bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photochemistry in Phototropin, a Blue Light Sensor Protein in Plants
Authors: Iwata Tatsuya , Kandori Hideki 
Published: May 2015

AbstractPhototropin (phot) is a blue‐light receptor in plants. The protein molecule has two FMN (Flavin MonoNucleotide) binding domains named LOV (Light‐, Oxygen‐, and Voltage‐sensing), which is a subset of the PAS (Per‐Arnt‐Sim) superfamily. Illumination of the phot‐LOV domains produces a covalent C(4a) flavin‐cysteinyl adduct (S390 intermediate) via a triplet‐excited state, which reverts to the original state in the dark. Chemical structure of the S‐H group of the reactive cysteine is important for the adduct formation, and several models have been proposed for efficient reaction. By means of Fourier‐transform infrared (FTIR) spectroscopy of the LOV2 domain of Adiantum phytochrome3 (phy3‐LOV2), a fusion protein of phot containing the phytochrome chromophoric domain, we have studied protonation state of the reactive cysteine (Cys966). Although it was proposed that the cysteine is deprotonated in LOV domains, we observed an S‐H stretch at ˜2570 cm−1. Since phy3‐LOV2 possesses only one cysteine at position 966, this observation clearly indicates that Cys966 is protonated. While transfer reaction of proton, hydrogen, or electron has been proposed from the cysteine in the triplet‐excited state, we also detected the S‐H stretch at 2537 cm−1 in the triplet‐excited state of phy3‐LOV2. This excludes the possibility of proton and hydrogen transfer reactions. These frequencies imply that the S‐H group is free from hydrogen bond in the unphotolyzed state, while it forms a strong hydrogen bond in the triplet‐excited state. We infer the hydrogen‐bonding acceptor to be the N(5) atom of FMN, and such strong interaction presumably drives adduct formation in a microsecond timescale.
Enhanced Energy Transfer Efficiency in Star‐Shaped Light‐Harvesting Block Copolymers Prepared by RAFT Polymerization
Authors: Chen Ming , Ghiggino Kenneth P. , Thang San H. , Wilson Gerard J. 
Published: May 2015

AbstractReversible addition‐fragmentation chain transfer (RAFT) polymerization has been used to synthesize a star‐shaped light‐harvesting polymer comprising six diblock copolymer arms of styryl coumarin (St‐Coumarin) and methyl acrylate (MA) surrounding a ruthenium (II) trisbipyridyl energy trap core. The efficiency of excitation energy transfer from the styryl coumarin units to the Ru(II) core is increased to 90% compared to 60% for the analogous star polymer without MA blocks. The enhanced excitation energy transfer efficiency arises from the role of the MA blocks in diminishing the competitive quenching of photoexcited St‐coumarin chromophores by dithiobenzoyl polymer end groups present from the RAFT polymerization procedure.
Theoretical Studies on Photophysical Properties and Mechanism of Phosphorescence in [fac‐Ir(2‐phenylpyridine)3]
Authors: Nozaki Koichi 
Published: May 2015

AbstractThe photophysical properties of [fac‐Ir(ppy)3] have been studied using time‐dependent density functional theory with one‐center spin‐orbit coupling approximation. The phosphorescent state of [fac‐Ir(ppy)3] was characterized by a mixture of 40%3MLCT and 58% intra‐ and inter‐ligand3ππ*with charge distribution being partially localized to a single ligand. Zero‐field splittings and oscillator strengths calculated for the sublevels of the lowest triplet state were in agreement with the observed values. The spin components in the sublevels and the mechanism of phosphorescence were well rationalized using a localized model for a hypothetical M‐LL unit withC2vsymmetry similarly to the cases for [Ru(bpy)3]2+or [Os(bpy)3]2+. Furthermore, it was revealed that the excited states were characterized by both high density‐of‐state (approximately 70 states per eV) and considerable mixing between singlet and triplet states due to strong spin‐orbit coupling.
Formation of Trititanate Nanotubes by Non‐Hydrothermal Methods: Optical Properties and Surface‐Exciton Dynamics Studied by Photoluminescence Spectroscopy
Authors: Jang Joon Hee , Jeon Ki Seok , Park Tae Sook , Lee Ki Whan , Yoon Minjoong 
Published: May 2015

