Synthesis of new silica xerogels based on bi-functional 1,3,4-thiadiazole and 1,2,4-triazole adducts

<p>New transparent Silica-based hybrid materials were synthesized by reaction of polymethylhydrosiloxane (PMHS) and organic compounds: 1,3,4-thiadiazole-2,5-diamine <b>(1)</b>, 1,3,4-thiadiazole-2,5-dithiol <b>(2)</b> and 1H-1,2,4-triazole-3-thiol <b>(3)</b>, in tetrahydrofuran as solvant using hexachloroplatinic acid (H₂PtCl₆.6H₂O) as a catalyst. PMHS was used as a principal network forming agent, it has been cross-linked via hydrosilylation reaction with bi-functional heterocyclic compounds, leading to the formation of colored gels. These later dried (xerogels) were characterized by numerous techniques, including spectroscopy of (FT–IR) and ¹³C and ²⁹Si CP MAS NMR. The xerogels morphology and texture were studied by scanning electron microscopy and Brunauer–Emmet–Teller method. According to N₂-physisorption results, isotherms are classified as type IV with H₂ type hysteresis loop; then, the xerogels are mesoporous materials. The optic and magnetic properties of the obtained materials were studied by UV–VIS and EPR spectroscopies, respectively. This study showed that all materials are paramagnetic semiconductors.</p

New silica hybrids elaborated by sol-gel process from bifunctional thiadiazole and 1,2,4-triazole precursors

<p>New hybrid materials were synthesized from an inorganic precursor, (tetraethoxysilane: TEOS) and bifunctional organic precursors through the sol-gel process. Indeed, monolithic and transparent hybrid gels were obtained by the reaction of tetraethoxysilicate (TEOS) with 1,2,4-thiadiazole-3,5-diamine <b>(1)</b>, 5-amino-1,3,4-thiadiazole-2-thiol <b>(2)</b>, and 1H-1,2,4-triazole-3-thiol <b>(3)</b> in ethanol as solvent, using chloric acid (HCl 10⁻¹M) as catalyst. It is shown that TEOS has been cross-linked with bi-functional heterocyclic compounds: <b>(1), (2)</b> and <b>(3)</b> leading to the formation of transparent and colorous gels. The characterization was realized by infrared, ²⁹Si and ¹³C CP MAS NMR. The xerogels morphology and texture were studied by scanning electron microscopy (SEM) and Brunauer – Emmet – Teller method (BET). The obtained results show that organic adducts <b>(1), (2)</b> and <b>(3)</b> react with TEOS leading to gels in which Si–N and Si–S bridges were formed. According to N₂-physisorption results, xerogels are mesoporous with specific surface area varied from 105 to 312 m²g⁻¹ and their isotherms are classified as type IV. The optic and magnetic properties of hybrids were studied respectively by UV-Vis spectroscopy and RPE. This study showed that all materials are paramagnetic semiconductors.</p

New silica-based hybrid materials (Nouveaux matériaux hybrides à base de silicium)

<p></p> <p>New hybrid organic-inorganic materials have been obtained by reactions at room temperature of polymethylhydrosiloxane (PMHS) with different organic bi-functional molecules, in tetrahydrofuran (THF) using hexachloroplatinic acid (H₂PtCl₆.6H₂O) as a catalyst. These reactions have led to the formation of monolithic colored and transparent polymeric gels. The characterization of xerogels has been carried by infrared, ²⁹Si and ¹³C CP MAS NMR and thermal analysis DTA-TGA. Xerogels morphology and texture were studied by scanning electron microscopy (SEM) and Brunauer–Emmet–Teller method (BET). The obtained results show that organic molecules react with PMHS leading to gels in which Si–N and Si–O covalent bridges are formed. The optic and magnetic properties of hybrid gels are studied respectively by UV-Vis spectroscopy and RPE. The obtained results show that materials are paramagnetic semiconductors.</p