Novel Inorganic–Organic Hybrid Frameworks of Manganese(II): Syntheses, Crystal Structures, and Physical Properties

Abstract

Three new inorganic–organic hybrid frameworks, [Mn₂(BPTCA)(phen)₂·H₂O]_<i>n</i> (<b>1</b>), [Mn₄(BPTCA)₂(H₂O)₁₀·2.5H₂O]_<i>n</i> (<b>2</b>), and [Mn₂(BPTCA)(μ₂-H₂O)₂]_<i>n</i> (<b>3</b>) (BPTCA⁴⁻ = 4,4′-bipyridine-2,2′,6,6′-tetracarboxylate; phen = 1,10-phenanthroline), have been synthesized under hydrothermal conditions. Complex <b>1</b> is a two-dimensional (2D) network constructed by infinite O−Mn−O−C−O−Mn- chains and BPTCA⁴⁻ ligands, and an intriguing slide fastener-like three-dimensional (3D) framework structure is formed by the π···π interactions between the phen molecules. Complex <b>2</b> crystallized in a chiral space group <i>P</i>2₁ has a 2D network structure formed by Mn₄ cluster units and BPTCA⁴⁻ linkers, while complex <b>3</b> obtained at higher temperature than <b>2</b> is a 3D porous architecture. The result implies that the hydrothermal reaction temperature has a great influence on the structure of the complexes in this system. The magnetic behaviors of the complexes have been investigated and <b>2</b> showed modest powder second harmonic generation activity.