COMPLEX FORMATION BETWEEN ALCOHOLS AND THE AROMATIC HYDROCARBONS PYRENE AND 1-METHYLPYRENE

Abstract—Pyrene and 1-methylpyrene have been shown by infrared spectrometry to form 1:I molecular complexes with alcohols at a concentration of 0.02 M in CCl₄ solutions. The association constants are of the order of 1 M^-1. The fluorescence decay profiles of 10μM pyrcnc in dilutc butanol-heptane solutions have been found to be the sum of two exponential components in agreement with ground state complex formation     

COMPLEX FORMATION BETWEEN PYRENE AND THE NUCLEOTIDES GMP, CMP, TMP AND AMP

Pyrene has been found to form ground and excited electronic state complexes of 1:1 stoichi-ometry with GMP, CMP, TMP and AMP. The values of their ground state association constants are 45 M^-1, 13M^-1, 14 M^-1, and 52 M^-1 respectively. The fluorescence of pyrene is strongly quenched by GMP, CMP, and TMP but only slightly by AMP. Fluorescence quenching analysis has yielded the values 87M^-1, 73 M^-1, and 154 M^-1 for the excited state association constants with GMP, CMP, and TMP, respectively. The corresponding values for the excited state second-order rate constant for complex formation are: 3.3 times 10⁹M^-1 s^-1 4.1 times 10⁹M^-1 s^-1, and 4.0 times 10⁹M^-1 s^-1. The probabilities of complex formation per collision between an excited pyrene molecule and a nucleotide are: 0.52, 0.64, and 0.63. The values for the excited state rate constant for dissociation of the complex are: 3.8 times 10⁷s^-1 5.6 times 10⁷s^-1, and 2.6 times 10⁷s^-1. The possibility is discussed that partial transfer of charge from pyrene to nucleotide may be playing a role in the complex formation process.     

COMPLEX FORMATION BETWEEN ETHIDIUM BROMIDE AND THE NUCLEOTIDES AMP AND GMP

Abstract— The antimicrobial drug ethidium bromide (EB) has been found to form molecular complexes with nucleotides, the strongest being those with the purines AMP and GMP. For the EB-AMP and EB-GMP complexes (which we characterized) the values of the ground-state association constant have been found to be 100 and 103 M ^-1, respectively. The fluorescence of the drug is enhanced when complexed to AMP, GMP, and TMP by about 60, 30 and 10%, respectively, whereas it is quenched by about 20% when complexed to CMP. Fluorescence enhancement analysis has yielded the values of 1.1 × 10¹⁰ and 0.7 × 10¹⁰ M ^-1 s^-1 for the excited-state rate constant of complex formation with the former two nucleotides, respectively. About one out of two collisions between an excited EB molecule and an AMP or GMP molecule results in complex formation. The potential implications of these findings for the EB-DNA interaction are discussed.     

REACTIONS OF THIOPHENES AND ACETYLENES IN POLAR AND APOLAR SOLVENTS

Abstract

Although the aromatic 6π-electron system of thiophenes is rather unreactive in cycloaddition reactions we have found that several thiophene derivatives react with acetylenes. Alkylthiophenes undergo (2+2)-cycloaddition reactions with electron-deficient acetylenes in apolar solvents in the presence of Lewis acids to give 2-thia-bicyclo [3. 2. 0] hept-3, 6-dienes (1). These compounds show isomerization via an a, a-Cope rearrangement at temperatures of 100 to 150°C.     

