The increase of the global population and shortage of renewable water resources urges the development of possible remedies to improve the quality and reusability of waste and contaminated water supplies. Different water pollutants, such as heavy metals, dyes, pesticides, endocrine disrupting compounds (EDCs), and pharmaceuticals, are produced through continuous technical and industrial developments that are emerging with the increasing population. Molecularly imprinted polymers (MIPs) represent a class of synthetic receptors that can be produced from different types of polymerization reactions between a target template and functional monomer(s), having functional groups specifically interacting with the template; such interactions can be tailored according to the purpose of designing the polymer and based on the nature of the target compounds. The removal of the template using suitable knocking out agents renders a recognition cavity that can specifically rebind to the target template which is the main mechanism of the applicability of MIPs in electrochemical sensors and as solid phase extraction sorbents. MIPs have unique properties in terms of stability, selectivity, and resistance to acids and bases besides being of low cost and simple to prepare; thus, they are excellent materials to be used for water analysis. The current review represents the different applications of MIPs in the past five years for the detection of different classes of water and wastewater contaminants and possible approaches for future applications. 相似文献
The design, synthesis, and characterization of the 10 linear and bent acentric ligands 1 – 10 (tectons) based on the differentiation of two divergently disposed coordinating poles is reported. The nature of the two poles and their distance are varied by the use of different linear spacers. For these molecules, a monodentate coordinating site, i.e., a pyridine ring, and a tridentate coordinating site, i.e., a pyridine moiety bearing at the 2 and 6 positions either two thioether groups or two dimethylamino units (PySMe and PyN(Me2)2 type, resp.), a terpyridine, or a pyridine ring bearing two optically pure dihydrooxazole units, are combined. 相似文献
Important aspects of the electrochemical reduction of a series of substituted benzyl thiocyanates were investigated. A striking change in the reductive cleavage mechanism as a function of the substituent on the aryl ring of the benzyl thiocyanate was observed, and more importantly, a regioselective bond cleavage was encountered. A reductive alpha-cleavage (CH(2)-S bond) was seen for cyano and nitro-substituted benzyl thiocyanates leading to the formation of the corresponding nitro-substituted dibenzyls. With other substituents (CH(3)O, CH(3), H, Cl, and F), both the alpha (CH(2)-S) and the beta (S-CN) bonds could be cleaved as a result of an electrochemical reduction leading to the formation of the corresponding substituted monosulfides, disulfides, and toluenes. These final products are generated through either a protonation or a nucleophilic reaction of the two-electron reduction-produced anion on the parent molecule. The dissociative electron transfer theory and its extension to the formation/dissociation of radical anions, as well as its extension to the case of strong in-cage interactions between the produced fragments ("sticky" dissociative electron transfer (ET)), along with the theoretical calculation results helped rationalize (i) the observed change in the ET mechanism, (ii) the dissociation of the radical anion intermediates formed during the electrochemical reduction of the nitro-substituted benzyl thiocyanates, and more importantly (iii) the regioselective reductive bond cleavage. 相似文献
Dithiobisphthalimide is used as a new precursor for the spontaneous deposition of sulfur on gold surfaces in acetonitrile. Characterization of the modified surfaces is achieved using X‐ray photoelectron spectroscopy (XPS), electrochemistry and scanning tunneling microscopy (STM). The reported results indicate that the sulfur deposition is an efficient and fast process and that high coverages can be reached very quickly. Sequential high‐resolution STM in air allows the direct observation, for the first time, of the mobility of the usually observed rectangular structures as individual units. It also shows the reversible association/dissociation of these rectangles. The nature of these structures is highly debated in the literature and the present work provides new insights into their nature through the use of a new sulfur precursor under non‐traditional conditions. To explain our results we consider these structures as simple sulfur adlayers on the gold surface. 相似文献
The salt bis benzyl ammonium monohydrogentetraoxoarsenate(V) monohydrate [C6H5CH2NH3+]2HAsO42−·H2O, M = 373.92, Triclinic, P−1. a = 6.514(1), b = 8.910(2), c = 15.061(3) ?, α = 99.26(2), β = 93.93(1), γ = 97.64(1)°, V = 851.5(3), Z = 2, Dx = 1.460, λ (MoKα) = 0.71073 ?, μ = 0.99 mm−1, F(000) = 126, T = 20(2) °C, final R = 0.673 for 5488 unique reflections. Planes of HAsO42− alternate with planes of C6H5CH2NH3+ groups. The structure consists of infinite parallel two-dimensional planes built of mutually connected ions and water molecules
by strong O–H···O and N–H···O hydrogen bonding. There are no contacts other than van der Waals interactions between the layers.
