Homochiral Metal−Organic Frameworks Based on Transition Metal Bisphosphonates

Abstract

Homochiral metal−organic frameworks with binaphthylbisphosphonate bridging ligands [Mn(L-H2)(MeOH)]·(MeOH), 1, [Co2(L-H2)2(H2O)3]·(H2O)4, 2, [Ni(L-H2)(MeOH)4], 3, [Cu(L-Et2)], 4, and [Zn3(L-H)2(C6H5N)2], 5, where L is completely deprotonated enantiopure 2,2‘-diethoxy-1,1‘-binaphthalene-6,6‘-bisphosphonic acid, were synthesized under hydro(solvo)thermal reactions. Single-crystal X-ray diffraction studies reveal that 3−5 adopt condensed network structures, while compounds 1 and 2 adopt robust three-dimensional open-framework structures possessing rhombohedral channels. Solid-state circular dichroism spectra indicate that compounds 1−5 made from bridging ligands of opposite handness are supramolecular enantiomers. Compounds 1, 5, and L-H4 exhibit strong blue fluorescence in solid state, and the formation of excimers in 5 and L-H4 in solid state correlates well with the π−π stacking interactions. The present work illustrates the potential of rational synthesis of robust chiral porous network solids. The chira...