Synthesis, crystal structure, spectral and thermodynamic properties of one benzoindole pentamethine cyanine dye

Article abstract of DOI:10.1002/jccs.201200405

One benzoindole pentamethine cyanine dye was synthesized and characterized by ¹H NMR, IR, MS and UV-Vis spectra. The UV-Vis absorption and fluorescence spectra of the dye in chloroform, dimethyl sulfoxide, acetone, ethanol and methanol were investigated, and the λ_max of the dye was in the region 682.0-689.0 nmwith large molar extinction coefficients (ε > 10⁵M^-1cm^-1) in different solvents. The structure of the dye was also characterized and analyzed by X-ray diffraction. Crystallographic data revealed that the dye belonged to orthorhombic, with space group P212121, a = 10.059(2) A, b = 15.098(4) A, c = 24.989(6) A, V = 3794.8(15) A3, Z = 4. TheC-H·F intermolecular hydrogen bonds were displayed in the molecular system, which were effective in the molecular packing. The aggregation behavior and thermodynamic properties of the dye in aqueous methanol solution were also studied by means of UV-Vis spectroscopy methods. The results indicated that the dye existed monomer-dimer equilibrium in aqueous methanol solutions. The fundamental properties of the dye, such as the dimeric association constant KD, the dimeric free energy ΔGD, the dimeric entropy ΔSD, and the dimeric enthalpy ΔHD were determined. The ΔHD of the dye was -46.0 kJ mol ^-1.

Full text of DOI:10.1002/jccs.201200405

JOURNAL OF THE CHINESE
CHEMICAL SOCIETY
Article
Synthesis, Crystal Structure, Spectral and Thermodynamic Properties of One
Benzoindole Pentamethine Cyanine Dye
a
a
b
a
a
Xiu-Fu Zhang, Jun-Long Zhao, Wei-Bin Bi, Dan-Dan Zhang, Zhi-Yuan Yang and
a,
Lan-Ying Wang *
Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Ministry of Education, College of Chemistry
a
and Materials Science, Northwest University, Xi’an 710069, P. R. China
b
Institute of Condensed Matter Physics & Materials, Northwest University, Xi’an 710069, P. R. China
(Received: Jul. 21, 2012; Accepted: Nov. 16, 2012; Published Online: Feb. 11, 2013; DOI: 10.1002/jccs.201200405)
1
One benzoindole pentamethine cyanine dye was synthesized and characterized by H NMR, IR, MS and
UV-Vis spectra. The UV-Vis absorption and fluorescence spectra of the dye in chloroform, dimethyl
sulfoxide, acetone, ethanol and methanol were investigated, and the lmax of the dye was in the region
5
-1
-1
6
82.0–689.0 nm with large molar extinction coefficients (e > 10 M cm ) in different solvents. The struc-
ture of the dye was also characterized and analyzed by X-ray diffraction. Crystallographic data revealed
that the dye belonged to orthorhombic, with space group P2
1
2
1
2
1
, a = 10.059(2) Å, b = 15.098(4) Å, c =
3
¼
2
4.989(6) Å, V = 3794.8(15) Å , Z = 4. The C-H F intermolecular hydrogen bonds were displayed in the
molecular system, which were effective in the molecular packing. The aggregation behavior and thermo-
dynamic properties of the dye in aqueous methanol solution were also studied by means of UV-Vis spec-
troscopy methods. The results indicated that the dye existed monomer-dimer equilibrium in aqueous
methanol solutions. The fundamental properties of the dye, such as the dimeric association constant K
the dimeric free energy DG , the dimeric entropy DS , and the dimeric enthalpy DH were determined.
The DH of the dye was –46.0 kJ mol .
D
,
D
D
D
-
1
D
Keywords: Benzoindole; Pentamethine cyanine dye; Crystal structure; Spectral properties; Ther-
modynamic properties.
INTRODUCTION
Benzoindole pentamethine cyanine dyes have been
extensively applied in the fields of biomacromolecule fluo-
important role in many fields of applied chemistry such as
biomedical field, photographic chemistry, laser chemis-
1
0-12
try,
etc. Therefore, the study on the crystal structure,
1
-3
4
rescent labeling, nonlinear optical materials and optical
spectral properties and aggregation behavior of cyanine
dyes has guiding function on their practical application.
Our previous efforts have been devoted to developing
5
-6
disc storage, due to their stability and excellent spectral
properties, including large molar extinction coefficients,
broad wavelength tunability, and particularly their high
near-infrared (NIR) absorption and emission wavelengths.
Whether cyanine dyes will be widely used depends
on its structure and some properties, such as spectroscopic
properties, the aggregation behavior of dyes in solution etc.
The X-ray single crystal structure of cyanine dyes can pro-
vide details of the molecular conformation, including the
intra- and inter-molecular interactions in the solid state,
and the information which assists to understand the techni-
1
3-16
the synthesis and applications of cyanine dyes.
There
are many literatures on the synthesis and applications of
1
7-18
benzoindole pentamethine cyanine dyes.
