Application of Near-IR Absorption Porphyrin Dyes Derived from Click Chemistry as Third-Order Nonlinear Optical Materials

Article abstract of DOI:10.1002/open.201500124

Recently, third-order nonlinear properties of porphyrins and porphyrin polymers and coordination compounds have been extensively studied in relation to their use in photomedicine and molecular photonics. A new functionalized porphyrin dye containing elect

Full text of DOI:10.1002/open.201500124

DOI: 10.1002/open.201500124
Application of Near-IR Absorption Porphyrin Dyes Derived
from Click Chemistry as Third-Order Nonlinear Optical
Materials
Yongsheng Mi,[a] Pengxia Liang,[a] Zhou Yang,*[a] Dong Wang,*[a] Hui Cao,[a] Wanli He,[a]
Huai Yang,*[b] and Lian Yu*[c]
Recently, third-order nonlinear properties of porphyrins and
porphyrin polymers and coordination compounds have been
extensively studied in relation to their use in photomedicine
and molecular photonics. A new functionalized porphyrin dye
containing electron-rich alkynes was synthesized and further
modified by formal [2+2] click reactions with click reagents
tetracyanoethylene (TCNE) and 7, 7, 8, 8-tetracyanoquinodime-
thane (TCNQ). The photophysical properties of these porphyrin
dyes, as well as the click reaction, were studied by UV/Vis spec-
troscopy. In particular, third-order nonlinear optical properties
of the dyes, which showed typical D-p-A structures, were char-
acterized by Z-scan techniques. In addition, the self-assembly
properties were investigated through the phase-exchange
method, and highly organized morphologies were observed by
scanning electron microscopy (SEM). The effects of the click
post-functionalization on the properties of the porphyrins
were studied, and these functionalized porphyrin dyes repre-
sent an interesting set of candidates for optoelectronic device
components.
Introduction
Materials with nonlinear optical (NLO) properties and fast re-
sponse to laser irradiation, as well those as with merits such as
small optical loss, high optical quality, good stability, low cost
and ease of preparation, have attracted increasing attention
owing to their potential applications in ultrafast optical switch-
ing, optical communication, optical modulators, and optical
limiting.[1–5] The chemist’s goal in this work is to design mole-
cules and materials with high nonlinear coefficients and devel-
op models that can predict these characteristics from the mo-
lecular structure.[6,7] Discovering organic molecules with large
nonlinear responses is an active pursuit, and properties are
often manipulated by making structural modifications to
donor and acceptor building blocks, as well as to conjugated
linking p-units.[8–10]
Porphyrins are comprised of four pyrrole units linked togeth-
er through their a-positions by methane bridges; the highly
delocalized aromatic 18p-electron system of porphyrins can
give rise to a strong NLO response.[11] Recently, third-order NLO
properties of porphyrins and porphyrin polymers and coordi-
nation compounds have been extensively studied in relation
to their use in photomedicine and molecular photonics.[12–18]
Although continuous optimization was explored previously,
some porphyrin derivatives were obtained through the fast,
high-yielding, and catalyst-free [2+2] click reaction,[19] However,
very little research has been done on the porphyrin dyes modi-
fied by [2+2] click chemistry with high third-order optical non-
linearities. In particular, innovative [2+2] cycloaddition of
strong electron acceptors, such as tetracyanoethene (TCNE)
and 7,7,8,8-tetracyanoquinodimethane (TCNQ), to electron-rich
alkynes provides efficient access to nonplanar push–pull chro-
mophores featuring intense intramolecular charge-transfer (CT)
and optical properties.[20–22]
[a] Y. Mi,+ P. Liang,+ Prof. Z. Yang, D. Wang, H. Cao, W. He
Department of Materials Science and Engineering
University of Science and Technology Beijing
30 Xueyuan Rd, Haidian, Beijing 100083 (P. R. China)
E-mail: yangz@ustb.edu.cn
wangdong@ustb.edu.cn
[b] Prof. H. Yang
Department of Materials Science and Engineering, Peking University
5 Yiheyuan Rd, Haidian, Beijing 100871 (P. R. China)
E-mail: yanghuai@pku.edu.cn
[c] Dr. L. Yu
State Key Laboratory of Coal Resource and Safe Mining
China University of Mining & Technology
11 Xueyuan Rd, Beijing, (P. R. China)
E-mail: yulian4228@126.com
[+] The authors Y. Mi and P. Liang have contributed equally to this article.
