Anion-Regulated Hierarchical Self-Assembly and Chiral Induction of Metallo-Tetrahedra

The precise control over hierarchical self-assembly of superstructures relying on the elaboration of multiple noncovalent interactions between basic building blocks is both elusive and highly desirable. We herein report a terpyridine-based metallo-cage T with a tetrahedral motif and utilized it as an efficient building block for the controlled hierarchical self-assembly of superstructures in response to different halide ions. Initially, the hierarchical superstructure of metallo-cage T adopted a hexagonal close-packed structure. By adding Cl⁻/Br⁻ or I⁻, drastically different hierarchical superstructures with highly-tight hexagonal packing or graphite-like packing arrangements, respectively, have been achieved. These unusual halide-ion-triggered hierarchical structural changes resulted in quite distinct intermolecular channels, which provided new insights into the mechanism of three-dimensional supramolecular aggregation and crystal growth based on macromolecular construction. In addition, the chiral induction of the metallo-cage T can be realized with the addition of chiral anions, which stereoselectively generated either PPPP- or MMMM-type enantiomers.     

钴萃取研究 Ⅸ.有机磷(膦)酸萃取剂结构与萃取分离钴(Ⅱ)、镍(Ⅱ)性能的研究

本文就三种典型的有机磷(膦)酸萃取剂P_(204)、P_(507)、P_(272)在高氯酸盐体系中对Co(Ⅱ)、Ni(Ⅱ)萃取分离能力进行了比较。 在萃取体系有机相中,上述三种萃取剂与Co(Ⅱ)形成的萃合物均存在粉红色八面体与蓝色四面体构型转化的平衡反应。随着萃取剂分子中氧烷基被烷基取代,反应基团磷氧酰基氧原子上电子云密度增加,酸性降低,与Co(Ⅱ)形成的四面体萃合物稳定性增强,对Co(Ⅱ)/Ni(Ⅱ)分离的能力增加。Co(Ⅱ)四面体萃合物的稳定性是影响Co(Ⅱ)/Ni(Ⅱ)分离效果最主要的因素。这一结论还可通过Co(Ⅱ)/Ni(Ⅱ)萃取分离温度效应与Co(Ⅱ)萃合物构型转化温度效应的一致性得到证实。在所研究的三类有机磷(膦)酸萃取剂结构因素中,磷氧酰基氧原子上的电子云密度是影响Co(Ⅱ)/Ni(Ⅱ)分离效果的关键因素。     

Molecular hexagram and octagram: Position determined 3D metallo-supermolecules and concentration-induced transformation

The reaction of a metallo-organic ligand(LA) in which two V-shaped bisterpyridines attaching to metaposition of X-shaped tetraterpyridine via tpy-Ru~(2+)-tpy connectivity and Zn~(2+)ions gave rise to 3D supramolecular architectures:octagram(Zn_8 LA_4).However,a position varied ligand(LB) in which two V-shaped bisterpyridines locating at the ortho-position of X-shaped tetraterpyridine afforded a different 3D hexagram(Zn_6LB_3).Full characterizations included NMR(~1 H,~(13)C,2 D COSY,NOESY and DOSY),ESI-MS,TWIM-MS,TEM and AFM.The resulted structures were directly determined by the position of two V-shaped bisterpyridines attaching to X-shaped tetraterpyridine.     

Influence of the methyl group at C=C bridging bond of stilbene on the longest wavelength maximum in ultraviolet absorption spectra

The compounds stilbenes XArCH=CHArY(XSBY) and 1,2‐diphenylpropylenes XArC(Me)=CHArY(XSMBY) have bridging groups CH=CH and C(CH₃)=CH, respectively, in which the C(CH₃)=CH has a side‐group CH₃ at the carbon‐carbon double bond. A series of XSMBY were synthesized, and their longest wavelength maximum λ_max (nm) in ultraviolet absorption spectra were measured in this work. We investigated the change regularity of the ν_max (cm^‐1, ν_max = 1/λ_max) of XSMBY and compared it with that of XSBY. The results indicate that (1) there is no good linear relationship between the ν_max of XSMBY and that of XSBY. (2) Because of the influence of the side‐group CH₃, in case of the same couple of groups X and Y, the λ_max of XSMBY is shorter than that of XSBY, that is, it has a blue shift. (3) The cross‐interaction between the side‐group CH₃ and Y has an important effect on the ν_max of XSMBY, while the cross‐interaction between the side‐group CH₃ and X has a little effect on the ν_max and can be ignored. (4) The specific cross‐interaction between X and Y has important effect on the ν_max of XSMBY, whereas it has no important effect on the ν_max of XSBY.     

