Study on the inclusion interactions of berberine hydrochloride and cucurbit[7] by spectrofluorimetry

The inclusion interaction between berberine hydrochloride （BRH） and cucurbit[7] （CB[7]） has been studied by spectrofluorimetry. The result showed that CB[7] interaction with BRH to form a stable inclusion complex with an association constant of 9.57 × 10^4 L/mol and the fluorescence intensity of the complex was enhanced in 17 times higher than that of the studied drug itself. Based on the significant enhancement of fluorescence intensity of BRH in inclusion complex, a spetrofluorimetric method with high sensitivity and selectivity was developed for the determination of BRH in aqueous solution. The linear range of the method was 3.2- 2 × 10^3 ng/mL with a detection limit of 1.1 ng/mL. The proposed procedure could be applied successfully to determination of BRH remained in pharmaceutical dosage forms, spiked human plasma and urine with satisfactory results.

Elastic interaction between inclusions and tunable periodicity of superlattice structure in nanowires

The elastic stress distribution and the variation of the elastic energy with spacing between two inclusions of arbitrary sizes in an infinite isotropic cylindrical rod are obtained by an analytical approach and the phase field microelasticity(PFM)simulation.The results show a near-attraction and far-repulsion elastic interaction between two inclusions with hydrostatic dilatation.The critical spacing,at which the interaction changes from attraction to repulsion,is on the order of the radius of the rod,dependent on the length and Poisson’s ratio of inclusions.Furthermore,the elastic energy calculations and PFM simulation results indicate that applying the local radial stress on the rod surface can modulate the elastic interaction between inclusions and adjust the periodicity of the superlattice nanowire structure.This can provide some guidelines for the tunable construction of superlattice nanowire structures.

THE CRACK-INCLUSION INTERACTION AND THE ANALYSIS OF SINGULARITY FOR THE HORIZONTAL CONTACT

Using the basic solutions of a single crack and a single inclusion, and making use of the principle of linear superposition of elastic mechanics, the interaction problem between a planar crack and a flat inclusion in an elastic solid is studied. The problem is reduced to solve a set of standard Cauchy-type singular equations. And the stress intensity factors at points of crack and inclusion were obtained. Besides, the singularity for the horizontal contact of crack and inclusion was analyzed. The calculating model put forward can be regarded as a new technique for studying the crack and its expanding caused by inclusion lip. Then several numerical examples are given.

THE INTERACTION PROBLEM BETWEEN THE ELASTIC LINE INCLUSIONS

Using the engineering model of elastic line inclusion and the basic solutions of a single inclusion, the interaction problem between line inclusions in an elastic solid it-as investigated. A set of standard Cauchy-type singular equations of the problem was presented. The stress intensity factors at points of inclusions and the interface stresses of two sides of the inclusion were calculated. Several numerical examples were given. The results could be regarded as a reference to engineering.

INTERACTION BETWEEN DISLOCATION AND TWO CIRCULAR CYLINDRICAL INCLUSIONS

The elastic field of the infinite homogeneous medium with two circular cylindrical inclusions under the action of a screw dislocation was investigated. The analytical solution was obtained using the conformal mapping and the theorem of analytical continuation. It has been shown that the elastic field depends on the shear moduli of individual phase, the geometric parameters of the system, and the position and relative slip of the screw dislocation. The specific cases, that two circular cylindrical inclusions are tangent to each other and the screw dislocation is located in inclusions, were considered. The numerical results were illustrated to show the interaction between the dislocation and two circular cylindrical inclusions. (Edited author abstract) 13 Refs.

Host-guest supramolecular interaction behavior at the interface between anode and electrolyte for long life Zn anode

The hydrogen evolution reaction (HER) and dendrite growth associated with Zn anode have become the main bottlenecks for the further development of zinc ion batteries (ZIBs).In this work,the electrochemical activity of H_(3)O^(+) is inhibited by the supramolecular host–guest complex composed of H_(3)O^(+) as guest and 18-crown-6 as host.The even Zn plating is induced by the host–guest complex electrostatic shielding layer on Zn anode,as detected by in-situ optical microscopy.The lamellar Zn is plated which profits from the improved Zn plating behavior.Density functional theory (DFT) calculation presents the stable structure of complex.The less produced H_(2) content is monitored online by a mass spectrometer during Zn plating/stripping,which indicates HER can be hampered by the host–guest behavior.Thus,the ZIBs with long life and high Coulombic efficiency are achieved via introducing 18-crown-6.The proposed host–guest supramolecular interaction is expected to facilitate the furthermore development of Zn batteries.

