Effect of substituents and conjugated chain length on the UV spectra of α,ω-di-substituted phenyl polyenes

Article abstract of DOI:10.1002/poc.3178

A series of α,ω-di-substituted phenyl polyenes, p-X-Ph(CH = CH)_nPh-p-Y (n = 1, 2, or 3) were synthesized, and their ultraviolet (UV) absorption maximum wavelength were determined. The correlation between molecular structure and the maximum wavelength energy (wavenumber/cm ^-1) was carried out. The results show that the maximum wavelength energy of the title compounds is mainly affected by both substituent excited-state parameters and maximum wavelength energy of the parent molecule. However, the two influence factors are not independent, and the action of substituent is governed by the parent molecular absorption energy. In the case of the compounds containing NO₂ or NH₂ groups, the influence of interaction of polarity parameters on the maximum wavelength energy must also be considered. In addition, the exploration was also made for the quantifying correlation of UV absorption maximum wavelength energy with the conjugated polarizability potential CPP replacing the parent molecular absorption energy. And the results indicate that the equation with CPP parameters is more accurate and convenient. Copyright 2013 John Wiley & Sons, Ltd. For the α,ω-di-substituted phenyl polyenes, p-X-Ph(CH = CH)_nPh-p-Y (n = 1, 2, or 3), their ultraviolet absorption maximum wavelength energy (wavenumber/cm^-1) was mainly affected by both substituent excited-state parameters and maximum wavelength energy of the parent molecule. However, the two influence factors are not independent, and the action of substituent is governed by the parent molecular absorption energy. Copyright

Full text of DOI:10.1002/poc.3178

Research Article
Received: 27 April 2013,
Revised: 9 June 2013,
Accepted: 23 June 2013,
Published online in Wiley Online Library: 30 July 2013
(wileyonlinelibrary.com) DOI: 10.1002/poc.3178
Effect of substituents and conjugated chain
length on the UV spectra of α,ω-di-substituted
phenyl polyenes
Chenzhong Caoa*, Yun Zhua and Guanfan Chena
A series of α,ω-di-substituted phenyl polyenes, p-X–Ph(CH = CH)nPh–p-Y (n = 1, 2, or 3) were synthesized, and their
ultraviolet (UV) absorption maximum wavelength were determined. The correlation between molecular structure
and the maximum wavelength energy (wavenumber/cmꢀ1) was carried out. The results show that the maximum
wavelength energy of the title compounds is mainly affected by both substituent excited-state parameters and max-
imum wavelength energy of the parent molecule. However, the two influence factors are not independent, and the
action of substituent is governed by the parent molecular absorption energy. In the case of the compounds
containing NO2 or NH2 groups, the influence of interaction of polarity parameters on the maximum wavelength
energy must also be considered. In addition, the exploration was also made for the quantifying correlation of UV
absorption maximum wavelength energy with the conjugated polarizability potential CPP replacing the parent
molecular absorption energy. And the results indicate that the equation with CPP parameters is more accurate
and convenient. Copyright © 2013 John Wiley & Sons, Ltd.
Supporting information may be found in the online version of this paper
Keywords: di-substituted phenyl polyenes; UV spectra; substituent effects; repeating unit number; conjugated polarizability
potential
sorts of electronic activities of organic homologues. Studies on
the substituent effects on the UV absorption spectra also re-
INTRODUCTION
ceived a lot of achievements, which mainly adopted the fixed
parent molecular skeleton and used the substituent parameters
to quantify the UV absorption energy. Recently, Cao et al.[9] pro-
Design and synthesis of the compounds with good optical per-
formance have been an important field of research on optical
functional materials. Because organic optical materials have bet-
ter designing and cutting property than inorganic optical mate-
rials,[1,2] they have attracted much more attention from
researchers who study on optical functional materials. Molecular
design of good optical materials depends on the determination
of quantitative relationship between the molecular structure
and absorption (or emission) spectra. Therefore, the optimal
use of an optical material needs an accurate prediction of the ab-
sorption (or emission) spectra in advance. Organic conjugated
compound with large π system has good Ultraviolet–visible
(UV–vis) absorption properties and is the preferred compound
in organic optical materials. The quantitative relationship be-
tween their molecular structure and optical properties not only
has important theoretical significance, but also has important
application value.
