Homochiral 1D Helical Chain Based on an Achiral Cu(II) Complex

Abstract

Self-assembly of an achiral [Cu­(L)] complex produced a homochiral helical chain [Cu­(L)]₃·2H₂O (<b>1</b>) (L = 2-dimethylaminoethyl­(oxamato)). Interestingly, complex <b>1</b> obtained in our laboratory exhibits only a left-handed helical chain without any chiral source. Single-crystal X-ray analysis revealed the absolute structure and homochirality of its helical chain structure in the space group of <i>P</i>3₂. Solid-state circular dichroism (CD) spectra confirmed the high enantio excess of the crystals obtained in different synthesis batches. Magnetic susceptibility measurements reveal a relatively strong intrachain antiferromagnetic interaction between Cu­(II) centers via an oxamato bridge (<i>J</i> = −74.4 cm^–1)