Photo- and ionochromic indoline spiropyrans based on 7,8-dihydroxy-4- methyl-2-oxo-2H-chromene-6-carbaldehyde

Article abstract of DOI:10.1134/S1070428011090193

A number of indoline spiropyrans were synthesized from 7,8-dihydroxy-4- methyl-2-oxo-2Hchromene-6-carbaldehyde. The products were found to exhibit both photochromic and ionochromic properties. According to the UV, IR, and ¹H NMR spectral data,

Full text of DOI:10.1134/S1070428011090193

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2011, Vol. 47, No. 9, pp. 1370–1374. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © O.G. Nikolaeva, O.Yu. Kostyrina, E.N. Shepelenko, A.V. Tsukanov, A.V. Metelitsa, G.S. Borodkin, A.D. Dubonosov, V.A. Bren’,
V.I. Minkin, 2011, published in Zhurnal Organicheskoi Khimii, 2011, Vol. 47, No. 9, pp. 1348–1352.
Photo- and Ionochromic Indoline Spiropyrans
Based on 7,8-Dihydroxy-4-methyl-2-oxo-2H-chromene-
6-carbaldehyde
O. G. Nikolaevaa, O. Yu. Kostyrinaa, E. N. Shepelenkob, A. V. Tsukanovb, A. V. Metelitsaa,
G. S. Borodkina, A. D. Dubonosovb, V. A. Bren’a, and V. I. Minkina,b
a Research Institute of Physical and Organic Chemistry, Southern Federal University,
pr. Stachki 194/2, Rostov-on-Don, 344090, Russia
e-mail: aled@ipoc.rsu.ru
b Southern Research Center, Russian Academy of Sciences, Rostov-on-Don, Russia
Received February 14, 2011
Abstract—A number of indoline spiropyrans were synthesized from 7,8-dihydroxy-4-methyl-2-oxo-2H-
chromene-6-carbaldehyde. The products were found to exhibit both photochromic and ionochromic properties.
1
According to the UV, IR, and H NMR spectral data, they exist in the spiro form. Irradiation at λ 365 nm in
2-methylbutane–propan-2-ol (4:1) at 203 K induces their isomerization into colored merocyanine structure.
Addition of alkaline earth and transition metal salts to acetonitrile solutions of these compounds at room
temperature changes the isomer ratio and leads to formation of merocyanine complexes characterized by
different colors, so that visual detection of Zn2+, Mg2+, Hg2+, and Pb2+ ions is possible.
DOI: 10.1134/S1070428011090193
Photochromic spiropyrans exhibiting ionochromic
properties attract interest from the viewpoint of their
use as photodynamic chemosensors, photoswitches,
and materials for data recording and storage [1–5]. We
have continued studies on spiropyrans having a fused
coumarin fragment as a part of the 2H-chromene
moiety [6–9]. In the present article we describe the
synthesis and properties of spiropyrans possessing
an additional ligand center, hydroxy group in position
10 of the pyranochromene fragment.
chlorates in the presence of triethylamine gave the
corresponding spiropyrans IIa–IIe (Scheme 1). The IR
spectra of IIa–IIe contained absorption bands typical
of C=C bond in the pyran ring (1600–1620 cm–1),
carbonyl group in the coumarin fragment (1690–
1725 cm–1), and hydroxy group (3320–3370 cm–1). In
1
the upfield region of the H NMR spectra of IIa–IIe
we observed two signals from magnetically nonequiv-
alent methyl groups at δ 1.14–1.34 ppm. Signals from
diastereotopic methylene protons in the N-benzyl sub-
stituent of compound IIb appeared as an AB quartet
(two doublets at δ 4.25 and 4.58 ppm with a coupling
7,8-Dihydroxy-4-methyl-2-oxo-2H-chromene-6-
carbaldehyde (I) was synthesized according to the
procedure reported in [10]. Condensation of aldehyde I
with N-substituted 2,3,3-trimethyl-3H-indol-1-ium per-
2
constant J of 16.50 Hz). Diastereotopic protons in the
methyl groups of the N-isopropyl substituent of IIc
Scheme 1.
