The Luminescence Properties and Intramolecular Energy Transfer of Rare Earth Complexes with Aromatic Carboxylic Acids

The triplet state energies of para aminobenzoic acid and nicotinic acid were determined by means of low temperature phosphorescence spectrometry. The energy matches between them and the resonant emitting energy levels of Eu 3+ , Tb 3+ , Sm 3+ , Dy 3+ were studied. The intramolecular energy transfer processes from the two aromatic carboxylic acid ligands to rare earth ions were also discussed on the basis of the measurement results of luminescence intensities, lifetimes and quantum efficiencies.

Phonon-assisted excitation energy transfer in photosynthetic systems

The phonon-assisted process of energy transfer aiming at exploring the newly emerging frontier between biology and physics is an issue of central interest.This article shows the important role of the intramolecular vibrational modes for excitation energy transfer in the photosynthetic systems.Based on a dimer system consisting of a donor and an acceptor modeled by two two-level systems,in which one of them is coupled to a high-energy vibrational mode,we derive an effective Hamiltonian describing the vibration-assisted coherent energy transfer process in the polaron frame.The effective Hamiltonian reveals in the case that the vibrational mode dynamically matches the energy detuning between the donor and the acceptor,the original detuned energy transfer becomes resonant energy transfer.In addition,the population dynamics and coherence dynamics of the dimer system with and without vibration-assistance are investigated numerically.It is found that,the energy transfer efficiency and the transfer time depend heavily on the interaction strength of the donor and the high-energy vibrational mode,as well as the vibrational frequency.The numerical results also indicate that the initial state and dissipation rate of the vibrational mode have little influence on the dynamics of the dimer system.Results obtained in this article are not only helpful to understand the natural photosynthesis,but also offer an optimal design principle for artificial photosynthesis.

Photophysical Properties of Rare Earth Complexes with 3,4-Furandicarboxylic Acid and 1,10-Phenanthroline

Synthesis, IR spectra, UV vis spectra and photophysical properties of Gd 3+ , Eu 3+ , Tb 3+ complexes with 3,4 furandicarboxylic acid and 1,10 phenanthroline are reported. Intramolecular energy transfer process for these complexes is discussed in detail. It is found that the intramolecular energy transfer efficiency depends on the relative positions between the resonance energy levels of the central rare earth ions and the lowest triplet state energies of ligands.

BLUE LIGHT-EMITTING POLY(FLUORENE-CO-BENZENE) CONTAINING AN OXADIAZOLE MOIETY

A new kind of polyfluorene containing oxadiazole as the side chain was synthesized. The introduction of oxadiazole moiety as more bulky group prevents the aggregation and reduces the crystallinity of the polymers. Efficient intramolecular energy transfer from oxadiazole moiety to the conjugated backbone has been realized, leading to 70% improvement of photoluminescence quantum efficiency of the designed polymers. Compared with PAF, the PFOXD exhibits significant improvement in electroluminescence properties, with luminous efficiency of 0.8 cd/A and maximum luminance of 1800 cd/m2.

Effects of Gd^(3+) on Luminescence Properties of Eu^(3+) within Polymeric Structure in Aqueous Solutions

?6′ tetracarboxy 4,4′ bipyridine was synthesized and the luminescence enhancement of their Eu 3+ complexes by Gd 3+ was observed. The results indicate that the mechanism of enhancement is based on the formation of a polymeric structure where Eu 3+ and Gd 3+ are linked together by the ligands, which favours the consequent transfer of absorbed energy along the polymeric chain through several ligands toward the Eu 3+ .

Hydrogen peroxide-activatable iodoBodipy-phthalhydrazid conjugate nanoparticles for cancer therapy

The dependence on outer light source strongly hinders clinical applications of photodynamic therapy(PDT)to the deep-seated tumor.However,the majority of documented PDT systems that function without the external light source rely on either the chemiluminescence resonance energy transfer(CRET)or fluorescence resonance energy transfer(FRET)mechanism,which decreases the energy transfer efficiency and reproducibility of PDT.Herein,we developed a novel single-molecule triplet photosensitizer(iodoBodipy(IBDP)-L)that can be chemiexcited to triplet excited state to generate reactive oxygen species instead of outer light irradiation.The direct bonding of phthalhydrazid moiety to iodoBodipy fluorophore evoked valid intramolecular energy transfer(IET),and once phthalhydrazid part is activated by hydrogen peroxide,the released reaction energy could excite the iodoBodipy-phthalhydrazid conjugate as a whole.Reaction product IBDP-L-COOH showed high triplet state quantum yield(ΦT=65%)and large spin-orbit coupling.A large amount of reactive oxygen species(ROS)was produced in MCF-7 cells,thus inhibiting the cell growth both in vitro and in vivo after IBDP-L was formulated into nanoparticles(NPs)via nanoprecipitation.We believe that the synthesized IodoBodipy-phthalhydrazid conjugate based on the IET mechanism will open a new door in the molecular design of efficient triplet photosensitizers for treating deeply seated tumors in the future.

Influence of bidentate structure of an aryl phosphine oxide ligand on photophysical properties of its Eu~Ⅲ complex

The bidentate phosphine oxide ligand 1,8-bis(diphenylphosphino) naphthalene oxide (NAPO) and its EuⅢ complex 1 Eu(TTA)3(NAPO) (TTA=2-thenoyltrifluoroacetonate) were chosen to study the effect of bidentate phosphine oxide ligand on the photophysical properties of the corresponding complex. The intramolecular energy transfer processes of 1 were studied. The investigation showed that with bidentate structure NAPO could suppress solvent-induced quenching by enforcing the ligand-ligand interaction and the rigidi...