title: Facile access to extremely efficient energy-transfer pairs via an unexpected reaction of squaraines with ketones.
abstract: We have discovered that squaraine NCSQ easily react with ketones in the presence of ammonium acetate to form a novel type of squaraine CCSQ. It is interesting to find that NCSQs exhibit unusual solid-state fluorescence, whereas CCSQs only exhibit fluorescence in solution. The quantum yield of solid NCSQ-g is measured to be 0.36, which is the highest among solid squaraines found so far. The large spectral overlap between the emission of NCSQs and the absorption of CCSQs, and the structural similarity of these molecules make them excellent energy-transfer (ET) pairs, as exemplified by the ET pair of CCSQ-1/NCSQ-g. When a very small amount (0.05 mol%) of CCSQ-g is doped into NCSQ-g, the ET efficiency reaches up to 96%. The Stern-Volmer quenching constant K(SV) is calculated to be 65 800, indicating that CCSQ-1/NCSQ-g forms an extremely efficient ET pair. This study provides a novel skeleton and a facile route to efficient ET pairs.
authors: Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu 610064, P.R. China.
authors: Shuaijun
authors: S
authors: Yang
authors: Jingsong
authors: J
authors: You
authors: Jingbo
authors: J
authors: Lan
authors: Ge
authors: G
authors: Gao
mesh_terms: D000085:Acetates / Q000737:chemistry; D003460:Crystallization; D003503:Cyclobutanes / Q000737:chemistry*; D004735:Energy Transfer; D005456:Fluorescent Dyes / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*
chemical_list: D000085:Acetates; D003503:Cyclobutanes; D005456:Fluorescent Dyes; D007659:Ketones; D010636:Phenols; C480596:squaraine; C018824:ammonium acetate