,-
17,23,24-octaalkynylphthalocyanines and their zinc de-
rivatives. 1H NMR studies of these compounds at
different concentrations and temperatures clearly dem-
onstrate the importance of quoting concentration and
1
(CN) cm-1; H NMR (CDCl3) δ 8.19 (d, J ) 8.7 Hz, 1H), 7.80
(d, J ) 8.7 Hz); MS m/z (rel intensity) 380 (M+, 89). Anal.
Calcd for C8H3I2N2: C, 25.29; H, 0.53: N, 7.37. Found: C,
25.61; H, 0.51; N, 7.24.
4,5-Di(1-octyn yl)p h th a lon itr ile (14). Gen er a l P r oce-
d u r e. To a solution of 500 mg (1.3 mmol) of 4,5-diiodophthalo-
nitrile (7) dissolved in 20 mL of TEA was added 580 mg (5.3
mmol) of 1-octyne (9) and a 5% molar amount of Pd(PPh3)2-
Cl2. The reaction was heated to 110 °C under argon. The
reaction was monitored by TLC using hexane-benzene (1:1)
as eluent. After 30 min, all of the starting phthalonitrile had
completely reacted and the reaction was cooled to room
temperature. The reaction mixture was then suction filtered
on a glass fritted funnel, and the collected precipitate was
washed with diethyl ether until the filtrate was colorless. The
filtrate was then evaporated to dryness under reduced pres-
sure and then preabsorbed onto classical silica gel. A column
using classical silica gel with n-hexane as eluent removed all
unreacted 1-octyne. The solvent was then changed to hexane-
benzene (1:1), and the first fraction collected (280 mg) was the
desired product. This product was further purified by recrys-
tallization in n-hexane to give a waxy yellow solid in 68%
1
temperature values when reporting H NMR spectra of
phthalocyanines. The fact that one alkynyl group causes
a red shift of the Q band by 1 eV allows one to “fine-
tune” this absorption band when designing Pcs.
Exp er im en ta l Section
Gen er a l. See ref 15.
4,5-Diiod op h th a lim id e (2) a n d 4,5-Diiod op h th a lic Acid
(4). To 60 mL of 30% fuming sulfuric acid was added 14.7 g
(0.1 mol) of phthalimide (1) and 25.4 g (0.2 mol) of iodine. The
reaction mixture was heated to 75-80 °C for 24 h. This
mixture was then poured onto 400 g of ice, and the precipitated
solids were filtered off using a funnel with a glass frit. The
solids were washed twice with water, once with a 2% solution
of K2CO3, once with a saturated solution of Na2S2O3, and water
and dried at room temperature. The solids were extracted
with acetone (1 L) in a Soxhlet extractor for 48 h. The
resulting precipitate which formed in the solvent vessel
consisted of 4,5-diiodophthalic acid (4) (mp 220-222 °C (lit.18
mp 221-222 °C)). Compound 4 was filtered from the acetone,
1
yield: mp 42-44 °C; H NMR (CDCl3) δ 7.72 (s, 2H), 2.49 (t,
J ) 7.0 Hz, 4H), 1.59 (m, 4H), 1.45 (m, 4H), 1.31 (m, 8H), 0.90
(t, J ) 6.7 Hz, 6H); IR (KBr) 2930 (s), 2230 (s), 1500 (s) cm-1
;
MS m/z 344 (70), 259 (50), 245 (80), 231 (95), 217 (100), 203
(90), 191 (85), 179 (75). Anal. Calcd for C24H28N2: C, 83.67;
H, 8.14; N, 8.14. Found: C, 83.38; H, 8.23; N, 8.17.
4.5-Di(1-h ep tyn yl)p h th a lon itr ile (15). The same proce-
dure as described above for 14, from 7 and 1-heptyne (10), was

Synthesis of Octaalkynylphthalocyanines
J . Org. Chem., Vol. 61, No. 9, 1996 3039
used to prepare 15 in 80% yield: mp 42-43 oC; 1H NMR
(CDCl3) δ 7.71 (s, 2H), 2.49 (t, J ) 7.0 Hz, 4H), 1.60 (m, 4H),
1.44 (m, 4H), 1.36 (m, 4H), 0.92 (t, J ) 6.8 Hz, 6H); IR (KBr)
2958 (s), 2861 (m), 2229 (s), 1589 (m) cm-1; MS m/z 316 (M+,
73). Anal. Calcd for C22H24N2: C, 83.50; H, 7.64; N, 8.85.
