A Fluorescent Blue Phosphazene Dye: Synthesis, Structure and Optical Properties of 1,6-Bis(Dimethylamino)-2,5,7,10-Tetraazo-1,6 lambda(5)-Diphosphapyrene

Herein we report on the synthesis, structure, and optical properties of the fluorescent blue phosphazene dye 1,6‐bis(dimethylamino)‐2,5,7,10‐tetraazo‐1,6λ5‐diphosphapyrene, which was isolated as the unexpected product of the reaction between 1,4,5,8‐(tetraamino)naphthalene and [P(NMe2)3Br]Br. This dye, which turned out to be soluble in water and a range of organic solvents (including hexane, tetrahydrofuran / petroleum ether, acetonitrile, and ethanol), was structurally characterized by XRD. Its absorption as well as emission spectra and their sensitivity to pH variations were analyzed. The experimental work is complemented by quantum chemical calculations on the possible intermediate on the way to the isolated product and on its pKa value.