With regard to the molecular structure, the parent molecular
skeleton and substituents are the main factors to dominate the
UV absorption energy of conjugated organic compounds. In
the past decades, chemists made numerous researches[3–8] on
the change rules of UV absorption from two aspects, substituent
effects and the structural repeating unit of conjugated molecular
chain, respectively. The organic homologous linear regularity
proposed by Jiang Mingqian[8] expressed the influence of struc-
tural repeating unit number (i.e. chain length) on the UV absorp-
tion spectra within a series of compounds when the substituents
are fixed and obtained good application in evaluating various
ex
posed excited-state substituent constants σ and made a new
CC
progress in quantifying the effect of substituents on parent mo-
lecular UV absorption energy.
In the conjugated organic compounds, the small molecules,
such as α,ω-di-substituted phenyl polyenes (DPPs), have aroused
ones' great interest; their nonlinear optics and fluorescence
emission spectra received a large number of studies.[10–14] As
we know, nonlinear optics and fluorescence emission spectra
of compounds are the performance of molecules excited by ab-
sorption light. Thus, understanding UV–vis absorption spectral
change rule of DPPs also has important theoretical significance
and practical value. Whereas, the previous researches on optical
properties of DPPs focus mainly on one of the above mentioned
two influence factors, i.e. the substituents or conjugated chain
structural repeating unit number, respectively. What we are
more concerned about is if both the substituents and the
* Correspondence to: Chenzhong Cao, School of Chemistry and Chemical Engi-
neering, Hunan University of Science and Technology, Xiangtan, 411201, China.
E-mail: czcao@hnust.edu.cn
a C. Cao, Y. Zhu, G. Chen
School of Chemistry and Chemical Engineering, Hunan University of Science
and Technology, Key Laboratory of Theoretical Chemistry and Molecular Sim-
ulation of Ministry of Education, Hunan Provincial University Key Laboratory of
QSAR/QSPR, Xiangtan 411201, China
J. Phys. Org. Chem. 2013, 26 834–839
Copyright © 2013 John Wiley & Sons, Ltd.

UV SPECTRA OF α,ω-DI-SUBSTITUTED PHENYL POLYENES
structural repeating unit number of a series of DPPs change si-
multaneously, their UV–vis absorption spectra change follows
what rule. Is there the simple sum of the substituent effects
and action of structural repeating unit? This paper tries to ex-
plore this topic and got some meaningful results.
RESULTS AND DISCUSSION
The main factors influencing the UV absorption energy of
DPPs
For the title compounds p-X–Ph(CH = CH)nPh–p-Y shown in Fig. 1,
both their substituents (X and Y) and the structural repeating unit
number (n) are in change; thus, the influence of the two factors
on UV absorption should be first considered. Chen et al.[18] inves-
tigated the conjugated compounds with molecular structure of
p-X–Ph (CH = CHPh)n–p-Y (n = 0, 1, or 2; X and Y are substituents),
and proposed Eqn (1) to quantitatively describe the influence of X
and Y groups and structural repeating unit number on the UV
DATA SET
Molecular structure of DPP derivatives is p-X–Ph(CH = CH)nPh–p-Y (as
shown in Fig. 1), in which n= 1 is the para-substituted styrenes (SBs,
Nos. 1–21 of Table 1), n= 2 is the para-substituted phenyl butadienes
(DPBs, Nos. 22–41 of Table 1), and n= 3 is the para-substituted phenyl
hexatrienes (DPHs, Nos. 42–51 of Table 1). Their absorption maximum
wavelength λmax of UV–vis spectra and the corresponding
wavenumber υmax are listed in Table 1. Some substituent parameters
are listed in Table 2.
absorption maximum wavelength energy υmax
.
