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991.
Two novel species, trichloromethanesulfenyl acetate, CCl(3)SOC(O)CH(3), and trichloromethanesulfenyl trifluoroacetate, CCl(3)SOC(O)CF(3), have been generated in situ by the heterogeneous reactions between trichloromethanesulfenyl chloride, CCl(3)SCl, and corresponding silver salts, silver acetate (AgOC(O)CH(3)) and silver trifluoroacetate (AgOC(O)CF(3)), respectively. Photoelectron spectroscopy and quantum chemical calculations are performed to investigate these two molecules, together with their precursor, CCl(3)SCl. Both of these two compounds may exist in the gas phase as a mixture of gauche and trans conformations. As for the dihedral angles delta(RSOR') of the gauche conformers, 107.0 degrees and 108.5 degrees are derived by theoretical calculations (at the B3LYP/6-311+G(3df) level) for CCl(3)SOC(O)CH(3) and CCl(3)SOC(O)CF(3), respectively. The first vertical ionization energies of CCl(3)SOC(O)CH(3) and CCl(3)SOC(O)CF(3), which have been determined by photoelectron spectroscopy, are 9.67 and 10.34 eV, respectively. According to the experimental results and theoretical analysis, the first ionization energy of these two molecules both come from the ionization of the lone pair electron of S atom. 相似文献
992.
A dual laser ionization (DLI) apparatus was used to determine ionic diffusion and mobility coefficients for sodium and lithium in a stoichiometric H2/O2/Ar flame. The flame temperature was calculated using the Einstein relation. The sodium and lithium DLI temperature estimates are in agreement with each other and with temperatures measured by the line-reversal technique in similar flames. 相似文献
993.
The geometric and electronic structures of poly(9,9-dioctylfluorene) (PFO) oligomer interacting with Ca atoms were studied using M?ller-Plesset perturbation theory. A weak interaction with little charge transfer and with a relatively long Ca-C distance (about 4.0 Angstrom) was found when only one Ca atom was attached to a PFO unit. However, when two Ca atoms were adsorbed at a PFO unit, a strong interaction with a shorter Ca-C distance (about 2.67 Angstrom) took place with considerable charge transfer from the Ca atom to the PFO, resulting in significant deformation in the backbone of the PFO oligomer. In the latter case, the frontier orbitals of the PFO were modified. However, the deformed PFO and its modified frontier orbitals could be recovered when oxygen was added, which is in good agreement with experimental observation. 相似文献
994.
Fu TW Liao YH Chen CY Chang PT Wang CY Lin JL 《The journal of physical chemistry. B》2005,109(40):18921-18928
Temperature-programmed reaction/desorption, reflection-absorption infrared spectroscopy, and density functional theory calculations have been employed to investigate the adsorption and thermal reactions of ClCH2CH2OH on clean and oxygen-precovered Cu(100) surfaces. On Cu(100), ClCH2CH2OH is mainly adsorbed reversibly. The ClCH2CH2OH molecules at a submonolayer coverage can change their orientation with increasing temperature. However, on oxygen-precovered Cu(100), all of the adsorbed ClCH2CH2OH molecules below 0.5 langmuir exposures completely dissociate to generate ethylene and acetaldehyde via the intermediate of ClCH2CH2O-. The computational studies predict that the ClCH2CH2O- is most likely to be adsorbed at the 4-fold hollow sites of Cu(100), with its C-O bond only slightly titled away from the surface normal and with a gauche conformation with respect to the C-C bond. The hollow-site ClCH2CH2O- has an adsorption energy that is 4.4 and 19.2 kcal x mol(-1) lower than that of the ClCH2CH2O- bonded at the bridging and atop sites, respectively. No significant effect of precovered oxygen on the ClCH2CH2O- bonding geometry and infrared band frequencies has been observed, as compared with the case without oxygen. 相似文献
995.
996.
