Role of peripheral phenanthroline groups in the self-assembly of self-assembled molecular triangles

Abstract

Self-assembled molecular triangles [Pd3(phen)3(imidazolate)3](NO3)3, 1a and [Pd3(phen)3 (imidazolate)3](PF6)3, 1b are prepared by the combination of imidazole with Pd(phen)(NO3)2 and Pd(phen) (PF6)2, respectively. Imidazole was deprotonated during the complexation reactions and the imidazolate so formed acted as a bis-monodentate bridging ligand to form the bowl-shaped trinuclear architectures of 1a/b. Relative orientation of the imidazolate moieties can be best described as syn,anti,antias observed in the crystal structure of 1b. However, in solution state, slow conformational changes are assumed on the basis of 1HNMR spectral data. The molecular triangles are crafted with three peripheral phen units capable of π−π stacking interactions. Well-fashioned intermolecular π−π interactions are observed in the solid-state, wherein further self-assembly of already self-assembled triangle is observed. Self-assembly of the self-assembled molecular triangle [Pd3(phen)3(imidazolate)3](PF6)3 is observed in the solid-state where the triangular panels are packed by utilizing intermolecular π−π interactions in a chain like fashion.