Found: C, 83.75; H, 7.80; N, 8.91.
above using 200 mg of 17 to give 76 mg of 20 in 38% yield: 1H
NMR (benzene-d6, 1.5 × 10-3 M) δ 8.77 (s, 8H), 2.82 (t, J )
6.9 Hz, 16H), 1.92 (m, 16H), 1.67 (q, 16H), 1.5 (m, 16H), 1.1
(t, J ) 7.1 Hz, 24H), -2.82 (bs, 2H); UV-vis λmax (THF) (log
e) 730 (5.47), 694 (5.35), 636 (4.92), 364 (5.32) nm; FABMS
1266 (M + 1). Anal. Calcd for C88H98N8: C, 83.33; H, 7.79;
N, 8.84. Found: C, 82.67; H, 7.12; N, 9.39.
2,3,9,10,16,17,23,24-Octa(1-h exyn yl)ph th alocyan in e (21).
The same method as described above for 19 was used, except
that 100 mg of 16 was used to give 40 mg of 21 in 40% yield:
1H NMR (benzene-d6, 1.5 × 10-3 M) δ 8.73 (s, 8H), 2.83 (t, J )
6.6 Hz, 16H), 1.92 (m, 16H), 1.8 (m, 16H), 1.15 (t, J ) 7.4 Hz,
24H) -2.82 (br, 2H); UV-vis λmax (THF) (log e) 730 (5.22), 694
(5.19), 366 (5.04 nm); FABMS 1154 (M + 1). Anal. Calcd for
C80H82N8: C, 83.25; H, 7.15; N, 8.68. Found: C, 82.98; H, 7.76;
N, 8.68.
2,3,9,10,16,17,23,24-Oct a (1-p en t yn yl)p h t h a locya n in e
(22). The same method as described above for 19 was used
except that 250 mg of 17 was used. As a result of the poor
solubility of the desired Pc 22, it was necessary to use CHCl3
as the eluent for flash column chromatography instead of
benzene. Two columns were run on the crude pigment, and
the final product was reprecipitated from THF/ethanol to give
75 mg of the desired Pc 22 in 30% yield: 1H NMR (benzene-
d6, 1.8 × 10-3 M) δ 8.79 (s, 8H), 2.88 (t, J ) 6.9 Hz, 16H), 2.03
(m, 16H), 1.44 (t, J ) 7.4 Hz, 24 H), -2.64 (br, 2H); UV-vis
λmax (THF) (log e) 728 (5.03), 694 (5.00), 628 (4.55), 363 (4.27)
nm; FABMS 1042 (M + 1).
2,3,9,10,16,17,23,24-Oct a k is(3,3-d im et h yl-1-b u t yn yl)-
p h th a locya n in e (23). The same method as described above
using 100 mg of 18 gave 36 mg of 23 in 36% yield: 1H NMR
(400 MHz, benzene-d6, 1.5 × 10-3 M) δ 9.44 (s, 8H), 1.45 (s,
72H), -1.42 (br, 2H); UV-vis λmax (CHCl3) (log e) 734 (5.32),
694 (5.27), 666 (4.72), 632 (4.59), 368 (5.03), 314 (4.89) nm;
FAB MS (M + 1, 1154). Anal. Calcd for C80H82N8: C, 83.14,
H, 7.16, N, 9.70. Found: C, 83.05; H, 7.36, N, 9.36.
4,5-Di(1-h exyn yl)p h th a lon itr ile (16). The same proce-
dure as described above for 14 using 1 g of 4,5-diiodophthalo-
nitrile (7) and 1-hexyne (11) was used. After the reaction was
complete, the reaction mixture was diluted with toluene and
washed in a separatory funnel once with water, once with
brine, and again with water. The organic layer was then dried
over MgSO4. To the toluene layer was added 1.5 g of classical
silica gel, and the toluene was removed under reduced pres-
sure. A classical silica gel column using toluene as eluent gave
two fractions; the first was unreacted 11 and the second was
1
the desired product 15 in 76% yield: mp 84-86 °C; H NMR
(CDCl3) δ 7.71 (s, 2H,), 2.50 (t, J ) 7.0 Hz, 4H), 1.61 (m, 4H),
1.49 (m, 4H), 0.95 (t, J ) 6.8 Hz, 6H); IR (KBr) 2957 (s), 2873
(m), 2227 (s), 1589 (m) cm-1; MS m/z 288 (M+, 58). Anal.
