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151.
Structure of microemulsions with gemini surfactant studied by solvatochromic probe and diffusion NMR
Ben Moshe M Magdassi S Cohen Y Avram L 《Journal of colloid and interface science》2004,276(1):221-226
The structure of microemulsions prepared by the anionic gemini surfactant didodecyl diphenyl ether disulfonate (C12-DADS) was investigated by a solvatochromic probe and nuclear magnetic resonance (NMR) diffusion measurements. The NMR measurements indicate the presence of bicontinuous and oil-in-water microemulsions depending on microemulsion composition. The absorbance spectra of the solvatochromic probe, Nile red, indicate the solubilization of the probe in different sites, in agreement with the NMR findings. It was also found that the microemulsions were capable of dissolving the hydrophobic probe, Nile red, up to four times better than expected if it were simply dissolved in the toluene phase. 相似文献
152.
“Aromatic nucleophilic substitution-rearrangement (SNAr-rearrangement)” mechanism provided a powerful tool to design fluorescent probes for the discrimination between biothiols. 相似文献
153.
Yiru Zhang Jianlei Shen Rong Hu Xiujuan Shi Xianglong Hu Benzhao He Anjun Qin Ben Zhong Tang 《Chemical science》2020,11(15):3931
Surface immobilization provides a useful platform for biosensing, drug screening, tissue engineering and other chemical and biological applications. However, some of the used reactions are inefficient and/or complicated, limiting their applications in immobilization. Herein, we use a spontaneous and catalyst-free amino-yne click bioconjugation to generate activated ethynyl group functionalized surfaces for fast immobilization of native proteins and cells. Biomolecules, such as bovine serum albumin (BSA), human IgG and a peptide of C(RGDfK), could be covalently immobilized on the surfaces in as short as 30 min. Notably, the bioactivity of the anchored biomolecules remains intact, which is verified by efficiently capturing target antibodies and cells from the bulk solutions. This strategy represents an alternative for highly efficient surface biofunctionalization.Fast surface immobilization of native bioconjugates through a spontaneous amino-yne click reaction is realized. 相似文献
154.
The ability of templated uranium sulfate fluorides to adopt diverse inorganic architectures is demonstrated in six novel materials. The inorganic structures present in [N2C6H16][UO2F2(SO4)](USFO-2), [N2C6H16][UO2F(SO4)]2(USFO-3), [N2C3H12][UO2F(SO4)]2.H2O (USFO-4), [N2C5H14][UO2F(H2O)(SO4]2(USFO-5), [N2C6H18]2[UO2F(SO4)]4.H2O (USFO-6) and [N2C3H12][UO2F(SO4)]2.H2O (USFO-7) range from infinite chains to five different layer topologies. The chain, and two of the five layers, have unprecedented structure types. These compounds illustrate the structural diversity within this new family of materials, arising from the varied coordination of the U6+ centres. Each material was synthesised under hydrothermal conditions, through reaction of uranyl acetate, sulfuric acid, HF(aq), water, and the respective organic template. 相似文献
155.
T. Nakamura S. Kojima T. Ohta M. Nishida A. Rakowski A. Ikeda H. Oda E. Niu 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(2):327-332
14C variations of atmospheric CO2 as well as carbonaceous fraction of living materials, such as collagen from tooth and bone, tissue, skin, hair, nail, etc.,
of modern humans are influenced by 14C produced artificially by nuclear bomb tests in the atmosphere from late 1950s to early 1960s. By careful investigation of
14C concentration of tree rings and human body samples formed in this time intervals, we can establish a relationship of their
14C concentrations with calendar year. By applying this relation to a sample whose 14C concentration can be measured, we can estimate the formation age of the sample. In addition, sources of the chemicals that
were used in some criminal cases can be possibly identified, by their carbon isotope ratios (13C/12C and 14C/12C). This method of age determination has been applied to a forensic study, i.e., two criminal cases of murder. For each case,
by comparing the measured 14C abundances of several pieces of hair and one tooth (the third molar) from the body with the annual change on concentrations
of bomb-produced 14C, the time of death of the body and the age of the victim were estimated. The estimated values were consistent with the real
ones that were revealed by the confession of the real murderers. 相似文献
156.
