Chemical Physics Letters (v.479, #1-3)

Contents (iii-xii).

Structure in confined colloid suspensions by Stuart A. Rice (1-13).
Distribution of a third particle about two that are separated by two diameters in a q2D colloid suspension.The study of confined condensed matter is motivated by the observation that when the range of molecular interaction and the length scale associated with position correlation in a system are similar to the length scale of confinement, that system can support structures and have transport properties that differ from those found in the bulk. This Letter is a selective overview of information that has been obtained about the nature of phase transitions from studies of confined quasi-two-dimensional colloid suspensions, with attention paid to the roles of the colloid–colloid interaction and the extent of deviation from an idealized geometry of confinement, e.g. whether and/or how phase transitions in quasi-one-dimensional and quasi-two-dimensional systems differ from those in a two-dimensional system or a three-dimensional system.

Nuclear-spin-induced optical Cotton–Mouton effect in fluids by Tong-tong Lu; Ming He; Dong-ming Chen; Tian-jing He; Fan-chen Liu (14-19).
This effect can give information on molecular structures in fluids via nuclear spin–spin coupling tensors.Relation between the optical detection of NMR signals by the Faraday and Cotton–Mouton effects in fluids and nuclear spin–spin coupling tensors is theoretically explored. An expression is derived for nuclear-spin-induced optical Cotton–Mouton (NSIOC-M) effect from molecules with the prepolarized nuclear magnetic moments. That contains two parts. The temperature independent part is related to hypermagnetizability due to the nuclear magnetic moments. The temperature dependent part is proportional to product between nuclear spin–spin coupling tensors and anisotropy of molecular polarizabilities. NSIOC-M effect can give information on molecular structures in fluids, such as bond lengths and angles. Order of magnitude of the new effect are estimated.

Atmospheric HFEs degradation in the gas phase: Reaction of HFE-7500 with Cl atoms at low temperatures by Yolanda Díaz-de-Mera; Alfonso Aranda; Iván Bravo; Elena Moreno; Ernesto Martínez; Ana Rodríguez (20-24).
Reaction rate of HFE-7500 with Cl atoms can drastically be modified by the temperature. This effect may be important in the troposphere, where temperature drops with altitude.The discharge-flow technique was used to determine the temperature dependence of the rate constant of the reaction of HFE-7500 (n-C3F7CF(OC2H5)CF(CF3)2) with Cl atoms at 1 Torr pressure. The study has been carried out from 253 to 343 K to approach to the tropospheric temperature profile. At room temperature the measured rate constant is k 1  = (2.2 ± 0.6) × 10−12  cm3  molecule−1  s−1 (error is 2σ  + 15%). The Arrhenius expression derived from our results is k 1  = (1.1 ± 0.6) × 10−10exp[(−1190 ± 270)/T] cm3  molecule−1  s−1 (errors are 2σ  + 15%). The reaction proceeds through hydrogen abstraction with a measured yield of HCl of 0.98 ± 0.24 (error is 2σ  + 15%). The atmospheric implications of this reaction have been evaluated and its significance has been evidenced.

The kinetics of the reactions of Cl atoms with ethyl vinyl ketone, vinyl propionate and ethyl acrylate were investigated for the first time at 298 K and atmospheric pressure using the GC–FID technique and the relative rate method. Structure activity relationships were developed for the reactions of Cl wide a wide range of unsaturated compounds and atmospheric implications are assessed.The kinetics of the reactions of Cl atoms with three unsaturated carbonyl compounds at 298 K and atmospheric pressure were investigated for the first time using the GC–FID technique. Rate coefficients (in cm3  molecule−1  s−1) of k 1(Cl + CH2 =CHC(O)CH2CH3) = (2.91 ± 1.10) × 10−10, k 2(Cl + CH2 =CHOC(O)CH2CH3) = (2.06 ± 0.36) × 10−10 and k 3(Cl + CH2 =CHC(O)OCH2CH3) = (2.53 ± 0.46) × 10−10 were obtained using the relative rate method with different references. Structure activity relationships (SARs) were developed for the reactions of Cl with a wide range of unsaturated compounds. On the basis of our kinetic measurements, tropospheric lifetimes of the studied unsaturated compounds are estimated.