AbstractTrititanate (H2Ti3O7) nanotubes were prepared by a non‐hydrothermal digestion of TiO(OH)2 solution with 5 M NaOH, and their optical properties and exciton dynamics were studied by using steady‐state and time‐resolved photoluminescence (PL) spectroscopy. Based on TEM, AFM and XRD measurements, the tubular structure was identified to be the same as that of trititanate crystalline multi‐walled scroll nanotubes prepared hydrothermally, which has intershell d‐spacing of 0.79 nm with inner diameters of 5 nm and the lengths of several tens of nanometers. The UV‐absorption spectrum of trititanate nanotubes showed weak surface‐state absorption at 425 nm as well as the absorption maximum band around 350 nm with onset energy 3.03 eV corresponding to the indirect band gap energy. The steady‐state PL spectra of the trititanate nanotubes showed a band‐edge emission band around 360 nm as well as a broad surface emission band originating from widely dispersed surface‐state energy levels (2.84, 2.65, 2.41 2.21 2.03 eV), exhibiting higher relative intensity ratio of the band‐edge emission to the surface emission as compared to that of TiO2 nanoparticles. These results with PL excitation spectra indicate that the density of the surface states was found to be higher in the nanotubes than in TiO2 nanoparticles. The PL decay profiles were measured by using the time correlated single photon counting system (TCSPC) adopting fs‐Ti‐Sappire laser at 350 nm, and they were analyzed to fit a tri‐exponential equation. The decay times depend on monitoring emission wavelength, and at least four different decay time components (˜28 ps, ˜70 ps, ˜700 ps and ˜4 ns) were resolved, implying the existence of charge‐carriers trapping surface states with different energy levels. The two longer decay times are attributed to the deep‐trap surface states of trititanate nanotubes, which are much longer than those of TiO2 nanoparticles. These results suggest that the nonradiative route to the surface excitons recombination is more dominant in trititanate nanotubes than in titania nanoparticles because of strong coupling of excitons wave functions with lattice phonons.
Förster Energy Transfer in Thin Films of Conjugated Polymers and in Solution
Authors: Mukherjee Arnab , Bagchi Biman 
Published: May 2015

AbstractFluorescence resonance energy transfer (FRET) is routinely used to study equilibrium and dynamical properties of polymers and biopolymers in the condensed phases. It is now being widely used in conjunction with single molecule spectroscopy where one usually employs the Förster expression which predicts (1/R6) distance dependence of the energy transfer rate. However, critical analysis shows that this expression can be of rather limited validity in many cases. We demonstrate this by explicitly considering a donor‐acceptor system, polyfluorene (PF6)‐tetraphenylporphyrin (TPP), where their sizes are comparable to the distance separating them. In such cases, one may expect much weaker distance (as 1/R2 or even weaker) dependence. We also discuss recent application of FRET to study biopolymer conformational dynamics. We show that the well‐known Wilemski‐Fixman theory needs to be generalized to treat FRET at short separations. The utility of FRET in studying protein folding is also discussed.
Solvation Dynamics in Biological Systems and Organized Assemblies
Authors: Sen Pratik , Pal Subrata , Bhattacharyya Kankan , Bagchi Biman 
Published: May 2015