Me
O
Me
Me
Me
4'
5'
Me
7'
OCH
Me
3'
+
Me
ClO4
O
O
N
HO
O
O
N
OH
R
R
OH
I
IIa–IIe
R = Me (a), PhCH2 (b), i-Pr (c), C6H13 (d), C8H17 (e).
1370

PHOTO- AND IONOCHROMIC INDOLINE SPIROPYRANS
1371
Table 1. Electronic absorption spectra of spiropyrans IIa–
IIe in 2-methylbutane–propan-2-ol (4:1) at 203 K
resonated as two doublets (AB quartet) at δ 1.33 and
1.39 ppm with a coupling constant J of 6.95 Hz.
3
These findings indicated cyclic structure of the con-
densation products. The 7-H proton resonated as a sin-
glet at δ 6.12–6.13 ppm, protons in the 6-methyl group
gave a singlet at δ 2.38–2.39 ppm, and signal from the
10-OH proton was located at δ 5.45–5.60 ppm.
Cyclic form A,
λmax, nm
Photoinduced form B,
λmax, nm
Comp. no.
IIa
IIb
IIc
IId
IIe
340
335
330
332
335
445, 580
460, 609
450, 590
458, 603
455, 602
Compounds IIa–IIe displayed in the electronic
absorption spectra (2-methylbutane–propan-2-ol, 4:1,
203 K) a long-wave band at λmax 332–340 nm with
clearly defined vibrational structure, which is typical
of cyclic isomers IIA (Scheme 2, Table 1) [1, 2, 11]. It
is known that the long-wave maximum in electronic
absorption spectra of spiropyrans corresponds to
photochemically active coumarin fragment and that the
maximum located at shorter wavelength corresponds to
absorption of the indoline fragment [11].
sitions, respectively, in open merocyanine isomer B
(Scheme 2, Table 1) [2, 11].
Addition of an equivalent amount of Zn2+, Cd2+,
Ba2+, Co2+, Ni2+, Hg2+, or Pb2+ acetate or Mg2+ or Ca2+
perchlorate to a solution of compound II in acetonitrile
resulted in essential variation of the electronic absorp-
tion spectra due to formation of complex C with the
merocyanine isomer. Complexes like IIC were report-
ed by us previously [12]. The presence of OH group
therein follows from insignificant change of the cor-
responding absorption band in the IR spectra. In the
electronic absorption spectra we observed small in-
Irradiation of solutions of compounds II at a wave-
length corresponding to long-wave absorption of cyclic
structure A leads to coloration due to appearance of
two new structured bands in the visible region with
their maxima at λ 445–460 (λ1) and 580–652 nm (λ2);
these bands originate from the S0→S2 and S0→S1 tran-
Table 2. Parameters of the electronic absorption spectra of spiropyrans IIa–IIc and IIe and their complexes with metal ions
(M2+) in acetonitrile at 293 K
Comp.
no.
Absorption,
λmax, nm
Blue or red shift, Comp.
Absorption,
λmax, nm
Blue or red shift,
Metal
Metal
Δλmax, nm
no.
Δλmax, nm
IIa
–
467, 595
444, 540
417, 524
427
IIc
Mg
Cd
Ca
Co
Ni
417, 529
443, 576
434, 520
455, 547
467
–28, –59
–26, –12
–11, –68
+10, –41
+22
Zn
Mg
Cd
Ca
Ba
Pb
–
–23, –55
–50, –71
–40
419, 538
420
–48, –57
–40
Hg
Pb
–
468
+23
460, 566
449, 587
452, 562
457, 561
444, 560
475
0–6, –29
460, 556
442, 603
443, 551
421, 524
426, 542
433, 577
466, 593
471, 595
470
+15
IIb
IIe
Zn
Mg
Ca
Co
Ni
Hg
Pb
–
0+3, –25
0+8, –26
0–5, –27
+26
Zn
Mg
Ca
Ba
Co
Ni
0+1, –52
–21, –79
–12, –61
0–9, –26
+16, –10
+29, –80
+29
487, 625
470
+38, +38
+21
470, 570
445, 588
442, 547
+21, –17
Hg
Pb
IIc
459, 562
+17, –41
Zn
0–3, –41
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 9 2011

NIKOLAEVA et al.
