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1.
ABEEM/MM model has been applied to compute the various properties characterizing water clusters (H2O)
n
(n = 7−10), such as optimized geometries, the hydrogen bonds number, cluster interaction energies, stabilities, ABEEM charge
distributions, dipole moments, structural parameters, and so on, and to describe the transition reflected by the hexamer region
from two-dimensional (from dimer to pentamer) to three-dimensional structures (for clusters larger than the hexamer).
Supported by the National Natural Science Foundation of China (Grant No. 20373021) 相似文献
2.
A series of novel heteronuclear Ln(III)-CU(II) complexes with noncyclic polyether-amino acid Schiff base were synthesized.
The general formula is (LnCu2(H2TALY) (NO3)5] (NO3)2·nH2O (Ln= La, Nd, Sm, Gd,n = 4; Ln = Yb, Y,n = 3), where H2TALY = tetraglycol aldehyde bis-lysine Schiff base. It is the first time to report the synthetic method for this new Cu(II)
complexes and Ln(III)-Cu(II) heteronuclear complexes. The complexes were characterized by elemental analysis, IR spectra.
TG-DTA, magnetic susceptibility, and especially by a 500 MHz NMR spectrometer for 2D-COSY NMR. Coordination mechanism and
structures of complexes have been suggested as well. Of particular interest is the potential that the novel complexes obtained
may be used as a catalyst. which prompted us to investigate them. It shows 100% conversion with the viscosity-average molecular
weight 120 000 for the polymerization of methyl methacrylate (MMA) without addition of any cocatalyst. Furthermore, the complexes
with such aliphatic Schiff bases can be used as a good catalyst, which has been confirmed and discussed here. They may be
a new kind of catalyst system with the above speciality.
Project supported by the National Natural Science Foundation of China (Grant No. 29671026) and Natural Science Foundation
of Zhejiang Province (Grant No. 296062) and the Laboratory of MRAMP (Grant No. 971502). 相似文献
3.
Two supramolecular complexes,[Ni(rac-L)]3[CrO4]2[ClO4]2-4H2O (1) and [meso-H2L]0.5[VO3]-0.16H2O (2) (L= 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetra-decane),have been prepared in an aqueous solu-tion,and detected by elemental analysis,IR,TG,and single crystal X-ray diffraction analyses. Com-pound 1 shows a one-dimensional hexagonal prism formed by the hydrogen bonding interactions between the secondary amines of rac-L and CrO42-anion/water molecules. Compound 2 displays a three-dimensional structur... 相似文献
4.
ZhengShuai Bai ShuiSheng Chen ZhengHua Zhang ManSheng Chen GuangXiang Liu WeiYin Sun 《中国科学B辑(英文版)》2009,52(4):459-464
Two novel interpenetrated coordination polymers, [Zn(IBA)2]
n
(1) and {[Cd(IBA)2(H2O)]·4H2O}
n
(2), have been synthesized by using 4-imidazole-benzoic acid (HIBA) as ligand under hydrothermal conditions. Complex 1 crystallizes
in a chiral space group and has a two-fold interpenetrated 2D network structure with (4,4) topology, while complex 2 is a
3D porous dia network with four nets interpenetrating each other. The SHG activity of 1 and the photoluminescent property
of 2 have been investigated.
Supported by the National Natural Science Foundation of China (Grant Nos. 20731004 & 20721002) and the National Basic Research
Program of China (Grant No. 2007CB925103) 相似文献
5.
