Synthesis, photochemical and luminescent properties of ortho-hydroxystyrylquinazolinone-linked benzocrown ethers

Article abstract of DOI:10.1016/j.jphotochem.2017.10.006

Photoinduced transformations of (E)-2-(2-hydroxystyryl)quinazolinone-linked benzo[15(18)]crown-5(6) ethers in solutions have been studied by using UV–vis absorption and NMR spectroscopy. These crown ethers were found to have dual emission at 520 and 650 nm, associated with proton-transfer tautomer emission (ESIPT-luminescence) as a rare case of excited-state proton-transfer reaction in the non-pseudocyclic chromophoric systems. It was established also, that the organic bases affect the luminescence intensity of solutions of these compounds in the 550–650-nm wavelength range. An X-ray crystallography analysis of molecular structures of crown ethers and their complexes in crystals has been carried out. The fact of reversible photo/thermal E-Z isomerization in DMF and Et₃N for these macroheterocyclic compounds has been confirmed. An opportunity to control the photochemical isomerization rate of quinazolinone 2-(hydroxyphenyl)ethenyl derivatives by changing pH of the medium has been demonstrated.

Full text of DOI:10.1016/j.jphotochem.2017.10.006

Journal of Photochemistry and Photobiology A: Chemistry 351 (2018) 16–28
Contents lists available at ScienceDirect
Journal of Photochemistry and Photobiology A:
Chemistry
journal homepage: www.elsevier.com/locate/jphotochem
Invited paper
Synthesis, photochemical and luminescent properties of ortho-
hydroxystyrylquinazolinone-linked benzocrown ethers
a
a
a,b
Irina G. Ovchinnikovaa, , Grigory A. Kim , Eugene G. Matochkina , Mikhail I. Kodess
,
*
Pavel A. Slepukhina, Igor S. Kovalevb, Emilia V. Nosovab, Gennady L. Rusinova,b
,
Valery N. Charushina,b
a
Postovsky Institute of Organic Synthesis, Ural Branch of the Russian Academy of Sciences, 22 ul. S. Kovalevskoi, 620990 Ekaterinburg, Russian Federation
Ural Federal University named after the First President of Russia B. N. Yeltsin, 19 ul. Mira, 620002 Ekaterinburg, Russian Federation
b
A R T I C L E I N F O
A B S T R A C T
Article history:
Photoinduced transformations of (E)-2-(2-hydroxystyryl)quinazolinone-linked benzo[15(18)]crown-5
(6) ethers in solutions have been studied by using UV–vis absorption and NMR spectroscopy. These crown
ethers were found to have dual emission at 520 and 650 nm, associated with proton-transfer tautomer
emission (ESIPT-luminescence) as a rare case of excited-state proton-transfer reaction in the non-
pseudocyclic chromophoric systems. It was established also, that the organic bases affect the
luminescence intensity of solutions of these compounds in the 550–650-nm wavelength range. An X-
ray crystallography analysis of molecular structures of crown ethers and their complexes in crystals has
been carried out. The fact of reversible photo/thermal E-Z isomerization in DMF and Et3N for these
macroheterocyclic compounds has been confirmed. An opportunity to control the photochemical
isomerization rate of quinazolinone 2-(hydroxyphenyl)ethenyl derivatives by changing pH of the
medium has been demonstrated.
Received 7 August 2017
Received in revised form 2 October 2017
Accepted 3 October 2017
Available online 4 October 2017
Keywords:
(E)-2-(2-hydroxystyryl)quinazolinone-
linked benzo[15(18)]crown-5(6) ethers
ESIPT-luminescence
Photoacids
Reversible photo/thermal isomerization
Photoswitching
© 2017 Elsevier B.V. All rights reserved.
1. Introduction
isomerization [9,10] are quite promising for development of pH-
sensitive photochromic materials. Recently, we have first estab-
Diaryl substituted ethenes and their heterocyclic analogues are
considered to be one of the basic groups of modern electrolumi-
nescent and photochromic materials, widely used in nonlinear
optics, lasers with tunable frequency, optoelectronic devices for
recording and storage of information, and molecular photo-
switches [1,2]. In the series of hetaryl substituted stilbenes, their
unsymmetrical derivatives [3,4] are of particular interest. Due to
lished the ability of ortho-hydroxystyrylquinazolinone 5a
(Scheme 1, 2) to undergo a reversible photo/thermal switch in
solutions [11]. The process of E-Z-isomerization is initiated by
irradiation with a light in the 300 ꢀ 400 nm range, while the
reverse Z-E-inversion is a dark process, which is accelerated
significantly at elevated temperatures. It has been shown that both
photochromic and luminescent properties of such compounds can
be regulated by changing pH of the medium.
the contribution of the n,p*-state, the presence of an acceptor
azine (azinone) core, in addition to electron-donating aryl
fragment in stilbene derivatives might be of considerable influence
on photochemical and photophysical behavior of these lumino-
phores [5]. Indeed, there are several publications concerning the
synthesis of (E)-2-styrylquinazolin-4(3H)-ones and studying of
their photophysical properties [4,6–10]. It should be noted that
compounds of this push-pull type, having a specific emission
As a rule, successful application of organic photoswitches
depends on light absorption in a visible area by their chromophoric
fragments, and it is besides determined by the presence of
noticeable fluorescence in an initial compound or a photoproduct
[2]. Hydroxystyrylquinazolinones are potential photoacids, name-
ly, compounds with increasing acidity in an electronically excited
state [12]. A dual emission connected with excited-state intra- or
intermolecular proton-transfer reaction is distinctive feature of the
certain photoacids [13]. One of approaches to improve photo-
physical and photochemical properties appears to be ionization of
pH-sensitive groups of photochromic frameworks. It is known, that
the crown ethers are able to activate such groups through the
ability and
a profound tendency to a photoinduced E-Z-
* Corresponding author.
E-mail address: iov@ios.uran.ru (I.G. Ovchinnikova).
https://doi.org/10.1016/j.jphotochem.2017.10.006
1010-6030/© 2017 Elsevier B.V. All rights reserved.

I.G. Ovchinnikova et al. / Journal of Photochemistry and Photobiology A: Chemistry 351 (2018) 16–28
17
standard program. Fluorescence spectra were recorded on a Varian
Cary Eclipse fluorescence spectrophotometer with mutually
perpendicular beams, the wavelength setting accuracy of 0.5 nm.
The measurements were carried out in the range of 190–800 nm in
SUPRASIL 111-QS 10 quartz cells at 298 K (Hellma, Germany), the
bandwidth around the stationary point of excitation/emission was
10 nm. The wavelength of the excitation stationary point was
assigned based on the maximum in absorption and emission
spectra each time, the wavelength of the emission stationary point,
based on the maximum in excitation spectra. The PEM bias was
700 V. The solvent luminescence was taken into account in the
spectra. The relative quantum yields of solutions were measured at
22 ꢁ1 ꢂC according to the procedure, given at www.jyhoriba.co.uk
(Jobin Yvon Ltd. 2 Dalston Gardens, Stanmore, Middlesex HA7 1BQ
UK). The control samples were fluorescein [19] (Fabs = 0.85) in
0.1 N aqueous solution of KOH and quinine bisulfate [19] (Fabs
=
0.55) in 0.1 N aqueous solution of H2SO4. 1H and 13C NMR spectra
were recorded on Bruker DRX-400 (400 and 100 MHz) and Bruker
AVANCE-500 (500 and 126 MHz) spectrometers in DMSO-d6 at
295 K, using TMS and DMSO-d6 (dC 39.5 ppm) as references. 1H and
13C signals in the NMR spectra were assigned using 2D experiments
1H–1H COSY, 1H–1H NOESY, 1H–13C HSQC, and HMBC. The mass
analyzer was a Bruker Daltonics MicrOTOF-Q II mass spectrometer
with an electrospray ionization source, a 6-port divert valve and
Scheme 1. Reversible photo/thermal E-Z-E isomerization of ortho-hydroxystyr-
ylquinazolinone 5a.
formation of inter- and intramolecular hydrogen bonds (H-bonds)
with their polyether macrocyclic cavity [14–17]. Besides that, the
self-assembling/hetero-assembling ability of crown ethers in
different media is the important factor in supramolecular
chemistry [3,18]. In this communication we wish to report
photophysical and photochemical behavior of (E)-2-(2-hydroxys-
tyryl)quinazolinone-linked benzo[15(18)]crown-5(6) ethers 6a-d
by comparison of their properties with those of the ethoxy
substitution derivate E-6e and acyclic analogues E-5a,b (Scheme 2).
2. Experimental
syringe pump kd Scientific with flow rate 180 mL/h. The instrument
controls were performed with HyStar 3.2 and microTOF control 2.3
patch 1 (Bruker Daltonics) software. The nominal resolution of the
instrument was 17,500. The instrument was operated in positive
ion mode with m/z range of 50–800. The capillary voltage was
4500 V, and the capillary exit was 166 V. The nebulizer gas pressure
was 0.4 bar, and the drying gas flow was 4 L/min. The drying
temperature was 250 ꢂC. The spectra average was set to 3, and the
summation was 5000, corresponding to 1 s sample time. The
transfer time was 70 microseconds, and the hexapole RF was 100
Vpp. A 6-point external instrument mass scale calibration was
performed before each sequence with lithium formate clusters by
infusing 10 mmol Lꢀ1 lithium hydroxide in isopropanol/0.2%
formic acid (1:1, vol/vol). Melting points were measured on a
Boetius heating microstage. Thin layer chromatography was
carried out on Silufol UV-254 plates. Spots were visualized under
the light of a low-pressure mercury lamp (6 W) or in iodine vapors.
Column chromatography was performed over silica gel (Merck,
230–400 mesh).
2.1. General methods and measurements
IR spectra were recorded on a Perkin Elmer Spectrum One IR
Fourier transform spectrometer using
a diffuse reflectance
sampling accessory (DRA). Electron absorption spectra were
recorded on a UV-2600 PC double-beam spectrophotometer
(Shimadzu, Japan) in the range of 190–700 nm with the
wavelength setting accuracy of ꢁ0.3 nm using a Shimadzu Scan
Scheme 2. Synthesis of substituted quinazolinones 2 – 6.