Collisions between Rydberg atoms and electron-attaching species can lead to formation of heavy-Rydberg ion-pair states with extremely large principal and angular momentum quantum numbers, a consequence of their large reduced mass.The formation of K+⋯Cl heavy-Rydberg ion-pair states through dissociative electron transfer in K(np)/CCl4, n  = 16–50, collisions is examined, the product ion-pair states being detected directly through electric field-induced dissociation. The results are analyzed with the aid of a Monte Carlo collision code that models both initial Rydberg electron capture and the subsequent evolution of the ion pairs. The data demonstrate the production of long-lived (τ  ≫ 10 μs) high-angular-momentum K+⋯Cl ion-pair states and suggest that Rydberg atom collisions can generate a wide variety of heavy-Rydberg species facilitating study of their physical and chemical properties.

CCSD(T)/6-311++G(df, pd)//MP2(full)/6-311++G(d, p) minimum energy path (MEP) for the reaction of OH radicals with CF3CF=CH2.An extensive quantum chemical study of the potential energy surface (PES) for the possible pathways of the reaction of OH + CF3CF=CH2 is reported. Critical points are optimized at the MP2(full)/6-311++G(d, p) level of theory, combined with single-point energy calculations at the CCSD(T)/6-311++G(d, p) level. The calculated results demonstrate that energetically accessible reaction pathway is the formation of CH3  + CF3C(O)F via the subsequent rearrangement and dissociation reaction starting from the adduct CF3CF(OH)CH2 (IM2). The theoretical rate constants are also calculated for the main reaction pathways using the transition state theory. The predicted values are in good agreement with the experimental results.

Effects of hydrogen bonding on the ring breathing mode of pyridine in pyridine/chloroform and pyridine/bromoform systems by Haiyan Fan; C. Diane Moliva A.; Jeffrey K. Eliason; Jason L. Olson; Daniel D. Green; M.W. Gealy; Darin J. Ulness (43-46).
The ring breathing mode of pyridine acts as a sensitive marker for hydrogen bonding. This work investigates the weak hydrogen bonding between pyridine and chloroform or bromoform.Hydrogen bonding between pyridine and chloroform as well as pyridine and bromoform is studied using noisy light-based coherent anti-Stokes Raman scattering (I(2)CARS). A blue-shift in the ring breathing mode of pyridine is observed when a hydrogen bond complex is formed between the nitrogen on pyridine and the hydrogen from the donor molecule. The formation of the hydrogen bond between haloforms and pyridine is very weak and does not result in an independent peak. Nonetheless, data analysis allows for identification of a small blue-shift of the hydrogen bonded complex.

Nematic liquid crystal undergoing planar Couette flow with director perpendicular to the shear plane.The three Miesowicz viscosities of a liquid crystal model system consisting of the Gay–Berne fluid have been obtained by shear flow simulations. The viscosities along an isochore have been followed starting in the nematic phase at high temperatures across the nematic–smectic A phase transition down to low temperatures in the smectic A phase. The relative magnitudes of the viscosities as a function of the structure of the liquid crystal are discussed. The viscosities obtained by the shear flow simulations agree very well with those obtained by Green–Kubo relations in a previous work.

Two-photon absorption of perylene derivatives: Interpreting the spectral structure by E. Piovesan; D.L. Silva; L. De Boni; F.E.G. Guimaraes; L. Misoguti; R. Zaleśny; W. Bartkowiak; C.R. Mendonca (52-55).
Using the white-light continuum Z-scan we investigate a well defined structure in the two-photon absorption spectrum of perylene derivatives.This work investigates the two-photon absorption spectrum of perylene tetracarboxylic derivatives using the white-light continuum Z-scan technique. Perylene derivatives present relatively high two-photon absorption cross-section, which makes them attractive for applications in photonics. Because of the spectral resolution of the white-light continuum Z-scan, we were able to observe a well defined structure in the two-photon absorption spectrum, composed by two distinct peaks. These peaks, as well as the resonant enhancement of the nonlinearity, were modeled using the sum-over-states approach considering a four-level energy diagram with two final two-photon states. The existence of such states was confirmed using the response function formalism within the DFT framework.