The reaction of spiropyrans II with metal ions is
1372
D
fairly specific. Solutions of II acquire different colors
in the presence of different metal ions, so that this
reaction may be used for qualitative detection of the
latter. With a view to study the complex formation
process with alkaline earths in more detail, 2 equiv of
magnesium perchlorate was added to a solution of
spiropyran IIa in acetonitrile-d3 in the dark, and
1H NMR spectra of the mixture were recorded in
10 min and 1 h after addition of the salt (Fig. 2).
0.6
0.4
0.2
0.0
10
6
9
8
7
1
The H NMR spectrum of IIa contained signals
5
typical of the spiro structure: two signals from magnet-
ically nonequivalent geminal methyl groups at δ 1.71
and 1.83 ppm, a signal from the NCH3 group at
δ 3.30 ppm, a doublet from the 3-H proton at
δ 6.40 ppm, and a singlet from 7-H at δ 6.62 ppm. No
signals assignable to merocyanine isomer B were
present (Fig. 2a). After addition of Mg(ClO4)2 in the
dark, doublets belonging to the CH=CH protons in the
merocyanine form appeared at δ 8.45 ppm. The inten-
sity of signals belonging to spiro isomer A decreased
approximately twofold. In addition, these signals were
displaced upfield by about 0.50 ppm relative to the
corresponding signals of IIa (Fig. 2b). These data
suggest gradual displacement of the equilibrium to-
ward merocyanine structure IIB as a result of forma-
tion of complex IIC. In 1 h after addition of magne-
sium perchlorate, signals from spirocyclic structure
IIA disappeared completely (Fig. 2c).
4
3
10
2
1
400
600
λ, nm
Fig. 1. Electronic absorption spectra of spiropyran IIa
(1) before addition of Mg(ClO4)2 and in (2) 0, (3) 5, (4) 10,
(5) 20, (6) 30, (7) 45, (8) 60, (9) 90, and (10) 120 min after
addition of Mg(ClO4)2; cIIa = 2.5×10–5, cMg = 5×10–4 M;
acetonitrile, 293 K.
crease in the intensity of absorption maxima in the
near-UV region, and new strong absorption bands ap-
peared in the visible region due to complex formation;
the position of the visible maxima depended on the
nature of metal ion (Fig. 1, Table 2).
To conclude, indoline spiropyrans II can be used as
multifunctional signaling systems due to formation of
differently colored solutions with alkaline earth and
transition metal ions.
Scheme 2.
Me
O
Me
Me
Me
Me
Me
hν1, Δ
hν2, Δ
N
R
O
O
O
O
N
O
OH
R
OH
IIA
IIB
Me
Me
Me
M2+
N
R
O
O
O
O
M
2+/n
IIC
M = Mg, Zn, Cd, Ca, Ba, Cu, Ni, Hg, Pb; n = 1, 2.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 9 2011

PHOTO- AND IONOCHROMIC INDOLINE SPIROPYRANS
EXPERIMENTAL
1373
(a)
The electronic absorption spectra were recorded on
a Varian Cary-100 spectrophotometer. Solutions of
compounds II were irradiated with a DRSh-250 mer-
cury lamp equipped with a set of light filters. The IR
spectra were measured on a Varian Excalibur spec-
trometer with Fourier transform from samples dis-
1
persed in mineral oil. The H NMR spectra were
obtained on a Varian Unity-300 instrument (300 MHz)
from solutions in CDCl3 using the residual proton
signal of the solvent as reference (CHCl3, δ 7.25 ppm).
