Sumitomo Seika Chemicals Co., Ltd.

Tdk Corporation

Satoshi Kimura

Hiroshi Goda

Michio Suzuki

Naohiro Yoshikawa

Nario Kimura

Masaki Teramoto

Yuuji Matuzaki

Kazuyoshi Hirako

Yoshihide Masuda

Masahiro Shinkai

Kenryo Namba

Sumiko Kitagawa

The cyanine dyes of the invention are well soluble in solvents having a high evaporation rate and stable against light, and thus effective for improving productivity and realizing optical recording media, especially CD-R and DVD-R optical discs, having improved light resistance. The optical recording medium of the invention uses a photo-stabilized cyanine dye which is obtained as a counter ion bonded compound between an anion of the formula (1) and a cation of the formula (2): ##STR1## wherein R.sub.01 and R.sub.02 each are ##STR2## wherein each of R.sub.11 and R.sub.12 is an alkyl group of 1 to 4 carbon atoms or phenyl group, ##STR3## wherein m is equal to 3, 4, 5 or 6, ##STR4## or phenyl groups; M is a transition metal; each of Z.sub.1 and Z.sub.2 is a fused benzene ring or fused naphthalene ring; each of R.sub.21 and R.sub.22 is an alkyl group; and n is equal to 0, 1 or 2.

Photo-stabilized cyanine dyes and optical recording media

A novel substituted benzenedithiol metal complex represented by the general formula (1) is provided. The substituted benzenedithiol metal complex is useful as a singlet oxygen quencher and as an optical data recording medium per se. ##STR1## wherein M is a transition metal; A.sup.+ is a quaternary ammonium group; and R is an organic group selected from the group consisting of organic groups represented by the formulae (i), (ii), (iii) and (iv): ##STR2## (wherein R.sup.1 is an alkyl group having 1 to 4 carbon atoms) ##STR3## (wherein n is 3, 4 or 5), ##STR4## (wherein R.sup.2 is one of a hydrogen atom and a substitutent having 1 to 4 carbon atoms).

Substituted benzenedithiol metal complex

A method of producing a dibenzoxazolyl thiophene represented by the formula ##STR1## wherein R'' represents a hydrogen, an alkyl of 1-8 carbons, a cycloalkyl, a phenyl, a substituted phenyl or a benzyl, which includes: reacting a thiophene-2,5-dicarboxylic acid diester represented by the formula ##STR2## wherein R' represents a branched alkyl of 3-5 carbons, phenyl, or tolyl, with an aminophenol represented by the formula ##STR3## wherein R'' is the same as before, in the presence of an acid catalyst, wherein the acid catalyst is boric acid, phosphoric acid, polyphosphoric acid, zinc chloride, ferric chloride, or sulfuric acid.

Production of thiophene-2,5-dicarboxylic acid diesters,

There is disclosed a method of producing a thiophene-2,5-dicarboxylic acid diester represented by the formula ##STR1## wherein R' represents an alkyl of 1-8 carbons, a phenyl, a substituted phenyl or benzyl, which comprises:

Production of dibenzoxazolylthiophenes

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Hyogo, Japan

Satoshi Kimura