Synthesis and photophysical properties of novel phthalocyanine- perylenediimide-phthalocyanine triad and phthalocyanine-perylenediimide dyads

Article abstract of DOI:10.1039/c4ra03552f

A series of novel multi-component chromophores, one phthalocyanine- perylenediimide-phthalocyanine triad and two phthalocyanine-perylenediimide dyads, were synthesized by covalent linkage between phthalocyanines and perylene-3,4,9,10-bis(dicarboximide) at the bay position of perylene core in one condensation reaction. The photophysical properties of the dyes were presented with wider light absorption from 300 to 800 nm and discussed by interpretation and correlations with previous dyes. Density functional theory at the B3LYP level with 6-31G(d) was performed for geometry and energy optimization. Furthermore, a substitution and elimination reaction at the perylene bay position by using 1,8-diazabicyclo[5,4,0]undec-7-ene as catalyst was performed and its probable mechanism discussed. the Partner Organisations 2014.

Full text of DOI:10.1039/c4ra03552f

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Synthesis and photophysical properties of novel
phthalocyanine–perylenediimide–phthalocyanine
triad and phthalocyanine–perylenediimide dyads†
Cite this: RSC Adv., 2014, 4, 25616
a
b
c
c
a
*
*
Xiaobo Sun, Wenfeng Qiu, Donghui Wei, Mingsheng Tang and Lin Guo
A series of novel multi-component chromophores, one phthalocyanine–perylenediimide–phthalocyanine
triad and two phthalocyanine–perylenediimide dyads, were synthesized by covalent linkage between
phthalocyanines and perylene-3,4,9,10-bis(dicarboximide) at the bay position of perylene core in one
condensation reaction. The photophysical properties of the dyes were presented with wider light
absorption from 300 to 800 nm and discussed by interpretation and correlations with previous dyes.
Density functional theory at the B3LYP level with 6-31G(d) was performed for geometry and energy
optimization. Furthermore, a substitution and elimination reaction at the perylene bay position by using
1,8-diazabicyclo[5,4,0]undec-7-ene as catalyst was performed and its probable mechanism discussed.
Received 18th April 2014
Accepted 27th May 2014
DOI: 10.1039/c4ra03552f
www.rsc.org/advances
characteristic electronic absorption from the ultraviolet to
visible region. And, they have been proven to be good building
Introduction
blocks for constructing supramolecular systems because their
physical and physicochemical properties could be easily tuned
by multiple modication possibilities of chemical functionali-
zation, such as metal center, peripheral positions, and axial
positions to metal.7
On the other hand, perylenediimide (PDI) unit is well-known
electron-accepting chromophore. PDI derivatives represent a
class n-type semiconductors with relatively high electron
affinity and excellent transport property.8 They have a charac-
teristic absorption in the visible region. PDI based materials
have been widely used in the elds of solar cells, eld-effect
transistor and optical switches, etc.9
Multifunctionality, as a leading strategy in building electron
donor and acceptor system, has shown much more interest for
photochemistry, photophysics and energy conversion. The
systems describe the basics in photoinduced charge separation,
and also play a key role in organic photovoltaic property.10
Wasielewski et al. reported an electron donor–acceptor–donor
(D–A–D) molecule based on PDI unit, which synthesized by
covalent linking of the electron-donor porphyrins with PDI
through its imide position. The D–A–D type molecules exhibit
interesting properties originating from the photoinduced elec-
tron transfer.11 Recently, Torres et al. have incorporated PDI
unit as the oxidizing complement of phthalocyanines, which
towards versatile D–A arrays to give rise to energy transfer
products and/or long-lived radical ion-pair states.12
Synthesis of giant multi-component molecular chromophores
has continuously attracted much attention due to their unique
photophysical and photochemical properties.1 The energy,
charge and photon-transfer processes in these multi-chromo-
phore molecular systems are promising and worthy of system-
atic research to develop highly efficient photoelectronic
devices.2 Photoinduced electron transfer in organic molecules
containing both electron-donating and electron-accepting
chromophores has been studied extensively.3 The efficiency of
those processes is governed by the selected building block
functionalities, linkers and geometrical arrangements.4 There
has been intensive research in the synthesis and photophysical
study of donor–acceptor chromophores using different
coupling partners for applications in articial photosynthetic
systems and photoinduced charge separation.5
As promising molecular donors for articial photosynthetic
apparatus, phthalocyanines (Pcs) have excellent optoelectronic
properties as well as good chemical and physical stability. They
have been widely used in the elds of solar cells, nonlinear
optics, and photocatalysts, etc.6 The big planar p-conjugated
system made Pcs as excellent electron-donating chromophores
and high charge carrier mobility organic semiconductors with
aBeijing Key Laboratory of Bio-Inspired Energy Materials and Devices, School of
Chemistry and Environment, Beihang University, Beijing 100191, P. R. China.