18
I.G. Ovchinnikova et al. / Journal of Photochemistry and Photobiology A: Chemistry 351 (2018) 16–28
2.1.1. X-Ray crystallography studies
2.1.3. Kinetic studies of (E)-2-(2-hydroxystyryl)quinazolinone-linked
benzo[15(18)]crown-5(6) ethers by absorption spectroscopy
1. Photochemical transformations of compounds E-6a-d
The X-ray diffraction analysis was carried out on a Xcalibur 3
automated diffractometer with a CCD detector (Mo-K
= 0.71073 Å, graphite monochromator, -scan technique, with a
1(step) at 150(2) for compound E-6b and E-8d, at 295(2) K for
a radiation,
l
v
(2
10ꢀ5 M) in DMF (dimethylformamide) and Et3N – DMF (1:1)
ꢃ
K
were carried out by recording UV spectra of irradiated solutions
with allowance for the initial absorption every 2 s until persistent
state of the solutions. 2. Thermal transformations of photo-steady
compound E-8b. Crystals of compounds E-6b, E-8b,d were
obtained by slow concentration of acetonitrile and chloroform
solutions. The set of reflections was obtained and processed using
the CrysAlis software [20]. The structures were solved by direct
method and refined by full-matrix least squares method first in
isotropic and then in anisotropic approximation on F2 for all non-
hydrogen atoms using the SHELXS–97 and SHELXL-97 programs
[21]. The hydrogen atoms were placed in geometrically calculated
positions and they were included in the refinement using a riding
model with dependent thermal parameters. Thermal ellipsoids are
given with 50% probability. The OCH2CH2-moiety of E-6b has
shown a thermal disordering into two positions with occupancy
coefficients 0.4/0.6 in crystals. The O(4) atom and nearest C-atoms
(Fig. 6) of the OCH2CH2-moiety of E-8b have shown a thermal
disordering into two position with occupancy coefficients 0.5/0.5.
The oxygen atoms of the NO3-anions of E-8b are also disordered
with occupancy coefficients 0.9/0.1 with particular overlapping of
solutions of compounds Z-6a-d (2
were carried out by recording UV spectra every 10 min. 3.
Spectrophotometric titration of solutions of E-6a-d (2
10ꢀ5 M)
ꢃ
10ꢀ5 M) thermostated at 75 ꢂC
ꢃ
with a strong base (Me4NOH or t-BuOK) were carried out until
permanent state, using a series of solutions with the ratio of
concentrations CE-5:Cbase from 1:1 to 1:25. The choice of solvent
(DMF) was caused by the poor solubility of crown ethers. However,
a weak solvatochromism of acyclic phenols E-5 [11] and ethoxy
analogue of crown ethers E-6e (S-Figure 13) in different organic
solvents allowed us to make all researches in DMF.
2.2. Materials and synthesis
The 4-aminobenzo-15-crown-5 and 4-aminobenzo-18-crown-
6 1a,b and 3,4-dimethoxyaniline (Scheme 2) were obtained by
synthetic protocols [23,24]. All another materials used for
synthesis were purchased from Aldrich and used without further
purification.
the thermal ellipsoids. E-6b (solvate): C32H34N2O8 2(C2H3N),
ꢃ
triclinic, space group
c = 15.2521(17) Å,
= 104.333(9)ꢂ,
V = 1680.0(3) Å3; Z = 2,
reflections measured (2.63 <
[Rint = 0.0382], R1 = 0.0468, wR2 = 0.1029 for 2422 reflections with
I>2 (I), R1 = 0.1419, wR2 = 0.1094 for all reflections. E-8b (solvate):
32H34KN3O11 C2H3N, monoclinic, space group P21/c, a = 9.9460(6)
Å, b = 15.6575(9) Å, c = 23.2478(16) Å,
= 90.00ꢂ, = 96.624(6)ꢂ,
= 90.00ꢂ, V = 3596.2(4) Å3; Z = 4, = 0.211 cmꢀ1 = 1.324 g cmꢀ3
18761 reflections measured (4.12 <
< 61.76ꢂ), 9754 unique
reflections [Rint = 0.0415], R1 = 0.0632, wR2 = 0.1522 for 4154 reflec-
tions with I>2 (I), R1 = 0.1535, wR2 = 0.2165 for all reflections. E-8d
(solvate): C32H33ClKN3O11 C2H3N, triclinic, space group -1,
a = 8.9885(4) Å, b = 13.9075(6) Å, c = 14.9053(6) Å,
= 99.901(3)ꢂ,
= 95.630(3)ꢂ, = 105.018(4)ꢂ, V = 1752.78(13) Å3; Z = 2,
= 0.294
cmꢀ1 = 1.423 g cmꢀ3; 14041 reflections measured (2.31 <
< 26.40ꢂ), 7166 unique reflections [Rint = 0.0386], R1 = 0.0557,
wR2 = 0.1542 for 5180 reflections with I>2 (I), R1 = 0.0819, wR2 =
C-1, a = 10.2056(10) Å, b = 11.6549(10) Å,
a
b
= 93.940(9)ꢂ,
g
= 105.066(8)ꢂ,
1
3
m
= 0.093 cmꢀ ,
r
= 1.298 g cmꢀ ; 10088
u
< 26.37ꢂ), 6581 unique reflections
2.2.1. Synthesis of (E)-2-(2-hydroxystyryl)quinazolinone-linked benzo
[15(18)]crown-5(6) ethers including their quinonoid form and acyclic
analogues
s
C
ꢃ
3-(3,4-dimethoxyphenyl)-2-methylquinazolin-4(3H)-one
(2b).
a
b
The 3,4-dimethoxyaniline 0.3 g, 1.7 mmol) and P2O5 (1 g) were
added to 2-methyl-3,1-benzoxazin-4-one (0.27 g, 1.7 mmol)
(obtained by reflux of anthranilic acid in freshly distilled acetic
anhydride [25]) in pyridine (15–20 mL). The reaction mixture was
kept on heating at 90–95 ꢂC for 18 h. When the reaction was
completed, the solvent was evaporated, and water (50 mL) was
added to the residue. The product was filtered off and purified by
using a chromatographic column (SiO2), eluent ethyl acetate–
hexane, 2:3. The 3-(3,4-dimethoxyphenyl)-2-methylquinazolin-4
(3H)-one (0.42 g, 73%, m. p. 232–233 ꢂE). Found: C 68.89, H 5.49, N
g
m
,
r
;
u
s
ꢃ
C
a
b
g
m
,
r
u
s
9.42%. C17H16N2O3 requires C 68.91, H 5.44, N 9.45. IR (DRA,
n
ns
,
,
,
0.1799 for all reflections. The atomic coordinates and other X-Ray
crystallographic experimental data for the structure of E-6b, E-8b,d
have been deposited with the Cambridge Crystallographic Data
Centre (CCDC1578408E-6b, CCDC1578409E-8b, CCDC1578410E-
8d). Copies of the data can be obtained free of charge on
application to The Director, CCDC, 12 Union Road, Cambridge
CB2 1EZ, UK [fax: internat +441223/336 033; e mail: deposit@ccdc.
cam.ac.uk].
cmꢀ1): 765 s, 779 m (arom.); 869 m, 921 m; 1021 s
(
Earomꢀꢀ
?
?
ꢀꢀ
E
alk); 1133 m
(
nas
,
ns
,
Ealk
–
?
); 1249 m
(
nas
Earomꢀꢀ
ꢀꢀ
E
alk); 1318 m, 1378 s, 1443 m, 1472 s, 1509 s; 1605 m
(d
,
E¼E
, C
¼
N); 1671 s (
d
,
E ?); 2841, 2933 m, 2966 m (d,
d
¼
EalkꢀꢀH); 3022 m, 3071 m (
/ppm: 8.10 (1
J = 7.4, J = 1.0 Hz, H-7), 7.65 (1
J = 7.6, J = 7.4 Hz, H-6), 7.08–7.13 (2H, m, H-13, H-10), 6.96 (1
J = 8.3, J = 2.4 Hz, H-14), 3.83 (3 , s,
12), 3.75 (3
11), 2.18 (3H, s, H-15). 13C NMR (DMSO-d6)
/ppm: 161.43
,
EaromꢀꢀH). 1H NMR (DMSO-d6)
d
=, d.d J = 7.6, J = 1.0 Hz, H-5), 7.83 (1=, d.d.d J = 8.0,
=, d J = 8.0 Hz, H-8), 7.50 (1
=
, d.d
, d.d
, s,
=
=
;
e
?
-
E
=
2.1.2. Studies of photophysical and photochemical properties of (E)-2-
(2-hydroxystyryl)quinazolinone-linked benzo[15(18)]crown-5(6)
ethers
;
e
?
-E
d
(C-4), 155.06 (C-2), 149.25 (C-11), 148.86 (C-12), 147.31 (C-8a),
134.46 (C-7), 130.44 (C-9), 126.57 (C-8), 126.28 (C-5, C-6), 120.51
(C-4a), 120.34 (C-14), 112.08 (C-10), 111.76 (C-13), 55.70
Solvents were distilled and dried according to the standard
procedures. Preparation of solutions and their spectrophotometric
studies were carried out in red light. Photochemical trans-
formations in solutions were carried out in 1-cm path length
hermetically closed quartz cells in a photochemical reactor, using a
DRSh-250 mercury discharge lamp (250 W) with air cooling
(23 ꢁ 2 ꢂC). Solutions were irradiated from the distance of 13 cm
with a light flux, passing through the system of focusing lenses and
SZS-7 or SZS-26 light filters (thermal filter) and UFS-6, in the short
wavelength range of 364–456 nm. The lumen output (150 mW)
was determined by using an IMO-2N meter of average power and
laser irradiation energy [22]. The light flux was directed into the
meter using quartz optical fibers.
(
;e? E ;e?ꢀꢀE
11), 55.63 ( 12), 23.88 (C-15).
ꢀꢀ
2-Methylquinazolinone-linked benzo[15(18)]crown-5(6) ethers
(3a,b). 4-Aminobenzo crown ether 1a or 1b (0.6 g, ꢄ2 mmol)
and P2O5 (1 g) were added to 2-methyl-3,1-benzoxazin-4-one
(0.5 g, 3 mmol) in pyridine (15—20 mL). The reaction mixture was
kept on heating at 90–95 ꢂC for 26 h. When the reaction was
completed, the solvent was evaporated, and water (50 mL) was
added to the residue. The product was filtered off and purified by
using a chromatographic column (SiO2), eluent ethyl acetate–
hexane, 3:2.
2-Methyl-3-(2,3,5,6,8,9,11,12-octahydrobenzo[b][1,4,7,10,13]pen-
taoxacyclopentadecin-15-yl)quinazolin-4(3H)-one (3a) (0.61 g, 68%,

