Photoluminescent divinylbipyrroles were synthesized from 3,3′,4,4′-tetraetyl-2,2′-bipyrrole-5,5′-dicarboxaldehyde and activated methylene compounds via aldol condensation.For mechanistic clarity, molecular structures of Meldrum’s acid- and 1,3-dimethylbarbituricacid-derived divinylbipyrroles were determined by single-crystal X-ray diffraction. Photoluminescentproperties of the synthesized divinylbipyrroles in dichloromethane were found to be dependent onthe presence of electron withdrawing groups at the vinylic terminal. The divinylbipyrroles derivedfrom malononitrile, Meldrum’s acid, and 1,3-dimethylbarbituric acid showed fluorescent peaks at553, 576, and 602 nm respectively. Computational studies indicated that the alkyl substituents on thebipyrrole 3 and 3′positions increased energy level of the highest occupied molecular orbital (HOMO)compared to the unsubstituted derivatives and provided rationale for the bathochromic shift of theultraviolet-visible (UV-Vis) spectra compared to the previously reported analogs.
Okawara, Toru; Kawano, Reo; Morita, Hiroya; Finkelstein, Alan; Toyofuku, Renjiro; Matsumoto, Kanako; Takehara, Kenji; Nagamura, Toshihiko; Iwasa, Seiji; and Kumar, Sanjai, "Synthesis, Crystal Structure, and Photoluminescent Properties of 3,3′,4,4′-Tetraethyl-5,5′-divinyl-2,2′-bipyrrole Derivatives" (2017). CUNY Academic Works.