Fluorescence of molecular composites that consist of nematic liquid crystal and merocyanins

Abstract

Background: Considered merocyanine molecules have donor D and acceptor A moieties connected by polymer chain. The conjugated donor D and acceptor A parts of merocyanine molecules are planar in the ground state. The D-7t-A molecular complexes can change their conformations in an excited state due to cis-trans-conformational transitions. The viscosity' of the solvent affects conformational changes, photoluminescence (PL) decay and PL lifetime. Therefore the PL of merocyanine molecules strongly depends on medium in excited and ground states. A nematic liquid crystal was utilized as a solvent for merocyanine molecules shice it is characterized by long range order, orientates merocyanine molecules along its axis and is sensitive to external electro-magnetic field. The molecules with conjugated donor D and acceptor A parts are promising for molecular electronics (instruments for recording and processing information), optoelectronics (laser teclmologies) and biological research (fluorescent probes like prominent thioflavin T). since their PL essentially depends on the nature of the environment.