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 p-p 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 p-p 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. KEY WORDS : Phenanthroline, H-bonding, X-ray structure, p- p stacking Bull. Chem. Soc. Ethiop. 2016 , 30(2), 231-239. DOI: http://dx.doi.org/10.4314/bcse.v30i2.7