Scheme 1. General Chemical Structure of ICT Molecules, Schematic of Electronic Transitions and Fluorescence Spectra.

(a) Chemical structure of ICT molecules, the DMABN, and others by mentioning the donor, chromophore, and acceptor groups. (b) The electronic energy-level diagram for the dual emission LE and ICT in a polar solvent. (c) Sketch of fluorescence spectra of an ICT molecule in polar and nonpolar solvents to show the dual emission.