ESIPT fluorescent dyes with adjustable optical properties: Substituent and conjugation effects

摘要: Abstract Based on the design and synthesis of 10-hydroxybenzo[h]quinoline (3) derivatives, we demonstrate a prototypical system to investigate both substituent conjugation effects excited-state intramolecular proton transfer emission through combination experimental theoretical studies. On one hand, adding an electron-withdrawing at phenol ring in 3 results decrease HOMO, hence, increase energy gap keto-tautomer (o-4 p-4). An opposite effect is observed when electron-donating added (1). other elongation p-conjugation length by installed 2-methylenemalononitrile group (o-2 p-2) induces further π-electron delocalization, thus smaller gap. Time-dependent density functional theory calculations these dyes are reported order rationalize their electronic structure optical properties.