A pair of 3D homochiral metal-organic frameworks: spontaneous resolution, single-crystal-to-single-crystal transformation and selective adsorption properties.

A novel achiral hexacarboxylic ligand L was synthesized. Spontaneous resolution occurred during the reaction of L with Eu(NO(3))(3) to produce a pair of enantiomers of 1a and 1b with a formula of [EuL(NO(3))(3)(H(2)O)]·13H(2)O, which possesses 1D chiral open channels formed by triple-stranded helical chains. When heated to 60 °C, 1a releases coordinated and partial lattice H(2)O molecules to give a complex of [EuL(NO(3))(3)]·4H(2)O (1a'), accompanied by a single-crystal-to-single-crystal transformation from 1a to 1a', with the space group changing from P2(1) to P3(1)2. The dehydrated 1 can selectively adsorb water over organic solvents and exhibits reversible water adsorption upon dehydration and hydration.