共查询到20条相似文献,搜索用时 15 毫秒
1.
Dr. Qian Gou Lorenzo Spada Prof. Juan Carlos Lòpez Prof. Jens‐Uwe Grabow Prof. Walther Caminati 《化学:亚洲杂志》2015,10(5):1198-1203
The rotational spectra of four isotopologues of the 1:1 complex between chloromethane and water revealed the presence of only one rotamer in a pulsed jet expansion. The two subunits are linked through two weak hydrogen bonds, O? H???Cl (RH???Cl=2.638(2) Å) and C? H???O (RH???O=2.501(2) Å), forming a five‐membered ring. All transitions display the hyperfine structure due to the 35Cl (or 37Cl) nuclear quadrupole effects. Dynamical features in the spectrum are caused by two large‐amplitude motions. Each component line appears as an asymmetric doublet with a relative intensity ratio of 1:3. The splittings led to the determination of barrier to internal rotation of water around its symmetry axis, V2=320(10) cm?1. Finally, an unexpected small value of the inertial defect (?0.96 uÅ2 rather than ?3.22 uÅ2) allowed the estimation of the barrier to the internal rotation of the CH3 group, V3≈8 cm?1. 相似文献
2.
Dr. Nasrollah Rezaei-Ghaleh 《ChemistryOpen》2022,11(6):e202200080
Living cells often contain compartments with high concentration of charged biomolecules. A key question pertinent to the function of biomolecules is how water dynamics are affected by interaction with charged molecules. Here, we study the dynamical behavior of water in an extreme condition, that is, in saturated salt solutions, where nearly all water molecules are located within the first hydration layer of ions. To facilitate disentangling the effects of cations and anions, our study is focused on alkali chloride solutions. Following a multi-nuclear NMR approach enabling direct monitoring of protons and the quadrupolar nuclei 7Li, 17O, 23Na, 35Cl, 87Rb and 133Cs, we investigate how the translational and rotational mobility of water molecules, chloride anion and corresponding cations are affected within the constrained environment of saturated solutions. Our results indicate that water molecules preserve a large level of mobility within saturated alkali chloride solutions that is significantly independent of adjacent ions. 相似文献
3.
Internal Dynamics in Halogen‐Bonded Adducts: A Rotational Study of Chlorotrifluoromethane–Formaldehyde
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Dr. Qian Gou Dr. Gang Feng Dr. Luca Evangelisti Dr. Montserrat Vallejo‐López Lorenzo Spada Prof. Dr. Alberto Lesarri Dr. Emilio J. Cocinero Prof. Dr. Walther Caminati 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(10):4148-4152
The rotational spectra of two isotopologues of the 1:1 complex between chlorotrifluoromethane and formaldehyde have been recorded and analyzed by using Fourier‐transform microwave spectroscopy. Only one rotamer was detected, with the two constituent molecules held together through a Cl???O halogen bond (RCl???O=3.048 Å). The dimer displays two simultaneous large‐amplitude intramolecular motions. The internal rotation of formaldehyde around its symmetry axis (V2=28(5) cm?1) splits all the rotational transitions into two component lines with a relative intensity ratio of 1:3. On the other hand, the almost free internal rotation (V3≈2.5 cm?1) of the CF3 symmetric top increases the “rigid” value of the rotational constant A by almost one order of magnitude. In addition, all the transitions display a hyperfine structure due to the 35Cl (or 37Cl) nucleus quadrupole effects. 相似文献
4.
The microwave spectrum of (35Cl,11B)-1-chloroborepin was obtained and the rotational constants in the ground state derived. The principal moments of inertia obtained from the rotational constants were used to calculate the inertia defect Δ=−0.19 uÅ2. From this evidence, we conclude that 1-chloroborepin is a planar molecule. 相似文献
5.
Prof. Danuta Kruk Dr. Pawel Rochowski Dr. Elzbieta Masiewicz Dr. Slawomir Wilczynski Milosz Wojciechowski Dr. Lionel M. Broche Prof. David J. Lurie 《Chemphyschem》2019,20(21):2816-2822
1H spin−lattice nuclear magnetic resonance relaxation experiments were performed for five kinds of dermal fillers based on hyaluronic acid. The relaxation data were collected over a broad frequency range between 4 kHz and 40 MHz, at body temperature. Thanks to the frequency range encompassing four orders of magnitude, the dynamics of water confined in the polymeric matrix was revealed. It is demonstrated that translation diffusion of the confined water molecules exhibits a two-dimensional character and the diffusion process is slower than diffusion in bulk water by 3–4 orders of magnitude. As far as rotational dynamics of the confined water is concerned, it is shown that in all cases there is a water pool characterized by a rotational correlation time of about 4×10−9 s. In some of the dermal fillers a fraction of the confined water (about 10 %) forms a pool that exhibits considerably slower (by an order of magnitude) rotational dynamics. In addition, the water binding capacity of the dermal fillers was quantitatively compared. 相似文献
6.