AbstractSolvation dynamics of a polar probe in many biological systems and organized assemblies displays a surprising ultraslow component. The origin of this anomalous ultraslow component is investigated using experiments, theory and computer simulations. We first summarize some recent experimental results on solvation dynamics, e.g., temperature dependence, site dependence at active site of an enzyme and red edge excitation shift (REES). Then we propose two new theoretical models to explain the ultraslow component. The first one involves the motion of the ‘buried water’ molecules (both translation and rotation) accompanied by cooperative relaxation (‘local melting’) of several surfactant chains. An estimate of the time is obtained by using an effective Rouse chain model of chain dynamics, coupled with a mean first passage time calculation. The second explanation invokes self‐diffusion of the (di)polar probe (created by optical excitation) itself from a less polar to a more polar region. This may also involve cooperative motion of the surfactant chains in the hydrophobic core, if the probe has a sizeable distribution inside the core prior to excitation. It may also involve escape of the probe to the bulk from the surface of the self‐assembly. The second mechanism should result in the narrowing of the full width of the emission spectrum with time, which has indeed been observed in recent experiments. It is argued that both the two mechanisms may give rise to an ultraslow time constant and may be applicable to different experimental situations. The effectiveness of solvation as a dynamical probe in such complex systems has been discussed. Finally, we give a brief overview of recent results on computer simulations on dynamics of water molecules around a protein and a micelle.
Solvothermal Synthesis of Self‐Assembled Free‐Based Porphyrin Wires
Authors: Li Lu‐Lin , Chuang Hui‐Ju , Lin Kuan‐Jiuh 
Published: May 2015

AbstractA family of well‐defined prophyrin wires, 5,10,15,20‐tetrakis(4‐N‐ethylpyridyl)porphyrin salts [H2TEPyP4+·A] (A = 2CdI42− 1; 6I− 2; 4I− 3), has been synthesized by hydrothermal methods and was structurally characterized by X‐ray single‐crystal diffraction. Controlling the packing of π‐π stacking backbones was achieved by means of adjusting the counterbalanced anions: tetragonal packing for 1 and 2; hexagonal‐like for 3. The optical properties related to the packing structures were studied by solid‐state diffuse reflectance spectra. The blue‐shift of Soret band demonstrated the H‐aggregate form in the porphyrin wires.
Photoinduced Electron Transfer Research to Build Model Compounds of Artificial Photosynthesis and Solar Energy Conversion
Authors: Ganguly T. , Pal S. K. 
Published: May 2015

AbstractIn this article various novel synthesized dyads and triad systems containing organic based electron donor and acceptor compounds linked together by flexible and rigid spacers have been described which undergo very fast (˜ ps) charge separation reactions and relatively slow energy destructive charge recombination. Various techniques have been discussed to enhance the survival duration of the charge‐separated products, resulted from photoinduced electron transfer reactions, by retarding the energy wasting charge recombination process. It has been hinted that these systems should form the basis of future artificial photosynthetic and solar energy conversion devices.
Room Temperature Ionic Liquids as Media for Photophysical Studies
Authors: Mandal Prasun K. , Paul Aniruddha , Samanta Anunay 
Published: May 2015

AbstractIn this article, we first present a brief introduction on room temperature ionic liquids based on substituted imidazolium salts that have been the focus of extensive studies in recent years. Subsequently, we summarize some of the photophysical studies made in these ionic liquids. Finally, we discuss the suitability of the imidazolium ionic liquids in optical studies taking into consideration their absorption and fluorescence behavior.
A New Approach of Flow Graph Theory Applied in Physical Chemistry
Authors: Socol Marius , Baldea Ioan 
Published: May 2015

AbstractAn alternative method for solving homogenous and non‐homogenous differential equation systems used in chemical kinetics and pharmacokinetics on the basis of flow graph principles has been proposed. The classical method of solving these systems with flow graphs involves the employment of Laplace transform before depicting a flow graph and the inverse Laplace transform after using Mason's rules. A short description of flow graph algebra has been presented. One model very often encountered in pharmacokinetics was solved by both flow graph methods in order to make a comparison. Our proposed method is simpler and more direct, eliminating the Laplace transforms. The calculus is made directly on the base of the flow graph representing the image of reaction scheme (pharmacokinetic model).
Cyclohexene Hydroconversion Using Monometallic and Bimetallic Catalysts Supported on γ‐Alumina
Authors: Aboul‐Gheit Ahmed K. , Abdel‐Hamid Sohair M. , Aboul‐Fotouh Sameh M. , Aboul‐Gheit Noha A. K. 
Published: May 2015