The hydration entropy, at 25 °C and 1 atm, of neutral solutes is largely insensitive to the polar nature of the molecule, and is well reproduced by the entropy change upon cavity creation, as calculated by the classic scaled particle theory.At room temperature and atmospheric pressure, the magnitude of the hydration entropy of neutral solutes increases with the molecular volume according to a trend that is largely insensitive to the polar nature of the solute molecule. This general trend is well reproduced by the entropy change upon cavity creation in water as calculated by means of classic scaled particle theory. In contrast, the magnitude of the hydration entropy of the 20 alkali halides decreases on increasing the size of the constituent ions, demonstrating that the strength of charge–water dipole interactions plays the dominant role.

Vapor–liquid phase equilibria of water modelled by a Kim–Gordon potential by Katie A. Maerzke; Matthew J. McGrath; I.-F. William Kuo; Gloria Tabacchi; J. Ilja Siepmann; Christopher J. Mundy (60-64).
A frozen-electron-density model allows for seamless coupling to Kohn–Sham density functional theory, but exhibits limited transferability to other state points.Gibbs ensemble Monte Carlo simulations were carried out to investigate the properties of a frozen-electron-density (or Kim–Gordon, KG) model of water along the vapor–liquid coexistence curve. Because of its theoretical basis, such a KG model provides for seamless coupling to Kohn–Sham density functional theory in mixed quantum mechanics/molecular mechanics implementations. The Gibbs ensemble simulations indicate limited transferability of a KG model to other state points. Specifically, a KG model that was parameterized by Barker and Sprik to the properties of liquid water at 300 K, yields saturated vapor pressures and a critical temperature that are significantly under- and overestimated, respectively.

Laser spectroscopic investigation of lithium doping effect on luminescence enhancement in YVO4:Eu3+ thin films by Kyoung Hyuk Jang; Eun Sik Kim; Liang Shi; Jung Hyun Jeong; Hyo Jin Seo (65-69).
Time-resolved emission spectra of Li-doped and Li-undoped YVO4:Eu3+ thin films under the near-band-edge excitation at 355 nm.YVO4:Eu3+ thin films doped with Li ions were grown by the pulsed laser deposition method and their luminescence properties are investigated by the time-resolved laser-excitation spectroscopy. The emission spectra originating in the self-trapped exciton and near-band-edge of YVO4 host lattice are separated by the method of time-resolved spectroscopy. The emission arising from near-band-edge is significantly reduced by Li substitution in the YVO4:Eu3+ lattice leading to luminescence enhancement.

Magnetic field effect in two time scale has been observed for photo-induced geminate singlet radical pairs in SDS micelle.We have studied the magnetic field effects (MFEs) on photo-generated various geminate phenyl–pyrilium/biphenyl radical pair (PP/BP+• ) of variable singlet/triplet spin-correlations within SDS micelle. When RPs are produced largely with singlet spin-correlation, the MFEs have been observed in two different time domains. It consists of both the initial (t  = 0) decrease of radical yield with field, considering nanosecond phenomenon, and comparatively slow microsecond MFE. However, the RPs of relatively lower singlet spin-correlation shows only slow μs behavior, which may indicate that only singlet spin-state is responsible for exhibiting initial stage MFEs. A kinetic scheme, based on Pedersen’s ‘super-cage model’ for two-stage RP reaction in micelle, has been proposed for analysis.

Ten square micron AFM images of 120 nm-thick perylene films on SiO x /Si(1 0 0), grown at T sub  = 300 K and a deposition rate of 11.6 nm/min. The grey scale corresponds to the first derivative to better represent the grain structure. The z-axis is expanded in comparison to the x- and y-axes. It is clearly visible that the grain size is relevantly larger in comparison with the preparation at lower temperature and lower deposition rates and the film growth shows a different behavior.Thin films of perylene on SiO x /Si(1 0 0) and SiO2/Si(1 0 0) substrates have been studied by X-ray photoelectron spectroscopy and atomic force microscopy. These investigations reveal that structure, morphology, and growth modes depend on the preparation parameters. By varying the deposition rate between 0.8 and 16 nm/min, a transition from island growth mode, with large and isolated crystallites, to a homogeneous film growth is observable.We can predict the growth of perylene on technologically relevant substrates: homogeneous smooth films at lower substrate temperature (below 200 K) and single grains, enough for single nanodevices, when the film is grown at higher substrate temperature.

