Three open frameworks,[Ni (pnta) 2]· 1.3 DMF (1),[Zn2 (pnta) 3 (OH)]· 2DMF (2), and [Cd (pnta) 2]· 3.8 DMF (3), were obtained by solvothermal reactions between 6-(pyridin-4-yl) nicotinic acid (Hpnta) and nickel (II), zinc (II) and cadmium (II) nitrate, respectively. Compound 1 is a chiral framework with a fourfold interpenetrated diamondoid network structure and two types of chiral channels. Compound 2 also possesses the fourfold ...