Three novel Schiff base cadmium(II) complexes, derived from the end‐on (μ‐1,1‐N3) azide or end‐to‐end (μ‐1,3‐NCS) thio cyanate bridges and similar tridentate Schiff base ligands, have been synthesized under similar synthetic procedures and their crystal structures determined by X‐ray diffraction methods. They are the dinuclear double end‐on azide‐bridged [Cd2(L1)2(N3)2(μ‐1,1‐N3)2] ( 1 ), the dinuclear double end‐on azide‐bridged [Cd2(L2)2(N3)2(μ‐1,1‐N3)2] ( 2 ), and the dinuclear double end‐to‐end thiocyanate‐bridged [Cd2(L3)2(NCS)2(μ1,3‐NCS)2] ( 3 ), where L1, L2 and L3 are three similar tridentate Schiff bases obtained by condensation of 2‐pyridylaldehyde with N,N‐diethylethane‐1,2‐diamine, of 2‐pyridylaldehyde with N‐isopropylethane‐1,2‐diamine, and of 2‐pyridylaldehyde with N,N‐dimethylpropane‐1,3‐diamine, respectively. Each cadmium(II) centre in the complexes is in a distorted octahedral coordination. There is a crystallographic inversion centre in each of the complexes. The similar small ligands used as the secondary ligands in the preparation of the cadmium(II) complexes with similar Schiff bases can result in similar structures. 相似文献
157.
Foldable polymers with alternating single-strand deoxyribonucleic acid and planar conjugated organic perylene tetracarboxylic diimide units were found to self-organize into loosely folded nanostructures. Upon heating, the loosely folded structures become more ordered as evidenced by pi-stacking in the perylene segments. The folding and unfolding processes driven by the molecular interactions of adjacent perylenes were monitored in both aqueous and organic solutions. Heat-promoted folding, or inverse temperature behavior, which originates from positive enthalpy changes, was only observed in water. Therefore, we attributed this inverse temperature dependence to hydrophobic effects rather than pi-pi molecular orbital overlap between the perylene planes. These findings shed light on the design of new thermophiles in protein engineering as well as the construction of macromolecular-based nanodevices with actuator and sensory properties. 相似文献
158.
Zhai HJ Yang X Wang XB Wang LS Elliott B Boldyrev AI 《Journal of the American Chemical Society》2002,124(23):6742-6750
Although neutral and ionic O4(0/-/+) species have been observed experimentally and considered for energetic materials, O4(2-) and O5(2-) dianions have not yet been explored. O4(2-) is valent isoelectronic to the well-known ClO3- and SO3(2-) anions, and O5(2-) is valent isoelectronic to ClO4- and SO4(2-). All are stable, common anions in solutions and inorganic salts. In this article, we explore the possibility of making covalently bound O4(2-) and O5(2-) species stabilized in the forms of M+O4(2-) and M+O5(2-) (M = Li, Na, K, Cs) in the gas phase. Laser vaporization experiments using M-containing targets and an O2-seeded carrier gas yielded very intense mass peaks corresponding to MO4- and MO5-. To elucidate the structure and bonding of the newly observed MO4- and MO5- species, we measured their photoelectron spectra and then compared them with ab initio calculations and the spectra of ClO3-, Na+SO3(2-), ClO4-, and Na+SO4(2-). Careful analyses of the experimental and ab initio results showed, however, that the observed species are of the forms, O2-M+O2- and O2-M+O3-. The more interesting M+O4(2-) and M+O5(2-) species were found to be higher-energy isomers, but they are true minima on the potential energy surfaces, which suggests that it might be possible to synthesize bulk materials containing covalently bound tetra- and pentatomic oxygen building blocks. 相似文献
159.
本文研究了乙酰基香豆素及其衍生物与吲哚的混晶在微环境影响下的固相光反应,并用固体紫外光谱、固体荧光光谱和X-射线粉末衍射技术考察了混晶的特征。实验结果表明,3-乙酰基香豆素及其7-乙酰氧基、7-苯甲酰氧基、5,6-苯并和6-溴衍生物与吲哚的固相光反应分别得到1:2缩合产物1~5,而6-硝基衍生物与吲哚的固相光反应却得到开环脱羰加成产物6。通过IR、MS、^1H NMR和元素分析结果确定了这六个新产物的结构。固体光谱的测试结果表明,取代乙酰基香豆素与吲哚间混晶的形成,分子间存在相互作用,使分子所处的微环境条件发生了变化。 相似文献
160.
Three hexakis(imidazole)metallo complexes of Co, Cd and Ni were synthesized and spectroscopically characterized. The crystal and molecular structures have been determined by X-ray crystallography analysis. The metal ions have an octahedral geometry with the MN6 chromophore. The electrochemical experimental results indicate that both [Co(Im)6]C12·2HCl·2H2O (1) and [Ni(Im)6]C12·4H2O (3) [Im=imidazole] could interact with DNA mainly by intercalation. 相似文献