I.G. Ovchinnikova et al. / Journal of Photochemistry and Photobiology A: Chemistry 351 (2018) 16–28
19
m. p. 176–177 ꢂE). Found: C 64.55, H 6.37, N 6.48%. C23H26N2O6
requires C 64.46, H 6.15, N 6.57. m/z (ESI) (%) 427.1867 (50) [(M
;
e
?
-
E
11). 13C NMR (DMSO-d6)
152.65 (C-2), 149.24 (C-11), 148.90 (C-12), 147.52 (C-8a), 135.31
(C ),134.59 (C-7),130.74 (C-18), 129.74 (C-9),129.04 (C-20),127.05
(C-8), 126.39 (C-5), 126.15 (C-6), 121.81 (C-15), 120.93 (C-14),
120.46 (C-4a), 120.08 (C ), 119.42 (C-19), 116.09 (C-17), 112.48 (C-
10), 111.76 (C-13), 55.78 (
11), 55.64 ( 12).
d/ppm: 161.53 (C-4),156.59 (C-16),
+H)+]. IR (DRA,
960 m; 1048 m (ns
1254 m (nas
Earomꢀꢀ
1511 s; 1606 m (
2911 m (
EalkꢀꢀH); 3065 m (
/ppm: 8.10 (1
J = 7.1, J = 1.3 Hz, H-7), 7.65 (1
J = 7.9, J = 7.1, J = 1.0 Hz, H-6), 7.09–7.07 (2H, m, H-10, H-13), 6.94
n
, cmꢀ1): 700 s, 776 s, 814 m (arom.); 875 m, 928 m,
b
,
Earomꢀꢀ
ꢀꢀ alk); 1328 m, 1382 s, 1448 s, 1470 s,
, C
?
ꢀꢀ
E
alk); 1131 m (nas
,
ns
,
Ealkꢀꢀ?);
,
?
E
a
d
,
E
¼
E
¼
N); 1668 s (
d
,
E¼
?
); 2865 and
;e
?
ꢀꢀ
E
;e?ꢀꢀE
d
,
d
,
EaromꢀꢀH). 1H NMR (DMSO-d6)
(E)-2-(2-hydroxystyryl)-3-(2,3,5,6,8,9,11,12-octahydrobenzo[b]
[1,4,7,10,13]pentaoxacyclopentadecin-15-yl)quinazolin-4(3H)-one
(6a) (0.14 g, 58%, m. p. 265–267 ꢂE). Found: C 67.60, H 5.58, N 5.27%.
d
=, d.d J = 7.9, J = 1.3 Hz, H-5), 7.83 (1=, d.d.d J = 8.1,
=, d J = 8.1 Hz, H-8), 7.50 (1=, d.d.d
C
32H34N2O8 requires C 67.91, H 5.70, N 5.28. m/z (ESI) (%) 531.2150
(100) [(M+H)+]. IR (DRA, , cmꢀ1): 695 s, 763 m (arom.); 849 s,
942 m, 982 m; 1053 m (ns ꢀꢀ alk); 1137 m (nas
Earomꢀꢀ
Ealkꢀꢀ ); 1249 m Earomꢀꢀ ꢀꢀ alk); 1304 m, 1338 m,
1457 m, 1512 and 1547 s; 1601 s and 1654 m ( , C N);
EalkꢀꢀH); 3071 m (
/ppm: 10.19 (1H, s,
),
, d J = 8.1 Hz, H-
, d.d.d J = 8.0, J = 7.1, J = 1.0 Hz, H-6), 7.22 (1 , d.d J = 7.8,
J = 1.5 Hz, H-20), 7.15 (1 , d.d.d J = 8.3, J = 7.1, J = 1.4 Hz, H-18), 7.11
(1H, d J = 8.4 Hz, H-13), 7.09 (1H, d, J = 2.4 Hz, H-10), 6.93 (1 , d.d
J = 8.4, J = 2.4 Hz, H-14), 6.84 (1 , d.d J = 8.3, J = 0.9 Hz, H-17), 6.78
(1 , t.d J = 7.5, J = 0.9 Hz, H-19), 6.72 (1H, d J = 15.6 Hz, H ), 4.14 (2
m, ?E=2), 4.07–3.99 (2 , m, ?E=2), 3.82 (2 , m, ?E=2), 3.75
(2 , t J = 4.4 Hz, ?E=2), 3.68–3.60 (8
, m, 4*?E=2). 13C NMR
(DMSO-d6) /ppm: 161.50 (C-4), 156.66 (C-16), 152.64 (C-2), 148.83
and 148.67 (C-11, C-12), 147.50 (C-8a), 135.51 and 134.58 (C , C-7),
(1
(2
(8
=
=
=
, d.d J = 8.3, J = 2.4 Hz, H-14), 4.16–4.00 (4
, d J = 4.3 Hz, ?E=2), 3.76 (2 , d J = 4.3 Hz, ?E=2), 3.67–3.60
, m, 4*?E=2), 2.18 (3H, s, H-15). 13C NMR (DMSO-d6)
/ppm:
=
, m, 2*?E=2), 3.81
n
=
,
?
E
, ns,
d
?
(nas
,
? E
161.40 (C-4),155.02 (C-2),148.92 and 148.65 (C-11, C-12),147.29 (C-
8a),134.47 (C-7),130.55 (C-9),126.57 (C-8),126.30 and 126.28 (C-5,
C-6), 120.61 (C-14), 120.50 (C-4a), 113.69 (C-10), 113.46 (C-13),
70.55 (?E=2), 70.53 (?E=2), 69.75 (?E=2), 69.73 (?E=2), 68.79
d
,
E¼E
¼
1678 s (
d
,
E¼?
); 2871 and 2922 m (
d
,
d,
EaromꢀꢀH); 3338 br s (OH). 1H NMR (DMSO-d6)
d
OH), 8.12 (1
7.85 (1
8), 7.50 (1
=, d.d J = 8.0, J = 1.4 Hz, H-5), 8.07 (1H, d J = 15.6 Hz, Hb
(
?E=2), 68.68 (?E=2), 68.55 (2*?E=2), 23.88 (C-15).
=, d.d.d J = 8.1, J = 7.0, J = 1.4 Hz, H-7), 7.76 (1=
2-Methyl-3-(2,3,5,6,8,9,11,12,14,15-decahydrobenzo[b]
=
=
[1,4,7,10,13,16]hexaoxacyclooctadecin-18-yl)-2-methylquinazolin-4
(3H)-one (3b) (0.55 g, 65%, m. p. 146–147 ꢂE). Found: C 63.81, H
6.52, N 5.91%. C25H30N2O7 requires C 63.82, H 6.43, N 5.95. m/z (ESI)
=
=
=
(%) 471.2121 (10) [(M+H)+]. IR (DRA,
n
, cmꢀ1): 699 s, 773 m, 798 m
Earomꢀꢀ ꢀꢀ alk); 1121 m
Earomꢀꢀ ꢀꢀ alk); 1317 s, 1354 s,
1380 s, 1425 m, 1469 s, 1515 s; 1591 m (
); 2899 m (
EalkꢀꢀH); 3011 m (
(DMSO-d6) /ppm: 8.10 (1
d.d J = 8.2, J = 7.1, J = 1.4 Hz, H-7), 7.65 (1
d.d.d J = 8.0, J = 7.1, J = 1.1 Hz, H-6), 7.10–7.08 (2H, m, H-10, H-13),
6.93 (1 , d.d J = 8.5, J = 2.4 Hz, H-14), 4.19–4.04 (4 , m, 2*?E=2),
3.83–3.70 (4 , m, 2*?E=2), 3.64–3.53 (12 , m, 6*?E=2), 2.18
(3H, s, H-15). 13C NMR (DMSO-d6)
/ppm: 161.38 (C-4), 155.05 (C-
=
a
=,
(arom.); 860 s, 944 m, 992 s; 1055 m (ns
); 1248 m (nas
,
?
E
=
=
(nas
,
ns
,
Ealk
–
?
,
?
E
=
=
d
,
E
¼
E
, C
¼
N); 1682 s (
d
,
d
E¼?
d
,
d
,
EaromꢀꢀH). 1H NMR
b
d
=, d.d J = 8.0, J = 1.4 Hz, H-5), 7.83 (1
=
, d.
130.71, 129.83 and 129.30 (C-9, C-18, C-20), 127.03 (C-8), 126.37 (C-
5), 126.13 (C-6), 121.75, 121.22, 120.42, 120.13 and 119.41 (C-4a, C-
14, C-15, C-19, Ca), 116.08 (C-17), 114.13 and 113.37 (C-10, C-13),
70.44 (?E=2), 70.40 (?E=2), 69.61 (2*?E=2), 68.71 (?E=2),
68.57 (?E=2), 68.55 (?E=2), 68.35 (?E=2).
(E)-2-(2-hydroxystyryl)-3-(2,3,5,6,8,9,11,12,14,15-decahydro-
benzo[b][1,4,7,10,13,16]hexaoxacyclooctadecin-18-yl)- quinazolin-4
(3H)-one (6b) (0.14 g, 57%, m. p. 230–232 ꢂE). Found: C 66.89, H
5.99, N 4.90%. C32H34N2O8 requires C 66.89, H 5.96, N 4.88. m/z (ESI)
=
, d J = 8.2 Hz, H-8), 7.51 (1=,
=
=
=
=
d
2), 148.52 and 148.24 (C-11, C-12), 147.29 (C-8a), 134.44 (C-7),
130.40 (C-9), 126.55 and 126.27 (2C) (C-8, C-5, C-6), 120.51 and
120.37 (C-14, C-4a), 113.09 and 112.80 (C-10, C-13), 69.90 (?E=2),
69.89 (?E=2), 69.81 (2*?E=2), 69.76 (?E=2), 69.74 (?E=2),
68.62 (?E=2), 68.53 (?E=2), 68.21 (2*?E=2), 23.86 (C-15).
(%) 575.2397 (100) [(M+H)+]. IR (DRA,
(arom.); 852 s, 967 m; 1051 m (ns
Earomꢀꢀ
Ealkꢀꢀ ); 1250 m (nas Earomꢀꢀ ꢀꢀ alk); 1302 s, 1339 m, 1457 m,
1511 s; 1601 s and 1656 m ( , C
EalkꢀꢀH); 3064 m (
(DMSO-d6)
H-5), 8.02 (1H, d J = 15.7 Hz, H
J = 1.3 Hz, H-7), 7.76 (1 , d J = 8.1 Hz, H-8), 7.50 (1
J = 7.0, J = 1.0 Hz, H-6), 7.25 (1 , d.d J = 7.7, J = 1.3 Hz, H-20), 7.16–7.11
(3 , m, H-10, H-13, H-18), 6.91 (1 , d.d J = 8.5, J = 2.3 Hz, H-14),
6.85–6.77 (3 , m, H , H-17, H-19), 4.17–4.01 (4 , m, 2*?E=2),
3.88–3.51 (16 /ppm: 161.46
, m, 8*?E=2). 13C NMR (DMSO-d6)
(C-4), 156.81 (C-16), 152.73 (C-2), 148.39 and 148.24 (C-11, C-12),
147.48 (C-8a), 135.86 and 134.49 (C , C-7), 130.55, 129.98 and
129.69 (C-9, C-18, C-20), 126.97 (C-8), 126.32 (C-5), 126.03 (C-6),
121.70, 120.94, 120.45, 120.39 and 119.29 (C , C-4a, C-14, C-15, C-
n
, cmꢀ1): 698 s, 771 m
,
?
ꢀꢀ alk); 1132 m (nas
E
, ns,
(E)-2-(2-hydroxystyryl)quinazolinone-linked
benzo[15(18)]
?
,
? E
E
crown-5(6) ethers (a general procedure). The corresponding
aldehyde 4a (or 4b and 4c) (1.7 mmol) and an equimolar amount
of H3BO3 (1.7 mmol) were added to a solution of compound 2b, 3a
(or 3b) (0.2 g,1.3 mmol) in acetic acid (30 mL). The reaction mixture
was kept on reflux for 24–26 h. After completing of the reaction,
the solvent was evaporated, and the product was purified by using
chromatography from different impurities, first of all, of the Z-
isomer, formed as a minor product (2–7%). Chromatographic
separation was carried out on a SiO2 column, eluent ethyl acetate–
hexane, the proportion of concentrations from 2:3 to 4:1,
respectively. The target product 5b, 6a, 6b (or 6e) was crystallized
from acetonitrile, while compounds 6c (or 6d) – from DMF.
(E)-3-(3,4-dimethoxyphenyl)-2-(2-hydroxystyryl)quinazolin-4
(3H)-one (5b) (0.16 g, 58%, m. p. 278–280 ꢂE). Found: C 71.96, H
5.07, N 6.98%. C24H20N2O4 requires C 71.99, H 5.03, N 7.00. IR (DRA,
d
,
E
¼
¼
N); 1682 s (
d,
E¼?); 2870 m
(d,
d
,
EaromꢀꢀH); 3315 br s (OH). 1H NMR
d
/ppm: 10.32 (1H, s, OH), 8.11 (1=, d.d J = 7.9, J = 1.3 Hz,
b
), 7.85 (1
=
, d.d.d J = 8.1, J = 7.0,
=
=, d.d.d J = 7.9,
=
=
=
=
=
a
=
d
b
a
19), 116.03 (C-17), 113.36 and 112.64 (C-10, C-13), 69.82 (?E=2),
69.77 (?E=2), 69.72 (2*?E=2), 69.65 (2*?E=2), 68.65 (?E=2),
68.47 (?E=2), 68.18 (?E=2), 68.06 (?E=2).
n
, cmꢀ1): 741 s, 768 m (arom.); 871 m, 914 s, 969 s; 1025 m (ns
,
,
Earomꢀꢀ
?
?
ꢀꢀ
E
alk); 1136 m
(
nas
,
ns
,
Ealk
–
?
); 1232 m
(
nas
(E)-2-(5-chloro-2-hydroxystyryl)-3-(2,3,5,6,8,9,11,12-octahy-
drobenzo[b][1,4,7,10,13]pentaoxacyclopentadecin-15-yl)quinazo-
lin-4(3H)-one (6c) (0.16 g, 61%, m. p. 275–278 ꢂE). Found: C 63.48,
H 5.12, N 5.08%. C30H29ClN2O7 requires C 63.77, H 5.15, N 4.96. m/z
Earomꢀꢀ
ꢀꢀ
E
alk); 1304 s, 1340 m, 1455 m, 1513 s; 1554 d, 1604,
1634 and 1653 s (
d,
E¼
E, C
¼
N,
E ?); 2840, 2936 and 2955 m (d,
¼
E
alkꢀꢀH); 3062 m (
d6)
8.07 (1H, d J = 15.6 Hz, H
7), 7.76 (1 , d J = 8.1 Hz, H-8), 7.50 (1
H-6), 7.20 (1 , d.d J = 7.8, J = 1.1 Hz, H-20), 7.17–7.11 (3
13, H-18), 6.94 (1 , d.d J = 8.4, J = 2.4 Hz, H-14), 6.85 (1
J = 0.8 Hz, H-17), 6.78 (1 , d.d.d J = 7.8, J = 7.4, J = 0.8 Hz, H-19), 6.68
(1H, d J = 15.6 Hz, H ), 3.85 (3 , s, , s,
12), 3.74 (3
d,
EaromꢀꢀH); 3303 br s (OH). 1H NMR (DMSO-
d
/ppm: 10.13 (1H, s, OH), 8.12 (1
=
, d.d J = 8.0, J = 1.3 Hz, H-5),
(ESI) (%) 565.1655 (100) [(M+H)+]. IR (DRA, , cmꢀ1): 697 s, 776 s,
n
b
), 7.85 (1
=
, d.d.d J = 8.1, J = 7.0, J = 1.3 Hz, H-
, d.d.d J = 8.0, J = 7.0, J = 1.0 Hz,
, m, H-10, H-
, d.d J = 8.3,
809 m (arom.); 846 s, 899 s, 940 m, 967 m; 1053 m
(
nas
ns
,
,
=
=
Earomꢀꢀ
?
?
ꢀꢀ
E
alk); 1119 m
(
nas
,
ns
,
Ealk
–
?
); 1248 m
(
=
=
=
Earomꢀꢀ
ꢀꢀ
E
alk); 1338 m, 1424 s, 1471 m, 1510 s, 1551 s; 1600 s,
=
1654 br s (
d,
E
¼
E, C¼N,
E
¼
?
); 2863 m and 2935 m (
d,
EalkꢀꢀH);
=
3083 m (
d
,
EaromꢀꢀH); 3331 br s (OH). 1H NMR (DMSO-d6)
d
/ppm:
a
=
;e
?
-
E
=
10.53 (1H, br.s, OH), 8.12 (1=, d.d J = 7.9, J = 1.4 Hz, H-5), 7.94 (1H, d

