Charge?{transfer Complexation and Photostability Characteristics of Iodine with bis-1,8-naphthalimide as a Photosensitive Biologically Active Units in Solution and in the Solid State: Linear Correlation of Photostability and Dissociation Energy

摘要

A combined solution and solid state study was performed to describe the complexation chemistry ofiodine with three highly fluorescent bis-1,8-naphthalimide dyes. The spectroscopic properties,photostability characteristics and the mechanism of interaction were investigated and discussed. Theformed complexes were characterized stoichiometrically and structurally using ultraviolet-visible, mid-and far-infrared spectral techniques, as well as CHN elemental analyses. A remarkable change in theUV-Vis spectra was observed when the iodine acceptor was complexed with a 1:2 stoichiometry. Far- - IR measurements confirmed the formation of triiodide (I3 ). The formation constant, molar extinctioncoefficient and other spectroscopic data were also determined and discussed. It has been found that thecomplexation with iodine increases the photostability of the reported dyes. Interestingly, a strong linearcorrelation (r = 0.991) between half-life of photostability and dissociation energy in solution is clearlyevidenced for the first time.