E-mail: sunxb@buaa.edu.cn; guolin@buaa.edu.cn
bInstitute of Chemistry, Chinese Academy of Sciences, Beijing 100080, P. R. China
cThe College of Chemistry and Molecular Engineering, Zhengzhou University,
Zhengzhou, Henan Province 450001, P. R. China
In the past years, we have paid more attention on synthesis
and photophysical properties of large p-extended molecular
materials with Pcs or PDI groups as functional blocks. Several
Pcs-based functional materials have been synthesized with
symmetrically and asymmetrically substituted structures, which
† Electronic supplementary information (ESI) available. See DOI:
10.1039/c4ra03552f
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have been used as active materials for electronic devices, such
The synthetic route and molecular structures of triad and
as gas sensor, organic eld-effect transistor, molecular rectier dyads are shown in Scheme 1. The rst phthalonitrile function
and organic light-emitting diodes.13 For PDI part, we also got group, 4,5-di-n-octyloxyphthalonitrile, was synthesized with
some progresses on synthesis of multinuclear systems. We three steps according to the previous literature.20 The second
rstly incorporated oligothiophene moieties to the bay posi- phthalonitrile function group (compound 3) was prepared by
tions of PDI core.14 Later, a tetra-substituted functional PDI unit combination of two intermediates (compound 1 and 2). 3-(2-
by aryl groups at the four bay positions and the corresponding Ethylhexyloxy)-6-hydroxyphthalonitrile 1 was synthesized from
derivatives were synthesized with high yields.15 Our extensive the controlled alkylation of 2,3-dicyano-1,4-dihydroquinone
experiences in Pcs and PDI have motivated us to use them as with 2-ethylhexylbromide in molar ratio of 1 : 1. Aer reaction,
building blocks to design novel electron donor–acceptor func- we can easily remove the di-alkyl substituted product by stan-
tionalized chromophores.
dard column chromatography, then a pale yellow 1 was ach-
Up to now, a few Pcs–PDI based donor–acceptor multi- ieved with yield 53% by using methanol as additional partly
chromophores have been reported.5,16 However, most of them eluent. And, dibrominated PDI derivative 2 was obtained by
were presented that the two chromophores were connected bromination of perylene bisanhydride, followed by imidation in
through the PDI imide position. The modication at the PDI bay propionic acid.14 Then, compound
2 was reacted with
position is very scarce due to the great difficulties in both compound 1 to generate the 1,7-disubstituted PDI derivative 3.
synthesis and purication.5b,17 The key point for introducing The introduction of four alkyl chains is very helpful to improve
groups at PDI bay positions is to make use of an electronic the solubility of PDI derivative, so compound 3 could be easily
coupling to enhance electron mobility through strong p–p puried by silica gel column chromatography. Consequently, a
stacking interactions between the planar PDI moieties, and catalytic amount of DBU was added to a mixture of 4,5-di-n-
even to exploit an ultrafast photoinduced charge separated octyloxyphthalonitrile, compound 3, Zn(OAc)2 and n-hexanol.
state.18 However, the introduction of substituent at the imide The resultant mixture was stirred and heated at 140 ꢀC for 8 h to
position would not signicantly work on electronic structures of afford the compounds 4, 5 and zinc phthalocyanine ZnPc(OR)8
perylene unit due to the frontier molecular orbital nodes with as we supposed.
the imide nitrogen atoms.3d,19
Separation and purication. As we thought, the separation
In this study, we expect to incorporate two functional chro- and purication of mixture is quite difficult due to their similar
mophores Pcs and PDI into one molecular system through PDI molecular structures with high molecular mass. Silica gel
bay positions.
A covalently linked phthalocyanine–peryl- column chromatography was rstly carried out to separate the
enediimide–phthalocyanine triad and two phthalocyanine– crude mixtures. A rst pink fraction with a small amount of
perylenediimide dyads have been synthesized. The metal sample was shown, in which compound 7 was assigned. The
phthalocyanine units are linked to the bay position of the per- second black-like fraction with large amount samples was
ylene core. The substitution and elimination reactions at the collected until the eluted-out solution started to show clear
PDI bay position will be discussed. The steady-state absorption green color, which contained the target D–A products as we
properties and geometry and energy optimization are presented supposed. The third green fraction should belong to the
for these multifunctional chromophores.
