Coordination polymers based on mu sup(2)Eta sup(1):Eta sup(1) and mu sup(2)Eta sup(2):Eta sup(2) bridging mode of pyridyl carboxylate: ionic liquid-induced hydrothermal synthesis, structural and thermogravimetric analysis

Abstract

Two coordination polymers of formula [Cu(2-picolinate)(nicotinate)] sub(n) (1), [Mn(2-picolinate) sub(2)] sub(n) (2), using pyridine-2/3-carboxylic acid and metal salt acetate, have been synthesized hydrothermally at 120 degrees C for 48 h in presence of ionic liquid tetraethylammonium hydroxide (25% aqueous solution). Although all reported complexes were synthesized in same experimental conditions, they show diversity in their structural features, 2 crystallize in monoclinic crystal system where as 1 shows higher symmetry space group, orthorhombic. The 3D structure in 1 is based on anti-syn Cu–O–C–O–Cu chain with mu sup(2)Eta sup(1):Eta sup(1) coordinative mode of carboxylate ion and ligand bridging through carboxylate oxygen and pyridyl nitrogen of nicotinate ion while 2D sheet structure in 2 is due to Mn–O–Mn chain involving mu sup(2)Eta sup(2):Eta sup(2) coordinative mode together with syn-anti Mn–O–C–O–Mn chain via mu sup(2)Eta sup(1):Eta sup(1) coordinative mode of carboxylate ion of picolinate ion only. It is observed that these chains are the structure factors for dimensionality of reported CPs. Both coordination polymers are insoluble in almost all organic solvents as well as in water and show good thermal stability between 280 and 450 degrees C.