Subergane‐Type Sesquiterpenes from Gorgonian Coral Subergorgia suberosa with Antibacterial Activities 下载免费PDF全文
Qixi Huang Wei Cheng Hailin Long Huagang Liu Leen van Ofwegen Wenhan Lin 《Helvetica chimica acta》2015,98(9):1202-1209
A new subergane‐type sesquiterpene, named epoxysubergorgic acid ( 1 ), along with seven known sesquiterpenes, were isolated from the gorgonian coral Subergorgia suberosa. The structure of the new compound was determined by extensive spectroscopic analyses. The previously uncertain absolute configuration of the known analogues 2 – 6 was determined on the basis of CD, Mosher's method, and through chemical conversions. All compounds were evaluated for antibacterial activities. 相似文献
997.
Discrete Rectangles,Prisms, and Heterometallic Cages from a Conjugated Cp*Rh‐Based Building Block 下载免费PDF全文
Xu‐Yu Shen Dr. Ying‐Ying Zhang Long Zhang Dr. Yue‐Jian Lin Prof. Guo‐Xin Jin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(47):16975-16981
By carefully selecting an existing synthetic strategy and suitable coordination subunits, constructing desired coordination geometries is no longer that difficult to accomplish. Herein, a new strategy to construct a series of unprecedented structures by using conjugated Cp*Rh‐based complex BN‐OTf (Cp*=η5‐C5Me5) as the building block is proposed. DFT calculations revealed extensive delocalized π bonds in the subunit. With BN‐OTf , rectangular macrocycles TN‐bpy and TN‐bpe were controllably synthesized. Single‐crystal XRD studies confirmed one‐dimensional stacking channels for the tetranuclear structure. Notably, the starting ligand imidazole‐4,5‐dicarboxylate was found to act not only as a tetradentate but also as a hexadentate ligand that can coordinate to further metal ions. Subsequently, [4 Rh+1 M] heterometallic complexes HMZ (M=Cu and Zn) were accessed by chelating borderline hard/soft Lewis acids. With TN‐Linker or HMZ , two routes resulted in the [8 Rh+2 M] heterometallic cages HMC (M=Cu and Zn) with excellent crystallinity and stability. Surprisingly, when BN‐OTf bonded to rhodium itself, triangular prisms TP‐Linker were obtained with high solubility after being linked by bipyridine linkers. Both the X‐ray structure and 1H NMR spectrum confirmed the novel isomerization of the triangular structures. All of the compounds were obtained in high yields and were fully characterized by 1H NMR spectroscopy, elemental analysis, IR spectroscopy, and in most cases single‐crystal X‐ray structure determination. 相似文献
998.
Phenyltriazolinones are one of the most important classes of herbicides targeting the protoporphyrinogen oxidase enzyme. A series of triazolinone derivatives containing a strobilurin pharmacophore were designed and synthesized with the aim of discovering new phenyltriazolinone analogues with high activity. The herbicidal activity of the synthesized compounds was assayed and some of the test compounds displayed moderate herbicidal activity at 150 g ai/ha. 相似文献
999.
Krow GR Liu N Sender M Lin G Centafont R Sonnet PE DeBrosse C Ross CW Carroll PJ Shoulders MD Raines RT 《Organic letters》2010,12(23):5438-5441
CD spectra for homooligomers (n = 4, 6, 8) of (1S,4R,5R)-5-syn-carboxy-2-azabicyclo[2.1.1]hexane (MPCA), a methano-bridged pyrrolidine β-carboxylic acid, suggest an ordered secondary structure. Even in the absence of internal hydrogen bonding, solution NMR, X-ray, and in silico analyses of the tetramer are indicative of conformations with trans-amides and C(5)-amide-carbonyls oriented toward the C(4) bridgehead. This highly constrained β-amino acid could prove useful in the ongoing development of well-defined foldamers. 相似文献
1000.
In this paper we report the anaerobic Escherichia coli biofilm formation on solid substrate under redox-controlled extracellular environment by an electrochemical quartz crystal microbalance (EQCM) method. Both biomass and electrochemical activity were monitored in situ. Larger biomass was yielded under redox-controlled condition comparing with natural biofilm growth, which was also confirmed by optical observation. Surface-colonizing cells responded more sensitively to their redox environment than planktonic cells. Cyclic voltammogram (CV) obtained during the time course of biofilm development indicates the emergence of redox active phenotype under redox-controlled condition but not in natural condition. Our results suggest an effective means to control biofilm development with desired metabolic adaptation and also to in situ monitor the biomass yield and the emergent catalytic property simultaneously. 相似文献