Magnetic properties and circular dichroism of 1D chains built from chiral mononuclear and non-chiral trinuclear Cu(II) complexes with α-aminocarboxylates

Coordination polymers Cu(l-Pro)(ClO4)(H2O)2 (1) and Cu3(Gly)4(H2O)2(NO3)2 (2) were synthesized and characterized structurally. Compound 1 possesses the structure of 1D chain, where Cu(II) ions are linked by carboxyl-group in syn-anti conformation in equatorial–equatorial mode. Compound 2 is polymeric chain, consisting from trinuclear blocks Cu3(Gly)4(H2O)22+. In each of these units Cu(II) ions are linked by carboxyl-group in the same way as in 1, while trinuclear units Cu3(Gly)4(H2O)22+ are linked by NO3− ions, acting as the bridges between Cu(II) ions of neighboring trinuclear units. Circular dichroism properties of 1 were studied in solid state and solution. Magnetic measurements revealed that there were ferromagnetic exchange interactions between Cu(II) ions in 1 (J = +1.22(1) cm–1 for Hamiltonian H ˆ = - 2 J ∑ i S i S i + 1 ) and 2 (J = +1.17(2) cm–1 for Hamiltonian H ˆ = - 2 J ( S ˆ 1 S ˆ 2 + S ˆ 2 S ˆ 3 ) + μ B gH ( S ˆ 1 + S ˆ 2 + S ˆ 3 ) ).