The electronic structure, solvatochromism, and electric dipole moments of new Schiff base derivatives using absorbance and fluorescence spectra

Article abstract of DOI:10.1007/s11224-018-1228-8

The electronic structure and electronic transitions of four new mono Schiff base derivatives are interpreted by using absorption and fluorescence spectra including 28 different solution medium. Electrical dipole moments have been found by means of four di

Full text of DOI:10.1007/s11224-018-1228-8

Structural Chemistry
https://doi.org/10.1007/s11224-018-1228-8
ORIGINAL RESEARCH
The electronic structure, solvatochromism, and electric dipole moments
of new Schiff base derivatives using absorbance
and fluorescence spectra
Yadigar Gülseven Sıdır1 & Cebrail Aslan2 & Halil Berber3 & İsa Sıdır1
Received: 9 August 2018 /Accepted: 2 November 2018
#
Springer Science+Business Media, LLC, part of Springer Nature 2018
Abstract
The electronic structure and electronic transitions of four new mono Schiff base derivatives are interpreted by using absorption
and fluorescence spectra including 28 different solution medium. Electrical dipole moments have been found by means of four
different quantum mechanical methods based on solvatochromic shifts like Lippert–Mataga, Bakhshiev, modified Bilot–Kawski,
and Reichardt methods. Quantitative researches of solvent-solute interactions are done by using Kamlet–Taft and Catalan
parameters. In absorption and fluorescence spectra, bathochromic shift occurs with dispersion-polarization forces effect. The
electronic transitions and electronic structure of these molecules have changed to dependent on solvent medium property.
HOMO, LUMO, MEP, and SAS were calculated using B3LYP/6-311G(d,p) level of theory. Solvatochromism, photophysical
properties, and electronic structure were discussed in detail. The dipole moments in ground-state and excited-state have not
almost change.
.
.
.
.
Keywords Kamlet-Taft solvatochromism Catalan solvatochromism Electrical dipole moment Electronic transitions
Photophysical properties Schiff bases
.
Introduction
having novel and fresh usage areas, because the electronic and
molecular structure of Schiff bases and compounds having
Schiff bases nucleus have own. The more interesting usage
areas from Schiff bases compounds and complex are biolog-
ical activity such as anticancer, antioxidant [6–8], antiviral
[9–11], antifungal [12–14], antibacterial [15, 16], antimicro-
bial [17–19], genotoxic [20], and antiproliferative properties
[21–24]. The Schiff bases like push-pull systems have very
different properties such as organic photovoltaic materials [25,
26], membrane sensors [27–34], non-linear optic materials
[35–39], chemosensor properties [40–45], photochromism
properties [46–48], optical switching devices [49],
solvatochromic properties [50–55], fluorescent materials [56,
57], and liquid crystal properties [58–60]. Thus, electronic
structures of these group molecules and novel derivatives need
to be examined in detail.
Schiff bases are compounds containing the azomethine group
(–RC = N–) and are usually compounds in which the primary
amine occurs as a result of condensation reaction with an
active carbonyl. There are a number of studies on compounds
known as Schiff bases [1–5]. These compounds have a lot of
usage areas and are still an intensive research topic, whether
Electronic supplementary material The online version of this article
(https://doi.org/10.1007/s11224-018-1228-8) contains supplementary
material, which is available to authorized users.
* Yadigar Gülseven Sıdır
ygsidir@beu.edu.tr; yadigar.gulseven@gmail.com
The electric dipole moments of molecules are very important
from physical parameters due to the dipole moment values that
provide information about the change in the electronic distribu-
tion and electronic change during excitation. The most common
method used experimentally to determine electric dipole mo-
ments is quantum mechanical method done with using
solvatochromic shifts in spectrums. The dipole moments are
1
Department of Physics, Faculty of Arts and Science, Bitlis Eren
University, 13000 Bitlis, Turkey
2
Department of Physics, Science Institute, Bitlis Eren University,
13000 Bitlis, Turkey
3
Department of Chemistry, Faculty of Science, Anadolu University,
26470 Eskişehir, Turkey

Struct Chem
calculated using Lippert–Mataga [61, 62], Bakhshiev [63],
Reichardt [64], and modified Bilot–Kawski [65–71] methods.
Solvatochromism has researched to changes in the electronic
structures of molecules depending on their solvent environ-
ment. Compounds having solvatochromic properties are mole-
cules that can be used during organic electronics, optical
switching, and processes in which electrons actively act. The
statistical analysis of solvatochromism, in that, another name is
LSERs (linear solvation energy relationships), done using
Kamlet–Taft [72, 73] and Catalan parameters [75–77], and
physical and solution parameters done on solvent-solute inter-
actions in different medium during excitation could be calcu-
lated to qualitative effects [77, 78].
Thus, it must be determined in Schiff bases and their deriv-
atives. In this study, the electronic structure, solvatochromism,
and electric dipole moment of four new Schiff base molecules
titled as (E)-2-(2,5-dimethoxybenzylideneamino)phenol (S1),
(E)-4-(3,4-dimethoxybenzylideneamino)phenol (S2), (E)-
N-(2,4-dimethoxybenzyliden)benzeneamine (S3), and (E)-
4-(2,4-dimethoxybenzylideneamino)phenol (S4) molecules
were determined after these molecules were synthesized and
characterized. The absorbance (UV) and fluorescence spectra
of Schiff base derivatives were measured at room temperature
in 28 different solvents with different polarities. Solvent-solute
interactions of the molecules are analyzed by using Kamlet–
Taft and Catalan solvatochromism, which are LSER models.
Using the values obtained from the Kamlet–Taft and Catalan
solvatochromism, the quantities involved in solvent-solute in-
teractions such as solvent polarity, solvent dipolarity, solvent
acidity, and solvent basicity, dispersion-induction interaction,
and dipolar-orientation interaction were compared with each
other. The excited- and ground-state electric dipole moments
are calculated by the methods of Lippert–Mataga, Bakhshiev,
modified Bilot–Kawski, and Reichardt, respectively. Ground-
state and excited-state dipole moments, HOMO, LUMO, SAS,
and MEP shape, have been calculated by using DFT (B3LYP)
method and 6-311G(d,p) basis set in gas phase.
Synthesis of 2-((2,5-dimethoxybenzylidene)amino)phenol
(S1)
2-Aminophenol (1.091 g (0.01 mol)) was dissolved gently in
25 mL of MeOH to complete dissolution of the material. To this
solution, 1.661 g (0.01 mol) of 2,5-dimethoxybenzaldehyde
solution in 25 mL of MeOH was slowly added with stirring.
The crude product was filtered and purified by recrystallization
from methyl alcohol, and the vacuum was dried in a desiccator.
IR (KBr, disc, ν cm−1): 3375 (O–H), 3304–3000 (C–H,
aromatic), 2957–2834 (C–H, aliphatic), 1591 (C=N), 1495–
1
1379 (C=C, aromatic), 1222 (C–O, aromatic). H NMR
(300 MHz, DMSO) δ 9.01 (s, 1H), 8.94 (s, 1H), 7.80 (s, 1H),
7.13 (m, 1H), 7.08 (s, 1H), 7.08 (s, 1H), 6.92 (m, 1H), 6.88 (m,
1H), 6.85 (m, 1H), 3.84 (s, 2H), 3.80 (s, 3H). 13C NMR
(75 MHz, DMSO) δ 163.44 (s), 154.49 (s), 153.72 (s),
151.58 (s), 144.46 (s), 127.77 (s), 125.14 (s), 120.03 (s),
119.73 (s), 119.55 (s), 116.88 (s), 116.49 (s), 113.82 (s),
56.71 (s), 56.05 (s). Elemental analysis; C15H15NO3, calculated
(founded); C, 70.02 (64.04); H, 5.88 (5.83); N, 5.44 (5.28).
Synthesis of 2-((2,5-dimethoxybenzylidene)amino)phenol
(S2)
Aminophenol 1.091 g (0.01 mol) was dissolved gently
in 25 mL of MeOH to complete dissolution of the ma-
terial. To this solution, 1.661 g (0.01 mol) of 3,4-
dimethoxybenzaldehyde solution in 25 mL of MeOH
was slowly added with stirring. The crude product was
filtered and purified by recrystallization from methyl
alcohol, and the vacuum was dried in a desiccator.
IR (KBr, disc, ν cm−1): 3340 (O–H), 3004–2931 (C–H,
aromatic), 2840–2604 (C–H, alifatik), 1618 (C=N), 1514–
1
1419 (C=C, aromatic), 1272 (C–O, aromatic). H NMR
(300 MHz, DMSO) δ 9.44 (s, 1H), 8.49 (s, 1H), 7.52 (d, J =
1.8 Hz, 1H), 7.39 (d, J = 8.3, 1.8 Hz, 1H), 7.15 (dd, J = 8.7 Hz,
2H), 7.06 (d, J = 8.3 Hz, 1H), 6.79 (dd, J = 8.7 Hz, 2H), 3.83
(s, 4H), 3.82 (s, 2H). 13C NMR (75 MHz, DMSO) δ 157.36
(s), 156.33 (s), 151.80 (s), 149.44 (s), 143.42 (s), 129.95 (s),
123.84 (s), 122.71 (s), 116.13 (s), 111.74 (s), 109.58 (s), 56.05
(s), 55.87 (s). Elemental analysis; C15H15NO3, calculated
(founded); C, 70.02 (78.59); H, 5.88 (5.85); N, 5.44 (4.70).
Materials and methods
Materials
The solvents and molecules were purchased from Sigma-
Aldrich. They were used without purification.
Synthesis of 1-(2,4-dimethoxyphenyl)-N-phenylmethanimine
(S3)
Synthesis method
Aniline 0.931 g (0.01 mol) was dissolved gently in 25 mL of
MeOH to complete dissolution of the material. To this solution,
1.661 g (0.01 mol) of 2,4-dimethoxybenzaldehydesolution in
25 mL of MeOH was slowly added with stirring. The crude
product was filtered and purified by recrystallization from
methyl alcohol, and the vacuum was dried in a desiccator.
The synthesis method of Schiff bases is given in supplemen-
tary materials. We show the synthesis reaction scheme in
Fig. 1. The 13C NMR, 1H NMR, and FT-IR spectra of synthe-
sized novel Schiff base compounds are shown in Figs. 1S–4S.

