A 3D chiral supramolecular framework of Cu(II): Synthesis, structure and magneto-structural correlations

A metal-organic coordination chain of Cu(II), viz {Cu(Hbtc)(NH₃)₄](H₂O)}_n (1) (btc = benzenetricarboxylate) has been synthesized and structurally characterized. The sky blue single crystals of 1 were grown by the dissolution of the as-synthesized insoluble product obtained from the reaction of Cu(II), H₃btc and 4,4′-bipy in aqueous NH₃ solution. Structural determination reveals that 1 crystallizes chiral P2₁2₁2₁ space group and 1D coordination chain of Cu(II) bridged by the Hbtc linker. 1D chains are H-bonded via the guest water molecules forming a 2D sheet like structure and 2D sheets through π-π and N-H···O H-bonding interactions produce a 3D supramolecular framework with 1D water filled channels along the a-axis. Temperature dependent magnetic measurement exhibits weak antiferromagnetic intrachain interaction between Cu(II) centers through the Hbtc linker with J = −0.17 cm⁻¹ and g = 2.01 and at low temperature interchain ferromagnetic interaction is predominates. The dominant antiferromagnetic interaction is supported by the DFT calculations.