Direct evidence of the dielectric confinement effect in the infrared spectra of organic liquids by Tatiana S. Perova; Igor I. Shaganov; Vasily A. Melnikov; Kevin Berwick (81-85).
Absorbance spectra of benzene infiltrated into silicon pores. Insert: schematic diagram of the conversion of liquid infiltrated into the macro-porous silicon matrix from a bulk liquid phase to a liquid under 1D dielectric confinement as a result of the drying process.In this study, the size (dielectric) confinement effect on the peak position of intra-molecular vibrations in the infrared spectra of liquid benzene, carbon disulphide and chloroform is described theoretically, and observed experimentally, for the first time. It is shown that the shift in the peak position due to the dielectric confinement effect can reach a few tenths of a wavenumber for strong vibrational bands. The results obtained confirm the applicability of the dispersive local-field approach for the description of the dielectric confinement effect for liquid media, as well as for crystalline and amorphous solids.

Silicon doping of spray-deposited Fe2O3 results in the formation of the β-Fe2O3 phase; the presence of a SnO2 interfacial layer suppresses this and favours the growth of α-Fe2O3 with a slightly preferred (1 1 0) orientation.Fe2O3 films on Si wafer and fused silica substrates have been prepared by spray pyrolysis. The influence of the Si dopant and the SnO2 interfacial layer on the crystal structure and orientation of the Fe2O3 films has been systematically studied. It is found that Si doping results in the formation of β-Fe2O3, while the SnO2 interfacial layer directs the growth of α-Fe2O3 in the [1 1 0] direction. The Raman spectrum of β-Fe2O3 is identified and the thermal stability of β-Fe2O3 was investigated. It appears that β-Fe2O3 is a metastable phase that is stabilized by the presence of the Si dopant.

Reporting high structural stability of SWNT well beyond that of sp 2 C=C bonds in graphite and carbon fullerenes.In quasi-hydrostatic conditions, single wall carbon nanotubes (SWNTs) exhibit high structural stability to ∼35 GPa, well beyond the stability of sp 2 C=C bonds in graphite, carbon fullerenes, benzene, and other hydrocarbons. The pressure-induced Raman changes of SWNT are completely reversible below 16 GPa, partially reversible between 16 and 35 GPa, and irreversible beyond 35 GPa where it turns into highly disordered graphite. We explain the high stability in terms of the pressure-induced structural modification to an interlinked configuration, which occurs reversibly under substantial sp 3 hybridization (∼20%) and, thus, increases the stability of sp 2 C=C bonds in the SWNTs.

Molecular dynamics (MD) simulations are carried out to investigate the interplay of diffusion of molecules in small single crystals and the surrounding mesopores. The results indicate that mesopores in membranes could be used to increase the overall flux through the membrane under the conditions when almost all guest molecules diffuse in the zeolite at least part of the time. This is of interest for understanding and optimization of the performance of mixed matrix membranes.Molecular transport through membranes containing zeolite crystals and slit mesopores between them was examined by molecular dynamics simulations. The feasibility of fabrication of this type of membranes was recently demonstrated in Yoon [K.B. Yoon, Acc. Chem. Res. 40 (2007) 29]. Our results indicate that mesopores could be used to increase the overall flux through membranes under the conditions when almost all guest molecules diffuse in the zeolite at least part of the time needed to cross over the membrane. Diffusion in zeolite micropores is essential for achieving selectivity in separations. The results are of interest for understanding and optimization of mixed matrix membranes.

We demonstrate the tuning of the surface plasmon resonance (SPR) band of elliptical Au0 nanoparticles (587–611 nm) by controlling the refractive index (1.8349–2.0006) of the encapsulating host matrix in a new series of nano-Au0-antimony glass (K2O–B2O3–Sb2O3) dichroic composites which are synthesized by a new single-step methodology without using any external reducing agent or additional processing step.Tuning of the surface plasmon resonance (SPR) band of Au0 (587–611 nm) has been demonstrated by controlling the refractive index (1.8349–2.0006) of the encapsulating matrix in a new series of nano-Au0-antimony glass (K2O–B2O3–Sb2O3) dichroic devitrified composites. They have been synthesized by a single-step melt-quench in situ thermochemical reduction technique without using any external reducing agent or additional processing step. Dichroic behavior is due to elliptical shape of Au0 nanoparticles having 13–18 nm size range and aspect ratio about 1.2 according to transmission electron microscopic image. X-ray and selected area electron diffractions manifest the growth of (1 1 1) and (2 0 0) crystallographic planes of Au.

