4-{3,5-Bis[2,3,5,6-tetrafluoro-4-(piperazin-1-yl)phenyl]-4,5-dihydro-1H-pyrazol-1-yl}benzaldehyde in the Synthesis of New Dendritic Chromophores

The reaction of 4-[3,5-bis(2,3,5,6-tetrafluorophenyl)-4,5-dihydro-1H-pyrazol-1-yl]benzaldehyde with tert-butyl piperazine-1-carboxylate gave Boc-protected 4-{3,5-bis[2,3,5,6-tetrafluoro-4-(piperazin-1-yl)-phenyl]-4,5-dihydro-1H-pyrazol-1-yl}benzaldehyde. The latter reacted as a donor block with dicyanoisophorone as an acceptor block in butan-1-ol in the presence of morpholine to produce a dipolar dye with Boc-protected piperazine fragments. After removal of the Boc protection by the action of HCl, the resulting bis-piperazinium dihydrochloride was acylated with benzoyl chloride and its branched derivatives to afford new dipolar chromophores.