Aggregation-Induced Emission and Sensing Characteristics of Triarylborane-Oligothiophene-Dicyanovinyl Triads

The design, synthesis and aggregation-induced emission properties of a new series of triarylborane-oligothiophene-dicyanovinyl (DCV) conjugates 4-6 (A-D-A' type molecular configuration) are reported. The optical properties of 4-6 can be modulated by judiciously varying the number of thiophene units between electron deficient boryl and dicyanovinyl units. Compound 6 with terthiophene spacer showed highly red-shifted absorption and emission compared to 5 and 4 with bithiophene and monothiophene spacers, respectively. Compounds 5 and 6 show aggregation-induced emission enhancement in water/THF mixtures. Compounds 5 and 6 also showed solvent viscosity dependent emission characteristics. All the three compounds show distinct optical responses for small anions such as fluoride and cyanide. Filter paper strips coated with compounds 5 and 6 can detect F- and CN- in aqueous media with different colorimetric responses.