A New Cadmium(Ⅱ) Coordination Polymer Extended through Hydrogen Bonds and π-π Stacking Interactions: Synthesis and Photoluminescence Property

A new coordination polymer, {[Cd(OPY)(tdc)(HO)]·H2 O}n(OPY = 4,4?-(oxybis(4,1-phenylene))dipyridine, H2 tdc = thiophene-2,5-dicarboxylic acid), has been synthesized hydrothermally based on a V-shaped ligand OPY. The structure was fully characterized by elemental analysis, FT-IR spectroscopy, and X-ray single-crystal diffraction analysis. In1, two OPY ligands and one water molecule acted as terminal ligands coordinating to Cdcation to form [Cd(OPY)HO]units, which are then linked by tdc2-ligands to generate a one-dimensional chain. Every two adjacent chains linked by extensive O–H···O hydrogen bonds constitute one-dimensional double-chains, and such chains are extended into two-dimensional layers via O–H···N hydrogen bonds. These layers are further connected to form a three-dimensional supramolecular architecture via π-π stacking interactions. In addition, the thermal stability and solid state fluorescence property of 1 were also investigated.

Theoretical Investigations on the π-π Stacking Interactions in Phenol-Water Complexes

Non covalent interactions are quite common in all kinds of π-systems, such as π-π interactions, long range/short range van der waal force of interactions, ion-π interactions etc. Ab initio calculations are well established and account well for the experimental long range interaction energies for small clusters of aromatic molecules and most of the calculations were carried out using the MPn methods. If a reasonably large basis set is used to calculate the stacking interaction energies for a cluster (dimer, trimer etc.) of aromatic molecules then the electron-electron correlation energy may be properly calculated. Moreover, ab initio calculations for aromatic π-systems show that the calculated stacking interaction energies highly depend on the basis set used and the electron correlation energy. In this investigation, the electron correlation of the stacked hydrated phenol systems has been accounted at MP2 level of calculations. We have calculated the π-π stacking interaction energies of the hydrated phenolic systems with different conformations.

Quantum Mechanical Study on the π-π Stacking Interaction and Change in Conformation of Phenolic Systems with Different Intermolecular Rotations

Aromatic systems like phenol, diphenol, cyano benzene, chloro benzene, aniline etc shows effective π-π stacking interactions, long range van der Waals forces;ion-π interactions etc. and these forces of interactions play an crucial role in the stability of stacked π-dimeric system. On the other hand, substituents and conformational change in the stacked dimmers of aromatic system may also change the stability of different stacked dimers. In this current study, stacked phenolic dimmers (both phenol and diphenol) have been taken for investigation of the stacking π-π interaction. But, the stacking interactions are also greatly affected by the conformational change with internal rotation (i.e. dihedral angle, φ) between the stacked dimers. It is generally accepted that larger basis sets are required for the highly accurate calculation of interaction energies for any stacked aromatic models. But, it has recently been reported that M062X/6-311++G(d,p) basis set is effectively better than that of B3LYP/6-311++G(d,p) for determining the interaction energies for any kind of long range interaction in aromatic systems. Therefore, all the calculations were carried out by using M062X/6-311++G(d,p) basis set. However, in most of the cases the calculated π-π stacking interaction energies show almost same result for both DFT and ab initio methods.

Enhanced photochemical oxidation ability of carbon nitride by π-πstacking interactions with graphene

A one-pot method for the preparation of g-C3N4/reduced graphene oxide（rGO） composite photocatalysts with controllable band structures is presented.The photocatalysts are characterized by Fouirer transform infrared spectroscopy,X-ray diffraction,scanning electron microscope,transmission electron microscope,and Mott-Schottky analysis.The valance band（VB） of g-C3N4 exhibits a noticeable positive shift upon hybridizing with rGO,and thus results in a strong photo-oxidation ability.The g-C3N4/rGO composites show a higher photodegradation activity for 2,4-dichlorophenol（2,4-DCP） and rhodamine B（RhB） under visible light irradiation（λ≥420 ran）.The g-C3N4/rGO-1sample exhibits the highest photocatalytic activity,which is 1.49 and 1.52 times higher than that of bulk g-C3N4 for 2,4-DCP and 1.52 times degradation,respectively.The enhanced photocatalytic activity for g-C3N4 originates from the improved visible light usage,enhanced electronic conductivity and photo-oxidation ability by the formed strong π-π stacking interactions with rGO.