symmetrical product ZnPc(OR)8. Then, the crude products in
the second fraction were further puried by size-exclusion
chromatography (Bio-Beads SX-2) with THF as eluent.21 By this
method, the compounds could be isolated based on the
different molecular sizes. A proper amount of the sample
Results and discussion
1. Synthesis and characterization
Synthesis. The target molecule, Pc–PDI–Pc triad 4 (Scheme solution was eluted in the column, then several new colorful
1), is composed of an electron rich phthalocyanine subunit bands were appeared: the rst brown-black band, the second
bearing several electron-donating alkoxy groups linked to a purple one and the third green one (ZnPc(OR)8). In order to
strongly electron-demanding PDI substituted at the 1,7-bay obtain high purity compounds, each colorful fraction was per-
positions. For most of PDI derivatives, multi-component chro- formed over 5 times by the size exclusion column. By surprise, a
mophores are directly assembled between suitable Pc chromo- purple solid was separated from the second fraction, which did
phore and PDI moiety by covalent coupling reaction though the not agree with compounds 4 and 5. Aer characterization, a new
PDI imide positions. It is hard to construct multi-components compound 6 is conrmed as shown in the Scheme 1. As mass
at the PDI bay positions due to the reactive activity and large spectra indicated, the rst brown-black band was found to be a
steric hindrance.5b,17 Torres et al. rstly reported a conjugated mixture of compounds 4 and 5, which could not be separated
donor–acceptor array composed of two Pc moieties connected even by Bio-beads column. Fortunately, compounds 4 and 5
to the bay positions of PDI moiety by using palladium-catalyzed showed totally different solubilities in the mixed solvents (THF–
coupling reaction.5b Here, we chose another approach to fabri- CH3OH 1 : 2 v/v). So, the mixture containing 4 and 5 was dis-
cate the system: rst, the phthalonitrile function group was solved in 10 mL of THF, then 20 mL of CH3OH was added
connected to the 1,7-bay positions of PDI moiety; then, two slowly. Aer the resultant mixtures were kept overnight, a
phthalonitrile function groups (octyloxyphthalonitrile group brown precipitate appeared. The brown precipitate was ltered
and PDI modied phthalonitrile groups) were used to prepare with remaining a neat green ltrate solution. Then, CH3OH was
asymmetric Pcs.
added to the green ltrate to give a green precipitate. These
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Scheme 1 Synthetic route and reagents.
precipitation procedures were repeated by several times until reaction on the phthalonitrile-like substituent. Finally, a
the ltrate showed colorless. Finally, high purity compounds 4 –OC6H13 group would be introduced to the PDI bay position.
and 5 were successfully isolated as the brown and green color
In order to conrm this deduction, a reference reaction has
solids.
been designed and proceeded as shown in Scheme 2. In the
Synthesis mechanism. In the condensation reaction, excess modeling chemical reaction, compound 3, a catalytic amount of
4,5-di-n-octyloxyphthalonitrile and compound 3 should be DBU and n-C6H13OH were mixed under the same reaction
assembled to afford compounds 4,
5 and by-product conditions as described previously. With this reaction,
ZnPc(OR)8). However, a new compound 6 and a trace amount of compound 7 was formed by double replacement reaction at 1,7-
7 were isolated accidentally in the reaction aer the careful bay positions with relative high yield. Meantime, a small
multi-step purication. It is easy to understand the generation amount of compound 8 was isolated from single replacement
of products 4 and 5, but it is hard to explain the formation of reaction. The most likely mechanism for the single replacement
compounds 6 and 7. As known, the substituents at the PDI bay reaction can be explained as: the second bay position of 1,7-
position are possible to be attacked by basic reagents.22 The disubstituted PDI (as compound 8) was passivated aer one bay
strong electron-withdrawing –CN groups in compound 3 make position of 1,7-disubstituted PDI (as compound 3) was
the phthalonitrile-like part as a leaving group under basic substituted by the –OC6H13 group. It is much more difficult to
conditions. In this case, the basic DBU may react with the continue replacement reaction due to the electron-donating
solvent (n-hexanol) to generate C6H13Oꢁ ion, and then C6H13Oꢁ effect of –OC6H13 group. Therefore, both compound 7 and 8
ions attack the PDI bay positions, which lead to a elimination could be coexisted. The mechanism can also be used to explain
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Scheme 2 Reference reaction to synthesize compounds 7 and 8.
the generation of compound 5 with one phthalonitrile function
group remaining. As shown in the IR spectra, the absorption
peak of –CN group is detected near 2230 cmꢁ1 for compounds 5
and 8, which is a direct evidence of the existence of –CN group
in the molecules.
Characterization. Three D–A compounds 4–6 have been
synthesized by using one condensation reaction. The yield for
compounds 4–6 is 3%, 4% and 7% (calculation based on 3),
respectively. Though the yield of each product is low, the total
yield (17% ¼ 3% ꢂ 2 + 4% + 7%) is a typical for asymmetrical
phthalocyanines if we consider all compounds as related
asymmetrical phthalocyanines. In order to conrm the molec-
ular structure directly, MALDI-TOF MS is used as an effective
technique for the determination of high molecular mass
compounds. Compounds 4–6 show clear molecular ionic peaks
(M+ or M++1) at m/z 3593.4, 2372.1, and 2201.6, respectively (see
the spectra in ESI†). For compound 4, the M+ peak is more
difficult to be detected due to its much higher molecular mass.