O. I. Arillo-Flores M. F. Ruiz-López M. I. Bernal-Uruchurtu 《Theoretical chemistry accounts》2007,118(2):425-435
We discuss the failure of commonly used AM1 and PM3 semiempirical methods to correctly describe acid dissociation. We focus
our analysis on HCl because of its physicochemical importance and its relevance in atmospheric chemistry. The structure of
non-dissociated and dissociated HCl – (H2O)
n
clusters is accounted for. The very bad results obtained with PM3 (and also with AM1) are related to large errors in gas-phase
proton affinity of water and gas-phase acidity of HCl. Indeed, estimation of pKa values shows that neither AM1 nor PM3 are able to predict HCl dissociation in liquid water since HCl is found to be a weaker
acid than H3O+. We have proposed in previous works a modified PM3 approach (PM3-MAIS) adapted to intermolecular calculations. It is derived
from PM3 by reparameterization of the core–core functions using ab initio data. Since parameters for H–Cl and O–Cl core–core
interactions were not yet available, we have carried out the corresponding optimization. Application of the PM3-MAIS method
to HCl dissociation in HCl–(H2O)
n
clusters leads to a huge improvement over PM3 results. Though the method predicts a slightly overestimated HCl acidity in
water environment, the overall agreement with ab initio calculations is very satisfying and justifies efforts to develop new
semiempirical methods. 相似文献
6.
Shiyu Tan Yang Yang Ziping Luo Shuo Zhao Dafu Huang Jun Zhang Lichun Dong Gang Wang 《Chemical Papers》2011,65(4):510-518
p-Aminobenzene sulfonamide (sulfanilamide, SN) is the simplest and most-used sulfonamide medicine. The key step of SN production
via the commonly used chlorosulfonic acid routine is the synthesis of p-acetaminobenzenesulfonyl chloride (P-ASC). A large amount of HSO3Cl has to be used in the traditional process, which results in serious environmental problems. In this study, an alternative
chlorosulfonic acid process to synthesize P-ASC was investigated by partially substituting HSO3Cl by PCl5 as the chlorination agent. Compared with the traditional process, the molar ratio of HSO3Cl to acetanilide (the main raw material) can be decreased from 4.96 to 2.1 using CCl4 as the diluent; also, addition of a small amount of NH4Cl was found to significantly increase the P-ASC yield. Operating conditions of the reaction were studied first by single-factor
experiments and later by orthogonal experiments to obtain optimum operating conditions under which the P-ASC yield can reach
as high as 86.3 %. 相似文献
7.
Wheat gluten (WG)/silica (SiO2) hybrids were prepared through in-situ synthesis of SiO2 in WG dispersion of aqueous ammonia. The hybrids with different SiO2 contents were mixed with glycerol plasticizer to form cohesive dough and the dough was compressively molded to form cross-linked
sheets. Morphology, moisture absorption, protein solubility in water, tensile mechanical properties and dynamic rheological
behavior of the WG/SiO2 composites were investigated in relation to SiO2 contents.
Supported by the National Natural Science Foundation of China (Grant No. 50773068) and Natural Science Foundation of Zhejiang
Province (Grant No. Y407011) 相似文献
8.
IR spectra of 24 structural isomers of (HF)
n
(n=4–8) clusters were calculated in the framework of semiempirical theory of polyatomic molecule vibrations. Based on the results
obtained and available experimental data it is proposed that (HF)
n
associates comprising 3–5-membered cycles with attached monomeric HF units are present in molecular beams and gas phase.Ab initio calculations performed by the SCF method show the existence of local minima corresponding to such structures on the potential
energy surface of (HF)
n
clusters (n=4–6).
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 435–443, March, 1997. 相似文献
9.
Kr atoms were produced in their metastable states 4p55s [3/2]2 and 4p55s’ [1/2]0 in a pulsed DC discharge in a beam, and subsequently excited to the even-parity autoionizing Rydberg states 4p5
np′ [3/2]1,2, [1/2]1 and 4p5
nf′ [5/2]3 using single photon excitation. The excitation spectra of the even-parity autoionizing resonance series from the metastable
Kr were obtained by recording the autoionized Kr+ ions with time-of-flight ion detection in the photon energy range of 29000–40000 cm−1. A wealth of autoionizing resonances were newly observed, from which more precise and more systematic spectroscopic data
of the level energy and quantum defects were derived.
Supported by the National Natural Science Foundation of China (Grant No. 20673107), the National Key Basic Research Special
Foundation of China (Grant No. 2007CB815203), and Chinese Academy of Sciences (Grant No. KJCX2-SW-H08) 相似文献
10.