基于mRMR-BO优化Stacking集成模型的NO_(x)浓度动态软测量

针对火电厂选择性催化还原(selective catalytic reduction,SCR)烟气脱硝系统中,由于影响入口NO_(x)质量浓度因素过多及系统大迟延大惯性,导致入口NO_(x)质量浓度难以准确及时测量的问题,提出了利用最大相关-最小冗余算法(max-relevance and min-redundancy,mRMR)结合贝叶斯优化算法(Bayesian optimization,BO)优化Stacking集成模型的SCR烟气脱硝系统入口NO_(x)质量浓度动态软测量模型。针对动态NO_(x)生成过程中静态单一模型预测精度降低及辅助变量与入口NO_(x)质量浓度时间异步的问题,利用mRMR-BO结合模型进行辅助变量筛选,Copula熵(copula entropy,CE)确定辅助变量迟延,BO结合模型确定辅助变量阶次,将TCN及LASSO利用Stacking法集成,使用含有迟延时间及阶次信息的辅助变量构建动态Stacking集成软测量模型。仿真结果显示:集成模型较TCN及LASSO单一网络的均方根误差、平均绝对误差、平均绝对百分比误差最小;动态集成模型对比静态集成模型,预测精度更高,能够实现对入口NO_(x)质量浓度的准确软测量。

A Silver Complex of 6,7-Dicyanodipyridoquinoxaline:π-Stacking Interactions and Luminescence

The reaction of 6,7-dicyanodipyridoquinoxaline （DICNQ） with AgNO3 in a 1：1 molar ratio by solution method gave a new complex [Ag（DICNQ）2]NO3 1. Single-crystal X-ray diffraction analysis reveals that the complex crystallizes in the space group Ibca of orthorhombic system with eight formula units in a cell. Crystal data for 1： a = 15.7055（17）, b = 18.411（2）, c = 20.680（2）A, V = 5979.7（11）A3, Z = 8, C32Hl2AgN13O3, Mr = 734.42, Dc = 1.632 g/cm3, μ= 0.734 mm-1, F（000） = 2928, S = 1.023 and T= 293（2） K. The final R = 0.0659 and wR = 0.1927 for 2118 observed reflections with I 〉 2σ（I）, and R = 0.0801 and wR = 0.2196 for all data. The complex builds up a packing structure by π-π stacking interactions and shows a luminescent feature.

THE INTRAMOLECULAR AROMATIC-RING STACKING INTERACTION OF MIXED LIGAND PALLADIUM(Ⅱ)COMPLEXES Ⅲ.STUDIES ON THE Pd^(2+)-A-UTP^(4-)SYSTEMS BY HNMR

The intramolecular aromatic-ring stacking interaction of mixed- ligand complex Pd(A)(UTP)^(2-)in the system pd^(2+)-A-UTP^(4-)has been determined by ~1HNMR,where A=1,10-phenanthroline(phen),2,2'-bipyridyl(bpy)and DL- tryptophan(trp^-);UTP^(4-)=uridine 5-triphosphate.The result indicates that it is the partial stacking between the uracil ring of UTP^(4-)and the heterocyclic ring of A that makes H(5),H(6)and H(1')in the UTP^(4-)shift upfield signifi- cantly.Accordingly,the order of aromatic-ring interaction in the mixed- ligand complex has been obtained as follows:Pd(phen)(UTP)^(2-)(?)Pd(bpy)(UTP)^(2-) Pd(trp)(UTP)^(3-).

