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Nature of gas sensitivity of dyes on the base of Sn(IV) complexes

Doycho Igor K., Gevelyuk Sergiy A., Lepikh Jaroslav I., Rysiakiewicz-Pasek Ewa

Optica Applicata

2019

Vol. 49, nr 3

427--436

Sensitivity of dyes on the base of 4-valence tin complexes to the composition of environment was researched. It has been found out that such dyes by themselves keep stability and inactivity to the composition of atmosphere. However, the photoluminescence properties of the nanostructures on their base can differ sufficiently depending on conditions of their formation. So the glow intensity of the nanoparticle ensembles of dyes having amine substitute in the hydrazonic fragment depends on the concentration of solution which was used during their formation. Optimal concentration exists and its excess leads to weak luminescence due to concentration quenching. Thus, if the nanoparticle ensemble, which was formed at the optimal concentration will be placed into ammonium atmosphere, it will be equivalent to formation of this ensemble by inflated concentration of the saturated solution. So photoluminescence of such system will be weak. Thereby reduced glow intensity will keep sufficiently long time due to the appearance of leakage channels in the form of bridge bonds. In such manner one can register the presence of ammonium in the environment. Initial intensity of luminescence may be re-established by removing extraneous gas with the aid of the short-time low-temperature anneal. In addition, the ligand in the coordination set of the dye plays a part of an interstitial impurity, so its presence leads to certain distribution of the charges in the system. It has been estimated experimentally that less intensive glow corresponds to the charge distribution in the system with the one-dentant ligand, namely by higher content of chlorine ions than in the case of bi-dentant one. This difference is more evident for dyes having hydroxyl substitute in the hydrazonic fragment. Thus, if the nanoparticle ensemble of such dye having a bi-dentant ligand will be placed into the atmosphere containing hydrogen chloride vapours, it changes the charge distribution to the typical one for the dye having one-dentant ligand artificially. It also will lead to weakening of the glow of the system. Initial intensity of luminescence may be re-established by removing the extraneous gas again with the aid of the anneal by the same conditions. The usage of specified properties makes it possible to construct reliable and responsive detectors of ammonium or hydrogen chloride vapours by the change of the detecting element in the known luminescence gas sensors to the nanoparticle ensemble of an appropriate dye.