Racemic twin crystals containing left- and right-handed polyoxometalate chains induced by the asymmetric coordination of metal–organic units

Two racemic twin crystals containing left- and right-handed polyoxometalates (POMs) chains [Cu(en)2][Cu(en)2(H2O)]2 [SiW11CuO39] · 5H2O (D-1 and L-1; en = ethylenediamine) have been synthesized and structurally characterized. Both chiral compounds (D-1 and L-1) were constructed from the achiral building blocks [SiW11CuO39]6− and [Cu(en)2(H2O)n]2+ (n = 0 or 1). The structural chirality is induced by the [Cu(en)2(H2O)n]2+ units asymmetrically coordinated on the chainlike [SiW11CuO39]n6n− polyoxoanions, leading to the whole molecules crystallized in the chiral P1 space group. The chiroptical activities of D-1 and L-1 were confirmed by the solid-state circular dichroism spectroscopy. Their electrochemical and electrocatalytic properties were also investigated.