Self-assembly of 3-D 4d–4f coordination frameworks based on 1-D inorganic heterometallic chains and linear organic linkers

Four novel 4d–4f heterometallic coordination polymers, namely, LnAg(pydc)2(Hnic)0.5 [Ln = Nd (1), Eu (2); H2pydc = pyridine-3,4-dicarboxylic acid, Hnic = nicotinic acid], and LnAg(inic)2(nicO)·0.5H2O [Ln = Nd (3), Eu (4); Hinic = isonicotinic acid, H2nicO = 2-hydroxynicotinic acid], have been synthesized and characterized. Compounds 1 and 2 exhibit three-dimensional (3-D) coordination frameworks constructed by one-dimensional (1-D) inorganic heterometallic chains and linear pydc linkers. The 1-D channels occupied by disordered Hnic molecules emerge. To our knowledge, both compounds represent the first examples of 3-D open-framework 4d–4f heterometallic coordination frameworks. Compounds 3 and 4 display 3-D covalent frameworks composed of 1-D inorganic heterometallic chains joined by inic ligands, representing the first examples of 3-D 4d–4f coordination frameworks constructed by inorganic heterometallic chain and mixed linear and nonlinear ligands with same donors. Furthermore, the luminescent properties of 2 and 4 were studied.