¼ 8827:27 þ 0:0686∑σex ꢁυmax;parent
υmax
CC
n
ex
ꢀ0:0117ðꢀ1Þ σ ðXYÞꢁυmax;parent
(1)
CC
þ0:7246υmax;parent
R ¼ 0:9937; s ¼ 506; F ¼ 2559:63; n ¼ 101
Where υmax,parent is the UV absorption maximum wavelength
energy of the parent compound, n for structural repeating
ex
unit number, ∑σ for the sum of excited-state substituent
CC
ex
ex
ex
CC
Figure 1. Molecular structure of α,ω-di-substituted phenyl polyenes (DPPs)
parameters of X and Y groups (i.e. ∑σCC ¼ σCCðXÞ þ σ ðYÞ ),
Table 1. The absorption maximum wavelength λmax and corresponding wavenumber υmax of UV–vis spectra of α,ω-di-substituted
phenyl polyene derivatives in absolute alcohol
No.
Compounda
λmax (nm)
υmax (cmꢀ1
)
No.
Compounda
λmax (nm)
υmax (cmꢀ1
)
1
2
3
4
5
6
7
8
HSBH
HSBF
HSBCl
HSBMe
HSBOMe
HSBCN
FSBF
FSBCl
307.8
307.4
312.1
311.2
318.2
320.5
307.7
312.3
311.3
318.4
320.8
316.7
316.4
323.8
324.1
314.9
321.2
326.6
325.6
338.3
342.9
345.8
345.7
350.9
349.7
353.8
32485
32536
32044
32133
31427
31204
32501
32018
32121
31403
31175
31576
31611
30883
30855
31755
31129
30621
30716
29562
29163
28918
28929
28501
28596
28265
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
HDPBCN
HDPBCF3
FDPBCl
FDPBMe
FDPBOMe
ClDPBCl
ClDPBMe
ClDPBOMe
ClDPBCN
ClDPBCF3
MeDPBMe
MeDPBOMe
MeDPBCN
MeDPBCF3
MeODPBOMe
HDPHH
361.5
349.1
350.6
349.3
354.0
355.8
354.7
359.6
364.7
353.9
352.9
360.6
367.5
353.6
362.5
371.3
375.8
374.6
379.0
368.0
379.1
375.2
385.0
395.3
376.7
27666
28649
28527
28627
28248
28104
28193
27809
27417
28260
28333
27729
27212
28277
27585
26930
26613
26696
26382
27177
26381
26651
25971
25300
26545
9
FSBMe
FSBOMe
FSBCN
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
ClSBCl
ClSBMe
ClSBOMe
ClSBCN
MeSBMe
MeSBOMe
MeSBCN
MeOSBOMe
MeOSBCN
CNSBCN
HDPBH
HDPBF
HDPHCl
HDPHMe
HDPHOMe
FDPHF
ClDPHCl
MeDPHMe
MeODPHOMe
CNDPHCN
CF3DPHCF3
HDPBCl
HDPBMe
HDPBOMe
aThe data of compounds Nos. 1–21 are from the papers[3,15] reported by authors, the rest were synthesized and determined by this
work. All kinds of compounds are illustrated as follows: FSBCl represents p-F–Ph(CH = CH)nPh–p-Cl; FDPBCl for p-F–Ph(CH = CH)2
Ph–p-Cl; FDPHF for p-F–Ph(CH= CH)nPh–p-F.
J. Phys. Org. Chem. 2013, 26 834–839
Copyright © 2013 John Wiley & Sons, Ltd.