So, a theoretically calculated pattern from the molecular
formula C216H294N18O20Zn2 was used to compare with the
experimental isotopic distribution of the M+ peaks. A good
agreement was found to further conrm the molecular struc-
ture for compound 4 (see the spectrum in ESI†). For NMR
characterization, poorly informative 1H NMR spectra of
compounds 4–6 were shown as very broad peaks of aromatic
protons due to their complicated molecular structures and
aggregation trend between large molecules in solution.5b
Therefore, elemental analysis is needed to further conrm the
purities of the compounds. Other structural evidences can be
checked in IR spectra. All the compounds 3–8 show character-
istic C]O stretching vibration absorptions between 1710 and
1650 cmꢁ1, which can be assigned to the imide units. It is also
worthy to be mentioned that the –CN group absorption is
detected near 2230 cmꢁ1 for compounds 3, 5 and 8, which is the
direct evidence for the existence of –CN group in the molecules.
On the contrary, there was no –CN stretching absorption found
for compounds 4, 6, and 7 in the IR spectra.
Fig. 1 Normalized UV-vis absorption spectra of compounds 3 (purple
line), 4 (red line), 5 (green line), 6 (blue line) and ZnPc(OR)8 (black line)
in CHCl3 at room temperature.
reference compound ZnPc(OR)8 exhibits characteristic absorp-
tion of metal Pcs with the strong Q-band absorption located at
678 nm and the B-band absorption at 356 nm.23 The shoulder
peak at 612 nm comes from the strong p–p aggregation effect
between planar phthalocyanine molecules. The spectrum of
compound 3 illustrates the characteristic absorption of the bay
position substituted PDI derivatives. From 450 nm to 600 nm,
the absorption bands of compound 3 are located at 533 and 497
nm, which attributed to the symmetrically substituted perylene
imides.5c Compounds 4–6 strongly aggregate due to their big p-
structure, as is clearly evidenced by its broad, abnormally low
intense Q-band.5b The use of diluted solutions produces pho-
tophysical study (10ꢁ6 M). The UV-vis spectra of compounds 4–6
clearly show the characteristic absorptions of the combination
of phthalocyanine ZnPc(OR)8 and PDI derivative 3 (see Table 1).
The Q-band absorptions of compounds 4–6 are located at 677
and 699 nm as well as the shoulder peaks at 645 nm and the B-
band absorptions at 357 nm. These characteristic absorptions
undoubtedly come from those of the phthalocyanine parts,
which compared those to maxima at 356 and 678 nm for the
phthalocyanine fragment ZnPc(OR)8. Importantly, the large
splitting of the Q-bands (677 and 699 nm), as well as broadening
peaks, indicate a strong coupling of transition dipoles.5b Kasha
2. Steady-state absorption properties
Fig. 1 shows the normalized UV-vis absorption spectra of the
triad and dyads 4–6 together with those corresponding to the
fragments, PDI derivative 3 and ZnPc(OR)8. The spectrum of
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Table 1 Steady-state UV-vis absorption data for compounds 3–8 and
ZnPc(OR)8 in CHCl3
phenomenon is achieved that the PDI transitions are blue
shied to 502 nm and 470 nm in the reference to compound 3
and 7. Part of these changes arise from the bay substituted PDI,
which has a strong inuence on the planarity of the PDI chro-
mophore.5b And, all compounds 3–8 could be studied as donor–
acceptor–donor (D–A–D) structures with PDI or phthalonitrile
as acceptors and Pc part or –OC6H13 group as donors.
For compounds 4–6, their Q-band and B-band absorption are
also quite similar to each other, but PDI absorptions show very
different behaviors as well as the color in solution and solid
state. Compound 5 is special because of its bearing an electron-
donating Pc unit and an electron-accepting unit (phthalonitrile)
at the same time, which could be viewed as donor–acceptor–
Sample
labs (nm)
3
4
5
6
7
8
497
520
470
528
532
532
533
564
502
570
573
574
357
357
357
612
612
612
645
645
650
677
677
677
699
698
699
430
503
ZnPc
356
612
650
678
et al. have developed the simple point-dipole exciton coupling
theory to position that the transition dipoles of two identical
chromophores.24 The stacked geometry results in exciton
coupling of the two transition dipoles causing the lowest-energy
electronic transition of the dimer to split into two bands.16a
Moreover, the broad band near 645 nm of compounds 4–6 is
also characteristic of zinc phthalocyanine H-aggregates, which
have been revealed by several groups.25
acceptor (D–A–A) type. A set of absorption bands of 5 at lmax
¼
502, 470, and 430 nm are blue shied. This result could be
possibly attributed to strong electronic communication from
ZnPc (i.e., electron donor) to PDI (i.e., acceptor) units.
