Photophysics of Dihydroquinazolinone Derivatives: Experimental and Theoretical Studies

Article abstract of DOI:10.1007/s10895-017-2051-0

Herein, we report the synthesis of two dihydroquinazolinone derivative 2-(2-Hydroxy-naphthalen-1-yl)-2, 3-dihydro-1H-quinazolin-4-one (1) and 2-(3-Methyl-thiophen-2-yl)-2,3-dihydro-1H-quinazolin-4-one (2) by using 2-aminobenzamide, 2-hydroxybenzaldehyde a

Full text of DOI:10.1007/s10895-017-2051-0

J Fluoresc
DOI 10.1007/s10895-017-2051-0
ORIGINAL ARTICLE
Photophysics of Dihydroquinazolinone Derivatives: Experimental
and Theoretical Studies
Mehboobali Pannipara1 & Abdullah G. Al-Sehemi1,2
Abul Kalam1,2 & T. N. Mohammed Musthafa3
&
Received: 5 October 2016 /Accepted: 19 February 2017
#
Springer Science+Business Media New York 2017
Abstract Herein, we report the synthesis of two dihydro-
quinazolinone derivative 2-(2-Hydroxy-naphthalen-1-yl)-2, 3-
dihydro-1H-quinazolin-4-one (1) and 2-(3-Methyl-thiophen-2-
yl)-2,3-dihydro-1H-quinazolin-4-one (2) by using 2-
aminobenzamide, 2-hydroxybenzaldehyde and 3-methyl thio-
phene-2-carboxaldehyde. The synthesized compounds were
characterized by 1H NMR, 13C NMR, FT-IR and its spectral,
photophysical, intramolecular charge transfer characteristics
were studied by absorption and emission spectroscopy. The syn-
thesized compound exhibits significant changes in their
photophysical properties depending on the solvent polarity. The
observed bathochromic emission band and difference in
Stokes shift on changing the polarity of the solvents
clearly demonstrate the highly polar character of the
excited state. The synthesized compounds were also
studied by density functional theory (DFT) and time-
dependent density functional theory (TDDFT) to expose
the reproducibility by computational means.
Introduction
Heterocyclic organic compounds containing atoms like
Sulphur, Nitrogen and Oxygen are the most abundant and
central skeletons that occur ubiquitously in a variety of syn-
thetic drugs and bioactive products [1]. Among them,
quinazoline and quinazolinone derivatives have attracted par-
amount attention owing to their widespread applications rang-
ing from biomedical science to material science [2–6].
Though quinazolinones and their derivatives are endowed
with diverse biological activities such as antitumour, antibiot-
ic, anti-defibrillatory, antipyretic, analgesic, diuretic, antihis-
tamine, antidepressant and vasodilating behavior [7–13], its
photophysical phenomena are only minimally studied and
are lesser known for their luminescent properties [14, 15].
Quinazolinone derivatives have attracted great interest for re-
searchers around the world due to its distinctive
photophysical properties such as intense luminescence,
large Stokes shifts and significant photostability which
can be tunable in response to the changes in pH and
polarity of solvents [16].
.
Keywords Dihydroquinazolinone derivatives Solvent
.
effect DFTstudies
The photophysical properties of pi-conjugated organic
fluorophores containing donor-acceptor groups originate
mainly from the intramolecular charge transfer state that de-
pends mainly on the substituent effect and solvent properties
[17]. Intramolecular charge transfer (ICT) in a molecule has a
significant influence on the luminescence properties and is
also required for nonlinear optical (NLO) processes. The
quinazolinone ring which act as a π-deficient aromatic hetero-
cycle having electron-withdrawing character, when incorpo-
rated with electron donating moiety can be used as push − pull
structures for intramolecular charge transfer (ICT).
