Synthesis and characterization of emissive 1,9,10-anthyridine derivatives with donor and acceptor groups

Abstract

Push–pull-type emissive 1,9,10-anthyridine derivatives incorporating bis-trifluoromethyl and amino (hydroxy) groups were designed and synthesized through the ring expansion of 1,8-naphthyridine. The X-ray crystallographic analysis of the single crystals of these 1,9,10-anthyridine derivatives, termed “TANA,” revealed the formation of intermolecular hydrogen-bonded complexes or hydration complexes. These TANA derivatives exhibited fluorescence solvatochromic properties and emitted at longer wavelengths compared to 1,8-naphthyridine, despite possessing analogous bis-trifluoromethyl and amino groups. Furthermore, NMR titration experiments revealed that TANA, characterized by an ensemble of three hydrogen-bond acceptors, is capable of forming hydrogen-bonded complexes with protonated diaminopyridine, which contains an array of three hydrogen-bond donors. Therefore, TANA derivatives are excellent fluorescent materials with molecular recognition abilities.