Structures, conformations, and crystallization behavior of compounds cis--[Co(trien)(NO2)2]·ClO4 (I), cis--[Co(trien)(NO2)2]Br·2H2O (II), and cis--[Co(trien)(NO2)2]·ClO3 (III) are reported. Compound (I) crystallized in space group Pbca, with a = 12.3323(9), b = 13.0265(9) and c = 18.1597(13) Å; compound (II) crystallized in space group Pca21, with a = 8.1844(7), b = 14.7011(14) and c = 12.4875(12) Å, while compound (III) also crystallized in space group Pca21, with a = 12.4897(8), b = 8.8499(6) and c = 12.6500(8) Å. In all three cases, the Co(III) ions were six-coordinated with nitrogens from trien and two nitrates. Inter- and intramolecular hydrogen bonding interactions are discussed to explain the conglomerate versus racemate crystallization behavior adopted by these three compounds, with comparison of their known analogue compounds of cis-/-[Co(trien)(NO2)2]X, where X = halide and NO–3. For the cis--[Co(trien)(NO2)2]+ cation, the conformation of the cation itself determines the intramolecular hydrogen bonding pattern, and the interaction of counteranions can be ignored, while in cis--[Co(trien)(NO2)2]·ClO4, the perchlorate interrupts the intramolecular hydrogen bonding pattern observed in the halide analog. 相似文献
The conformational transition of a single bottle‐brush polyelectrolyte with charged and neutral side chains is studied through MD simulations. Counterions are included explicitly and no additional salt is added. The structure of the polyelectrolyte and the counterion condensation are found to depend greatly on the Bjerrum length. As the Bjerrum length increases, the neutral side chains in a poor solvent can condense into clusters with variable size. Moreover, the polyelectrolyte forms globular structures at large or very small Bjerrum lengths. This transition is quite different from that in the case of a good solvent, in which there are not observable clusters and a globular structure is only formed at large Bjerrum lengths.
A novel and simple ionic liquid methodology for the synthesis of 1,5‐benzodiazepines is described. 1‐Butylpyridinium hydrogen sulphate ([BPy]HSO4), an acidic room‐temperature ionic liquid, as a novel and efficient catalyst, was synthesized and used in the preparation of a series of 1,5‐benzodiazepine derivatives by the reaction of o‐phenylenediamine with chalcones under mild conditions. This method is easy, efficient, environmentally friendly, economical, free of toxic catalysts, and has good yields for the formation of 1,5‐benzodiazepines 相似文献
The rheological behavior of alkyimethylammonium 2-hydroxy-1-carboxy-naphthoate, CxTA-2.1-HCN (x = 16, 14, 12, 10, and 8) is presented. With increasing 2.1 HNC/CxTAOH (x = 16, 14, 12) ratio, the viscoelasticity of the solutions changes due to a transition in the micellar shape from small micelles to rodlike micelles and finally to multilamellar vesicles (MLV). On the other hand, a transition from small micelles to multilamellar vesicles (MLV) was observed for solution with CxTA-2.1-HCN (x = 10 and 8). The MLV phases behave like a weak gel and have a yield stress value. Rheological measurements were performed for these viscoelastic systems in order to find out the dependency of the viscoelastic behavior on the surfactant chain length and hydrophobic counterion concentration. Some theoretical models as reptation mechanism was also applied in order to get some structural details and to illustrate the rheological behavior of these viscoelastic systems. Some models that correlate MLV-modulus on the surfactant morphology are also presented and discussed. 相似文献
The mixed micelle formation of binary cationic 14-s-14 gemini with conventional single chain surfactants was studied by conductivity measurements.The critical micelle concentration(cmc) and the degree of counterion binding values(g) of the binary systems were determined.The results were analyzed by applying regular solution theory(RST) to calculate micellar compositions(X),activity coefficients(f1,f2),and the interaction parameters(β).The synergistic interactions of all the investigated cationic gemini+conventional surfactant combinations were found to be dependent upon the length of hydrophobic spacer of the gemini surfactant.The excess Gibbs free energy of mixing was evaluated,and it indicated relatively more stable mixed micelles for the binary combinations. 相似文献