AbstractThe hydroconversion of cyclohexene (CHE) using monometallic catalysts containing 0.35wt% of Pt, Pd, Ir or Re on a γ‐alumina support, as well as bimetallic catalysts containing combinations of 0.35wt% Pt with 0.35wt% of either Pd, Ir or Re on γ‐alumina, were investigated in a plug flow‐type fixed‐bed reactor. The Cyclohexene (CHE) feed was injected continuously with a rate of 8.33 × 10−3mole h−1 on 0.2 g of catalyst using a simultaneous hydrogen gas flow of 20 cm3 min−1 throughout a broad reaction temperature range of 50–400 °C. The dispersion of the metals in the catalysts was determined via H2 or CO chemisorption. The activities of the monometallic catalysts were found to be in the order: Pd > Pt > Ir > Re, whereas those of the bimetallic catalysts were in the order: PtPd > PtIr > PtRe.Cyclohexene hydrogenation and dehydrogenation reactions using the current mono‐ and bimetallic catalysts were kinetically investigated applying the absolute reaction rate theory, whereby reaction rate constant, activation energy, enthalpy and entropy of activation were computed to explain surface variations on these catalysts.
The Adsorption, Thermal Desorption and Photochemistry of Methyl Iodide on an Ag‐Covered TiO2(110) Surface
Authors: Su Chaochin , Chen Chih‐Chieng , Tsai Chih‐Song , Lin Jong‐Liang , Lin Jiing‐Chyuan 
Published: May 2015

AbstractThe thermal reactions and photochemistry of monolayer methyl iodide (CH3I) on a silver covered TiO2(110) surface have been studied using combinative techniques of temperature programmed desorption (TPD) and x‐ray photoelectron spectroscopy (XPS). About ˜ 60% of CH3I at monolayer coverage on Ag/TiO2(110) dissociates between 130 and 200 K yield adsorbed CH3 and I, with the rest desorbing molecularly at a peak temperature of 200 K in a TPD study. Photochemistry of CH3I on Ag/TiO2(110) is wavelength dependent. Irradiation of monolayer CH3I by 404 nm photon causes C‐I bond dissociation and CH3 desorption. Upon 290 nm, UV irradiation, the depletion of CH3I(a) is dominated by photodesorption of molecular CH3I.
Intermolecular Se···I Interactions Identified in Cu11(μ9‐Se)(μ3‐I)3[Se2P(OEt)2]6 Form a One Dimensional Polymeric Chain
Authors: Hunga Chiu‐Mine , Chu Yi‐Hua , Santra Bidyut K. , Liaw Ben‐Jie , Wang Ju‐Chun , Liu C. W. 
Published: May 2015

AbstractThe undecanuclear copper cluster Cu11(μ9‐Se)(μ3‐I)3[Se2P(OEt)2]6 1, has been isolated along with Cu8(μ8‐Se)[Se2P(OEt)2]6 2, from the reaction of NH4Se2P(OEt)2, Cu(CH3CN)4PF6, and Bu4NI in a molar ratio of 3:2:2 in diethyl ether. The molecular formulation of 1 was confirmed by elemental analysis, positive FAB mass spectrometry, multinuclear NMR (1H, 31P, and 77Se), and X‐ray diffraction. In cluster 1 eleven copper atoms adopt the geometry of a 3,3,4,4,4‐pentacapped trigonal prism with a selenium atom in the center. The coordination geometry for the central, nonacoordinated selenium atom is tricapped trigonal prismatic. In addition, the central core Cu11Se is further stabilized by three iodides and six dsep ligands. Besides, weak inter‐molecular Se···I interactions (3.949–3.972 Å) are uncovered and form a one dimensional polymeric chain.
Total Solubility Determination of Mixtures Containing Ampicillin Anhydrate and Ampicillin Trihydrate
Authors: Liu Chen‐Lun , Chang Tian‐Chan , Wu Shu‐Min , Chiang Huey‐Jenn 
Published: May 2015

