Recyclable Functionalized Material for Sensitive Detection and Exceptional Sorption of Hexavalent Chromium and Permanganate Ions with Biosensing Applications.

Environmental remediation with a single platform for selective sensing and removal of toxic analytes with recyclability of the material has always been a desirable system for sustainability. However, materials comprising all the abovementioned advantages are rarely known for oxoanions. We herein developed a fluorogenic napthalimide-based functionalized mesoporous silica material (SiO2@NBDBIA) as a signaling and remediation system for oxoanions (CrO42-, Cr2O72-, and MnO4-) from a pool of several anions. The fluorescence quenching of the SiO2@NBDBIA material in the presence of CrO42-, Cr2O72-, and MnO4- ions gives the limit of detection (LOD) values of 6.23, 25.2, and 20.32 ppb, respectively, which are well below the maximum contaminant level demarcated by the United States Environmental Protection Agency. The maximum adsorption capacities of the material for the abovementioned oxoanions are found to be 352, 363, and 330 mg/g, respectively, which are well above those mentioned in the literature reports. Contrary to the literature-dominated irreversible ion-exchange mechanism, the reversible hydrogen-bonded binding of the material with the oxoanions leads to the recyclability of the material easily, which is very rare in the literature. The DFT calculations were performed to examine the interactions between the material and oxoanions. For real applications, this material was also used as a fluorescence probe to detect these oxoanions in the actual water samples, and more interestingly, used as a biosensing probe for these oxoanions in the living organism Artemia salina through fluorescence imaging. Thus, the SiO2@NBDBIA material is a unique example of recyclable material for detecting and remediating oxoanions.

Synthesis, electronic structure, and structural characterization of the new, "non-innocent" 4,5-dithio-catecholate ligand, its metal complexes, and their oxidized 4,5-dithio-o-quinone derivatives.

The bifunctional ligand catechol-4,5 dithiol, H(2)Dtcat, has been synthesized, and the structure of the bis Br(-) adduct, (HS)(2)C(6)H(2)(OH)(2).2Ph(4)Br.H(2)O, has been determined. The syntheses, molecular structures, electronic structures, and magnetic properties of the monoanionic [(Dtcat(2-))(2)M](-), (M = Ni, V and M = Cu, VI) complexes have been obtained as Ph(4)PBr double salts, [M(S(2)C(6)H(2)(OH)(2))(2)][Ph(4)P](3)Br(2). These and the antiferromagnetically coupled dimeric [(Dtcat)(2)Fe][Ph(4)P](2).4DMF complex, VII, have been structurally characterized. The centrosymmetric [M(S(2)C(6)H(2)(OH)(2))(2)](-) complexes in the X-ray isomorphous V and VI are connected via H-bonding to Br(-) ions to form one-dimensional chains well separated from each other by the Ph(4)P(+) cations. Magnetic measurements show V to be a S = 1/2 and VI a S = O molecules. The distribution of electrons in these compounds have been determined by density functional theory calculations which show V to be a radical anion Ni(II) complex and VI a partially oxidized-ligand, reduced-copper complex. The 4,5 dithio-o-quinone [(Dtoq)(2)Ni][Ph(4)P](2) and [(Dtoq)(2)Cu][Ph(4)P](2) orthoquinone derivatives of V and VI have been obtained by oxidation, and their molecular structures have been determined. The dimeric {[FeS(2)C(6)H(2)(OH)(2)](2)}(2-) complex, (VII) also crystallizes in chains where all OH groups participate in extensive H-bonding. The structure of the dianion VII contains S-coordinated Fe(III) ions in a square pyramidal coordination. In VII, two low spin Fe(III) (S = 1/2) sites are weakly coupled antiferromagnetically with a mu(eff) of 2.81BM at 270 K and 0.91 BM at 10 K.