However, the
X-ray single crystal structure, the aggregation behavior of
benzoindole pentamethine cyanine dyes in aqueous media
and their thermodynamic characteristics have seldom been
reported.
In this paper, one benzoindole pentamethine cyanine
dye was synthesized (Scheme I). And its X-ray single crys-
tal structure, spectral properties in different solvents and
aggregation behavior in aqueous methanol solution were
investigated. The research aims at obtaining theoretical ba-
sis and accumulating experimental data for its practical ap-
plication.
7
-9
cal performance of the dyes. Aggregation is one of the
features of cyanine dyes in solution, affecting their photo-
physical and photochemical properties. Many photophysi-
cal processes and photochemical reactions of cyanine dyes
involve associated molecules, and the aggregation plays an
*
Corresponding author. Tel: +86 29 88302604; Fax: +86 29 88303798; E-mail: wanglany@nwu.edu.cn
J. Chin. Chem. Soc. 2013, 60, 503-510
© 2013 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
503

Article
Zhang et al.
Scheme I Synthetic route of dye 5
mmol) and 2,3,3-trimethyl-3H-benz[e]indole (4.60 g, 22 mmol)
was heated at 120 °C for 4 h, then butyl alcohol was added,
refluxing for several hours. After cooling, the product was filtered
off and washed with butyl alcohol, a gray solid was obtained (7.66
g, yield 79.7%, m.p.: 169–170 °C).
NH2
Cl
H
Cl
H
OH C2H5OH
N
N
2
+
O
HCl
Cl
O
1
n-C4H9OH
N
Preparation of 1-Butyl-2,3,3-trimethyl-3H-benz[e]in-
dolium hexafluorophosphate (4)
N
H3C
SO2Cl
H3C
SO3C4H9
n
H3C
SO3
2
3
The aqueous solution (1%) of 1-butyl-2,3,3-trimethyl-3H-
benz[e]indolium 4-methylbenzenesulfonate 3 (0.68 g, 1.54
Cl
H
N
N
HCl
KPF6
mmol) and KPF
(0.28 g, 1.54 mmol) was prepared respectively.
aqueous so-
6
N
PF6
N
N
(
CH3CO)2O / CH3COONa
Cl
PF6
Then the aqueous solution of 3 was added to the KPF
6
lution slowly and stirred at room temperature for several hours,
and the resulting precipitate was filtered off and was used directly
for the next step without further purification.
4
5
EXPERIMENTAL
General
Preparation of dye (5)
1
-Butyl-2,3,3-trimethyl-3H-benz[e]indolium hexafluoro-
phosphate 4 (2.24 g, 5.45 mmol) and N-(2-chloro-3-phenylimino-
-propenyl)aniline hydrochloride 1 (0.80 g, 2.71 mmol) were dis-
All reagents were obtained from commercial sources and
used without further purification. The solvents were of analytical
grade. Melting points were taken on an XT-4 micromelting appa-
ratus and uncorrected. IR spectra were recorded on a Brucker
1
solved in acetic anhydride (6 mL) under heating conditions, and
anhydrous sodium acetate was added. The resulting mixture was
refluxed for 3 h. After cooling, the product was filtered off and
purified by recrystallization from methanol. A red powder with
metallic luster was obtained (1.44 g, yield 71.2%). m.p.: 248–249
1
Equinox-55 spectrometer. H NMR spectra were recorded at 400
MHz on a Varian Inova-400 spectrometer and chemical shifts
4
were reported relative to internal Me Si. MS was recorded on a
5
-1
-1
HP5973 MS spectrometer. The UV-vis absorption spectra were
recorded on a Shimadzu UV-1700 UV-vis spectrometer. The fluo-
rescence emission spectra were recorded on a Hitachi F-4500
spectrofluorimeter. The X-ray diffraction data were collected on a
Bruker SMART APEX II CCD X-ray diffractometer.
°
C. UV-Vis (MeOH) lmax: 682 nm. e: 2.12 × 10 M cm ; IR
(
KBr) u: 3030 (w, u=CH), 2932 (w, uC-H), 1625 (m, uC=C), 1483 (s,
u
C=C, uC=N), 1354, 1285, 1236, 1163, 1102, (s, uC-N, d=CH), 926,
1
8
30 (s, d=CH), 734 (uC-Cl); H NMR (DMSO-d
6
, 400 MHz) d
), 1.42–1.47 (m, 4H, 2CH ),
), 2.01 (s, 12H, 2C(CH ), 4.34 (t, 4H, J
(
ppm): 0.98 (t, 6H, J = 7.4 Hz, 2CH
3
2
Preparation of N-(2-chloro-3-phenylimino-1-pro-
penyl)aniline hydrochloride (1)
1
.78–1.83 (m, 4H, 2CH
2
3 2
)
= 7.4 Hz, 2NCH ), 6.42 (d, 2H, J = 13.6 Hz, 2-CH=), 7.57 (t, 2H,
2
Mucochloric acid (6.00 g, 36 mmol) was dissolved in etha-
nol (16 mL), and a solution of aniline (6.70 g, 72 mmol) in 24 mL
alcohol was rapidly added. The mixture was refluxed for 30 min.
