排序方式: 共有16条查询结果,搜索用时 15 毫秒
1.
Khaldoun A. Al-Sou'od Basem F. Ali Rajab Abu-El-Halawa Abd-Al-Hakeem H. Abu-Nawas 《国际化学动力学杂志》2005,37(7):444-449
Kinetics and mechanism of oxidation of benzoin (H2B) by ferrozine (Fz) or 2,2'‐bipyridine (bipy) have been carried out in aqueous HNO3 medium. The rate shows first‐order dependence on [H2B] and [Fe3+] and inverse second‐order dependence on [H+]. The rate of reaction increased with increase in the ligand concentration. The increase in dielectric constant will increase the rate, while increase in [HNO3] decreased it. Substituent and temperature effects on the rates have been investigated. The rate laws derived are in excellent agreement with the experimental results. Plausible mechanisms are suggested. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 444–449, 2005 相似文献
2.
Ameer Ghuzlaan Mahmoud M. Al Omari Khaldoun A. Al-Sou’od 《Journal of solution chemistry》2009,38(1):83-94
Guest–host interaction of prednisone (PN) with cyclodextrins (CDs) have been investigated using phase solubility diagrams
(PSD), differential scanning calorimetry (DSC), X-ray powder diffractometry (XRPD), scanning electron microscopy (SEM) and
molecular mechanical modeling (MM). Estimates of the complex formation constant (K
11) show that the tendency of PN to complex with CDs follows the order: β-CD>γ-CD>HP-β-CD>α-CD. At the same pH of 7.0, β-CD forms soluble 1:1 and insoluble 1:2 PN/CD complexes (BS-type PSDs). The thermodynamic functions for 1:1 PN/β-CD estimated at pH = 7.0 (ΔG
11o=−20.8 kJ⋅mol−1) show that complexation is driven by enthalpy (−30.7 kJ⋅mol−1) but retarded by entropy (ΔS
11o=−33.1 J⋅mol−1⋅K−1) changes. The MM modeling study indicates the formation of different isomeric 1:1 complexes with CDs. PSD, DSC, XRPD, SEM
and MM studies established the formation of inclusion complexes in solution and the solid state. 相似文献
3.
Khaldoun A. Al-Sou’od Mohammad B. Zughul Adnan A. Badwan 《Journal of solution chemistry》2006,35(10):1377-1388
Phase solubility diagrams (PSDs) at 25 ∘C and molecular mechanical (MM) modeling were used to study the aqueous complexation of some 2H- and 3H-indole derivatives with β-cyclodextrin (β-CD). Among the 3H-indole derivatives investigated in this work, indole-3H-butyric acid forms the most stable 1:1 complex of the B
s
-type PSD, whereas shorter chain derivatives form soluble 1:1 complexes (A
L
-type PSDs) with their stability increasing as the chain length increases. Indole-2 carboxylic acid forms highly stable 1:1 and 1:2 complexes, with the lower-order complex reaching saturation first (B
s
-type PSD). MM modeling indicates that the stability of the complex is highly correlated with the flexibility of the 3H-indole hydrocarbon chain, which yields a better geometrical fit within the β-CD cavity resulting from different hydrophilic interactions. These interactions are represented in the H-bonding of the carboxyl group with the primary hydroxyl group network that is situated at the narrow rim of the cavity, and also by a favorable interaction of the aromatic ring with the hydroxyl group network at the other rim. 相似文献
4.
Khaldoun A. Al-Sou’od 《Journal of inclusion phenomena and macrocyclic chemistry》2006,54(1-2):123-127
Molecular mechanics calculations were employed to study the inclusion of some 1,2,4-oxadiazol derivatives in β-cyclodextrin
in vacuum and in the presence of water as a solvent using MM + force field. The driving forces for complexation in both environments
are dominated by nonbonded van der Waals host–guest interactions with little electrostatic contribution. Among 1,2,4-oxadiazole
derivatives investigated in this work, 3,3′-bis(1,2,4-oxadiazol-5(4H)-one) (H2OD) forms the least stable 1:1 complex and the stability increases as the chain length increases. 相似文献
5.
