A new multifunctional two-dimensional cobalt(II) metal-organic framework for electrochemical detection of hydrogen peroxide, luminescent sensing of metal ions, and photocatalysis

A new multifunctional cobalt(11)-based metal-organic framework, [Co(DCTP)(L)(H2O)(2)](n) (NCST-1, NCST = North China University of Science and Technology), was synthesized by self-assembly of Co (OAc)(2)center dot 4H(2)O with 1,4-bis(benzimidazol-1-ylmethyl)-benzene (L) and 2,5-dichloroterephthalic acid (H2DCTP). Single-crystal X-ray diffraction analyses reveal that NCST-1 is a 2D (4,4) sheet, which is further expanded into a 3D supramolecular network by O-H center dot center dot center dot O hydrogen bond interactions. A non-enzyme electro-catalytic sensor was developed for sensing hydrogen peroxide (H2O2) based on the NCST-1, which was cast-coated on glassy carbon electrode (GCE). The modified sensor exhibited a remarkable performance for H2O2 reduction with an extended liner range (5 mu M-7 mM, 7 mM-18 mM), a fast response time (3 s), a high sensitivity (52.55 mu A mM(-1) cm(-2)), and a low detection limit (6.86 mu M) in alkaline solution. Furthermore, NCST-1, as a luminescent probe, displayed prominent multifunctional sensing property for Fe3+, Hg2+ as well Ag+ through fluorescence quenching effect. The emission intensity of NCST-1 increases linearly with the increasing concentration of Fe3+ with a Stern-Volmer constant (K55) of 1.12 x 10(4) M-1 and a detection limit (LOD) of 0.13 mu M in aqueous solution. For mercury ion (II), K = 7.58 x 10(3) M-1 and LOD = 1.10 M. For silver ion (1), K-sv = 6.22 x 10(3) M-1 and LOD = 1.33 mu M. Finally, the photocatalytic activities of NCST-1 were evaluated in the degradation of methylene blue (MB), Rhodamine B (RhB), and methyl orange (MO). The degradation efficiency for MB reached up to 91.3%, although NCST-1 hardly showed degradation ability towards RhB and MO. (C) 2018 Elsevier Ltd. All rights reserved.