Sulfur-Bridged Co(II)-Thiacalix[4]arene Metal-Organic Framework as an Electrochemical Sensor for the Determination of Toxic Heavy Metals.

A novel sulfur-bridged metal-organic framework (MOF) [Co(TIC4R-I)0.25Cl2]·3CH3OH (Co-TIC4R-I) based on thiacalix[4]arene derivatives was successfully obtained using a solvothermal method. Remarkably, adjacent TIC4R-I ligands were linked via Co(II) cations to form a three-dimensional (3D) microporous architecture. Subsequently, Co-TIC4R-I was modified on a glassy carbon electrode (Co-TIC4R-I/GCE) to produce an electrochemical sensor for the detection of heavy-metal ions (HMIs), namely, Cd2+, Pb2+, Cu2+, and Hg2+, in aqueous solutions. It was found that Co-TIC4R-I/GCE exhibited wide linear detection ranges of 0.10-17.00, 0.05-16.00, 0.05-10.00, and 0.80-15.00 µM for Cd2+, Pb2+, Cu2+, and Hg2+, respectively, in addition to low limit of detection (LOD) values of 0.017, 0.008, 0.016, and 0.007 µM. Moreover, the fabricated sensor employed for the simultaneous detection of these metals has achieved LOD values of 0.0067, 0.0027, 0.0064, and 0.0037 µM for Cd2+, Pb2+, Cu2+, and Hg2+, respectively. The sensor also exhibited satisfactory selectivity, reproducibility, and stability. Furthermore, the relative standard deviation (RSD) values of Cd2+, Pb2+, Cu2+, and Hg2+ were 3.29, 3.73, 3.11, and 1.97%, respectively. Moreover, the fabricated sensor could sensitively detect HMIs in various environmental samples. The high performance of the sensor was attributed to its sulfur adsorption sites and abundant phenyl rings. Overall, the sensor described herein provides an efficient method for the determination of extremely low concentrations of HMIs in aqueous samples.

A three-dimensional manganese(II) coordination polymer with two functional properties: magnetism and photochemical detection.

Hydrothermal reaction of Mn2+ with the ditopic ligand 2,5-bis(1H-1,2,4-triazol-1-yl)benzoic acid (Hdtba) resulted in the complex poly[aqua[µ3-2,5-bis(1H-1,2,4-triazol-1-yl)benzoato-κ3N4:N4':O]chloridomanganese(II)] monohydrate], {[Mn(C11H7N6O2)Cl(H2O)]·H2O}n, (I). Coordination polymer I has been characterized by X-ray diffraction, IR spectroscopy, elemental analysis, thermogravimetry and susceptibility measurements. The topology of I corresponds to a three-dimensional (3,6)-conn net linked by {Mn2Cl2(COO)2} building blocks and dtba- anions. Significant antiferromagnetic exchange is observed within the dinuclear {Mn2Cl2(COO)2} subunits. A fit of the susceptibility data resulted in the magnetic parameters g = 1.93 and J = -1.52. Studies of the photoluminescence properties revealed that I represents a promising luminescence sensor for sensitively detecting dichromate ions in aqueous solution. The associated photochemical detection mechanism was studied in detail.

2,2',2'',2'''-(1,4-Phenyl-enedinitrilo)-tetra-acetic acid dihydrate.

In the title compound, C(14)H(16)N(2)O(8)·2H(2)O, the complete organic molecule is generated by crystallographic inversion symmetry. The dihedral angles between the aniline ring and the acetic acid groups are almost identical, viz. 82.61 (7) and 80.33 (7)°. In the crystal, O-H⋯O hydrogen bonds link the organic mol-ecules and water mol-ecules, forming zigzag chains the c axis. An intra-molecular O-H⋯O hydrogen bond is also observed.