3. Molecular modeling
For PDI transitions, more information is shown in the region
from 400 to 600 nm, where compounds 4–6 exhibit the obvious
absorption character. The location and pattern of the absorp-
tion bands in compounds 6 (lmax at 570 nm, 528 nm) and 4
To gain further insight into the geometric and electronic
properties of these dyes, density functional theory (DFT) at the
B3LYP level with 6-31G(d) as the basis set is used for geometry
and energy optimization. The optimized structures of the
respective molecules and the distribution of frontier orbitals
were calculated for compound 4 (double bay position substit-
(lmax at 564 nm, 520 nm) are quite similar to those of 7 (lmax
¼
573 nm, 532 nm, see Fig. S4†). But, compared with those of
compound 3, the PDI transitions are red shied with 40 nm for
both peaks. However, for the compound 5, a totally different
uent, Pc–PDI–Pc) and compound
6 (single bay position
substituent, Pc–PDI), which shown in Fig. 2. The HOMO-level of
Fig. 2 The optimized geometric structure of compounds and their frontier orbital plots were calculated by DFT at the B3LYP/6-31G(d) level.
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compound 4 and 6 is dominated by the molecular orbitals of the
phthalocyanine fragment. On transition to the LUMO-level, the
molecular orbitals of the perylene moiety are dominant, as
expected. The compounds show that molecular orbital ampli-
tude plots are typical D–p–A system with dominant electron
distribution around the donor moiety in the HOMO-level and
dominant electron distribution around the acceptor moiety in
the LUMO-level.26 No interaction among the subunits could be
predicted due to the absence of any orbital overlap.5c The
calculated HOMO and LUMO energy values were found to be
ꢁ4.60 and ꢁ2.96 eV for compound 4, and ꢁ4.63 and ꢁ3.01 eV
for compound 6, separately. Compound 4 and 6 show similar
energy level, and this trend is in agreement with Valiyaveettil's
reports on triphenylamine bay substituent PDI dyes.27
Synthesis and characterization of compounds
4,5-Di-n-octyloxyphthalonitrile.20 FT-IR (KBr, cmꢁ1) n 2231
(s, –CN); 1H NMR (400 MHz, CDCl3, 25 ꢀC): d ¼ 7.11 (S, 2H, Ar-
H), 4.04 (t, J ¼ 6.5 Hz, 4H, O–CH2), 1.85 (m, 4H, CH2), 1.45
(m, 4H, CH2), 1.33 (m, 16H, CH2), 0.89 (m, 6H, CH3); MS (EI+):
m/z 384 (M+); Anal. calcd for (C24H36N2O2): C, 74.96; H, 9.44; N,
7.28. Found C, 75.14; H, 9.57; N, 7.39.
3-(2-Ethylhexyloxy)-6-hydroxyphthalonitrile (1). A mixture of
1.60 g (10 mmol) 2,3-dicyano-1,4-dihydroquinone, 1.93 g
(10 mmol) 2-ethylhexylbromide, 1.38 g (10 mmol) K2CO3 and
15 mL DMF was stirred vigorously under nitrogen atmosphere
at room temperature for 24 h. The resultant mixture was poured
into 100 mL H2O, it was then extracted by the mixed solvent
(petroleum ether–ethyl acetate 4 : 1 v/v, 100 mL ꢂ 3). The
organic layers were combined and washed by water. The further
purication was carried out by column chromatography (silica
gel, 100–200 mesh). By using dichloromethane as eluent, di-
alkyl substituted product was separated, then eluting with
dichloromethane–methanol (20 : 1 v/v) gave compound 1 as a
pale yellow solid aer removing the solvent (1.40 g, 53%). 1: FT-
IR (KBr, cmꢁ1) n 3265 (br, –OH), 2246 (s, –CN); MS (EI+): m/z 272
(M+); 1H NMR (400 MHz, CDCl3, 25 ꢀC): d ¼ 7.30 (d, J ¼ 9.3 Hz,
1H, Ar-H), 7.18 (d, J ¼ 9.4 Hz, 1H, Ar-H), 7.15–6.30 (s, br, 1H,
–OH), 3.95 (m, 2H, O–CH2), 1.76 (m, 1H, CH), 1.52 (m, 4H, CH2),
1.31 (m, 4H, CH2), 0.92 (m, 6H, CH3); elemental analysis (%),
calcd. for (C16H20N2O2): C, 70.56; H, 7.40; N, 10.29. Found: C,
70.90; H, 7.47; N, 10.27.
