Synthesis of amphiphilic thiatrimethinecyanines

Article abstract of DOI:10.1023/B:RUJO.0000034946.67023.70

Preparation conditions were optimized for 2-methyl-5-chlorobenzothiazolium quaternary salts with long-chain N-alkyl substituents (C₁₂H ₂₅, C₁₅H₃₁, C₁₈H₃₇). They were used in the synthesis of thiatrimethinecyanines conteining in the meso-position phenyl, p-chlorophenyl, or p-fluorophenyl groups.

Full text of DOI:10.1023/B:RUJO.0000034946.67023.70

Russian Journal of Organic Chemistry, Vol. 40, No. 2, 2004, pp. 228-231. Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 2, 2004,
pp. 256-260.
Original Russian Text Copyright Ó 2004 by Orlova, Kolchina, Shakirov, Gerasimova, Shelkovnikov.
.
.
Synthesis ofAmphiphilic Thiatrimethinecyanines
N.A. Orlova, E.F. Kolchina, M.M. Shakirov, T.N. Gerasimova*, and V.V. Shelkovnikov
Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Division,
Russian Academy of Sciences, Novosibirsk, 630090 Russia
fax: (3832) 344752 e-mail: vsh@nioch.nsc.ru
Received July 24, 2003
Abstract—Preparation conditions were optimized for 2-methyl-5-chlorobenzothiazolium quaternary salts with
long-chain N-alkyl substituents (C H , C H , C H ). They were used in the synthesis of thiatrimethinecyanines
1
2
25
15 31
18 37
conteining in the meso-position phenyl, p-chlorophenyl, or p-fluorophenyl groups.
Organized molecular ensembles of organic compounds
found application in the modern systems for information
recording and processing[1].An important place among
them belongs to J-aggregates of polymethine dyes [2].
Recently high values of nonlinear cubic susceptibility were
discovered in thin films of J-aggregates of 2,2'-quino-
monomethinecyanines prepared without application of
stabilizing polymers and without using Lengmuir-Blodgett
technique [3]. The necessary condition of this aggregation
is an amphiphilic character of the molecules imparted by
long alkyl substituents at the heterocyclic nitrogen atoms.
In order to get additional data on the effect of the dye
structure on the aggregation and film-forming properties
we undertook in this study a synthesis of amphiphilic
thiatrimethinecyanines of a general formula I.
substituted 2-methylbenzothiazole II for certain data ex-
isted [5] showing that the presence of chlorine in the
5,5'-positions of a thiamonomethinecyanine molecule fa-
vored the J-aggregation.
We formerly [6] showed the possibility of J-aggreg-
ation for dye Ic obtained in a low yield by N-alkylation
of compound II with octadecyl p-chlorobenzene-
sulfonate followed by condensation of intermediately
arising quaternary salt with trimethyl orthobenzoate by
procedure [7]. In this study we performed the stage-
by-stage investigation of the synthesis of dyes I using
1
the high-resolution H NMR spectroscopy as described
in [4] for the preparation of amphiphilic 2,2'-quinomono-
methinecyanines. The analysis of reaction mixtures
obtained from compound II and p-chlorobenzene-
sulfonates synthesized by procedure [7] of general
formula C H OSO C H Cl-p [(III): n = 12 (a), n =
The presence in the molecule of dyes I of a trimethine
chain results in the absorption shift to longer waves region
compared to 2,2'-quinomonomethinecyanines [4], and the
aryl substituents in the meso-position permit a variation
of the electronic effect on the external polymethine chain.
We selected as the initial heterocycle 5-chloro-
;
n
2n+1
2
6
4
15 (b), n = 18 (c)] in the process carried out at 130–
160°C (Table 1) demonstrated that the reaction proceeded
similarly to that of 2-methyl-quinoline [4]. A typical
composition of the reaction mixture obtained by heating
benzothiazole II with sulfonic ester III is presented on
the scheme.
P
In the reaction mixture besides quaternary salt IV
were identified initial compounds II and III, 2-methyl-5-
chlorobenzothiazole p-chlorobenzenesulfonate V, and also,
as expected [4], the products of side transformations VI
and VII of the initial sulfonic ester. The optimum
composition of reaction mixtures in all cases was attained
at 150°C, and the content of the target products IVa–
IVc did not exceed 50%. It is presumable (cf. [4]) that
the alkylation efficiency of initial heterocyclic compounds
II is reduced by competing conversions of carbocations
R
ꢁ
ꢂ
ꢀ
6
6
D
1
1
&
O
&O
,
$ON
$ON
,D ,L
X = H, Alk = C H (a), C H (b), C H (c); X = Cl, Alk =
1
2
21
15 31
18 37
C H (d), C H (e), C H (f); X = F, Alk = C H (g),
1
2
21
15 31
18 37
12 21
C H (h), C H (i).
1
5
31
18 37
1070-4280/04/4002-0228Ó2004 MAIK “Nauka/Interperiodica”

