Synthesis of Dipolar Chromophores Based on Polyfluorinated Triphenyl-4,5-dihydro-1H-pyrazoles and Dicyanoisophorone with a Thiophene Fragment in the Polymethine Chain

A series of donor–acceptor polymethine dyes containing a polyfluorinated triphenyl-4,5-dihydro-1H-pyrazole fragment as donor moiety, dicyanoisophorone fragment as acceptor moiety, and polymethine chain including a thiophene fragment have been synthesized as potential nonlinear optical chromophores. The electronic absorption spectra of the synthesized dyes showed a long-wavelength maximum at λ 540–550 nm, which is shifted by 40 nm to the red region compared to their analogues without a thiophene bridge. The dyes displayed luminescence in chloroform solution with an emission maximum at λ 740–760 nm and a Stokes shift of 200–210 nm (5000 cm^–1).