20
I.G. Ovchinnikova et al. / Journal of Photochemistry and Photobiology A: Chemistry 351 (2018) 16–28
J = 15.6 Hz, H
b
), 7.86 (1
=
, d.d.d J = 8.2, J = 7.2, J = 1.4 Hz, H-7), 7.76
, d.d.d J = 7.9, J = 7.2, J = 1.0 Hz, H-6),
, d J = 2.7 Hz, H-20), 7.18 (1 , d.d J = 8.7, J = 2.7 Hz, H-18),
, d J = 8.5 Hz, H-13), 7.09 (1 , d J = 2.4 Hz, H-10), 6.93 (1 , d.
d J = 8.5, J = 2.4 Hz, H-14), 6.85 (1 , d J = 8.7 Hz, H-17), 6.83 (1H, d
J = 15.6 Hz, H ), 4.14 (2 , m, ?E=2), 4.07–3.99 (2 , m, ?E=2),
3.82 (2 , m, ?E=2), 3.75 (2 , m, ?E=2), 3.68–3.59 (8 , m,
4*?E=2). 13C NMR (DMSO-d6)
/ppm: 161.40 (C-4), 155.53 (C-16),
152.36 (C-2), 148.83 and 148.73 (C-11, C-12), 147.35 (C-8a), 134.57
(C-7),134.22 (C ),129.91 (C-18),129.72 (C-9),128.82 (C-20),127.07
(C-8), 126.36 (C-5), 126.30 (C-6), 123.48 (C-15), 122.73 (C-19),
122.02 (C ), 121.25 (C-14), 120.49 (C-4a), 117.70 (C-17), 114.26 (C-
8.25 (1H, d J = 15.1 Hz, Hb), 8.02 (1H, d.d J = 7.9, J = 1.0 Hz, H-8), 7.75
(1
7.30 (1
7.11 (1
=
, d J = 8.2 Hz, H-8), 7.52 (1
=
=
=
(1H, d.d.d J = 8.3, J = 6.8 Hz, J = 1.5 Hz, H-6), 7.64 (1H, d J = 7.9 Hz, H-
5), 7.34 (1H, d.d.d J = 7.9 Hz, J = 7.1, J = 0.7, H-7), 7.09 (1H, d J = 8.4 Hz,
H-13), 6.99 (1H, d J = 2.2 Hz, H-10), 6.83 (1H, d.d J = 8.4, J = 2.2 Hz, H-
14), 6.77 (1H, d J = 7.5 Hz, H-20), 6.72 (1H, d.d.d J = 7.9, J = 7.2,
=
=
=
=
a
=
=
J = 1.0 Hz, H-18); 6.48 (1H, d J = 15.1 Hz, H
17); 5.88 (1H, t J = 7.2 Hz, H-19), 4.17 (2
?E=2), 3.81 (2 , m, ?E=2), 3.72 (2 , m, ?E=2), 3.64–3.59 (4
m, 2*?E=2), and 3.55 (8 , m, 4*?E=2).
The quinonoid form E-7d (a solution of E-6d in a 10-fold excess of
the base (Me4NOH /ppm:
5H2O)): 1H NMR (DMSO-d6, 500 MHz)
8.70 (1H, d J = 15.1 Hz, H ), 8.05 (1H, d.d J = 7.8, J = 1.0 Hz, H-8), 7.78
a
); 6.14 (1H, d J = 8.4 Hz, H-
=
=
d
=
=
, m, ?E=2), 4.06 (2 , m,
=
=
=
=,
=
b
ꢃ
d
a
b
10), 113.48 (C-13), 70.39 (?E=2), 70.37 (?E=2), 69.60 (2*?E=2),
68.70 (?E=2), 68.61 (?E=2), 68.55 (?E=2), 68.46 (?E=2).
(E)-2-(5-chloro-2-hydroxystyryl)-3-(2,3,5,6,8,9,11,12,14,15-deca-
hydrobenzo[b][1,4,7,10,13,16]hexaoxacyclooctadecin-18-yl)quinazo-
lin-4(3H)-one (6d). (0.15 g, 57%, m. p. 252–254 ꢂE). Found: C 62.92,
H 5.47, N 4.46%. C32H33ClN2O8 requires C 63.10, H 5.46, N 4.60. m/z
(1H, d.d.d J = 8.3, J = 6.8, J = 1.4 Hz, H-6), 7.67 (1H, d J = 8.0 Hz, H-5),
7.39 (1H, d.d.d J = 7.8, J = 7.1, J = 0.7 Hz, H-7), 7.09 (1H, d J = 8.4 Hz, H-
13), 7.01 (1H, d J = 2.2 Hz, H-10), 6.85 (1H, d.d J = 8.4, J = 2.2 Hz, H-
14), 6.82 (1H, d J = 2.5 Hz, H-20), 6.76 (1H, d.d J = 8.8, J = 2.5 Hz, H-
18), 6.69 (1H, d J = 15.1 Hz, H
a
), 6.24 (1H, d J = 8.8 Hz, H-17), 4.16
, m, ?E=2), 3.80 (2 , m, ?E=2), 3.73
, m, ?E=2), 3.63–3.59 (4 , m, 2*?E=2), 3.55 (8 , m,
(2
(2
=
, m, ?E=2), 4.06 (2
=
=
(ESI) (%) 609.1962 (98) [(M+H)+]. IR (DRA,
808 m (arom.); 847 s, 945 m; 1063 m (ns
Earomꢀꢀ
Ealkꢀꢀ ); 1246 m (nas Earomꢀꢀ ꢀꢀ alk); 1340 s, 1424 s,
1473 m, 1515 s, 1551 s; 1598 s, 1627 m, 1657 br s ( , C N,
); 2863 m and 2918 m ( EaromꢀꢀH);
EalkꢀꢀH); 3078 m (
3340 br s (OH). 1H NMR (DMSO-d6)
/ppm: 10.71 (1H, s, OH), 8.12
(1 , d.d J = 7.4, J = 1.2 Hz, H-5), 7.92–7.84 (2H, m, H , H-7), 7.76 (1
d J = 7.9 Hz, H-8), 7.51 (1 , t, J = 7.4 Hz, H-6), 7.35 (1 , d J = 2.4 Hz, H-
20), 7.17 (1 , d.d J = 8.7, J = 2.4 Hz, H-18), 7.12–7.10 (2H, m, H-10, H-
13), 6.97 (1H, d J = 15.5 Hz, H ), 6.91 (1 , d.d J = 8.5, J = 2.1 Hz, H-14),
6.84 (1 , d J = 8.7 Hz, H-17), 4.18–4.03 (4 , m, 2*?E=2), 3.85 (1
m, ?E=2), 3.76 (2 , m, ?E=), 3.69–3.50 (13 , m, ?E=
6*?E=2). 13C NMR (DMSO-d6)
/ppm: 161.47 (C-4), 155.86 (C-
16), 152.55 (C-2), 148.33 and 148.23 (C-11, C-12), 147.40 (C-8a),
134.86 (C-7), 134.60 (C ), 129.92, 129.82, 129.60 (C-9, C-18, C-20),
127.08 (C-8), 126.40 and 126.29 (C-5, C-6), 123.41, 122.63, 122.54,
120.96 and 120.51 (C , C-4a, C-14, C-15, C-19),117.67 (C-17),113.24
n
, cmꢀ1): 697 s, 772 s,
=
=
=
,
?
ꢀꢀ alk); 1129 m
E
4*?E=2).
(
nas
,
ns
,
?
,
? E
d,
E¼E
¼
2.2.2. Synthesis of (E)-2-(2-hydroxystyryl)quinazolinone-linked
benzo[15(18)]crown-5(6) ether complexes 8b,d with KNO3
E¼
?
d,
d,
d
The reaction mixture of the E-isomers 6b (or 6d) (ꢄ0.08 g) in
CHCl3 (15 mL) with KNO3 (0.5 g) was kept on reflux for 6 h, after
that KNO3 was filtered off. With chloroform being evaporated,
crystals of E-8b and E-8d complexes were obtained by slow
concentration of acetonitrile solution.
=
b
=
=,
=
=
a
=
=
=
=
,
KNO3-(E)-2-(2-hydroxystyryl)-3-(2,3,5,6,8,9,11,12,14,15-decahy-
drobenzo[b][1,4,7,10,13,16]hexa-oxacyclooctadecin-18-yl)-quinazo-
=
=
,
d
lin-4(3H)-one (E-8b). 1H NMR (DMSO-d6)
d
/ppm: 10.24 (1H, s, OH),
, d.d J = 7.9, J = 1.1 Hz, H-5), 8.06 (1H, d J = 15.5 Hz, H ), 7.85
, d.d.d J = 8.4, J = 7.1, J = 1.4 Hz, H-7), 7.76 (1 , d J = 7.9 Hz, H-8),
7.50 (1 , d.d.d J = 8.0, J = 7.1, J = 1.1 Hz, H-6), 7.22 (1 , d.d J = 7.7,
J = 1.3 Hz, H-20), 7.15 (2 , m, H-18, H-13, H-10), 6.96 (1 , d.d J = 8.5,
J = 2.3 Hz, H-14), 6.84 (1 , d J = 8.1 Hz, H-17), 6.77 (1 , t J = 7.8 Hz, H-
19), 6.73 (1H, d J = 15.5 Hz, H ), 4.21 (2 , m, ?E=2), 4.10 (2 , m,
?E=2), 3.84 (2 , m, ?E=2) and 3.74 (2 , m, ?E=2), 3.66 (2 , m,
?E=2), 3.59 (4 , m, 2*?E=2), 3.57 (6 , m, 3*?E=2).
8.11 (1
(1
=
b
b
=
=
=
=
=
a
=
=
and 112.52 (C-10, C-13), 69.80 (?E=2), 69.77 (?E=2), 69.74
(2*?E=2), 69.67 (?E=2), 68.65 (?E=2), 68.65 (?E=2), 68.47
=
a
=
=
=
(
?E=2), 68.13 (?E=2), 68.02 (?E=2).
=
=
=
(E)-2-(2-ethoxystyryl)-3-(2,3,5,6,8,9,11,12-octahydrobenzo[b]
=
[1,4,7,10,13]pentaoxacyclopentadecin-15-yl)quinazolin-4(3H)-one
KNO3-(E)-2-(5-chloro-2-hydroxystyryl)-3-(2,3,5,6,8,9,11,12,14,15-
decahydrobenzo[b][1,4,7,10,13,16]hexaoxacyclooctadecin-18-yl)qui-
(6e) (0.14 g, 58%, m. p. 101–103 ꢂE). Found: C 68.62, H 6.18, N 5.07%.
C32H34N2O7 requires C 68.80, H 6.13, N 5.01. IR (DRA,
n
, cmꢀ1):
nazolin-4(3H)-one (E-8d), 1H NMR (DMSO-d6)
d
/ppm: 10.58 (1H, s,
, d.d J = 7.9, J = 1.1 Hz, H-5), 7.94 (1H, d J = 15.5 Hz, H ),
, d.d.d J = 8.4, J = 6.7, J = 1.4 Hz, H-7), 7.76 (1 , d J = 8.1 Hz, H-
8), 7.51 (1 , d.d.d J = 7.8, J = 7.2, J = 0.7 Hz, H-6), 7.31 (1 , d J = 2.6 Hz,
H-20), 7.18 (1 , d.d J = 8.7, J = 2.6 Hz, H-18), 7.17 (2H, m, H-13, H-10),
6.97 (1 , d.d J = 8.4, J = 2.3 Hz, H-14), 6.85 (1 , d J = 8.7 Hz, H-17),
6.83 (1H, d J = 15.5 Hz, H ), 4.21 (2 , m, ?E=2), 4.11 (2 , m,
?E=2), 3.84 (2 , m, ?E=2), 3.75 (2 , m, ?E=2), 3.65 (2 , m,
?E=2), 3.60–3.57 (4 , m, 2*?E=2), 3.56 (6 , m, 3*?E=2).
698 s, 768 m (arom.); 868 s, 932 m, 982 m; 1049 m
(
nas
ns
,
,
OH), 8.12 (1
7.86 (1
=
b
Earomꢀꢀ
?
?
ꢀꢀ
E
alk); 1132 m
(
nas
,
ns
,
Ealkꢀꢀ
?
); 1244 m
(
=
=
Earomꢀꢀ
ꢀꢀ
E
alk); 1335 m, 1470 m, 1515 and 1546 s; 1597 and
=
=
1625 s (
d
,
E
=
E, C¼N); 1672 s (
d
,
E
¼
?); 2870 and 2929 m (
d
,
=
EalkꢀꢀH); 3077 m (
d
,
EaromꢀꢀH). 1H NMR (DMSO-d6)
d
/ppm: 8.12
), 7.86 (1
=
=
(1
=, d.d J = 7.9, J = 1.4 Hz, H-5), 8.02 (1H, d J = 15.6 Hz, H
b
=
,
a
=
=
=
=
d.d.d J = 8.1, J = 7.1, J = 1.4 Hz, H-7), 7.76 (1
(1 , d.d.d J = 7.9, J = 7.1, J = 1.0 Hz, H-6), 7.36 (1
H-20), 7.31 (1 , d.d.d J = 8.3, J = 7.3, J = 1.4 Hz, H-18), 7.12 (1H, d
J = 8.6 Hz, H-13), 7.09 (1H, d J = 2.3 Hz, H-10), 7.01 (1 , d J = 8.3 Hz,
H-17), 6.96–6.92 (2 , m, H-19, H-14), 6.82 (1H, d J = 15.6 Hz, H ),
4.18–4.10 (2 , m, ?E=2), 4.03 (2 , m, ?E=2), 4.00 (2H, q
J = 7.0 Hz, OCH2CH3), 3.82 (2
?E=2), 3.68–3.60 (8
OCH2CH3). 13C NMR (DMSO-d6)
16), 152.58 (C-2), 149.03(C-11), 148.86 (C-12), 147.41 (C-8a), 135.65
(C ), 134.60 (C-7), 130.98 (C-18), 130.88 (C-20) 129.83 (C-9), 127.10
(C-8), 126.39 (C-5), 126.25 (C-6), 123.20(C-15), 121.43 (C ), 121.14
=
, d J = 8.1 Hz, H-8), 7.51
=
=
=, d.d J = 7.7, J = 1.4 Hz,
=
=
=
=
2.2.3. Synthesis of (Z)-2-(2-hydroxystyryl)quinazolinone-linked
benzo[15(18)]crown-5(6) ethers and their complexes with KNO3
=
a
=
=
A solution of isomer E-6b (or E-6d) and E-8b (or E-8d) (ꢄ5 mg,
0.01 mmol) in DMSO-d6 (or in DMSO-d6 with Et3N (1:1),1 mL) was
placed into a 1-cm path length hermetically sealed quartz cell and
exposed to the light of a DRSh-250mercury discharge lamp
(250 W) using an UFS-6 light filter at the distance of 13 cm with air
cooling. The reaction progress was monitored by NMR. After 4 h of
exposure (for E-6b and E-6d) and 10 h (for E-8b and E-8d) (S-
Fig. 12), the 1H NMR spectra have shown that the solution
contained ꢄ 79% of photoinduced Z-isomer, respectively.
=
, t J = 4.4 Hz, ?E=2), 3.74 (2
=
, m,
=, m, 4*?E=2), 1.14 (3=, t J = 7.0 Hz,
d
/ppm: 161.51 (C-4), 157.44 (C-
b
a
(C-14), 120.66 (C-19), 120.46 (C-4a), 114.14 (C-10), 113.62 (C-13),
112.39 (C-17), 70.62 (?E=2), 70.56 (?E=2), 69.82 (?E=2), 69.81
(
?E=2), 68.81(?E=2), 68.64 (3*?E=2), 63.59 (OCH2CH3), 14.39
(Z)-2-(2-hydroxystyryl)-3-(2,3,5,6,8,9,11,12,14,15-decahydro-
(OCH2CH3).
The quinonoid form E-7b (a solution of E-6b in a 10-fold excess of
the base (Me4NOH /ppm:
5H2O)): 1H NMR (DMSO-d6, 500 MHz)
benzo[b][1,4,7,10,13,16]hexaoxacyclooctadecin-18-yl)- quinazolin-4
(3H)-one(Z-6b), 1H NMR (DMSO-d6)
d
/ppm: 9.78 (1H, s, OH),
ꢃ
d
8.14 (1
=
, d.d J = 7.9, J = 1.2 Hz, H-5), 7.79 (1 , d.d.d J = 7.9, J = 7.2,
=