Struct Chem
Fig. 1 The general synthesis reaction of Schiff bases compounds. R1 = OH,
R2 = H, R3 = OCH3, R4 = H, R5 = H, R6 = OCH3, (E)-2-((2,5-
dimethoxybenzylidene)amino)phenol (S1); R1 = H, R2 = OH, R3 = H, R4 =
dimethoxybenzylidene)amino)phenol (S2); R1 = H, R2 = H, R3 = OCH3,
R4 = H, R5 = OH3, R6 = H, (E)-1-(2,4-dimethoxyphenyl)-N-
phenylmethanimine (S3); R1 = H, R2 = OH, R3 = OCH3, R4 = H, R5 = OH3,
R6 = H, (E)-4-((2,4-dimethoxybenzylidene)amino)phenol (S4)
O C H
,
R
= O C H
,
R
= H , ( E ) - 4 - ( ( 3 , 4 -
6
3
5
3
IR (KBr, disc, ν cm−1): 3017–2919 (C–H, aromatic),
2839–2572 (C–H, aliphatic), 1594 (C=N), 1506–1423
(C=C, aromatic), 1299 (C–O–C, aromatic). 1H NMR
(300 MHz, DMSO) δ 9.46 (s, 1H), 8.68 (s, 1H), 7.98
(d, J = 20.0, 8.3 Hz, 1H), 7.16 (t, J = 7.9 Hz, 1H), 6.60
(m, 5H), 3.88 (s, 3H), 3.85 (s, 3H). 13C NMR
(75 MHz, DMSO) δ 164.10 (s), 161.24 (s), 158.54
(s), 154.94 (s), 154.30 (s), 130.32 (s), 128.67 (s),
117.48 (s), 112.95 (s), 112.12 (s), 107.99 (s), 106.95
(s), 98.53 (s), 56.30 (s), 55.99 (s). Elemental analysis;
C15H15NO3, calculated (founded); C, 74.67 (54.70); H,
6.27 (4.09); N, 5.81 (4.69).
Elmer FT-IR Spectrometer. Ultraviolet–visible (UV–vis) ab-
sorption spectra and steady-state fluorescence spectra were
recorded on Perkin Elmer Lambda-35 Spectrophotometer
and Perkin Elmer-LS-55 Fluorescence Spectrometer, respec-
tively The solutions were prepared as 5 × 10−5 M. Ultraviolet–
visible absorption spectra were recorded on a wavelength
range of 200–700 nm, when fluorescence spectra were record-
ed on by choosing excitation wavelength 340 nm for S1,
330 nm for S2, 330 nm for S3, and 340 nm for S4,
respectively.
Electric dipole moment calculations
Lippert–Mataga, Bakhshiev, and Bilot–Kawski methods
Synthesis of 4-((2,4-dimethoxybenzylidene)amino)phenol
(S4)
The dipole moments were determined using the solvatochromic
shifts. These methods are Lippert–Mataga (Eq. (1)) [61, 62],
Bakhshiev (Eq. (2)) [63], and modified Bilot–Kawski (Eq. (3))
[65–70]. The theory of solvent-induced shifts was analyzed
according to the formulas derived by Bilot and Kawski and
rearranged by Chamma and Viallet [71].
4-Aminophenol 0.931 g (0.01 mol) was dissolved gently
in 25 mL of MeOH to complete dissolution of the ma-
terial. To this solution, 1.661 g (0.01 mol) of 2,4-
dimethoxybenzaldehyde solution in 25 mL of MeOH
was slowly added with stirring. The crude product was
filtered and purified by recrystallization from methyl
alcohol, and the vacuum was dried in a desiccator.
IR (KBr, disk, ν cm−1): 3490 (O–H), 3053–2931 (C–
H, aromatic), 2880–2583 (C–H, alifatik), 1609 (C=N),
1513–1448 (C=C, aromatic), 1278 (C–O, aromatic). 1H
NMR (300 MHz, DMSO) δ 9.40 (s, 1H), 8.72 (s, 1H),
7.94 (d, J = 8.4 Hz, 1H), 7.08 (d, J = 8.6 Hz, 2H), 6.78
(d, J = 8.6 Hz, 2H), 6.64 (s, 1H), 6.61 (s, 1H), 3.87 (s,
3H), 3.83 (s, 3H). 13C NMR (75 MHz, DMSO) δ
163.61 (s), 160.86 (s), 156.17 (s), 152.26 (s), 144.22
(s), 128.31 (s), 122.54 (s), 117.95 (s), 116.16 (s),
106.80 (s), 98.53 (s), 56.24 (s), 55.93 (s). Elemental
analysis; C15H15NO3, calculated (founded); C, 70.02
(56.47); H, 70.02 (56.47); N, 5.44 (5.35).
~va−~vf ¼ m1 F1ðε; nÞ þ constant
~va−~vf ¼ m2 F2ðε; nÞ þ constant
ð1Þ
ð2Þ
~va þ ~vf
¼ −m3 F3ðε; nÞ þ constant
ð3Þ
2
Where
ꢀ
ꢁ
2
2 μe−μg
m1 ¼
ð4Þ
hca30
ꢀ
ꢁ
ꢁ
2
2 μe−μg
m2 ¼
m3 ¼
ð5Þ
ð6Þ
hca30
ꢀ
2 μ2e−μ2g
Instruments and measurement methods
hca30
1
The 13C NMR, H NMR, and elemental analysis were done
~va and ~vf are the absorption and fluorescence maxima
wavenumbers (in cm−1), respectively. F1(ε, n) (Lippert −
Mataga Function), F2(ε, n) (Bakshiev Function), and F3(ε,
with using High-Resolution Digital 300 MHz Bruker Biospin
NMR Spectrometer and LECO, CHNS-932 Elemental
Analysis, respectively. FT-IR spectra were taken on a Perkin