After cooling, the product was filtered off and purified by recrys-
tallization from ethanol to give a orange solid (9.16 g, 86.5%),
J = 7.4 Hz, ArH), 7.72 (t, 2H, J = 7.8 Hz, ArH), 7.85 (d, 4H, J =
9.2 Hz, ArH), 8.12 (2dd, 4H, J = 8.8 Hz, J = 7.6 Hz, ArH), 8.29
1
2
(d, 2H, J = 8.8 Hz, ArH), 8.62 (d, 2H, J = 13.6 Hz, 2CH=CCl); MS
(70 eV) m/z (%): 566 (41), 534 (10), 509 (4), 315 (12), 286 (10),
251 (100), 208 (78), 165 (20), 152 (15), 107 (9), 57 (10), 43 (15),
18 (4).
1
9
m.p.: 228-229 °C (lit, m.p.: 228 °C).
Preparation of n-Butyl p-toluenesulfonate (2)
The 4-toluenesulfonyl chloride (20.00 g, 100 mmol) and
butyl alcohol (20.00 g, 270 mmol) were mixed, and 6.80 g of 25%
NaOH was added dropwise at 23-27 °C for 4 h. The mixture was
placed for several hours and the ester layer was washed with wa-
ter, 5% of sodium carbonate solution, water in turn. Crude prod-
uct was obtained and was used directly for the next step without
further purification.
Determination of the spectral properties
-
3
-1
The stock solution (1 × 10 mo1 L in dimethyl sulfoxide
(DMSO)) of dye 5 was diluted with different solvents to a suitable
volume in order to obtain the required concentration. The UV-Vis
absorption spectra in different solvents were examined at room
temperature and recorded using 1 cm quartz cells on a Shimadzu
UV-1700 UV-Vis spectrometer. Fluorescence measurements were
carried out at room temperature on a Hitachi F-4500 spectro-
fluorimeter in 1 cm quartz cells.
Preparation of 1-Butyl-2,3,3-trimethyl-3H-benz[e]in-
dolium-4-methylbenzenesulfonate (3)
The corresponding fluorescence quantum yields were cal-
culated relative to a standard solution of Rhodamine B in ethanol
A mixture of n-butyl p-toluenesulfonate 2 (5.02 g, 22
504
www.jccs.wiley-vch.de
© 2013 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
J. Chin. Chem. Soc. 2013, 60, 503-510

JOURNAL OF THE CHINESE
CHEMICAL SOCIETY
Synthesis, Crystal and Properties of One Cyanine Dye
Table 1. Photophysical characteristics of dye 5 in different solvents
-
5
Stokes Shifts
nm
e × 10
Dye
Solvent
lmax/nm
l /nm
em
-1
-1
F
/
/M cm
methanol
ethanol
DMSO
chloroform
acetone
682.0
686.0
688.0
689.0
682.0
705.2
707.0
710.0
709.0
706.0
23.2
21.0
22.0
20.0
24.0
2.12
2.08
1.82
2.17
2.14
0.011
0.013
0.018
0.034
0.012
5
2
0
(
F = 0.56) and were determined using the following formula:
fluorophosphate and N-(2-chloro-3-phenylimino-1-pro-
penyl)aniline hydrochloride could react easily using acetic
anhydride as solvent and sodium acetate as catalyst when
refluxing. The product was collected and recrystallized
from methanol with high yield.
2
x s x s x s s x x s
F = F (F /F ) (A /A ) (lex /lex ) (n /n )
where F is quantum yield, F is integrated area under the
corrected emission spectrum, A is absorbance at the excita-
tion wavelength, lex is the excitation wavelength, n is the
refractive index of the solution used in measurement and
the subscripts x and s denote test and the standard, respec-
tively.
The spectral properties of dye 5 in different solvents
The photophysical characteristics of dye 5 in differ-
ent solvents are shown in Table 1. As indicated in the table,
the lmax of the dye was in the region 682.0–689.0 nm and
the fluorescence maxima were located at 705.2–710.0 nm
in different solvents. The dye exhibited strong absorption
in near-infrared (NIR) region with large molar extinction
coefficients (e) in solutions, which were in the range of
Crystallography
Crystals suitable for X-ray analysis of dye 5 were obtained
by diffusion from methanol and water. All the measurements were
made on a Bruker SMART APEX II CCD diffractometer equipped
with a graphite monochromated Mo Ka radiation (l = 0.71073 Å)
by using w scan technique at room temperature. The structure
5
5
-1
-1
1
.82 × 10 to 2.17 × 10 M cm , and the fluorescence
quantum yield was in the range of 0.011 to 0.034 in differ-
ent solvents. Fig. 1. shows the absorption spectra of dye 5
in different solvents. It could be also found that the peak
profile of the dye was basically similar in different sol-
vents, and there were two absorption peak, located at 682–
2
1
were solved by direct methods with SHELXL-97, and refined
2
using the full-matrix least-squares procedures on F with aniso-
tropic thermal parameters for all non-hydrogen atoms using
2
2
SHELXL-97. Hydrogen atoms were generated geometrically.