Calcd for C20H20N2: C, 83.30; H, 6.99; N, 9.71. Found: C,
83.59; H, 7.10; N, 9.78.
4,5-Di(1-p en tyn yl)p h th a lon itr ile (17). The same proce-
dure as described for 16 was used from 7 and 1-pentyne (12)
to give 17 in 82% yield: mp 102-104 °C; H NMR (CDCl3) δ
7.73 (s, 2H), 2.50 (t, J ) 7.0 Hz, 4H), 1.65 (m, 4H), 1.07 (t, J
) 6.9 Hz, 6H); IR (KBr) 2974 (s), 2878 (m), 2230 (s), 1585 (m)
cm-1; MS m/z 260 (M+, 100). Anal. Calcd for C18H16N2: C,
83.04; H, 6.19; N, 10.76. Found: C, 82.88; H, 6.24; N, 10.85.
4,5-Bis(3,3-d im eth yl-1-bu tyn yl)p h th a lon itr ile (18). To
a solution of 60 mL of TEA was dissolved 1 g (2.6 mmol) of
4,5-diiodophthalonitrile (7), 0.53 g (6.5 mmol) of 3,3-dimethyl-
1-butyne (13), CuI (3.75 mmol), and 60 mg of Pd(PPh3)2Cl2.
All reactants were allowed to stir under argon at room
temperature. The reaction was monitored by TLC (with
hexane-benzene (1:1) as the eluting solvent), and after 1 h
most of the starting material had reacted. At this point an
additional 0.3 g of alkyne along with 0.1 g of CuI and 40 mg
of catalyst were added. After 6 h the reaction was complete.
The reaction mixture was suction filtered on a glass fritted
funnel, and the collected precipitate was washed with diethyl
ether until the filtrate was colorless. The filtrate was then
evaporated under reduced pressure to give an orange solid
which was recrystallized from hexane to give 0.65 g of 18 as
white crystals in 85% yield: mp 177-179 °C; 1H NMR (CDCl3)
δ 7.82 (s, 2H), 1.36, (s, 18H); IR (KBr) 2235 cm-1; MS m/z 288
(M+, 78). Anal. Calcd for C20H20N2: C, 83.30; H, 6.99; N, 9.71.
Found C, 83.30; H, 7.12; N, 9.55.
2,3,9,10,16,17,23,24-Octa(1-octyn yl)ph th alocyan in e (19).
To 2.5 mL of 1-pentanol was added 30 mg of lithium metal
and the solution was stirred under argon at 60 °C. After all
of the lithium metal had dissolved, the solution was cooled to
room temperature and 300 mg of 14 was added. The reaction
mixture was then heated to 110 °C under argon. The reaction
was monitored by TLC with benzene as eluent. After 3 h all
of the starting phthalonitrile 14 was gone, and the reaction
was then cooled to room temperature and diluted with 10 mL
of 20% methanol/water. After 90 min the reaction mixture
was then centrifuged and the precipitate collected. The
precipitate was further washed with methanol and collected
by centrifugation. This process was continued until the filtrate
was colorless. At this point the crude pigment was further
purified by flash column chromatography using benzene as
eluent. The first band collected was the desired Pc 19 and
was further purified by a second flash silica gel column to
remove all insoluble impurities. Final purification involved
the reprecipitation of 19 from THF/ethanol which gave 130
mg of the desired Pc in 43% yield: 1H NMR (benzene-d6, 1.5
× 10-3 M) δ 8.77 (s, 8H), 2.8 (t, J ) 6.9 Hz, 16H), 1.9 (m, 16H),
1.65 (m, J ) Hz, 16 H), 1.5 (m, 32H), 1.1 (t, J ) 7.1 Hz, 24H),
-2.38 (br, 2H); UV-vis λmax (THF) (log e) 730 (5.44), 694 (5.38),
636 (4.89), 364 (5.29) nm; FABMS 1379 (M + 1, 40). Anal.
Calcd for C96H114N8: C, 83.59; H, 8.27; N, 8.13. Found: C,
84.15; H, 8.40; N, 8.23.
[2,3,9,10,16,17,23,24-Oct a (1-oct yn yl)p h t h a locya n in -
yl]zin c(II) (24). To 2.5 mL of 1-pentanol was added 30 mg
of lithium metal. The solution was stirred under argon at 60
°C until all of the lithium had dissolved. At this point the
alkoxide solution was cooled to room temperature, and 250
mg of 19 was added. The reaction mixture was then heated
under argon to 110 °C for 3 h. After this time the reaction
temperature was lowered to 80 °C, and 300 mg of Zn(OAc)2
was added. The reaction mixture was allowed to stir for an
o
additional 2 h at 80 C. The reaction mixture was then cooled
to room temperature and diluted with 10 mL of 20% methanol/
water. After being allowed to stand for 90 min the reaction
mixture was centrifuged and the crude zinc Pc 24 collected.