Struct Chem
n) (Modified Bilot − Kawski Function) are functions correlated
given by Eqs. (7), (8), and (9), respectively; m1, m2, and m3 are
the slopes found by linear curve fitting as seen in Eqs. (7), (8),
and (9), respectively.
Where mEN is the slope obtained from the linear plot of
T
Stokes shift as indicated in Eq. (15).
~va−~vf ¼ m :ENT þ constant
ð15Þ
ETN
ε−1
n2−1
F1ðε; nÞ ¼
F2ðε; nÞ ¼
−
ð7Þ
ð8Þ
%
2ε þ 1 2n2 þ 1
Quantum chemical calculations
ꢂ
ꢃ
n2−1
2n2 þ 1
ε−1
n2−1
−
n2 þ 1
ε þ 2 n2 þ 2
Quantum chemical calculations are performed to research
as detail to the electronic structure of the investigated
molecule. Energy optimization and frequency calculations
of this molecule have been done by using B3LYP/6-
311G(d,p) [80] method and basis set with Gaussian09W
software [81]. Frequency calculations have controlled to
the question whether the imaginer frequency is observed
or not. Afterwards, Onsager cavity radiuses of these mol-
ecules have been calculated by using B3LYP/6-311G(d,p)
method and basis set. GaussView05 [82] is used for visu-
alization of the results from the output file obtained from
Gaussian09W.
$
ꢄ
ꢅ
2n2 þ 1
ε−1
3ðn4−1Þ
F3ðε; nÞ ¼
−
þ
2
2ðn2 þ 1Þ ε þ 2 n2 þ 2
2ðn2 þ 2Þ
ð9Þ
Here, ε and n are dielectric constant and refractive index of
the solvents. Employing linear curve fitting route for ~va−~vf
À
Á
versus F1(ε, n), ~va−~vf versus F2(ε, n), and ~va þ ~vf =2 versus
F3(ε, n) gives m1, m2, and m3, respectively. If it can be sup-
posed that ground- and excited-state dipole moments are par-
allel, then:
ꢄ
ꢅ
1=2
m3−m2 hca3
Statistical methods
μg ¼
ð10Þ
2
2m2
ꢄ
ꢅ
LSERs have depicted to the specific/nonspecific interac-
tions and intra/inter molecular interactions in electronic
transition mechanisms of solute molecules in the solvent
medium. The LSER approach is preferable because it has
been successfully applied to the positions or intensities of
maximal absorption in UV–visible absorption and fluores-
cence spectra [77, 78]. The Kamlet–Taft solvatochromism
equation is given as
1=2
m3 þ m2 hca3
μe ¼
μe ¼
ð11Þ
ð12Þ
2
2m2
m3 þ m2
m3−m2
μg; ðm3 > m2Þ
Besides, the Reichardt method based on the empirical scale
ET [64, 77, 78] can be used for estimating dipole variation
(Δμ) from the solvatochromic shift. The theoretical basis for
the correlation of the shift with ET has been developed by
Ravi et al. [79].
N
N
ϑmax ¼ C0 þ C1 f ðnÞ þ C2 f ðεÞ þ C3β þ C4α
ð16Þ
"
#
ꢄ
ꢅ ꢄ
ꢅ
3
2
aBB
a0
In here, ϑmax is defined as the maximum absorption
band depending on solvent parameters of the molecule;
f(ε) = (ε − 1)/(ε + 1), f(n) = (n2 − 1)/(n2 + 1), β, and α are
determined as dipolarity-orientation and polarization-
induction functions, hydrogen bonding acceptor ability,
and hydrogen bonding donor ability, respectively. The
C0 coefficient can determine the maximum absorption
band in gaseous phthe ase, and C1, C2, C3, and C4
are coefficients that represent f(n), f(ε), β, and α param-
eter values [72, 73].
∇μ
∇ μB
~va−~vf ¼ 11307:6
ENT þ constant
ð13Þ
Where ΔμB = 9D and ɑB = 6.2 Å are the change in
dipole moment on excitation and Onsager Radius of
reference betaine dye, respectively. Δμ and ɑ0 have
relevant with dipole moment change and Onsager radius
for the solute molecule. The change in dipole moment
Δμ and ɑ0 is the corresponding dipole moment change
and Onsager radius for the solute molecule. The change
in dipole moment Δμ can be determined as:
Another method, Catalan solvatochromism equation, is
given as [75–77].
ϑmax ¼ C5 þ C6SP þ C7SdP þ C8SA þ C9SB
ð17Þ
vffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
u
N
mE Â 81
u
T
u
μe−μg ¼
ð14Þ
ꢀ
ꢁ
t
3
In here, SP defines the solvent polarity, SdP defines solvent
dipolarity, SA defines the acidity of solvent, and SB is the
basicity of solvent. The C5 coefficient can determine the
6:2
11307:6 Â
=
a0

Struct Chem
maximum absorption band in the gaseous phase. C6, C7, C8,
and C9 are coefficients that represent SP, SdP, SA, and SP
parameter values. Dielectric constant, ε, and refractive index,
n, were taken from the literature [78].
rings. The second electronic band displays hypsochromic shifts
in electronic absorption spectra with increasing solvent polarity.
Fluorescence spectra of S1 in different solvents are given in
Fig. 2. As can be seen in Table 1 and Fig. 2, fluorescence
spectra of S1 indicate three electronic transition bands in cy-
clohexane and two electronic transition bands in diethyl ether,
n-butyl acetate, DCM, and acetonitrile and one electronic tran-
sition band in other solvents. The first band in the fluorescence
spectra can be attributed to electronic transition of conjugation
between –N=CH– and benzene ring. The second band in fluo-
rescence spectra can be originated from the electron move-
ments in the –N=CH– group. Fluorescence spectra wave-
length λPL(nm), frequency ν (cm−1), and Stokes shift values
of S1 are listed in Table 1. Stokes shift does not regularly
change with solvent polarity for S1.
Result and discussion
Electronic absorption and fluorescence spectra
The electronic spectral data of S1, S2, S3, and S4 in different
non-polar, polar aprotic, and polar protic solvents with various
polarities have been tabulated in Tables 1, 2, 3, and 4. As seen
from Table 1 and Fig. 2, electronic absorption spectra of S1
molecule exhibit two main bands centered in the regions of
269–291 nm and 358.17–379.22 nm, respectively. These first
electronic transition bands are born out from conjugations of
aromatic rings, while second electronic transition bands are
born out from delocalization between –N=CH– and aromatic
The absorbance spectra of S2 in different solvents are given in
Fig. 3. The absorbance spectra wavelength and wavenumber for
S2 molecule are shown in Table 2. As can be seen in Table 2 and
Fig. 4, electronic absorption spectra of S2 derivatives exhibit four
Table 1 The absorption and fluorescence wavenumber data in different solvent medium of S1 molecule
1
2
2
1
1
2
3
4
1
Solvents
λabs
λabs
νabs
λPL
νPL
λPL
λPL
λPL
νabs2-νPL
n-Pentane
n-Hexane
Cyclohexane
1,4-Dioxane
Benzene
278.78
290.94
278.78
276.27
–
374.58
371.57
375.45
374.20
379.22
377.96
–
26,696.79
26,913.02
26,634.38
26,723.63
26,370.17
26,457.66
–
448.38
383.71
382.10
418.20
380.49
382.69
382.69
410.19
437.25
426.72
387.07
430.08
418.38
411.80
411.36
411.36
448.22
451.44
450.71
414.87
453.20
651.13
398.63
461.39
426.72
389.85
479.53
422.04
22,302.51
26,061.35
26,171.16
23,912
–
–
–
4394.28
851.67
–
–
–
408.58
430.08
456.42
463.22
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
2811.63
88.27
26,281.9
–
Toluene
–
26,130.81
26,130.81
24,378.95
22,870.21
23,434.57
25,835.12
23,251.49
23,901.72
24,283.63
24,309.61
24,309.61
22,310.47
22,151.34
22,187.22
24,103.94
22,065.31
15,357.92
25,085.92
21,673.64
23,434.57
25,650.89
20,853.75
23,694.44
–
326.85
o-Xylene
–
–
–
Diethyl ether
Chloroform
Ethyl acetate
n-Butyl acetate
THF
295.71
278.78
288.81
290.06
–
369.18
376.71
370.44
372.95
368.06
375.08
365.17
362.41
359.53
362.41
358.15
359.53
366.68
363.79
356.77
370.94
360.91
366.68
368.06
358.15
365.17
27,086.69
26,545.73
26,995.01
26,813.48
27,169.75
26,661.09
27,384.32
27,592.77
27,814.11
27,592.77
27,921.23
27,814.11
27,271.95
27,488.15
28,029.17
26,958.51
27,707.81
27,271.95
27,169.75
27,921.23
27,384.32
430.08
2707.74
3675.52
3560.44
978.36
–
–
411.80
–
3918.26
2759.37
3100.69
3283.16
3504.5
DCM
290.19
290.19
274.51
271.76
284.42
284.42
258.97
–
436.67
1-Octanol
1-Heptanol
1-Hexanol
1-Butanol
iso-Butanol
2-Propanol
Acetone
–
–
–
–
5282.3
–
5769.89
5626.89
3168.01
5422.84
12,671.25
1872.59
6034.17
3837.38
1518.86
7067.48
3689.88
–
–
1-Propanol
Ethanol
268.87
283.04
–
–
–
Benzonitrile
Methanol
DMF
–
270.25
287.30
290.19
288.68
–
–
–
Acetonitrile
Ethylene glycol
DMSO
436.67
–
–