E. I. Goryunov A. M. Safiulina V. P. Morgalyuk I. B. Goryunova G. N. Molchanova T. V. Baulina E. I. Matrosov P. V. Petrovskii I. G. Tananaev E. E. Nifant’ev B. F. Myasoedov 《Russian Chemical Bulletin》2008,57(2):383-388
N-(n-Alkyl)-N′-diphenylphosphorylureas Ph2P(O)NHC(O)NHC
n
H2n+1 (n = 6–10) were synthesized by the reaction of diphenylphosphoryl isocyanate with primary n-alkylamines C
n
H2n+1NH2. The products (especially N-diphenylphosphoryl-N′-n-octylurea) are efficient extractants capable of extracting actinides and lanthanides from nitric acid solutions with high
distribution coefficients.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 374–379, February, 2008. 相似文献
11.
In‐Sun Jeon Doo‐Sik Ahn Sung‐Woo Park Sungyul Lee Bongsoo Kim 《International journal of quantum chemistry》2005,101(1):55-66
Calculations are presented for the structure and the isomerization reaction of various conformers of the bare serine, neutral serine–(H2O)n and serine zwitterion–(H2O)n (n = 1, 2) clusters. The effects of binding water molecules on the relative stability and the isomerization processes are examined. Hydrogen bonding between serine and the water molecule(s) may significantly affect the relative stability of conformers of the neutral serine–(H2O)n (n = 1, 2) clusters. The sidechain (OH group) in serine is found to have a profound effect on the structure and isomerization of serine–(H2O)n (n = 1, 2) clusters. Conformers with the hydrogen bonding between water and the hydroxyl group of serine are predicted. A detailed analysis is presented of the isomerization (proton transfer) pathways between the neutral serine–(H2O)2 and serine zwitterion–(H2O)2 clusters by carrying out the intrinsic reaction coordinate analysis. At least two water molecules need to bind to produce the stable serine zwitterion–water cluster in the gas phase. The isomerization for the serine–(H2O)2 cluster proceeds by the concerted double and triple proton transfer mechanism occurring via the binding water molecules, or via the hydroxyl group. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
12.
A novel capacitive sensor for pazufloxacin mesilate (pazufloxacin) determination was developed by electropolymerizing p-aminobenzene sulfonic (p-ABSA) and molecularly imprinted polymers (MPs), which was synthesized through thermal radical copolymerization of metharylic
acid (MAA) and ethylene glycol dimethacrylate (EGDMA) in the presence of pazufloxacin template molecules, on the gold electrode
surface. Furthermore, 1-dedecanethiol was used to insulate the modified electrode. Alternating current (ac) impedance experiments
were carried out with a Model IM6e to obtain the capacitance responses. Under the optimum conditions, the sensor showed linear
capacitance response to pazufloxacin in the range of 5 ng·mL−1 to 5 μg·mL−1 with a relative standard deviation (RSD) 5.3% (n=7) and a detection limit of 1.8 ng·mL−1. The recoveries for different concentration levels of pazufloxacin samples varied from 94.0% to 102.0%. Electrochemical experiments
indicated the capacitive sensor exhibited good sensitivity and selectivity and showed excellent parameters of regeneration
and stability.
Supported by the National Natural Science Foundation of China (Grant No. 20675064), the Natural Science Foundation of Chongqing
City (Grant No. CSTC-2004BB4149 and 2005BB4100) and High Technology Project Foundation of Southwest University (Grant No.
XSGX02). 相似文献
13.