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C. CAO, Y. ZHU AND G. CHEN
ex
CC
Table 2. The excited-state substituent parameters σ and polarity parameters σp (Hammett constant) of some substituents
H
F
Cl
Br
Me
Et
MeO
NH2
CF3
CN
NO2
SO2Me
a
ex
σ
σ
0.00
0.00
0.06
0.06
ꢀ0.22
ꢀ0.33
ꢀ0.17
ꢀ0.17
ꢀ0.13
ꢀ0.15
ꢀ0.50
ꢀ0.27
ꢀ0.88
ꢀ0.66
ꢀ0.12
ꢀ0.70
ꢀ1.17
ꢀ0.43
CC
b
0.23
0.23
0.54
0.66
0.78
0.72
p
aData is from ref..[16]
bData is from ref..[17]
ex
ex
two parameters, ∑σ ꢁυmax;parent and υmax,parent, we obtained
and σ ðXYÞ is the interaction term of X and Y groups
CC
CC
ex
CC
ex
CC
ex
CC
(i.e. σ ðXYÞ ¼ σ ðXÞꢂσ ðYÞ ). Equation (1) shows that the
regression Eqn (4).
structural repeating unit number appears as an alternant influence
on the UV absorption maximum wavelength energy of the men-
tioned series of compounds. Thus, we first thought, the UV absorp-
tion maximum wavelength energy change rule of the title
compounds may be similar to that of the conjugated system
reported by Chen.[18] Therefore, using the same method to corre-
late the υmax of the title compounds, we obtained Eqn (2).
υmax ¼ 1556:30 þ 0:0568∑σeCxCꢁυmax;parent þ 0:9464υmax;parent (4)
R ¼ 0:9961; s ¼ 187; F ¼ 3093:71; n ¼ 51
The correlation of Eqn (4) is better than that of Eqn (3) or (2). It
indicates that the effect of interaction of groups on UV absorp-
tion energy of DPPs also can be ignored, and the effect of struc-
tural repeating unit number on their UV absorption energy is not
an alternant effect.
In addition, we test whether the UV absorption maximum
wavelength energy of DPPs is independently affected by the
substituents and the structural repeating unit number, namely
removing the υmax,parent part of right second item in Eqn (4) (only
using the ∑σeCxC) to carry out a regression, we obtained Eqn (5).
υmax ¼ 1511:15 þ 0:0554∑σeCxCꢁυmax;parent
n
ex
CC
þ0:0075ðꢀ1Þ σ ðXYÞꢁυmax;parent (2)
þ0:9476υmax;parent
R ¼ 0:9962; s ¼ 187; F ¼ 2057:36; n ¼ 51
Equation (2) has a good correlation, but further analysis
shows that the statistic t values of the three variables
υmax ¼ 2347:92 þ 1687:18∑σeCxC þ 0:9196υmax;parent
(5)
n
ex
∑σ ꢁυmax;parent , ðꢀ1Þ σeCxCðXYÞꢁυmax;parent , and υmax,parent of Eqn
CC
R ¼ 0:9946; s ¼ 221; F ¼ 2192:85; n ¼ 51
(2) were 20.30, 0.93, and 77.73, respectively. It indicates that
the parent molecular υmax,parent plays a major role in UV
absorption of DPP derivatives, which is consistent with the known the-
The correlation of Eqn (5) is worse than that of Eqn (4). It shows
that the influence of substituent effects on υmax is not completely
independent, and it is dominated by the parent molecular elec-
tronic transition energy, namely the larger UV absorption energy
of the parent molecule will cause a relative larger substituents ef-
fect. Cao et al.[3] have recommended using polarity parameter
σXY [i.e. σXY = σp(X) × σp(Y)] to express the interaction of X and Y
groups. Here, we also try to add this parameter to Eqn (4) and carry
out a regression; the obtained result is worse than Eqn (4). It indi-
cates that the item σXY has no substantial contribution to the UV
absorption energy of DPPs. From the above analysis, we can say
that Eqn (4) can be used to describe the UV absorption maximum
wavelength energy change of DPPs derivatives in general.
n
ex
CC
ory. While the right third item of Eqn (2), ðꢀ1Þ σ ðXYÞꢁυmax;parent
,
expressing substituent interaction and alternant change of the UV
absorption, has little effect. Therefore, we speculate that the alternant
change of UV absorption maximum wavelength energy may not exist
in the DPP system as the structural repeating unit number n changes.
