CD Spectroscopic Study on the Molecular Recognition of Chiral Salen－Metal Complexes

The molecular recognition behavior of the chiral salen-metal complexes towards guest molecules, such as imidazole derivatives and amino-acid ester, was systematically investigated by means of circular dichroism (CD) spectra. The coordination numbers of the host-guest complexes as well as the recognition capability of the salen-metal complexes were explained by character and intensity analyses of the CD spectra.     

Studies on Colloidal Properties of Mixed Metal Hydroxide－Clay Aqueous Suspension

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Comparative Study on the Inclusion Complexation of Rutin with Cyclodextrin Supramolecules

Naturalandchemicallymodifiedcyclodextrinshaveabilitytorecogformanyinorgan-..icororganlcguestmoleculesfOrminghost-guestinclusioncomplexest13.Inrecentyears,increasingattentionhasbeenpaidtoalterphisical,chemicalandbiologicalpropertiesofmolecules'-Theunderstanding'ofthebehaviorofthedrugincyclodextrionmicroenwton-mentisaprerequisitetodevelopmentofanovelandeffectivecarrierspptemforthedrug.6-CDcanforminclusioncomplexeswithrutin[2J.WereporthereastudyoninclusioncomplexationofcyClodextrinsbyfluorAnetr…     

Study of the Complexation Behavior of Calixarene with Transition Metal Cations by UV—vis and Fluorescent Spectra

A new fluorescent compound based on calix[4] arene skeleton was synthesized.Its complexation ability with transition metal ions,such as Fe^3 ,Co^2 ,Ni^2 ,Cu^2 ,Zn^2 and Ag^ ,Was investigated by UV-vis and fluorescent spectra.     

Study on Thermosensitive Micellization of Dextran-g-PNIPAAm in Aqueous Solutions

Poly(N-isopropylacrylamide) (PNIPAAm) is a well-known thermosensitive polymer. It shows the lower critical solution temperature (LCST) of about 32℃ in aqueous solution. Many PNIPAAm containing amphiphilic copolymers have been reported. The most frequentl…     

Effect of pH on the Rheology of Al-Mg Mixed Metal Hydroxide——Montmorilonite Aqueous Suspension

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A Spectrophotometric Study on the Host-Guest Complexation of β-Cyclodextrin with 3-Indolyl Acetate in Dilute Aqueous Solution by Determining Solubility of Guest Substance

Interestincyclodextrinshasincreasedsteadily,becausetheirinclusioncompoundshaveprovedmoreandmoreusefulinbothresearcllandindustry'.Furthermore,theyareofgreatilllportanceforsupramolecularchemistry,sincetheyaremembersofahomologousseriesofW'ater-solubleandchiralhostmoleculeswhichcanbeusedasmodelsforstudyingweakinteractionsl-'.Ontheotherhand.indolylgroupexistsinsomeimportantbiogentcsubstancessuchastryptophan.Soinvestigationontheinteractionsbetweenindolylderivativesandsuchbiologicmodelsubstancesascyc…     

Complexation Properties of a Carbon-Bridged Cryptand with Metal Ions in Aqueous Solution at 25°C

Abstract

Thermodynamic quantities (log K, ΔH, and ΔS) for the interactions of a carbon-bridged cryptand with Li⁺, Na⁺, K⁺, Ca²⁺, Sr²⁺, Ba²⁺, and Pb²⁺ were determined at 25° C by calorimetric titration in aqueous solution. The cryptand forms complexes with Na⁺, Sr²⁺, Ba²⁺, and Pb²⁺ with log K ≤ 2. Complexation was not detected for Li⁺, K⁺, and Ca²⁺. Weak interactions with Li⁺ and K⁺ and a log K value of 2.4 for Na⁺ suggest that the cavity size of the cryptand is close to that of Na⁺ but too small for K⁺ and too large for Li⁺. The carbon-bridged cryptand selectively binds Sr²⁺ (log K = 3.2) over Ca²⁺ and Ba²⁺ by more than one order of magnitude.     