Crystallographic data for the structure of dye 5 have been
deposited with the Cambridge Crystallographic Data Centre as
supplemental publication nos, CCDC 826102. Copies of the data
can be obtained, free of charge, on application to CCDC, 12 Un-
ion Road, Cambridge CB2 1EZ, UK (fax: +44-1223-336033 or
e-mail: deposit@ccdc. cam.ac.uk).
6
89 nm and 634–638 nm, respectively. This suggested that
the dye existed the monomer form (M) and aggregation
form (H) in different solvents.
Crystal structure analysis
The crystal structure of dye 5 is shown in Fig. 2. The
Determination of the aggregation behavior and ther-
modynamic properties
-
4
-1
The stock solution (1 × 10 mol L ) was prepared by dis-
solving dye 5 in methanol. All working solutions were diluted
with 50 volume % aqueous methanol solutions to a suitable vol-
ume in order to obtain the required concentration. The UV-Vis ab-
sorption spectra were examined and recorded using 1 cm quartz
cells on a Shimadzu UV-1700 UV-Vis spectrometer.
RESULTS AND DISCUSSION
Synthesis
Fig. 1. Absorption spectra of dye 5 in different sol-
1
-Butyl-2,3,3-trimethyl-3H-benz[e]indolium hexa-
vents.
J. Chin. Chem. Soc. 2013, 60, 503-510
© 2013 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.jccs.wiley-vch.de
505

Article
Zhang et al.
crystal data, details concerning data collection and struc-
ture refinement for dye 5 are summarized in Table 2. Some
selected bond lengths, bond angles and torsion angles for
the dye molecule are recorded in Table 3, Table 4 and Table
Table 2. Crystal data and structure refinement for dye 5
Empirical formula
C H ClF N P
41 46 6 2
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
space group
a/Å
b/Å
c/Å
a/(°)
747.22
296(2)
0.71073
5
, respectively.
As seen in Table 3–5, the observed carbon-carbon
Orthorhombic
P2 2 2
1
1 1
bond lengths in the framework molecule are almost inter-
mediate between typical C-C single bond (1.54 Å) and
C=C double bond (1.34 Å), similarly, the carbon-nitrogen
bond lengths of the framework molecule are also interme-
diate between C-N single bond (1.47 Å) and C=N double
bond (1.27 Å). This means that the bond length of the car-
bon-carbon bond and the carbon-nitrogen bond in the
framework molecule has a tendency of averages, the p or-
bits have overlapped and crossed-cover, and the p electrons
in the whole dye molecule are delocalized. All C-C-C,
C-N-C and C-C-N bond angles are close to 108° in five-
membered ring, and all C-C-C, C-N-C and C-C-N bond an-
gles are close to 120° in six-membered ring and methine
chain. In the framework molecule, 16 atoms [C(1), C(2),
C(3), C(4), C(5), C(6), C(7), C(8), C(9), C(10), C(11),
C(14), N(1), C(15), C(16), C(17)] have good coplanarity,
and the other 16 atoms [C(17), C(18), C(19), C(20), C(21),
C(24), C(25), C(26), C(27), C(28), C(29), C(30), C(31),
C(32), C(33), N(2)] have good coplanarity, too. The torsion
angles of C(15)-C(16)-C(17)-C(18) and C(16)-C(17)-
C(18)-C(19) [168.9(10)° and –170.4(10)°, respectively]
show that the two planes in the framework molecule are
slightly distorted each other.
10.059(2)
15.098(4)
24.989(6)
90
b/(°)
90
g/(°)
Volume (Å )
Z
Calculated density (Mg/m )
Absorption coefficient (mm ) 0.204
90
3
3794.8(15)
4
1.308
3
-1
F(000)
Crystal size (mm )
q Range for data collection
Limiting indices h, k, l
Refinement method
1568
0.36 × 0.26 × 0.13
1.58-25.05
-11 < 11, -16 < 17, -22 < 29
Full-matrix least-squares on F
0.979
3
2
2
Goodness-of-fit on F
Final R indices [I > 2s(I)]
R = 0.1000, wR = 0.1788
1 2
R indices (all data)
R = 0.2416, wR = 0.2431
1 2
Table 3. Some selected bond lengths (Å ) for dye 5
Cl(1)-C(17)
N(1)-C(14)
N(1)-C(1)
N(1)-C(38)
N(2)-C(20)
N(2)-C(33)
N(2)-C(34)
C(1)-C(10)
C(1)-C(2)
C(2)-C(3)
C(3)-C(4)
C(4)-C(5)
C(4)-C(9)
C(5)-C(6)
C(6)-C(7)
C(7)-C(8)
C(8)-C(9)
C(9)-C(10)
C(10)-C(11)
C(11)-C(14)
1.750(9)
C(14)-C(15)
C(15)-C(16)
C(16)-C(17)
C(17)-C(18)
C(18)-C(19)
C(19)-C(20)
C(20)-C(21)
C(21)-C(24)
C(24)-C(33)
C(24)-C(25)
C(25)-C(26)
C(25)-C(30)
C(26)-C(27)
C(27)-C(28)
C(28)-C(29)
C(29)-C(30)
C(30)-C(31)
C(31)-C(32)
C(32)-C(33)
1.367(12)
1.404(11)
1.378(11)
1.387(11)
1.382(11)
1.374(11)
1.526(12)
1.489(12)
1.356(13)
1.396(12)
1.421(13)
1.430(13)
1.354(12)
1.433(15)
1.357(15)
1.432(12)
1.432(14)
1.331(12)
1.425(12)
1.348(10)
1.379(11)
1.491(11)
1.304(11)
1.402(11)
1.501(11)
1.336(11)
1.444(11)
1.320(12)
1.402(12)
1.385(13)
1.427(12)
1.338(13)
1.401(13)
1.320(13)
1.453(12)
1.390(12)
1.530(12)
1.530(12)
1 1 1
Dye 5 crystallizes in the P2 2 2 space group with
four dye molecules per unit cell. As can be seen from the
packing diagrams of the dye viewed down the b-axis (Fig.
