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<sup>−1</sup>M) 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, <sup>29</sup>Si and <sup>13</sup>C 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 N<sub>2</sub>-physisorption results, xerogels are mesoporous with specific surface area varied from 105 to 312 m<sup>2</sup>g<sup>−1</sup> 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>