Struct Chem
Table 2 The absorption and
fluorescence wavenumber data in
different solvent medium of S2
molecule
1
2
3
3
4
1
1
1
Solvents
λabs
λabs
λabs
νabs
λabs
λPL
νpl
νabs3-νPL
n-Pentane
n-Hexane
Cyclohexane
1,4-Dioxane
Benzene
–
–
–
–
–
–
–
–
274.40 328.43 30,447.89
–
379.61 26,342.83 4105.06
272.13 312.01 32,050.25 341.60 359.26 27,834.99 4215.26
273.51 313.01 31,947.86 335.71 359.43 27,821.83 4126.03
279.53 332.70 30,057.11
326.67 335.45 29,810.7
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
399.95 25,003.13 5053.98
407.26 24,554.34 5256.36
376.69 26,547.03 3119.52
357.67 27,958.73 1187.29
Toluene
–
–
337.08 29,666.55
343.10 29,146.02
o-Xylene
Diethyl ether
Chloroform
Ethyl acetate
n-Butyl acetate
THF
282.41 334.20 29,922.2
405.51 24,660.3
5261.9
266.11 273.92 337.08 29,666.55
409.16 24,440.32 5226.23
390.73 25,593.12 4463.99
388.83 25,718.18 4204.02
407.70 24,527.84 5006.4
417.21 23,968.74 5953.46
413.26 24,197.84 5076.16
–
–
–
–
–
–
–
–
–
–
279.53 332.70 30,057.11
280.91 334.20 29,922.2
279.53 338.59 29,534.24
282.41 334.20 29,922.2
282.41 341.60 29,274
273.51 341.60 29,274
279.53 341.60 29,274
280.91 340.09 29,403.98
280.91 341.60 29,274
280.91 337.08 29,666.55
DCM
1-Octanol
1-Heptanol
1-Hexanol
1-Butanol
iso-Butanol
2-Propanol
Acetone
405.51 24,660.3
401.70 24,894.2
405.51 24,660.3
4613.7
4379.8
4743.68
394.39 25,355.61 3918.39
410.92 24,335.64 5330.91
414.72 24,112.65 5944.46
379.61 26,342.83 3191.41
403.02 24,812.66 4721.58
394.39 25,355.61 4310.94
405.36 24,669.43 4734.55
418.38 23,901.72 5908.98
418.38 23,901.72 6167.14
398.19 25,113.64 4322.37
227.74 280.91 332.70 30,057.11
1-Propanol
Ethanol
–
–
–
280.91 338.59 29,534.24
278.03 338.59 29,534.24
316.39 337.08 29,666.55
Benzonitrile
Methanol
DMF
224.73 282.41 340.09 29,403.98
281.66 335.45 29,810.7
–
Acetonitrile
227.74 281.66 332.57 30,068.86
227.74 281.66 339.72 29,436.01
Ethylene
glycol
DMSO
–
–
334.48 29,897.15
–
398.05 25,122.47 4774.68
strong bands centered in the regions of 224–227 nm, 273–
282 nm, 312–316 nm, and 328–341 nm, respectively. The first
and second band in the fluorescence spectra can be originated to
conjugation on benzene rings. The third band in the fluorescence
spectra can be attributed to electronic transition due to delocali-
zation between –N=CH– and benzene rings. The forth band
corresponds to electronic transitions at –N=CH– group.
As can be seen in Table 2 and Fig. 3 in the fluorescence
spectra of S2, it exhibits one band centered in the region of
357–418 nm. This band can be attributed to electronic emis-
sion transition that represents conjugation between –N=CH–
and the benzene ring. As the polarity of the solvent increases,
the wavelength increases irregularly and displays a
bathochromic effect.
340 nm, respectively. The first and second band in the
absorbance spectra can be attributed to electronic transition
due to conjugation in benzene rings and conjugation be-
tween –N=CH– and benzene rings. The third band is orig-
inated from electronic transitions in –N=CH– group. As the
polarity of the solvent increases, the wavelength decreases;
in other words, it displays hypsochromic effect.
The fluorescence spectra of S3 in different solvents are
given in Table 3 and Fig. 4. As can be seen in Table 3 and
Fig. 4, the fluorescence spectra of S3 exhibit one band. This
band can represent the florescence transitions that originated
from conjugation between benzene ring and –N=CH– group.
As the polarity of the solvent increases, the wavelength de-
creases irregularly and displays hypsochromic effect.
Absorbance spectra of S3 in different solvents are given
in Fig. 4. The absorbance spectra wavelength wavenumbers
for the S3 molecule are shown in Table 3. As can be seen
in Table 3 and Fig. 4, absorbance spectra electronic transi-
tions of S3 derivatives exhibit three strong bands centered
in the regions of 231–240 nm, 267–280 nm, and 319–
The absorbance spectra of S4 in different solvents are given
in Fig. 5. The absorbance spectra wavelength and molar ab-
sorptivity values observed in for S4 molecule are shown in
Table 4. As can be seen in Table 4 and Fig. 5, electronic
absorption spectra of S4 derivatives exhibit four strong bands
centered in the regions of 223–232 nm, 264–280 nm, 305–

Struct Chem
Table 3 The absorption and
fluorescence wavenumber data in
different solvent medium of S3
molecule
1
2
3
3
4
Solvents
λabs
λabs
λabs
νabs
λabs
λPL
νPL
νabs3-νPL
n-Pentane
n-Hexane
Cyclohexane
1,4-Dioxane
Benzene
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
267.75 312.15 32,035.88 334.90 422.04 23,694.44 8341.44
268.19 300.44 33,284.52 369.52 27,062.13 6222.39
269.72 302.27 33,083.01 340.75 369.52 27,062.13 6020.88
274.18 329.04 30,391.44
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
403.02 24,812.66 5578.78
434.03 23,039.88 6918.18
374.35 26,712.97 4467.85
374.35 26,712.97 2409.29
405.36 24,669.43 5939.69
417.21 23,968.74 6200.81
419.70 23,826.54 7468.45
395.85 25,262.09 5415.58
414.87 24,103.94 6065.61
419.70 23,826.54 6673.35
414.87 24,103.94 5959.49
411.80 24,283.63 6114.28
405.36 24,669.43 5823.02
372.30 26,860.06 3269.5
399.95 25,003.13 5489.32
410.19 24,378.95 5906.64
414.26 24,139.43 4889.83
414.87 24,103.94 6065.61
410.19 24,378.95 6120.94
386.20 25,893.32 3434.77
412.53 24,240.66 5975.38
419.70 23,826.54 6343.01
411.80 24,283.63 6114.28
403.02 24,812.66 5553.86
–
–
333.80 29,958.06
320.71 31,180.82
Toluene
o-Xylene
Diethyl ether
Chloroform
Ethyl acetate
n-Butyl acetate
THF
315.95 343.38 29,122.26
276.53 326.70 30,609.12
278.94 331.46 30,169.55
274.18 319.54 31,294.99
276.60 325.97 30,677.67
278.94 331.46 30,169.55
272.94 327.87 30,499.89
277.77 332.63 30,063.43
273.67 328.97 30,397.91
268.77 327.95 30,492.45
DCM
1-Octanol
1-Heptanol
1-Hexanol
1-Butanol
iso-Butanol
2-Propanol
Acetone
240.10 279.60 331.90 30,129.56
–
–
–
–
–
–
–
–
270.75 327.95 30,492.45
277.02 330.19 30,285.59
–
344.48 29,029.26
1-Propanol
Ethanol
277.77 331.46 30,169.55
278.94 327.87 30,499.89
Benzonitrile
Methanol
DMF
–
340.97 29,328.09
277.62 330.95 30,216.04
331.46 30,169.55
–
Acetonitrile
231.25 277.62 328.97 30,397.91
Ethylene
glycol
–
280.28 329.31 30,366.52
DMSO
–
274.18 319.54 31,294.99
–
398.19 25,113.64 6181.35
315 nm, and 337–350 nm, respectively. The first transition
band is just observed in polar protic solvents. The second
transition band can represent the electronic transitions that
originated from conjugation in the benzene ring. The third
transition band is originated from conjugation between ben-
zene rings and –N=CH– group.
The fluorescence spectra of S4 in different solvents are
given in Table 4 and Fig. 5. As can be seen in Table 4 and
Fig. 5 in the fluorescence spectra of S4, one band was ob-
served. This band can represent the fluorescence transitions
that originated from conjugation in –N=CH– group.
Statistical parameters derived from maximum absorption and
emission spectra are listed in Tables 5 and 6, respectively.
Figures 5S, 9S, 13S, and 17S show the correlation graph
between the frequencies obtained experimentally using the
Kamlet–Taft parameters for absorbance spectra S1, S2, S3,
and S4 (R2 = 0.887 (S1), R2 = 0.814 (S2), R2 = 0.744 (S3),
and R2 = 0.627 (S4)).
When the Kamlet–Taft parameters obtained by using the
absorbance spectra of molecules are examined, it can be seen
that the greatest contribution to absorbance spectra of S1, S2,
S3, and S4 molecules is from the diffraction function. The
Kamlet–Taft parameter calculations for maximum electronic
absorption transition of S1, S2, S3, and S4 molecules are
performed by using 27, 23, 23, and 22 solvents, respectively.
As seen from Table 5, C1 is negative for all of the mole-
cules and C2 is negative for S3 and S4. It is found that
│C1│ > │C2│for studied compounds. C1 is a measurement
of the orientation-induction interaction (refractive index func-
tion), while C2 describes the dispersion-polarization
Solvatochromism
It is well known that solvent induces the spectral shift and
related electronic transitions in the molecules. These spectral
shifts are analyzed by using linear salvation energy relation-
ships described with Kamlet–Taft and Catalan methods.

