Effect of phenyl ring substitution on J-aggregate formation ability of novel bisazomethine dyes in vapour-deposited films

Bisazomethine dyes, which are synthesized using diaminomaleonitrile and aminobenzaldehydes, exhibit red fluorescence in solution and in the solid state. Several bisazomethine dyes are known to form J-aggregates in vapour-deposited films. In this work, novel bisazomethine dyes were synthesized and the effect of phenyl ring substitution on the J-aggregate formation in vapour-deposited films was examined. The optical properties of the dyes were examined in solution and in the solid state through molecular orbital calculations. Four derivatives were found to form J-aggregates in vapour-deposited films as determined from the shape of the spectrum and the absorption edge.

Research highlights
► Bisazomethine dyes having an alkoxy substituent on its phenyl rings were synthesized.
► We examine the effect of alkoxy substituent on the J-aggregate formation.
► Four derivatives were found to form J-aggregates in vapour-deposited films.
► The formation was characterized by the shape of an absorption band.