I.G. Ovchinnikova et al. / Journal of Photochemistry and Photobiology A: Chemistry 351 (2018) 16–28
21
J = 1.5 Hz, H-7), 7.53 (1
7.24 (1 , d.d J = 7.8, J = 1.3 Hz, H-20), 7.07 (1
7.04 (1 , d J = 8.7 Hz, H-17), 6.96 (H, d J = 2.3 Hz, H-10), 6.88 (1
J = 8.6, J = 2.3 Hz, H-14), 6.76 (H, d J = 8.1 Hz, H-10), 6.67 (1H, d
J = 12.5 Hz, H ), 6.65 (1 , t J = 7.5 Hz, H-19), 6.01 (1H, d J = 12.5 Hz,
), 4.13 (2 , m, ?E=2), 3.98–3.94 (2 , m, ?E=2), 3.78 (2 , m,
?E=2), 3.68 (2 , m, ?E=2), 3.61 (2 , m, ?E=2), 3.56 (4 , m,
2*?E=2), 3.53 (6 , m, 3*?E=2).
=
, t J = 7.4 Hz, H-6), 7.49 (1
, t J = 8.7 Hz, H-18),
, d.d
=
, d J = 7.9 Hz, H-8),
styryl moiety and the “syn” orientation of the hydroxy group
relative to the nearest N(1) (E-6b) or N(2) heterocyclic atom (E-5a)
(Figs. 1 and 2) [11]. The conjugation system of styryl substituted
quinazolinones is nearly planar, the dihedral angle between the
mean square planes, passing through the (het)aryl fragments, is
equal to 14.44ꢂ. Due to a significant angle between the heterocyclic
plane (Figs. 1 and 2) and aromatic substituent at the position 3 of
quinazolinones (the type of E-5a) [11], the latter has a weak
=
=
=
=
b
=
=
Ha
=
=
=
=
=
=
(Z)-2-(5-chloro-2-hydroxystyryl)-3-(2,3,5,6,8,9,11,12,14,15-deca-
hydrobenzo[b][1,4,7,10,13,16]hexaoxacyclooctadecin-18-yl)quinazo-
influence on the p-electron system of this chromophore. Indeed,
the angle between the mean square planes, passing through the N
(1)C(25)N(2)C(17)C(23)C(22) atoms of (het)aryl fragment and the
C(15)C(16)C(12)C(13)C(14)C(11) atoms of phenoxy substituent in
E-6b crystals, is equal to 89.05ꢂ. Incorporating of the crown ether
fragment into the heterocyclic core of E-6 has not resulted in visible
shift of the long-wavelength absorption maximum in their US-Vis
spectra (Table 1). In spite of this fact, the ionophoric fragment
provides some advantages for new macroheterocyclic derivatives.
In contrast to E-5a (Fig. 1), another thymus type of the
intermolecular H-bond between the phenolic hydrogen atom
and oxygen atoms of the crown ether is realizing in crystals of E-6b.
The distances are equal to 2.16 and 2.18 Å, respectively (Fig. 2(b)).
Such hydrogen-bonding interaction of the phenoxy groups with
the ionophoric fragment of E-6 quinazolinones is able to activate
the hydroxy group in solutions. The ethoxy substitution derivate E-
6e and acyclic analogue E-5b of crown ethers were synthesized to
lin-4(3H)-one (Z-6d), 1H NMR (DMSO-d6)
d
/ppm: 10.04 (1H, s, OH),
, d.d J = 7.9, J = 1.2 Hz, H-5), 7.80 (1 , d.d.d J = 8.0, J = 7.0,
J = 1.5 Hz, H-7), 7.53 (1 , d.d.d J = 7.9, J = 7.0, J = 1.0 Hz, H-6), 7.50 (1
d J = 2.6 Hz, H-20), 7.47 (1 , d J = 7.9 Hz, H-8), 7.12 (1 , d.d J = 8.7,
J = 2.6 Hz, H-18), 7.06 (1 , d J = 8.4 Hz, H-13), 7.02 (1 , d J = 2.3 Hz,
H-10), 6.95 (1 , d.d J = 8.4, J = 2.3 Hz, H-14), 6.76 (1 , d J = 8.7 Hz, H-
17), 6.65 (1H, d J = 12.5 Hz, H ), 6.02 (1H, d J = 12.5 Hz, H ), 4.15
, m, ?E=2), 3.80 (2 , m, ?E=2), 3.71
, m, ?E=2), 3.56 (4 , m, 2*?E=2), 3.53
8.14 (1
=
=
=
=,
=
=
=
=
=
=
b
a
(2
(2
(6
=
=
=
, m, ?E=2), 4.04 (2
, m, ?E=2), 3.62 (2
, m, 3*?E=2).
=
=
=
=
KNO3-(Z)-2-(2-hydroxystyryl)-3-(2,3,5,6,8,9,11,12,14,15-decahy-
drobenzo[b][1,4,7,10,13,16]hexaoxacyclooctadecin-18-yl)- quinazo-
lin-4(3H)-one (Z-8b), 1H NMR (DMSO-d6)
/ppm: 9.73 (1H, s,
OH), 8.14 (1 , d.d J = 7.9, J = 1.2 Hz, H-5), 7.79 (1 , d.d.d J = 7.9, J = 7.2,
J = 1.5 Hz, H-7), 7.53 (1 , t J = 7.4 Hz, H-6), 7.48 (1 , d J = 8.1 Hz, H-8),
7.27 (1 , d J = 7.8 Hz, H-20), 7.06 (3 , m, H-18, H-17, H-10), 6.94
(1 , d.d J = 8.6, J = 2.3 Hz, H-14), 6.77 (H, d J = 8.0 Hz, H-10), 6.68 (1H,
d J = 12.5 Hz, H ), 6.64 (1 , t J = 7.5 Hz, H-19), 5.98 (1H, d J = 12.5 Hz,
), 4.19 (2 , m, ?E=2), 4.04–3.99 (2 , m, ?E=2), 3.82 (2 , m,
?E=2), 3.73 (2 , m, ?E=2), 3.64 (2 , m, ?E=2), 3.59 (4 , m,
2*?E=2), 3.56 (6 , m, 3*?E=2).
d
=
=
=
=
=
=
confirm this effect (cxe<a 2).
=
b
=
3.2. Studies of photophysical properties of crown ethers 6a–d
Ha
=
=
=
=
=
=
The photophysical properties of 5 and 6 phenols were studied
by UV–vis absorption and NMR spectroscopy in neutral, acidic
(CH3COOH) and basic (Et3N or Me4NOH and t-BuOK) solutions in
DMF. UV–vis spectra of 2 and 3 have had a short-wavelength
absorption maximum at 288 nm with a shoulder in the 300–
330 nm region. The remarkable luminescence of these solutions in
DMF has observed on a wavelength at 440 nm (Fig. 3) with 350-nm
shoulder. This emission can be explained by a charge-transfer
between electron donor (N(3)-atom) and acceptor (carbonyl
oxygen) in the heterocycle of excited molecules (like A*-state,
Scheme 3) [1,19]. Incorporation of stilbene moiety into E-5 and E-6
has led to an appearance of the long-wavelength maximum in
absorption spectra of their neutral solutions. The all absorption
curves of investigated stilbenes with maxima at 288 and 358–
360 nm have virtually identical profile (Figs. 4 and 5, Table 1). It is
noteworthy, the long-wavelength side of 360-nm absorption band
in hydroxy substituted E-5 and E-6 has a 7-nm bathochromic shift
with respect to ethoxy substituted E-6e. The low-intensive
emission with maximum at 445 nm of E-6e in normal Franck-
Condon excited state (Fig. 5(5), S-Fig. 13) is similar that of
compound 3b. In contrast to E-6e, the fluorescence spectra of E-5
=
KNO3-(Z)-2-(5-chloro-2-hydroxystyryl)-3-(2,3,5,6,8,9,11,12,14,15-
decahydrobenzo[b][1,4,7,10,13,16]hexaoxacyclooctadecin-18-yl)qui-
nazolin-4(3H)-one (Z-8d), 1H NMR (DMSO-d6)
d
/ppm: 10.04 (1H, s,
, d.d J = 7.9, J = 1.2 Hz, H-5), 7.81 (1 , d.d.d J = 8.4,
J = 6.9, J = 1.4 Hz, H-7), 7.54 (2 , m, H-6, H-20), 7.47 (1 , d J = 8.1 Hz,
H-8), 7.12 (2 , m, H-18, H-13), 7.10 (1 , d J = 2.3 Hz, H-10), 6.95
(1 , d.d J = 8.4, J = 2.3 Hz, H-14), 6.77 (1 , d J = 8.6 Hz, H-17), 6.64
(1H, d J = 12.6 Hz, H ), 6.01 (1H, d J = 12.6 Hz, H ), 4.20 (2 , m,
?E=2), 4.06–3.84 (2 , m, ?E=2), 3.76 (2 , m, ?E=2), 3.65 (2
, m, ?E=2), 3.58 (4 , m, 2*?E=2), 3.57 (6
OH), 8.14 (1
=
=
=
=
=
=
=
=
b
a
=
=
=
=
,
,
m, ?E=2), 3.61 (2
m, 3*?E=2).
=
=
=
3. Results and discussions
3.1. Synthesis and structures of the ortho-
hydroxystyrylquinazolinones
Functionalization of the styryl substituted quinazolinone 5a
[11] with crown ether fragments has been carried out according to
the earlier reported protocols [11,23,24] (Scheme 2, experimental
section). The C C bond formation techniques in the series of (het)
¼
arylstilbenes have often a specific nature, while condensation of 2-
methylazines [4] with aromatic aldehydes in the presence of zinc
chloride or sodium acetate does not provide high yields of the
target compounds. Furthermore, interactions between crown
ethers and catalysts of cationic nature, for example, complexes
with sodium or zinc ions are also known to inhibit the synthesis of
the target products. In particular, boric acid has been found to act
as a versatile catalyst for the synthesis of 6a-d (het)arylstilbenes,
bearing crown ether fragments, and the E-isomer proved to be the
predominant form. Besides that, due to positive effect of halogen
atoms on fluorescent properties of dye, [10] chloro derivatives of E-
6c and E-6d crown ethers have been obtained.
Fig. 1. Molecular packing of compound E-5a based on the X-ray diffraction studies,
formed by centrosymmetric dimers with intermolecularly close photosensitive C C
¼
According to the X-ray diffraction studies, both E-5a and E-6b
compounds in crystals have a similar trans-configuration of the
groups at the distance of 4.7 Å and stabilized by intermolecular hydrogen bonds (O
(2)ꢃ ꢃ ꢃH(1)O(1) 1.78 Å).

