Preparation, Crystal Structure, and Properties of Five Metal‐Organic Complexes Based on a Triangular Nonplanar Carboxylate Ligand

A nonplanar triangular carboxylate ligand has been synthesized and applied to assemble metal-organic frameworks under hydro- or solvothermal conditions. Five new metal-organic complexes, [H 2 N(CH 3 ) 2 ] 2 [Cd(HTMBTC) 2 ]·2H 2 O-dmf (1), [Cu 3 (TMBTC) 2 (2,2'-bpy) 2 ]·H 2 O (2), [Zn 3 (TMBTC) 2 (H 2 O) 2 ]· H 2 O (3), [Cd 3 (TMBTC) 2 (H 2 O) 4 ]·4H 2 O (4), and [Cu 3 (TMBTC) 2 ] (5), (dmf = dimethylformamide; TMBTC = 2,4,6-trimethylbenzene-1,3,5-tricarboxylic acid; bpy = bipyridine) were crystallized; they possess four different structural types. In 1, the nonplanar carboxylate ligand connects the cadmium ion to give rise to a 2D (4,4) topological layer that contains two vertical left- and right-handed helical chains. In 2, the carboxylate ligands first link the copper ions to generate a 1D tubular unit, which can be considered the basic building block. The 1D tubular units are further connected by the ligand to form a 2D layer structure. Complexes 3 and 4 have similar structural types. The zinc and cadmium ions are connected by the ligand to form a bilayer framework that contains double (6,3) topological nets. Different from complexes 1-4, complex 5 has a 3D framework. The copper ions are first connected by the ligand to generate a bilayer structure that contains double (6,3) nets, which are further connected by sharing the copper ion to form the final 3D framework. Photoluminescence measurements of 1, 3, and 4 in the solid state at room temperature show that all three coordination networks exhibit similar, strong luminescence, which can be assigned to an intraligand π→π* transition.