Struct Chem
Table 4 The absorption and
fluorescence wavenumber data in
different solvent medium of S4
molecule
1
2
3
4
4
Solvents
λabs
λabs
λabs
λabs
νabs
λPL
νPL
ν
abs4-νPL
n-Pentane
n-Hexane
Cyclohexane
1,4-Dioxane
Benzene
–
–
–
–
–
–
–
–
–
–
–
–
–
–
264.98 305.61
266.74 303.98
266.74 307.37
–
–
–
–
–
–
405.95 24,633.58
382.25 26,160.89
382.25 26,160.89
–
–
–
278.53
–
344.48 29,029.26 409.90 24,396.19 4633.07
–
315.77 339.47 29,457.68 386.20 25,893.32 3564.36
314.14 344.48 29,029.26 409.90 24,396.19 4633.07
Toluene
–
o-Xylene
Diethyl ether
Chloroform
Ethyl acetate
n-Butyl acetate
THF
–
–
–
–
337.71 29,611.2
381.52 26,210.95 3400.25
276.87
278.53
341.10 29,316.92 409.90 24,396.19 4920.73
342.85 29,167.27 425.69 23,491.27 5676
275.14 314.14 339.48 29,456.82 429.64 23,275.3
6181.52
386.20 25,893.32 2988.38
344.48 29,029.26 386.20 25,893.32 3135.94
337.71 29,611.2 424.38 23,563.79 6047.41
344.48 29,029.26 417.21 23,968.74 5060.52
346.24 28,881.7 410.19 24,378.95 4502.75
349.62 28,602.48 410.19 24,378.95 4223.53
346.24 28,881.7 388.10 25,766.56 3115.14
339.47 29,457.68 400.53 24,966.92 4490.76
341.10 29,316.92 384.15 26,031.5 3285.42
278.53
279.03
276.90
281.16
–
346.24 28,881.7
–
DCM
–
1-Octanol
1-Heptanol
1-Hexanol
1-Butanol
iso-Butanol
2-Propanol
Acetone
–
223.85 275.14
224.36 278.53
–
–
–
–
–
–
–
278.53
276.90
278.53
–
–
–
–
–
353.01 28,327.81 417.21 23,968.74 4359.07
344.48 29,029.26 425.69 23,491.27 5537.99
341.10 29,316.92 412.53 24,240.66 5076.26
1-Propanol
Ethanol
278.53
–
227.74 276.90
–
Benzonitrile
Methanol
DMF
–
–
317.90
–
–
381.52 26,210.95
–
232.89 278.52
–
–
–
–
341.10 29,316.92 386.20 25,893.32 3423.6
344.48 29,029.26 386.02 25,905.39 3123.87
341.10 29,316.92 386.20 25,893.32 3423.6
–
–
–
Acetonitrile
273.51
Ethylene
glycol
232.89 280.29
337.71 29,611.2
398.19 25,113.64 4497.56
DMSO
–
279.03
–
350.63 28,520.09 413.85 24,163.34 4357.09
(dielectric function). The values in Table 5 indicate that elec-
tronic transitions exhibit bathochromic effect (red shift) de-
pending on dispersion-polarization force and the contribution
of the dispersion-polarization force is greater than those of the
orientation-induction force.
The Kamlet–Taft parameter calculations for maximum
electronic emission transition of S1, S2, S3, and S4 molecules
are performed by using 23, 24, 22, and 16 solvents, respec-
tively. R2 and R values given in Table 6 indicate acceptability
of statistical parameters of the investigated molecules.
│C3│value is bigger than │C4│ value for S1 and S4 mol-
ecules. Thus, electronic transitions of S1 and S4 molecules
have occurred by the larger effect of H-bond acceptor ability
in accordance with H-bond donor ability. However, H-bond
donor ability in S2 and S3 molecules has a larger effect on
electronic transition than H-bond acceptor ability.
Figures 6S, 10S, 14S, and 18S show the correlation graph
between the frequencies obtained experimentally using the
Kamlet–Taft parameters for fluorescence spectra of S1, S2, S3,
and S4 (R2 = 0.738, R2 = 0.753, R2 = 0.837, and R2 = 0.723).
When the Kamlet–Taft parameters obtained by using the
fluorescence spectra of molecules are examined, it can be seen
that the greatest contribution to fluorescence spectra of S1, S2,
S3, and S4 molecules is from the diffraction function (disper-
sion-induction interaction).
It can be said from Table 5 that absolute C1 values derived
from Kamlet–Taft model are obtained as bigger than C2 values.
Thus, electronic emission transitions are found more effective
on dispersion-polarization interactions in comparison with
orientation-induction interactions. Positive C1 values show that
electronic transitions in all molecules exhibit hypsochromic ef-
fect (blue shift) by the effect of dispersion-polarization forces. It
is also observed that │C3│ > │C4│except for S1. Thus, the
contribution of H-bond acceptor ability to the spectral shift in
the electronic emission transitions in S2, S3, and S4 molecules
is more effective than the contribution of H-bond donor ability.
However, the inverse case is true for S1.
C3 value is negative for S2 and S4 molecules, and this
value is positive for S1 and S3 molecules. We can say that
electronic emission spectra of S2 and S4 molecules exhibit red

Struct Chem
Fig. 2 The absorbance spectra and flourescence spectra of S1 molecule in the various solvents versus the wavelength (excitation wavelength is 340 nm)
shifts depending on H-bond acceptor ability of using solvents,
while electronic emission spectra of S1 and S3 exhibit blue
shifts depending on H-bond acceptor ability of solvents.
Figures 7S, 11S, 15S, and 19S show the correlation graph
between the frequencies obtained experimentally using the
Catalan parameters for absorbance spectra of S1, S2, S3, and
S4 (R2 = 0.888 (S1), R2 = 0.715 (S2), R2 = 0.766 (S3), and
R2 = 0.729 (S4)).
When the Catalan parameters obtained by using the absor-
bance spectra of molecules are examined, it can be seen that
the greatest contribution to S1, S2, S3, and S4 molecules is
from the solvent polarity (SP). The Catalan parameter calcu-
lations for maximum electronic absorption transition of S1
molecules have been carried out by using 28 solvents, while
calculations for maximum electronic absorption transition of
S2, S3, and S4 molecules are performed in 24, 25, and 26
Fig. 3 The absorbance spectra and flourescence spectra of S2 molecule in the various solvents versus the wavelength (excitation wavelength is 330 nm)

Struct Chem
Fig. 4 The absorbance spectra and flourescence spectra of S3 molecule in the various solvents versus the wavelength (excitation wavelength is 330 nm)
solvents, respectively. According to MLRA results, polarity/
polarizability of the solvent, C6 coefficients are obtained as
negative for all investigated molecules. This demonstrates that
electronic absorption band maxima of S1, S2, S3, and S4
molecules exhibit bathochromic shift with increasing of
polarity/polarizability of solvents. The coefficients C8 and
C9 describe the contribution of solvent acidity (SA) and sol-
vent basicity (SB) to the electronic absorption spectral shift,
respectively. Negatively signed C9 suggests that basicity of the
solvent causes the absorption band shifts to lower energies
with the increasing of solvent basicity for S2, S3, and S4.
An inverse case for positively signed C9 can be considered
for S1 molecule.
According to the Catalan solvatochromic model, we have
observed that │C8│ > │C9│ for S1 and S2, whereas
│C9│ > │C8│ for S3 an S4. We can say that acidity of solvent
is relatively more effective than basicity of solvent for S1 and S2.
The inverse case can be considered for S3 and S4 molecules.
Fig. 5 The absorbance spectra and flourescence spectra of S4 molecule in the various solvents versus the wavelength (excitation wavelength is 340 nm)

