Effects of strong hydrogen bonds and weak intermolecular interactions on supramolecular assemblies of 4-fluorobenzylamine

Abstract

A series of supramolecular salts have been obtained by the self-assembly of 4-fluorobenzylamine and halide ions or metal chloride with 18-crown-6 as the host in the hydrochloric acid medium, i.e. (C7H9FN)+⋅X− (X=Cl−, 1; Br−, 2), [(C7H9FN)2⋅(18-crown-6)2]2+⋅(MCl4)2− (M=Mn, 3; Co, 5; Zn, 7; Cd, 8), [(C7H9FN)⋅(18-crown-6)]+⋅(FeCl4)− (4) and [(C7H9FN)⋅(18-crown-6)]+⋅1/2(CuCl4)2− (6). Structural analyses indicate that 1–2 crystallize in the triclinic space group P−1, 4 in orthorhombic space group Pnma and 3, 5, 6–8 in the monoclinic space group P21/c or C2/c. In these compounds, extensive intermolecular interactions have been utilized for the self-assembly of diverse supramolecular architectures, ranging from strong N–H⋯X (X=O, Cl, Br) hydrogen bonds to weak C–H⋯Y (Y=F, Cl, π) interactions. N–H⋯Cl/Br hydrogen bonds offer the major driving force in the crystal packing of salts 1–2 while N–H⋯O hydrogen bonds are found in salts 3–8.