Solvent influence on the photophysical properties of 4-methoxy-N-methyl-1,8-naphthalimide

4-Methoxy-N-methyl-1,8-naphthalimide (1) exhibits considerable solvatochromism and its UV–vis spectral properties have been studied in several polar/non-polar and protic/aprotic solvents, as well as in ethanol–water mixtures. The results reveal a strong influence of the solvent's polarity and its hydrogen-bond donor (HBD) capability on the photophysical properties of 1. For binary ethnaol/water mixtures, preferential solvation models describe the band shifts in the probe's visible absorption spectrum well, but they fail to describe the correponding shifts of the emission maxima. Pseudolinear approximations between solvent composition and molecule's transition energies, ET, can be used to study the composition of ethanol–water mixtures, simplifying the mathematical treatment for eventual analytical applications.