Furthermore, upon incorporation of quinazolines in the back-
bone of pi- conjugated scaffolds, substantial reduction in the
HOMO − LUMO energy band gap is observed [18, 19]. Since
* Abdullah G. Al-Sehemi
agmasq@gmail.com
1
Research Center for Advanced Materials Science (RCAMS), King
Khalid University, P.O. Box 9004, Abha 61413, Saudi Arabia
2
Department of Chemistry, Faculty of Science, King Khalid
University, P.O. Box 9004, Abha 61413, Saudi Arabia
3
Department of Chemistry, MES Kalladi College, Mannarkkad,
Kerala 678583, India

J Fluoresc
the nitrogen atoms of the quinazolinone rings are easily avail-
able for protonation, hydrogen bond formation and chelation,
its derivatives have been exploited for the formation of supra-
molecular assemblies and sensors [20–23].
on a Bruker DPX-600 at 600 MHz and 150 MHz, respective-
ly, using TMS as the internal standard. The chemical shift
values are documented on δ scale and coupling constants (J)
in Hertz; Splitting patterns were entitled as follows: s: singlet;
d: doublet; m: multiplet. PG spectrophotometer was used to
record the UV-Vis electronic absorption spectra, and the
steady-state fluorescence spectra were measured using
Varain Cary Eclipse spectrofluorophotometer using a rectan-
gular quartz cell of dimensions 0.2 cm × 1 cm. The emission
was monitored at right angle.The fluorescence quantum yield
(ϕf) in different solvents were measured using a comparative
method where quinine sulfate [12] was used as the reference
and calculated using Eq. (1):
The absorption and emission properties of organic
fluorophores that carry a charge centre depend on the physical
properties of solvents such as polarity, polarizability and di-
electric constant and hence, offer an insight to their excited
state and thereby to access fundamental molecular properties
[24]. Excitation of a molecule by a photon may leads to redis-
tribution of electronic charges leading to conformational
changes in the excited-state and hence changes in dipole
moments. Knowledge of excited state electronic redistri-
bution in a molecule is quite useful for designing future
molecules that can be exploited in materials science
research [25]. Though there exist many methods avail-
able in the literature for determination of dipole mo-
ments, the one with solvent effect (solvatochromic
method); which is based on a linear correlation between
the wavenumbers of the absorption and emission maxi-
ma and solvent polarity function is the simplest and the
most widely accepted one as it is not equipment sensi-
tive and not limited to small molecules [26].
Iu As n2u
ϕu ¼ ϕs Â
Â
Â
ð1Þ
Is Au n2s
where ϕu, ϕs are the fluorescence quantum yields of the un-
known and standard, respectively,I denote the integrated emis-
sion intensity; A is the absorbance at excitation wavelength,
and n denote the refractive index of the solvent. The subscript
u and s stand for the unknown and standard, respectively.
In the current work, which is the continuation of our research
in the area of synthesis and photophysical properties of organic
molecules having donor–acceptor chromophores [27, 28], we
report here, the synthesis of two dihydroquinazolinone deriva-
tive by reported protocol and explored their spectral and
photophysical properties. The excited state properties of these
compounds were further examined by applying DFT based
calculation.
Synthetic Procedure
for 2-(2-Hydroxy-Naphthalen-1-Yl)-D-2,
3-Dihydro-1H-Quinazolin-4-One (1)
The title compound 1 was synthesized by a mixture of 2-
amino benzamide(10 mmol), 2-hydroxy benzaldehyde
(10 mmol) and sufanilic acid (1 mmol) in 50% aq ethanol
(25 mL) at 70 °C and the progress of reaction was monitored
by TLC. The obtained product was collected by simple filtra-
tion and washed several time with 50% aq. ethanol to get pure
product as yellow solid. Melting point 164 °C; IR (KBr):
Experimental
1
3150, 1669, 1492, 1417, 1360, 1153, 803, 707; H NMR
Materials and Methods
(600 MHz, CDCl3) δ = 6.64–6.90 (dt, 1H, J = 0.8 and
7.8 Hz, Ar-H), 6.90 (dt, 1H, J = 0.8 and 7.8 Hz, Ar-
H),6.68–6.70 (dd, 2H, J = 0.4 and 7.6 Hz, Ar-H), 7.05 (s,
1H, OH), 8.20 (s, 2H, NH), 5.35 (s, 1H), 7.22–7.26 (m, 1H,
Ar-H), 7.34 (d, 1H, Ar-H), 7.48–7.50 (m, 4H, Ar-H), 7.60 (dd,
1H, J = 1.6 and 8.0 Hz, Ar-H); 13C NMR (150 MHz, CDCl3)
δ = 82.4, 112.4, 114.9, 118.1, 126.8, 127.3, 125.6,
129.4136.3, 138.2, 136.3144.6, 147.8, 176.8.