The crude pigment was further washed with 20% methanol/
water until the filtrate was colorless. It was then washed with
methanol and acetonitrile. The crude Pc 24 was further
purified by flash column chromatography with benzene as
eluent, and the first band collected was the desired Pc. This
material was further purified by a second flash silica gel
column with benzene as eluent to give 100 mg of the desired
24 in 40% yield: 1H NMR (benzene-d6, 1.6 × 10-3 M) δ 8.68
(s, 8H), 2.81 (t, J ) 6.8 Hz, 16H), 1.95 (m, 16H), 1.77 (m, 16H),
1.62 (m, 32H), 1.16 (t, J ) 7.1 Hz, 24H); UV-vis λmax (THF)
(log e) 708 (5.57), 636 (4.81), 370 (5.21) nm; FABMS 1444.6
(M + 1). Anal. Calcd for C96H112N8Zn: C, 79.75; H, 7.75; N,
7.75. Found: C, 79.40; H, 7.88; N, 7.73.
[2,3,9,10,16,17,23,24-Octa(1-h eptyn yl)ph th alocyan in yl]-
zin c(II) (25). The same procedure as described above to make
24 was used to give 112 mg of 25 in 45% yield: 1H NMR
(benzene-d6, 1.5 × 10-3 M) δ 8.85 (s, 8H), 2.80 (t, J ) 7.1 Hz,
16H), 1.95 (m, 16H), 1.77 (m, 16H), 1.63 (m, 16H), 1.18 (t, J )
6.9 Hz, 24H); UV-vis λmax (THF) (log e) 706 (5.54), 636 (4.77),
370 (5.12) nm; FABMS 1329.8 (M + 1). Anal. Calcd for
C88H96N8Zn: C, 79.41; H, 7.22; N, 8.42. Found: C, 79.47; H,
7.27; N, 8.16.
[2,3,9,10,16,17,23,24-Octa (1-h exyn yl)p h th a locya n in yl]-
zin c(II) (26). The same procedure as outlined above for 24
was used to give 95 mg of 26 in 38% yield: 1H NMR (benzene-
d6, 1.6 × 10-3 M) δ 8.73 (s, 8H), 2.83 (t, J ) 7.1 Hz, 16H), 1.96
(m, 16H), 1.85 (m, 16H), 1.21 (t, J ) 6.9 Hz, 24H); UV-vis
2,3,9,10,16,17,23,24-Oct a (1-h ep t yn yl)p h t h a locya n in e
(20). Pc 20 was prepared using the same method as described

3040 J . Org. Chem., Vol. 61, No. 9, 1996
max (THF) (log e) 708 (5.52), 634 (4.73), 370 (5.12) nm; FABMS
1216.9 (M + 1). Anal. Calcd for C80H80N8Zn: C, 78.89; H,
6.57; N, 9.20. Found: C, 79.36; H, 6.92; N, 8.72.
Terekhov et al.
λ
4,5-Dip en tylp h th a lon itr ile (30). To 0.3 g (1 mmol) of 17
dissolved in 50 mL of absolute ethanol was added 0.2 g of
palladium on barium sulfate catalyst . The reaction mixture
was placed to a Parr hydrogenation bottle, and the bottle was
installed in a Parr-Shaker apparatus and pressurized to 36
psi. After 1 h the reaction was complete, the catalyst was
filtered, and the solvent was evaporated. The residue was
purified by column chromatography using ethyl acetate and
hexane (1:9) as eluent. The first few fractions, containing the
desired product, were combined and rotary evaporated to yield
white crystals. Recrystallization from hexane gave 0.3 g of
pure 4,5-di(1-pentyl)phthalonitrile29 (30) in 95% yield as white
[2,3,9,10,16,17,23,24-Octa(1-pen tyn yl)ph th alocyan in yl]-
zin c(II) (27). The same procedure as described above for 24
was used, except CHCl3 was used as eluent instead of benzene
for column chromatography to give 95 mg of 27 in 38% yield:
1H NMR (pyridine-d5, 4.5 × 10-4 M) δ 9.79 (s, 8H), 2.84 (t, J
) 7.1 Hz, 16H), 1.96 (m, 16H), 1.27 (t, J ) 6.9 Hz, 24H); UV-
vis λmax (THF) (log e) 706 (5.45), 638 (4.74), 368 (5.14) nm;
FABMS 1108 (M + 1). Anal. Calcd for C72H64N8Zn: C, 78.05,
H, 5.78, N, 10.12. Found: C, 78.16, H, 5.86, N, 10.12.
