Study of four new Cd(II) metal-organic frameworks: syntheses, structures, and highly selective sensing for 4-nitrophenol

Abstract Four new mixed ligand based metal-organic frameworks (MOFs), devised as [Cd(AA)(bpa)(OH2)]n (MOF-AA), [Cd(PA)(bpa)]n (MOF-PA), {[Cd(SUA)(bpa)].CH3OH}n (MOF-SUA) and {[Cd(AzA)(bpa)].2CH3OH}n (MOF-AzA) (where, AA = adipic acid; PA = pimelic acid; SUA = suberic acid; AzA = azelaic acid; bpa = 1,2-bis(4-pyridyl)ethane) have been synthesized, and successfully identified by elemental analyses, FT-IR, powder X–ray diffraction, single-crystal X–ray diffraction, and thermal analyses. MOF-AA exhibits 3D coordination network with new honey comb topology (4-c, uninodal net), while MOF-PA shows 2D structure with hxl/Shubnikov plane net topology (6-c, uninodal net). MOF-SUA and MOF-AzA display 2D frameworks with sql/Shubnikov tetragonal plane net topology (4-c, uninodal net). The luminescence studies affirm that the emissions from MOFs owing to π-electron rich ligand establish charge transfer transitions (n–π* and π–π*). MOF-AA has attractive luminescent property, and exhibits distinguished applications for the selective as well as sensitive detection of 4-nitrophenol.