Insight into the effects of electrochemical factors on host-guest interaction induced signature events in a biological nanopore

The signature events caused by host-guest interactions in the nanopore system can be used as a novel and characteristic signal in quantitative detection and analysis of various molecules.However,the effect of several electrochemical factors on the host-guest interactions in nanopore still remains unknown.Here,we systematically studied host-guest interactions,especially oscillation of DNA-azide adamantane@cucurbit[6]inα-Hemolysin nanopore under varying pH,concentration of electrolytes and counterions(Li+,Na+,K+).Our results indicate correlations between the change of pH and the duration of the oscillation signal.In addition,the asymmetric electrolyte concentration and the charge of the counterions affects the frequency of signature events in oscillation signals,and even the integrity of the protein nanopore.This study provides insight into the design of a future biosensing platform based on signature oscillation signals of the host-guest interaction within a nanopore.

Host-guest interaction of β-cyclodextrin with isomeric ursolic acid and oleanolic acid:physicochemical characterization and molecular modeling study

Ursolic acid(UA) and oleanolic acid(OA) are insoluble drugs. The objective of this study was to encapsulate them into β-cyclodextrin(β-CD) and compare the solubility and intermolecular force of β-CD with the two isomeric triterpenic acids. The host-guest interaction was explored in liquid and solid state by ultraviolet-visible absorption,1H NMR, phase solubility analysis, and differential scanning calorimetry, X-ray powder diffractometry, and molecular modeling studies. Both experimental and theoretical studies revealed that β-CD formed 1: 1 water soluble inclusion complexes and the complexation process was naturally favorable. In addition, the overall results suggested that ring E with a carboxyl group of the drug was encapsulated into the hydrophobic CD nanocavity. Therefore, a clear different inclusion behavior was observed, and UA exhibited better affinity to β-CD compared with OA in various media due to little steric interference, which was beneficial to form stable inclusion complex with β-CD and increase its water solubility effectively.

Engineering singlet and triplet excitons of TADF emitters by different host-guest interactions

Understanding the host-guest interactions for thermally activated delayed fluorescence(TADF)emitters is critical because the interactions between the host matrices and TADF emitters enable precise control on the optoelectronic performance,whereas technologically manipulating the singlet and triplet excitons by using different kinds of host-guest interactions remains elusive.Here,we report a comprehensive picture that rationalizes host-guest interaction-modulated exciton recombination by using time-resolved spectroscopy.We found that the early-time relaxation is accelerated in polar polymer because dipole-dipole interaction facilitates the stabilization of the 1CT state.However,an opposite trend is observed in longer delay time,and faster decay in the less polar polymer is ascribed to theπ-πinteraction that plays the dominant role in the later stage of the excited state.Our findings highlight the technological engineering singlet and triplet excitons using different kinds of host-guest interactions based on their electronic characteristics.

Volumetric response of an ellipsoidal liquid inclusion: implications for cell mechanobiology

Elastic composites containing liquid inclusions exist widely in nature and engineering fields. The volumetric response of liquid inclusions is important in many cases, such as an isolated cell embedded in an extracellular matrix and an oil pocket embedded within shale. In this study, we developed a model for describing the volumetric response of an ellipsoidal liquid inclusion. Specifically, we investigated the volumetric response of an ellipsoidal liquid inclusion embedded in a three-dimensional (3D) matrix through an analytical expression of the volumetric response. We performed parametric analysis and found that loading along the shortest axis can induce the most volume change, while loading along the longest axis can induce the least volume change. We also found that the volumetric response decreases with increasing Poisson ratio of the matrix. These results could be used to understand some cell behavior in a 3D matrix, for example, cell alignment under mechanical load.

Studies on the Inclusion Behavior of Amphiphilic p-Sulfonatocalix[4]arene with Ascorbic Acid by Spectrofluorometric Titrations

The aqueous solution of tetrabutyl ether derivatives of p-sulfonatocalix[4]arene (SC4Bu) and ascorbic acid (AA) complex has been studied based on fluorescence and 1H NMR spectroscopic results. It was found that the fluorescence intensity of SC4Bu quenched regularly upon the addition of AA. A 1:1 stoichiometry for the complexation was established and was verified by Job’s plot. The temperature-dependent inclusion constants were calculated, form which Δ H and ΔS values were calculated. Meanwhile the proposed interaction mechanism of the inclusion complex was discussed based on 1H NMR results. The various factors (ionic strength, and surfactants) effecting the inclusion process were examined in detail.

Theoretical Study on the Inclusion Complex of β-Cyclodextrin and Nitrobenzene

Quantum chemical calculations were carried out to investigate the structures and properties for the inclusion complexes of nitrobenzene （NB） into β-cyclodextrin. Two low-energy conformations of β-cyclodextrin （A and B） in the gas phase were initially investigated by the PM3 and B3LYP/6-31＋G（d,p） calculations, respectively. Three different orientations were considered in the inclusion process of A and B with NB to form 1：1 complexes. Potential energy scan by PM3 calculations indicated that the phenyl orientation Ab for conformation A and the equator orientation Bc for conformation B are more favorable in energy, respectively. We also considered the 2：1 inclusion complexes of host A or B with guest NB in the gas phase. PM3 calculation indicated that the host-guest interaction energies to form 1：1 complexes are more negative than those to form 2：1 NB/B complexes. Finally, we studied the solvent effect of NB/CD complex, and PM3 results show that the influence of water molecules on the inclusion process is very important. The driving forces for the inclusion process and the geometries of complexes were discussed in detail.

Studies on Cyclodextrin Inclusion Complex by Fluorescence Anisotropy

An equation for determining the equilibrium association constant (KA) of cyclodextrin inclusion complex with fluorescence anisotropy is derived and used to determine KA of pyrene-B-cyclodextrin inclusion complex. The existing forms of cyclodextrin inclusion complex in solution, the interaction type of host with guest, and the possibility of application of B-cyclodextrin in the analysis of metal ions using naphthalene derivative as a ligand are discussed based on the equation derived along with the curve of fluorescence anisotropy versus cyclodextrin concentration of guest/cyclodextrin system.

Inclusion Property and Molecular Modeling of Calix[4]arene Derivatives

The inclusion properties of two calix[4]arene derivatives 5,11,17,23 tetra tert butyl 25, 27 bis (isopropyl carbamoyl methoxy) 26,28 diundecenyloxy calix[4]arene (C[4]A) and 25,27 dibutoxy 5,11,17,23 tetra tert butyl 26,28 diundecenyloxy calix[4]arene (C[4]B) were studied by gas chromatographic method. It was found that C[4]A could form inclusion complexes with benzene, toluene, methanol and ethanol while C[4]B could only form inclusion complex with methanol, which might be due to the different conformations of C[4]A and C[4]B. Molecular modeling showed that CH/π and OH/π interactions played important roles in the forming of inclusion complexes.

Inclusion behavior of oxybutynin with hydroxypropyl-β-cyclodextrin

Inclusion behavior of oxybutynin （OBN） with hydroxypropyl-β-cyclodextrin （HP-β-CD） was investigated by ultraviolet absorption spectrum and fluorescence spectrum. A reliable determination of the complex stoichiometry was provided by the continuous variation technique. Alcohol was added to further investigate the mechanism of the inclusion behavior. Thermodynamic constants AG, AH and AS for inclusion interaction of OBN and HP-β-CD were determined. The results show that host-guest complex with molar ratio of 1：1 is formed, and inclusion stability constant between OBN and HP-β-CD is 54.9 L/mol determined by ultraviolet spectrum and 11.1 L/mol determined by fluorescence spectrum. OBN has weak binding ability with HP-β-CD in aqueous solution （stability constant 〈102 L/mol） and addition of alcohol leads to a decrease of stability constant, which indicates that the hydrophobic force contributes to the inclusion process. AG, AH and AS are all less than zero, which indicates that the inclusion process is a spontaneous and exothermic process.

Host-guest interactions based supramolecular complexes self-assemblies for amplified chemodynamic therapy with H_(2)O_(2) elevation and GSH consumption properties

Although endogenous H_(2)O_(2) is overexpressed in tumor tissue,the amount of endogenous H_(2)O_(2) is still insufficient for chemodynamic therapy(CDT).In addition,the abundant cellular glutathione(GSH)could also consume·OH for reduced CDT.Thus,the elevation of H_(2)O_(2) and the consumption of GSH in tumor tissue are essential for the increased·OH yield and amplified CDT efficacy.In this paper,hostguest interactions based supramolecular complexes self-assemblies(SCSAs)were fabricated by incorporating cinnamaldehyde(CA)and PEG-modified cyclodextrin host units(m PEG-CD-CA)with ferrocene-(phenylboronic acid pinacol ester)conjugates(Fc-BE)on the basis of CD-induced host-guest interactions.After being internalized by cancer cells,CA can be released from SCSAs through the p H-responsive acetal linkage,elevating the H2O2level by activating NADPH oxidase.Then,Fc can catalyze the H_(2)O_(2) to higher cytotoxic hydroxyl radicals(·OH).Moreover,quinone methide(QM)can be produced through H_(2)O_(2)-induced aryl boronic ester rearrangement and further consume the antioxidant GSH.In vitro and in vivo experiments demonstrate that SCSAs can be provided as potential amplified CDT nanoagents.

2种环糊精与三氯苯酚相互作用的理论研究

通过相溶解度的实验和Autodock分子模拟对接技术探究了β-环糊精(β-CD)和羟丙基-环糊精(HP-β-CD)对2,4,5-三氯苯酚(TCP)的识别与增溶效果,结果发现TCP与β-CD和HP-β-CD均可形成分子量为1:1的包合物,且HP-β-CD/TCP包合物稳定性更好,最佳结合能为-5.20 kcal·mol^(-1)。利用溶液法制备了TCP与β-CD和HP-β-CD不同物质的量之比的包合物,当主客体物质的量之比为1:1时,两种环糊精包载率最高,分别为17.39%和16.26%。结合β-CD/TCP和HP-β-CD/TCP包合物的表征结果发现,TCP与β-CD和HP-β-CD不是简单的物理混合,而是TCP通过范德华力和疏水作用进入到β-CD和HP-β-CD空腔中形成稳定的包合物。

从数字鸿沟到数字包容:老年人参与乡村公共数字文化服务的推进路径

数字包容是弥合乡村老年人数字鸿沟与共享数字红利的价值选择与价值旨归。数字赋能老年人参与乡村公共数字文化服务的实质是供给与用户需求适配关系“分解”和“重构”的双向过程,旨在提升老年人参与乡村公共文化服务的契合性、可及性与均等性。老年人接受乡村公共数字文化服务过程中存在物质接入、技能使用与使用效果上的不平等,并形成主观抗拒与客观难题所带来的接入鸿沟、技术桥接失灵,社会支持缺乏所带来的使用鸿沟,以及文化反哺减弱与信息素养低所带来的知识鸿沟。因此,要以三元交互决定论为模型参照进行个体赋能,激活内生潜能,提升数字接入能力;社会赋能,驱动外部资源,提升数字使用能力;环境赋能,健全支持体系,提升数字获取能力。

Effects of anions on the structural regulation of Zn‑salen‑modified metal‑organic cage

By virtue of a 3∶1 complementary coordination strategy,a chiral heteroleptic metal-organic cage that con-tains divergent functional units,Pd‑R(Zn),was precisely constructed via self-assembly of monodentate variational Zn-salen ligands RZn and NADH(reduced nicotinamide adenine dinucleotide)mimic modified tridentate ligands with square-planar Pd ions.UV-Vis and luminescence spectra experiments reveal that different anions could selec-tively interact with different sites of Zn-salen modified metal-organic cages to achieve the structural regulation of cage compound,by using the differentiated host-guest electrostatic interactions of counter ions with metal-organic hosts.Compared to other anions,the presence of chloride ions caused the most significant fluorescence emission enhancement of Pd‑R(Zn),meanwhile,the UV-Vis absorption band attributed to the salen aromatic backbone showed an absorption decrease,and the metal-to-ligand induced peak displayed a blue shift effect.Circular dichro-ism and ^(1)H NMR spectra further demonstrate that the introduction of chloride anions is beneficial to keeping a more rigid scaffold.

CPL-active hybrid copper(Ⅰ)halides enabled by cation inclusion with chiral crown-ether

Chiral hybrid metal halides with high photoluminescence quantum yield(PLQY)and superior dissymmetry factor(g_(lum))are promising candidates for circularly polarized luminescence(CPL)emitting sources.However,it is a great challenge to achieve both high g_(lum)and large PLQY.Here,we report a new supramolecular strategy to fabricate chiral hybrid Cu(Ⅰ)-halides with nearunity quantum yields and intense CPL emissions.The dissymmetry factor can be dramatically modulated by tuning the hostguest complexations.Attributing to the chirality and variable conformations of the host-guest complexes,a series of chiral[G@L^(R/S)]_(2)Cu_(4)I_(6)have been prepared.The incorporation of different cations within the chiral L^(R/S)hosts leads to variations of packing modes along the c-axis and different extent of distortions in the[Cu_(4)I_(6)]_(2)-polyhedra.Among them,[H_(3)O@L^(R/S)]+cations are stacked based on Van der Waals interactions and hierarchically self-assemble into a right/left-handed helix in[H_(3)O@L^(R/S)]_(2)Cu_(4)I_(6),which results in a high g_(lum)of-7×10^(-3)and a large PLQY of 96.92%.Notably,[G@L^(R/S)]_(2)Cu_(4)I_(6)shows promising applications in single-component white light emitting diodes(WLEDs),exhibiting a maximum dissymmetry factor of-1.2×10^(-3).The effective host-guest complexation and oriented hierarchical self-assembly provide an effective strategy for the development of high-performance CPL materials.