All of the chemicals and solvents used in this study
were of analytical grade and used without further puri-
fication. The reactions were monitored by TLC with the
aid of UV light. 2-hydroxy-1-naphthaldehyde, 2-amino
benzamide and 3-Methylthiophene 2- carboxaldehyde
were purchased from Sigma–Aldrich and Merck. Stock
solution of the compounds and its dilutions were pre-
pared for UV–visible and fluorescent study at different
concentrations.
Synthetic Procedure for 2-(3-Methyl-Thiophen-2-Yl)
-2,3-Dihydro-1H-Quinazolin-4-One (2)
Spectral Measurements
Gallenkamp melting point apparatus was used to determine
the melting point and the infrared (IR) spectra were recorded
on Shimadzu FT-IR 8400S infrared spectrophotometer using
KBr pellets. The NMR (1H and 13C) spectra were recorded
The title compound 2 was synthesized by a mixture of 2-
amino benzamide (10 mmol), 3-Methylthiophene 2-
carboxaldehyde (10 mmol) and sufanilic acid (1 mmol) in
50% aq. ethanol (25 mL) at 700 C and the progress of reaction

J Fluoresc
Scheme 1 Synthetic route of
Compound 1 and 2
was monitored by TLC. The obtained product was collected
by simple filtration and washed several time with 50% aq
ethanol to get pure product as off-white solid. Melting point:
154-1560C; IR (KBr): 3027, 1640, 1542, 1417, 1360, 1153;
1H NMR (600 MHz, CDCl3) δ = 6.64–6.90 (dt, 1H, J = 0.8
and 7.8 Hz, Ar-H), 6.90 (dt, 1H, J = 0.8 and 7.8 Hz, Ar-
H),6.68–6.70 (dd, 2H, J = 0.4 and 7.6 Hz, Ar-H), 5.16 (s,
1H), 8.02 (s, 2H, NH), 7.36–7.42 (m, 1H, Ar-H), 7.34 (dd,
1H, Ar-H), 7.68–7.50 (d, 1H, Ar-H), 2.60 (s, 3H); 13C NMR
(150 MHz, CDCl3) δ = 32.6, 81.8, 116.4, 125.8, 126.3, 128.6,
129.4, 136.3, 138.2, 136.3144.6, 147.8, 178.6.
slight or negligible variation in the absorption spectra on chang-
ing the polarity of the solvents. Fig. 1 represents the
absorption spectra of both synthesized compounds re-
corded in some selective solvents and the corresponding
spectroscopic parameters in detail are collected in
Tables 1 and 2. Compound 1 displays two structureless
absorption band in the UV region (317–323 nm and
445–455 nm region) which are ascribed to S0 → S1or
S0 → Sn transitions with molar absorption coefficients
in the range of 16,100–24,200 M−1 cm−1 depending on
the solvent whereas compound 2 exhibit only one ab-
sorption band at ∼ 302–312 nm region with molar ab-
sorption coefficients in the range of 29,900–42,200 M−1.
The relatively high molar extinction coefficient in both
compounds indicates that these could be π-π* type of
transition as was found in other related compounds [29].
As inferred from Figs. 1 and 2, small blue shift is
observed in absorption spectra due to greater degree of
stabilization of the ground state in polar environments
[30, 31]. This kind of blue shifted spectra has often
reported in charge transfer systems due to the formation
of hydrogen bonded solvated cluster between probe
compounds and protic solvents.