22
I.G. Ovchinnikova et al. / Journal of Photochemistry and Photobiology A: Chemistry 351 (2018) 16–28
Fig. 2. The molecular structure of compound E-6b based on the X-ray diffraction studies (a). Translation of E-6b molecules in bimolecular-layer formed by the thymus
intermolecular hydrogen bond (blue line) and stacking interactions of chromophore fragments of neighboring molecules with intermolecularly close C C groups at a
p
-
p
¼
distance of 3.93 Å (red line) in the crystals (b). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Table 1
Photophysical and photochemical characteristics of styryl(benzocrown)quinazolinones E-5,6.
Compound
Solvent
lexa/nm
lfla/nm
b/nm (
e
)
tE-Zc/s
tZ-Ed/m
lmax
Starting E-isomer
Reaction mixture
5a
5b
6a
6b
6c
6d
DMF
Et3N
DMF
Et3N
DMF
Et3N
DMF
Et3N
DMF
Et3N
DMF
Et3N
DMF
358
370
358
380
386
362
387
362
387
388
394
388
358
455
550
455
601
521
535
521
521
529
558
530
563
455
358 (20100)
350 (20760)
358 (20315)
358 (21815)
358 (14629)
359 (15370)
358 (14552)
359 (14275)
361 (19555)
369 (13387)
360 (19525)
368 (13680)
358 (23885)
358 (9950)
350 (8705)
358 (11680)
359 (11430)
358 (7481)
359 (6703)
358 (7482)
359 (5586)
358 (14880)
358 (8973)
360 (15980)
353 (6830)
345 (19265)
16
12
16
16
16
12
18
16
30
20
30
20
140
40
70
40
40
40
60
45
70
75
80
70
80
–
6e
a
The long wavelength maximum in excitation and emission spectra were measured at U 700 V and 500 V for DMF and Et3N (Et3N ꢀ DMF (1:1)), correspondently.
b
c
The absorption maxima and the corresponding extinction coefficients [19] (L molꢀ1 cmꢀ1) of styryl(benzo-crown)quinazolinones 5, 6 (2
Duration of photochemical E-Z isomerization of solutions upon exposure to irradiation.
ꢃ
10ꢀ5 mol Lꢀ1).
d
Duration of thermal Z-E isomerization of solutions thermostated at 75 ꢂC.
and E-6 have exhibited dual emission with certain differences
between acyclic and macrocyclic compounds. In luminescence
spectra of E-5, the low-intensive 455-nm emission band (lex = 288,
360 or 380 nm) has been the analogous those of 2, 3 and E-6e
compounds, while the long-wavelength maximum at 600 nm
manifested more clearly. The probable causes of a weak lumines-
cence were recently shown to be the conjugation breach between
phenolic and (het)arylvinylene fragments and the photochemical
1
isomerization of E-5 in solutions [11]. In 2D 1Hꢀꢀ H NOESY spectra
of E-5a/b in DMSO-d6 the turn of 2-hydroxyphenyl substituent
around the CꢀꢀC single bond relative to the ethenylquinazolinone
core was ꢄ90ꢂ according to the cross-peaks of almost equal
intensities between H(a), H(b) and each of the H-20 and HO-
proton of the styryl fragment (a selected correlations of protons are
shown in Scheme 3). Luminescence, which is scarcely distin-
guished in the visible wavelength range for E-5 solutions, is
increasing by an order of magnitude for crown ether derivatives
(Fig. 5, S-Fig. 14). Important feature of the emission spectra of E-6 is
the emergence of a new more intensive luminescence band at
ꢄ520 nm along with increasing band at 600 nm. In the 1H NMR
Fig. 3. The electron absorption (1, black line), fluorescence emission spectra (2, red
line, lex ꢄ 288 nm) of solution of compounds 2b (a) and 3b (b) (2
ꢃ
10ꢀ5 mol Lꢀ1, in
DMF). (For interpretation of the references to colour in this figure legend, the reader
is referred to the web version of this article.)

I.G. Ovchinnikova et al. / Journal of Photochemistry and Photobiology A: Chemistry 351 (2018) 16–28
23
Scheme 3. The excited-state proton-transfer tautomer processes in the non-pseudocyclic ortho-hydroxystyrylquinazolinone systems.
chains. The electronegative cavity of the crown ether is able not
only to stabilize the plane-conjugated chromophore fragment due
to intramolecular hydrogen bonds (according to NMR data), but
also to perform the function of the base (A – proton acceptor) upon
formation of the hydrogen-bounded donor-acceptor pair
–
[Dꢃ ꢃ ꢃHꢃ ꢃ ꢃA] with an acidic OH group (D – proton donor) [18].
Since the acidity of the OH group in the excited state increases
significantly, the proton completely passes into the crown ether
cavity with the formation of a separated ion pair [Dꢀ HA+].
Consequently, the 520-nm emission band can definitely be
associated with emission of the free phenolate-anion form due
to the proton-linking action of crown ether ring during the excited-
state proton-transfer (ESPT) reaction [13]. The efficiency of proton
transfer in plane-conjugated systems of photoacids can be
estimated with the values of the chemical shifts of OH protons
in the NMR spectra and the intensity of the 520 nm emission band
(Fig. 5). Efficiency increases with increase in the size of the
oligooxyethylene ring (from n = 1 to n = 2) and incorporation of the
electron-donating substituent (R " = Cl). Furthermore, this reaction
has been confirmed by 520-nm luminescence absence in the
acyclic E-5 derivatives and ethoxy substituted E-6e. The latter (E-
6e), which is generally treated as a non-ESIPT model due to the lack
of the hydroxyl proton, reveals a normal emission with maximum
at 445 nm. ESIPT-luminescence is characterized by large (ꢅ6000
cmꢀ1) [13] values of the Stokes’ shifts. The 520-nm peak frequency
for all E-6 crown ethers (Table 1) is Stokes shifted by more than
Fig. 4. Normalized electron absorption (black line), fluorescence emission spectra
(red line, lex ꢄ 358 nm) of solutions of compounds E-5a (1) and E-5b (2)
(2
10ꢀ5 mol Lꢀ1, in DMF). (For interpretation of the references to colour in this
ꢃ
figure legend, the reader is referred to the web version of this article.)
spectra of solutions E-6 in DMSO-d6 the phenolic proton is
exhibited as a singlet, which is shifted downfield to
d 10.18 (E-6a),
10.32 (E-6b), 10.53 (E-6c) and 10.70 (E-6d) as compared with
d
10.12 and 10.13 for E-5a,b compounds. Acidity of the hydroxy group
is increasing with growing of polyether cavity size and incorpo-
ration of electron-donating substituents (R” = Cl) in the E-6a, E-6b,
E-6c and E-6d series. According to 2D 1H–1H ROESY spectra, the
styryl moiety for example of E-6b/c molecules in solutions receives
a new conformation like that in the KNO3-complexes of E-8 (Fig. 9).
In this case, the hydroxyl group in molecule has oriented in the
direction of crown ether fragment, that is evidenced by high-
intensity cross peak between the hydroxyl proton and only
6500 cmꢀ1 with respect to the S0 ! S1
(pp*) absorption band at
358 nm.
The presence of ionogenic and non-ionogenic bases in solutions
of E-5 and E-6 has led to an increase in long-wavelength
luminescence of ortho-hydroxystyryl substituted quinazolinones.
However, their nature (Me4NOH and t-BuOK or Et3N) has had the
different influence on photophysical properties of crown ethers.
During photometric titration of E-5 and E-6 solutions with Et3N a
bathochromic shift of the absorption band does not occur (Table 1,
Fig. 6, S-Fig. 15). However, the profile of E-5 and E-6 fluorescence
curves (lex. ꢄ 380 nm, DMF – Et3N in the ratio of 1:1) has differed
from those for neutral solutions of E-5 and coincided with the
spatially close atom H(a), and cross peak between H(b) and H-
20 (Scheme 3). Using the X-ray data of E-8a it is possible roughly to
estimate the intramolecular distance between the hydroxyl proton
and oxygen atoms of the polyester moiety. This distance varies
within ꢄ3.7 ꢀ 4.7 Å. This distance in solutions can be shortened by
the conformational adjustment of the mobile oligooxyethylene

