The structures of two aldazines: [1,1′‐(1E,1′E)‐hydrazine‐1,2‐diylidenebis(methan‐1‐yl‐1‐ylidene)dinaphthalen‐2‐ol] (Lumogen) and 2,2′‐(1E,1′E)‐hydrazine‐1,2‐diylidenebis(methan‐1‐yl‐1‐ylidene)diphenol (salicylaldazine) in the solid state and in solution

Abstract

A combination of NMR spectroscopy and theoretical methods Density functional theory including dispersion corrections (DFT‐D) was used to study the structures of Lumogen and salicylaldazine. In the solid state, Lumogen exists as the dihydroxy tautomer 1a (an azine, CN–NC) as was already known from an X‐ray determination. In a deuterated dimethyl sulfoxide solution, another tautomer is observed besides 1a; its structure corresponds to the hydroxy‐oxo tautomer 1b (a hydrazone, CN–NH–Csp2). In what concerns salicylaldazine, we have observed only the dihydroxy tautomer 2a. Copyright © 2013 John Wiley & Sons, Ltd.