N,N0-Di(2-ethylhexyl)-1,7-dibromoperylene-3,4,9,10-bisdicar-
boximide (2). A solution of 1,7-dibromo-perylene tetracarboxylic
acid anhydride 2.0 g (3.6 mmol), 2-ethylhexylamine 1.9 g (15
mmol, excess) in propionic acid was reuxed for 16 h. Rotary
evaporation to remove the solvent, then the compound was
puried by column chromatography (silica gel, dichloro-
methane–petroleum ether 4 : 1 v/v) to yield 2 as a red solid (2.1
g, 78%). 2: UV/Vis (CHCl3) lmax 524, 489, 272 nm; FT-IR (KBr,
Conclusion
We have successfully synthesized one phthalocyanine–per-
ylenediimide–phthalocyanine triad and two phthalocyanine–
perylenediimide dyads. The combination of the silica gel, size-
exclusion column chromatographys and fractionating precipi-
tation is testied as an effective method to separate and purify
the high molecular mass compounds with similar molecular
structures. By chemical bonding, these compounds possess a
wider light absorption from 300 to 800 nm with apparent
combination of the properties of phthalocyanine and per-
ylenediimide fragments. A large splitting of the Q-bands indi-
cates a strong coupling of transition dipoles in this molecular
system. Possible investigation of the photoinduced electron-
and energy-transfer process of the triad and dyads are worthy of
further study.
Experimental section
Materials
Normal chemicals were purchased from Aldrich and used as cmꢁ1) n 2958, 2929, 2860, 1702 (s, C]O), 1662 (s, C]O), 1591,
received. Solvents and other normal reagents were obtained 1393, 1333, 1239; MSꢀ(MALDI-TOF): m/z 771.1 (M++1); H NMR
1
from the Beijing Chemical Plant. Solvents for reactions and (400 MHz, CDCl3, 25 C): d ¼ 9.43 (d, J ¼ 8.2 Hz, 2H, perylene-
photophysical measurements were all distilled aer dehydra- H), 8.87 (s, 2H, perylene-H), 8.65 (d, J ¼ 8.1 Hz, 2H, perylene-H),
4.09–4.19 (m, 4H, –CH2–N), 1.92–1.96 (m, 2H, –CH–), 1.32–1.42
(m, 16H, –CH2–), 0.95 (t, 6H, –CH3), 0.90 (t, 6H, –CH3); 13C NMR
(400 MHz, CDCl3, 25 ꢀC): d ¼ 162.8 (C]O), 162.3 (C]O), 137.8,
132.3, 132.2, 129.6, 128.7, 128.1, 126.5, 122.9, 122.5, 120.7, 44.4,
tion according to conventional methods. 1,8-Diazabicyclo[5,4,0]
undec-7-ene (DBU), 2-ethylhexylbromide, 2-ethylhexylamine and
1-methyl-2-pyrrolidinone (NMP) were purchased from Acros.
Perylene-3,4,9,10-tetracarboxylic acid anhydride was purchased
from Aldrich. 2,3-Dicyano-1,4-dihydroquinone was purchased 37.9, 30.7, 28.6, 23.9, 23.0, 14.1, 10.5; elemental analysis (%),
from TCI. Bio-Beads SX-2 was bought from Bio-Rad Co.
calcd. for (C40H40Br2N2O4): C 62.19, H 5.22, N 3.69; found: C
62.30, H 5.23, N 3.44.
Synthesis of compound 3. A mixture of compound 2 (770 mg,
1.0 mmol), 1 (816 mg, 3.0 mmol, excess), K2CO3 (420 mg, 3.0
mmol) and NMP 8 mL was stirred and heated at 80 ꢀC for 24 h
under N2 atmosphere. Aer cooling to room temperature, the
reaction mixture was poured into 200 mL of water and stand for
hours before ltration. The lter residue was washed by water
repeatedly to ensure the completed removal of NMP. The
compound was puried by column chromatography (silica gel,
dichloromethane) two times to yield 3 as red-orange powder
(690 mg, 60%). 3: UV/Vis (CHCl3) lmax 533, 497 nm; FT-IR (KBr,
Instrumentation
NMR spectra were measured with Bruker 400 MHz spectrome-
ters. Mass spectra were recorded on AEI-MS50-MS spectrometer
for EI MS and Bruker BIFLEXIII spectrometer for matrix assisted
laser desorption–ionization with time of-ight mass spectrom-
etry (MALDI-TOF-MS). Elemental analysis was performed on
Carlo-Erba-1106 instrument. Infrared spectra were determined
with Pekin-Elmer Tensor 27 spectrometer. Electronic absorp-
tion spectra were measured on a Hitachi (model U-3010) UV-vis
spectrophotometer.
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cmꢁ1) n 2959, 2930, 2864, 2234 (s, –CN), 1701 (s, C]O), 1661 (s, 1494, 1463, 1383, 1335, 1278, 1107, 1038; MS (MALDI-TOF): m/z
C]O), 1597, 1480, 1461, 1406, 1335, 1255, 1056; MS (MALDI- 3593.4 (M+); elemental analysis (%), calcd. for (C216H294
-
TOF): m/z 1154.9 (M+), 1177.9 [M + Na]+; 1H NMR (400 MHz, N18O20Zn2$H2O): C, 71.83; H, 8.26; N, 6.98; found: C, 71.69; H,
CDCl3, 25 ꢀC): d ¼ 9.40 (d, J ¼ 8.4 Hz, 2H, perylene-H), 8.65 (d, 8.02; N, 6.75.