Differential scanning calorimetry study on bis benzyl ammonium monohydrogentetraoxoarsenate(V) monohydrate was carried out.
The infrared of polycrystalline samples of this compound have been recorded at room temperature. 相似文献
This work deals with the concept of satisfactory solution for Stochastic Multiobjective Programming (SMP) problems. Based on previous literature, we will introduce different concepts of satisfactory solutions for SMP problems, define a new concept of solution (where the decision maker (DM) sets his/her preferences in terms of two aspiration levels for the stochastic objective and two probabilities to reach those levels), and establish some relationship between these concepts. The results will aim at featuring these concepts and determine the differences between them. Moreover, the paper proposes a new step by step procedure to exchange information between the analyst and DM prior to solving the problem. Thus, the DM will be able to choose the transformation criterion for each stochastic objective and the aspiration level. 相似文献
An isomeric series of dehydro[m]pyrido[n]annulenes incorporating strained 1,4-buta-1,3-diyne units have been synthesized, where m = 2, n = 14 (1a-d); m = 2, n = 15 (2a,b); and m = 3, n = 15 (3). The number of pyridine rings and annulene ring π-electrons are denoted by m and n, respectively. The X-ray crystal structures of 1b and 1c confirmed their cyclic formulation. All macrocycles were found to be luminescent chromophores with differing isomer-dependent proton and metal ion-sensory emission responses, which appear collectively as analyte-specific color patterns. Within the series studied, 1a was singular in displaying the highest luminescence quantum yield and sharing the strongest emission energy and molar absorption changes upon protonation and Hg(II) binding. Spectroscopic and electrochemical results were supported by density functional theory calculations in showing 1a, 2a, and 3 to be low bandgap materials with lowest unoccupied molecular orbitals delocalized over the 1,4-di(pyridin-4-yl)buta-1,3-diyne bridges that provide a pathway for electronic communication between the nitrogens. Overall, the investigations suggest that 1a, 2a, and 3 would be excellent ligands for the construction of novel conjugated hybrid metallosupramolecular nanostructures, polymers, and ion-sensory systems. 相似文献
Ligand exchange method is introduced as an alternative to Job’s and mole ratio methods for studying the stoichiometry of relatively weak metal complexes in solutions. The method involves adding varying amounts of a ligand (L) to an excess constant amount of a colored complex (MX) with appropriate stability and molar absorptivity. The absorbance of each solution is measured at the λmax of the initial complex, MX, and plotted against the concentration of the studied ligand, L. If the newly formed complex ML does not absorb at the λmax of the initial complex, then attenuation of the absorbance of the initial complex on adding varying quantities of the investigational ligand gives an inverse calibration line that intersects with the calibration curve of initial complex at a given point. If a line parallel to the ordinate is drawn from this point to the x-axis, the ratio of the two parts of the x-axis to the left and to the right (α/β) gives the metal to ligand molar ratio in the complex formed, ML. The new method has been applied to the study of the composition of iron (III) complexes with three bisphosphonate drugs: alendronate, etidronate, and ibandronate. The mole ratio was found to be 1:1 with the three investigated bisphosphonates and results were further confirmed by Job’s and mole ratio methods. The ligand exchange method is simpler, quicker, easier to perform and more accurate than Job’s and mole ratio methods for studying weak and relatively weak complexes.