Sulistyo Saputro Kô Takehara Kazuhisa Yoshimura Shiro Matsuoka Narsito 《Electroanalysis》2010,22(23):2765-2768
The electrochemical detection of free chlorine based on the reduction at a gold electrode has been studied. The differential pulse voltammetric curves exhibited well‐defined cathodic peaks. Investigations with this system suggested that the active species in the cathodic reaction is HClO. Excellent reproducibility was demonstrated at pH 5. The peak height could be used for accurate and rapid determination of free chlorine in a sample water. A linear relationship (r2=0.99) was found for the concentration range of 1–5 mg Cl dm?3 and the detection limit was estimated to be 0.04 mg Cl dm?3. 相似文献
7.
Pure rotational transitions were observed in the electronically excited state B 3Π0+ of ICl. This state was populated by optical pumping with a single-mode dye laser. From the observed spectrum precise values of the quadrupole hyperfine coupling constant cqQ of iodine and the effective rotational constant were derived for both isotopes I 35Cl and I 37Cl. 相似文献
8.
《Chemical physics letters》1987,136(6):519-526
High-resolution laser-induced fluorescence spectra of28Si35Cl and 28Si37Cl have been observed in a molecular beam. Accurate constants describing the rotational structure in the X 2Π, ν″ = 1 as well as in the electronically excited B 2Σ+, ν' = 0 state are given. An inverted fine structure was found in the excited state with a spin-splitting constant γ = −31.15±0.19 MHz for Si35Cl and γ = −30.62 ±0.61 MHz for Si37Cl. 相似文献
9.
The rotational spectrum of bromoacetyl chloride, BrCH2COCl, has been assigned using a pulsed molecular beam Fourier transform microwave spectrometer. It has been possible to determine the rotational and quartic centrifugal distortion constants of the energetically favoured conformer (anti-periplanar) as well as the complete bromine and chlorine quadrupole coupling tensors including their off diagonal elements for the following isotopomers: 79BrCH2CO35Cl, 81BrCH2CO35Cl, 79BrCH2CO37Cl, and 81BrCH2CO37Cl. Experimental results are supported by quantum chemical calculations. 相似文献
10.
We fitted published frequency and wave number data for pure rotational and vibration‐rotational spectra, respectively, of 23Na35Cl and 23Na37Cl to derive parameters related to potential energy and to the rotational g factor. For comparison with these experimental data we undertook quantum‐chemical computation of adiabatic corrections, rotational and vibrational g factors, electric dipolar moment and its derivative as a function of internuclear distance in a range near Re as a test of an algebraic approach to spectral analysis; experimental, 0.0287 ± 0.0014, and calculated, 0.02149, values of gr at Re are in moderate agreement. The combined results are discussed from a point of view of computational spectrometry. 相似文献
11.
The microwave rotational spectra of C6H1135Cl and C6H1137Cl have been measured. The rotational constants A, B and C and quadrupole coupling constants were determined. Some structural information was obtained. 相似文献
12.
在aug-cc-pVTZ基组下采用CCSD(T)和B3LYP方法,研究了H2O2+Cl反应,并考虑在大气中单个水分子对该反应的影响.结果表明,H2O2+Cl反应只存在一条生成产物为HO2+HCl的通道,其表观活化能为10.21kJ·mol-1.加入一分子水后,H2O2+Cl反应的产物并没有发生改变,但是所得势能面却比裸反应复杂得多,经历了RW1、RW2和RW3三条通道.水分子在通道RW1和RW2中对产物生成能垒的降低起显著的负催化作用,而在通道RW3中则起明显的正催化作用.利用经典过渡态理论(TST)并结合Wigner矫正模型计算了216.7-298.2 K温度范围内标题反应的速率常数.结果显示,298.2 K时通道R1的速率常数为1.60×10-13cm3·molecule-1·s-1,与所测实验值非常接近.此外,尽管通道RW3的速率常数kRW3比对应裸反应的速率常数kR1大了46.6-131倍,但该通道的有效速率常数k'RW3却比kR1小了10-14个数量级,表明在实际大气环境中水分子对H2O2+Cl反应几乎没有影响. 相似文献
13.
We report the observation and analysis of the rotational spectrum of a 1:1 cluster between 2-aminopyridine and water (AMW) carried out with supersonic expansion Fourier transform microwave spectroscopy at 4.7–16.5 GHz. Measurements of the 2-aminopyridine monomer (AMP) were also extended up to 333 GHz for the room-temperature rotational spectrum and to resolved hyperfine splitting resulting from the presence of two 14N quadrupolar nuclei. Supersonic expansion measurements for both AMP and AMW were also carried out for two synthesized isotopic species with single deuteration on the phenyl ring. Nuclear quadrupole hyperfine structure has also been resolved for AMW and the derived splitting constants were used as an aid in structural analysis. The structure of the AMW cluster was determined from the three sets of available rotational constants and the hydrogen bonding configuration is compared with those for clusters with water of similarly sized single-ring molecules. Experimental results aided by quantum chemistry computations allow the conclusion that the water molecule is unusually strongly bound by two hydrogen bonds, OH...N and O...HN, to the NCNH atomic chain of AMP with the potential to replace hydrogen bonds to the identical structural segment in cytosine and adenine in CT and AT nucleic acid base pairs. 相似文献
14.
