WEAK COMPLEX FORMATION BETWEEN PYRENE AND POLAR SOLVENTS

Abstract— Evidence of complex formation between pyrene and polar solvent molecules has been obtained by monitoring the S₁,← S₀ and S₂← S₀ absorption spectra of pyrene. The solvents employed are propionitrile, valeronitrile, dichloromethane, and dioxane. The stabilization energy is found to be small relative to general hydrogen bond energies, but somewhat high relative to the Boltzmann energy. These are in good accord with the findings of Lianos and Georghiou [ Photochem. Photobiol. 30 ,355 (1979)] that pyrene forms 1:1 molecular complexes with several dipolar solvents in the ground state.     

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.     

丙酮肟与某些芳烃相互作用的~1H核磁共振研究

Hatton和Richards通过对酰胺分子的~1H NMR谱溶剂效应的研究,提出了DMF与苯生成分子络合物的模型.如果络合物按1:1生成,那么将出现一个“饱和点”,在这点上甲基的芳香溶剂诱导位移(ASIS)的变化趋势或程度将出现一个明显的变化,事实上随着苯的摩尔分数从0到1逐渐增加时,化学位移总是有规则的逐渐移向高场.这就显示了分子络合物观点的局限性.它能被一些研究者所支持和接受,是因为它能够解释两个甲基共振峰先重合而后又分离的现象.     

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.     

关于吖啶氮氧化物与烃、醇、酮等之间的光化夺氢反应中的自由基的研究

有关吖啶及其某些衍生物在亲核加成反应中生成的各种自由基或离子基,曾由J.W.Happ等人予以研究^[1],吖啶本身与某些化合物之间的光化夺氢反应也曾被研究过^[2],而吖啶氮氧化物及其衍生物与烃类等化合物之间的光化夺氢反应研究,则尚未见文献报导。我们用吖啶氮氧化物、9-氯代吖啶氮氧化物和9-氰基吖啶氮氧化物分别与包括环烯烃、芳烃、烷烃、醇及羰基化物在内的15种化合物进行光化学反应,用ESR技术检出了很强而又相当稳定的氮氧自由基信号。     

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.     

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 RELATIONSHIP BETWEEN CARCINOGENIC ACTIVITIES OF POLYCYCLIC AROMATIC HYDROCARBONS AND THEIR SINGLET, TRIPLET, AND SINGLET-TRIPLET SPLITTING ENERGIES AND PHOSPHORESCENCE LIFETIMES

Abstract— The energies of the lowest excited singlet, E_s, and triplet, E_t, states, and singlet-triplet splitting energies, ΔE_s,t, were determined on 18 carcinogenic and 31 noncarcinogenic polycyclic aromatics. A highly significant correlation was found between carcinogenic activity and the energy of the excited singlet state. Compounds with an E_s < 312 kJ/mol were 4.8 times more likely to be carcinogens than those compounds with E_s 312 kJ/mol (P= 0.015). Compounds whose singlet energies fell within the narrow range of 297 ≤E_s≤ 310 kJ/mol were 22.8 times more likely to be carcinogens than those compounds which fell outside this range (P= 0.00006). A significant correlation between carcinogenic activity and E_t energies was not found, while the correlation involving ΔE_s,t energies was intermediate between the E_s and E_t correlations. The phosphorescence lifetimes, τ_p, of the 18 carcinogenic aromatics and 27 of the noncarcinogenic aromatip were determined, and were shown not to be correlated with carcinogenic activity. When either the E_t or ΔE_s,t energies were plotted as a function of E_s it was found that the carcinogens tended to form in an elliptical cluster. Compounds whose E_s and E_t energies placed them within the ellipse were 9.7 times more likely to be carcinogens than those compounds which fell outside the ellipse (P= 0.002), while with the E_s, ΔE_s,t ellipse, compounds which fell inside were 20.6 times more likely to be carcinogens than those which fell outside (P= 0.0004). E_s, E_t, ΔE_s,t and τ_p values were also determined on 12 carcinogenic and 4 noncarcinogenic alkyl substituted benz[a]anthracenes. There was no significant difference between the carcinogens and noncarcinogens and the “elliptical” correlation predicted both the carcinogens and noncarcinogens to be carcinogenic. The results suggest that either some property(ies) of the lowest excited singlet state, but not its energy, or some molecular property(ies) which runs parallel to singlet state energies may be important in determining carcinogenic activity in polycyclic aromatics.     

