Columinescence of dye molecules in nanostructures of metal ion complexes

Cofluorescence of dyes in nanoparticles formed from metal complexes and possibilities of its application

“…NPs from complexes exist in the range of complex concentrations from 10 -7 to 1 × 10 -5 M for most of the investigated aqueous solutions and the solution remains transparent despite the growth of I cofl of the dyes, which accompanies the growth in NP size and overcomes the growth of I fl of the complexes [13]. It was shown in [9,14] that, similarly to the I colum of the luminescent Ln(III) ions in NPs [15][16][17][18], the I cofl of the dyes in NPs depends on the point in time when the dye was introduced in the solution.…”

“…The tails of the wide fluorescent spectra of the complexes, however, interfere with the detection of the limiting low quantities of dyes in the case of the intensely fluorescent Al or Sc complexes. The efficient sensitization of the R6G molecules in NPs from the low fluorescent complexes of heavy metals make it possible to expect that in these NPs the availability of fluorescence tails of the complexes in the area of the R6G fluorescence maximum would be less interfering in the detection of low R6G concentra tions in a solution compared with NPs from Al com plexes [13,19]. The changes in the fluorescence inten sity ratio of Lu(DBM)3phen and R6G on the change of the R6G molecule concentration in the initial aqueous solution from 0.05 to 1.0 nM were investi gated in aqueous solutions 10 μM Lu(III) + 30 μM DBM + 10 μM phen.…”

“…The fluorescence sensitization of the captured dyes occurs by the light quanta (which are absorbed by the metal complexes) being incorporated into NPs; hence, a phenomenon is observed that could be called dye cofluorescence (similarly to Ln columinescence). It was established later [11][12][13][14] that NPs from the lan thanide and other trivalent metal (Al(III), Sc(III), In(III), Y(III)) complexes exist with the incorporated neutral (Nile Red (NR), coumarin 30) and anionic (eosin, fluorescein) dye molecules. The configuration of NPs from metal complexes with incorporated dyes can be illustrated by the schematic model presented in Fig.…”

“…By comparing the cofluorescence intensity (I cofl ) of the Nile Blue (NB) in NPs from Gd or Lu complexes with NPs from Eu(III), it was established that the effi ciency of NB sensitization due to the singlet excitation energy migration from the Eu(III) ions to it is lower than due to the energy transfer from the Eu(III) ions at a dye concentration in water below 100 nM and that the S-S energy transfer competes successfully with the NB sensitization by Eu(III) ions at the higher dye concentrations [10,13].…”

“…An investigation into the dependence of the area of the existence of dye cofluorescence on the metal ion concentration in aqueous solution of ligands (beta diketones, 1,10 phenantroline) [13] confirmed the conclusion that NPs are formed which capture lumi nescence ion complexes or dye molecules from the solution starting from the complex concentration of 1 × 10 -7 M. The dye fluorescence sensitization (cof luorescence) in NPs is accompanied by the fluores cence quenching of the organic part of complexes like, for example, in the case of NPs from Al(III), Sc(III), In(III) complexes [11] or by the luminescence quenching of the lanthanide ion like in the case of the complex with Eu(III) ions [10]. For the NPs from Al(III), Sc(III), In(III) complexes this phenomenon is determined by the capture of the singlet exciton migrating between complexes by the dye in NPs, and for the NPs from the Eu complexes the sensitization of the fluorescence of the dyes with the fluorescent S 1D level below the responance 5 D 0 level of Eu(III) occurs by both the singlet exciton capture and by the energy transfer from the excited Eu(III) level (Fig.…”