Spectral and photochemical properties of hybrid organic—inorganic nanosystems based on CdS quantum dots and a styrylquinoline ligand

Spectral and photochemical properties of hybrid organic–inorganic nanosystems based on CdS quantum dots and merocyanine ligands

“…The average N was 1.0 for HNS-1 and 5.6 for HNS-2. 26,27 The presence of the two different chromophores in the HNSs was confirmed by photoluminescence (PL) measurements (Fig. 2).…”

“…Similar spectral changes were observed previously in the case of QDs irradiation in the region of its absorbance -by the 316 nm and 370 nm light -and were explained by the QDs photodestruction. 27 However, the QDs studied do not absorb visible light, and the model experiment showed that the free QDs do not undergo any changes under 408 and 462 nm irradiation (with the same irradiation times). Hence, under HNSs irradiation by 408 nm light, a sensitized photodestruction of the QDs takes place.…”

“…Apparently, in addition to the trap-state emission, the S trap state population leads to the slow QDs degradation under UV irradiation. 27 Upon HNS irradiation with visible light at the LWAB range, the S trap state may be populated through the S 1_MC state of the adsorbed MC-FL (i.e. through surface charge transfer complexes).…”

“…25,26 We previously reported the spectral and photochemical properties of HNSs containing a styrylquinoline ligand as the FL. 27 No energy transfer from the QDs to the FL was observed in the HNSs, their absorption spectra were limited to the UV range, and their photolysis proceeded in two stagesan initial FL trans-cis photoisomerization with a high quantum yield (QY) and subsequent QDs photodestruction with a significantly lower QY under prolonged irradiation. The structure of the photochromic ligand was changed to shift the absorption spectrum of the HNSs to the visible region providing the spectral overlap of the QDs fluorescence and the ligand absorption and creating a prerequisite for the energy transfer from the QDs to the ligands.…”

Photoactivation, photobleaching and photoetching of CdS quantum dots − Role of oxygen and solvent

“…Once the photoetched QDs are exposed to the light of higher energy (shorter wavelength), photoetching continues. Application of the UV irradiation with wavelength less than 360 nm has been reported to lead not to the gradual photoetching, but photocorrosion to null [15,16], assuming some critical minimum size of photoetched NPs.…”