AbstractThe dissolved concentrations of ampicillin anhydrate, ampicillin trihydrate, and their mixtures were experimentally determined. For 100% ampicillin anhydrate and 100% ampicillin trihydrate cases, the dissolved concentration (mg/mL) was equal to the total amount of 100% ampicillin anhydrate and 100% ampicillin trihydrate in 1 mL solution up to the solubility (10.8 mg/mL) of 100% ampicillin anhydrate and the solubility (5.4 mg/mL) of 100% ampicillin trihydrate. For an ampicillin anhydrate to ampicillin trihydrate mixture ratio of 75:25, the relationship between the dissolved concentration and the total amount of the mixture in 1 mL solution was the same as the 100% ampicillin anhydrate case. As for the ampicillin anhydrate to ampicillin trihydrate mixture ratios of 50:50 and 25:75, the total solubility of 10.8 mg/mL could be reached at greater amounts of the mixtures. A model of diffusion‐controlled dissolution rate mechanism with two experimental solubilities, 10.8 mg/mL for ampicillin anhydrate and 5.4 mg/mL for ampicillin trihydrate, was used to successfully interpret the solubility data.
Flow Injection Analysis of Ascorbyl Glucoside in Cosmetics by a Disposable Printed‐Circuit Board Waste Modified Electrode
Authors: Shih Ying , Zen Jyh‐Myng 
Published: May 2015

AbstractAscorbyl glucoside, i.e., ascorbic acid 2‐glucoside (AA‐2G), is anew type of stable vitamin C derived compound used in many cosmetic skin‐lightening formulations, but rarely studied in the literature. In this study, a screen printed electrode modified with copper‐enriched printed circuit‐board waste (designated as CuPCB/SPE) was applied to study the electrochemical characteristics of AA‐2G. Cyclic voltammogram of the CuPCB/SPE showed an electrocatalytic oxidative feature at ˜0.6 V vs. Ag/AgCl in 0.15 M NaOH solution. Flow injection analysis coupled with the CuPCB/SPE was further developed for sensitive AA‐2G determination. The calibration plot was linear in the window of 2.5–160 ppm with slope and regression coefficient of 0.0169 μA/ppm and 0.9971, respectively. The detection limit (S/N = 3) was 0.247 ppm. Real sample analysis was demonstrated for different skin‐lightening cosmetic products with appreciable results.
Synthesis of 2‐Phenylthiazoles from α‐Tosyloxyketones and Thiobenzamide in [Bmim][PF6] Ionic Liquid at Ambient Temperature
Authors: Hou Rei‐Sheu , Wanga Huey‐Min , Tsai Hsing‐Hui , Chen Ling‐Ching 
Published: May 2015

AbstractThe room temperature ionic liquid, 1‐n‐butyl‐3‐methylimidazolium hexafluorophosphate [bmim][PF6] is used as a ‘green’ recyclable alternative to classical molecular solvents for the cyclocondensation of α‐tosyloxyketones with thiobenzamide to prepare 2‐phenylthiazoles in good yields.
High Resolution NMR Spectroscopic Study of Complexation of Hydroxyzine Hydrochloride with β‐Cyclodextrin in Aqueous Solution
Authors: Ali Syed Mashhood , Maheshwari Arti , Upadhyay Santosh Kumar , Nam Kye Chun 
Published: May 2015

AbstractHydroxyzine hydrochloride forms two 1:1 inclusion complexes with β‐cyclodextrin in aqueous solution as confirmed by the 1H NMR titration and ROESY studies. One complex is formed by the deep penetration of the chlorophenyl ring from the wider rim side, while the mode of entry of the phenyl ring into the β‐CD cavity is not clear. The stoichiometry and overall association constant of the complexes have been determined by the treatment of 1H NMR shift data. Some chiral discrimination by the host between the two enantiomers of hydroxyzine hydrochloride is also indicated.
Synthesis and Reactions of Some New Pyrrolylfuro[2,3‐d]Pyrimidines and Pyrrolopyrazinofuropyrimidines
Authors: Abdel‐Mohsen SH. A. , Abdel‐Hafez SH. H. , Geies A. A. 
Published: May 2015