), the dye molecules form a layer structure in the bc plane
3
with slight distorted, and stack to form a column along the
a-axis direction. In the column, adjacent molecules are ar-
ranged due to the intermolecular hydrogen bonds (Table 6),
Fig. 2. The crystal structure of dye 5.
506
www.jccs.wiley-vch.de
© 2013 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
J. Chin. Chem. Soc. 2013, 60, 503-510

JOURNAL OF THE CHINESE
CHEMICAL SOCIETY
Synthesis, Crystal and Properties of One Cyanine Dye
Table 4. Some selected bond angles (°) for dye 5
gate and monomer.
Table 7 lists the absorbency of dye 5 at lmax of differ-
ent temperatures and concentrations. It can be found that
the absorption of dye 5 at the same concentration is de-
creased with an increase of temperature, but the range of
change is not great.
C(14)-N(1)-C(1)
C(20)-N(2)-C(33) 111.1(8) C(18)-C(17)-Cl(1) 116.3(7)
112.4(7) C(16)-C(17)-Cl(1) 118.5(8)
C(10)-C(1)-N(1)
C(10)-C(1)-C(2)
N(1)-C(1)-C(2)
C(3)-C(2)-C(1)
C(2)-C(3)-C(4)
C(5)-C(4)-C(3)
C(5)-C(4)-C(9)
C(3)-C(4)-C(9)
C(6)-C(5)-C(4)
C(5)-C(6)-C(7)
C(8)-C(7)-C(6)
C(7)-C(8)-C(9)
C(10)-C(9)-C(4)
C(10)-C(9)-C(8)
C(4)-C(9)-C(8)
C(1)-C(10)-C(9)
111.9(8) C(19)-C(18)-C(17) 128.7(9)
121.3(9) C(20)-C(19)-C(18) 130.1(9)
126.7(9) N(2)-C(20)-C(19) 123.3(9)
117.4(9) N(2)-C(20)-C(21) 109.0(8)
123.0(10) C(19)-C(20)-C(21) 127.7(9)
122.3(10) C(24)-C(21)-C(20) 101.5(8)
118.8(9) C(33)-C(24)-C(25) 120.1(9)
118.9(9) C(33)-C(24)-C(21) 108.5(8)
123.3(11) C(25)-C(24)-C(21) 131.4(9)
118.9(10) C(24)-C(25)-C(26) 125.9(10)
121.5(11) C(24)-C(25)-C(30) 118.7(9)
121.3(10) C(26)-C(25)-C(30) 115.4(10)
117.6(9) C(27)-C(26)-C(25) 123.3(11)
126.1(9) C(26)-C(27)-C(28) 119.3(12)
116.2(9) C(29)-C(28)-C(27) 121.5(11)
121.5(9) C(28)-C(29)-C(30) 118.1(12)
Fig. 4. shows absorption spectra of dye 5 at different
concentrations in 50 volume % aqueous methanol solutions
at 20.0 °C. As shown, there are two absorption peaks in vis-
ible range in 50 volume % aqueous methanol solutions.
The peaks at 682 and 634 nm can be assigned to monomer
(
M) band and aggregation (H) band, respectively. The ab-
sorption intensity of aggregation (H) and monomer (M)
band increases with increasing dye concentration. It can be
also found that the absorption wavelength of dye 5 with the
same concentration at different temperatures is same (Fig.
