Synthesis of coumarin/phenanthridine-fused heterocycles and their photochemical and thermochromic properties.

Four coumarin and phenanthridine-fused heterocycles were efficiently synthesized using base-mediated annulation of N-alkylquinolinium iodide and coumarin as a key step. One compound is found to be sensitive to light and changes color upon UV irradiation; the others are sensitive to heat and possess negative thermochromic properties. A novel light- and heat-sensitive molecular skeleton is introduced.