24
I.G. Ovchinnikova et al. / Journal of Photochemistry and Photobiology A: Chemistry 351 (2018) 16–28
Table 2
Selected photophysical characteristics of the quinonoid form of E-5a and E-6a-d
(2
ꢃ
10ꢀ5 mol Lꢀ1) in basic media (DMF and Me4NOH or t-BuOK).
a
Compound (2
ꢃ
10ꢀ5 mol L-1
)
C
E-3,5: Cbase
lex/nm lem/nm
(%)
Frel
5a
5b
6a
6b
6c
6d
1:20
1:20
1:10
1:8
1:10
1:7
520
517
520
525
490
490
607
610
607
606
605
604
12,5
17.3
13,6
12,5
19.5
15.4
a
The molar ratio of concentrations.
Fig. 5. Normalized electron absorption spectra (black line), fluorescence emission
spectra (red line,
l
ex ꢄ 388 nm) of solutions of compounds E-6 (2
ꢃ
10ꢀ5 mol Lꢀ1, in
DMF), E-6a (1), E-6b (2), E-6c (3), E-6d (4), E-6e (5). (For interpretation of the
references to colour in this figure legend, the reader is referred to the web version of
this article.)
Fig. 7. The electron absorption (1) and fluorescence emission spectra (2) of the
quinonoid form of E-6c (2
10ꢀ5 mol Lꢀ1) in DMF after the addition of Me4NOH in the
ꢃ
molar ratio of 1:10 (excitation and emission wavelength,
respectively).
l/nm: 490 and 605,
case with steady-state basic solutions of E-5 had unequivocally
confirmed the formation of the quinonoid form with the transfer of
a negative charge from the phenolate anion on the oxygen atom of
the keto-group [11] (Scheme 4). The same changes in chemical
shifts of all protons have been observed in the 1H NMR spectra of
solutions of E-6 in DMSO-d6 (experimental part) as well. A base
concentration required for a full shift of the equilibrium into the
quinonoid form of E-7 proved to be a half of that, used for E-5
(Table 2). This phenomenon appears to be associated with the
formation of Me4N+ or K+-complexes (like of E-8b,d (Figs. 9 and
10)) in solutions. In the 1H NMR spectrum, for instance, of
quinonoid form E-7d (S-Fig. 17 (2)), an observed simplification of
Fig. 6. The electron absorption (black line), fluorescence emission spectra (red line,
l
ex ꢄ 362 or 388 nm) of the E-6a (1), E-6b (2), E-6c (3), E-6d (4) (2
ꢃ
10–5 mol L–1, in
DMF – Et3N in the ratio of 1:1). (For interpretation of the references to colour in this
figure legend, the reader is referred to the web version of this article.)
emission spectra of E-6 (lex ꢄ 388 nm, DMF). In the emission
spectra of E-5 solutions, the disappearance of the short-wave
emission band at 440 nm and a significant increase in the intensity
of two long-wavelength emission bands at 540 nm and at 600 nm
is observed (S-Fig. 15). An increase in dual emission intensity for E-
6
solutions at 524 nm and at 600 nm is observed as well
proton multiplets of oligo oxyethylene fragment at
d 3.6–4.2 is
(
lex.ꢄ380 nm) (Fig. 6, Table 1). Relative quantum yields were
similarly that in E-8b complex discussed below (S-Fig. 18 (2)).
Consequently, a significant luminescence at 600 nm has been
result of the direct excitation of the quinonoid-anion form of crown
ethers (similarly E-5 [11]) and exhibited a normal Stokes’ shift (Dn
2546–3880) and high quantum yield (Table 2). The NMR and UV–
vis spectral data of E-5 and E-6 under normal and base media allow
unambiguously linking the emission bands at ꢄ530 nm and at
ꢄ605 nm with emission of the free phenolate-anion form and the
quinonoid-anion form, correspondently.
1.7% (E-5a,b and E-6a), 2.2% (E-6b), 2.9% (E-6c) and 3.1% (E-6d). The
addition of Et3N has led to the disappearance of the proton singlet
of OH group, but does not change shifts of all other protons of
ortho-hydroxystyrylquinazolinones in the 1H NMR spectra of E-5
and E-6 in DMSO-d6 (S-Fig. 21 (1,2)). Thus, NMR data of these
solutions have unequivocally indicated the intermolecular proton
transfer from the OH group of ortho-hydroxystyryl substituted E-5
or E-6a-d on Et3N molecule with formation of hydrogen-bonded
ion pair [13] – [Et3N
cence of E-5 and E-6 in Et3N has been result of the direct excitation
of their hydrogen-bonded form.
ꢃ
H+ꢃ ꢃ ꢃꢀO-(het)Aryl]. Consequently, fluores-
The spectrophotometric titration of crown ether E-6a-d
solutions with acetic acid (0.1 N) and alkali metal salts (a
potassium or sodium perchlorate concentration changed from
2 ) has led to the ESIPT-luminescence
0ꢀ5 to 10ꢀ2 mol Lꢀ1
ꢃ
According to the data of spectrophotometric titration of crown
ether solutions with Me4NOH and t-BuOK, a decrease of the light
absorption maximum lmax at 358 nm and an appearance of the
long-wavelength band at 490–520 nm have observed in their
electron absorption spectra (Table 2, Fig. 7). These significant
changes are related to the tautomeric transformation of conjugated
system E-6 into the quinonoid form E-7 (Scheme 4, Table 2, Fig. 7)
and the formation of charge transfer complexes. Earlier obtained
results of 2D homo- and heteronuclear NMR experiments in the
quenching, accompanied by a hypsochromic shift of the long-
wavelength maximum from 520 to 455 nm and the disappearance
of the maximumin lmax at 600 nm in their emission spectra
(Fig. 8(a,c)). An analogous disappearance of the 600-nm maximum
is also noted in acidic solutions of E-5 (Fig. 8(b), S-Fig. 16). The
spectral profile of the steady-state acidic and saline E-6a-d
solutions completely coincides with 455-nm band of E-6e in
neutral media (Fig. 5(5)). The well known cause of ESIPT-

I.G. Ovchinnikova et al. / Journal of Photochemistry and Photobiology A: Chemistry 351 (2018) 16–28
25
O
O
O
M
O
O
+
O
O
O
O
+
+
O
O
M
O
O
O
O
H
-
-
O
O
O
O
O
O
O
O
N
O
O
O
n
n
O
O
n
n
hν
N
N
hν
N
N
*
O
base
350 - 450 nm
~ 380 nm
Z-7 N
E-7 N
O
-
O
OH
E-6 N
hν
M+= K+, Me4N+
n
O
O
350 - 450
nm
O
O
O
O
O
+
O
H
O
O
O
+
O
-
H
O
O
O
O
O
n
O
O
O
O
n
N
*
-
*
N
O
hν
N
HO
N
O
N
N
Z-6
Z-6
Scheme 4. Photo/thermal E-Z-E isomerization of crown ethers 6a-d and their potassium complexes under neutral and basic conditions.
According to the mass spectra of the saline solutions, for example
E-6b and E-6c, the most probable composition of the formed
complexes can be estimated as 1:1 (S-Table 3). The X-ray data of E-
8b,d complexes with potassium nitrate (Figs. 9 and 10) allow to
throw some light on a supposed structure of NaClO4- or KClO4-
complexes in E-8b,d solutions. According to X-ray analysis, ligands
E-6 react with potassium ions into typical stoichiometric 1:1 E-8b,
d complexes of the guest-host type. In these structures of E-8b,d
the metal ion is completely encapsulated within macrocycle. Six
oxygen atoms of the polyether fragment are oriented at K+ ion with
the formation of nearly hexagonal cavity. The Oꢃ ꢃ ꢃK distances vary
from 2.71 to 2.82 Å. The cation in anion-covered E-8b,d complexes
is stabilized by two types of interaction. The first one is realized via
the hydrogen bond, passing through the nitrate anion to the HO-
group of the styryl fragment. In doing so the hydroxy group
acquires the ‘anti' orientation with respect to the heterocycle N(1)
atom. The distances in E-8b are equal to 1.97 Å (O(7)ꢃ ꢃ ꢃO(9)), 2.66 Å
(O(7)ꢃ ꢃ ꢃO(10)), 2.91 Å (O(9)ꢃ ꢃ ꢃK(1)) and 2.94 Å (O(11)ꢃ ꢃ ꢃK(1)). The
distances in E-8d are equal to 1.87 Å (O(7)ꢃ ꢃ ꢃO(11)), 2.55 Å (O(7)ꢃ ꢃ ꢃ
O(9)), 2.98 Å (O(10)ꢃ ꢃ ꢃK(1)) and 2.82 Å (O(9)ꢃ ꢃ ꢃK(1)). The second
type of interactions is realized via the intermolecular bond
Fig. 8. The changes in the electron absorption (1) and luminescence (emission
10ꢀ5 mol Lꢀ1
,
(
lex ꢄ 358 or 388 nm) (2)) spectra of the E-5b and E-6b,c solutions (2
ꢃ
DMF): (a) 2a ! 2b changes in E-6b solutions before and after addition of acetic acid
(0.1 N in DMF); (b) the 2a ! 2b changes in E-5b solutions before and after addition of
acetic acid (0.1 N in DMF); (c) the 2a ! 2b changes in E-6c solutions by
spectrophotometric titration with potassium perchlorate increased from 2
10ꢀ5
ꢃ
to 10ꢀ2 mol Lꢀ1
.
between potassium ion and oxygen atom of the C O group in
¼
luminescence quenching in such photoacids as aromatic alcohols is
rapid reprotonation of any excited alcoholate ion under acidic
conditions [12]. The cause of ESIPT-luminescence quenching in the
saline solutions can be the competitive formation of NaClO4- or
KClO4-complexes [15] with crown ethers, which blocks the binding
of the proton by this ionophore fragment (Scheme 3). Due to the
lack of crown ether fragment conjugation with chromophoric
system in E-6a-d, the electron absorption spectra of E-6a-d have
practically unchanged. This was also evidenced by the unchanged
proton signals of chromophoric quinazolinone core in the
comparable 1H NMR spectra of not saline and saline E-6 solutions
E-8b and E-8d in their H-centrosymmetric dimers. The distances K
(1)ꢃ ꢃ ꢃO(8) ([-x, ꢀy, 1-z] for E-8b and [1-x, 2-y, 1-z] for E-8d) is
2.80 Å (E-8b) and 2.75 Å (E-8d), respectively. The styrylquinazo-
linone system is nearly planar (Figs. 9 and 10), the dihedral angle
between the (het)aryl moieties is 12.70ꢂ (E-8b) and 23.97ꢂ (E-8d).
In the 1H NMR spectra of E-8b and E-8d solutions in DMSO-d6
enhancement of macrocycle symmetry derived from complex
formation is expressed in simplification of proton multiplets of
oligo oxyethylene fragment at
aromatic proton shifts of the benzo-crown ether moiety at
7.1, and CH CH moiety at 5.9–6.0 and 8.0–8.1 have also been
d
3.6–4.2 ppm (S-Fig.18). Changes of
d
6.9–
¼
d
a
b
in the field
d 7.45–8.15 (S-Fig. 18(1,2),19(1,2)). Therefore, it was not
observed (S-Fig. 18). Thus, the formation of anion-covered
complexes of the type E-8b and E-8d is the main cause of the
ESIPT-luminescence quenching in solutions [15]. To summarize
these results, the dual emission of the phenols in neutral media is
associated with the protolytic equilibrium of an excited undisso-
ciated phenol form (normal Franck-Condon excited state, 445-nm
emission band), the free phenolate-anion (520-nm emission band)
and quinonoid-anion (600-nm emission band) forms resulted by
proton-transfer tautomer excited state.
possible to trace the formation of complexes and their composition
by means of absorption spectroscopy. Complexation has been
studied by using mass (ESI) and NMR spectroscopy and XRD. The
addition of alkali metal salts has led to remarkable shifts of proton
resonance signals for instance in the 1H NMR spectra of E-6b
(DMSO-d6): for benzo-crown ether moiety they have been
observed in the field
d
3.56–4.18, 6.97 and 7.13–7.18, while for
6.66 and 8.11 (S-Fig. 18,19),
CH CH moiety – in the field
¼
d
a
b
indicating at the complexation process. Moreover, the all proton
signals of acyclic E-5 analogues remained unchanged in transition
to 1H NMR spectra of their saline solutions (S-Fig. 19a), being an
additional confirmation of the complexation of crown ethers.
The fluorescence properties of conjugated phenols such as the
styrylpyridines, styryldiazines [26] and 2-(20-hydroxyaryl)benza-
zoles [27] are known to connect with proton transfer in the excited
state and formation of the polar (like D* (Scheme 3)) and