Struct Chem
Table 5 LSER’s results calculated with using Kamlet–Taft and Catalan parameters for absorption maximum wavenumber of S1, S2, S3, and S4
molecules
Molecules C0
C1
C2
C3
R
R2
F
P
N
Extracted solvents
Kamlet–Taft solvatochromism (absorbance spectra)
S1
S2
26,590.92 −88.82
29,853.31 120.04
1031.87 399.32
−85.63 −528.45
0.920 0.847 42.29 0.000 27
–
0.85 0.723 15.664 0.000 22 n-Pentane, n-Hexane, Toluene, o-Xylene,
Benzonitrile, Acetonitrile
S3
S4
32,215.11 −2453.96 −744.70 11.80
31,708.18 −3091.57 −1518.47 91.63
0.849 0.721 17.201 0.000 24 o-Xylene, 1-Octanol, Acetone, DMSO
0.862 0.743 20.277 0.000 25 Ethyl acetate, Benzonitrile, Ethylene glycol
Molecules C4
C5
C6
C7
C8
R
R2
F
P
N
Extracted solvents
Catalan solvatochromism (absorbance spectra)
S1
S2
27,484.05 −1482.01 396.12
30,960.25 −1868.35 512.80
1039.58 717.19
0.943 0.888 43.819 0.000 28
–
−1250.54 −257.93 0.845 0.715 11.897 0.000 24 n-Pentane, n-Hexane, 1,4-Dioxane,
Ethylene glycol
S3
S4
34,964.56 −3685.91 −2207.07 927.25
36,160.51 −6689.20 −1904.59 1423.26 −2222.73 0.854 0.729 14.098 0.000 26 Ethyl acetate, Benzonitrile
−1282.07 0.875 0.766 16.400 0.000 25 Benzene, Toluene, DMSO
Figures 8S, 12S, 16S, and 20S show the correlation
the greatest contribution to S1 is from the solvent polar-
ity (SP), to S2 and S3 from the solvent dipolarity (SdP),
and to S4 from the solvent acidity (SA). The Catalan
parameter calculations for maximum electronic emission
transition of S1 molecule have been carried out by using
25 solvents, while calculations for maximum electronic
absorption transitions of S2, S3, and S4 molecules are
graph between the frequencies obtained experimentally
using the Catalan parameters for fluorescence spectra
S1, S2, S3, and S4 (R2 = 0.759 (S1), R2 = 0.712 (S2),
R2 = 0.736 (S3), and R2 = 0.764 (S4)). When the
Catalan parameters obtained by using the fluorescence
spectra of molecules are examined, it can be seen that
Table 6 LSER’s results calculated with using Kamlet–Taft and Catalan parameters for fluorescence maximum wavenumber of S1, S2, S3, and S4
molecules
Molecules C0
C1
C2
C3
R
R2
F
P
N
Extracted solvents
Kamlet–Taft solvatochromism (emission spectra)
S1
S2
S3
S4
26,611.75 −1852.31 −1261.67 −2358.82
27,299.27 −3769.73 −1036.83 −59.93
26,885.88 −223.58 −4075.86 1186.74
26,133.35 1363.98 −2790.03 284.13
0.846 0.715 15.066 0.000 22 n-Pentane, 1,4-Dioxane, Chloroform, Ethyl
acetate, THF, Ethanol
0.861 0.741 17.172 0.000 22 n-Pentane, o-Xylene, 1-Propanol,
Benzonitrile, Ethylene glycol, DMSO
0.862 0.743 16.401 0.000 21 n-Pentane, Benzene, Chloroform, Ethyl
acetate, DCM, 1-Butanol, DMSO
0.839 0.705 7.156 0.009 13 n-Pentane, 1,4-Dioxane, Benzene, Toluene,
Chloroform, Ethyl acetate,
DCM,1-Octanol, 1-Butanol, DMF,
DMSO, 2-Propanol, Acetone, 1-Propanol,
Benzonitrile
Molecules C4
C5
C6
C7
C8
R
R2
F
P
N
Extracted solvents
Catalan solvatochromism (emission spectra)
S1
S2
22,851.66 4751.70 −3109.85 −3363.18 69.28
0.871 0.759 15.761 0.000 25 n-Pentane, Ethanol, Acetonitrile
27,435.57 −26.29
−3045.62 1464.24 −1486.48 0.844 0.712 11.722 0.000 24 Benzene,1-Propanol, Ethylene glycol,
DMSO
S3
S4
27,817.55 −1202.95 −2768.37 1382.50 −1551.83 0.858 0.736 12.529 0.000 23 n-Pentane, Benzene, 1-Butanol,
Benzonitrile, DMSO
23,481.26 3900.03 −2832.92 −4785.85 1138.42 0.874 0.764 7.273 0.007 14 n-Pentane, Benzene, Toluene, Chloroform,
Ethyl acetate, 1-Butanol, iso-Butanol,
2-Propanol, Ethanol, Benzonitrile,
Methanol, DMF, Acetonitrile, Ethyl
acetate, Glycerol

Struct Chem
Table 7 Spectral treatment of the Lippert–Mataga, Bakhshiev, modified Bilot–Kawski, and Reichardt correlation of investigated compounds
Equation
Slope
Intercept Cor. (R2) Solvent used in correlation
N
S1
Lippert–Mataga
m1 = 18,320
m2 = 6743.6
409.1
0.9841
0.9992
0.8522
0.5865
n-Hexane, Cyclohexane, Benzene, Toluene, Ethyl acetate, THF, 1-Butanol,
iso-Butanol, 2-Propanol, 1-Propanol, Methanol
Benzene, Toluene, Diethyl ether, Ethyl acetate, THF, 1-Butanol, 1-Propanol,
Methanol
DCM, 1-Butanol, iso-Butanol, 2-Propanol, 1-Propanol, Methanol,
Ethylene glycol
n-Hexane, Cyclohexane, Benzene, Toluene, n-Butyl acetate, DCM, 1-butanol,
iso-Butanol, 2-Propanol, Acetone, 1-Propanol, Benzonitrile, Methanol, DMF,
Ethylene glycol, DMSO
11
8
Bakhshiev
216.27
Modified
Bilot–Kawski
Reichardt
m3 = −6897.7 29,349
7
mR = 216.78
59.693
16
S2
Lippert–Mataga
m1 = 15,536
m2 = 5664.5
1148.7
1272.7
0.9166
n-Hexane, o-Xylene, Ethyl acetate, n-Butyl acetate, THF, 1-Heptanol, 1-Hexanol, 15
1-Octanol, 1-Butanol, 2-Propanol, Acetone, Benzonitrile, DMF, Acetonitrile,
DMSO
Bakhshiev
0.9713
0.9061
n-Hexane, o-Xylene, Ethyl acetate, n-Butyl acetate,1-Octanol,1-Heptanol,
2-Propanol, Acetone, DMF, Acetonitrile
10
Modified
Bilot–Kawski
m3 = −5949.8 30,621
Cyclohexane, o-Xylene, Ethyl acetate, n-Butyl acetate, THF, DCM, 1-Octanol,
1-Heptanol,
10
1-Hexanol, Acetone
Reichardt
mR = 10,753
1989.2
0.91
n-Hexane, Cyclohexane, Toluene, Chloroform, Ethyl acetate, n-Butyl acetate,
THF, DCM, Acetone, DMF, Acetonitrile
11
S3
Lippert–Mataga
m1 = 13,553
m2 = 4612.4
2181
0.9198
0.9354
0.9126
0.9609
o-Xylene, 1-Hexaneol, iso-Butanol, 2-Propanol, 1-Propanol, Ethanol, Methanol,
DMF, Acetonitrile, Ethylene glycol DMSO
o-Xylene, 1-Hexanol, iso-Butanol, 2-Propanol, 1-Propanol, Ethanol, Methanol,
DMF, Acetonitrile, Ethylene glycol, DMSO
n-Hexane, Cyclohexane, Toluene, Ethyl acetate, n-Butyl acetate, THF, DCM,
1-Octanol, 1-Heptanol, 2-Propanol, Acetone, 1-Propanol, Methanol
Toluene,1-Octanol,1-Heptanol, 1-Hexanol, 2-Propanol, 1-Propanol, Ethanol
11
11
13
7
Bakhshiev
2231.3
Modified
Bilot–Kawski
Reichardt
m3 = −7874.6 31,960
mR = 3107.5
4198.9
S4
Lippert–Mataga
Bakhshiev
m1 = 8514.5
m2 = 1155.9
3252.5
3476.1
0.9737
0.9425
0.9388
o-Xylene, Diethyl ether, 1-Octanol, 1-Propanol, Benzonitrile
Benzene, o-Xylene, 1-Hexanol, iso-Butanol, Acetone, Ethylene glycol, DMSO
n-Pentane, n-Hexane, Cyclohexane, 1,4-Dioxane, Toluene
5
7
5
Modified
m3 = −6730.2 30,826
Bilot–Kawski
Reichardt
mR = 5486.7 1829.4
0.9053
n-Butyl Acetate, THF,1-Octanol, 1-Heptanol, iso-Butanol, 1-Propanol
6
performed in 24, 23, and 14 solvents, respectively.
According to MLRA results, polarity/polarizability of
the solvent, C6 coefficients are obtained as negative for
S2 and S3 molecules and as positive for S1 and S4
(Table 6). This demonstrates that electronic absorption
band maxima of S2 and S3 shift to lower energy
Table 8 Onsager radius, ground-state (μg) and excited-state (μe) dipole moments (in Debye)
ꢀ ꢁ
b
μe
μg
a
L − M
B
M − B − K
R
Molecule
a0
μg
μe
μe
μe
μe
μg (D)
Theo.
(Å)
S1
S2
S3
S4
5.18
5.20
5.16
5.36
0.11
0.22
2.81
0.037
3.19
1.97
1.89
1.061
6.79
6.39
5.07
0.011
0.024
0.261
0.706
4.48
4.34
3.64
4.00
15.00
16.46
11.48
9.14
9.14
10.77
4.255
10.77
10.18
1D = 3.33564 × 10−30 cm = 10−18 esu.cm
a Calculated according to Eq. (10)
b Calculated according to Eq. (12)
L-M, Lippert–Mataga method; B, Bakhshiev method; M-B-K, modified Bilot–Kawski method; R, Reichardt method
a0 (Å) and μg (D) Theo. in gaseous phase is calculation with DFT (B3LYP)/6-311G(d, p) level of theory