Self-aggregating behavior of poly(4-vinyl pyridine)and the potential in mitigating sand production based onπ-πstacking interaction

Unconsolidated sandstone reservoirs are most susceptible to sand production that leads to a dramatic oil production decline.In this study,the poly(4-vinyl pyridine)(P_(4)VP)incorporated with self-aggregating behavior was proposed for sand migration control.The P_(4)VP could aggregate sand grains spontaneously throughπ-πstacking interactions to withstand the drag forces sufficiently.The influential factors on the self-aggregating behavior of the P_(4)VP were evaluated by adhesion force test.The adsorption as well as desorption behavior of P_(4)VP on sand grains was characterized by scanning electron microscopy and adhesion force test at different pH conditions.The result indicated that the pH altered the forms of surface silanol groups on sand grains,which in turn affected the adsorption process of P_(4)VP.The spontaneous dimerization of P_(4)VP molecules resulting from theπ-πstacking interaction was demonstrated by reduced density gradient analysis,which contributed to the self-aggregating behavior and the thermally reversible characteristic of the P_(4)VP.Dynamic sand stabilization test revealed that the P_(4)VP showed wide pH and temperature ranges of application.The production of sands can be mitigated effectively at 20-130℃ within the pH range of 4-8.

STUDY ON THE STABILITY AND STACKING INTERACTION EFFECT OF THE TERNARY M(Ⅱ)(ATP)AND PYRIDINE-LIKE LIGANDS

The stabilities of the complexes of three pyridine-like ligands with M(II)(ATP)^(2-) and M(II)(M=Ni,Co)were studied by spectrophotometry and by comparing the stability constants of the ternary complexes with these of the binary complexes.A stacking interaction between the pyridine ring and the purine ring of ATP is indicated.The general existence of the stacking interaction encourages us to interpret the antitumor mechanism of a new class of antitumor drugs.

Thermal Stability Improved by π–π Stacking Interactions: Synthesis, Crystal Structure and Thermal Decomposition of Sodium Nitroformate

An energetic salt, sodium nitroformate （NaNF）, was synthesized and characterized by elemental analysis, IR and UV spectra, and its crystal structure was first determined by single crystal X-ray diffraction. The structure exhibits two types of π-π stacking interactions between the nitroformate anions, i e, the parallel-displaced and T-shaped confgurafions. Furthermore, the thermal decomposition mechanism was investigated by DSC, TG-DTG and FTIR techniques. The kinetic parameters of the thermal decomposition were also calculated by using Kissinger＇s and Ozawa-Doyle＇s methods. The results show that NaNF has a good thermal stability, which is attributed to the π-π stacking interactions.

Solvents incubatedπ-πstacking in hole transport layer for perovskite-silicon 2-terminal tandem solar cells with 27.21%efficiency

Room temperature sputtered inorganic nickel oxide(NiO_(x))is one of the most promising hole transport layers(HTL)for perovskite-sillion 2-terminal tandem solar cells with the aid of ultrathin and compact organic layers to passivate the surface defects.In this study,the aromatic solvent with different substituent groups was used to regulate the conformation of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)am ine](PTAA)layer.As a result,the single-junction perovskite solar cell(PSC)gained a power conversion efficiency(PCE)of 20.63%,contributing to a 27.21%efficiency for monolithic perovskite/silicon(double-side polished)2-terminal tandem solar cell,by applying the alkyl aromatic solvent to enhance theπ-πstacking of PTAA molecular chains.The tandem solar cell can maintain 95%initial efficiency after aging over 1000 h.This study provides a universal approach for improving the photovoltaic performance of NiO_(x)/polymer-based perovskite/silicon tandem solar cells and other single junction inverted PSCs.

Studies on Intramolecular Stacking Interaction of Ternary Complexes M（Ⅱ）（ATP）￣（2－） with Heteroaromatic N－Base Ligands

o understand the driving forces leading to mixed-ligand complexes in biologi-cal systenis.ternary complexes of M (ATP(L￣(2-) type, where M = Cu￣(2+), Ni￣(2+) orCo￣(2+) , and L= pyridine(Py) , 4-picoline, 3, 5-lutidine, isoquinoline (lq) or benzimi-dazole(Bi) in aqueous solution were studied by spectropliotometry, some of them(M=Cu￣(2+), L = isoquinoline or benzimidazole) were also separately studied hy po-tentiometric pH titration. The results show that an intramolecular stacking interac-tion exists between the heteroaromatic ring of the ligands and the purine moiety ofATP.

