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11.
Vera Deneva 《Molecular physics》2019,117(13):1613-1620
ABSTRACTThe tautomeric optical sensors based on 4-(phenyldiazenyl)naphthalen-1-ol exist in their pure enol tautomeric form as free ligands, while the addition of metal ion fully shifts the equilibrium towards the keto tautomer allowing a red shift in the measured absorbance. This effect is achieved when a side ionophore group is connected to a tautomeric backbone by a spacer in a way that stabilizes the enol form via hydrogen boding. When the ionophore captures the metal ion the keto form is stabilized due to C─O tautomeric group participation in the complex. In the current study, we model theoretically the effect of symmetric tweezer like ionophores (RCOXCOR, where X, being CH or N, is the linker to the tautomeric backbone) on the tautomeric state and complexation ability of 4-(phenyldiazenyl)naphthalen-1-ol containing ligands. It was found that enol form stabilisation is achieved when R?=?NMe2, independing on the linker. Both ligands are unsuitable for capturing alkali metal ions. The calculations predict that the complexation with alkali earth metal ions could lead to a full shift of the tautomeric equilibrium towards keto tautomer. 相似文献
12.
Jian-Ping Li Lian-Zhong Deng Ye Zheng Peng-Peng Ding Tian-Qing Jia Zhen-Rong Sun Jian-Rong Qiu Shi-An Zhang 《Frontiers of Physics》2020,15(2):22603-68
The spectral phase of the femtosecond laser field is an important parameter that affects the up-conversion(UC)luminescence efficiency of dopant lanthanide ions.In this work,we report an experi-mental study on controlling the UC lmiiinescence efficiency in Sm^3+:NaYF4 glass by 800-nm femtosec-ond laser pulse shaping using spectral phase modulation.The optimal phase control strategy efficiently enhances or suppresses the UC luminescence intensity.Based on the laser-power dependence of the UC luminescence intensity and its comparison with the luminescence spectrum under direct 266-nm fem-tosecond lciser irradiation,we propose herein an excitation model combining non-resonant two-photon absorption with resonance-media ted three-photon absorption to explain the experimental observations. 相似文献
13.
J. Bhavya M. S. Vineetha P. M. Sundaram S. M. Veena B. L. Dhananjaya 《液相色谱法及相关技术杂志》2016,39(4):203-208
Snake venom hyaluronidases known as “spreading factor” are not extensively studied. Recently, it is argued that beyond its role as a spreading factor, venom hyaluronidase (HYL) deserves to be explored as a possible therapeutic target for inhibiting the systemic distribution of venom/toxins and also for minimizing local tissue destruction. In this context, in the present study, a low-molecular weight HYL has been isolated from Bungarus caeruleus (Indian krait) venom by single step chromatography on HPLC system. The apparent molecular weight determined by SDS-PAGE is 14 ± 2 kDa, as confirmed by zymogen study and LC–MS as well. The enzyme had optimal pH 6 and temperature 37°C. The Michaelis–Menten constant (Km) was found to be 8.48 µg/mL at 37°C. The activity of purified enzyme was completely inhibited by Ba2+ metal ion and N-acetyl imidazole group-specific agents. This work yielded a highly active HYL from B. caeruleus the first one to be isolated. Further studies on its pharmacological actions will be interesting to develop lead molecules for better management of snakebite. 相似文献
14.
Highly Efficient Copper(II) Ion Sorbents Obtained by Calcium Carbonate Mineralization on Functionalized Cross‐Linked Copolymers 下载免费PDF全文
Dr. Marcela Mihai Dr. Ion Bunia Florica Doroftei Dr. Cristian‐Dragos Varganici Prof. Bogdan C. Simionescu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(13):5220-5230
A new type of CuII ion sorbents is presented. These are obtained by CaCO3 mineralization from supersaturated solutions on gel‐like cross‐linked polymeric beads as insoluble templates. A divinylbenzene–ethylacrylate–acrylonitrile cross‐linked copolymer functionalized with weakly acidic, basic, or amphoteric functional groups has been used, as well as different initial inorganic concentrations and addition procedures for CaCO3 crystal growth. The morphology of the new composites was investigated by SEM and compared to that of the unmodified beads, and the polymorph content was established by X‐ray diffraction. The beads, before and after CaCO3 mineralization, were tested as sorbents for CuII ions. The newly formed patterns on the bead surface after CuII sorption were observed by SEM, and the elemental distribution on the composites and the chemical structure of crystals after interaction with CuII were investigated by EDAX elemental mapping and by FTIR‐ATR spectroscopy, respectively. The sorption capacity increased significantly after CaCO3 crystals growth on the weak anionic bead surface (up to 1041.5 mg CuII/g sample) compared to that of unmodified beads (491.5 mg CuII/g sample). 相似文献
15.
