1070-4272/03/7604-0582 $25.00 C 2003 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 76, No. 4, 2003, pp. 582!584. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 4, 2003,
Original Russian Text Copyright + 2003 by Salimgareeva, Ostakhov, Ponomareva, Kolesov, Leplyanin.
AND INDUSTRIAL ORGANIC CHEMISTRY
Absorption and Luminescence Spectra
V. N. Salimgareeva, S. S. Ostakhov, V. A. Ponomareva, S. V. Kolesov, and G. V. Leplyanin
Institute of Organic Chemistry, Ufa Scientific Center, Russian Academy of Sciences, Ufa, Bashkortostan, Russia
Received January 22, 2003
Abstract-Electronic absorption and luminescence spectra of cyclic dimer of a-methylstyrene, 1,1,3-tri-
methyl-3-phenylindan, were described. The quantum yield and lifetime of fluorescence were determined.
It is well known that certain individual and sub-
stituted hydrocarbons, whose molecules contain rings
and conjugated double bonds, are capable of light
emission, i.e., they luminesce when exposed to high-
energy radiation . Such compounds are distin-
guished by a rigid molecular structure precluding free
rotation of molecular segments, thus decreasing the
probability of nonradiative transitions.
Among the compounds of interest are aromatic
polycyclic hydrocarbons (naphthalene, anthracene,
naphthacene, phenanthrene, etc.), aromatic chain com-
pounds (polyphenylenes, stilbene, diphenylpolyenes,
aryldivinylbenzenes, etc.) . In the molecules of
luminescent compounds, the ordinary bond is located
between two double bonds or between a multiple
bond and an atom having unshared p-electron pair.
This applies to, e.g., nitrogen- and oxygen-contain-
ing heterocyclic compounds (aryloxazoles, aryloxadi-
Chain aromatic compounds exhibit luminescence in
the case when conjugation in the molecule is disturbed
by methylene groups inserted between the benzene
rings like, e.g., in diphenylmethane or dibenzyl .
The absorption and emission spectra of compounds
with Ph3X3Ph structure are close to those of the cor-
responding benzene derivatives.
It was of interest to study the optical properties of
an aromatic compound whose molecule contains an X
group rigidly linked to one of the benzene rings.
An example of such a compound is 1,1,3-trimethyl-3-
phenylindan (TMPI) yielded by cyclodimerization of
a-methylstyrene . It was termed [crystalline dimer
of a-methylstyrene.] This is an aromatic hydrocarbon
of the following structure
Owing to its p-electron system, TMPI is capable
of fluorescence and/or intermolecular energy transfer.
Linear oligomers of a-methylstyrene, prepared by its
cationic polymerization, exhibit fluorescence at 2703
310 nm with emission peak at 285 nm . As far as
we know, the luminescence properties of cyclic di-
mers of a-methylstyrene have not been studied pre-
A great number of luminescent compounds have
been proposed recently, but a search for new lumi-
nophores with fast luminescence response and high
quantum yield for designing scintillators is still a top-
ical task. Candidate scintillators or luminescent addi-
tives for liquid or plastic scintillators must exhibit high
thermal and chemical resistance and radiation hard-
ness. This is characteristic specifically of TMPI [8, 9].
The electronic structure of the TMPI molecule
composed of phenyl and indan rings must be inter-
mediate between the conjugated (biphenyl) and non-
conjugated (diphenylmethane) structures. Similarly to
diphenylmethane, conjugation in the TMPI molecule
is disturbed but, unlike diphenylmethane, the central
carbon atom in the TMPI molecule is involved in the
five-membered ring of the indan moiety. This must
increase to a certain extent the rigidity of its structure,
making it more similar to that of biphenyl. Also,
the interest in TMPI is due to the possibility of pre-
paring high-purity (up to 99.99%) TMPI in high yield
(over 96%), as well as to its good solubility in many
organic solvents and polymers (up to 60 wt %).