2
29
SYNTHESIS OF AMPHIPHILIC THIATRIMETHINECYANINES
Table 1. Composition of reaction mixtures obtained in reaction of benzothiazole II with p-chlorobenzenesulfonates IIIa–IIIc
1
a
(
according to H NMR data) II + IIIa–c’II + IIIa-c + IVa-c + V + VIa-c + VIIa-c
5HDFWLRQꢁ
&RQWHQWꢀꢁꢂꢁ
WHPSHUDWXUHꢀꢁꢁ
,
,ꢀ
,,, ±,,,Fꢀ
Eꢁ Fꢁ
,9 ±,9Fꢀ
9ꢀ
9, ±9,Fꢀ
9,, ±9,,Fꢁ
Eꢁ Fꢁ
ꢇꢁ ꢇꢁ
ꢇꢁ !ꢇꢁ
ꢇꢁ ꢃꢅꢁ ꢃꢅꢁ
ꢇꢁ ꢈꢁꢇꢁ ꢃꢅꢁ ꢃꢅꢁ ꢃꢅꢁ
q ꢁ
ꢁ
ꢁ
Eꢁ
Fꢁ
ꢁ
ꢁ
Eꢁ
Fꢁ
ꢁ
Eꢁ
Fꢁ
ꢁ
Eꢁ
Fꢁ
ꢁ
ꢃꢄꢅꢁ
ꢃꢉꢅꢁ
ꢄꢅꢁ ꢄꢅꢁ ꢄꢅꢁ ꢆꢇꢁ ꢄꢅꢁ ꢄꢇꢁ ꢆꢇꢁ ꢆꢅꢁ ꢆꢅꢁ ꢃꢇꢁ
ꢆꢅꢁ ꢉꢅꢁ ꢆꢅꢁ ꢃꢅꢁ ꢆꢅꢁ ꢄꢅꢁ ꢉꢅꢁ ꢆꢇꢁ ꢄꢅꢁ ꢆꢅꢁ
ꢃꢅꢁ ꢃꢅꢁ ꢈꢁꢇꢁ
ꢇꢁ ±ꢁ ꢈꢁꢇꢁ
ꢇꢁ ꢃꢅꢁ
ꢇꢁ
ꢇꢁ !ꢇꢁ
ꢇꢁ
ꢇꢁ ±ꢁ
ꢇꢁ
ꢃꢇꢅꢁ
ꢇꢁ ꢇꢁ ꢆꢅꢁ ꢇꢁ
±ꢁ ±ꢁ ꢃꢇꢁ ±ꢁ
±ꢁ
±ꢁ
ꢆꢅꢁ ꢇꢅꢁ ꢉꢇꢁ ꢄꢇꢁ ꢄꢅꢁ
ꢆꢇꢁ ꢇꢅꢁ ꢉꢅꢁ ꢄꢇꢁ ꢄꢅꢁ
ꢄꢅꢁ ꢃꢅꢁ
ꢄꢅꢁ ꢃꢇꢁ
ꢇꢁ
ꢃꢊꢅ ꢁ
a
ꢁ
The data are given with an accuracy of 5%. The overall content of compounds listed in the Table is taken for 100%. The presence of
unidentified impurities is not excluded. A signal with a chemical shift of ~5.4 ppm and multiplicity of additional signals suggest formation
of alkenes (A) with an internal double bond; the mixture “b” may contain ~15% of alkene (A).
arising intermediately from sulfonic esters III under the
EXPERIMENTAL
reaction conditions.
1H NMR spectra were recorded on spectrometers
Bruker DRX-500 andAC-200 from solutions in CDCl3.
Chemical shifts are reported in the d scale. Electron
absorption spectra are registered on spectrophotometer
Quaternary salts IVa–IVc were isolated in 26–39%
yield by washing the mixtures in succession with ethyl
ether and acetonitrile. Their composition and structure
1
was proved by elemental analysis and H NMR spectra.
HÐ-8453 from solutions in CHCl (longwave absorption
3
Dyes Ia–f were prepared by boiling in pyridine salts
IVa–IVc with trimethyl orthobenzoate, ortho(p-chloro-
benzoate), and ortho(p-fluorobenzoate) VIIIa–VIIIc
obtained from the corresponding benzotrichlorides [8].
Yields of the dyes after isolation from the mixture and
purification attained 10–28%. We failed to increase the
yield by carrying out the synthesis in DMSO instead of
pyridine that had brought the success in [4]. The
composition and structure of dyes was proved by
maxima are reported).
The column chromatography was performed on
alumina of the II activity grade. For solvent mixtures used
as eluents the volume ratios are given.
Synthesis of 2-methyl-3-alkyl-5-chlorobenzo-
thiazolium p-chlorobenzenesulfonates (IVa–c). A
mixture of 5 mmol of 2-methyl-5-chlorobenzothiazole II
[11] and 5 mmol of the respective alkyl-p-chlorobenzene-
1