C(1)-C(10)-C(11) 106.9(9) C(25)-C(30)-C(29) 122.3(12)
C(9)-C(10)-C(11) 131.6(8) C(25)-C(30)-C(31) 118.3(10)
C(14)-C(11)-C(10) 102.8(7) C(29)-C(30)-C(31) 119.3(12)
N(1)-C(14)-C(15) 123.5(9) C(32)-C(31)-C(30) 122.1(10)
N(1)-C(14)-C(11) 106.1(8) C(31)-C(32)-C(33) 118.2(10)
C(15)-C(14)-C(11) 130.5(9) C(24)-C(33)-N(2) 109.9(9)
C(14)-C(15)-C(16) 127.0(9) C(24)-C(33)-C(32) 122.5(10)
C(17)-C(16)-C(15) 124.8(9) N(2)-C(33)-C(32) 127.6(10)
C(16)-C(17)-C(18) 125.2(9)
5
.). The results show that dye 5 may exist an equilibrium
between monomer and dimer which is also observed in the
crystal structure, in 50 volume % aqueous methanol solu-
2
3
tions between 20.0 °C to 40.0 °C. That is, the main peak at
which are effective in the molecular packing. Specifically,
the F2 and F5 of one hexafluorophosphate anions interact
with the two adjacent molecules via C2-H2¼F5 and C36-
H36B¼F2 hydrogen bonds, respectively. It can be also
found that in the crystal structure there are two types of the
column, which is arranged by parallel and face-to-face dye
molecules respectively, and the adjacent dye molecules
form aggregate by means of the intermolecular hydrogen
bonds. As a result, the extension of the dye molecules
Fig. 3. The diagram of crystal packing of dye 5: along
b axis.
forms a three-dimensional framework, and the C-H¼
F
intermolecular hydrogen bonds generate a unique supra-
molecular architecture in the solid state of the dye.
Aggregation behavior and thermodynamic properties
analysis
The aggregation of cyanine dyes in solution is a com-
mon phenomenon. The formation of molecular aggregation
state is generally influenced and controlled by many fac-
tors, among which the structure of dye molecule, tempera-
ture and concentration are important. There are several dif-
ferent types of aggregates in solution of cyanine dye, and
there is a dynamic reversible equilibrium between aggre-
Fig. 4. Absorption spectra of dye 5 at different concen-
trations and 20.0 °C in 50 volume % aqueous
-
6
-1
methanol solutions. a: 2.45 × 10 mol·L , b:
-6
-1
-6
-1
3
.66 × 10 mol·L , c: 4.88 × 10 mol·L , d:
-
6
-1
-6
-1
5.70 × 10 mol·L , e: 6.10 × 10 mol·L .
J. Chin. Chem. Soc. 2013, 60, 503-510
© 2013 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.jccs.wiley-vch.de
507

Article
Zhang et al.
Table 5. Some selected torsion angles (°) for dye 5
C(14)-N(1)-C(1)-C(10)
C(14)-N(1)-C(1)-C(2)
N(1)-C(1)-C(2)-C(3)
-1.8(11)
-178.2(9)
-178.1(9)
179.8(8)
1.8(10)
-1.1(9)
-178.5(8)
0.9(10)
C(16)-C(17)-C(18)-C(19)
Cl(1)-C(17)-C(18)-C(19)
C(17)-C(18)-C(19)-C(20)
C(33)-N(2)-C(20)-C(21)
C(18)-C(19)-C(20)-N(2)
C(18)-C(19)-C(20)-C(21)
N(2)-C(20)-C(21)-C(24)
C(19)-C(20)-C(21)-C(24)
C(20)-C(21)-C(24)-C(33)
C(25)-C(24)-C(33)-N(2)
C(21)-C(24)-C(33)-N(2)
C(20)-N(2)-C(33)-C(24)
C(20)-N(2)-C(33)-C(32)
C(31)-C(32)-C(33)-N(2)
-170.4(10)
5.8(15)
178.5(10)
2.9(11)
-175.1(10)
7.7(17)
-2.4(10)
175.1(9)
1.0(10)
179.6(8)
0.6(11)
-2.3(12)
178.8(9)
-179.5(9)
N(1)-C(1)-C(10)-C(9)
N(1)-C(1)-C(10)-C(11)
C(1)-C(10)-C(11)-C(14)
C(1)-N(1)-C(14)-C(15)
C(1)-N(1)-C(14)-C(11)
C(10)-C(11)-C(14)-N(1)
C(10)-C(11)-C(14)-C(15)
N(1)-C(14)-C(15)-C(16)
C(11)-C(14)-C(15)-C(16)
C(14)-C(15)-C(16)-C(17)
C(15)-C(16)-C(17)-C(18)
C(15)-C(16)-C(17)-Cl(1)
0.1(9)
179.5(9)
176.1(9)
-3.1(17)
-173.8(10)
168.9(10)
-7.2(13)
Table 6. Intermolecular H-bonds geometry (Å, °) for dye 5
Table 7. Absorbency of dye 5 at lmax
Temperature/ °C
24.5 30.0 35.5
D-H¼
A
D-H
H¼
A
D¼
A
D-H¼
A
Concentration
× 10 /mol L
6
-1
C(2)-H(2)¼F(5)a
0.93
0.97
2.51
2.53
b
3.434
3.270
170
133
20.0
40.0
b
C(36)-H(36B)¼F(2)
2
.45
0.5006 0.4947 0.4859 0.4805 0.4876
0.7393 0.7313 0.7223 0.7173 0.7126
0.9687 0.9629 0.9616 0.9533 0.9509
1.1214 1.1148 1.1072 1.1064 1.0988
1.1960 1.1913 1.1840 1.1773 1.1696
a
Symmetry operation 1/2+x, 1/2-y, -z. Symmetry operation x,
3.66
4.88
1+y, z
5
6
.70
.10
6
82 nm is ascribed to monomer (M) band and the shoulder
peak at 634 nm is dimer band (D).
