Synthesis and Absorption Spectral Properties of New Merocyanine Dyes Derived from 1,1 Diaryl-2-propyn-1-ols

Abstract A series of push-pull butadiene dyes (new merocyanine dyes) containing 3,6-bis(dimethylamino)fluorenylidene, thioxanthenylidene, or 10-(9-xanthenylidene)-9(10H)-anthrylidene chromophore was easily synthesized from the corresponding 1,1-diaryl-2-propyn-1-ol systems. Their absorption spectral properties were examined and the relationship between their light absorption properties and chemical structures is discussed in comparison with the results from PPP-SCF-CI-MO calculations. The influence of the solvent polarity on the 1⁄λmax(=wave number)-values of the dyes was investigated, and the solvatochromic nature compared with the known solvent polarity parameters such as ET30, Z, χR, πazo* on 2-[2-[3,6-bis(dimethylamino)fluorenylidene]ethylidene]-1,3-indandione.