In this paper, we use click chemistry to aid the synthesis of
extraordinary porphyrin derivatives, which provides the por-
phyrin derivatives with a widened absorption spectra and im-
proved CT properties. These derivatives had D-p-A systems
that contain a middle acceptor and peripheral multi-donors in
contrast to the conventional linear type of D-p-A compounds,
and were prepared by quite short and high-yielding synthetic
routes. It is expected that the concept reported here can be
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/open.201500124.
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This is an open access article under the terms of the Creative Commons
Attribution-NonCommercial-NoDerivs License, which permits use and
distribution in any medium, provided the original work is properly cited,
the use is non-commercial and no modifications or adaptations are
made.
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expanded to other functional groups and may impact opto-
electronic applications in the future.
Moreover, the porphyrin derivatives were stable in the air at
room temperature, and could be dissolved in common organic
solvents such as dichloromethane, THF, and acetone, which
were beneficial for further processing.
Results and Discussion
Design and synthesis
Photophysical properties
A new ethynyl-bridged porphyrin intermediate (named PorÀ
ZnÀN) was designed and synthesized on the basis of Sonoga-
shira coupling reactions (Scheme 1). Hence, alkynylpyrene de-
rivative PorÀZnÀN, which consisted of porphyrin as acceptor,
N,N-didodecyl aniline as donor, and an ethynyl group as
a bridge, was firstly prepared as a click precursor. The alkoxy
groups were added in order to improve solubility and decrease
aggregations of the porphyrin derivatives. The products were
obtained in high yields, and these porphyrin derivatives have
good solubility in dichloromethane and tetrahydrofuran (THF).
Click chemistry provides efficient, reliable, and selective reac-
tions for synthesizing new compounds and generating combi-
natorial libraries. In particular, typically thermal [2+2] cycload-
ditions by reacting “electronically confused” alkynes with TCNE
and TCNQ are considered to be novel examples. These meso-
extended tetraarylporphyrin chromophores PYÀZnÀTCNE and
PYÀZnÀTCNQ were obtained through the high-yielding [2+2]
click reactions between alkynes and TCNE and TCNQ as shown
in Scheme 2. The structures and purities of newly prepared
The photophysical properties of organic materials are essential
parameters that provide important information on their con-
formations and electronic structures. The UV/Vis absorption
properties of PorÀZnÀN, PorÀZnÀTCNE, and PorÀZnÀTCNQ
were characterized by UV/Vis spectroscopy in dilute dichloro-
methane solutions at 298 K, as shown in Figure 1. The UV/Vis
spectra of these compounds exhibit features typical of a por-
phyrin ring, with an intense Soret band in the range 400–
500 nm and less intense Q bands in the range 600–1200 nm.
It is worth noting that the strongest absorption peaks of
both PorÀZnÀTCNE (433 nm) and PorÀZnÀTCNQ (453 nm)
showed an obvious blue-shift relative to PorÀZnÀN (474 nm),
which was attributed to the cyano group as strong acceptors
decrease the electronic cloud density of the porphine ring.[23]
Meanwhile, PorÀZnÀTCNQ is red shifted by 20 nm compared
1
products were confirmed by H NMR, Fourier-transform infra-
red (FT-IR), and mass spectrometry.
The reactions with the click reagent TCNE could be conduct-
ed under ambient temperature, and enhancement of tempera-
ture to 1008C was just for higher efficiency. However, the click
reactions of TCNQ required heating up to 1008C and holding
at reflux for 1 h to generate significantly high yields ranging
96%. Furthermore, in all click reactions, metal catalysts were
unnecessary, and purifications were done more easily in con-
trast with other reactions for the absence of by-products.
Figure 1. UV/Vis absorption spectra of PorÀZnÀN, PorÀZnÀTCNE, and
PorÀZnÀTCNQ in CH2Cl2 solutions.
Scheme 1. Molecular structures and synthetic routes of PorÀZnÀN. Reagents and conditions: a) trimethylsilylacetylene (TMSA), THF, Et3N, PdCl2(PPh3)2, CuI,
308C, 8 h, 13 %; b) K2CO3, MeOH, rt, 4 h, 93 %; c) 1) pyrrole, TFA, CH2Cl2, rt, 20 h, 2) Zn(OAc)2, 93 %; d) NBS, CH2Cl2, rt, 1 h, 82 %; e) Pd(PPh3)2Cl2, PPh3, CuI, THF,
Et3N, 808C, 12 h, 83 %.