(b)
General procedure for the synthesis of indoline
spiropyrans IIa–IIe. Triethylamine, 0.1 ml (0.7 mmol),
was added to a hot solution of 2.42 g (1.1 mmol) of
formylcoumarin I and 1 mmol of the corresponding
1-substituted 2,3,3-trimethyl-3H-indol-1-ium perchlo-
rate in propan-2-ol. The mixture was heated for 5 h
under reflux, cooled, poured into water, and extracted
with several portions of chloroform. The extracts were
combined, dried over CaCl2, and evaporated to a vol-
ume of 10–15 ml. The residue was subjected to chro-
matography on silica gel using chloroform as eluent,
and the product was additionally purified by recrystal-
lization from benzene.
(c)
10′-Hydroxy-1,3,3,6′-tetramethyl-1,3-dihydro-
8′H-spiro[indole-2,2′-pyrano[3,2-g]chromen]-8′-one
(IIa). Yield 34%, mp 205–207°C. IR spectrum, ν,
1
cm–1: 3360, 1710, 1610, 920. H NMR spectrum, δ,
ppm: 1.19 s and 1.30 s (3H each, 3-CH3), 2.39 s (3H,
6′-CH3), 2.78 s (3H, NCH3), 5.78 d (1H, 3′-H, J =
10.55 Hz), 5.60 br.s (1H, OH), 6.13 s (1H, 7′-H),
6.56 d (1H, 7-H, J = 7.62 Hz), 6.83–7.07 m (3H, 4′-H,
5-H, 5′-H), 7.09 d (1H, 4-H, J = 7.62 Hz), 7.20 t (1H,
6-H). Found, %: C 73.64; H 5.65; N 3.82. C23H21NO4.
Calculated, %: C 73.58; H 5.64; N 3.73.
8
7
6
5
4
3
2
1
δ, ppm
1
Fig. 2. H NMR spectra of compound IIa in acetonitrile-d3
(a) before addition and in (b) 10 min and (c) 1 h after ad-
dition of Mg(ClO4)2.
1-Benzyl-10′-hydroxy-3,3,6′-trimethyl-1,3-dihy-
dro-8′H-spiro[indole-2,2′-pyrano[3,2-g]chromen]-
8′-one (IIb). Yield 45%, mp 215–217°C. IR spectrum,
8′-one (IIc). Yield 48%, mp 268–269°C. IR spectrum,
1
ν, cm–1: 3350, 1720, 1620, 920. H NMR spectrum, δ,
ppm: 1.14 s and 1.27 s (3H each, 3-CH3), 1.33–1.39 q
(6H, CH3, J = 6.95 Hz), 2.38 s (3H, 6′-CH3), 3.82 m
(1H, CH), 5.56 br.s (1H, OH), 5.57 d (1H, 3′-H, J =
10.30 Hz), 6.12 s (1H, 7′-H), 6.75–7.41 m (6H, 4-H,
4′-H, 5-H, 5′-H, 6-H, 7-H). Found, %: C 74.59; H 6.39;
N 3.40. C25H25NO4. Calculated, %: C 74.72; H 6.25;
N 3.47.
1
ν, cm–1: 3370, 1720, 1620, 920. H NMR spectrum, δ,
ppm: 1.31 s and 1.34 s (3H each, 3-CH3), 2.38 s (3H,
6′-CH3), 4.25–4.58 q (2H, NCH2, J = 16.50 Hz),
5.57 br.s (1H, OH), 5.82 d (1H, 3′-H, J = 10.30 Hz),
6.13 s (1H, 7′-H), 6.46 d (1H, 7-H, J = 7.62 Hz), 6.83–
7.07 m (3H, 4′-H, 5-H, 5′-H), 7.05 d (1H, 4-H, J =
7.62 Hz), 7.10 t (1H, 6-H), 7.20–7.30 m (5H, Harom).
Found, %: C 77.5; H 5.52; N 3.19. C29H25NO4. Calcu-
lated, %: C 77.17; H 5.58; N 3.10.
