Self-assembly of N,N′,N″-tris(4-pyridyl)trimesic amide and N,N′,N″-tris(3-pyridyl)trimesic amide with AgIor CdIIions

Abstract

We report herein an interesting family of tripyridyltriamides (L1 ≡ N,N′,N″-tris(3-pyridyl)trimesic amide, L2 ≡ N,N′,N″-tris(4-pyridyl)trimesic amide) used as tridentate bridging ligands to carry out crystal-engineering studies. The reaction of AgPF6 with L1 leads to a 2-D coordination polymer, [Ag(L1)PF6]n (1). The 48-membered macrocycles constructed from three-coordinate AgI ions as connectors and three tripyridyltriamide moieties propagate into 2-D extended structures. Indeed, the AgI⋯π interaction (the distance of the AgI⋯centroid of benzene is 3.209 A) increases the supramolecular complexity, and leads to inter-sheet dimerization. The reaction of CdCl2 with L2 forms a 3-D coordination network, [Cd(L2)2Cl2]n (2). The open channels with a diameter of ca. 7.5 A containing the tripyridyltriamide moieties propagate into 3-D extended structures. This is an interesting example of 3-D coordination networks containing tripyridyltriamides as functional moieties inside the channels. However, the channels are filled with disordered water molecules and chloride anions, where the latter are appended through hydrogen-bonding interactions with the amide moieties inside the channels. In addition, 1 displays a high-energy emission with a maximum at ca. 450 nm, whereas 2 shows a low-energy emission with a maximum at ca. 532 nm. The former with a ca. 450 nm emission is assigned to an intraligand transition, and the latter with a ca. 532 nm emission is tentatively ascribed to a metal-to-ligand charge-transfer transition.