To determine the dimeric aggregation constant K
D
2
2
l /2K
A = (e
M
D
)(c/A) – e
M
l/2K
D
(1)
and the molar absorption coefficient e of the monomer si-
M
multaneously from the dependence of monomer band
where l represents solution thickness and c, the total dye
concentration. As is shown in Fig. 6, the dependence of A
on c/A shows a straight line relationship. Both the slope
absorbance A on total dye concentration c, according to the
2
4
Harris and Hobbs, we have
2
2
e
M
l /2K
D
and intercept – e
M
l/2K
3
D
are used to determine K
D
-1
5
-1
and e , which are 7.05 × 10 L·mol and 2.12 × 10 M ·
M
Fig. 5. Absorption spectra of dye 5 (concentration:
-
6
-1
6
.10 × 10 mol×L ) in 50 volume % aqueous
methanol solutions. a: 20.0 °C, b: 24.5 °C, c:
3
0.0 °C, d: 35.5 °C, e: 40.0 °C.
Fig. 6. Correlation of A with c/A for dye 5 at 20 °C.
508
www.jccs.wiley-vch.de
© 2013 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
J. Chin. Chem. Soc. 2013, 60, 503-510

JOURNAL OF THE CHINESE
CHEMICAL SOCIETY
Synthesis, Crystal and Properties of One Cyanine Dye
Table 8. Thermodynamic parameters of dimerization of dye 5 in 50 volume % aqueous methanol
solutions
-
3
-5
Temperature /
K
D
× 10
e × 10
Association
number n
DGD
DHD
DSD
M
-
1
-1
-1
-1
-1
-1 -1
°C
/L·mol
/M ·cm
/kJ·mol
/kJ·mol
/J·mol ·K
2
2
3
3
0.0
4.5
0.0
5.5
7.05
5.55
2.12
2.08
2.03
2.00
2.0
2.0
1.8
1.7
-21.6
-21.3
-20.8
-20.3
-46.0
-46.0
-46.0
-46.0
-83.2
-82.8
-82.9
-83.1
3.89
2.76
-
1
-1
cm for dye 5 at 20 °C in 50 volume % aqueous methanol
DH is calculated to be – 46.0 kJ mol for dye 5 between
D
solution.
20.0 and 35.5 °C in 50 volume % aqueous methanol solu-
Concentrations of monomer c
)/2 are calculated using either e and A or K
conventional plot of log c versus log c gives a straight
M
and dimer c
D
=
tions.
(
c–c
M
M
D
and c. A
The DG and DS values are obtained according to
D
D
D
M
thermodynamic equations DG = – RTlnK and DS =
D
D
D
line of slope approximately 2.0, as shown in Fig. 7, con-
firming that there is an equilibrium between monomer and
dimer in the dye solution, which can be described as:
(DH – DG )/T. The thermodynamic parameters are listed
D
D
in Table 8.
CONCLUSIONS
One benzoindole pentamethine cyanine dye was syn-
thesized and the spectral properties were investigated. The
max of the dye was in the region 682–689 nm in different
2
M Û D
Therefore
= c
(2)
l
solvents, and it typically exhibited a strong absorption in
near-infrared (NIR) region with large molar extinction co-
2
K
D
D
/c
M
(3)
5
-1
-1
efficients (e > 10 M cm ) in solutions. The X-ray diffrac-
tion study indicated that the p electrons in the dye mole-
cules were delocalized. Intermolecular hydrogen bonds
were displayed in the molecular system, which were effec-
tive in the molecular packing. The spectrophotometric de-
termination of aggregation behavior and thermodynamic
parameters of the dye in 50 volume % aqueous methanol
solutions was reported. The dimeric association constant
The K
D
values at different temperatures allow us to
, according to the Van’t Hoff equation:
calculate DH
D
d lnK
D
/d(1/T) = – DH
D
/R
(4)
-
1
-1
where R = 8.31 J mol K , the universal gas constant, and T
the Kelvin temperature. The plot of lnK versus 1/T, as
shown in Fig. 8, shows a straight line. From its slope the
D
Fig. 8. Correlation of lnK
D
with 1/T for dye 5 at differ-
Fig. 7. Correlation of lgc
D
with lgc
M
for dye 5 at 20 °C.
ent temperatures.
J. Chin. Chem. Soc. 2013, 60, 503-510
© 2013 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.jccs.wiley-vch.de
509

Article
Zhang et al.
