Photophysical Properties of 4t-（p-aminophenyl）-2,2＇：6＇,2″-terpyridine

Spectral and photophysical investigations of 4＇-（p-aminophenyl）-2,2＇：6＇,2″-terpyridine （APT） have been performed in various solvents with different polarity and hydrogen-bonding ability. The emission spectra of APT are found to exhibit dual fluorescence in polar solvents, which attributes to the local excited and intramolecular charge transfer states, respectively. The two-state model is proven out for APT in polar solvent by the time-correlated single photon counting emission decay measurement. Interestingly, the linear relationships of different emission maxima and solvent polarity parameter are found for APT in protic and aprotic solvents, because of the hydrogen bond formation between APT and alcohols at the amino nitrogen N25. Furthermore, the effects of the complexation of the metal ion with tpy group of APT and the hydrogen bond formation between APT with methanol at the terpyridine nitrogen N4-NS-N14 are also presented. The appearance of new long-wave absorption and fluorescence bands indicates that a new ground state of the complexes is formed.

Photophysical Property of Photoactive Molecules with Multibranched Push-Pull Structures

The structure-property characteristics of a series of newly synthesized intramolecular charge- transfer （ICT） compounds, single-branch monomer with triphenylmethane as electron donor and 2,1,3-benzothiadiazole as acceptor, the corresponding two-branch dimer and three- branch trimer, have been investigated by means of steady-state and femtosecond time- resolved stimulated emission fluorescence depletion （FS TR-SEP FD） techniques in different polar solvents. The TD-DFT calculations are further performed to explain the observed ICT properties. The interpretation of the experimental results is based on the comparative studies of the series of compounds which have increased amount of identical branch moiety. The similarity of the absorption and fluorescence spectra as well as strong solvent-dependence of the spectral properties for the three compounds reveal that the excited state of the dimer and trimer are nearly the same with that of the monomer, which may localize on one branch. It is found that polar excited state emerged through multidimensional intramolecular charge transfer from the donating moiety to the acceptor upon excitation, and quickly relaxed to one branch before emission. Even so, the red-shift in the absorption and emission spectra and decreased fluorescence radiative lifetime with respect to their monomer counterpart still suggest some extent delocalization of excited state in the dimer and trimer upon excitation. The similar behavior of their excited ICT state is demonstrated by FS TR-SEP FD measurements, and shows that the trimer has the largest charge-separate extent in all studied three samples. Finally, steady-state excitation anisotropy measurements has further been carried out to estimate the nature of the optical excitation and the mechanism of energy redistribution among the branches, where no plateau through the ICT band suggests the intramolecular excitation transfer process between the branches in dimer and trimer.

Effect of chloride introduction on the optical properties in Eu^(3+)-doped fluorozirconate glasses

Fluorozirconate glass containing Euions and chloride ions are prepared by a meltquenching method. The luminescence behavior of Euaffected by Cl ions is investigated. With increasing Cl ion concentration, the luminous intensity of Euis significantly enhanced and the quantum efficiency of fluorozirconate glass is improved. Meanwhile, the intensity parameter ?increases according to the Judd–Ofelt calculation, which indicates the decrease of local symmetry. The average lifetime of Euincreases by introducing the Cl ions. Moreover, we find two kinds of sites for Euions in a glass network by analyzing the fluorescence decay. The distribution of Euions changes with increasing Cl ion concentration.In addition, the excessive Cl ions lead to the separation of the glass phase and the formation of the crystal phase, thus reducing the transmittance dramatically.

Changes of Photosystem Ⅱ Electron Transport in the ChlorophyⅡ-deficient Oilseed Rape Mutant Studied by ChlorophyⅡ Fluorescence and Thermoluminescence

The photosystem Ⅱ （PSII） complex of photosynthetic membranes comprises a number of chlorophyll-binding proteins that are important to the electron flow. Here we report that the chlorophyll b-deficient mutant has decreased the amount of light-harvesting complexes with an increased amount of some core polypeptldes of PSII, including CP43 and CP47. By means of chlorophyll fluorescence and thermolumlnescence, we found that the ratio of Fv/Fm, qP and electron transport rate in the chlorophyll b-deficient mutant was higher compared to the wild type. In the chlorophyll lPdeflclent mutant, the decay of the primary electron acceptor quinones （QA-） reoxidation was decreased, measured by the fluorescence. Furthermore, the thermoluminescence studies in the chlorophyll bdeficient mutant showed that the B band （S2/S3QB-） decreased slightly and shifted up towards higher temperatures. In the presence of dlchlorophenyl-dlmethylurea, which is inhibited in the electron flow to the second electron acceptor quinines （QB） at the PSll acceptor side, the maximum of the Q band （S2QA-） was decreased slightly and shifted down to lower temperatures, compared to the wild type. Thus, the electron flow within PSll of the chlorophyⅡ b-deficient mutant was down-regulated and characterized by faster oxidation of the primary electron acceptor quinine QA-via forward electron flow and slower reduction of the oxidation S states.

Synthesis, Structure, Fluorescence and Magnetic Properties of a New Binuclear Cobalt (Ⅱ) Complex Containing Three Kinds of Ligands

A new binuclear cobalt(Ⅱ)complex,[Co2(C10H6NO2)2(C12H8N2)2(N3)2]·H2O(1,C10H6NO2-:isoquinoline-1-carboxylate,C12H8N2:1,10-phenanthroline(phen);N3-:azide),has been synthesized though a mixed-solvothermal method using the pentanol and distilled water as solvent.The complex was characterized by elemental analysis,IR spectrum and single-crystal X-ray diffraction.It crystallizes in triclinic system,space group P1 with Z=2,a=1.777(5),b=11.815(5),c=17.141(7)?,α=74.496(6)°,β=70.537(6)°,γ=67.861(6)°,V=2055.4(14)?3,Mr=922.66,Dc=1.491 g/cm3,λ=0.71073?,μ=0.870 mm-1,F(000)=942,R=0.0455 and wR=0.1147 for 4960 observed reflections with I>2σ(I)and S=1.129.Its molecular structure is constructed by two Co2+cations,two chelating phen ligands,two chelating isoquinoline-1-carboxylate ligands,two bridging linear azide anions and two uncoordinated half-occupied water molecules.The 3-D supramolecular network results from the multiple hydrogen bonds andπ-πstacking interactions among three types of ligands.More importantly,its thermal stability,luminescent properties and magnetic properties have also been studied in detail.

Multi-color luminescence in Eu^3＋/Tb^3＋ co-doped ZnAl amorphous materials and their annealed samples

Multi-color luminescence basing on amorphous Eu^3＋/Tb^3＋ co-doped Zn-A1 hydroxides and their annealed samples were studied in detail. Results suggest that excellent red emissions due to E^u3＋ and green emissions attributed to Tb^3＋ appear under the excitation of favorable wavelength for all the as- prepared amorphous samples. Moreover, the emission intensity depends on the Eu^3＋/Tb^3＋ molar ratio. The samples annealed at 300, 500, and 700 ℃ still exhibit amorphous state, and multi-color lumi- nescence kept in the samples annealed at 300 ℃, while luminescence quenched for the samples annealed at 500 and 700 ℃. However, a broad emission ranging from 450 to 650 nm occurs in some samples annealed at 900 ℃. Further, the fluorescence decay and lifetimes for the as-prepared samples and the samples annealed at 300℃ were investigated. It is found that all the decay curves of emissions due to Tb^3＋ and Eu^3＋ present characteristic double exponential function despite their different lifetimes. The present work may be a good example for developing new multi-color even white light emitting materials.