Preparation, structure and luminescent characterization of a series of metal-organic frameworks based on flexible ligands with nitrogen heterocycles and carboxyl

Seven new compounds, [ZnPyPymba2]n(1), [Co(PyPymba)2]n(2), [Cd(PyPymba)2]n(3), [Cd(HPyPymba)Cl2]n(4), {[Cd(PyPymba)Cl]·C2H5OH·H2O}n(5), [Cd(PyPyaa)Cl]n(6),{[Cd2(PyznPy)2Cl2H2O]·H2O}n(7) [Hpypymba = 4-((3-(pyrazin-2-yl)-1H-pyrazol-1-yl)methyl)benzoic acid,HPyznPy = 4-((3-(pyridin-2-yl)-1H-pyrazol-1-yl)methyl)benzoic acid, HPyPyaa = 2-(3-pyridin-2-yl)-1H-pyrazol-1-yl)acetic acid], were hydrothermally synthesized by tuning the metal ion's species, counter anion, solvents and pH values and characterized by routine method using XRD, elemental analysis , fluorescence properties analysis, TGA and crystal structure analysis and single-crystal X-ray crystallography. The coordination mode of the counter anion and the change of the coordination point are the main reasons that affect the rich and diversity of compound's structure. The fluorescence quenching of compound 7 shows that 7 can detect microscale amounts of nitrobenzene(10−3 mol/L) and trace amounts of Fe3+ (9 × 10−7 mol/L).215