Four Cd(II)-based metal organic frameworks: Syntheses, structures and fluorescent probes for highly selective, sensitive detection for nitrobenzene

Four Cd-MOFs named [Cd(casb)(bimb)](n) (1), {[Cd-3(t-4-cpp)(2)(btadpe)(2)(H2O)(2)].4(H2O)}n (2), [Cd(tpa)(tib)](n )(3), [Cd-2(t-3-cpp)(2)(bimb)]n (4), were succes-sfully constructed under the condition of solvothermal (H(2)casb = 4((carboxylatoethyl)sulfanyl)benzoic acid, H-3(t-4-cpp) = 2,4,6-tri(4-carboxylphenyl)pyridine, H(2)tpa = terephthalic acid, H-3(t-3-cpp) = 2,4,6-tri(4-carboxylphenyl)pyridine, bimb = 1,4-bis(imidazole-1-ylmethyl)benzene, btadpe = 4,4'-bis(4H-1,2,4-triazol-4-yl)diphenyl ether, tib = 1,3,5-tirs(1-imidazolyl)benzene). Four complexes were characterized by X-ray single-crystal diffraction, elemental analysis, IR spectra. 1 exhibits a two-dimensional (2D) framework with three-fold interpenetrating architecture featuring an uninodal 4-connected network with point symbol of {4(4).6(2)}. 2 features a three-dimensional (3D) network sructure. 3 shows a 3D two-fold interpenetrating architecture framework featuring a 2-nodal (3,5)-connected network with point symbol of {4(2).6(5).8(3)} {4(2).6}. 4 has a 2D two-fold interpenetrating architecture featuring a 2-nodal (3,4)-connected network with point symbol of {4(2).6(3).8}{4(2).6}. Furthermore, the fluorescence quenching experimental results showed that 1-4 exhibits selective fluorescence sensing nitrobenzene (NB). The concentration-fluorescence experimental result shows that the detection limit of 2-4 for NB is 5.74 x 10(-7) M, 2.80 x 10(-7) M and 3.25 x 10(-7 )M based on 3 sigma/K-sv, respectively.