Kelvin Probe Force Microscopy study on hybrid P3HT:titanium dioxide nanorod materials by Tsung-Wei Zeng; Fang-Chi Hsu; Yu-Chieh Tu; Tsung-Han Lin; Wei-Fang Su (105-108).
Surface morphology and photo-response of various hybrid P3HT:TiO2 nanorod (a) without and (b) with TiO2 nanorod surface layer are studied by KPFM.We present a Kelvin Probe Force Microscopy (KPFM) study on the topography combined with surface potential of hybrid poly(3-hexylthiophene)(P3HT):TiO2 nanorod materials in dark and under illumination. The hybrid materials with fine and coarse phase separation are displayed. The photo-induced electron accumulation on surface is pronounced under high loading TiO2 nanorod in the blend. Large surface roughness, large surface height difference and potential variation in the hybrid P3HT:TiO2 nanorod are present with high content TiO2. Additionally, the incorporating a TiO2 nanorod layer on the surface of hybrid layer to facilitate collecting the electron and blocking the hole is investigated.

Nano-sized MoS2 or WS2 particles may replace the currently used micro-size counterparts in the industrial hydrodesulfurization process of crude oil.The adsorption kinetics of n-pentane, thiophene, and benzene on WS2 nanotubes have been studied by thermal desorption spectroscopy (TDS). First evidence is obtained that these probe molecules adsorb on internal, external, and groove sites of the nanotubes. Reactive TDS experiments reveal some catalytic activity towards hydrodesulfurization of thiophene.

Probing the chemical interaction between iridium nanoparticles and ionic liquid by XPS analysis by F. Bernardi; J.D. Scholten; G.H. Fecher; J. Dupont; J. Morais (113-116).
The interaction of an imidazolium ionic liquid (EMI.EtSO4) with dispersed Ir nanoparticles has been evidenced from in situ X-ray photoelectron spectroscopy analysis. In situ X-ray photoelectron spectroscopy analysis of Ir(0) nanoparticles (1.6 ± 0.3 nm) dispersed in imidazolium ionic liquid (EMI.EtSO4) shows evidences of the effective interaction between the metallic clusters and the surrounding liquid. By monitoring the C 1s signal of the ionic liquid one observes a change of the binding energy in one of its components (C2) when in the presence of Ir nanoparticles. This result was corroborated by isotope labeling experiments.

Two-level self-assembly from nanowires to microrods based on a heterotriangulene derivative by Huaqiang Zhang; Yanqin Li; Xiangjian Wan; Yongsheng Chen (117-119).
Compound 1 could assemble into supramolecular organizations from straight nanowires to well-organized microrods through a two-level self-assembly process.Compound 1 was synthesized by a palladium-catalyzed Sonogashira cross-coupling reaction of heterotriangulene derivative 3 with three equiv. of 1-dodecyloxy-4-ethynylbenzene 2 in good yield. After the dichloromethane solution of 1 was mixed with methanol, two-level self-assembly from nanowires to microrods based on 1 was obtained and characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The driving force of the two-level self-assembly is attributed to the strong π–π stacking interactions of heterotriangulene cores and the hydrophobic interactions of alkyl chains with solvent molecules.

By using first-principles calculations, we investigate the switching mechanism of diarylethene molecules sandwiched between metallic carbon nanotubes with open and closed configurations.We report first-principles calculations of the electronic and transport properties of diarylethene molecules sandwiched between metallic armchair (5, 5) carbon nanotubes with open and closed configurations. The calculated transmission spectra of two configurations are distinctively different near the Fermi level, and their profiles can be tuned by the gate bias voltage. The on–off ratio of currents between the closed and open configurations under a gate bias voltage is predicted to be more than two orders of magnitude, which reproduces the essential features of the experimental results. Moreover, we find that the switching property of diarylethene molecular junctions is very robust to the anchoring configuration, substituent of cyclopentene, and choice of electrodes.

