Uncovering and controlling the ESIPT behavior for 2,2‐dipicolylamino substituted 2‐(2’‐hydroxybenzofuranyl) benzoxazole: Solvent polarity

In view of potential applications of fluorescent probe for the novel 2,2-dipicolylamino substituted 2-(2 '-hydroxybenzofuranyl) benzoxazole (HBBODipic) dye, herein, we mainly focus on exploring effect of solvent polarity on ESIPT behavior for HBBODipoc. First, we compare the dominating atomic charge distribution, geometric parameters, and infrared (IR) vibrational behaviors of HBBODipic, and we confirm that intramolecular hydrogen bond O-H center dot center dot center dot N could be strengthened in S-1 state and nonpolar solvents are more conducive to the strengthening of hydrogen bonds. Via studying frontier molecular orbitals (MOs), we clarify that intramolecular charge transfer (ICT) occurs in excited molecule and charge redistribution facilitates ESIPT for HBBODipoc. In particular, nonpolar solvent is more propitious to ESIPT process of HBBODipic. Finally, we calculate and compare the potential energy curve of HBBODipic in solvent with different polarities. We present that the ESIPT process of HBBODipic could be regulated by solvent polarity; that is, nonpolar solvents are more favorable for ESIPT reaction for HBBODipic flurophore.