Thus, removing the correction factor (ꢀ1)n in the item
n
ex
CC
ðꢀ1Þ σ ðXYÞꢁυmax;parent , we carried out regression analysis once
again for the same 51 samples and obtained Eqn (3).
υmax ¼ 1588:24
(3)
ex
þ0:0535∑σ ꢁυmax;parent ꢀ 0:0125σeCxCðXYÞꢁυmax;parent
CC
þ0:9447υmax;parent
Validating the reliability of the correlation equation
R ¼ 0:9962; s ¼ 187; F ¼ 2057:97; n ¼ 51
In order to test the reliability of Eqn (4), we predicted the UV
absorption maximum wavelength energy of some DPPs com-
pounds which did not appear in Eqn (4), some of them are from
literature, some of them are synthesized and determined by au-
thor's research team. The predicted results are shown in Table 3.
As can be seen from Table 3, most of the predicted values by
Eqn (4) are in good agreement with the experimental results. It
should pointed out that the UV spectral data of Nos. 1–5 com-
pounds were measured in 95% ethanol, while the data used in
Eqn (4) are measured in absolute alcohol, and there are
differences in solvent effect. As an approximate reference, the
The correlation of Eqn (3) versus Eqn (2) is not improved. The
statistic t values of the right second, third, and fourth items of
Eqn (3) are 12.82, ꢀ0.94, and 76.96 values, respectively. It shows
ex
CC
that the effect of the third item, σ ðXYÞꢁυmax;parent, is still very
small. That is to say, this item can be removed from the correla-
tion equation, and the UV absorption maximum wavelength
energy of p-X–Ph(CH = CH)nPh–p-Y (DPPs) has different change
rule from that of the p-X–Ph(CH = CHPh)n–p-Y. Thus, using
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UV SPECTRA OF α,ω-DI-SUBSTITUTED PHENYL POLYENES
Table 3. The experimental value λmax,expt. (nm) and the predicted value λmax,pred. (nm) of UV absorption maximum wavelength for
some DPPs
a
b
c
ex
CC
ex
CC
No.
Compound
λmax,expt.
υmax,parent
σ
ðXÞ
σ
ðYÞ
λmax,pred.
Δλmax
1
2
3
4
5
6
7
8
MeOSBSO2Me
MeSBSO2Me
HSBSO2Me
ClSBSO2Me
BrSBSO2Me
MeSBEt
HSBEt
FSBEt
ClSBEt
CF3SBNO2
CF3SBNH2
NH2SBNH2
Cl SBNH2
CNSBNH2
332.0
323.1
316.0
320.3
321.3
315.2
312.0
311.5
316.7
340.0
349.1
344.0
341.2
367.8
32485
32485
32485
32485
32485
32485
32485
32485
32485
32485
32485
32485
32485
32485
ꢀ0.5
ꢀ0.43
ꢀ0.43
ꢀ0.43
ꢀ0.43
ꢀ0.43
ꢀ0.13
ꢀ0.13
ꢀ0.13
ꢀ0.13
ꢀ1.17
ꢀ0.88
ꢀ0.88
ꢀ0.88
ꢀ0.88
327.0
320.6
317.4
321.5
323.6
315.0
311.9
310.8
315.9
334.2
328.3
344.2
330.3
340.3
5.0
2.5
ꢀ1.4
ꢀ1.2
ꢀ2.3
0.2
0.1
0.7
0.8
5.8
ꢀ0.17
0.00
ꢀ0.22
ꢀ0.33
ꢀ0.17
0.00
0.06
9
ꢀ0.22
ꢀ0.12
ꢀ0.12
ꢀ0.88
ꢀ0.22
ꢀ0.70
10
11
12
13
14
20.8
ꢀ0.2
10.9
27.5
aThe data of compounds Nos. 1–5 are from ref.,[19] the rest were synthesized and determined by this workgroup.[3,20]
bPredicted values with Eqn (4).
