Solvent induced conformational transformation of helical chains in new copper(II) coordination polymers

Abstract

Two isomeric copper-containing coordination polymers, which are constructed from chiral ligand thiazolidine 2,4-dicarboxylic acid (H 2 L), have been synthesized with the same formula of [CuL(DMF)] n ( 1 and 1′ ). Complex 1 was prepared through the reaction of H 2 L and Cu(ClO 4 ) 2 ·6H 2 O in the mixture of N,N-dimethylformamide (DMF) and methanol (V/V = 1:1). With the same reactants 1′ was obtained only using DMF as solvent. Single-crystal X-ray diffraction analysis exhibited that 1 is left-handed helical chain and crystallizes in chiral space group P 2 1 2 1 2 1 , while 1′ is right-handed helix with chiral and polar space group P 2 1 . In addition, both coordination polymers show obvious chiral and non-linear optical (NLO) properties, which were characterized by circular dichroism (CD) and second harmonic generation (SHG) measurements. Two novel copper-containing coordination polymers with chiral space group were synthesized by varying reaction solvents, which are isomeric one dimensional helical chain with different conformations (left-handedness and right-handedness). ► Two novel chiral copper(II) complexes were synthesized by varying reaction solvents. ► The two complexes are isomeric 1D left- and right-handed helical chain, respectively. ► Both complexes exhibit chiral and non-linear optical properties.