Syn th esis of [Octa k is(3,3-d im eth yl-1-bu tyn yl)p h th a lo-
cya n iyl]zin c(II) (28). The same procedure as outlined above
was used to give 67 mg of 28 in 25% yield: 1H NMR (400 MHz,
benzene-d6, 2.7 × 10-3 M) δ 9.74 (s, 8H), 1.46 (s, 72H); UV-
vis λmax(CHCl3) (log e) 714 (5.40), 640 (4.61), 370 (5.00) nm;
FAB MS (M + 1) 1216.9. Anal. Calcd for C80H80N8Zn: C,
78.83; H, 6.62; N, 9.19. Found: C, 77.94; H, 6.62; N, 8.57.
4-Iod o-5-(1-octyn yl)p h th a lon itr ile (29). To a solution of
3.8 g (10 mmol) of 4,5-diiodophthalonitrile (7) dissolved in a
40 mL mixture of TEA and DMF (1:1) was added 3 mL (20
mmol) of 1-octyne (9) and a 5% molar amount of Pd(PPh3)2-
Cl2. The reaction mixture was heated to 100 °C under argon
for 1 h, cooled to room temperature, diluted with 200 mL of
ethyl acetate, extracted three times with water, 5% HCl, and
water, a 2% solution of NaHCO3, and water, and dried with
MgSO4. The solvent was evaporated under reduced pressure,
and the oil residue was separated by column chromatography
on silica gel, using hexane and ethyl acetate (19:1), to give
4,5-di(1-octynyl)phthalonitrile (14) (1.4 g, 40%) and 4-iodo-5-
(1-octynyl)phthalonitrile (29) (1.1 g, 30%) as white needles:
crystals: mp 41-43 °C (lit.30 mp 39 °C); H NMR (CH3CN) δ
1
7.70 (s, 2H), 2.68 (t, J ) 7.8 Hz, 4H), 1.93 (m, 4H), 1.56 (m,
4H), 1.33 (m, 4H), 0.90 (t, J ) 4 Hz, 6H); IR (KBr) 2230 (CN)
cm-1; MS m/ z 268 (M+, 85). Anal. Calcd for C18H24N2: C,
80.59; H, 8.95; N, 10.45. Found: C., 80.33; H, 9.23; N, 10.24.
4,5-Bis(3,3-dim eth ylbu tyl)ph th alon itr ile (31). The same
method as described above for 30 was used except that 1.44 g
(5 mmol) of 18 was used and gave us 1.40 g in 95% yield of
pure 4,5-di(3,3-dimethylbutyl)phthalonitrile (31) as white crys-
tals: mp 127-129 °C; IR (KBr) 2235 (CN) cm-1; 1H NMR (400
MHz, CDCl3) δ 7.56 (s, 2H), 266 (m, 44), 1.44 (m, 4H), 1.02 (s,
18H); MS m/z 292 (M+, 82). Anal. Calcd for C20H28N2: C,
81.03; H, 9.52; N, 9.45. Found: C, 81.28; H, 9.51; N, 9.46.
Ack n ow led gm en t. We wish to thank the Natural
Sciences and Engineering Research Council of Canada
for financial support and Bob Suchozaks for some
experimental work.
J O9521662
1
mp 46-47 °C; IR (KBr) 2256, 2210 cm-1; H NMR (CDCl3) δ
8.19, (s, 1H), 7.21, (s, 1H), 2.86 (t, J ) 7.0 Hz, 2H) 2.69, (m,
2H), 1.52 (m, 2H) 1.33, (m, 2H) 0.93, (t, J ) 6.8 Hz, 3H); MS
m/z 362 (M+, 10). Anal. Calcd for C16H15N2I: C, 53.06; H,
4.17; N, 7.73. Found: C, 53.36; H, 4.10; N, 7.56.
(29) Engel, M. K.; Bassoul, P.; Bosio, L.; Lehmann, H.; Hanack, M.;
Simon, J . Liq. Cryst. 1993, 15, 709.
(30) Hanack, M. Private communication.