sulfonate III was heated for 5 h under conditions indicated
in Table 1. The reaction mixtures were analyzed by H
NMR spectroscopy (cf. [4]). The composition of mixtures
is ccompiled in Table 1.
elemental analysis and H NMR spectra (Tables 2 and
1
3
). Electron absorption spectra of the dyes in CHCl are
3
identical and virtually coincide with the spectrum of their
N,N’-diethyl-substituted analog [9].As should be expected
[
10], the length of N-alkyl group does not affect the dye
On cooling the solidified reaction product was ground
absorption in the monomer state.
with Et O, the precipitate was filtered off and washed in
2
Scheme.
6
&+ ꢀꢀꢁꢀꢀQꢂ&O& + 62 2& +
1
&O
,
,
,,,D
6
6
ꢃꢄꢅ &
&
+ ꢁ
&+ ꢀꢀꢁꢀꢀꢆ& + ꢇ 2ꢀꢀꢁꢀꢀ&+ &+& +
1
1
&O
&O
Qꢂ&O& + 62 & +
Qꢂ&O& + 62 +
,9D
9
9,D
9,,D
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 40 No. 2 2004

230
ORLOVA et al.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 40 No. 2 2004

2
31
SYNTHESIS OF AMPHIPHILIC THIATRIMETHINECYANINES
succession with Et O and MeCN. The residue was
recrystallized from MeCN. Yields obtained under
The study was carried out under financial support of
the Russian Foundation for Basic Researc (grant 02-
2
optimum conditions (at 150°C), melting points, and 03-33336) NOW grant 047.009.019.
elemental analyses of benzothiazolium salts IVa–IVc are
given in Table 2, H NMR spectra in Table 3.
1
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2
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4
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6
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4
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2
2
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~
2
2
The extract was washed with 2% HCl and with water,
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(
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2
3
J. Phys. Chem., 1985, vol. 89, p. 560.
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2
2
1
0.Shelkovnikov, V.V., Ivanova, Z.M., Orlova, N.A.,
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4
:1). The solution was evaporated, the residue was
dissolved in CH Cl and precipitated with Et O. The
2
2
2
relatively less stable dyes If, Ig were prepared by boiling
for 45 min and were subjected only once to chromato-
graphy.
1
1. Formina, L.V. and Lyubich, M.S., Tekhnologiya
registriruyushchikh sred (Technology of Registering
Media), 1989, p. 46.
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