Ultrathin aligned ZnO nanorod arrays grown by a novel diffusive pulsed laser deposition method by Gareth M. Fuge; Tobias M.S. Holmes; Michael N.R. Ashfold (125-127).
Diffusive pulsed laser deposition is demonstrated as a novel route to forming aligned arrays of ultrathin ZnO nanorods.ZnO nanorod (NR) arrays were grown on Si at elevated temperatures using a two-stage diffusive pulsed laser deposition (DPLD) technique. A thin (∼50 nm) seed-layer was first formed by pulsed laser ablation of ZnO in O2. The sample was then turned to face away from the propagation direction of the ablation plume, and the ablation process continued. A dense array of ultrathin NRs was seen to grow from the seed-layer. These NRs are thinner (d  ∼ 10 nm), and display a ∼20-times higher aspect ratio than those grown by traditional PLD under otherwise identical process conditions.

Morphology effects of nanocrystalline CeO2 on the preferential CO oxidation in H2-rich gas over Au/CeO2 catalyst by Guangquan Yi; Zhongning Xu; Guocong Guo; Ken-ichi Tanaka; Youzhu Yuan (128-132).
A strong morphology effect of nanocrystalline CeO2 on the preferential CO oxidation in H2-rich gas over Au/CeO2 catalyst has been reported.Gold supported on CeO2 nanocrystals of rod, cubic and polyhedral shapes were used for CO preferential oxidation (CO-PROX) in H2-rich gas. The catalytic activity ranked by CeO2 nanocrystals as follows: rods > polyhedra > cubes. The results of X-ray photoelectron spectroscopy, temperature-programmed reduction/desorption and in situ Fourier transform infrared spectroscopy indicated that the surface gold species and also the adsorption/desorption properties for CO and oxygen species were closely related to the nature of exposed crystal planes of CeO2 nanocrystals. The gold catalyst on CeO2-rods with {1 0 0}/{1 1 0}-dominant surfaces showed the best CO-PROX performance.

Understanding Peierls distortion in one-dimensional infinite V-chain and V–Bz multi-decker complex by Sudipta Dutta; Tarun K. Mandal; Ayan Datta; Swapan K. Pati (133-136).
Ab initio and many body calculations suggest that the dimerization in one-dimensional linear vanadium chain almost disappears in vanadium–benzene multi-decker system.We perform first-principles calculations based on density-functional theory to study the stable structures of one-dimensional (1D) linear infinite vanadium (V) chain. The calculation shows that it prefers to dimerize according to the Peierls theorem. However, in 1D infinite neutral V–benzene (V–Bz) multi-decker complex, the dimerization almost disappears because of the screening effect of the intervening benzene rings. Additionally, we study the effect of electronic correlations on dimerization in 1D chains. Our numerical analysis reveals that, although the strong electron–electron interaction suppresses the dimerization, strong electron–phonon coupling overwhelms it to gain stability through dimerization in such systems.

Photoswitchable molecular wires: From a sexithiophene to a dithienylethene and back by Maaike T.W. Milder; Jetsuda Areephong; Ben L. Feringa; Wesley R. Browne; Jennifer L. Herek (137-139).
A molecular wire with photoswitchable end groups is photo-toggled between a sexithiophene and a dithienylethene.Photoswitchable dithienylethene groups, added to both α-ends of a sexithiophene molecular wire, switch reversibly between their open and closed forms upon irradiation. The open form has an excited state lifetime of 500 ps and is highly fluorescent, as is typical for oligothiophenes. In contrast the closed form is non-fluorescent and the excited state lifetime is a shorter by a factor of 100, reminiscent of a dithienylethene. In this system, we control the fundamental character of a molecular system through optical switching; toggling between a sexithiophene molecular wire and a dithienylethene reversibly.

Wavelength-dependent electron–phonon coupling in impurity glasses by Margus Rätsep; Mihkel Pajusalu; Arvi Freiberg (140-143).
A strong increase of the electron–phonon coupling strength on excitation wavelength was first observed for low-temperature organic glass samples.By applying an advanced hole-burning fluorescence line-narrowing technique, an unexpectedly strong (several-fold) increase of the electron–phonon coupling strength on excitation wavelength through the inhomogenously broadened absorption origin band was first observed for low-temperature organic glass samples doped with biologically relevant chlorin and chlorophyll a molecules. The dependence, which suggests a direct correlation between solvent shift and the electron–phonon coupling, demonstrates great sensitivity of the zero-phonon transitions localized on single chromophores as optical probes of the structure and dynamics of local subnanoscopic environments.