KINETICS AND MECHANISM OF COMPLEX FORMATION BETWEEN [PtCl(DIEN)]+ AND THIOLS AND THIOETHERS

Abstract

Reactions of the monofunctional platinum(II) complex, [PtCl(dien)]⁺, with different thiols and thioethers, including biologically important molecules, have been studied as a function of temperature (288.2–308.2K) using conventional electronic spectrophotometry in 0.10 M aqueous hydrochloric acid and by ¹H NMR spectroscopy. The second-order rate constants, k₂, are similar, varying between 1.43 × 10^?3 and 46.1 × 10^?3 M^?1s^?1 at 25°C. The reactivity follows the sequences: D-penicillamine ≤ L-cysteine ≤ glutathione ≤ thiodiglycolic acid ≤ thioglycolic acid ≤ L-methionine ≤ S-methylthioglycolic acid ≤ glycyl-D,L-methionine. However, variation in size, bulkiness and solvation of the entering ligands reflect in their properties as nucleophiles. Large negative values of the entropy of activation (ΔS≠), between ?140 and ?190 J K^?1 mol^?1, indicate that all thiols and thioethers react via the same associative mechanism. Results have been analyzed in relation to the antitumor activity and toxicity of platinum(II) complexes.     

COMPLEX FORMATION BETWEEN HEAVY METAL CATIONS AND DIAZA CROWN ETHERS AND CRYPTANDS IN AQUEOUS SOLUTION

Abstract

Complexation of some heavy metal cations in aqueous solution by diaza crown ethers and cryptands has been studied using pH-metric titrations. In most cases, macrobicyclic cryptands form more stable complexes than diaza crown ethers. The size of the cavity aiso influences the stability of the complexes formed.     

MOLECULAR INTERACTIONS OF CARBOXYLATED URETHANE ACRYLATE IONOMERS IN LOW-POLARITY AND POLAR SOLVENTS

Carboxylated urethane acrylate ionomers that have a small number of ionic groups per chain were synthesized with varying the molecular weight of soft segment, the degree of ionization, and the sort of diisocyanate. The effect of intra-and intermolecular interactions on solution properties was studied by viscosity measurements in low-polarity and polar solvents. In a low-polarity solvent (1,4-dioxane), ionomers showed almost no intramolecular interaction at dilute concentration and a small degree of intermolecular interaction at high concentrations, resulting from a small number of ionic groups per chain. In a polar solvent (dimethylacetamide, DMAc), ionomers showed typical polyelectrolyte behavior, even though ionomers have a small number of ionic groups per chain. Intermolecular interaction caused by polyether soft segment, phenyl group, and hydrogen bond between urethane acrylate ionomer chains contributed to the increase of reduced viscosity at low concentration.     

分光光度法研究镧与间硝基偶氮氯膦(CPAmN)的络合物形成反应

本文研究了CPAmN试剂的特性、La-GPAmN络合物的组成和β-型络合物的生成条件,并测定了其积累稳定常数。     

THE EQUILIBRIA AND KINETICS OF THE COMPLEX FORMATION BETWEEN Fe(III) AND TARTARIC AND CITRIC ACIDS

Abstract

The equilibria and kinetics of formation of 1 : 1 iron(III) complexes with tartaric and citric acids have been studied in the pH range 1.0–2.0 in aqueous alcoholic perchlorate media. The equilibrium constants for the reactions Fe³⁺ +

H₄L^keq Complex + nH⁺ were obtained from spectrophotometric measurements in the wavelength range 360–420 nm. The values of K _eq determined at 20°, μ=1.0 M (water 100%), were 0.21 M with n=2 for tartaric and 0.0186 M² with n=3 for citric acid. The stoichiometry of the complex formation and the reaction sites of the ligands were discussed with reference to previous findings on ligands of related structures. The kinetics of the reactions were carried out by the stopped-flow technique. From the hydrogen ion dependence of the reaction rates it can be shown that complex formation occurs between FeOH²⁺ and differently protonated forms of the ligands. Forward rates for the different paths are consistent with an SN1 IP interaction in agreement with the Eigen mechanism; forward and reverse rate quotients enabled the evaluation of the equilibrium constants which agreed satisfactorily with the spectrophotometric ones. The effect of varying the solvent composition (water-alcohol) was discussed with reference to the reaction mechanism.     