J ¼ 8.3 Hz, 2H, perylene-H), 8.12 (s, 2H, perylene-H), 7.36 (d, J ¼
Compound 5 (31 mg, 4%, calculation based on 3). UV/Vis
9.4 Hz, 2H, Ar-H), 7.28 (d, J ¼ 7.8 Hz, 2H, Ar-H), 4.10 (m, 4H, N– (CHCl3) lmax 698, 677, 645, 612, 502, 470, 430, 357 nm; FT-IR
CH2), 4.04 (m, 4H, O–CH2), 1.84 (m, 4H, CH), 1.55 (m, 16H, (KBr, cmꢁ1) n 2956, 2927, 2856, 2230 (s, –CN), 1702 (s, C]O),
CH2), 1.36 (m, 16H, CH2), 0.94 (m, 24H, CH3); 13C NMR (400 1663 (s, C]O), 1597, 1495, 1463, 1382, 1335, 1277, 1106, 1038;
MHz, CDCl3, 25 ꢀC): d ¼ 163.1, 162.7, 158.9, 153.6, 149.7, 132.3, MS (MALDI-TOF): m/z 2372.1 (M++1); elemental analysis (%),
130.8, 129.6, 129.0, 126.1, 125.4, 124.3, 123.7, 122.7, 121.9, calcd. for (C144H186N12O14Zn$H2O): C, 72.29; H, 7.92; N, 7.03;
118.9, 112.1, 112.1, 109.6, 106.2, 72.9, 44.5, 39.2, 37.9, 30.7, 30.2, found: C, 72.52; H, 7.77; N, 6.81.
29.0, 28.7, 24.0, 23.7, 23.0, 22.9, 14.1, 14.0, 11.1, 10.6; elemental
analysis (%), calcd. for (C72H78N6O8): C, 74.84; H, 6.80; N, 7.27; (CHCl3) lmax 699, 677, 650, 612, 570, 528, 357 nm; FT-IR (KBr,
found: C, 74.66; H, 6.82; N, 7.15.
cmꢁ1) n 2956, 2926, 2857, 1695 (s, C]O), 1657 (s, C]O), 1593,
Synthesis of compound 4, 5, and 6. Five droplets of DBU 1496, 1463, 1384, 1334, 1278, 1107, 1038; MS (MALDI-TOF): m/z
was added to a mixture of 3 (410 mg, 0.35 mmol), 4,5-di-n- 2201.6 elemental analysis (%), calcd. for
(M+);
Compound 6 (55 mg, 7%, calculation based on 3). UV/Vis
octyloxyphthalonitrile (1.090 g, 2.83 mmol, 8 equiv.), anhydrous (C134H180N10O13Zn$H2O): C, 72.42; H, 8.25; N, 6.30; found: C,
Zn(OAc)2 (160 mg, 0.88 mmol, 2.5 equiv.), and n-hexanol (10 mL) 72.17; H, 7.96; N, 6.30.
under nitrogen atmosphere. The resultant mixture was stirred
Characterization of ZnPc(OR)8. UV/Vis (CHCl3) lmax 678, 650,
and heated at 140 ꢀC for 8 h. Aer cooling to room temperature, 612, 356 nm; FT-IR (KBr, cmꢁ1) n 2924, 1605, 1496, 1461, 1384,
the dark green reaction mixture was poured into 200 mL 1279, 1202, 1107, 1046; 1H NMR (CDCl3, 400 MHz): d ¼ 8.10 (s,
methanol, and it was put to stand for hours and then ltered. br, 8H, Ar-H), 4.49 (s, br, 16H, O–CH2), 2.15 (s, br, 16H, CH2),
The lter residue was washed by methanol completely. Silica gel 1.79 (m, 16H, CH2), 1.70–1.10 (m, 64H, CH2), 0.99 (s, br, 24H,
column chromatography (100–200 mesh, diameter 80 mm, CH3); MS (MALDI-TOF): m/z 1599.7 (M+); elemental analysis (%),
length 20 cm) was carried out to purify the product roughly by calcd. for (C96H144N8O8Zn): C, 71.90; H, 9.05; N, 6.99, found C,
the use of chloroform as eluent. The rst band was pink and 71.86; H, 8.95; N, 6.93.
proved to contain small amount of compound 7. The second
Reference reaction: synthesis of compounds 7 and 8. A
black-like band was gathered until the eluted-out solution solution of compound 3 (100 mg), three droplets of DBU and
became clear green, so as to ensure the overlapped bands to be 5 mL of n-hexanol was stirred under nitrogen atmosphere at
ꢀ
gathered. The third band was the main product and character- 140 C for 8 h. Aer cooling to room temperature, the mixture
ized to be ZnPc(OR)8. Then, the crude products in the second was evaporated at reduced pressure to remove all the solvent.
band were further puried by size-exclusion chromatography The solid residue was puried by silica gel column chroma-
(Bio-Beads SX-2, column size: diameter 50 mm, length 80 cm). A tography by using dichloromethane–hexane 4 : 1 v/v as eluent.