A model study on the stacking interaction of phenanthroline ligand with nucleic acid base pairs: An ab initio, MP2 and DFT studies

The stacking of phenanthroline(phen) ligand within base pair sequences is one of the important factors for the stabilization of metalphen complex within DNA. The stacking ability of this ligand has been assessed to deduce the base pair selectivity as well as to identify the favored region of intercalation. Different level of theories have been used to predict the favorable regions for stacking interaction of phen ligand with base pair, but the results of MP2/6-31+G(d,p) is found to be reasonably good for monitoring such interactions.

Pi Stacking Interactions in Two TPT Derivatives and Their Photoluminescence Characters

π-π Stacking in the 2,4,6-tris（4-pyridyl）-1,3,5-triazine aromatic nitrogen-containing ligand and its metal-ligand complex Zn（TPT）2（H2O）4（OH）2 1 has been investigated by single-crystal X-ray diffraction analyses. The stacking mode of the ligand changes from the offset conformation to a perfect face-to-face alignment with the coordination to the zinc centers. The structure features are correlated with their solid-state luminescence properties. With excitation at 360 nm, free TPT ligand gives a strong fluorescent emission at 455 nm and the ligand-centered emission of the metal-ligand complex occurs at the same wavelength with lower emission intensity. The distance between the aromatic rings responds to the difference of luminescence characters.

CNDO Studies on the Intermolecular Coulomb Interaction in TCNQ-Stack

The coulomb interaction among TCNQ- molecules in different stack structures was calculated by quantum chemistry CNDO method. The results of the calculation would be used to explain the change rule of the electricity property of the TCNQ complex very well.

Unusual F_(3)stacking fault in magnesium

An unusual F_(3)basal stacking fault resulting from twin-dislocation interaction in magnesium is observed in molecular dynamics simulation.The F_(3)fault is produced in the twin lattice from the interaction between a migrating(1012)twin boundary and a partial dislocation of either a prismatic<c>edge,or a prismatic<c+a>mixed dislocation in the matrix.The condition is that the partial dislocation needs to have a negative sign and lie on a plane intersecting a compression site of the twin boundary.The F_(3)fault can also be generated when a positive basal<a>mixed dislocation in the twin lattice,with slip plane intersecting a compression site of the twin boundary,interacts with a basal-prismatic twinning disconnection.The F_(3)fault comprises two I_(1) faults that have the same character but are separated by two basal layers.It has one end connected to the twin boundary,and the other end bounded by a lattice defect with a Burgers vector identical to that of a 30°Shockley partial dislocation.The formation frequency of the F_(3)fault is higher at a lower shear stress(below∼400 MPa)and/or a lower temperature(100 K and 200 K).The F_(3)fault can decompose into a glissile 30°Shockley and a T_(2) fault at a temperature above∼400 K.The relationships between the F_(3)fault and other types of basal stacking faults such as I_(2),T_(2) or paired I_(1) faults that are separated by multiple basal layers are discussed.

Elastic responses of underground circular arches considering dynamic soil-structure interaction:A theoretical analysis

Due to the wide applications of arches in underground protective structures, dynamic analysis of circular arches including soil-structure interactions is important. In this paper, an exact solution of the forced vibration of circular arches subjected to subsurface denotation forces is obtained. The dynamic soil-structure interaction is considered with the introduction of an interfacial damping between the structure element and the surrounding soil into the equa- tion of motion. By neglecting the influences of shear, rotary inertia and tangential forces and assuming the arch incompressible, the equations of motion of the buried arches were set up. Analytical solutions of the dynamic responses of the protective arches were deduced by means of modal super- position. Arches with different opening angles, acoustic impedances and rise-span ratios were analyzed to discuss their influences on an arch. The theoretical analysis suggests blast loads for elastic designs and predicts the potential failure modes for buried protective arches.