Struct Chem
Fig. 6 HOMO, LUMO, MEP,
and SAS shape of S1 molecule
-4.47x10-2
4.47x10-2
E
LUMO=-1.862 eV
ΔE=3.704 eV
EHOMO=-5.556 eV
exposing a bathochromic effect. However, polarity/
polarizability of the solvent gives rise to a hypsochromic
effect on these spectral shifts of S1 and S4.
According to the Catalan solvatochromic model, we have
observed that │C8│ > │C9│ for S1 and S4, whereas
│C9│ > │C8│ for S2 and S3. We can say that acidity of sol-
vent is relatively more effective on electronic transitions than
basicity of solvent for S1 and S4. We can say also that basicity
of solvent is relatively more effective on electronic transitions
than acidity of solvent for S2 and S3 (Table 6).
Fig. 7 HOMO, LUMO, MEP,
and SAS shape of S2 molecule
6.162x10-2
-6.162x10-2
ELUMO=-1.449 eV
ΔE=3.981 eV
EHOMO=-5.430 eV

Struct Chem
Fig. 8 HOMO, LUMO, MEP,
and SAS shape of S3 molecule
-6.059x10-2
6.059x10-2
ELUMO=-1.449 eV
ΔE=3.981 eV
EHOMO=-5.653 eV
Electrical dipole moments
B3LYP/6-311G(d,p) method. Onsager cavity radius and di-
pole moments (Debye) calculated for investigated molecules
at the ground- and excited-states are shown in Table 7.
Excited-state and ground-state dipole moments of investi-
gated molecules were calculated by Lippert–Mataga,
Onsager cavity radius values are ao=5.18A0, ao=
5.20A0,ao = 5.16 A0, and ao = 5.36 A0 for S1, S2, S3, and S4,
respectively, and these values are computed via using DFT-
Fig. 9 HOMO, LUMO, MEP,
and SAS shape of S4 molecule
-6.162x10-2
6.162x10-2
ELUMO=-1.345 eV
ΔE=3.972 eV
ELUMO=-5.317 eV

Struct Chem
Bakhshiev, and modified Bilot–Kawski methods. The results
obtained in the calculations are as stated: In the ground-state,
dipole moments for S1, S2, S3, and S4 are μg = 0.11 D, μg =
0.22 D, μg = 2.81 D, and μg = 0.037 D, respectively. In the
excited-state, the dipole moments calculated by Lippert–
Mataga method for S1, S2, S3, and S4 were found as μe(L −
Conclusions
In this study,
&
&
&
We have synthesized and characterized new Schiff base
derivatives.
M) = 3.19 D, μe(L − M) = 15 D,μe(L − M)=16.46 D, and μe(L − M)
=
These compounds have been commented in view of ab-
sorption and fluorescence electronic transitions.
We have investigated the solvent effect on the electronic
absorption bands for π → π* and n → π* electronic
transitions.
11.48, respectively. According to Bakhshiev method, excited-
state electric dipole moment was found as μe(B) = 1.97 D for
S1, μe(B) = 9.14 for S2, μe(B) = 10.77 D for S3, and μe(B)
4.255 D for S4 molecule.
=
In the excited-state, the dipole moments calculated by mod-
ified Bilot-Kawski methods for S1, S2, S3, and S4 are μe(M − B
− K) = 1.89 D, μe(M − B − K) = 9.14 D, μe(M − B − K)=10.77 D, and
μe(M − B − K) = 10.18 D, respectively. Furthermore, the dipole
moments calculated by the Reichardt method for S1, S2, S3,
and S4 in the excited-state are μe(R)=1.061 D, μe(R) = 6.79 D,
μe(R) = 6.39 D, and μe(R) = 5.07 D, respectively. The correla-
tion figures of the Lippert–Mataga, modified Bilot-Kawski,
and Reichardt correlation spectral treatment of investigated
molecules are shown in Table 8. For all cases, S1 has a smaller
dipole moment in the excited-state. As seen in the table, the
ratio of the excited-state dipole moments to the ground-state
dipole moments is too great for all investigated molecules. So,
we can say that charge irregularity is excessive in investigated
molecules.
&
&
Solvent effect of Schiff base derivatives has been analyzed
by Kamlet–Taft and Catalan approaches.
We have calculated the ground-state electric dipole mo-
ment and excited-state electric dipole moment by using
Lippert–Mataga, Bakhshiev, Kawski–Chamma–Viallet,
and Reichardt solvatochromic shift methods.
The excited-state dipole moment of G1, G2, and G3 is
found to be larger than ground-state dipole moment by
all of the methods.
MEP, HOMO, LUMO, and SAS have been investigated
theoretically.
Excited- and ground-state charge distributions of the S4
molecule are found to be bigger than the other molecules.
&
&
&
Acknowledgements The authors greatly acknowledge the support of
Bitlis Eren University, Scientific and Technological Application and
Research Center. The authors greatly thank Bitlis Eren University for
supporting this study by Gaussian 09 W and GaussView 5.0 software.
HOMO, LUMO, ΔE (ELUMO-EHOMO), MEP, and SAS shape
Funding information This work was financially supported by Bitlis Eren
University Research Foundation. Project number: BEBAP-2014.05.
HOMO, LUMO, ΔE (ELUMO-EHOMO), MEP, and SAS shapes
of investigated new Schiff bases molecules have been calcu-
lated by using DFT/B3LYP/6-311G(d,p) method and basis set
in the gas phase and drawn to Figs. 6, 7, 8, and 9, respectively.
The MEP shape shows to attemptable point interactions as
electronic in the molecule. Thus, inasmuch as MEP figures,
OH substituent of S1 molecule is acceptor site. The focus of
having oxygen substituent in other molecules is electrophilic
properties. As seen from Figs. 6, 7, 8, and 9, the blue color is
methyl and hydrogen moiety of benzene rings, which is elec-
tropositive region. From MEP, S2 and S4 molecules have the
highest electronegative and electropositive value. These re-
gions can occur to electron transfer between solute with sol-
vent molecule.
As seen from HOMO and LUMO shapes, the electron ac-
ceptor is in the red region, and the green regions are the elec-
tron donor regions, from where the possible electron transfer
may be from where to the electron transfer during electronic
excitation. Seen in ΔE, the lowest value has S1 molecule and
the highest value has S2 and S3 molecules.
Compliance with ethical standards
Ethical statement/conflict of interest The authors declare that they have
no conflict of interest.
References
1. da Silva CM, da Silva DL, Modolo LV, Alves RB, de Resende MA,
Martins CVB et al (2011). J Adv Res 2(1):1–8
2. Schiff H (1866). Eur J Org Chem 140(1):92–137
3. Schiff H (1864). Ann Chem 131(1):118–119
4. Haas A, Lieb M, Schelvis M (1997). J Fluor Chem 83:133–143
5. Vaghasiya YK, Nair R, Soni M, Baluja S, Chanda S, Serb J (2004).
Chem Soc 69:991–998
6. Arafath MA, Adam F, Al-Suede FSR, Razali MR, Ahamed MBK,
Majid AMSA, Hassan MZ, Osman H, Abubakar S (2017, 1149). J
Mol Struc:216–228
7. Neelima KP, Siddiqui S, Arshad M, Kumar D (2016). Spectr Acta
Part A 155:146–154
8. Ganguly A, Chakraborty P, Banerjee K, Choudhuri SK (2014). Eur
J Pharma Sci 51:96–109
9. Shanty AA, Mohanan PV (2018). Spectrochim Acta Part A 192:
181–187
According to SAS images, the red and blue areas are areas
where solvent interaction is possible. These regions are where
oxygen and nitrogen atoms are present.