Results and Discussion
Chemistry
Two quinazolinone derivatives having intramolecular charge
transfer characteristics, namely, 2-(2-Hydroxy-naphthalen-1-
yl)- 2, 3-dihydro-1H-quinazolin-4-one (1) and 2-(3-Methyl-
thiophen-2-yl)-2,3-dihydro-1H-quinazolin-4-one (2) have
been synthesized and characterized. The structures of com-
1
pounds were confirmed by IR, H NMR and 13C NMR.
The emission profile of both synthesized compounds
shows dramatic change on increasing the solvent polarity
from non polar to polar on exciting at 335 nm. As deciphered
from Fig. 2, the emission spectrum of compound 1 un-
dergo red shift of ∼23 nm on going from polar aprotic
solvents to polar protic solvents whereas the shift for
compound 2 is 44 nm; suggesting the involvement of
photo induced intramolecular charge transfer(ICT) state
formation following photoexcitation. The emission spectral
characteristics of compound 2 are predominated by emission
from locally excited (LE) state in nonpolar hydrophobic sol-
vents with one emission band. But increasing solvent polarity
Schemes 1 and 2 outlines the synthetic route to the synthesis
of two quinazolinone derivatives. Lippert–Mattaga and
Reichardt’s correlations were applied to calculate the
change in dipole moments of the synthesized com-
pounds. Solvents having different polarity have been
used to investigate the solvent effect on theabsorption
and emission spectra in detail.
Solvents Effect on Absorption and Emission Spectra
The electronic absorption spectra of compound 1and
2(∼10−5 M) have been recorded in different solvents show only
Scheme 2 Synthetic route of
Compound 1 and 2

J Fluoresc
results in a large red-shifted emission band in addition to the
short wavelength band suggesting the involvement of photo
induced intramolecular charge transfer (ICT) in the singlet
excited state with larger dipole moment in the excited state
[32]. Furthermore, apart from solvent polarity effect, hydro-
gen bonding effect of solvent also responsible for the red shift
of the emission band, as we can see in case of acetonitrile and
methanol where the solvent polarities are equal (expressed in
Δf). Compound 2 shows a red shift of 26 nm in methanol
(∼435 nm) from that of the emission band in acetonitrile
(∼409 nm) which clearly illustrate the hydrogen bonding ef-
fect in this charge transfer system [28].
Estimation of Dipole Moment Using Solvatochromic
Methods
Lippert- Mattaga and Reichardt’s methods has been applied to
calculate the difference in the dipole moment between the
excited and ground state, Eq. (S1, S2, S3, S4, S5 and S6)
(see Electronic supplementary information (ESI)) [33–36],
which is based on the correlation of solvent orientation polar-
izability parameter (Δf) and dimensionless microscopic sol-
vent polarity parameter (ENT ) of solvents with energy
difference between the ground and excited states
(Stokes’ shift). The calculated change in dipole mo-
ments (Δμ) for compounds 1 and 2 using Lippert-
Mattaga method, which is based on the slope of the
linear plot between Stokes shift with Δf, were found
to be 5.17 and 8.26 D (Fig. 3). Reichardt’s method;
which is based on the correlation of dimensionless mi-
croscopic solvent polarity parameter (ENT ) with Stokes’
shift, have reign over other method as it can include the
polarizability of solute molecules apart from dipole-
dipole interactions. The value for Δμobtained by this
