Photocatalytic recovery of metals by Lindqvist-type polyoxometalate–porphyrin copolymer

Hybrid polyoxometalate–porphyrin copolymeric films can be obtained by the electro-oxidation of 5,15-ditolyl porphyrin (H$_{\mathbf{2}}$T$_{\mathbf{2}}$P) and zinc-$\beta$-octaethylporphyrin (ZnOEP) in the presence of the Lindqvist-type polyoxovanadates \mathrm{TBA}_{2}[\mathrm{V}_{6}\mathrm{O}_{13} \lbrace (\mathrm{OCH}_{2})_{3}\mathrm{CNHCO} (4\mbox {-}\mathrm{C}_{5}\mathrm{H}_{4}\mathrm{N})\rbrace _{2}] (Py-V$_{\mathbf{6}}$O$_{\mathbf{13}}$-Py). The photocatalytic properties of these films have been studied for the reduction of silver and platinum ions. In these hybrid materials, porphyrins can be excited by visible light and then play the role of photosensitizers able to give electrons to the polyoxovanadates catalysts

Photocatalytic recovery of metals by Lindqvist-type polyoxometalate–porphyrin copolymer

Hybrid polyoxometalate–porphyrin copolymeric films can be obtained by the electro-oxidation of 5,15-ditolyl porphyrin (H$_{\mathbf{2}}$T$_{\mathbf{2}}$P) and zinc-$\beta$-octaethylporphyrin (ZnOEP) in the presence of the Lindqvist-type polyoxovanadates \mathrm{TBA}_{2}[\mathrm{V}_{6}\mathrm{O}_{13} \lbrace (\mathrm{OCH}_{2})_{3}\mathrm{CNHCO} (4\mbox {-}\mathrm{C}_{5}\mathrm{H}_{4}\mathrm{N})\rbrace _{2}] (Py-V$_{\mathbf{6}}$O$_{\mathbf{13}}$-Py). The photocatalytic properties of these films have been studied for the reduction of silver and platinum ions. In these hybrid materials, porphyrins can be excited by visible light and then play the role of photosensitizers able to give electrons to the polyoxovanadates catalysts

Oxidation of Porphyrins in the Presence of Nucleophiles: From the Synthesis of Multisubstituted Porphyrins to the Electropolymerization of the Macrocycles

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Electrochemical properties of the [SiW 10 O 36 (M 2 O 2 E 2 )] 6− polyoxometalate series (M = Mo( v ) or W( v ); E = S or O)

International audienceElectronic Supplementary Information (ESI) available: FT-IR spectra of the compounds used in this study (Figure S1); Additional electrochemical data (Figure S2-S6), additional UV-Vis-NIR spectroelectrochemistry experiments (Figure S7-S12); effect of addition of an excess of Br2 on the electronic spectra of {SiW10-Mo2O2S2} in DMF (Figure S13); 29 Si NMR spectra of {SiW10-Mo2O2S2} in DMF/CH3CN mixtures before and after addition of one equivalent of Br2 (Figure S14). See This paper deals with the electrochemical studies performed in DMF on three iso-structural and iso-electronic compounds of general formula γ−[SiW10O36(M2O2E2)] 6-, which differ either by the nature of the metallic centers (M = Mo(V) or W(V)) or by the nature of the bridges between Mo(V) atoms (E = O 2-or S 2-). Interestingly, cyclic voltammetry experiments performed in dry DMF reveal electrochemical processes both in oxidation and in reduction modes. The nature of these processes are studied and elucidated by various electrochemical techniques such as coulometry, rotating disk electrodes, spectro-electrochemistry (IR and UV-Vis), NMR and DFT calculations

Paramagnetic Molecular Grippers: The Elements of Six-State Redox Switches

The development of semiquinone-based resorcin[4]arene cavitands expands the toolbox of switchable molecular grippers by introducing the first paramagnetic representatives. The semiquinone (SQ) states were generated electrochemically, chemically, and photochemically. We analyzed their electronic, conformational, and binding properties by cyclic voltammetry, ultraviolet/visible (UV/vis) spectroelectrochemistry, electron paramagnetic resonance (EPR) and transient absorption spectroscopy, in conjunction with density functional theory (DFT) calculations. The utility of UV/vis spectroelectrochemistry and EPR spectroscopy in evaluating the conformational features of resorcin[4]arene cavitands is demonstrated. Guest binding properties were found to be enhanced in the SQ state as compared to the quinone (Q) or the hydroquinone (HQ) states of the cavitands. Thus, these paramagnetic SQ intermediates open the way to six-state redox switches provided by two conformations (open and closed) in three redox states (Q, SQ, and HQ) possessing distinct binding ability. The switchable magnetic properties of these molecular grippers and their responsiveness to electrical stimuli has the potential for development of efficient molecular devices

Synthèse et applications d hybrides de porphyrine-POM pour la dépollution de l'eau par photocatalyse et production d'énergie solaire

ØThe dissertation is presented on 252 content pages which has been framed in five chapters and two annexures while the title page opens into a list of abbreviations followed by a foreword on the work. The core theme of the research work is to validate the extended photocatalytic properties of porphyrin-POM materials in evolving from UV to visible light range of solar spectrum. Which describing additional modes for synthesis of hybrid materials (i) electrostatic multilayer s comprising of Dawson , sandwich Dawson type and preyssler,s POM in combination with free base tetracationic porphyrin [H TPhN(Me) P ] (ii) an easy method of synthesis of two dimers with a pyridinium spacer (abbreviated 4-H Zn and 3-H Zn) (iii) Langmuir Schafer approach for hybrid monolayer. The prepared photoactive thin layers have been characterized by UV-visible spectroscopy and fluorescence spectroscopy for optical properties. Cyclic voltammetry for electrochemistry and ionic permeability studies. Atomic force microscopy (AFM) for surface morphology and its role in physical mechanism of reduction process and shape of nanostructures obtained. Transmission electron microscopy (TEM) has been used to interpret size and shape of dendritic silver nanoparticles obtained as photoreduction product. Although ,the ultimate goal is the photoreduction of heavy metals (Cr(VI), Hg(II), Cd(II), Pb(II) ), reduction of a simpler system like Ag ion has been chosen as a model system due to single electron simpler oxidation reduction process. A novel application of photocurrent generation from these hybrid films has been demonstrated in the fifth chapter of the manuscript as an initial studies which has enhanced the significance of all previously fabricated systems upto by many folds .The foresaid development of photovoltaic application has paved the way for future studies to enhance the photocurrent yield further by tuning the electron donor-acceptor system. Both components porphyrin and POM can be tuned with different axial substituent s and stereo chemical properties to achieve maximum yield of solar energy as well as diversified metal nanostructure for nanoelectronics, e.g. silver dendrites for sensor applications. At the end of the manuscript, three appendices describe successively the experimental techniques used to carry out this work, the Job method used to determine the stoichiometry and formation constants of complex electrostatic and coordination, and then finally the origin or Protocols for the synthesis of various compounds used.PARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF