手性锌卟啉对咪唑类客体分子识别的构象研究

Chiral recognition is an attractive subject in the area of host-guest chemistry. Conformation study is performed to understand chiral recognition of zinc(Ⅱ) porphyrin with imidazole derivatives on a molecular level. The molecular recognition of three novel chiral zinc porphyrin(1-3) with four types of imidazole derivatives was studied. The conformation searching of this host-guest system was studied by using simulated annealing method on the basis of Tripos force field. The different minimal energy conformation of imidazole combind with porphyrin was studied. The quantum chemistry calculation was performed to calculate the single-point energies of the host-guest system. The minimal energy conformation of ZnT(o-BocAla)APP (3)-Im showed that Im attaching from the single-side chain of the host had the reasonable configuration than that from the three-side chain. The former also had the lower energy than the latter. And the quantum chemistry calculation results of orbital energy, ΔE_L-H, and atomic net charge revealed the same way. The results illumate that combination oriention of the host-guest system is the single chain of the hosts.     

超分子砌块间苯二酚杯芳烃的研究进展

间苯二酚杯芳烃是一类以间苯二酚为单元的杯芳烃, 作为新一代超分子砌块, 在分子催化、分子识别、超分子自组装、晶体工程和纳米材料等方面都获得了广泛的应用, 已成为当今化学研究的新热点. 综述了间苯二酚杯芳烃的功能化修饰及其应用新进展.     

Dissipative structures formed in the course of drying the colloidal crystals of silica spheres on a cover glass

Macroscopic and microscopic dissipative structural patterns formed in the course of drying the deionized aqueous colloidal crystal suspensions of silica spheres (diameter: 103 nm) on a cover glass have been observed. Spoke-like and ring-like patterns are formed in the macroscopic scale; the former is the crack in the sphere film and the latter is the hill accumulated with spheres formed around the outside edge. The neighbored inter-spoke angle, thickness of the film, and other morphological parameters have been discussed as a function of sphere concentration, concentration of sodium chloride, and the inclined angle of the cover glass. Fractal patterns of the mud cracks are observed in the microscopic scale. Capillary forces between spheres at the air-liquid surface and the relative rates between the water flow at the drying front and the convection flow of spheres are important for the pattern formation. Electronic Publication     

Water-soluble aminocalix[4]arene receptors with hydrophobic and hydrophilic mouths

We report the new water-soluble aminocalix[4]arene hosts 1 and 2 with deep hydrophobic cavity facilitating hydrophobic mouth and hydrophilic mouth, respectively. The ¹H NMR titrations revealed that host 1 shows high selectivity for neutral guests 9 and 10, with log K of 4.2 and 4.6, respectively. The host 2 shows log K of 4.9 for binding with guest 15. Moreover, the binding ability of the host 2 for guest 14 is stronger by a factor of 1000 than that of the host 1.     

Addressing association entropy by reconstructing guanidinium anchor groups for anion binding: design, synthesis, and host-guest binding studies in polar and protic solutions

The bicyclic hexahydropyrimidino[1,2a]pyrimidine cationic scaffold has a well-known capacity to bind a variety of oxoanions (phosphates, carboxylates, squarates, phosphinates). Based on this feature, the parent host was supplemented with sec-carboxamido substituents to generate compounds 1-3 in an effort to improve the anion-binding affinity and selectivity and to learn about the role and magnitude of entropic factors. Bicyclic guanidinium compounds were prepared by a convergent strategy via the corresponding tetraester 22 followed by catalytic amidation. Host-guest binding studies with isothermal titration calorimetry in acetonitrile probed the behavior of artificial hosts 1-3 in comparison with the tetraallylguanidinium compound 4 on binding p-nitrobenzoate, dihydrogenphosphate, and 2,2'-bisphenolcyclophosphate guests that showed enhanced affinities in the 10(5)-10(6) M(-1) range. Contrary to expectation, better binding emerges from more positive association entropies rather than from stronger enthalpic interactions (hydrogen bonding). In an NMR spectroscopy titration in DMSO, o-phthalate was sufficiently basic to abstract a proton from the guanidinium function, as confirmed by an X-ray crystal structure of the product. The novel carboxamide-appended anchor groups also bind carboxylates and phosphates, but not hydrogen sulfate in methanol with affinities in excess of 10(4) M(-1). The energetic signature of the complexation in methanol is inverted with respect to acetonitrile solvent and shows a pattern of general ion pairing with strong positive entropies overcompensating endothermic binding enthalpies. This study provides an example of the fact that bona fide decoration of a parent guanidinium anchor function with an additional binding functionality may provide the desired enhancement of the host-guest affinity, yet for a different reason than that implemented by design as guided by standard molecular modeling.     

Ferrocene incorporating host-guest dyads with electrochemically controlled three-pole hydrogen bonding properties

We describe the electrochemically controlled hydrogen bonding interactions between the isobutyl flavin/2,6-diferrocenylamidopyridine (2·5) and 9,10-phenanthrenequinone/1-ferrocenyl-3-hexylurea (4·6) dyads. Cyclic and square wave voltammetry studies have shown that the binding efficiencies between these moieties can be electrochemically actuated in non-polar (CH₂Cl₂ for 2·5) or polar (DMF for 4·6) organic solvents between three distinct states.     

A Hybrid DNA Aptamer–Dendrimer Nanomaterial for Targeted Cell Labeling

Antibodies are natural nanomaterials and have been widely used for targeted cell labeling. However, the applications of antibodies are often limited by their large size and instability. The purpose of this study is to develop a new type of multifunctional nanomaterial that is comprised of a nucleic acid aptamer and a dendrimer, both of which are stable. This nanomaterial is ≈8 nm in size. Moreover, it could not only carry multiple signal molecules, but also bind to target cancer cells with high affinity and specificity. This sub‐10 nm multifunctional nanomaterial is expected to be useful in basic biomedical research and clinical medicine.

     

Use of enriched <Superscript>74</Superscript>Se and <Superscript>77</Superscript>Se in combination with isotope pattern deconvolution to differentiate and determine endogenous and supplemented selenium in lactating rats

A quantitative methodology has been developed to differentiate between endogenous and supplemented selenium in lactating rats using two enriched selenium isotopes. Lactating rats were fed for 2 weeks with formula milk containing one enriched Se isotope, ⁷⁷Se, as the metabolic tracer. The isotopic composition of selenium in serum and urine samples was then measured by collision cell ICP-MS after the addition of a solution containing another enriched isotope, ⁷⁴Se, as quantitation tracer, before analysis. Isotope pattern deconvolution allowed the transformation of measured Se isotopic abundances into concentrations of natural abundance (endogenous) selenium and enriched ⁷⁷Se (supplemented) present in the samples. The proposed methodology was validated using serum and urine reference materials spiked with both ⁷⁷Se and ⁷⁴Se. The obtained results are discussed in terms of selenium exchange and half-life in lactating rats (11–12 days) and selenium levels in serum in comparison with non-supplemented rats and control rats after maternal feeding.     

径向基-偏最小二乘-贝叶斯方法及其在化学模式分类中的应用

提出一种用于模式分类的RBF-PLS—Bayes方法。它集成地应用径向基(RBF)变换与偏最小二乘(PLS)方法，从原有模式中提取出分类能力甚强的成分，然后进行贝叶斯(Bayes)判别。这种集成方法尤其适用于复杂化学信息的模式分类，本文将其应用于两种类型的化学模式分类问题，均取得了令人满意的效果。与经典的判别分析方法和单纯的神经网络方法相比，具有明显的优越性。     

Molecular recognition of viologen by zinc porphyrinic receptors with diarylurea sidearms. Toward construction of a supramolecular electron transfer system

A series of zinc porphyrinic receptors for a viologen substrate (hexyl viologen, HV²⁺) were synthesized, in which varying numbers of diarylurea moieties, from one to four, were appended at the porphyrin's meso positions. The increase in the number of the diarylurea moiety led to the increase in stability of the receptor-HV²⁺ complex, showing that the convergent dipoles set up on the porphyrin platform played an essential role in the complexation. In this system, formation of the stable electron donor-acceptor complex resulted in the effective electron transfer from the singlet excited state of the zinc porphyrin to HV²⁺.