Rawhi Al-Far Basem F. Ali Mukarram H. Zaghal Razan M. Mhaidat Zaher Judeh Khaldoun Al-Sou'od 《Journal of chemical crystallography》2006,36(1):41-46
The title compound, cis-[Rh(biq)2Cl2]Cl·3H2O (biq = 2,2′-biquinoline) crystallized in the monoclinic space group P2
1
/n with a = 11.231(2) Å, b = 20.895(4) Å, c = 14.081(3) Å, β = 94.76(3)°, V = 3293.0(11) Å3, D
c = 1.565 g cm−3, μ = 0.806 mm−1, F(000) = 1576 and Z = 4. It contains a monomeric [Rh(biq)2Cl2]+ cation, a chloride ion and three molecules of H2O. The rhodium(III) ion is hexa coordinated forming a distorted octahedral arrangement. The mean Rh(III)–N distance for the four Rh(III)–N bonds is 2.0625 Å. The two chloride atoms are bonded in a cis configuration [Rh(III)–Cl bond distances are 2.329(3) and 2.341(4) Å]. The structure shows a curling stacks of cationic complexes interacting via offset-face-to-face (OFF) π–π aryl interaction motif. Water molecules and chloride ions are hydrogen bonded (H2O···H–OH and Cl···H–OH) and links the curling stacks by hydrogen bonding via Rh–Cl···H–OH interactions. 相似文献
6.
Félix G Abdul-Kader K Mahfoud T Gural'skiy IA Nicolazzi W Salmon L Molnár G Bousseksou A 《Journal of the American Chemical Society》2011,133(39):15342-15345
Nano-objects and thin films displaying molecular spin-crossover phenomena have recently attracted much attention. However, the investigation of spin crossover at reduced sizes is still a big challenge. Here we demonstrate that surface plasmon polariton waves propagating along the interface between a metal and a dielectric layer can be used to detect the spin-state changes in the latter with high sensitivity, even at the nanometer scale. 相似文献
7.
Nonlinear phenomena occurring in an optical fiber ring resonator featuring ultrahigh Q factor are experimentally studied. The laser is locked onto the resonator, and the optical power induced in the resonator is controlled. The onset of the first stimulated Brillouin scattering wave occurs at an optical input power as low as -9 dBm in these resonators. When the resonator is used as the frequency reference device in an optoelectronic oscillator (OEO), it has been found that these parasitic signals mix with the OEO signal and degrade its phase noise. More than 20 dB improvement of the OEO phase noise has been demonstrated by limiting these nonlinear optical effects. 相似文献
8.
Amjad M. Qandil Aiman A. Obaidat Muaadh A. Mohammed Ali Bashar M. Al-Taani Bassam M. Tashtoush Nawzat D. Al-Jbour Mayyas M. Al Remawi Khaldoun A. Al-Sou’od Adnan A. Badwan 《Journal of solution chemistry》2009,38(6):695-712
Complexation between ibuprofen and low molecular weight chitosan (LMWC) was studied. LMWC was prepared from high molecular
weight chitosan using the acid hydrolysis method. The complexes were investigated by using DSC, FT-IR and liquid-state 1H-NMR. Molecular mechanics (MM) calculations were used to give insight into the stoichiometry of the interaction of chitosan
with ibuprofen. The results showed that complexation of ibuprofen with LMWC involves ionic interaction between the ammonium
group of LMWC and the carboxylate anion of ibuprofen. It was also shown that it is more efficient to prepare the complexes
using lower concentration solutions of the polymer. These results were supported by molecular mechanics calculations. The
experimental results may explain the discrepancies in the literature where, in many studies, the concentration of chitosan
and its low average molecular weight were not considered to be important factors in the complexation process. 相似文献
9.
Zazoua Hanane Touahra Fouzia Sehailia Moussa Chebout Redouane Lerari Djahida Bachari Khaldoun Saadi Adel 《Research on Chemical Intermediates》2019,45(5):3273-3290
Research on Chemical Intermediates - Delafossite mixed metal oxides of the form BaCuO2 and BaCu1M1?xO2 (M?=?Ni, Fe and Co) were successfully synthesized following a sol–gel... 相似文献
10.
Rana Obaidat Nawzat Al-Jbour Khaldoun Al-Sou’d Kamal Sweidan Mayyas Al-Remawi Adnan Badwan 《Journal of solution chemistry》2010,39(4):575-588
Depolymerization for different time intervals of high molecular weight chitosan using 2 mol⋅L−3 HCl resulted in low molecular weight (LMW) chitosan of 6, 10, 13, 18, and 30 kDa. These were studied using the FT-IR which
indicated that the depolymerization process did not influence the chemical structure. LMW chitosan increases the surface tension
of water but adjusting the ionic strength (1% NaCl) caused LMW chitosan to reduce the water surface tension. The zeta potential
increased with increasing concentration up to a maximum in 1% NaCl solutions. Particle size showed a reduction in size with
increasing concentration. This behavior in reduction of particle size was similar to that for the stiffness parameters. These
physico-chemical properties showed that LMW chitosan was present in low concentration in its extended form while in higher
concentrations it adopted a more contracted form. This change in conformation was confirmed by using molecular modeling where
LMW chitosan is ribbon-like to rod-like in solution but becomes rod-like to spherical at the gas–liquid interface. 相似文献