Interaction of 14-3-3σ with KCMF1 suppresses the proliferation and colony formation of human colon cancer stem cells

AIM: To investigate the biological function of 14-3-3σ protein and to look for proteins that interact with 14-3-3σ protein in colon cancer stem cells. METHODS: Reverse transcription polymerase chain reaction was performed to amplify the 14-3-3σ gene from the mRNA of colon cancer stem cells. The gene was then cloned into the pGEM-T vector. After being sequenced, the target gene 14-3-3σ was cut from the pGEM-T vector and cloned into the pGBKT7 yeast expression plasmid. Then, the bait plasmid pGBKT7-14-3-3σ was transformed into the yeast strain AH109. After the expression of the pGBKT7-14-3-3σ fusion protein in the AH109 yeast strain was accomplished, a yeast two-hybrid screening assay was performed by mating AH109 with Y187 that contained a HeLa cDNA library plasmid. The interaction between the 14-3-3σ protein and the proteins obtained from positive colonies was further confirmed by repeating the yeast two-hybridscreen. After extracting and sequencing the plasmids from the positive colonies, we performed a bioinformatics analysis. A coimmunoprecipitation assay was performed to confirm the interaction between 14-3-3σ and the proteins obtained from the positive colonies. Finally, we constructed 14-3-3σ and potassium channel modulatory factor 1 (KCMF1) siRNA expression plasmids and transfected them into colon cancer stem cells. RESULTS: The bait plasmid pGBKT7-14-3-3σ was constructed successfully, and the 14-3-3σ protein had no toxic or autonomous activation effect on the yeast. Nineteen true-positive colonies were selected and sequenced, and their full-length sequences were obtained. We searched for homologous DNA sequences for these sequences from GenBank. Among the positive colonies, four coding genes with known functions were obtained, including KCMF1 , quinone oxidore-ductase (NQO2 ), hydroxyisobutyrate dehydrogenase (HIBADH ) and 14-3-3σ . For the subsequent coimmu-noprecipitation assay, the plasmids PCDEF-Flag-14-3-3σ, PCDEF-Myc-KCMF1, PCDEF-Myc-NQO2 and PCDEF-Myc-HIBADH were successfully constructed, and the sequences were further confirmed by DNA sequencing. The Fugene 6 reagent was used to transfect the plasmids, and fluorescence-activated cell sorting analysis showed the transfection efficiency was 97.8% after 48 h. The HEK 293FT cells showed the stable expression of the PCDEF-Flag-14-3-3σ, PCDEF-Myc-KCMF1, PCDEF-Myc-NQO2 and PCDEF-Myc-HIBADH plasmids. After anti-Myc antibody immunoprecipitation with Myc-KCMF1, Myc-NQO2 and Myc-HIBADH from cell lysates, the presence of Flag-14-3-3σ protein in the immuno-precipitated complex was determined by western blot analysis. The knock-down expression of the 14-3-3σ and KCMF1 proteins significantly inhibited cell proliferation and colony formation of SW1116csc. CONCLUSION: Genes of the proteins that interactedwith 14-3-3σ were successfully screened from a HeLa cDNA library. KCMF1 and 14-3-3σ protein may affect the proliferation and colony formation of human colon cancer stem cells.

Jet formation in shock-heavy gas bubble interaction

The influences of the acoustic impedance and shock strength on the jet formation in shock-heavy gas bubble interaction are numerically studied in this work. The process of a shock interacting with a krypton or a SF6 bubble is studied by the numerical method VAS2D. As a validation, the experiments of a SF6 bubble accelerated by a planar shock were performed. The results indicate that, due to the mismatch of acoustic impedance, the way of jet formation in heavy gas bubble with different species is diversified under the same initial condition. With respect to the same bubble, the manner of jet formation is also distinctly different under different shock strengths. The disparities of the acoustic impedance result in different effects of shock focusing in the bubble, and different behaviors of shock wave inside and outside the bubble. The analyses of the wave pattern and the pressure variation indicate that the jet formation is closely associated with the pressure perturbation. Moreover, the analy- sis of the vorticity deposition, and comparisons of circulation and baroclinic torque show that the baroclinic vorticity also contributes to the jet formation. It is concluded that the pres- sure perturbation and baroclinic vorticity deposition are the two dominant factors for the jet formation in shock-heavy gas bubble interaction.