26
I.G. Ovchinnikova et al. / Journal of Photochemistry and Photobiology A: Chemistry 351 (2018) 16–28
Fig. 9. The molecular structure of complexes KNO3-E-8b in centrosymmetric H-dimers based on the X-ray diffraction studies.
quinonoid form (like Q* (Scheme 3)) in excited molecules. Because
of increasing phenol acidity in the excited state, the proton transfer
is sufficiently rapid to occur during lifetime of this excited state.
The ESIPT process is accompanied by remarkable geometry
relaxation with production of the keto (quinonoid) form at the
singlet-excited state. Since polar (the free phenolate-anion form)
and quinonoid forms due to drastical difference in geometry have
different very long-wavelength emissions. The presence of these
forms can explain corresponding long-wavelength bands (500 ꢀ
700 nm), observed in a dual emission spectra of these hydroxy(het)
aryl systems [13,26,27]. The intramolecular proton transfer usually
occurs between donor and acceptor moieties hydrogen-bonded to
each other in the five- or six-membered pseudocycle [13].
However, a number of rare proton-transfer cases in the non-
pseudocyclic systems were also described [26,28,29].
Thus, a dual emission observed in neutral solutions of the acyclic
quinazolinones E-5 (emission bands at 455 and at 600 nm, Fig. 4)
and the benzo-crown ethers E-6 (emission bands at 455 (S-Fig. 17),
at 530 and at 600 nm, Fig. 5) is a lake rare case. However, the
comparison of electron absorption and emission spectral data of
investigated compounds leads to conclusion that the quinonoid-
form formation mechanisms in excited molecules of E-5 and E-6
under neutral conditions appear to have differences (Scheme 3). In
case of acyclic E-5, relaxation of the excited molecules A* seems to
be implemented by the PET-mechanism leading to tautomeric form
C*. The proton transfer at the final stage of the quinonoid form (Q*)
formation in aprotic polar DMF is supposed to connect with the few
plane-conjugated molecules self-associated into dimers similarly
those in E-5a crystals (Fig. 1) and to be in fact intermolecular
process. Incorporation of ionophoric crown ether fragment into
heterocyclic core of E-6 provides realization of a competitive
intramolecular proton transfer in excited plane-conjugated mole-
cules via intermediate B* (Scheme 3) into quinonoid form C* (Q*).
The crown ether cavity linking a proton in E-6 is able to stabilize the
free separated ion pair B* having ESIPT-luminescence at 520 nm.
The intramolecular formation of phenolate anion in neutral
solutions of E-6 can be to support by intermolecular proton transfer
in Et3N solutions of E-6 and E-5 with analogous luminescence at
ꢄ520–540 nm.
3.3. Studies of photochemical properties of crown ethers 6a-d
The proton-transfer photoinduced reactions are usually associ-
ated not only with tautomerism but also with the geometric
isomerism(E-Zisomerization)ofphotochromicconjugatedsystems
[13,27]. Recently, we have established the ability of ortho-
Fig. 10. The molecular structure of complexes KNO3-E-8d in centrosymmetric H-dimers based on the X-ray diffraction studies.

I.G. Ovchinnikova et al. / Journal of Photochemistry and Photobiology A: Chemistry 351 (2018) 16–28
27
hydroxystyrylquinazolinone 5a (Scheme 1) to undergo a reversible
photo/thermal switch in solutions [11]. The processes of a light-
inducedE-Zisomerizationofcrownethers6a-dandtheirpotassium
complexes (Scheme 4) under neutral and basic conditions have
been studied by using 1H NMR and UV–vis absorption spectroscopy
(experimental part) as well.
apparently associated with some additional contribution of ESIPT-
luminescence of the few plane-conjugated molecules in Z-form
(Scheme 4). It is also worth noting that the simultaneous ESPT-
reaction induced by light in the same wavelength range in neutral
media or triethylamine assists a significant acceleration of E-Z-
isomerizationofE-5andE-6(Table1)incomparisonwithlowrateof
E-6e (Table 1) and styrylquinazolinones without hydroxyl group
[11]. The realization of the two mechanisms of photoisomerization
can explain such acceleration. There are the usual rotational
mechanism for stilbenes [13] and deactivation of the excited
quinonoid-anion form E-6 [27], which may be accompanied by low
It has been found, that E-isomers of 6a-d demonstrate the
identical reversible photo/thermal E-Z-E isomerization (Scheme 4)
withE-5a[11] inneutralmedia(Table1, S-Fig.18(1,3),20). IntheUV–
vis spectra of these solutions, the E-Z-transformation induced by
UV-light at 350–450 nm has been accompanied by the intensity
diminution of the absorption band up to a photostationary state
(PSS). The PSS in the irradiated solutions of E-6 has been attained
within ꢄ12–20 s, which is confirmed by isobestic points (Fig.11) on
thetitrationcurvesintheirUVspectra.IntheemissionspectratheE-
Z-transformation has been accompanied by two-fold diminution of
ESIPT-luminescence of crown ether E-6 solutions. In the 1H NMR
spectra of irradiated solutions of 6b in DMSO-d6 the ratio of E- to Z-
isomer in the point of photo-transformation equilibrium reached
21:79 from the integral ratio of the observed peaks (S-Fig. 18(1 and
3)). The formation of Z-isomers of 6a-d is confirmed by the
barrierrotationaroundordinary
EꢀꢀEbondtothequinonoid-anion
form Z-6 with further nonradiative recombination up to phenol Z-6
(Scheme 4). The photoinduced E-Z-isomerization under strong
basic conditions can confirm the latter mechanism.
Under strong basic conditions, the photoinduced E-Z-isomeriza-
tion slows down by three orders (up to 20 min and more) due to the
stability of quinonoid complexes E-7 and the growing intensity of
the luminescence of these crown ether solutions. According to the
UV–vis spectra of compounds E-7c (Scheme 4), redistribution of the
absorbance maxima has connected with the hypsochromic shift of
the long-wavelength band from 490 nm to 422 nm, and disappear-
ance of the short-wavelengthband at330 nm (Fig.12). The presence
of the isobestic points in absorption spectra of irradiated solutions
of crown ethers E-7 may indicate the formation of PSS with a
predominant content of one from Z-forms 7. Since the PSS spectral
profile of crown ethers in strongly basic media differs significantly
from that under neutral conditions (including Et3N), the ethers can
apparentlyexist in the only quinonoid form of Z-isomer (Scheme 4).
Photolysis for example of crown ether E-8b and E-8d complexes
with KNO3 in solutions of DMF and DMSO-d6 has been studied also.
Inparticular,intheUV–visspectraofthecomplexE-8bsolutionsthe
light-induced E-Z-transformation accompanied by a diminution of
intensity of the absorption long-wavelength band up to PSS is
observed in the region of 350–450 nm. In this case, the rate of E-Z
photoisomerization of E-8b is 2.5–3 times slower (to 150 s), than
that for E-6b. In the 1H NMR spectra of E-8b solutions in DMSO-d6
the PSS resulting from the photolysis is confirmed by the set of
proton signals of the E- and Z-isomer in the ratio of 20:80, according
to their integrated intensities (S-Fig. 18(2,4)). The differences in 1H
chemical shifts between Z-6b and Z-8b isomers demonstrate
unequivocally the stability of the complexes during their trans-
formations into the Z-form. In particular, the proton resonances of
appearance of doublets of vicinal protons of the C C bond in the d
¼
5.9–6.7 ppm region with the spin-spin coupling constant of 12.5 Hz
(experimental part). In contrast, the reverse thermal Z-E-isomeri-
zation (according to 1H NMR and UV spectra) occurred slowly in the
dark (ꢄ30 h) at room temperature, being accelerated considerably
(45–70 min) at 75 ꢂC (S-Fig. 20). The rates of the photoinduced E-Z
and thermal Z-E-isomerization of the crown ethers E-6a,b are
comparable with that of E-5 (Table 1), while these rates for E-6c,d
slow down due to the electron-donating substituent (R” = Cl)
increasing luminescence intensity.
Compounds E-5 and E-6 in triethylamine have had appreciable
luminescence, as mentioned above. It has previously been shown,
that with the increaseof luminescence, the rate of photochemical E-
Z-transformation of (E)-2-styrylquinazolin-4(3H)-ones in solutions
decreases, and in some cases this process is accompanied by the
complete destruction of chromophores [11]. Nevertheless, the
spectral studies of E-5 and E-6 in triethylamine have shown that the
E-Z-E photo/thermal isomerization of styrylquinazolinones is
similar to that, proceeding under neutral conditions (Table 1, S-
Fig. 21 and 22). In the 1H NMR spectra of irradiated solutions of 6b in
DMSO-d6 with Et3N (ꢄ10ꢀ1 mol Lꢀ1) the same 20/80 ratio of E- and
Z-isomer in PSS has been observed (S-Fig. 21a (3)). Atthe same time,
ESIPT-luminescence of crown ethers reduces by only half in their
irradiated solutions without change of the spectral profile of the
emission curves (Fig. 11, S-Fig. 23, S-Table 4). This feature is
benzo-crown ether E-8b are observed at
d 6.9–7.1, 3.6–4.2, while
CH CH protons are exhibited in 5.9–6.0 and 8.0–8.1 (S-Fig.18).
¼
d
a
b
Fig.11. The changes in the electron absorption spectra of a solution of compound E-
6c (2
10ꢀ5 mol Lꢀ1, DMF) in the process of E-Z photoisomerization (1a (the spectrum
ꢃ
Fig. 12. The changes in the electron absorption spectra of E-7c (2
DMF in the presence of t-BuOK (C5:Ct-BuOK 1:10) during E-Z photoisomerization.
ꢃ
10ꢀ5 mol Lꢀ1) in
of the starting E-isomer) ! 1b (the spectrum of the photo-steady mixture with the
Z-isomer). The changes in fluorescence emission spectra E-6c at wavelength ꢄ 520
nm (2a ! 2b, lex 388 nm).

28
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Incorporation of ionophoric crown ether fragments into the
position 3 of heterocyclic core has significantly improved photo-
physical characteristics of quinazolinones E-6a-d with retention of
their photochromicproperties, similar tocompound E-5. The crown
ethers E-6 have had the dual luminescence bands at 520 nm and at
600 nm, associated with ESIPT-mechanism. Use of X-ray diffraction
and NMR techniques has revealed the role of ionophoric polyether
moiety in the binding of proton, and in ionization of the hydroxy
group with the increase in acidity of E-6. In UV–vis spectra of basic
solutions of E-6, a bathofluoric shift, similar to E-5, of the long-
wavelength high-intensive band at 600 nm has connected with
emission of the tautomeric quinonoid form E-7, while 520-nm band
has attributed to emission of the phenolate anion form. The causes
of ESIPT-luminescence quenching under acidic conditions and in
saline solutions have been found. The crown ethers E-6 have
demonstrated commensurate rates with reversible photo/thermal
switching of E-5 in neutral DMF and Et3N solutions. In doing so, the
process of E-Z-isomerization is initiated by UV–vis light in the 300–
400 nm wavelength range, inverse Z-E isomerization is a dark
process, which is accelerated with increasing a temperature. Thus,
combination of the styryl fragment with ionophoric moiety being
selective recognizer and trigger of hopping proton transfer in E-6
molecules has resulted in a possibility to carry out two simulta-
neous processes: ESIPT-luminescence and photoisomerization in
solutions. The effectiveness of proton transfer from the phenolic
moiety and, correspondently, ESIPT-luminescence of solutions E-6
as well as E-Z-E photo/thermal isomerization of quinazolinones E-6
canberegulatedbyvaryingof thebasicityandacidityofmedia,orby
changed concentration of alkali metal salts. As a whole, the data
obtained allow us to consider these compounds as potential
components for supramolecular ionic devices and white light-
emitting organic materials [27] in the field of molecular ionics [30].
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