5-(2-Mercaptoethyl)-1H-tetrazole: Facile Synthesis and Application for the Preparation of Water Soluble Nanocrystals and Their Gels.

A facile method for the preparation of the novel capping ligand 5-(2-mercaptoethyl)-1H-tetrazole for the stabilization of water-soluble nanocrystals was developed. This effective synthetic procedure is based on the cycloaddition of sodium azide to 3,3'-dithiobis(propionitrile) followed by the reductive cleavage of a S-S bond with triphenylphosphine. The structure of the synthesized compound was confirmed by single-crystal X-ray analysis. A target tetrazole was successfully applied for the direct aqueous synthesis of CdTe and Au nanocrystals. CdTe nanocrystals capped with 5-(2-mercaptoethyl)-1H-tetrazole were found to reveal high photoluminescence efficiencies (up to 77 %). Nanocrystals capped with this tetrazole ligand are able to build 3D structures in a metal-ion-assisted gelation process in aqueous solution. Critical point drying of the as-formed hydrogels allowed the preparation of the corresponding aerogels, while preserving the mesoporous structure.