K
D
, the dimeric free energy DG
D
, the dimeric entropy DS
D
,
S. S.; Lee, J. S. Dyes Pigments 2009, 80, 181.
0. Buurma, N. J.; Haq, I. J. Mol. Biol. 2008, 381, 607.
1. Miyashita, Y.; Mori, J.; Yokoyama, H.; Yoshikane, M.;
1
and the dimeric enthalpy DH were obtained.
D
1
Watanabe, H.; Takeuchi, K.; Kasai, H.; Nakanishi, H.;
Miyashita, T. J. Photochem. Photobiol., A 2008, 194, 129.
2. Abedin, K. M.; Álvarez, M.; Costela, A.; García-Moreno, I.;
García, O.; Sastre, R.; Coutts, D. W.; Webb, C. E. Opt.
Commun. 2003, 218, 359.
ACKNOWLEDGEMENTS
We appreciate the financial support for this research
by a grant from the Scientific and Technological Research
and Development Projects in Shaanxi Province (2012K07-
1
0
6) and the Special Science Research Foundation of Edu-
1
1
1
1
3. Wang, L.-Y.; Zhang, X.-G.; Shi, Y.-P.; Zhang, Z.-X. Dyes
Pigments 2004, 62, 21.
cation Committee (No.11JK0558).
4. Zhang, X.-H.; Wang, L.-Y.; Nan, Z.-X.; Tan, S.-H.; Zhang,
Z.-X. Dyes Pigments 2008, 79, 205.
REFERENCES
5. Liu, Q.; Wang, X.; Wang, L.-Y.; Fu, Y.-L.; Zhang, X.-H.
Dyes Pigments 2011, 9, 370.
1
2
3
. Metelev, V.; Zhang, S. R.; Tabatadze, D.; Bogdanov, Jr., A.
Bioconjugate Chem. 2011, 22, 759.
6. Fu, Y.-L.; Huang, W.; Li, C.-L.; Wang, L.-Y.; Wei, Y.-S.;
Huang, Y.; Zhang, X.-H.; Wen, Z.-Y.; Zhang, Z.-X. Dyes
Pigments 2009, 82, 409.
. Romieu, A.; Brossard, D.; Hamon, M.; Outaabout, H.; Por-
tal, C.; Renard, P. Y. Bioconjugate Chem. 2008, 19, 279.
. Bouteiller, C.; Clavé, G.; Bernardin, A.; Chipon, B.;
Massonneau, M.; Renard, P. Y.; Romieu, A. Bioconjugate
Chem. 2007, 18, 1303.
1
7. Chipon, B.; Clavé, G.; Bouteiller, C.; Massonneau, M.;
Renard, P. Y.; Romieua, A. Tetrahedron Lett. 2006, 47, 8279.
8. Shao, F.-W.; Yuan, H.-S.; Josephson, L.; Weissleder, R.;
Hilderbrand, S. A. Dyes Pigments 2011, 90, 119.
9. Dai, Z.-F.; Peng, B.-X. Dyes Pigments 1998, 36, 169.
0. Karstens, T.; Kobs, K. J. Phys. Chem. 1980, 84, 1871.
1. Sheldrick, G. M. SHELXS-97. Program for Solution Crystal
Structure, University of Göttingen: Germany, 1997.
2. Sheldrick, G. M. SHELXS-97. Program for Solution Crystal
Structure and Refinement, University of Göttingen: Ger-
many, 1997.
1
4
. Webster, S.; Fu, J.; Padilha, L. A.; Przhonska, O. V.; Hagan,
D. J.; Van Stryland, E. W.; Bondar, M. V.; Slominsky, Y. L.;
Kachkovski, A. D. Chem. Phys. 2008, 348, 143.
1
2
2
5
. Ata, A.; Matsuzawa, N. JP 03272890, 1991 [Chem. Abstr.
1
991, 116, 162619].
6
. Liao, W.-Y.; Hu, A.-T.; Huang, C.-L.; Yang, H.-W.; Chen,
Y.-C.; Yen, W.-H.; Jeng, T.-R.; Huang, D.-R.; Hu, D.-Y.;
Lee, M.-C. US 20020037474, 2002 [Chem. Abstr. 2002, 136,
2
2
86663].
2
3. Gong, Y.-K.; Wei, Y.-F.; Dang, G.-C.; Lv, Y.-P. J. Northwest
Univ. 1997, 27, 49.
7
8
. Huang, W.; Qian, H.-F. Dyes Pigments 2008, 77, 446.
. Kamaljit, S.; Aman, M.; Robinson W. T. Dyes Pigments
2
4. Harris Jr., J. T.; Hobbs, M. E. J. Am. Chem. Soc. 1954, 76,
2
007, 74, 95.
1
419.
9
. Lee, J. E.; Kim, H. J.; Han, M. R.; Lee, S. Y.; Jo, W. J.; Lee,
510
www.jccs.wiley-vch.de
© 2013 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
J. Chin. Chem. Soc. 2013, 60, 503-510