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The article presents a method for the construction of a new tricyclic system of imidazo[1,2-b]pyrido[4,3-e][1,2,4]triazin-6(7Н)-ones based on subsequent reactions of the obtained 1,2-diamino-4-phenylimidazole ethyl ether of 3-methyl-6-phenylimidazo[1,2-b][1,2,4]triazin-2-carboxylic acid with dimethylformamide dimethyl acetal and primary amines. The structures of the obtained compounds were confirmed using the data obtained from 1 Н and 13 С NMR, HRMS, and XRD analyses. We analyzed the dependence of the absorption and photoluminescence spectra on the structure of the compounds obtained using quantum chemistry methods. The theoretical results were compared with the data from a real experiment. The article suggests a range of practical applications for imidazo[1,2-b]pyrido[4,3-e][1,2,4]triazin-6(7Н)-ones., (© 2022 John Wiley & Sons Ltd.)

A technique of obtaining plexitonic structures based on Ag 2 S quantum dots passivated with l-cysteine (Ag 2 S/l-Cys QDs) in the presence of Au nanorods passivated with cetyltrimethylammonium bromide molecules (Au/CTAB NRs) with controlled luminescence properties has been developed. The structural and luminescence properties of Ag 2 S/l-Cys QDs with Au/CTAB NRs are studied. The effect of plasmonic Au/CTAB NRs on IR trap state luminescence (750 nm) is considered. It has been found that the direct interaction between the components of the plexcitonic nanostructure leads to a significant luminescence quenching of Ag 2 S/l-Cys QDs, with the luminescence lifetime being constant. This is the evidence for photoinduced charge transfer. The spatial separation of the components of plexcitonic nanostructures due to the introduction of a polymer - poly(diallyldimethylammonium chloride) (polyDADMAC) provides a means to change their mutual arrangement and achieve an increase in the IR trap state luminescence intensity and a decrease in the luminescence lifetime from 7.2 ns to 4.5 ns. With weak plexcitonic coupling in the nanostructures [Ag 2 S QD/l-Cys]/[polyDADMAC]/[Au/CTAB NRs], the possibility of increasing the quantum yield of trap state luminescence for Ag 2 S QDs due to the Purcell effect has been demonstrated. In the case of formation [Ag 2 S QD/l-Cys]/[polyDADMAC]/[Au/CTAB NRs] a transformation of shallow trap state structure was established using the thermostimulated luminescence method., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The regularities of the electron excitations exchange in hybrid associates of colloidal Ag 2 S quantum dots, passivated with thioglycolic acid (Ag 2 S/TGA QDs) with an average size of 2.2 and 3.7 nm with Indocyanine Green J-aggregates (ICG) were studied in this work by methods of absorption and luminescence spectroscopy. It was shown that IR luminescence sensitization of Ag 2 S/TGA QDs with an average size of 3.7 nm in the region of 1040 nm is possible due to non-radiative resonance energy transfer from Ag 2 S/TGA QDs with an average size of 2.2 nm and luminescence peak at 900 nm using ICG J-aggregate as an exciton bridge. The sensitization efficiency is 0.33. This technique provides a transition from the first therapeutic window (NIR-I, 700-950 nm) to the second (NIR-II, 1000-1700 nm). It can allow high to increase the imaging in vivo resolution.

In this paper, we present the results on photoinduced formation of colloidal Ag 2 S quantum dots with sizes of 1.5-3 nm passivated by 2-mercaptopropionic acid (Ag 2 S/2-MPA) in the presence of ethylene glycol. The synthetized colloidal Ag 2 S/2-MPA QDs have NIR recombination luminescence with its maximum near 800 nm. The control of absorption and luminescence properties of the QDs is achieved by photoactivation. It is shown that photoexposure of colloidal solution of Ag 2 S/2-MPA QDs leads to an increase in the QD size and monodispersity along side with the growth of the luminescence quantum yield from 1% to 7.9%. Enhancement of the luminescence quantum yield is accompanied by an increase in the average luminescence lifetime up to 190 ns, which is due to the blocking of the nonradiative recombination channel with the radiative recombination rate being (3-5.5) × 10 5 s -1 . It is shown that the purification of the Ag 2 S/2-MPA solution by a dialysis membrane from regenerated cellulose leads to an increase in the sample monodispersity, as well as stops the photoinduced growth of QDs, and also reduces the degradation of their photoluminescence., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)