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Scheme 2. Molecular structures and synthetic routes of the click reaction products.
with PorÀZnÀTCNE, resulting from the effective p-extended
conjugation caused by the hexatomic rings.
In comparison with PorÀZnÀN, both clicked products
showed end absorptions (lend) reaching into the near infrared
(900 nm for PorÀZnÀTCNE and 1200 nm for PorÀZnÀTCNQ)
which was ascribed to the electronic effect between the donor
(porphyrin) and acceptor (cyano group). Another fact worth
mentioning is that the lend of the products also showed obvi-
ously bathochromic shifts between PorÀZnÀTCNE and PorÀ
ZnÀTCNQ, concomitantly with increased conjugation lengths.
Time-resolved transient absorption spectra of porphyrins in
dichloromethane at room temperature were taken at various
delay times after the excitation pulse. The spectral trace of
PorÀZnÀN is shown in Figure 2, which displays broad negative
signals in the range of 400–500 nm and 630–700 nm, corre-
sponding to the bleaching of the strongly allowed S0!Sn ab-
sorption band upon excitation and also shows a buildup of
a strong transient absorption signals in the region of 500–
600 nm. The latter peak was associated with the S1!Sn transi-
Figure 2. Picosecond time-resolved transient spectra of compound
PorÀZnÀN excited at 532 nm.
creased with the increasing amount of the TCNE, finally lead-
ing to completely reddish-brown solutions. The presence of
the isosbestic points at 410, 451, and 512 nm for PorÀZnÀN
indicated no side reactions during the TCNE click reaction. The
tion.[24,25] Compared with PorÀZnÀN, the click products PorÀ position of the charge-transfer (CT) bands (at 437 nm) was ob-
ZnÀTCNE and PorÀZnÀTCNQ didn’t show any signals under
the same conditions, which were due to the increments of p-
conjugations and introduction of electron-withdrawing cyano
groups.
viously blue-shifted compared with the precursor PorÀZnÀN
(at 479 nm) during the experiments, suggesting that the elec-
tronic cloud density of porphyrin ring was decreased by the in-
troducing of strong electron-withdrawing groups (cyano
group). Porphyrin derivative PorÀZnÀN displayed a significant-
ly advantages that the products featured strong CT interac-
tions in the visible absorption-region-related properties. Fur-
thermore, the controlled introduction of these click products
Hereafter, the reaction of PorÀZnÀN was initially investigat-
ed by UV/Vis spectroscopic titration experiments by adding
the click reagent TCNE in chlorinated solvents. As shown in
Figure 3, Soret bands blue-shifted to 400–450 nm and in-
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and PorÀZnÀTCNE. Materials showing RSA became more
opaque on exposure to high photon fluxes due to the high ab-
sorption from the excited state, and this property has been ex-
ploited in the field of optical limiting for laser protection. How-
ever, Figure 4c shows a typical transmittance peak of com-
pound PorÀZnÀTCNQ, which exhibits saturable absorption
(SA)-type behavior. It could be observed that compared with
PorÀZnÀN and PorÀTCNE, PorÀZnÀTCNQ clearly exhibited
reverse saturable absorption–saturable absorption (RSA-SA)
transition by click reaction with TCNQ. The reason for conver-
sion from the RSA to SA phenomenon for PorÀZnÀTCNQ is
the threshold intensity[26] determined by the parameters such
as absorption cross section and level lifetime, and the satura-
tion intensity declined dramatically. Once the incident light in-
tensity crossed the threshold intensity, conversion from RSA to
SA happened.
