Molecular emitters as a tunable light source for optical multisensor systems

The development of portable and inexpensive analyzers allowing fast determination of the integral sample characteristics is a current trend in analytical chemistry. Optical spectroscopy in visible and near infrared (NIR) range has a great potential due to the advances of modern optical engineering. Optical multisensor systems (OMS) are devices working on the principle of optical spectroscopy, but optimized for a specific analytical task and composed of cheaper elements: light-emitting diodes (LEDs), optical fibers, 3D-printed parts, stamped optics, and etc. Such specialization enables essential reduction of analyzers’ price, size and weight, thus, making the analysis widely available for both real-time application and field measurements.

In the present work, a novel platform for construction of OMS was suggested. The idea is to use a combination of molecular emitters as a multichannel light source with tunable intensity and wavelength range. Cyclometalated Ir(III) complexes [1] and Cu(II)-based complexes were synthetized and tested in order to obtain such a light source. Each individual complex has its own emission spectrum in the visible range. This enables selection and optimization of the light source for a specific analytical application. Several optical setup designs of OMS were developed. The proposed prototype was applied to analyze the metal ions in aqueous mixtures. The practical application of the OMS was demonstrated for the quantification of fluoride and phosphate in real surface and tap waters.

The proposed approach to OMS development allows reducing analysis time and does not require additional sample preparation. Moreover, OMS based on molecular emitters can be adopted for the particular analytical task by selecting the appropriate wavelength region. Despite the relative technical simplicity of OMS, its application in combination with modern chemometric methods provides high accuracy of analysis, comparable with that of full-featured spectrometers.

This study was supported by the RSF project #19-79-00076.

References

[1] Gitlina A.Yu., Surkova A., Ivonina M.V., Sizov V.V., Petrovskii S.K., Legin A., Starova G.L., Koshevoy I.O., Grachova E.V., Kirsanov D.O. Dyes and Pigments, 180 (2020) 108428.