Synthesis ans structural studies of a new class of heterocyclic compounds: 1,2,4-pyridothiadiazine 1,1-dioxides, pyridyl analogues of 1,2,4-benzothiadiazine 1,1-dioxides

in Tetrahedron (1995), 51

Synthesis by sol-gel process of visible light sensitive-TiO2 for the degradation of pollutants and microorganisms

Poster (2011)

Since the discovery of photocatalytic decomposition of water on TiO2 electrodes by Fujishima and Honda [1], heterogenous photocatalysis has been widely studied for environmental applications ... [more ▼]

Since the discovery of photocatalytic decomposition of water on TiO2 electrodes by Fujishima and Honda [1], heterogenous photocatalysis has been widely studied for environmental applications. Photocatalytic processes are new technologies for waste water treatment because new compounds (alkanes, pesticides, dyes, etc.) in effluents are not readily degraded by the conventional treatments [2]. Oxidative processes can completely destroy organic pollutants [3] or microorganisms (bacteria, viruses, fungi, etc.) [4,5]. At this moment, the commercial Degussa P25 is the mostly used photocatalyst. Nevertheless, it requires UV light to be activated, that is why scientists try to activate TiO2 under visible light. The aim of this study is to synthesize photocatalysts activated by visible light and to evaluate their activity for the degradation of pollutants and microorganisms. The sol-gel process allows the direct introduction of visible light sensitive species like porphyrins inside the TiO2 matrix during the synthesis [6]. Two tetracarboxyphenyl porphyrins are synthesized for the sensitization of TiO2 to visible light : the metal free tetracarboxyphenyl porphyrin and the nickel tetracarboxyphenyl porphyrin. These porphyrins are characterized by 1H NMR, FT-IR and UV/Vis spectroscopies. They are introduced during the sol-gel synthesis of TiO2 matrix. Diffuse reflectance and FT-IR spectroscopies are used to ensure that porphyrins are incorporated inside the matrix of TiO2. Indeed, characteristic porphyrins peaks appear on spectra. The cristallinity and specific surfaces of catalysts are also determined by XRD and nitrogen adsorption-desorption measurements respectively. The depolluting efficiency of photocatalysts is evaluated for the degradation in water of p-nitrophenol, which is listed as one of the 114 organic pollutants by the Environmental Protection Agency in the US. After 6 h under visible light, 40 % of p-nitrophenol are degraded with some catalysts. The activity is influenced by i) the presence of porphyrins : the photoactivity increases with the amount of porphyrins ; ii) the nature of porphyrins : nickel porphyrins are more active than free metal porphyrins ; and iii) the crystallinity of catalysts : amorphous catalysts are less active than crystallized samples. The photocatalysts with the highest degradation rating of dyes will be selected for the degradation in water of Escherichia coli and Lactobacillus acidophilus. [1] A. Fujishima, K. Honda, Nature 238, 37-38 (1972) [2] P. Gogate, A. Pandit, Advances in Environmental Research 8, 501-551 (2004). [3] D. Chen, A. Ray, Water Research 32, 3223-3234 (1998) [4] R. Watts, S. Kong, M. Orr, G. Miller, B. Henry, Water Research 29, 95-100 (1995). [5] J. Hong, M. Otaki, Journal of Bioscience and Bioengineering 101, 185-189 (2006). [6] C. Wang, J. Li, G. Mele, G.M. Yang, F.-X. Zhang, L. Palmisano, G. Vasapollo, Applied catalysis 78, 218-226 (2007). [less ▲]

Synthesis of (Na1-xLix)MnFe3+2(PO4)3 (with x = 0 to 1) compounds with the alluaudite structure type : the crystallochemical role of lithium

in Terra Nova (1998), 10

Synthesis of 1-vinyl-3-ethylimidazolium-based ionic liquid (co)polymers by cobalt-mediated radical polymerization

in Macromolecules (2011), 44(16), 6397-6404

The cobalt-mediated radical polymerization (CMRP) of 1-vinyl-3-ethylimidazolium bromide (VEtImBr) is described. Polymerizations were performed at 30 °C in solution either in dimethylformamide (DMF) or in ... [more ▼]