Chlorophyll catalyses the photoinduced reduction of benzoquinone.The photochemical reaction mechanisms of a supramolecular model system consisting of a truncated chlorophyll, imidazole, and benzoquinone have been explored with ab initio electronic-structure methods. The calculations indicate that a photoinduced electron-driven proton-transfer process leads to the oxidation of imidazole and reduction of the quinone. The repeated photoinduced reduction of benzoquinone is a mechanism which can lead to the decomposition of water by sunlight.

A computational ONIOM model for the description of the H-bond interactions between NU2058 analogues and CDK2 active site by Jans H. Alzate-Morales; Julio Caballero; Fernando D. Gonzalez-Nilo; Renato Contreras (149-155).
An ONIOM computational study to determine the interaction energy between different models of CDK2 active site and some purine inhibitors.The ONIOM method was applied to study the hydrogen bond interactions between some CDK2 inhibitors and various models of the active site in CDK2/CyclinA system. It was found that according with the model’s size, a good description of the molecular interactions inside the active site can be obtained. From best model, it was possible to obtain a reliable correlation between the total ONIOM energy and the biological activity reported for compounds studied. The results show that H-bond interaction energy is the principal component in this protein–ligand interaction and residues Lys89 and Asp86 are essential for great potency of compound NU6102.

The electronic structure and metal–metal interaction of [AuCl(PH3)2]Tl+ was studied. Metallophilic Au–Tl interaction was found to be mainly contributing to the short- and long-range stability in the complex.We propose that stable [AuCl(PH3)2]Tl+ can be synthesized.We studied the attraction between Au and Tl in the [AuCl(PH3)2]Tl+ complex using ab initio methodology. This is a hypothetical compound. We found that the changes around the Au–Tl equilibrium distance and in the interaction energies are sensitive to the electron correlation potential. This effect was evaluated using HF, MP2, MP4 and CCSD(T) levels. The obtained interaction energy differences in the equilibrium distance (Au–Tl) ranged from 37 to 98 kJ/mol. At long distances, the behaviour of the [AuCl(PH3)2]–Tl+ interaction may be mainly related to charge-induced dipole and dispersion terms. The charge-induced dipole term was found to be principally contributing to the stability. The dispersion interaction was smaller, but not negligible.

The positions of the grid points for evaluating the Slater-type geminal and Yukawa potential integrals.A simple, yet effective algorithm is developed for evaluating two-electron Slater-type geminal and Yukawa potential integrals over Gaussian-type orbitals (GTOs), which arise in the so-called explicitly correlated methods, on the basis of the recent work of Ten-no [S. Ten-no, Chem. Phys. Lett. 398 (2004) 56; S. Ten-no, J. Chem. Phys. 126 (2007) 014108]. Gaussian quadrature is used in analogy with the Rys quadrature method for electron repulsion integrals. The quadrature grids are obtained by the two-dimensional Chebyshev interpolation. This algorithm is especially efficient for integrals over GTOs with high angular momenta, which are present owing to the use of the resolution-of-the-identity approximation.

Harmonic peaks in 1D NMR spectra induced by radiation damping fields by Ling Peng; Shuhui Cai; Riqiang Fu; Chaohui Ye; Zhong Chen (165-170).
Harmonic peaks induced by the interaction of the radiation damping fields from two mixed solvents appear in single-pulse NMR spectra.It is found experimentally that there exist some harmonic peaks in one-dimensional NMR spectra of solution samples with two dominant solvents. Theoretical analysis indicates that such harmonic peaks result from the interaction between two radiation damping fields induced by the dominant solvents. Using a homo-nuclear decoupling pulse as a radiation damping field, a novel detection approach is proposed to investigate these harmonic peaks without interferences caused by the nonlinear amplification of the receiver. The results presented herein give a new insight into the radiation damping effects in samples with solvent mixtures (e.g. natural products) at high fields.

Erratum to ‘Electron donor solvent effects on the (hyepr)polarizabilities of a singlet diradical molecule involving a boron atom’ [Chem. Phys. Lett. 477 (2009) 309] by Kazuki Kubota; Hideaki Takahashi; Hitoshi Fukui; Sean Bonness; Kyohei Yoneda; Ryohei Kishi; Takashi Kubo; Kenji Kamada; Koji Ohta; Benoît Champagne; Edith Botek; Masayoshi Nakano (171).