cΔλmax = λmax,expt. ꢀ λmax,pred.
predicted values are consistent with the experimental ones. How-
ever, the predicted results in Table 3 caused our attention: the error
of those compounds containing NO2 or NH2 group is relatively
large; especially the error of CNSBNH2 is up to 27.5 nm. Perhaps,
the NO2 or NH2 group can form a hydrogen bond with the solvent
ethanol, which is similar to the action of the OH or N(Me)2
group.[18] Maybe, the polarity parameters of groups in these com-
pounds also play an important role. For example, when we took
the UV spectral data of Nos. 1–51 in Table 1 together with Nos.
6–14 in Table 3 as data set (namely a total of 60 samples) and
use the same parameters in Eqn (4) to carry out regression analysis,
correlation Eqn (6) was obtained.
Therefore, Eqn (7) expresses the change rule of UV absorption
maximum wavelength energy υmax of the title compounds.
Using Eqn (7) to calculate the used 60 samples of compounds,
we got the mean absolute error 1.6 nm between the calculated
wavelength values and the experimental ones, which is within
the experimental uncertainties.
It should be pointed out that the establishment of the quanti-
tative relationship like Eqn (7) must be known of the absorption
maximum wavelength energy υmax,parent of the parent molecule
DPP with a given structural repeating unit number n. otherwise,
it is difficult to establish the correlation equation. In addition, the
υ
,
max parent is experimentally obtained, and the experimental error
is inevitable. If the parent molecular υmax parent can be replaced
,
υmax ¼ 2284:89 þ 0:0677∑σeCxCꢁυmax;parent þ 0:9250υmax;parent (6)
R ¼ 0:9824; s ¼ 391; F ¼ 790:21; n ¼ 60
by a theoretical parameter, the establishment of correlation
equation should be more convenient. Cao et al.[21] studied on
the correlation between the UV absorption energy of organic
conjugated compounds and the conjugated polarizability poten-
tial CPP and got good results. If the conjugated polarizability
potential CPP can be applied in quantifying UV absorption en-
ergy change of the DPPs, their quantitative correlation of υmax
can also be carried out expediently in a wider distribution of
Compared with Eqn (4), the regression result of Eqn (6) is
much bad. Therefore, we introduced a new parameter Δσ2 to
correlate the υmax of compounds containing NO2 or NH2 group.
Here, Δσ = σX ꢀ σY, its value is calculated as follows: for the mol-
ecules containing no NO2 and NH2, their Δσ2 are not to be con-
sidered, namely Δσ = 0. Adding Δσ2 to Eqns (4) and (5), we
employed three parameters to carry out regression for the same
60 samples used in Eqn (6) and got Eqns (7) and (8), respectively.
υmax ¼ 1662:27 þ 0:0576∑σeCxCꢁυmax;parent þ 0:9430υmax;parent (7)
ꢀ1231:72Δσ2
R ¼ 0:9963; s ¼ 182; F ¼ 2485:25; n ¼ 60
υmax ¼ 2482:73 þ 1754:10∑σeCxC þ 0:9158υmax;parent
(8)
ꢀ1293:03Δσ2
R ¼ 0:9947; s ¼ 217; F ¼ 1743:14; n ¼ 60
The correlation of Eqn (7) is good as same as that of Eqn (4),
while the correlation of Eqn (8) is worse than that of Eqn (7),
and the reason has been mentioned in the discussion on Eqn (5).
