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Formation and electronic excitation energy transfer process in the nanosystem consisting of CeTbF nanoparticles, cetrimonium bromide (CTAB) surfactant, and chlorin e photosensitizer were studied. It was shown that chlorin e molecules bind to CeTbF NP in the presence of CTAB forming thus CeTbF NP-CTAB-chlorin e nanosystem. We consider that binding occurs via chlorin e embedding in the shell of CTAB molecules, formed around NP. In the CeTbF NP-CTAB-chlorin e nanosystem, electronic excitation energy transfer from Ce to chlorin e takes place both directly (with the 0.33 efficiency for 2 μM chlorin e) and via Tb. [ABSTRACT FROM AUTHOR]

As the step to design nanosystems for X-ray excited sensitizing of singlet oxygen, nanoparticles of polystyrene and polystyrene with encapsulated 2,5-diphenyloxazole were synthesized. Binding of the photosensitizer chlorin e6molecules to both kinds of nanoparticles was shown. Excitation energy transfer from styrene chromophores of polystyrene to the bound chlorin e6molecules occurs in the case of both kinds of nanoparticles. Efficiency of the energy transfer in 2,5-diphenyloxazole-mediated case is higher (0.17) as compared to the non-mediated one (0.12). [ABSTRACT FROM AUTHOR]

Abstract: Photoinduced electronic excitation energy transfer in chromophore complexes is studied by utilizing a mixed quantum classical methodology. Electronic excitations are characterized by a Frenkel-exciton model and treated quantum mechanically while all nuclear coordinates are described classically finally by carrying out room-temperature MD simulations. The theory is applied to the chromophore complex dissolved in ethanol. is formed by a butanediamine dendrimer to which four pheophorbide-a molecules have been covalently linked. The excited electronic states have to be described in an improved exciton model which accounts for charge distributions in the chromophores electronic ground and excited state. It also includes a correct description of the excitonic coupling among different chromophores based on the introduction of atomic centered transition charges. Excitation energy transfer is discussed in using adiabatic exciton states as well as a full solution of the time-dependent Schrödinger equation. To underline the effect of strong excitonic coupling emphasis is also placed on MD runs where two chromophores are positioned close together. Relations are discussed to the standard treatment of exciton dynamics in using the density matrix theory as well as by introducing rate equations based on rate expressions according to Förster. [Copyright &y& Elsevier]

The processes of electronic excitation energy transfer (EEET) between different types of dye molecules inserted into the matrix of a porous glass have been investigated. An extreme character of the dependence of the EEET efficiency on the size of pores has been revealed. The dependence of the fractal dimensionality of the distribution of dye molecules on the sizes of the pores has been determined. [ABSTRACT FROM AUTHOR]

Polystyrene (PS)-diphenyloxazole (PPO) nanoparticles with attached cross-linked poly-N-isopropylacrylamide (PNIPAM) chains were obtained resulting in PS-PPO-PNIPAM hybrid nanosystems (NS). Fluorescence spectra of chlorin e6 added to PS-PPO-PNIPAM hybrid NS revealed electronic excitation energy transfer (EEET) from PS matrix and encapsulated PPO to chlorin e6. EEET efficiency increased strongly during 1 h after chlorin e6 addition, indicating that uptake of chlorin e6 by PNIPAM part of hybrid NS still proceeds during this time. Heating of PS-PPO-PNIPAM-chlorin e6 NS from 21 to 39 °C results in an enhancement of EEET efficiency; this is consistent with PNIPAM conformation transition that reduces the distance between PS-PPO donors and chlorin e6 acceptors. Meanwhile, a relatively small part of chlorin e6 present in the solution is bound by PNIPAM; thus, further studies in this direction are necessary. [ABSTRACT FROM AUTHOR]