Struct Chem
10. Chithiraikumar S, Gandhimathi S, Neelakantan MA (2017). J of
Mol Struct 1137:569–580
44. Singh TS, Paul PC, Pramanik HAR (2014). Spectrochim Acta A
121:520–526
45. Tajbakhsh M, Chalmardi GB, Bekhradnia A, Hosseinzadeh R,
Hasani N, Amiri MA (2018). Spectrochim Acta A 189:22–31
46. Minkin VI, Tsukanov AV, Dubonosov AD, Bren VA (2011). J Mol
Struct 998:179–191
11. Zhang Y, Fang Y, Liang H, Wang H, Hu K, Liu X, Yi X, Peng Y
(2013). Bioorg Med Chem Lett 23:107–111
12. Joshi R, Pandey N, Yadav SK, Tilak R, Mishra H, Pokharia S
(2018). J Mol Struct 1164:386–403
47. Wang Q, Cai L, Gao F, Zhou Q, Zhan F, Wang Q (2010). J Mol
Struct 977:274–278
13. Guo Z, Xing R, Liu S, Zhong Z, Ji X, Wanga L, Lia P (2007).
Carbohydr Res 342:1329–1332
48. Zhao L, Hou Q, Sui D, Wang Y, Jiang S (2007). Spectrochim Acta
A 67:1120–1125
49. Liang Z, Liu Z, Gao Y (2007). Spectrochim Acta A 68:1231–1235
50. Gülseven Sıdır Y, Sıdır İ, Berber H, Türkoğlu G (2015). J Mol Liq
204:33–38
51. Payal R, Saroj MK, Sharma N, Rastog RC (2018). J Lumin 198:92–
102
52. Sıdır İ, Gülseven Sıdır Y, Berber H, Türkoğlu G (2016). J Mol Liq
215:691–703
53. Gülseven Sıdır Y, Pirbudak G, Berber H, Sıdır İ (2017). J Mol Liq
242:1096–1110
54. Gülseven Sıdır Y, Sıdır İ, Berber H, Türkoğlu G (2014). J Mol Liq
199:57–66
55. Sıdır İ, Gülseven Sıdır Y, Berber H, Demiray F (2015). J Mol Liq
206:56–67
56. Wang W, Li R, Song T, Zhang C, Zhao Y (2016). Spectrochim Acta
A 164:133–138
57. Yang Y-S, Ma S-S, Zhang Y-P, Ru J-X, Liu X-Y, Guo H-C (2018).
Spectrochim Acta A 199:202–208
58. Gowda A, Roy A, Kumar S (2017). J Mol Liq 225:840–847
59. Liu Z, Zhang J, Li T, Yu Z, Zhang S (2013). J Fluor Chem 147:36–
39
60. Rao GK, Kumar A, Singh MP, Kumar A, Biradar AM, Singh AK
(2014). J Organomet Chem 753:42–47
61. Lippert E (1955). Z Naturforsch 10a:541–545
62. Mataga N, Kaifu Y, Koizumi M (1945). Bull Chem Soc Jpn 29:
465–470
63. Bakhshiev NG (1964). Opt Spektrosk 16:821–832
64. Reichardt C (1994). Chem Rev 94:2319–2358
65. Kawski A (1966). Acta Phys Pol 29:507–518
66. Kawski A (1992) Progress in photochemistry and photophysics.
Boca Raton, Boston
67. Kawski A (2002). Z Naturforsch 57a:255–262
68. Kawski A (1964). Acta Phys Pol 25:285–290
69. Kawski A, Bojarski P, Kuklinski B (2008). Chem Phys Lett 463:
410–412
70. Kawski A (1992) in: J.F. Rabek (Ed.), Prog. Photochem.
Photophys., vol. 5, CRC Press, Boca Raton, p. 1. Ann. Arbor,
Boston
71. Chamma A, Viallet P (1970). C.R Acad Sci Paris Ser C 270:1901–
1904
14. Parsaee Z, Mohammadi K (2017). J Mol Struct 1137:512–523
15. Tehrani KHME, Hashemi M, Hassan M, Kobarfard F, Mohebbi S
(2016). Chin Chem Lett 27:221–225
16. Salehi M, Ghasemi F, Kubicki M, Asadi A, Behzad M, Ghasemi
MH, Gholizadeh A (2016). Inorg Chim Acta 453:238–246
17. Dileepana AGB, Prakasha TD, Kumar GA, Shameela RP,
Dhayabarana VV, Rajaram R (2018). J Photochem Photobiol B
183:191–200
18. Wang H, Yuan H, Li S, Li Z, Jiang M (2016). Bioorg Med Chem
Lett 26:809–813
19. Sabaaa MW, Elzanaty AM, Abdel-Gawadb OF, Arafa EG (2018).
Int J Biol Macromol 109:1280–1291
20. Ispir E, Toroğlu S, Kayraldız A (2008). Transit Met Chem 33:953–
960
21. Kumar BNP, Mohana KN, Mallesha L (2013). J Fluor Chem 156:
15–20
22. Cheng L-X, Tang J-J, Luo H, Jin X-L, Dai F, Yang J, Qian Y-P, Li
X-Z, Zhou B (2010). Bioorg Med Chem Lett 20:2417–2420
23. Sztanke K, Maziarka A, Osinka A, Sztanke M (2013). Bioorg Med
Chem 21:3648–3666
24. Hranjec M, Starcevic K, Pavelic SK, Lucin P, Pavelic K, Zamola
GK (2011). Eur J Med Chem 46:2274–2279
25. Jeevadason AW, Murugavel KK, Neelakantan MA (2014). Renew
Sust Energ Rev 36:220–227
26. Panda U, Roy S, Mallick D, Layek A, Ray PP, Sinha C (2017). J
Lumin 181:56–62
27. Zoubi WA, Mohanna NDA (2014). Spectrochim Acta A Mol
Biomol Spectrosc 132:854–870
28. Singh AK, Gupta VK, Gupta B (2007). Anal Chim Acta 585:171–
178
29. Gupta VK, Jain AK, Maheshwari G (2007). Talanta 72:49–53
30. Alizadeha K, Parooi R, Hashemi P, Rezaei B, Ganjali MR (2011). J
Hazard Mater 186:1794–1800
31. Singh AK, Mehtab S (2008). Talanta 74:806–814
32. Ganjali MR, Tamaddon A, Norouzi P, Adib M (2006). Sensors
Actuators B 120:194–199
33. Ganjali MR, Norouzi P, Daftari A, Faridbod F, Salavati-Niasari M
(2007). Sensors Actuators B 120:673–678
34. Ganjali MR, Norouzi P, Faridbod F, Ghorbani M, Adib M (2006).
Anal Chim Acta 569:35–41
35. Vijayalakshmi S, Kalyanaraman S (2013). Opt Mater 35:440–443
36. Shahid M, Salim M, Khalid M, Tahir MN, Khan MU, Brag AAC
(2018). J Mol Struct 1161:66–75
37. Bhuiyan MDH, Teshome A, Gainsford GJ, Ashraf M, Clays K,
Asselberghs I, Kay AJ (2010). Opt Mater 32:669–672
38. Jia J-H, Tao X-M, Li Y-J, Sheng W-J, Han L, Gao J-R, Zheng Y-F
(2011). Chem Phys Lett 514:114–118
39. Vijayalakshmi S, Kalyanaraman S, Krishnakumar V (2013).
Spectrochim Acta A 109:253–258
40. Wang K, Ma L, Liu G, Cao D, Guan R, Liu Z (2016). Dyes
Pigments 126:104–109
72. Kamlet MJ, Abboud JL, Abraham MH, Taft RW (1983). J Org
Chem 48:2877–2887
73. Kamlet MJ, Abboud JL, Taft RW (1997). J Am Chem Soc 99(18):
6027–6038
74. Catalán J (2009). J Phys Chem B 113(17):5951–5960
75. Catalán J (2012). J Phys Chem A 116:4726–4794
76. Catalán J (2009). J Phys Chem B 113:5961–5960
77. Reichardt C (1982). in H. Ratajczak, W.J. Orville-Thomas (Eds),
Molecular interactions, vol.3,John Wiley & Sons Ltd.
78. Reichardt C (2005). Solvents and solvent effects in organic chem-
istry. Third ed. Wiley-VCH, Weinheim Germany
79. Ravi M, Soujanya T, Samantha A, Radhakrishnan TP (1995). J
Chem Soc Faraday Trans 91:2739–2742
41. Chalmardi GB, Tajbakhsh M, Hasani N, Bekhradnia A (2018).
Tetrahedron 74:2251–2260
42. Sun C, Sun J, Che P, Chang Z, Li W, Qiu F (2017). J Lumin 188:
246–251
43. Jiaoa Y, Liua X, Zhoub L, He H, Zhoua P (2017). Duanb C Sensors
and Actuators B 247:950–956
80. Becke AD (1993). J Chem Phys 98:5648–5652
81. Frisch M J, Trucks G W, Schlegel H B, Scuseria G E, Robb M A,
Cheeseman J R, Scalmani G, Barone V, Mennucci B, Petersson G
A, Nakatsuji H, Caricato M, Li X, Hratchian H P, Izmaylov A F,

Struct Chem
Bloino J, Zheng G, Sonnenberg J L, Hada M, Ehara M, Toyota K,
Stratmann R E, Yazyev O, Austin A J, Cammi R, Pomelli C,
Ochterski J W, Martin R L, Morokuma K, Zakrzewski V G, Voth
G A, Salvador P, Dannenberg J J, Dapprich S, Daniels A D, Farkas
O, Foresman J B, Ortiz J V, Cioslowski J, and Fox D J, Gaussian 09,
Revision A.1 (Gaussian Inc., Wallingford, CT, 2009)
Fukuda R, Hasegawa J, Ishida M, Nakajima T, Honda Y, Kitao O,
Nakai H, Vreven T, Montgomery Jr JA, Peralta J E, Ogliaro F,
Bearpark M, Heyd J J, Brothers E, Kudin K N, Staroverov V N,
Kobayashi R, Normand J, Raghavachari K, Rendell A, Burant J C,
Iyengar S S, Tomasi J, Cossi M, Rega N, Millam J M, Klene M,
Knox J E, Cross J B, Bakken V, Adamo C, Jaramillo J, Gomperts R,
82. Dennington R, Keith T, Milam J, GaussView, Version 5, Semichem
Inc., Shawnee Mission KS, 2009