Self-assembly of a cobalt octacyanotungstate network into a giant chiral helix

Cyanide-bridged cobalt-tungstate one-dimensional networks, {[Co17W9(CN)72(LR or S)26(MeOH)4]·16MeOH·64H2O}n (1R or 1S : LR or S = N-(2-pyridylmethylene)-(R or S)-1-phenylethylamine), were synthesized. Single-crystal X-ray crystallography reveals that 1R has a cyanide-bridged chiral helical one-dimensional structure, in which cyanide-bridged {Co15W8} units are linked by Co–W–Co trinuclear units. The {Co15W8} unit consists of four trigonal bipyramidal {Co3W2} moieties. The helical chain structure has 31 screw symmetry and exists as a chiral one-dimensional network. The pitch of the helix is 38 Å, exceeding that of double-stranded B-DNA (∼34 Å). In the Co17W9 chain, fifteen of the Co(II) ions are paramagnetic, while the remaining two Co(III) ions and all nine W(IV) ions are diamagnetic. Overall, the chains show paramagnetic behavior in the range of 1.8–300 K.

Cyanide-bridged cobalt-tungstate one-dimensional networks, [Co17W9(LR or S)26(MeOH)4]·16MeOH·64H2O (1R or 1S : LR or S = N-(2-pyridylmethylene)-(R or S)-1-phenylethylamine), were synthesized. Single-crystal X-ray crystallography for 1R reveals it to have a chiral helical one-dimensional cyanide-bridged structure, in which cyanide-bridged [Co15W8] moieties are linked by Co–W–Co trinuclear units. The helical chain structure has 31 screw symmetry, and forms a one-dimensional chiral network. The pitch of the helix is 38 Å, exceeding that of double-stranded B-DNA (∼34 Å).Figure optionsDownload as PowerPoint slide