Energy Transfer and Electron Transfer Distances in Heteropolysilane Langmuir−Blodgett Films

Abstract

Energy transfer distances from polysilanes bearing alkyl groups to those bearing aromatic groups are estimated by employing heteropolysilane Langmuir−Blodgett (LB) films. In the heteropolysilane films, AL1-LB film (10 layers, poly((hydroxyhexyl)hexylsilane))/I1-LB film (n layers, insulator polymer, (isobutyl methacrylate))/AR1-LB film (10 layers, poly((hydroxyphenyl)butylsilane)), AL1 is selectively excited with 310 nm light and the fluorescence from AR1-LB film is observed, as the number of insulator layers, n, is changed. The results imply that energy does not transfer from AL1-LB film to AR1-LB film when two insulator LB layers (22 Å) are inserted between the two polysilane LB films. The electron transfer distances from polysilanes to (2,2‘-(2-(cholan-24-yl)-2,5-cyclohexadiene-1,4-diylidene)bis(propanedinitrile) (TCNQ1) are also estimated by employing a heteropolysilane LB film, AL1-LB film (10 layers)/I1-LB film (insulator, n layers)/TCNQ1-LB film (10 layers). The electron transfer distance from AL1-LB film to TCNQ1-LB film is determined by observing the decomposition of AL1 (the decrease in the UV absorption) when TCNQ1-LB film is selectively exposed to UV light. It is estimated that electron transfer from AL1-LB film to TCNQ1-LB film occurs through insulators of less than 22 Å thickness.

Electronic Energy Transfer in Oriented Bilayer Films of Polysilanes

“…The fluorescence quenching of a monomethin-oxacyanine dye by monomethin thiacyanine was studied in the LB films, and the intermolecular energy transfer between dyes was shown to occur on a scale of 10 nm. The energy transfer distance between the two polysilane layers was estimated to be less than 2.2 nm, from the measurement of fluorescence spectra of heteropolysilane LB films having an insulator layer. A single-step energy transfer cannot explain the long migration distance in the PMOdS layer, but the excitons migrate in the wide range of the PMOdS layer by multistep hopping.…”

“…[15][16][17] The energy transfer distance between polysilane layers was examined by employing heteropolysilane Langmuir-Blodgett (LB) films. 15 It was estimated that energy was transferred from a poly(alkylsilane) layer to a poly(arylsilane) layer through an insulator layer thinner than 2.2 nm. The fluorescence spectroscopy of the blends of polysilane was discussed in relation to the miscibility of the blends.…”

“…The possibility of intermolecular energy transfer has been studied using bicomponent materials consisting of polysilanes having different substituents. − The energy transfer distance between polysilane layers was examined by employing heteropolysilane Langmuir−Blodgett (LB) films . It was estimated that energy was transferred from a poly(alkylsilane) layer to a poly(arylsilane) layer through an insulator layer thinner than 2.2 nm.…”

Photosensitization of Base-Developable Poly(phenylhydrosilane) with 3,3‘,4,4‘-Tetra(tert-butylperoxycarbonyl)benzophenone. Mechanism of the Drastic Photosensitization in Terms of Photoinduced Electron Transfer

“…The fluorescence quenching of 2 in the presence of EA1 fitted the Perrin formalism better than the Stern−Volmer fitting, as shown in Figure , and the active sphere volume was calibrated to be 1.63 × 10 11 Å 3 (radius 3400 Å). The value is too large, because perchloropentacyclododecane has been reported to quench the fluorescence of 2 with the v value 10 000 Å 3 (radius 13 Å). , We have reported that photoinduced electron transfers from polysilane LB films to photoexcited TCNQ LB films did not occur over a distance of 50 Å when polyacrylate LB films were incorporated between the polysilane LB film and the TCNQ LB film …”

“…34,35 We have reported that photoinduced electron transfers from polysilane LB films to photoexcited TCNQ LB films did not occur over a distance of 50 Å when polyacrylate LB films were incorporated between the polysilane LB film and the TCNQ LB film. 47 Let us presume why EA1 and EA2 show anomalous behavior for fluorescence quenching of polysilane 2, compared with those of other additives previously reported. 34,35 There are a few reports on photosensitizations of peroxides.…”