Four metal–organic frameworks based on a semirigid tripodal ligand and different secondary building units: structures and electrochemical performance

Abstract

Four new metal–organic frameworks (MOFs), [Co₃(TCPB)₂(CH₃OH)₄]·4DMF (1), [Cd₃(TCPB)₂(H₂O)₄]·3DMF·19H₂O (2), [Mn₃(TCPB)₂(H₂O)₂(DMF)₂]·2DMF (3), and [Zn₂(μ₃-OH) (TCPB)(H₂O)(DEF)]·3DEF (4) (H₃TCPB = 1,3,5-tri(4-carboxyphenoxy)benzene), have been successfully synthesized and structurally characterized. Structural analyses show that complexes 1–3 present two-dimensional (3,6)-connected kgd net topology with the Schläfli symbol of (4³)₂(4⁶·6⁶·8³) based on linear trinuclear M₃(COO)₆ (M = Co, Cd, and Mn) secondary building units (SBUs) and display distinct one-dimensional (1-D) channels. Complex 4 (Zn-TCPB) exhibits a rare three-dimensional twofold interpenetrated (3,6)-connected rutile topology with the Schläfli symbol of (4²·6¹⁰·8³) (4·6²)₂ based on the tetranuclear Zn₄(μ₃-OH)₂(COO)₆ clusters, which shows three different types of 1-D opening channels. In addition, as an anode material, the complex 4 (Zn-TCPB) electrode exhibits an irreversible high capacity in the first discharge process and a reversible lithium storage capacity of up to about 455 mA h g⁻¹ at 0.1 A g⁻¹ after 100 cycles. This might provide a new method for finding a promising candidate for the electrode materials in lithium-ion batteries.