Abstract5‐Amino‐4‐methyl‐2‐phenyl‐6‐substitutedfuro[2,3‐d]pyrimidines (2a‐c) were reacted with 2,5‐dimethoxytetrahydrfuran to afford the pyrrolyl derivatives 3a‐c. Compound 3a was chosen as intermediate for the synthesis of poly fused heterocycles incorporated furopyrimidines moiety 4–11. Some of the synthesized compounds were screened for their antibacterial and antifungal activities.
Volumetric Properties for the Electrolyte (NaCl, NaBr and NaI) Monosaccharide (D‐Mannose and D‐Ribose)‐Water Systems at 298.15 K
Authors: Zhuo Ke‐Lei , Zhao Yang , Yang Li‐Xia , Liu Qian , Wang Jian‐Ji 
Published: May 2015

AbstractDensities have been measured for the electrolyte (NaCl, NaBr and NaI)‐monosaccharide (D‐mannose and D‐ribose)‐water solutions at 298.15 K. These data have been used to calculate the apparent molar volumes of the saccharides (VΦ,S) and electrolytes (VΦ,E) in the studied solutions. Infinite dilution apparent molar volumes, VΦ,S0 and VΦ,E0, have been evaluated, together with the standard transfer volumes of the saccharides (ΔtVS0) from water to aqueous electrolyte solutions and those of the electrolytes (ΔtVE0) from water to aqueous saccharide solutions. It was shown that both the ΔtVS0 and ΔtVE0 values are positive and increase with increasing molalities of sodium halides and saccharides, respectively. Overall, the ΔtVS0 and ΔtVE0 values have the order of NaCl > NaBr > NaI except for NaI‐ribose and NaI‐ribose. Volumetric interaction parameters for the electrolyte‐monosaccharide pairs in water were obtained and interpreted by the stereochemistry of the monosaccharide molecules and the structural interaction model.
Studies on the Spectral Behavior between Protein with Poniacyl Carmine 2B and its Analytical Application
Authors: Wei Qin , Li Yan , Duan Cai‐Hong , Ma Hong‐Min , Du Bin 
Published: May 2015

AbstractIn this paper, the spectral behavior of protein and Poniacyl Carmine 2B (PC 2B) has been studied by spectrophotometric method. The conditional constants, apparent combination constant K and maximum binding number n, were used to express the combination ability of the reactions between PC 2B and protein under a set of given conditions. The Sandell index s was used to express the sensitivity of the determination of protein. The factors, acidity, PC 2B concentration and the ionic strength, were discussed by the change of apparent combination constant and maximum binding number. It was found that acidity of the solution, PC 2B concentration and ionic strength had a significant effect on the sensitivity of the assay of protein. Under the optimal conditions, the apparent combination constant K and the maximum binding number n were 2.36 × 106 L mol−1 and 95, respectively. With further investigation, it was found that the Scatchard model was suitable in treating the data obtained in the experiments. In the buffer medium of HCl‐KCl at 1.87, the addition of protein made the maximum absorption of the system move from 527 nm to 513 nm. Its apparent molar absorptivity is 4.46 × 105 Lmol−1 cm−1 at 513 nm. Beer's law is obeyed in the range of 0 ˜ 55 μg mL−1. The system developed in this paper has been used for the determination of protein in milk powder successfully.
A Convenient Oxidation of 5‐Substituted Pyrazol‐3(2H)‐Ones Into Methyl 2‐Alkynoates Using Poly[4‐(Diacetoxyiodo)Styrene]
Authors: Huang Zhen‐Zhong , Sheng Shou‐Ri , Liu Xiao‐Ling , Lin Shu‐Ying , Huang Ren‐Sheng 
Published: May 2015

AbstractAn operationally simple oxidation of 5‐substituted pyrazol‐3(2H)‐ones to the corresponding methyl‐2‐alkynoates in good yields with a mediated poly[4‐(diacetoxyiodo)styrene] system in methanol and acetonitrile at room temperature was carried out. The polymeric reagent can be regenerated and reused as an environmentally benign reagent.