Chirality- and threefold-symmetry-directed assembly of homochiral octupolar metal-organoboron frameworks.
Homochiral octupolar metal-organoboron frameworks with the general formula [M(2)L(OH)(MeOH)] x 3 H(2)O [M = Co (1), Mn (2), Ni (3), Cu (4), Zn (5), Cd (6)] have been constructed from racemic C(3)-symmetric tris(4-benzoic acid)tridurylborane and the divalent metal ions. Compounds 1-6 are isostructural and crystallize in the chiral cubic space group F432, and they adopt an eightfold-interpenetrating (10,3)-a network formed by linking bimetal building blocks with three bidentate carboxylate groups of bridging Lambda-L ligands. Bulk crystals of each of the six compounds are not a racemic mixture, and their optical activity and enantiomeric nature were demonstrated by solid-state circular dichroism spectra. Consistent with their polar structures, the colorless compounds 5 and 6 exhibit powder second harmonic generation intensities 3-4 times higher than that of potassium dihydrogen phosphate, making them, to the best of our knowledge, the first two examples of NLO-active, homochiral octupolar metal-organic solids.
School of Chemistry and Chemical Technology and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China.
Yan
Y
Liu
Weimin
W
Xuan
Hui
H
Zhang
Yong
Y
Cui