Figure 2. The plot of the predicted UV absorption maximum wavelength
energy (wavenumber υmax) versus experimental ones for the 60 samples
of p-DPPs (○) and another 18 samples of m-SBs (△, data are from ref.[16]
)
J. Phys. Org. Chem. 2013, 26 834–839
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C. CAO, Y. ZHU AND G. CHEN
Figure 3. Synthetic routes of target compounds (DPPs) with repeating unit number 2 and 3
the structural repeating unit number n for DPPs. It is known that
parameters interaction term Δσ2 of substituents X and Y on
the UV absorption. In addition to the NO2 or NH2 groups,
should any other groups be considered the effect of item
Δσ2 on the υmax, it is not yet clear and needs to be further
studied. The alternant effect of structural repeating unit num-
ber on the UV absorption energy was not observed in the
DPPs series. When the parent molecular UV absorption maxi-
the CCP values are 1, 0.6667, and 0.5111 for the conjugated poly-
ene with n = 1, 2, or 3, respectively. Using these CCP values to re-
place the υmax parent values of the corresponding parent
,
molecules with structural repeating unit number (C = C double
bond number) 1, 2, or 3, lead their CCP into Eqn (7) and carry
out a regression once again. Equation (9) was obtained.
mum wavelength energy υmax pare was directly replaced by
,
υmax ¼ 21285:95 þ 2075:06∑σeCxCꢁCPP
þ11144:28CPP ꢀ 1144:09Δσ2
(9)
the conjugated polarizability potential parameters CPP to cor-
relate the υmax of DPPs, good results can also be obtained. Fur-
thermore, the establishment of correlation equation with CCP
is more convenient, which can overcome the difficulty of using
R ¼ 0:9972; s ¼ 157; F ¼ 3346:65; n ¼ 60
experimental υmax pare of parent molecule.
,
Equation (9) also has good correlation. It can be used to pre-
dict the UV absorption maximum wavelength energy υmax of
the title compounds, which avoid the difficulty to use experi-
EXPERIMENTAL SECTION
mental parent molecular υmax parent as parameter, and it is more
,
Synthesis of the title compounds
accurate than Eqn (7). The υmax of the used 60 samples of title
compounds and another 18 samples of meta-substituent from
3,3′-di-substituted stilbenes (m-SBs) reported by Cao[16] were
predicted; then, these υmax values were converted into wave-
length λmax values. The mean absolute error between the pre-
dicted wavelength values and the experimental ones are 1.4
nm and 1.2 nm, respectively. The plot of the predicted values
versus experimental ones is shown in Fig. 2.
The DPP derivatives were prepared by Wittig-Horner[22] method, in which
the para-substituted phenyl butadienes (DPBs) were from the benzyl
chloride, the para-substituted phenyl hexatrienes (DPHs) were from the
cinnamyl chloride, and the symmetric DPHs are synthesized by reaction
of 1,4-dibromo-2-butene with triethylphosphite ester and then with
para-substituted benzaldehyde.[23] Synthetic routes for the above three
kinds of compounds were shown in Fig. 3.
It can be seen intuitively from Fig. 2 that the predicted values with
Eqn (9) are in good agreement with the experimental ones. Thus, we
recommend Eqn (9) as the model equation to evaluate the UV ab-
sorption maximum wavelength energy υmax of the title compounds.
Determination of UV absorption spectra
The used solvent is fully dried by anhydrous MgSO4, and the sample with
mass concentration of solution about 2.000 g/L is prepared for determi-
nation. All solutions were prepared freshly, and UV–vis absorption spec-
tra were recorded in Perkin-Elmer Lambda 35 UV spectrophotometer.
Determination of process is carried out in the dark condition, using eth-
anol as the reference solution; UV–vis absorption maximum wavelength
λmax of the title compounds was measured (and then converted corre-
sponding wavenumber υmax). Determination was repeated three times
for each sample, and then its average value of λmax was obtained. The
obtained results were listed in Table 1.