The microwave spectrum, rotational constants and centrifugal distortion parameters for CH235ClCO35Cl are reported. The nuclear quadrupole coupling constants of the two non-equivalent Cl atoms were determined from partially resolved quadrupole splittings. The molecule is planar in the conformation studied here and both Cl atoms occupy the trans position as shown from their substitution coordinates. 相似文献
15.
The microwave spectrum of 2-chloroacrylonitrile has been studied in the 26.5–40 GHz region. A total of 99 a- and b-type rotational transitions have been measured and assigned for CH2 =C35Cl(CN),yielding values for the rotational constants (in MHz): A = 6973.27, B = 3148.16, C = 2165.95. For CH2=C37Cl(CN) a total of 53 transitions have been measured and assigned and the rotational constants obtained are (in MHz): A = 6909.35, B = 3081.17, C = 2127.98. The distortion effects have also been studied and the quartic distortion constants have been evaluated. From the observed hyperfine structure, the chlorine nuclear quadrupole coupling constants have been obtained. The structure of vinyl cyanide and vinyl chloride can be transferred to account remarkably well for the observed rotational constants. 相似文献
16.
Experimental studies with molecular beam and LIF techniques have independently shown that the reaction O(1D) + H2 → OH + H passes through a long-lived complex and gives products with small translational and large rotational excitation. We have previously published a statistical algorithm, based on ordinary RRKM theory with angular momentum restrictions included, which was designed to simulate molecular beam experiments. It has now been modified and applied to simulate the experimental rotational OH distributions from O(1D)+H2, measured by Luntz et al. The present study also includes simulation of similar results by Luntz for O(1D) + HCI → OH + Cl. The purely statistical algorithm successfully simulates the apparently non-statistical experimental rotational distributions. For these reactions the total angular momentum conservation. which is applied at the transition state, proves to be decisive for the product energy distributions. 相似文献
17.
The metastable intermediate product, CIONO, which is formed from gaseous CINO and Cl2O at about 203 K, has been detected by microwave spectroscopy. The rotational constants and the inertial defects for the 35Cl and 37Cl species establish that the observed spectrum is that of planar cis CIONO. 相似文献
18.
H. Karlsson 《Journal of Molecular Structure》1976,33(2):227-237
The microwave spectrum of propionyl chloride has been investigated in the region 18.0–40.0 GHz, and transitions due to a cis conformer have been assigned. This form has a heavy atom planar configuration and the methyl group and the carbonyl oxygen atom are cis to each other. Using the substitution structures of propionic acid and acetyl chloride as molecular models for the propionyl chloride molecule, good agreement is found between observed and calculateò effective rotational constants. For the 35Cl species satellite spectra assigned to the first four excited states of the C-C torsional mode have been observed together with the first excited state of the methyl torsional mode. The ground state spectrum has also been assigned for the 37Cl species. Relative intensity measurements yielded the lowest C-C torsional vibration frequency of 86 ± 10 cm?1. The CH3 internal rotation frequency was found to be 197 cm?1. Nuclear quadrupole coupling constants were determined for the ground state of the 35Cl and 37Cl species. From observed A-E splittings of bQ-branch transitions of the first excited state of the methyl torsional mode a barrier to internal rotation was estimated to be V3 = 2480 ± 40 cal mol?1 (867 ± 14 cm?1). 相似文献
19.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1977,33(3-4):463-466
The microwave spectra of gauche form of CH3CH2CH235Cl and CH3CH2CH237Cl have been analysed. The analysis gives refined rotational constants and quartic centrifugal distortion constants. 相似文献
20.
Phase behavior of ternary system involving surfactant‐like ionic liquid 1‐dodecyl‐3‐methylimidazolium chloride ([C12mim]Cl), water, and nonionic surfactant PEO‐PPO‐PEO block copolymer (Pluronic L64) is investigated at 25°C. Hexagonal (H1) and lamellar liquid crystal phase (Lα) are found in [C12mim]Cl/H2O/L64 system by using polarized optical microscopy (POM), small‐angle X‐ray scattering (SAXS) techniques and 2H NMR spectra. The phase structure (H1 phase), which is formed in [C12mim]Cl/H2O binary system, is not changed when L64 with a low concentration is added. However, phase transitions will occur from hexagonal to multiphases of H1 and cubic phases (C), then to Lα+C phases with constant [C12mim]Cl/H2O ratio and increasing L64 concentration. Moreover, at given L64 (5%, 20%) concentration, the lattice parameter of H1 or Lα phase decreases with increasing [C12mim]Cl/H2O ratio. Fourier transform infrared (FTIR) spectra indicate that the H‐bonded network comprising an imidazolium ring, chloride ion and water formed in [C12mim]Cl/H2O binary system is disrupted upon addition of L64. This is helpful to the phase transition, due to the decreasing of interfacial curvature induced by dehydration of hydrated layer after the addition of PEO block of L64. 相似文献