From a plethora of recordings, the Imc(3) (the imagery parts
of the third-order nonlinearities) value of PorÀZnÀN was
found to be 1.0”10À11 esu, which corresponds to a nonlinear
absorption coefficient of b=4.8”10À10 mWÀ1. The Imc(3) values
of PorÀZnÀTCNE and PorÀZnÀTCNQ were 1.7”10À14 esu and
3.6”10À14 esu, while the nonlinear absorption coefficients b
were 7.9”10À13 mWÀ1 and À1.7”10À13, respectively. Compar-
ing to other organic molecules measured by Z-scan, the third-
order nonlinear values of our compounds were relatively
good.[27,28]
Figure 3. UV/Vis spectral changes of PorÀZnÀN upon titration with TCNE
(0–1.0 equiv) in dichlorobenzene at 208C.
into porphyrin was useful for optimization of the electronic
states, thereby leading to the enhanced performance of vari-
ous properties of optoelectronic materials. If the side-chain
chromophores did not interact with each other, the peak top
values should be constant. This result suggested that this click-
type reaction could affect the electronic states of the whole
conjugated compounds, and thus could be employed for
tuning the energy levels of the conjugated materials.
Nonlinear optical (NLO) properties
The NLO properties corresponding to PorÀZnÀN, PorÀZnÀ
TCNE, and PorÀZnÀTCNQ were measured by means of the Z-
scan technique, of which several recordings were acquired. All
of the samples were measured at 10À6 m solution in THF (spec-
tral pure, SP), and the solvent itself did not show any third-
order nonlinearities under the experimental conditions. The
nonlinear absorption coefficient b and the nonlinear reflective
index n2 would be available under measurements, and the
third-order nonlinear susceptibility could be calculated (de-
tailed calculation methods are listed in the Supporting Infor-
mation).
“Closed-aperture” Z-scan data of PorÀZnÀN, PorÀZnÀTCNE,
and PorÀZnÀTCNQ are shown in Figure 5. In this figure, the
Figure 4 shows the “open-aperture” Z-scan data and the nor-
malized transmittance curves of all products, which could be
fitted perfectly with respect to equations reported by referen-
ces.[19] In Figure 4a,b, profound transmittance valleys can be
seen around the focal plane, which was characteristic of re-
verse saturable absorption (RSA)-type behavior of PorÀZnÀN
Figure 5. Closed-aperture Z-scans measured in the THF solution of
PorÀZnÀN.
Figure 4. Open-aperture Z-scans measured in the THF solutions of a) PorÀZnÀN, b) PorÀZnÀTCNE, and c) PorÀZnÀTCNQ.
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normalized transmittance curve of PorÀZnÀN could be fitted
well according to the equation reported by reference and the
real part of third-order nonlinearity, Rec(3), was found to be
À1.1”10À11 esu, which corresponds to a nonlinear refractive
As the diagram shows, between Figure 6b and c, the morphol-
ogies could not be classified as pure J- or H-aggregates, but
their combination. In addition, due to the greater steric hin-
drance effect, the size of the self-assembled spheres of PorÀ
index n2 =À2.3”10À17 m2·wÀ1. However, click products PorÀ ZnÀTCNQ was smaller than that of PorÀZnÀTCNE. For most
ZnÀTCNE and PorÀZnÀTCNQ didn’t show closed-aperture
curves, and a plausible explanation could be that the nonlinear
absorption is much stronger than the refraction. The properties
of these products that we developed made it relatively impor-
tant for new molecule synthesis used in NLO applications.
materials, J-aggregates of organic dyes are of significant inter-
est for the development of advanced photonic technologies
for their abilities to delocalize and migrate excitonic energy
over a large number of aggregated dye molecules.[29]
Density functional theory (DFT) calculations
As shown in Figure 7, the DFT-optimized model structure of
compound PorÀZnÀN is close to planar. Both BP86 and TPSS
calculations yielded similar results. According to the TPSS/RI/
TZVP calculated results, the bond length of ZnÀN is about
2.053 Š, and the four bond angles of NÀZnÀN are 90.19. 89.88,
90.16, and 89.788; the sum of four NÀZnÀN angles is almost
3608 (360.018). Compared with the experimental results,[30] the
bond length of ZnÀN in compound ZnTPP is 2.045(2) Š, and
the four bond angles are about 90.16, 80.84, 90.16, and 80.848.
The DFT-calculated results agreed well with the experimental
data.
