Two new antenna polyelectrolytes, poly(sodium styrenesulfonate-co-N-vinylcarbazole) (PSSS–VCz) and poly[sodium styrenesulfonate-co-N-(acryloyloxyhexyl)carbazole](PSSS–AHCz) have been synthesized. Both polymers were found to solubilize large hydrophobic compounds such as perylene in aqueous solution, but PSSS–AHCz was much more efficient than PSSS–VCz. The distribution coefficients of perylene between the polymer pseudophase and water was determined to be (2.9 ± 0.1) × 106 and (4.0 ± 0.2) × 104 in PSSS–AHCz and PSSS–VCz, respectively. The greater solubilizing ability of PSSS–AHCz is attributed to the higher content of hydrophobic monomer units in the polymer. Both copolymers displayed photocatalytic activity, absorbing light in the UV-visible spectral region. Energy can then be transferred to a solubilized molecule or dissolved oxygen and induce photochemical reactions. The model reaction used in this study was the photosensitized oxidation of perylene solubilized in aqueous polymer solutions. PSSS–AHCz was found to be a much more efficient photocatalyst than PSSS–VCz. The enhanced photocatalytic activity of PSSS–AHCz is attributed to the greater concentration of carbazole chromophores, the higher local concentration of probe in the polymeric pseudophase and possibly to the elimination of the low-energy excimer. 相似文献
The infinite coordination polymerization…? of metal ions and multitopic organic ligands is explored to fabricate metal–organic micro‐ and nanospheres that can be used as functional matrices. In their Communication on page 2325 ff., D. Maspoch and co‐workers show how this simple process affords spheres that encapsulate active substances, such as magnetic nanoparticles, organic dyes, and quantum dots, to result in multifunctional spheres. Marianne Verdoux is thanked for the cover graphic design.
A reaction–diffusion system describing the electrolyte diode is investigated. This consists of a chemically crosslinked polyvinylalcohol (PVA) hydrogel cylinder in which a pH gradient is provided by having an acid and a base maintained at constant concentrations in reservoirs at each end of the one-dimensional reactor. A potential difference of a given strength is also applied across the gel cylinder. Previous experimental studies of the current–voltage characteristics (CVC) have shown two distinct cases, depending on whether a positive or negative potential difference was applied. The slopes of the linear current–voltage response curve are substantially different in the two cases, that in the 'forward' case being typically several orders of magnitude greater than that in the 'backward' case. Thus the system behaves like a semiconductor diode. The stationary concentration distribution for the different ions is described by a system of reaction–diffusion equations involving migration caused by the electric field. An approximate solution of these equations, using a simplified model, is presented and compared with results obtained by solving the full system numerically. The concentration profiles obtained from the numerical solution confirm the validity of the simplified model. 相似文献
Structure and vibrational frequencies of lawsoneoxime and its C3-substituted (R=CH3, NH2, Cl, NO2) derivatives in keto and nitrosophenol forms have been obtained employing the Hartree–Fock and density functional methods. Charge distributions in different conformers have been studied using the molecular electrostatic potential topography as a tool. For all these derivatives except for nitrolawsoneoxime the amphi conformer in the keto form is predicted to be of lowest energy, which can partly be attributed to hydrogen bonding through the oximino nitrogen. In the nitro derivative, however, the preference to form a six membered ring owing to O–H–O hydrogen-bonded interactions makes the anti conformer (keto) the stablest. Further one of the nitrosophenol conformers of nitrolawsoneoxime turns out to be very close in energy (0.21 kJ mol–1 higher) to this anti conformer. The consequences of hydrogen bonding on charge distribution and vibrational spectra are discussed. 相似文献
The ground state of TiC is 3+, as predicted by previous configuration interaction calculations. It is shown that there are two low-lying 1+ states and that the density functional theory solution corresponds to the higher of the two 1+ states.Contribution to the Björn Roos Honorary Issue 相似文献