method from the slope of the linear plot between ETN
Fig. 1 Electronic absorption spectra of (1 × 10−5 M) compound 1 (Panel
A) and 2 (Panel B)
Table 1 Spectral and photophysical parameters of compound 1 in different solvents
Δν (cm−1
)
ETN
Solvents
λabs (nm)
λem(nm)
ε M -1 cm−1
f
μ12 Debye
ET(30) K cal mol−1
Δf(D,n)
Acetonitrile
Chloroform
Dioxane
Ethyl Acetate
Toluene
THF
317
321
319
319
323
320
320
319
317
318
318
317
403
413
404
402
407
402
407
424
416
421
413
426
6732
6940
6595
6472
6390
6374
6680
7763
7507
7694
7233
8072
24,200
21,100
21,700
21,300
23,200
21,500
18,800
19,000
22,900
22,000
16,100
17,900
0.90
0.77
0.80
0.78
0.84
0.76
0.18
0.26
0.33
0.24
0.50
0.36
7.78
7.23
7.37
7.25
7.58
7.18
3.47
4.21
4.71
3.99
5.83
4.90
45.6
39.1
36
0.304
0.148
0.021
0.199
0.0132
0.2096
0.274
0.274
0.308
0.288
0.274
0.263
0.472
0.259
0.164
0.424
0.0987
0.21
38.1
33.9
37.4
43.8
49.2
55.4
51.9
49.2
63.1
DMF
0.404
0.570
0.762
0.654
0.79
Propanol
Methanol
Ethanol
EG
Water
1

J Fluoresc
Table 2 Spectral and photophysical parameters of compound 2 in different solvents
Δν (cm−1
)
ETN
Solvents
λabs (nm)
λem(nm)
ε M -1 cm−1
f
μ12 Debye
ET(30) K cal mol−1
Δf(D,n)
Acetonitrile
Chloroform
Dioxane
Ethyl Acetate
Toluene
THF
307
312
308
309
313
311
309
303
303
303
302
409
418
400
398
403
398
406
429
435
429
444
8123
8128
7468
7237
7135
7029
7732
9693
10,015
9693
10,590
41,600
38,000
34,800
38,400
37,000
36,400
42,200
32,600
34,200
34,700
29,900
1.26
1.02
0.83
1.04
1.01
0.77
1.24
0.91
0.85
0.95
0.94
9.05
8.22
7.37
8.24
8.18
7.10
9.02
7.65
7.39
7.83
7.76
45.6
39.1
36
0.304
0.148
0.021
0.199
0.0132
0.2096
0.274
0.274
0.308
0.288
0.263
0.472
0.259
0.164
0.424
0.0987
0.21
38.1
33.9
37.4
43.8
49.2
55.4
51.9
63.1
DMF
0.404
0.570
0.762
0.654
1
Propanol
Methanol
Ethanol
Water
with Stokes’ shift is found to be 2.01 and 3.11 D, respectively
(Fig. 4).
The oscillator strength ( f ) and transition dipole moment
(μ12) of the molecules gives an insight into the charge transfer
Fig. 2 Emission spectra of (1 × 10−5 M) compound 1 (Panel A) and 2
(Panel B)
Fig. 3 Correlations of Stokes shift with the solvent polarity function
((Δf) for 1 (Panel A) and 2 (Panel B)

J Fluoresc
where, f is the oscillator strength which shows the number of
electrons whose transition from ground to excited state gives
the absorption area of the electronic spectrum and Emax is the
energy maximum absorption in cm−1 and values for f and μ12
are listed in Tables 1 and 2.
Theoretical Studies
The ground and electronic excited states geometric optimizations
of both compounds are performed using density functional the-
ory (DFT) and time-dependent density functional theory
(TDDFT) methods, respectively, with the Gaussian 09 package
[39]. The DFT was treated according to Becke’s three parameter
gradient-corrected exchange potential and the Lee–Yang–
Parrgradient-corrected correlation potential (B3LYP) [40–42],
and all calculations were performed by using 6-31G⁄ basis set
[29]. This model has been widely used for geometry optimization
and the determination of electronic properties [43]. TDDFT has
been used to investigate absorption spectra and has proved to be
an efficient approach [44, 45]. The polarizable continuum model
(PCM) [46, 47] was used for evaluating bulk solvent effects at all
stages. The PCM-TDB3LYP/6-31G⁄ level of theory was used to
compute the absorption spectra in different solvents. The labeling
scheme is shown in Fig. 5.