ABSORPTION AND FLUORESCENCE SPECTRA OF CHLOROPHYLL-a IN POLAR SOLVENTS AS A FUNCTION OF TEMPERATURE

Abstract— Absorption and fluorescence spectra of chlorphyll-a in aqueous alcohol were determined as a function of temperature between 173° and 293°K. From a comparison of these spectra with ones obtained in pure methanol, it is suggested that changes in molecular association occur within aggregates of chlorophyll-a in aqueous-alcoholic solution induced by variation of the dielectric constant. The latter varies over a wide range in aqueous alcohol as a function of temperature.     

苯、甲苯与某些极性溶剂在293.15 K的过量体积

某些极性有机溶剂与烯烃、芳烃的特殊相互作用,是这些极性溶剂能够将烯烃、芳烃自烷烃中分离的基础。其分离的选择性决定于这种特殊相互作用。 L.J.Andrews认为腈类化合物、酮类化合物能与苯或苯的甲基衍生物生成电荷转移络合物,如苯与四氰基乙烯的络合物。R.F.Weimer和J.M.Prausnitz用紫外分光光度法测定过对-二甲苯与丙腈、丙酮、N-甲基吡咯烷酮等物的分子络合常数。我们也用分光光度法测定过某些芳烃与N-甲基吡咯烷酮的分子络合常数。     

ULTRAFILTRATION MEMBRANE FORMATION OF PES-C, PES AND PPESK POLYMERS WITH DIFFERENT SOLVENTS

Ultrafiltration membranes were prepared using phenolphthalein polyarylethersulfone (PES-C),polyethersulfone (PES) and poly(phthalazinone ether sulfone ketone) (PPESK) as polymers and NMP,DMAc,DMF and DMSO as solvents by immersion precipitation via phase inversion.Experimental data of thermodynamic properties of the polymer solutions and kinetic process of membrane formation were reported.For polymer solutions with good solvents,the sequence of the viscous flow activation energy (E_η) was coincident with ...     

INTERACTION BETWEEN TRINUCLEAR OXOCENTRED COORDINATION COMPOUNDS OF TRANSITION METALS AND ORGANIC SOLVENTS1

Abstract

A number of oxo-centred trinuclear complexes have been obtained, of general formula [M₃O(OOCR)₆L₃]X (R?H, CH₃; M?Cr(III), Fe(III); L=pyridine, 4-picoline; X?NO^? ₃, ClO^? ₄). The behaviour of these compounds in absolute methanol and in dimethylsulphoxide was investigated by the conductometric method. Dissociation constants of the complexes were determined. Molar conductivities and solvodynamic radii of the cations were also evaluated. It has been shown that the cations do not undergo solvation to any measurable extent.     

极性非质子溶剂与甲醇或1,2-二氯乙烷的汽液平衡

使用双沸点仪测定了丙酮、乙酸乙酯、对二氧六环、乙腈或三乙胺与甲醇或1,2→二氯乙烷以及二者混合物等十一组二元体系在99.3 kPa下的汽液平衡数据(T,x,p), 计算了有关体系的过量吉布斯自由能。结果表明, 六种非质子溶剂与甲醇组成的二元系GE>0; 乙腈或三乙胺与1,2-二氯乙烷组成的二元系GE>0, 而丙酮、乙酸乙酯或对二氧六环与1,2-二氯乙烷的二元混合物GE<0。从同种分子间或不同种分子间的缔合作用对上述结果进行了讨论。本文还在固定极性非质子溶剂(第三组分)物质的量浓度的条件下, 测定了非质子溶剂+1,2-二氯乙烷+甲醇三元混合物的汽液平衡数据, 考察了非质子溶剂的加入对甲醇+1,2-二氯乙烷二元系GE的影响。     

(聚酰胺-胺)树状大分子对甲氨蝶呤的复合和释放研究

以甲氨蝶呤(MTX)为模型药物,研究了PAMAM与MTX的复合及体外释放.1H-,13C-NMR数据表明MTX与PAMAM树状大分子形成复合物是由于MTX羧基和PAMAM树状大分子外端氨基之间的相互作用.该复合物在pH=7.4,10 mmol/L Tris-HCl中非常稳定,表现出明显的缓释效果.当溶液中的离子强度增加时,会破坏PAMAM-MTX复合物的稳定性,缓释作用部分或全部失去,说明PAMAM树状大分子与MTX之间的相互作用属于静电作用.UV测得每个G5.0 PAMAM、G4.0 PAMAM树状大分子分别能复合271、4个MTX分子.     