Characterization of the Binding of Metoprolol Tartrate and Guaifenesin Drugs to Human Serum Albumin and Human Hemoglobin Proteins by Fluorescence and Circular Dichroism Spectroscopy

The interactions of metoprolol tartrate (MPT) and guaifenesin (GF) drugs with human serum albumin (HSA) and human hemoglobin (HMG) proteins at pH?7.4 were studied by fluorescence and circular dichroism (CD) spectroscopy. Drugs quenched the fluorescence spectra of HSA and HMG proteins through a static quenching mechanism. For each protein-drug system, the values of Stern-Volmer quenching constant, bimolecular quenching constant, binding constant and number of binding site on the protein molecules were determined at 288.15, 298.15, 310.15 and 318.15 K. It was found that the binding constants of HSA-MPT and HSA-GF systems were smaller than those of HMG-MPT and HMG-GF systems. For both drugs, the affinity of HMG was much higher than that of HSA. An increase in temperature caused a negative effect on the binding reactions. The number of binding site on blood proteins for MPT and GF drugs was approximately one. Thermodynamic parameters showed that MPT interacted with HSA through electrostatic attraction forces. However, hydrogen bonds and van der Waals forces were the main interaction forces in the formation of HSA-GF, HMG-MPT and HMG-GF complexes. The binding processes between protein and drug molecules were exothermic and spontaneous owing to negative ?H and ?G values, respectively. The values of binding distance between protein and drug molecules were calculated from Förster resonance energy transfer theory. It was found from CD analysis that the bindings of MPT and GF drugs to HSA and HMG proteins altered the secondary structure of HSA and HMG proteins.     

The crystal-field dependency of sound attenuation in the spin-3/2 ising model

The effects of crystal-field (D) on sound attenuation are considered for the spin-3/2 Ising model by using Onsager theory of irreversible thermodynamics. It is assumed that the sound wave couples to the order-parameter fluctuations, therefore, it decays mainly via order-parameter relaxation process. The order-parameters, magnetization and quadrupole moment, are defined in terms of exact recursion relations (ERR) on Bethe lattice (BL). After our analysis, two relaxation times are obtained and they are used to calculate the sound attenuation coefficient (α). Consequently, the critical behaviors of sound attenuation coefficient are investigated in terms of frequency (w) and Onsager coefficient (γ) for the coordination numbers q=3, 4 ad 6 near the second-order (T_c) and first-order (T_t) phase transition temperatures in the ferromagnetic phase regions for the negative and positive D values and the results are presented on the (k_BT/J, α) planes. It is found that the peaks about T_t’s are observed at the same temperature, but the peaks about T_c’s are observed shifted to lower and higher temperatures in increasing (w)’s and (γ)’s, respectively. In addition, the peaks are also obtained near the tricritical points for all q.     

Some INDO calculations of fluorine-nitrogen spin–spin coupling constants

INDO parameterized calculations of ⁿJ(¹⁹F¹⁵N) are reported where n=1, 2, 3, 4 and 5. The calculations are performed within the sum-over-states perturbation and self-consistent perturbation frameworks. In general, satisfactory agreement between both sets of calculated results and the available experimental data is obtained. All of the ¹ J(¹⁹F¹⁵N) and ⁴J(¹⁹F¹⁵N) couplings can be of either sign. Most of the couplings considered are dominated by the contact contribution but the non-contact interactions can be very important in certain cases.     

Stability to vector Liénard equation with constant deviating argument

In this paper, we consider the vector Liénard equation with the constant deviating argument, τ>0, $$X''(t) + F\bigl(X(t),X'(t) \bigr)X'(t) + H\bigl(X(t - \tau)\bigr) = P(t) $$ in two cases: (i) P(.)≡0, (ii) P(.)≠0. Based on the Lyapunov–Krasovskii functional approach, the asymptotic stability of the zero solution and the boundedness of all solutions are discussed for these cases. We give an example to illustrate the theoretical analysis made in this work and to show the effectiveness of the method utilized here.