Self-assembly properties
To develop novel organic optoelectronic materials, the hier-
archical self-assembly of multivalent components through the
concerted action of multiple noncovalent interactions turns
out to be one of the most promising approaches, as it allows
the simultaneous organization of discrete molecules, long-
range order, and inherently defect-free structures. Taking this
into account, the introduction of an activated cyano group as
acceptor and metal ions into the discoid porphyrin core could
enhance multiple noncovalent interactions. The solvent-
exchanging method was used to form regular self-assembly
structures in the solution phase, and SEM images of self-
assembled morphologies are shown in Figure 6. A discoid-
distinct-like morphology shown in the Figure 6a was observed
for compound PorÀZnÀN because of the cooperation of the
p–p interactions and the metal ions coupling between the
layers (here mainly brickwork-type H-aggregates). The upper
right corner of Figure 6a is a schematic diagram of molecular
permutations of the discoid-distinct-like structure at the
micron scale. By introducing click reagents TCNE and TCNQ
substituents into the discoid cores, the degree of self-assem-
bling order of the compounds was likely to worsen due to the
increasing steric hindrance. Products PorÀZnÀTCNE and PorÀ
ZnÀTCNQ did not exhibit regular discoid-distinct-like morphol-
ogies; rather, spherical morphologies as shown in Figure 6b,c.
Figure 7. Optimized model structures obtained with DFT (TPSS/RI/TZVP)
calculations for compounds a) PorÀZnÀN, b) PorÀZnÀTCNE, and
c) PorÀZnÀTCNQ. Zn atoms: yellow, N atoms: blue, O atoms: red,
H atoms: white, C atoms: brown.
The DFT-optimized model structures of compounds PorÀ
ZnÀTCNE and PorÀZnÀTCNQ are both crooked (bent) due to
the large substituted groups introduced through click reac-
tions with TCNE or TCNQ. As a result of these bent structures,
spherical morphologies of compound PorÀZnÀTCNE and
PorÀZnÀTCNQ could be observed by SEM (Figure 6)
Conclusion
Figure 6. SEM images of self-assembled morphologies of compound a) PorÀ
ZnÀN, b) PorÀZnÀTCNE, and c) PorÀZnÀTCNQ; the yellow arrows are
pointing to the aggregation mode of different self-assembling morpholo-
gies.
In this work, a series of Zn-complexed D-p-A porphyrin deriva-
tives, PorÀZnÀN, PorÀZnÀTCNE, and PorÀZnÀTCNQ were de-
signed and synthesized through [2+2] click reactions based on
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The solvent was dried over anhydrous Na2SO4 and removed under
decreased pressure. The product was recrystallized from CH2Cl2/
MEOH to give a red solid PorÀC12ÀZn (0.93 mmol, 93%);1H NMR
(400 MHz, CDCl3): d=10.33 (s, 2H), 9.42 (d, 4H, J=6.4 Hz), 9.14 (d,
4H, J=6.4 Hz), 8.20 (d, 4H, J=8.0 Hz), 7.37 (d, 4H, J=6.4 Hz), 4.31
(t, 4H), 2.04 (m, 8H), 1.68 (m, 8H), 1.55 (m, 24H), 0.93 ppm (t, 6H);
FT-IR (KBr): v˜ =2920, 2859, 1449, 1474, 784 cmÀ1; MALDI-TOF-MS
(dithranol) m/z: calcd for C56H68N4O2Zn: 892.5, found: 892.3.
the aniline groups as donor units and cyano groups as accept-
or units. Investigations of the photophysical properties by
using UV/Vis spectroscopy showed that the charge-transfer
character of the D-p-A structures plays a key role in the ab-
sorption peak shifts, and the click products showed various
bathochromic shifts. Most importantly, upon the introduction
of electron acceptors by click reactions, the third-order nonlin-
ear absorption of the products showed typical RSA-SA transi-
tion, and both the products revealed relatively good third-
order nonlinear optical susceptibilities. In addition, the discoid-
distinct-like and spherical morphologies were observed
through a phase-exchange method for packing porphyrin mol-
ecules, and the results agreed well with DFT calculations. The
structure–property relationships of these porphyrin derivatives
were built and could help in promising applications in organic
electronics.