ADDUCT FORMATION BETWEEN BISCYCLOPENTADIENYL TITANIUMDIFLUORIDE AND BORON TRIFLUORIDE AND PHOSPHORUS PENTAFLUORIDE

Abstract

The reactions of organoplatinum cations have been investigated over the past few years in this laboratory.¹ As part of a general program, we recently tried to synthesize the biscyclopentadienyltitanium dication, Cp₂Ti²⁺ (where Cp =pentahaptocyclopentadienyl). Reaction of Cp₂TiCl₂ with two equivalents of AgBF₄ (or AgPF₆) in acetone gave, after filtering and evaporating the reaction solution, a red oil. Treatment of this red oil with methanol caused immediate precipitation of yellow Cp₂TiF₂. The isolation of Cp₂TiF₂ has been reported previously from reactions involving fluorine-containing reagents such as silver salts of CF₃S^?2, BF₄ ^?, PF₆ ^?, SbF₆ ^? and AsF₆ ^?3. Methanolysis of bis(cyclopentadienyl) (ethyl-3-ketobutyrato)titanium hexafluorophosphate also yields Cp₂TiF₂ ⁴. This sort of transfer of fluorine from counter-ion to metal has recently been observed in the reactions of metal bistetrafluoroborates (M =Co²⁺, Ni²⁺ and Cu²⁺) with triethylenediamine and quinuclidene⁵ in refluxing tetrahydrofurandimethoxypropane azeotrope. The products in these cases were the metal difluorides and BF₃ adducts of the strong nitrogen bases. The phenomenon is not confined to transition metals. (CH₃)₂SnF₂ is formed in the reaction of (CH₃)₂SnCl₂ with two equivalents of AgBF₄ or AgPF₆ in methanol.⁶     

稀土离子与硫氰酸根及硝酸根的络合作用

在25℃下,以2MNaClO₄维持水相的离子强度恒定,用离子交换法测定了除Ce和Pm以外的镧系元素及钇与CNS^-和NO₃^-的络合作用。用北京大学6912计算机处理了实验数据。结果表明:(1)RE³⁺与CNS^-的络合作用不大,当[CNS^-]≤1.5M时,主要以RECNS²⁺,RE(CNS)₂⁺及RE(CNS)₃三种络合物形式存在;镧系元素与CNS^-的络合度Y₍₁₎随原子序数Z的增大,总的趋向是增大,钇的Y₍₁₎值为最小。(2)RE²⁺与NO₂⁺的络合作用较弱,当[NO₂⁺]≤1.5M时,主要的络合物是RENO₃²⁺;各镧系元素与NO₃^-的Y₍₁₎随Z的增大,总的趋向是减小,钇的Y₍₁₎值最小。(3)在本实验中,稀土络合离子在树脂上的吸附量是可以忽略不计的。     

CHARACTERIZATION OF ION-PAIR FORMATION BETWEEN IONIZED INDOMETHACIN AND CATIONIC SURFACTANTS

The interactions between sodium indomethacin and chloride salts of four quaternary ammonium compounds were characterized. Investigations involved conductimetric studies at concentration regions wherein ion-pairs exist in equilibrium with the solution of participating ions. Iontophoresis was also utilized to investigate the phenomenon of ion-pairing. Characteristic of large molecules, extremely high levels of ion-pair association constants and low degrees of dissociation were obtained.