Structural and spectroscopic studies of 2,9-dimethyl-1,10-phenanthrolinium cation (DPH) with chloride, triflate and gold dicyanide anions. The role of H-bonding in Molecular recognition and enhancement of - stacking

The crystal structures of the pronated ligand, 2,9-dimethyl-1,10-phenanthrolinium (DPH) cation with selected counter anions (chloride (1), triflate (2), and gold dicyanide (3)) are reported. The role of a hydrogen bond interaction in influencing the solid state pi-pi stacking found in all three compounds has been investigated. In the chloride, and triflate adducts 1 and 2, respectively, the solid state morphology was stabilized by additional H-bonding interaction. In particular, compound 1 displays extensive network of H-bonding interaction where pi-pi stacked layers are interlinked through the H-bonding network. In compound 2, the H-bonding interaction is less pronounced and involves mainly the non-coordinating triflate anion and the protonated N atom of the cation connecting neighboring intra-layer molecules. In 3 a weaker interaction exists between the N atom of the Au(CN)(2)(-) anion and the protonated N of the ligand, but the system lacks extensive intra-or inter-layer H-bonding interaction that connects the neighboring molecules.