Synthesis of brominated porphyrin. To a solution of PorÀC12ÀZn
(1.00 mmol) in CH2Cl2 (100 mL) was added a solution of N-bromo-
succinimide (NBS, 712.0 mg, 4.00 mmol) in CH2Cl2 (10 mL). After
the mixture was stirred at rt for 1 h, the solvent was removed
under decreased pressure. The brown solid product BrÀPorÀC12
was purified by column chromatography (silica gel) using CH2Cl2/
hexane 1:1 as eluent (0.82 mmol, 82%);1H NMR (400 MHz, CDCl3):
d=9.42 (d, 4H, J=6.4 Hz), 9.12 (d, 4H, J=6.4 Hz), 8.22 (d, 4H, J=
8.0 Hz), 7.47 (d, 4H, J=6.4 Hz), 4.28 (t, 4H), 2.06 (m, 8H), 1.66 (m,
8H), 1.45 (m, 24H), 0.93 ppm (t, 6H); FT-IR (KBr): v˜ =2922, 2859,
1508, 1448, 1242 and 788 cmÀ1; MALDI-TOF-MS (dithranol) m/z:
calcd for C56H66Br2N4O2: 1048.3, found: 1048.2.
Experimental Section
Hagihara–Sonogashira cross-coupling procedure. Synthesis of
the PorÀZnÀN: Pd(PPh3)2Cl2 (17.0 mg, 0.0240 mmol), CuI (4.73 mg,
0.0240 mmol), and PPh3 (16.2 mg, 0.0600 mmol) were added to
a degassed solution of triethylamine (6 mL) and THF (10 mL) under
Ar. Meanwhile BrÀPorÀC12 (0.556 g, 0.600 mmol) was added. While
stirring, the reaction mixture was heated to 608C, and (4-ethynyl-
phenyl)-dioctyl-amine (1.64 g, 4.80 mmol) was injected to get PorÀ
ZnÀN. After 15 min of stirring at this temperature, the reaction
was heated to 808C and stirred o/n under Ar atmosphere. The
cooled reaction mixture was diluted with CH2Cl2 and extracted
with water. The organic phase was dried over MgSO4, and the sol-
vent was removed under decreased pressure. The crude product
was purified by column chromatography (silica gel, petroleum
ether) to afford the purple powder PorÀZnÀN (0.871 g, 83%);
1H NMR (400 MHz, CDCl3): d=9.00 (m, 8H), 8.11 (m, 8H), 7.29 (d,
4H, J=6.4 Hz), 7.22 (d, 4H, J=6.4 Hz), 4.28 (t, 4H), 3.36 (t, 8H),
2.01 (m, 16H), 1.65 (m, 16H), 1.52 (m, 32H), 1.40 (m, 36H) 1.34 (m,
32H), 0.94 ppm (m, 6H); FT-IR (KBr): v˜ =2934, 2182, 1668, 1522,
General conditions
Reagents were purchased from commercial sources (Aldrich) and
used without further purification. Triethylamine (TEA) and THF
were distilled and purged with Ar before use. TCNE and TCNQ
were purchased from Aldrich, and all other reagents were pur-
chased from commercial sources and used as received.
1H NMR spectra of the samples were recorded with a Varian
400 MHz instrument (Palo Alto, CA, USA) in CDCl3 using the residu-
al solvent resonance of CHCl3 at 7.26 ppm relative to SiMe4 as in-
ternal reference. FT-IR spectra were recorded in KBr pellets using
a PerkinElmer LR-64912C spectrophotometer (Waltham, MA, USA).
Matrix-assisted laser desorption ionization time-of-flight mass spec-
tra (MALDI-TOF-MS) were recorded on a Shimadzu AXIMA-CFR
mass spectrometer (Kyoto, Japan). All UV/Visible spectra were re-
corded on a HITACHI U-3010 spectrophotometer (Tokyo, Japan).
SEM images were obtained on a Jeol JSM-5400/LV (Tokyo, Japan)
with accelerating voltage of 15 kV.
1245, 822 cmÀ1
;
MALDI-TOF-MS (dithranol) m/z calcd for
C120H174N6O2Zn 1795.3, found 1795.7.
Synthesis
Synthesis of PorÀZnÀTCNE. Compound PorÀZnÀN (0.36 g,
0.20 mmol, 1 equiv) and TCNE (51.2 mg, 0.40 mmol, 2 equiv) were
mixed in CH2Cl2 (10 mL). After stirring for 10 min, the solvent was
removed under decreased pressure, and the crude product was
purified by column chromatography (silica gel, ethyl acetate/petro-
leum ether 1:4) to give the final click-type reaction product PorÀ
ZnÀTCNE as a dark green solid (0.36 g, 89%); 1H NMR (400 MHz,
CDCl3): d=7.52 (12H, d, J=8.0 Hz), 7.27 (2H, d, J=8.0 Hz), 7.20
(4H, d, J=8.0 Hz), 6.94 (4H, d, J=8.0 Hz), 6.71 (4H, d, J=8.0 Hz),
6.68 (2H, d, J=8.0 Hz), 6.77 (2H, d, J=8.0 Hz), 6.44 (2H, d, J=
8.0 Hz), 5.39 (2H, d, J=8.0 Hz), 4.06 (4H, m), 3.78 (8H, m), 1.76–
1.26 (120H, m), 0.88 ppm (18H, m); FT-IR (KBr): v˜ =2923, 2863,
2220, 1738, 1596, 1285, 1184 cmÀ1; MALDI-TOF-MS (dithranol) m/z:
calcd for C132H174N14O2Zn: 2051.3, found: 2049.6.