CONCLUSIONS
For the DPPs with molecular structure of p-X–Ph(CH = CH)nPh–
p-Y, their UV absorption maximum wavelength energy υmax
were mainly affected by the UV absorption maximum wave-
length energy of the parent molecule(υmax,parent) and the
ex
CC
excited-state parameters of substituents X and Y(σ ). These
two influence factors are not independent, and the action of
ex
CC
σ
is governed by the υmax,parent. It shows that the larger
SUPPORTING INFORMATION
The 1H NMR of the α,ω-di-substituted phenyl polyene deriva-
UV absorption energy of the parent molecule will cause a
relatively larger substituents effect. If DPPs contain NO2 or
NH2 groups, it also needs to consider the effect of polarity
tives (DPPs).
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J. Phys. Org. Chem. 2013, 26 834–839

UV SPECTRA OF α,ω-DI-SUBSTITUTED PHENYL POLYENES
[9] C. Z. Cao, G. F. Chen, Z. Q. Yin, J. Phys. Org. Chem. 2008, 21, 808.
[10] Y. Sonoda, S. Tsuzuki, M. Goto, et al. Phys. Chem. A. 2010, 114,
172.
[11] A. K. Singh, G. R. Mahalaxmi, Photochem. & Photobio. 2000, 71, 387.
[12] J. Catalán, J. Chem. Phys. 2007, 335, 69.
Acknowledgements
This work was supported by the National Natural Science
Foundation of China (Nos. 21272063, 21072053) and the Scientific
Research Fund of Hunan Provincial Education Department (10K025).
[13] M. Q. Zhu, Z. Gu, R. Zhang, J. N. Xiang, S. M. Nie. Talanta. 2010,
81, 678.
[14] H. El-Gezawy, W. Rettig, R. Lapouyade. J. Phys. Chem. A 2006, 110, 67.
[15] L. Y. Wang, C. Z. Cao, Y. Zhu, J. Hunan Univ. Sci. & Tech. (Nat. Sci. Ed.)
2012, 27, 96.
[16] C. Z. Cao, B. Sheng, G. F. Chen, J. Phys. Org. Chem. 2012, 25, 1315.
[17] C. Hansch, A. Leo, R. W. Taft, Chem. Rev. 1991, 91, 165.
[18] G. F. Chen, C. Z. Cao, J. Phys. Org. Chem. 2010, 23, 776.
[19] X. K. Jiang, G. Z. Ji, D. Z. R. Wang, J. R. Y. Xie, J. Phys. Org. Chem. 1995,
8, 781.
[20] Z. J. Fang, C. Z. Cao, G. F. Chen, J. Phys. Org. Chem. 2012, 25, 1343.
[21] C. Z. Cao, Y. B. Lin, Chin. J. Chem. Phys. 2004, 17, 703.
[22] X. F. Liu, H. B. Liu, W. D. Zhou, et al. Langmuir 2010, 26, 3179.
[23] D. Pfiffi, B. A. Bier, et al. J. Phys. Chem. A 2010, 114, 4099.
REFERENCES
[1] L. R. Dalton, P. A. Sullivan, D. H. Bale, Chem. Rev. 2010, 110, 25.
[2] Y. Cui, Y. F. Yue, G. D. Qian, B. L. Chen, Chem. Rev. 2012, 112, 1126.
[3] C. Z. Cao, G. F. Chen, Y. X. Wu, Sci. Chi. Ser. B-Chem. 2011, 54, 1735.
[4] X. K. Jiang, Acc. Chem. Res. 1997, 30, 283.
[5] X. K. Jiang, G. Z. Ji, D. Z. R. Wang, J. Phys. Org. Chem. 1995, 8, 143.
[6] V. Papper, D. Pines, G. Likhtenshtein, E. Pines, J. Photochem. &
Photobio. A. 1997, 111,87.
[7] A. Taherpour, F. Shafiei, J. Mol. Struct. (THEOCHEM) 2005, 726, 183.
[8] M. Q. Jiang. Homologous linear regularities for homologous organic
compound. Beijing: Science Press, 1980
J. Phys. Org. Chem. 2013, 26 834–839
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