Structural diversity of Mn(ii), Zn(ii) and Pb(ii) coordination polymers constructed from isomeric pyridylbenzoate N-oxide ligands: structures and electrochemical properties

Abstract

Several new coordination polymers (CPs), [Mn(4,3-opybz)₂(H₂O)₂]_n (1), [Zn(4,3-opybz)(OH)]_n (2), {[Pb(4,3-opybz)(H₂O)]·(NO₃)}_n (3), {[Mn₃(4,4-opybz)₄(HCOO)₂(H₂O)₄]·6H₂O}_n (4), Zn(4,4-opybz)₂(H₂O)₂ (5) and {[Pb(4,4-opybz)(4,3-opybz)]·3DMF·7H₂O}_n (6) (4,4-Hopybz = 4-(4-pyridyl)benzoic acid N-oxide, 4,3-Hopybz = 4-(3-pyridyl)benzoic acid N-oxide), have been successfully synthesized and characterized by elemental analyses, IR spectroscopy, thermogravimetric analysis and single crystal X-ray diffraction. Structural analysis shows that complex 1 features a two-dimensional (2D) layer with a 6³ topology. Complexes 2 and 3 present a 2D layer architecture with a 4·8² topology. Complex 4 presents an unusual one-dimensional (1D) chain constructed with linear trinuclear secondary building units (SBUs). Complex 5 has a zero-dimensional (0D) structure which is further connected to form a 2D supramolecular network through O–H⋯O hydrogen bonding. Complex 6 exhibits a 2D layer which is further connected by π⋯π interactions to produce a three-dimensional (3D) supramolecular framework with 1D opening channels. Moreover, as an anode material, complex 6 exhibits a relatively high irreversible capacity of about 860 mA h g⁻¹ in the first discharge process and a reversible lithium storage capacity of up to 405 mA h g⁻¹ at 100 mA g⁻¹ after 100 cycles. The observation of good storage performance demonstrates that CPs are a prospective class of electrode materials for lithium ion batteries (LIBs).