absorption and phosphorescent mechanism of three Au（III） complexes, Au（2,5-F2C6H3-C^CAC）（C = C-C6H4N（C6Hs）2 [Au25FPh], Au（3,5-F2C6Ha-CACAC）（C=C-C6H4N（C6Hs）2 [Au35FPh], and Au（3,5-F2C6H3-CAC^C）（C=C-C6H4N（1H- indole）2 [Au35FID], are calculated and compared using density functional theory （DFT） and time-dependent DFT （TDDFT）. The calculated results reveal that enlarging the center CACAC ligand will result in the enhanced LMCT participation. This theoretical contribution allows design of new Au（III） complexes with higher phosphorescence efficiency.
Second-order Maller-Plesset （MP2） and density functional theory （DFT） calculations have been carried out in order to inves- tigate the structures and properties of dihydrogen-bonded CaH2...HY （Y = CH3, C2H3, C2H, CN, and NC） complexes. Our cal- culations revealed two possible structures for Call2 in CaH2..,HY complexes： linear （I） and bent （II）. The bond lengths, interac- tion energies, and strengths for H...H interactions obtained by both MP2 and B3LYP methods are quite close to each other. It was found that the interaction energy decreases with increasing electron density at the Ca-H bond critical point. At- om-in-molecule （AIM） results show that for all of Ca-H...H-Y interactions considered here, the Laplacian of the electron densi- ty at the H--.H bond critical point is positive, indicating the electrostatic nature of these Ca-H...H-Y dihydrogen bonded systems.
A variety of heteroleptic ruthenium sensitizers have been engineered and synthesized because of their higher light-harvesting efficiency and lower charge-recombination possibility than the well known homoleptic N3 dye. As such, a great deal of atten- tion has been focused on sensitizers with the general formula Ru（ancillary-ligand）（anchoring-ligand）（NCS）2, among which important examples are Ru（4,4＇-bis（5-hexylthiophen-2-yl）-2,2＇-bipyridine）（4,4＇-carboxylic acid-4＇-2,2＇-bipyridine）（NCS）2 （C101） and Ru（N-（4-butoxyphenyl）-N-2-pyridinyl-2-pyridinamine）（4,4＇-carboxylic acid-4＇-2,2＇-bipyridine）（NCS）2 （J13）. In order to simulate experimental conditions with different pH values, the photosensitizing processes of these sensitizers pos- sessing different degrees of deprotonation （2I-I, lit to OH） have been explored theoretically in this work. Their ground/excited state geometries, electronic structures and spectroscopic properties are first calculated using density functional theory （DFT） and time-dependent DFT （TDDFT）. The absorption and emission spectra of all the complexes in acetonitrile solution are also predicted at the TDDFT （B3LYP） level. The calculated results show that the ancillary ligand contributes to the molecular or- bital （MO） energy levels and absorption transitions. It is intriguing to observe that the introduction of a thiophene group into the ancillary ligand leads directly to the increased energy of the absorption transitions in the 380-450 nm region. The calcula- tions reveal that although deprotonation destabilizes the overall frontier MOs of the chromophores, it tends to exert a greater influence on the unoccupied orbitals than on the occupied orbitals. Consequently, an obvious blue shift was observed for the absorptions and emissions in going from 21-1, 1H to OH. Finally, the optimal degree of deprotonation for C101 and J13 has al- so been evaluated, which is expected to lead to further improvements in the perfo
Compression isotherm for stearic acid was obtained by means of molecular dynamic simulation and compared to experimentally measured values for the Langmuir monolayers. Compared to the previous simulation, the present simulation has provided a method to reproduce the compression of the monolayer. The result is consistent with other experimental results. By analyzing the alkyl tails, the configuration of stearic acid molecules during the compression process was studied and a uniform monolayer was obtained after compression. Stearic acid molecules were observed to form fine organized monolayer from completely random structure. Hexatic order of the arrangement has been identified for the distribution of stearic acid molecules in the monolayer. At the end of the compression, the stearic acid molecules were tightly packed in the gap of two other molecules. At last, the hydrogen bonds in the system were analyzed. The main hydrogen bonds were from stearic acid-water interaction and their intensities constantly decreased with the decreased of surface area per molecule. The weak hydrogen bond interaction between stearic acid molecules may be the reason of easy collapse.
KONG Chui-peng ZHANG Hong-xing ZHAO Zeng-xia ZHENG Qing-chuan
