A novel layered Cu-based perovskite metal–organic framework with 1,2-diaminoethane cations: synthesis, crystal structure, and thermal and magnetic properties

Abstract

Lead-free organic–inorganic metal perovskites have recently attracted special attention. Here, we report on the synthesis of single crystals of a new layered perovskite-type formate framework templated by diprotonated ethylene diammonium (NH₃(CH₂)₂NH₃)[Cu(HCO₂)₄]∞ (1) using a mild solution chemistry approach. The as-prepared sample was characterized by single crystal X-ray diffraction (SCXRD), Fourier transform infrared spectrophotometry, thermogravimetric analyses, and differential scanning calorimetry. We also studied its magnetic properties. SCXRD data show that 1 crystallizes as a monoclinic structure in the P2₁/c space group, and its structure consists of [Cu(HCO₂)₄]²⁻ anionic squared layers and an (NH₃(CH₂)₂NH₃)²⁺ cation interlayer. In the layers, divalent copper cations Cu²⁺ have an octahedral geometry and are bridged by the equatorial formate HCO₂⁻ in an infinite anti–anti chain. The (NH₃(CH₂)₂NH₃)²⁺ cation interlayer forms N–H⋯O_formate extensive H-bonds to anionic layers. IR absorption bands are characteristic of the ethylene diammonium cation and formate group and are consistent with X-ray diffraction data. TGA results reveal that the studied compound starts to decompose at 373 K. The magnetic study reveals a two-dimensional Heisenberg antiferromagnetic behaviour with moderate interactions between Cu(II) ions through O–C–O bridges. A weak ferromagnetism has also been detected arising from spin canting in an ordered antiferromagnetic material.