proper amount of the sample solution in THF was put onto the The rst pink band was collected as compound 7. Then,
column and eluted with THF, then several new bands appeared, dichloromethane was used to elute out the third band, which
the rst band was brown-black, the second purple band, and the was characterized to be compound 8.
third green one. The bands with same colour were collected and
Compound 7 (25 mg, 35%, calculation based on 3). UV/Vis
combined, and put into Bio-beads column again. The size (CHCl3) lmax 573, 532 nm; FT-IR (KBr, cmꢁ1) n 2958, 2860, 1694
exclusion column separation was performed over 5 times for (s, C]O), 1653 (s, C]O), 1598, 1436, 1336, 1270; 1H NMR
ꢀ
each sample to obtain high pure compounds. In our isolation (400 MHz, CDCl3, 25 C): d ¼ 9.37 (d, J ¼ 8.4 Hz, 2H, perylene-
process, the second band was enriched compound 6, so the H), 8.37 (d, J ¼ 8.4 Hz, 2H, perylene-H), 8.19 (s, 2H, perylene-H),
compound 6 could be isolated ideally to give a purple solid. And, 4.32 (t, J ¼ 6.5 Hz, 4H, O–CH2), 4.12 (m, 4H, N–CH2), 2.04 (m,
the rst brown-black band should contain compounds 4 and 5, 4H, CH2), 1.92 (m, 2H, CH), 1.66 (m, 4H, CH2), 1.39 (m, 24H,
which are impossible to be separated by column chromatog- CH2), 0.97 (m, 12H, CH3), 0.90 (t, J ¼ 7.1 Hz, 6H, CH3); 13C NMR
ꢀ
raphy methods, but they could be separated by fractionating (400 MHz, CDCl3, 25 C): d ¼ 163.8, 163.5, 135.8, 133.4, 128.6,
precipitation procedure. The mixture of 4 and 5 was dissolved in 128.6, 128.3, 128.2, 125.5, 123.0, 122.8, 121.0, 70.5, 44.3, 38.0,
10 mL of THF, then 20 mL of CH3OH was added slowly. Aer the 31.6, 30.9, 29.4, 28.8, 26.1, 24.2, 23.1, 22.7, 14.1, 14.1, 10.7; MS
resulting mixtures were kept overnight, a brown precipitate (MALDI-TOF): m/z 815.6 (M++1); elemental analysis (%), calcd.
appeared. The brown precipitate was ltered with remaining a for (C52H66N2O6): C, 76.62; H, 8.16; N, 3.44; found: C, 76.89; H,
neat green ltrate solution. Then, CH3OH was added to the 8.25; N, 3.35.
green ltrate to give a green precipitate. These precipitation
Compound 8 (9 mg, 11%, calculation based on 3). UV/Vis
procedures were repeated by several times until the ltrate (CHCl3) lmax 574, 532, 503 nm; FT-IR (KBr, cmꢁ1) n 2958, 2869,
showed colorless. Finally, high purity compounds 4 and 5 were 2231 (s, –CN), 1695 (s, C]O), 1658 (s, C]O), 1593, 1437, 1330,
successfully isolated as the brown and green color solids.
1270; 1H NMR (400 MHz, CDCl3, 25 ꢀC): d ¼ 9.53 (d, J ¼ 8.1 Hz,
Compound 4 (35 mg, 3%, calculation based on 3). UV/Vis 1H, perylene-H), 8.81 (d, J ¼ 8.2 Hz, 1H, perylene-H), 8.52 (d, J ¼
(CHCl3) lmax 699, 677, 645, 612, 564, 520, 357 nm; FT-IR (KBr, 8.3 Hz, 1H, perylene-H), 8.43 (d, J ¼ 8.3 Hz, 1H, perylene-H),
cmꢁ1) n 2958, 2926, 2856, 1699 (s, C]O), 1661 (s, C]O), 1595, 8.18 (s, 1H, perylene-H), 8.06 (s, 1H, perylene-H), 7.05 (s, 1H, Ar-
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H), 6.94 (s, 1H, Ar-H), 4.36 (m, 2H, O–CH2), 4.03 (m, 2H, O–CH2),
3.88 (m, 2H, N–CH2), 3.71 (m, 2H, N–CH2), 2.05 (m, 2H, CH2),
1.91 (m, 3H, CH), 1.73 (m, 6H, CH2), 1.67–0.97 (m, 24H, CH2),
0.95–0.77 (m, 21H, CH3); MS (MALDI-TOF): m/z 985.4 (M++1);
elemental analysis (%), calcd. for (C62H72N4O7): C, 75.58; H,
7.37; N, 5.69; found: C, 75.39; H, 7.26; N, 5.75.
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Acknowledgements
This research was nancially supported by the Fundamental
Research Funds for the Central Universities (Beihang Univer-
sity, China).
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