A time-dependent quantum wave packet method was used to study the dynamics of dissociative adsorption of H2 and D2 on a flat and static surface. The molecule-surface interaction is described using a modified London-Eyring-Polanyi-Sato (LEPS)
type potential for the H2/Ni(100) system. The three-dimensional (3-D) dissociation probabilities were calculated for different initial rovibrational
states as a function of initial incident energies. Our results show that the dissociation of the diatomic rotational states
whose quantum numbers satisfyj+m = odd is forbidden at low energies for the homonuclear Hz and D2 due to the selection rule. The effect of the rotational orientation of diatoms on adsorption predicts that the in-plane rotation
(m = j) is more favorable for dissociation than the out-of-plane rotation (m = 0). Enhanced dissociation for vibrationally excited molecules and the significant enhancement of the dissociation probability
of H2 when compared to D2 were explained reasonably in terms of quantum mechanical zero-point energies, the tunneling effect and the reflection from
an activation barrier.
Project supported by the National Natural Science Foundation of China (Grant No. 19694033) and partially by the Science Foundation
for Overseas Chinese Scholars and Students, administered by the State Education Commission of China (Grant No. 1992), by the
State Key Laboratory of Theoretical and Computational Chemistry of Jilin University at Changchun (Grant No. 98011, and by
the Natural Science Foundation of Shandong Province (Grant No. Y96B03022) 相似文献
14.
Ternary clusters (NH3)·(H2SO4)·(H2O)n have been widely studied. However, the structures and binding energies of relatively larger cluster (n > 6) remain unclear, which hinders the study of other interesting properties. Ternary clusters of (NH3)·(H2SO4)·(H2O)n, n = 0-14, were investigated using MD simulations and quantum chemical calculations. For n = 1, a proton was transferred from H2SO4 to NH3. For n = 10, both protons of H2SO4 were transferred to NH3 and H2O, respectively. The NH4+ and HSO4− formed a contact ion-pair [NH4+-HSO4−] for n = 1-6 and a solvent separated ion-pair [NH4+-H2O-HSO4−] for n = 7-9. Therefore, we observed two obvious transitions from neutral to single protonation (from H2SO4 to NH3) to double protonation (from H2SO4 to NH3 and H2O) with increasing n. In general, the structures with single protonation and solvated ion-pair were higher in entropy than those with double protonation and contact ion-pair of single protonation and were thus preferred at higher temperature. As a result, the inversion between single and double protonated clusters was postponed until n = 12 according to the average binding Gibbs free energy at the normal condition. These results can serve as a good start point for studies of the other properties of these clusters and as a model for the solvation of the [H2SO4-NH3] complex in bulk water. 相似文献
15.
《中国科学B辑(英文版)》2008,(4)
Ionic dissociation of chlorosulfonic acid (HSO3Cl) in the molecular clusters HSO3Cl-(H2O)n (n = 1-4) and HSO3Cl-NH3-(H2O)n (n = 0-3) was investigated by density functional theory and ab initio molecular orbital theory. The equilibrium structures, binding energies, and thermodynamic properties, such as relative enthalpy and relative Gibbs free energy, and were calculated using the hybrid density func- tional (B3LYP) method and the second order M?ller-Plesset approximation (MP2) method with the 6-311 G** basis set. Chlorosulfonic acid was found to require a minimum of three water molecules for ionization to occur and at least one water molecule to protonate ammonia. The corresponding clusters with fewer water molecules were found to be strongly hydrogen-bonded. The related properties and acid strength of chlorosulfonic acid were discussed and compared to the acid strengths of perchloric acid and sulfuric acid in the context of clusters with ammonia and water. The relative stabilities of these clusters were also investigated. 相似文献
16.
The fluorophobic effect of the semi-fluorinated chain of discotic molecules efficiently improves the stability of columnar mesophase.Low symmetric discogens exhibit decreased melting points and wide mesophase ranges.A series of triphenylene derivatives 1,C18H6(OCnH2n+1)4(OMe)(O2CC2H4C6F13),and their hydrocarbon analogues 2,C18H6(OCnH2n+1)4(OMe)(O2CC8H17),n = 4―8,were synthesized for the investigation of the influence of semi-fluorinated peripheral chain and molecular symmetry on mesomorphism.The structures ... 相似文献
17.
