(2-Azoniaethyl)guanidinium dichloride - A promising phase-matchable NLO material employing a simple hydrogen bond acceptor in its structure
Abstract
(2-Azoniaethyl)guanidinium dichloride (AEGCl), a salt of a functional guanidine derivative, was prepared and characterised by single-crystal and powder X-ray diffraction analysis, elemental analysis and by NMR, UV-Vis and vibrational spectroscopy. The crystal structure of AEGCl, which crystallises with the symmetry of the chiral space group P21, is built up via simple and multicentred N-H...Cl hydrogen bonds and further supported by C-H...Cl contacts.
The compound is thermally robust and exhibits promising NLO properties with powder SHG efficiency better than potassium dihydrogen phosphate. In contrast, (2-azoniaethyl)guanidinium salts with inorganic oxoanions such as (2-azoniaethyl)guanidinium dinitrate and diperchlorate, synthesised for a comparison, form centrosymmetric crystal assemblies having several structurally independent ''molecules'' in their structures.