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), {[Cd3(t-4-cpp)2(btadpe)2(H2O)2]·4(H2O)}n (2), [Cd(tpa)(tib)]n (3), [Cd2(t-3-cpp)2(bimb)]n (4), were succes-sfully constructed under the condition of solvothermal (H2casb ​= ​4-((carboxylatoethyl)sulfanyl)benzoic acid, H3(t-4-cpp) ​= ​2,4,6-tri(4-carboxylphenyl)pyridine, H2tpa ​= ​terephthalic acid, H3(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 {44·62}. 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 {42·65·83}{42·6}. 4 has a 2D two-fold interpenetrating architecture featuring a 2-nodal (3,4)-connected network with point symbol of {42·63·8}{42·6}. 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 ​× ​10−7 ​M, 2.80 ​× ​10−7 ​M and 3.25 ​× ​10−7 ​M based on 3σ/Ksv, respectively. Four Cd(II)-based MOFs have been successfully synthesized and characterized. The fluorescence quenching experiments results showed that 1–4 exhibits selective fluorescence sensing NB with the detection limits of 2–4 of 5.74 ​× ​10−7 ​M, 2.80 ​× ​10−7 ​M and 3.25 ​× ​10−7 ​M based on 3σ/Ksv, respectively. [Display omitted]