A stable Cd(II) coordination polymer with amino organic ligand as a rarely fluorescence red-shift and turn-on sensor toward methylmalonic acid

With the change of lifestyle, the health of society has become an increasingly serious problem. Methylmalonic acid (MMA) is a specific functional metabolic marker that is sensitive to vitamin B12 deficiency. Coordination polymers (CPs) are ideal candidates for fluorescence recognition analyte. A new Cd(II) CP with the formula of [Cd(bbip)(NH2-BDC)(H2O)]n(1, bbip = 2,6-bis(benzimidazol-1-yl)pyridine, NH2-H2BDC = 2-aminoterephthalic acid) was synthesized by mixed-ligand strategy and solvothermal method. The structure shows that the 1 belongs to one-dimensional double-stranded structure. The fluorescence results revealed that 1 could selectively detect MMA by fluorescence red shift and fluorescence enhancement (turn-on), and could be recognized by naked eyes. The detection limit of 1 toward MMA was 0.72 mu M. The sensing mechanism may be due to the electron transfer and the formation of exciplex. Moreover, this CP also displays good thermal stability, chemical stability and reusability. Importantly, 1 could be considered as the first example of fluorescence red-shift and turn-on CP sensor for MMA.