SOLUBILITIES OF POLYCYCLIC AROMATIC HYDROCARBONS AND DI-REGION THEORY

By using the relationship equation of Partition coefficients with water solubilities for polycyclic aromatic hydrocarbons (PAHs), we have estimated the solubilities of PAHs. In addition the high-performance liquid chromatograph (HPLC) method has been used for the indirect determination of solubilities of PAHs. t3ased on the di-region theory, We have studied the relationship of the solubilities of PAHs with carcinogenicity and introduced the solubility parameter into the di-region theory equation. The calculated carcinogenicity of PAHs from the obtained equation shows little difference from that calculated from Dai Qianhuan's equation.     

THE MEDIUM EFFECTS IN THE SULPHONATION OF POLYCYCLIC AROMATIC HYDROCARBONS

Abstract

Both the relative reactivities and the initial isomer distributions in the sulphonation of polycyclic hydrocarbons were found to be strongly dependent on the composition of reaction medium.     

HYDROGEN BONDING BETWEEN TERTIARY PHOSPHINES AND ALCOHOLS

Abstract

The hydrogen bond between several alcohols, in particular benzyl alcohol and isopropanol, as donors, and a number of tertiary phosphines, as well as a smaller number of tertiary arsines, as acceptors was investigated by means of ir spectroscopy in the temperature range +40° to -20°C. Toluene was used as a solvent. The equilibrium constant K, the hydrogen bond enthalpy -ΔH and the entropy -ΔS were determined. The equilibrium constants as well as the -ΔH values are essentially dependent on the basicity of the phosphines. There is no evidence of any steric influence. In the systems with aliphatic phosphines, the highest equilibrium constants are about 20, the lowest values are near unity. Aromatic phosphines possess a lower affinity of interaction with the alcohols. -ΔH varies for the different systems between 1.2 and 3.5 kcalμmole^?1. Investigating the acceptor power of arsines we found both K and -ΔH one order of magnitude lower than in the case of phosphines.     

TRIPLET STATES OF POLYCYCLIC AROMATIC HYDROCARBONS IN FLUID SOLUTION AND IN THE SOLID STATE

Abstract— –Triplet states of several large polycyclic aromatic hydrocarbons together with their lifetimes have been determined both in fluid solution and in the solid state using a spectrophoto-metric technique.
Excited states and lifetimes of some solid charge transfer complexes between the hydrocarbons and chloranil have been examined.
The assignment of the ¹ B _b states of some of the hydrocarbons have been made from the energies of the triplet states.     

二环戊二烯基钛烴氧基衍生物的合成和性能研究

二环戊二烯基二氯化钛与脂肪醇的反应是非常复杂的,由于反应体系不同,所得的产物也不同,且产物又不稳定^[1-3]。     

云南泥炭和褐煤中的多环芳烃

本文研究云南宝秀盆地一个钻孔不同深度的泥炭和褐煤抽出物芳烃馏分中多环芳烃的组成。用GC和GC/MS鉴别了它们的组份,结果表明,从双环和三环单芳构化、双芳构化、三芳构化到四环双芳构化、三芳构化及四芳构化和五环单、双芳构化、三芳构化、四芳构化以及C环开裂的萜类化合物均有不同含量的存在,这说明在煤化过程早期芳构化就进行到相当的深度,也说明云南陆源高等植物,尤其是喜温树类的造煤物种为宝秀盆地提供了特殊的芳构化有机组成系列。     

二烷基苯胺在饱和烷烃中对蒽和芘的荧光淬灭

研究了1,3-双(N-苯基-N-甲胺基)丙烷(DMA-AMD)、N-甲基-N-乙基苯胺(MEA)和二甲基苯胺(DMA)在正戊烷、甲基环己烷和正十六烷中对蒽和芘的荧光淬灭。荧光淬灭的同时有相应的激基复合物形成。发现DMA-AMD是一种比MEA或DMA都更为有效的淬灭剂,但生成的激基复合物的荧光效率很低。结果可用DMA-AMD内的另一个苯胺基与激基复合物产生分子内的淬灭来说明。这些苯胺的双分子淬灭速度常数取决于溶剂的粘度,而且在粘稠的烷烃中可以超过理论上扩散控制的限度。     

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.     

分光光度法测N-甲基吡咯烷酮与某些C8芳烃的分子络合常数

用分光光度法以正己烷、环己烷作稀释剂在紫外区测定N-甲基吡咯烷酮与苯乙烯、邻二甲苯、间二甲苯、对二甲苯的1:4络合常数K_c,此常数可用以定性地表示弱化学作用的强度。