Two new neodymium complexes, [Nd2(abglyH)6(2,2′-bipy)2(H2O)2] · 4H2O 1 and {[Nd(abglyH)3(H2O)2] · (4,4′-bipy) · 7H2O}n
2 (abglyH2 = N-P-acetamidobenzenesulfonyl-glycine acid, 2,2′-bipy = 2,2′-bipyridine, 4,4′-bipy = 4,4′-bipyridine), have been synthesized and
their structures have been measured by X-ray crystallography. In 1, nine-coordinated Nd(III) ions are bridged by two syn–syn bidentate and two tridentate bridging carboxylate groups from four different abglyH− anions to form dinuclear motifs, which are further connected into a 3-D supramolecular framework via hydrogen bonds between
the binuclear motifs and the uncoordinated water molecules. In 2, eight-coordinated Nd(III) ions are linked by six carboxylate groups adopting a syn–syn bidentate bridging fashion to form a 1-D inorganic–organic alternating linear chain. These polymeric chains generate microchannels
extending along the a direction, and these cavities are occupied by discrete tetradecameric water clusters, which interact with their surroundings
and finally furnish the 3-D supramolecular network via hydrogen bonds. At the same time, π–π stacking interactions between
benzene rings from abglyH− anions also play an important role in stabilizing the network. 相似文献
18.
Reactions of N-tosylimidoyl chlorides with the Schiff bases of the general formula TsNH(CH2)nN=CHR (n = 2 or 3; R = Pri, 4-MeOC6H4, 4-Me2NC6H4, and 3-O2NC6H4) afforded 2-substituted 1-tosyl-3-(1-tosyliminoalkyl)imidazolidines (n = 2) or-hexahydropyrimidines (n = 3).
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 872–875, May, 2006. 相似文献
19.
A new compound of C17H20FN3O32+ · 2HSO4−·H2O [ciprofloxacindi-um bis(hydrosulfate) monohydrate], C17H18FN3O3 1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinolinecarboxylic acid (CfH, ciprofloxacin) is obtained and
its crystal structure is determined. The crystal contains CfH32+ and HSO4− ions and crystallization water molecules. Hydrogen (H3), which forms an intramolecular hydrogen bond with oxygen O2 of the
carboxyl group, is attached to the carbonyl O1 atom. Hydrogen H4 of the carboxyl group is hydrogen bonded to the crystallization
water molecule which links CfH32+ with two HSO4− groups by hydrogen bonds. Both H atoms at N3 of the piperazine ring form hydrogen bonds with two oxygen atoms of other HSO4− anions. Intramolecular hydrogen bonds of two types are present in the CfH32+ cation. One of them forms a six-membered ring, bonding O1 and O2 atoms, while the other, also enclosing a six-membered ring,
links fluorine and carbon C14 atoms.
Original Russian Text Copyright ? 2009 by A. D. Vasiliev, N. N. Golovnev, and I. A. Baidina
__________
Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 1, pp. 165–168, January–February, 2009. 相似文献
20.
Dr. Attila Bende Dr. Giuseppe Perretta Dr. Paolo Sementa Dr. Tonia M. Di Palma 《Chemphyschem》2015,16(14):3021-3029
The influence of carboxylic acids on water nucleation in the gas phase has been explored in the supersonic expansion of water vapour mixed with acetic acid (AcA) at various concentrations. The sodium‐doping method has been used to detect clusters produced in supersonic expansions by using UV photoionisation. The mass spectra obtained at lower acid concentrations show well‐detected Na+?AcA(H2O)n and Na+?AcA2(H2O)n clusters up to 200 Da and, in the best cooling expansions, emerging Na+?AcAm(H2O)n signals at higher masses and unresolved signals that extend beyond m/e values >1000 Da. These signals, which increase with increasing acid content in water vapour, are an indication that the cluster growth taking place arises from mixed water–acid clusters. Theoretical calculations show that small acid–water clusters are stable and their formation is even thermodynamically favoured with respect to pure water clusters, especially at lower temperatures. These findings suggest that acetic acid may play a significant role as a pre‐nucleation embryo in the formation of aerosols in wet environments. 相似文献