温述龙 《原子与分子物理学报》2015,32(6)
采用基于第一性原理的密度泛函理论(DFT)和局域密度近似(LDA)方法,优化计算得到碳纳米管(CNT),硼原子取代碳原子及其吸附氖原子前后系统的几何结构,能量,电子能带和态密度。结果显示,碳纳米管的能带结构与石墨的层状几何结构相似,能量的变化只在kz=0和kz=0.5平面之间沿着c轴方向出现。B原子取代C原子使价带和导带分别分裂为两个和三个能带。对Ne原子的吸附使价带能量沿着c轴方向升高并导致Fermi面附近的态密度下降。Ne原子的吸附在谷位H最稳定,顶位A其次。C-C间σ键的弯曲使Ne原子吸附在桥位b1比桥位b2处更为稳定。Ne原子在管外的吸附均为放热过程,而管内则为吸热过程。结构分析表明Ne原子对C原子有排斥作用,对B原子却具有吸引作用。B原子取代C原子的位置略凸出于CNT的管壁之外,使Ne原子的吸附能增加。 相似文献
16.
Ann Feng Dr. Wei Cheng Dr. Jennifer Holter Dr. Neil Young Prof. Dr. Richard G. Compton 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(20):6981-6986
The charging and controlled oxidative doping of single organometallic ferrocene nanoparticles is reported in aqueous sodium tetrafluoroborate using the nano‐impacts method. It is shown that ferrocene nanoparticles of approximately 105 nm diameter are essentially quantitatively oxidatively doped with the uptake of one tetrafluoroborate anion per ferrocene molecule at suitably high overpotentials. By using lower potentials, it is possible to achieve low doping levels of single nanoparticles in a controlled manner. 相似文献
17.
Dr. Christian Hering‐Junghans Max Thomas Dr. Alexander Villinger Prof. Dr. Axel Schulz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(18):6713-6717
This work describes the synthesis and full characterization of elusive chloropnictenium ion salts of the type [RAr*N(SiMe)ECl][A] (RAr*=2,6‐(CHPh2)‐4‐R‐C6H2, R=Me, tBu; E=Sb, Bi; A?=GaCl4, Al(OCH(CF3)2)4). In these species the cation is significantly stabilized by weak arene interactions to flanking phenyl groups of the RAr* moiety. In this context the bonding situation has been studied by computational means and the reactivity towards the Lewis base 4‐dimethylaminopyridine (dmap) was investigated. 相似文献
18.
Inside Back Cover: Alkaline Earth Metal Zirconate Perovskites MZrO3 (M=Ba2+, Sr2+, Ca2+) Derived from Molecular Precursors and Doped with Eu3+ Ions (Chem. Eur. J. 14/2016) 下载免费PDF全文
19.
Formation of Long,Multicenter π‐[TCNE]22− Dimers in Solution: Solvation and Stability Assessed through Molecular Dynamics Simulations
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Dr. Marçal Capdevila‐Cortada Dr. Jordi Ribas‐Arino Dr. Alain Chaumont Prof. Georges Wipff Prof. Juan J. Novoa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(47):17037-17046
Purely organic radical ions dimerize in solution at low temperature, forming long, multicenter bonds, despite the metastability of the isolated dimers. Here, we present the first computational study of these π‐dimers in solution, with explicit consideration of solvent molecules and finite temperature effects. By means of force‐field and ab initio molecular dynamics and free energy simulations, the structure and stability of π‐[TCNE]22? (TCNE=tetracyanoethylene) dimers in dichloromethane have been evaluated. Although the dimers dissociate at room temperature, they are stable at 175 K and their structure is similar to the one in the solid state, with a cofacial arrangement of the radicals at an interplanar separation of approximately 3.0 Å. The π‐[TCNE]22? dimers form dissociated ion pairs with the NBu4+ counterions, and their first solvation shell comprises approximately 20 CH2Cl2 molecules. Among them, the eight molecules distributed along the equatorial plane of the dimer play a key role in stabilizing the dimer through bridging C?H???N contacts. The calculated free energy of dimerization of TCNE . ? in solution at 175 K is ?5.5 kcal mol?1. These results provide the first quantitative model describing the pairing of radical ions in solution, and demonstrate the key role of solvation forces on the dimerization process. 相似文献
20.
Dr. Jingjun Hao Prof. Arnold L. Rheingold Marzieh Kavand Dr. Kipp J. van Schooten Prof. Christoph Boehme Dr. Marçal Capdevila‐Cortada Prof. Juan J. Novoa Eva Wöss Prof. Günther Knör Prof. Joel S. Miller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(35):12312-12315
The reaction of 2,3,5,6‐tetracyanopyridine (TCNPy) and Cr(C6H6)2 forms diamagnetic σ‐[TCNPy]22? possessing a 1.572(3) Å intrafragment sp3–sp3 bond. This is in contrast to the structurally related 1,2,4,5‐tetracyanobenzene and 1,2,4,5‐tetracyanopyrazine that form π‐dimer dianions possessing long, multicenter bonds. 相似文献