Synthesis of PorÀC12ÀZn: To a degassed solution of dipyrrome-
thane
(146.0 mg,
1.00 mmol),
4-dodecyloxy-benzaldehyde
(290.2 mg, 1.00 mmol) in CH2Cl2 (100 mL) was added trifluoroacetic
acid (TFA, 0.60 mmol, 44 mL). The mixture was stirred in the dark
for 3 h, and then 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ,
0.90 mmol, 200.0 mg) was added. Afterwards, the solution was
stirred at rt for another 1 h, and the solvent was removed under
decreased pressure. The product was isolated by column chroma-
tography (silica gel) using CH2Cl2/hexane 1:1 as eluent. Recrystaliza-
tion from CH2Cl2/MeOH gave a red solid, PorÀC12, (0.065 mmol,
1
13%); H NMR (400 MHz, CDCl3): d=10.33 (s, 2H), 9.42 (d, 4H, J=
6.4 Hz), 9.15 (d, 4H, J=6.4 Hz), 8.20 (d, 4H, J=8.0 Hz), 7.36 (d, 4H,
J=6.4 Hz), 7.29 (s, 2H,), 4.30 (t, 4H), 2.05 (m, 8H), 1.51 (m, 30H),
0.92 ppm (t, 6H); FT-IR (KBr): v˜ =2920, 2859, 1448, 1474, 1242,
784 cmÀ1; MALDI-TOF-MS (dithranol) m/z: calcd for C56H70N4O2:
830.5, found: 830.7.
Synthesis of PorÀZnÀTCNQ. Compound PorÀZnÀN (0.36 g,
0.20 mmol, 1 equiv) and TCNQ (0.08 g, 0.40 mmol, 2 equiv) were
dissolved in dichlorobenzene (10 mL). Under stirring, the reactor
was heated to 1408C and maintained for 1 h. The solvent of the
cooled reaction mixture was removed under decreased pressure,
and the crude product was purified by column chromatography
(silica gel, ethyl acetate/petroleum ether=1/4) to give the pure
To a solution of PorÀC12 (1.00 mmol) in CH2Cl2 (50 mL) was added
a solution of Zn(OAc)2 (283.0 mg, 1.29 mmol) in MeOH (10 mL).
After the mixture was stirred at rt for 1 h, the solvent was removed
under decreased pressure. The residue was extracted with CH2Cl2.
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PorÀZnÀTCNQ as a black solid (0.38 g, 87%); 1H NMR (400 MHz,
CDCl3): d=7.52 (12H, d, J=8.0 Hz), 7.27 (2H, d, J=8.0 Hz), 7.20
(4H, d, J=8.0 Hz), 6.94 (4H, d, J=8.0 Hz), 6.71 (4H, d, J=8.0 Hz),
6.68 (2H, d, J=8.0 Hz), 6.77 (2H, d, J=8.0 Hz), 6.44 (2H, d, J=
8.0 Hz), 5.84 (8H, d, J=8.0 Hz)5.39 (2H, d, J=8.0 Hz), 4.06 (4H, m),
3.78 (8H, m), 1.76–1.26 (120H, m), 0.88 ppm (18H, m); FT-IR (KBr):
v˜ =2922, 2864, 2219, 1739, 1594, 1285, 1184, 980 cmÀ1; MALDI-
TOF-MS (dithranol) m/z: calcd for C144H182N14O2Zn: 2203.4, found:
2202.8.
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Keywords: Click reactions
porphyrin derivatives · self-assembly · third-order nonlinear
optical properties
·
near-infrared absorption
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Received: May 11, 2015
Revised: September 11, 2015
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