Solvothermal Synthesis, Structure, and Properties of Metal Organic Framework Isomers Derived from a Partially Fluorinated Link Published as part of a virtual special issue on Structural Chemistry in India: Emerging Themes

Solvothermal reactions of Cu(NO3)23 3H2O with 4,4 0 -(hexafluoroisopropylidene) bis(benzoic acid) (C17H10F6O4 ,H 2hfbba) and terminal monodentate ligand 3-methyl pyridine (3-picoline/3-mepy) in the presence of N, N-dimethyl formamide (DMF) and N,N-diethyl formamide (DEF) solvents gave rise to two structurally different two- dimensional (2D) fluorinated metal organic frameworks (F- MOFs). The effect of the choice of solvent has been clearly reflected in the structures obtained. The F-MOFs reported in this paper are formulated as (Cu2(hfbba)2(3-mepy)2) 3 (DMF)2(3- mepy) (F-MOF-4), (Cu2(hfbba)2(3-mepy)2)(Cu-F-MOF-4B), and (Zn2(hfbba)2(3-mepy)2) 3 (3-mepy) (Zn-F-MOF-4B) which displays interesting 2D structures with and without interdigitation depending on the solvent used. The structures of these F-MOFs have been determined by X-ray crystallography and further identified by IR spectroscopy, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). The effect of interdigitation has been reflected in the gas adsorption and magnetic properties of these F-MOFs. These F-MOFs also show comparable H2 and CO2 uptake depending on their structural variation. Temperature- dependent magnetic susceptibility measurements over a wide range of temperatures exhibit dominantly short-range antiferromag- netic behavior, with weak ferromagnetic behavior showing up at very low temperatures, which is evident from opening of the hysteresisloopwitha finitevalueofcoercivityinbothF-MOF-4andCu-F-MOF-4B.Weobservedasmallervalueof μeffperCuatom andcoercivityinCu-F-MOF-4BthantheF-MOF-4duetorelativelylargerdistancesbetweentheneighboringdicopperpaddlewheel secondary building unit.