Abstract Cyanine dyes (1a–d) with the 5, 5′, 6, 6′-tetrachloro-1, 1′-dialkyl-3, 3′-di-(3- carboxypropyl)-benzimidocarbocyanine chromophore differing only in the chain length of their alkyl groups in 1, 1′-position have been synthesized, spectroscopically characterized, and compared with 5, 5′ 6, 6′-tetrachloro-1, 1′-diethyl-3, 3′-di-(4-sulfobutyl)- benzimidocarbocyanine (TDBC). In aqueous solution the dyes form J-aggregates which, ...
