Tuning of magnetic frustration in S=1/2S=1/2 Kagomé lattices {[Cu3(CO3)2(bpe)3](CLO4)2}n and {[Cu3(CO3)2(bpy)3](CLO4)2}n through rigid and flexible ligands

•Frustrated S=1/2 Kagome lattices Cu-bpe and Cu-bpy are synthesized.•Structural and magnetic properties are investigated.•Both the compounds are moderately frustrated and undergo ferromagnetic ordering at low temperatures.•Replacement of bpe by bpy ligand leads to an reduction in frustration parameter.

Single crystalline and polycrystalline samples of S=1/2S=1/2 Kagomé lattices {[Cu3(CO3)2(bpe)3](CLO4)2}n{[Cu3(CO3)2(bpe)3](CLO4)2}n and {[Cu3(CO3)2(bpy)3](CLO4)2}n{[Cu3(CO3)2(bpy)3](CLO4)2}n, respectively were synthesized. Their structural and magnetic properties were characterized by means of x-ray diffraction and magnetization measurements. Both compounds crystalize in a hexagonal structure (space group P−6) consisting of CuO4 Kagomé layers in the ab-plane but linked along c direction through either rigid bpy or flexible bpe   ligands to form 3D frame works. Magnetic measurements reveal that both the compounds undergo ferromagnetic ordering (TCTC) at low temperatures and the TCTC and the extent of frustration could be tuned by changing the nature of the pillar ligands. {[Cu3(CO3)2(bpe)3](CLO4)2}n which is made up of flexible bpe   ligands has a TCTC of 5.7 K and a Curie-Weiss temperature (θCWθCW) of −39.7 K giving rise to a frustration parameter of |θCW|/TC≃6.96|θCW|/TC≃6.96. But the replacement of bpe by a more rigid and electronically delocalized bpy   ligand leads to an enhanced TC≃9.3K and a reduced frustration parameter of |θCW|/TC≃3.54|θCW|/TC≃3.54.