We applied the DFT method to obtain the ground state geo-
metrical and electronic structure in the gas phase (as a control)
and in solvents. TD-DFTwas used to investigate the excited state
properties in the gas phase and solvents, together with the 6-
31G(d). In general, S1–C9, S1–C10, C7–N1 and C7–N2 bond
lengths increase from ground state to excited state for all solvents
used and the difference value 0.032, 0.032, 0.035, 0.035, 0.0043,
0.0046, 0.0046 and 0.0043A˘ respectively. On the other hand,
O2–H14, N1–H5 andN2–H7, bond lengths shortened from
ground to excited states, i.e., 0.015, 0.039, 0.015, 0.039, 0.026,
0.026, 0.014and 0.014Ao, respectively. In the both compounds,
the quinazolinone moiety are planar to other rings and have
dihedral angles of N12–C7–C9–C10 and S1–C9–C7–N2, be-
tween 120 to 170.0 in both ground and excited states.
Figure 6 illustrates the frontier molecular orbital, highest
occupied molecular orbitals (HOMO) and lowest unoccupied
molecular orbitals (LUMO). The HOMO is π bonding while
the LUMO is of antibonding character with π electrons dis-
tributed over the naphthalene and thiophene ring with charge
transfer. The HOMO–LUMO energy gap of this compound
was calculated at theB3LYP/6-31G⁄ level of theory, (Fig. 6).
Orbital energy level analysis at the B3LYP/6-31G⁄ level and
the resultant HOMO–LUMO energy gap (Egap) have been
used as an indicator of kinetic stability of a molecule. A large
HOMO–LUMO gap implies a high kinetic stability and low
chemical reactivity, because it is energetically unfavorable to
add electrons to a high-lying LUMO or to remove electrons
from a low-lying HOMO. As shown in Fig. 6, the HOMO is
delocalized over the quinazolinone moiety where as LUMOs
Fig. 4 Correlation of the Stokes’shift with ENT for compound 1 (Panel A)
and 2 (Panel B)
character of the fluorophore where the oscillator strength
values give a measure of the effective number of electronic
transition from the ground to excited state by providing the
absorption area in the electronic spectrum.
The experimental oscillator strength values were
ascertained using Eq. (2) [37]
ꢀ ꢁ
f ¼ 4:32 Â 10−9∫ ε ν dν
ð2Þ
where, ε is the numerical value for molar decadic extinction
coefficient measured in L mol−1 cm−1 and ν is the numerical
value of the wave number (cm−1).
Transition dipole moments (μ12) for absorption in various
solvents which gives the probability of radiative transitions,
was calculated using Eq. (3) [38]:
f
2
μ12
¼
ð3Þ
−7
4:72 Â 10
E
max

J Fluoresc
Fig. 5 Optimized molecular structure of compound 1 (Panel A) and 2 (Panel B)
are also distributed over the whole of the molecule. We also
computed the HOMO–LUMO orbitals energy gap at the same
level of theory in gas phase and found to be 4.36Ev for com-
pound 1 and 4.83 eV for compound 2 respectively. The
Experimental energy gap value of compound 1 in different
solvents ranging from 3.4–3.7 eV whereas for compound 2
ranging from 3.5–3.65 eV respectively. The results revealed
that the calculated energy gaps are not in bad agreement with
the experimental values.
1 and 2 (Fig. 7). During the scan, all the geometrical param-
eters were simultaneously relaxed while the dihedral angle
N2-C7-C9-C10 is varied in steps of 10°ranging from − 180°to
180° for compound 1 and S1-C9-C7-N2 for compound 2. The
relative energies of less stable conformers with respect to the
most stable form of compound 1 are 0.0 and 0.49 Kcal.mol−1
and 7.7 kcal mol−1 for the unstable rotamer. The energy dif-
ference between the most stable and other conformations of
compound 2 is 3.5 kcal mol−1.