The cobalt-mediated radical polymerization (CMRP) of 1-vinyl-3-ethylimidazolium bromide (VEtImBr) is described. Polymerizations were performed at 30 °C in solution either in dimethylformamide (DMF) or in methanol (MeOH) or in a mixture of both solvents, using a preformed alkyl–cobalt(III) adduct, CH3OC(CH3)2CH2–C(CH3)(CN)–(CH2–CHOAc)<4–Co(acac)2, as the mediating agent. Excellent control over molecular weights and dispersities (Mw/Mn 1.05–1.06) was achieved in MeOH, with a linear increase of experimental molecular weights with the monomer conversion. Substituting methanol for DMF induced much faster polymerization process, even under quite high diluted conditions: for instance, about 80% monomer conversion was reached in 30 min in DMF, compared to 10 h in MeOH. However, size exclusion chromatography (SEC) traces of PVEtImBr samples synthesized in DMF revealed a side population in the high molecular weight region, presumably due to the occurrence of irreversible coupling reactions of a small proportion of growing chains. Well-defined diblock copolymers featuring both a poly(vinyl acetate) (PVAc) block and a PVEtImBr-based poly(ionic liquid) block, PVAc-b-PVEtImBr, were next obtained by sequential CMRP of VAc and VEtImBr. To this end, a PVAc-Co(acac)2 was first prepared by CMRP and employed as a macroinitiator for the polymerization of VEtImBr either in methanol or in a mixture of DMF and MeOH (2/1: v/v) at 30 °C. Finally, cobalt-mediated radical coupling (CMRC) of the aforementioned PVAc-b-PVEtImBr diblock copolymers, using isoprene as a simple coupling agent, led to unprecedented and structurally well-defined PVAc-b-PVEtImBr-b-PVAc triblock copolymers. [less ▲]

Synthesis of 2-aminoquinazoline-4(3H)-one derivatives as potential potassium channel openers

in Journal of Heterocyclic Chemistry (2000), 37

The synthesis of 6-[18F]fluoro-L-dopa by chiral catalytic phase-transfer alkylation.

in Journal of Labelled Compounds & Radiopharmaceuticals (1999), 42

Synthesis of [18F]FDG with alkaline hydrolysis on a low polarity solid phase support.

in Journal of Labelled Compounds & Radiopharmaceuticals (1997), 40

Synthesis of [Gamma-32p]Thiamine Triphosphate

in Analytical Biochemistry (1988), 169(2), 274-278

We developed a novel chemical synthesis of thiamine triphosphate which allows us to incorporate 32P in the gamma position. The reaction is based on the condensation of [32P]orthophosphoric acid and ... [more ▼]

We developed a novel chemical synthesis of thiamine triphosphate which allows us to incorporate 32P in the gamma position. The reaction is based on the condensation of [32P]orthophosphoric acid and thiamine diphosphate in the presence of ethyl chloroformate. After purification by two ion-exchange purification steps, the thiamine derivative has a specific radioactivity of 10 Ci/mmol. The average final yield synthesis is about 10%. [less ▲]

Synthesis of a series of 4H-1,2,4-pyridothiadiazine 1,1-dioxides and their evaluation as new potassium channel openers

Conference (1994, March)

Synthesis of a simplified bryostatin C-ring analogue that binds to the CRD2 of human PKC-alpha and construction of a novel BC-analogue by an unusual Julia olefination process

in Organic Letters (2003), 5(4), 499-502

[GRAPHICS] The synthesis of two truncated bryostatin analogues 2 and 3 is described. High-field NMR measurements on the C-ring analogue 3 in (CH3CN)-H-2 containing 25% (H2O)-H-2 have shown that it binds ... [more ▼]

[GRAPHICS] The synthesis of two truncated bryostatin analogues 2 and 3 is described. High-field NMR measurements on the C-ring analogue 3 in (CH3CN)-H-2 containing 25% (H2O)-H-2 have shown that it binds to the CRD2 of human PKC-alpha at virtually the same position as phorbol-13-acetate (PA) and bryostatin 1 (1). NMR titration studies have also revealed that 3 binds to the CRD2 with a potency similar in magnitude to PA but much less potently than 1. [less ▲]