Fluorescent Heteroacenes with Multiply-Bonded Phosphorus

An air-stable primary phosphine, 2,6-diphosphinonaphthalene-1,5-diol (4), has been synthesized and structurally characterized. A series of π-conjugated heteroacenes containing two phosphaalkene (PC) units, 2,7-R2-naphtho­[1,2-d:5,6-d′]­bi­(soxaphosphole)­s [R2-NBOP, R = tBu (5a), Ad (5b), and Ph (5c)], have been synthesized from reactions of 4 and benzimidoyl chlorides. These novel fluorescent analogues of organic acenes were characterized by multinuclear NMR, UV–vis, and fluorescence spectroscopy, cyclic voltammetry, and single-crystal X-ray diffraction experiments.