New excited state intramolecular proton transfer (ESIPT) dyes based on naphthalimide and observation of long-lived triplet excited states

A new excited state intramolecular proton transfer chromophore of naphthalimide (NI) conjugated 2-(2-hydroxyphenyl) benzothiazole (HBT) was prepared which shows red shifted absorption and long-lived triplet excited states.