Theoretical Study on the Mass Transfer of Metal Ions in Ion Exchange Process

The kinetics of ion exchange between Ca2 , Mg2 , Co(Ⅱ), Cu(Ⅱ),Ni(Ⅱ), Fe(Ⅲ), y3 or Sm3 , respectively, in 0.50 mol/L HC1 and H on macrorecticular sulfonic ion exchange resin and the kinetics of the same reactions (M -H exchange) when Mn(Ⅱ) coexisted in resin phase as accelerating ion were studied. The accelerating effect manifested and its rule are consistent with the accelerating effect theory based on the concept concerned with adsorption electrical double layer which has been suggested in a previous paper published.     

The Study on the Thermal Stability of CLA in Egg Yolk

Conjugated linoleic acids (CLA) have been a subject of extensive investigation for their anticarcinogenic, hypolipidemic, antiatherosclerotic and immune-enhancing activities. Stability of CLA in foods has not received much attention by both academics and industry. Although CLA has shown many beneficial effects, its decomposition must be prevented when CLA in foods is processed, stored and transported. However, no study to date has addressed the stability of CLA in foods. The present stud…     

A Gold Electrode QCM Study on the Self-Assembling Process of Thioglycollic Acid in Aqueous Solution

Quartzcrystalmicrobalance(QCM)iswellknownasanexcellenttoolforthestudyofchemicaland/orphysicalprocessesonthesolidsurfaceaccompaniedbymasschangedowntoananogramlevell.Inaddition,itiswellestablishedthatathiol-containingcompoundisabletoadsorbonsomesubstrates(e.g.,An,Cu,andCd)toformaself-assembledmonolayerbythewell-knownchemicalreactionofthethiolgroupwiththesubstrate2.Tothebestofourknowledge,therearenoreportsontheself-assemblingprocessesofalkanethiolcompoundsinaqueoussolutionswithQCMteclmique.In…     

Quantum Chemistry Study on the Geometrical Structures of Small Centipedo－boranes

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The Adsorption of Aqueous—Organic Mixture Components on Cellulose

The isotherms of composition changes were obtained for the cellulose—water—dimethylsulfoxide and cellulose—water—acetonitrile systems. The isotherms of sorption of aqueous—organic mixture components on cellulose were calculated. The heat effects of wetting of cellulose with water—dimethylsulfoxide and water — acetonitrile solutions were measured. The special features of sorption of the components on cellulose were shown to be related to the character of cluster formation in the binary systems under consideration.     

Study on the Interaction of Pentachlorophenol with Urease in Aqueous Solution by Multiple Spectroscopic Techniques

The interactions between pentachlorophenol (PCP) and jack bean urease were studied using UV/vis absorption, CD, fluorescence, synchronous fluorescence, and three-dimensional fluorescence spectroscopic techniques. The fluorescence data showed that the fluorescence quenching of urease by PCP the results of the formation of a PCP–urease complex involving a hydrophobic interaction. The distance r between the donor (urease) and acceptor (PCP) was obtained from the fluorescence resonance energy transfer. The effect of PCP on the conformation of urease was analyzed using UV/vis absorption, synchronous fluorescence and three-dimensional fluorescence spectroscopic techniques. The result showed that PCP can enter into the hydrophobic pocket at the interface of urease and that the micro environments around the tyrosine and tryptophan residues were changed.     

