Donor-Acceptor Properties of Luminophores in Citric Acid and Ethylenediamine-Based Carbon Dots
Anisiya A. Korepanova1, Kirill A. Laptinskiy1, Tatiana A. Dolenko1; 1Lomonosov Moscow State University, Moscow, Russia
Abstract
Currently, in various fields of science, research is being actively conducted aimed at the development of optical nanosensors based on carbon dots (CD) – nanoparticles possessing a unique set of physicochemical properties, notably, intense photoluminescence (PL), sensitive to the change of environment parameters, biocompatibility and dispersibility. Effective use of CD is complicated by the fact that the mechanisms of their photoluminescence formation upon entering the environment are not fully studied, and the structural heterogeneity of the synthesized samples affects their optical properties. For the effective application of CD in nanosensorics, it is important to obtain reliable understanding of their molecular composition and optical properties. This requires the isolation of homogeneous fractions from the initial CD reaction mixture and the subsequent investigation of the environment-dependent changes in the optical properties of each individual fraction.
In the present study, horizontal gel electrophoresis was employed to fractionate CD synthesized via the hydrothermal method from citric acid and ethylenediamine at varying precursor ratios (CD1 with nitrogen deficiency and CD2 with nitrogen excess). Each of the two types of CD samples were separated into 2 fractions: one negatively charged and one neutral. The isolated fractions were dispersed in four solvents characterized by different Catalan acidity (SA) and basicity (SB) parameters. The obtained solutions were investigated using photoluminescence and optical absorption spectroscopy. As a result, the donor-acceptor properties of the isolated fractions were analyzed and compared to those of the initial CD1 and CD2 samples. It was established that during the hydrogen bonds formation with the solvents, the neutrally charged fraction serves as a source of the CD1 acceptor nature, while the negatively charged fraction serves as a source of the CD2 donor nature.
The study was carried out with the support of the Russian Science Foundation grant No. 22-12-00138-П,
https://rscf.ru/project/22-12-00138/.
The work of A.A. Korepanova was supported by the Foundation for the Advancement of Theoretical Physics and Mathematics "BASIS" (Agreement No. 25-2-1-137-1).
Speaker
Anisiya Korepanova
Lomonosov Moscow State University
Russia
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