1-Hexyl-10′-hydroxy-3,3,6′-trimethyl-1,3-dihy-
dro-8′H-spiro[indole-2,2′-pyrano[3,2-g]chromen]-
8′-one (IId). Yield 35%, mp 165–166°C. IR spectrum,
1
ν, cm–1: 3350, 1725, 1620, 940. H NMR spectrum, δ,
10′-Hydroxy-1-isopropyl-3,3,6′-trimethyl-1,3-di-
hydro-8′H-spiro[indole-2,2′-pyrano[3,2-g]chromen]-
ppm: 1.18–1.28 m (21H, CH3, CH2), 2.38 s (3H,
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 9 2011

NIKOLAEVA et al.
1374
3. Favaro, G., Chidichino, G., Formoso, P., Manfredi, S.,
Mazzucato, U., and Romani, A., J. Photochem. Photo-
biol. A, 2001, vol. 140, p. 229.
6′-CH3), 3.17 m (2H, NCH2), 5.57 br.s (1H, OH),
5.74 d (1H, 3′-H, J = 10.30 Hz), 6.12 s (1H, 7′-H),
6.57 d (1H, 7-H, J = 7.62 Hz), 6.80–6.95 m (3H, 4′-H,
5-H, 5′-H), 7.08 d (1H, 4-H, J = 7.62 Hz), 7.10 t (1H,
6-H). Found, %: C 78.62; H 6.99; N 3.42. C28H31NO4.
Calculated, %: C 78.34; H 7.22; N 3.26.
4. Han, S. and Chen, Y., Dyes Pigm., 2011, vol. 88, p. 235.
5. Natali, N., Soldi, G., and Giordani, S., Tetrahedron,
2010, vol. 66, p. 7612.
6. Metelitsa, A.V., Knyazhansky, M.I., Ivanitsky, V.V.,
Nikolaeva, O.G., Palchkov, V.A., Panina, A.P., Shele-
pin, N.E., and Minkin, V.I., Mol. Cryst. Liq. Cryst.,
1994, vol. 246, p. 37.
10′-Hydroxy-3,3,6′-trimethyl-1-octyl-1,3-dihy-
dro-8′H-spiro[indole-2,2′-pyrano[3,2-g]chromen]-
8′-one (IIe). Yield 27%, mp 157–158°C. IR spectrum,
1
ν, cm–1: 3320, 1690, 1600, 930. H NMR spectrum
7. Ivanitskii, V.V., Nikolaeva, O.G., Metelitsa, A.V., Vol-
bushko, N.V., Luk’yanov, B.S., Palchkov, V.A., and
Shelepin, N.E., Khim. Geterotsikl. Soedin., 1992, p. 601.
(CDCl3), δ, ppm: 0.86 t (3H, CH3), 1.19–1.29 m (14H,
3-CH3, CH2), 1.60 m (4H, CH2), 2.38 s (3H, 6′-CH3),
3.17 m (2H, NCH2), 5.45 br.s (1H, OH), 5.86 d (1H,
3′-H, J = 10.50 Hz), 6.12 s (1H, 7′-H), 6.56–7.25 m
(6H, 4-H, 4′-H, 5-H, 5′-H, 6-H, 7-H). Found, %:
C 78.52; H 7.39; N 3.22. C30H35NO4. Calculated, %:
C 78.62; H 7.96; N 3.06.
8. Nikolaeva, O.G., Gaeva, E.B., Shepelenko, E.N., Tsuka-
nov, A.V., Metelitsa, A.V., Luk’yanov, B.S., Dubono-
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Kozyrev, V.S., Metelitsa, A.V., Dubonosov, A.D.,
Bren’, V.A., and Minkin, V.I., Vestn. Yuzhn. Nauch.
Tsentra Ross. Akad. Nauk, 2010, vol. 6, no. 3, p. 12.
This study was performed under financial support
by the Ministry of Education and Science of the
Russian Federation (Federal special-purpose program
“Scientific and Scientific–Pedagogical Staff of Innova-
tion Russia 2009–2013,” state contract no. P678, May
20, 2010).
10. Naik, R.M. and Thakor, V.M., J. Org. Chem., 1957,
vol. 22, p. 1626.
11. Guglielmetti, R., Photochromism: Molecules and
Systems, Dürr, H. and Bouas-Laurent, H., Eds., Amster-
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