A series of oxidized di(indolyl)arylmethanes (DIAM) with polyaromatic signaling moieties have been designed for monitoring local pH at the interfacial region of surfactant aggregates, such as micelles and vesicles. The oxidized DIAMs show changes in solution color from red to yellow when incorporated in cationic surfactants (at pH 7.4) and yellow to reddish pink when exposed to negatively-charged surfactants (at pH 5.0). The changes in surface charge can influence the interfacial pH (distinct from bulk pH of the medium) of the surfactant aggregates. The mechanistic studies indicate that the red-shifted absorption maxima observed in the presence of anionic amphiphiles (acidic local pH) originated from the protonated species. On the contrary, maxima in the blue region, triggered by positively charged amphiphiles (basic local pH), is attributed to the zwitterionic species. Such prototropic equilibrium affects charge transfer states of the molecules along with their self-assembly properties. Thus, it is evident that probes can predict as well as quantify the local pH change using the pseudophase ion exchange formalism. Also, the probes can detect the presence of anionic amphiphiles even when bound to phospholipid membranes. 相似文献
Structural Chemistry - Malaria infection continues to pose a substantial threat to human health in the twenty-first century. The parasites’ resistance against conventional antimalarial drugs... 相似文献
Epindolidione (H2L), a heteroatom-modified analogue of tetracene and a structural isomer of indigo, forms dinuclear complexes with [RuX2]2+, X=bpy (2,2′-bipyridine, [ 1 ]2+) or pap (2-phenylazopyridine, [ 2 ]2+), in its doubly deprotonated bridging form μ-L2−. The dications in compounds meso-[ 1 ](ClO4)2 and meso-[ 2 ](ClO4)2, [X2Ru(μ-L)RuX2](ClO4)2, contain five-membered chelate rings N-C−C-O-RuII with π bridged metals at an intramolecular distance of 7.19 Å. Stepwise reversible oxidation and reduction is mainly ligand centered (oxidation: L2−; reduction: X), as deduced from EPR of one-electron oxidized and reduced intermediates and from UV/Vis/NIR spectroelectrochemistry, supported by TD-DFT calculation results. The results for [ 1 ](ClO4)2 and [ 2 ](ClO4)2 are qualitatively similar to the ones observed with the deprotonated indigo-bridged isomers with their six-membered chelate ring structures, confirming the suitability of both π systems for molecular electronics applications, low-energy absorptions, and multiple electron transfers. 相似文献
Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes with a potentially tridentate Schiff base, formed by condensation of 2-amino-3-carboxyethyl-4,5-dimethylthiophene with salicylaldehyde were synthesized and characterized on the basis of elemental analyses, molar conductance values, magnetic susceptibility measurements, UV-vis, IR, EPR and NMR spectral data, wherever possible and applicable. Spectral studies reveal that the free ligand exists in a bifunctionally hydrogen bonded manner and coordinates to the metal ion in a tridentate fashion through the deprotonated phenolate oxygen, azomethine nitrogen and ester carbonyl group. On the basis of electronic spectral data and magnetic susceptibility measurements, suitable geometry has been proposed for each complex. The EPR spectral data of the Cu(II) complex showed that the metal-ligand bonds have considerable covalent character. The Ni(II) complex has undergone facile transesterification reaction when refluxed in methanol for a lengthy period. X-ray diffraction studies of Cu(II) complex showed that the complex has an orthorhombic crystal lattice. In view of the biological activity of thiophene derivatives, the ligand and the complexes were subjected to antibacterial screening. It has been observed that the antibacterial activity of the ligand increased on chelation with metal ion. 相似文献
The effects of “pre-adsorbed cations” in photoanodes on the performances of dye-sensitized solar cells (DSSCs) were studied using two different size cations (K+ and guanidine cation (G+)). While the DSSCs with optimized K+ ions pre-adsorbed photoanodes showed a maximum efficiency of 7.04%, the DSSCs with G+ ions pre-adsorbed photoanodes showed an efficiency of 6.73%. DSSCs fabricated with conventional photanodes (without pre-cation adsorption) showed an efficiency of 6.21%. Differences in efficiencies are very likely due to the cation pre-adsorption effects and could be due to a higher number of K+ cation adsorption per unit area of TiO2 surface of the photoanode compared to a smaller number of G+ cation adsorption in TiO2, due to their difference in sizes. This pre-cation adsorption technique can be used to improve the overall efficiency of a DSSC by about 14% fold over the conventional photoanodes use in DSSCs, specially using smaller cations.
Carbon nanodots (CNDs) are a developing branch of nanomaterials and nanoscience. This has generated much more interest in the field and class of biomedicine science by way of unique particular properties, such as high stability, great photoluminescence, easy green synthesis, and simple surface modification. Numerous applications, such as bioimaging, biosensing, and treatment, have made use of CNDs. This review describes the most recent developments in CND research and talks about major changes in the understanding of CNDs and their prospects as biomedical tools. The importance of this work lies in the ability of CNDs to overcome many of the limitations associated with traditional materials used in biomedicine, such as toxicity, poor biocompatibility, and limited functionality. Furthermore, the use of CNDs as drug carriers, imaging agents, and sensors has shown great potential in improving the diagnosis and treatment of various diseases. The novelty of this work lies in the diversity of approaches used in the synthesis and functionalization of CNDs, and the unique properties of CNDs that make them versatile tools for biomedicine. In particular, the ability to tune the size, shape, and surface chemistry of CNDs allows for the creation of tailored materials with specific biomedical applications. The review also discusses the challenges and future prospects of CNDs in biomedicine, including the need for standardization and optimization of CND synthesis, functionalization, and characterization protocols. 相似文献
A dynamic problem of an infinite isotropic cylinder of radius r subjected to boundary conditions of the radial stress, temperature, or concentration of the diffusing substance is studied by using the equations of state of a elastothermodiffusive solid with one relaxation time and the Laplace transform technique. The distributions of the displacement, temperature, and concentration are displayed graphically and analytically. 相似文献
Tin diselenide single crystals have been grown by the physical vapour transport (PVT) method. Optical absorption studies give an indirect allowed transition at 1.03 eV at room temperature. The electrical resistivity parallel and perpendicular to c-axis, mobility and carrier concentration have been determined. Dependence of resistivity parallel to c-axis on temperature gives an activation energy of 0.072 eV. Growth spirals observed for the first time on the as grown faces of these crystals are also presented here. 相似文献