Modification of Metal Complex on the StereoselectiveHydrogenation of 2,3-Butanedione

Nanoscopic metal clusters, because of their substantial difference from metal atoms and bulk metals in size and structure, have attracted great interest especially in the field of catalysis1. It is well known that additives can markedly affect the properties of metal catalysts. The effect of metal ions has been well studied in the field of heterogeneous catalysis2. However, the study of metal complex effect is scarce. We have reported that the metal complex can considerably modulate both the a…     

A PM3 Molecular Orbital Study on the Conformational Equilibrium of Cyclohexane upon α-Cyclodextrin Inclusion Complexation

The effect ofα-cyclodextrin (α-CD) inclusion complexation on the conformational equilibrium of cyclo- hexane wasstudied with thesemiempirical PM3 molecularorbital calculations. The calculation results indicated that the chair form of cyclohexane is 18.5 kJ·mol-1lower than that of boat one in energy, however, theα-cyclodextrin inclusion complex of boat cycl ohexane is 4.4 kJ·mol-1more stable than the complex of chair form. It demon-strated that the conformational equilibrium of cyclohexane was influenced by theα-CD inclusion complexation. Hence, caution should be given when extrapolating the conformational behaviors of the guest compounds in the supramolecular systems totheir free forms, since the interactionsbetween the host and guest significantly affect the conformation of the guest compounds.     

Study on the hydrogenation coupling of methane

At atmospheric pressure and ambient temperature, the hydrogenation coupling of methane was studied by using pulse corona plasma and its synergism with catalyst. The results showed that (i) under pulse corona plasma, the coupling of methane could be fulfilled by the addition of hydrogen, and with the increase of the amount of hydrogen, the conversion of methane and the yield of C2 hydrocarbon increased, and the deposit of carbon decreased; (ii) the conversion of methane was affected by pulse voltage and repeated frequency; (iii) in the system, the addition of Ni/y-AI203 could improve the distribution of C2 hydrocarbon; (iv) the activity of Ni/y-AI2O3 prepared by cold plasma was better than that by chemical methods. The experiment opened up a new technical route of the coupling of methane.     

Study on the Reaction of α-Ketohemithioacetal

Aromatic α-sulfinyl carboxylic acids can be rearranged to hemithioacetals or other derivatives of glyoxylic acid under the action of acid reagents was first reported by Pummerer¹. Later, Russell and coworkers applied this rearrangement to β-ketosulfoxides, synthesized α-ketohemithioacetal², which can be transformed to α-keto alcohol, α-keto aldehyde and α-hydroxy alcohol, α-hydroxy acid³. Furthermore, Hall and Poet reported that α-ketohemithio-acetal can be rearranged to the corresponding α-hydroxythioester in the presence of magnesium nitrate and sodium acetate or tertiary amine⁴. However, few reports of reaction of α-ketohemithioacetal can be seen in literature.     

Study on the Reaction of α-Thiobenzoylthioformylmorpholine

a-ThiocaIbonylthiOformnddesareOfalmostunexploredclassOfcomPOundsll],althoughtheyhavebeenpreParedsincel98Ol2-3].ThisattractSustoexploretheirchendStryandutilityinSynthesisOfheteropcles.Accordingtoourpreviousmethodl`1,a-benzOylthiOfOrmyl-morpholine1wasprePaIedfirst,fOllowedbysumirizationOfcarbonylwithLawessenreagnttoaffordtheexpeCtedcr-thjobenzoylthiOformylmorpholine2,whchhastWothiotnylgrous.onthebasisOfstructUreof2,itcanbereactedwithcomPOundsbearingdrinctionalgrouP,suchasdidrineandsen…     

The Effect of pH Difference Between Two Phases on the Partition of Lysozyme in Aqueous Two-Phase System

Aqueoustwo-phasesystems(ATPS)areformedwhentwoaqueoussolutionsofhydrophilicpolymersorapolymerandasaltaremixedathighconcentration.Forthechargedproteins,AlbertssonhasdevelopedtheclassicalmodelfortheelectrochemicalpartitioninginATPSfInK,=lnK, (Z,F/RT)Arp(l)HereK,denotesthepartitioncoefficientofproteins,InK,includesalltheotherfactorsaffectingproteinpartitioning,and(Z,F/RT)A(PistheelectrostatictermasaproductofproteinsurfacechargeZPandAam,theelectrostaticpotentialdifferencebetweenthetwopha…