For modeling and scanning calculation the initial guess of
compound 1 and 2, for the stable rotamers was first obtained
from the optimization using B3LYP/6-31G(p, d) and trans-
formed into the Z-matrix format with Babel program, the model
starting geometry of R1 was obtained by driving procedure in
Hyper Chem. To aid the future design of atropisomeric form of
Conformational Analysis
The conformational analysis was carried out through the po-
tential surface scan with B3LYP method using 6-31G** basis
set in order to ascertain the most stable geometry of compound
Fig. 6 The graphical presentation of the highest occupied and lowest unoccupied molecular orbitals of compound 1 and 2 at B3LYP/6-31G⁄ level of
theory

J Fluoresc
Fig. 7 The energy profile diagram of compounds 1 (Panel A) and 2 (Panel B)

J Fluoresc
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compounds 1 and 2, we set about to determining how well quan-
tum chemical methods calculation could predict the rotation bar-
riers around the C-C bonds on these compounds. To identify low
energy conformations, the potential energy surface shape has
been examined at the B3LYP/6-31G(p, d) levels. Potential ener-
gy surfaces of dihedral angle (N2-C7-C9-C10) for compound 1
and dihedral angle (S1-C9-C7-N2) for compound 2, from -180o
to +180o in 10o steps, shown in Fig. 7. There are two minimum
energy state found for the non-planar ground state of both com-
pounds 1 and 2 together with two transition states. All levels
of calculation of minimum structure and dihedral angle be-
tween quinazolinone rings and naphthalene ring for com-
pound 1 and thiophene ring for 2 was found to be very close
to ( 70o) (Fig. 7). All calculations were performed for isolated
molecules and solvents were not included. The maximum
energy species obtained by these methods is not transition
structures but the plot nonetheless provides a good approxi-
mation of the barrier to C-C bonds rotation. From the compu-
tational calculation, it appears that the OH group of naphtha-
lene moiety more difficult to passes on front of the
quinazolinone ring NH due to the hydrogen bond formed for
1 and due to clash of quinazolinone ring NH and methyl
substituent of thiophene ring of 2.
13. Mhaske SB, Argade NP (2006) The chemistry of recently isolated
naturally occurring quinazolinone alkaloids. Tetrahedron 62:9787–
9826
Conclusion
14. Cabrera-Rivera FA, Escalante J, Morales-Rojas H, Zigler DF,
Schmidt RD, Jarocha LE, Forbes MD (2014) Journal of
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fluorescent chemical sensor for Fe3+ based on blocking of intra-
molecular proton transfer of a quinazolinone derivative. Talanta 71:
171–177
16. Achelle S, Rodrıǵuez-Loṕez J, Robin-le Guen F (2014) Synthesis
and photophysical studies of a series of quinazoline chromophores.
J Organomet Chem 79:7564–7571
17. Asiri AM, Alamry KA, Pannipara M, Al-Sehemi AG, El-Daly SA
(2015) Spectroscopic investigation, photophysical parameters and
DFT calculations of 4,40 (1E,10E)-2,20-(pyrazine-2,5-diyl)
bis(ethene-2,1- diyl)bis(N,N-dimethylaniline) (PENDA) in differ-
ent solvents. Spectrochim Acta A Mol Biomol Spectrosc 149:
722–730
18. Su SJ, Caib C, Kido J (2012) Three-carbazole-armed host materials
with various cores for RGB phosphorescent organic light-emitting
diodes. J Mater Chem 22:3447–3456
In summary, two dihydroquinazolinone derivatives having intra-
molecular charge characteristics have been synthesized and char-
1
acterized by H NMR, 13C NMR and FT-IR. The spectral,
photophysical and intramolecular charge transfer characteristics
of these compounds were studied by absorption and emission
spectroscopy. It is found that polarity and hydrogen bonding
ability of the solvents play prominent effect on the absorption
and emission spectra. The dual emission in polar solvents, polar-
ity dependent red shifted emission band and large Stokes shift,
support the occurrence of ICT in the excited state of the studied
molecules. The density functional theory (DFT) was used to
compute ground and excited state geometries of the molecule.
The experimental results obtained are in good agreement with
theoretical values.
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4-arylvinyl-2,6-di(pyridin-2-yl) pyrimidines: effect on the optical
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