已烯自由基阳离子的密度泛函理论研究

使用密度泛函理论B3LYP方法和6-31G(d,p),6-31+G(d,p),6-311G(d,p)及6- 311+G(d,p)基组,分别对1-C_6H_(12)~+,2-C_6H_(12)~+和3-C_6H_(12)~+的各种构 象进行了几何构型优化,并在B3LYP/6-311G(d,p)水平上进行了频率分析计算,在 各优化构型上,使用B3LYP和MP2(full)方法进行了超精细结构的计算。计算的3- C_6H_(12)~+的超精细偶合常数比以往的计算结果更好;1-C_6H_(12)~+和2-C_6H_ (12)~+的超精细偶合常数目前尚无实验数据报道,本计算预言了它们的超精细偶合 常数和最稳定构型。     

Correlation of Solution and Gas Phase Complexation Assessed by Electrospray Ionization Mass Spectrometry: Application to One-, Two-, and Three-Ring Macrocycles

Electrospray ionization mass spectrometry (ESI-MS) was used to probe multiple cation complexation by C(12)H(25)(CH(2))(12)(CH(2))(12)C(12)H(25), 2, and <18N>CH(2)C(6)H(4)CH(2), 3. Complexation of two cations (2Na(+), 2 K(+), or Na(+) and K(+)) by 3 and three cations by 2 (3 Na(+), 3 K(+), and mixtures) as well as mixed proton-metallic cation complexes of both were observed. The K(+)/Na(+) cation-binding selectivity of 18-crown-6 was studied by ESI-MS of a methanol solution, and the selectivity profile was favorably compared with data obtained previously by ion-selective electrode techniques in the same solvent.     

Heavier alkali metal complexes of 2-phenylamidopyridine: an X-ray crystallographic and theoretical study of a structurally diverse series of crown ether adducts

Complexes of the anion of the secondary amine 2-phenylaminopyridine (LH) with the heavier alkali metals Na-Cs have been prepared in the presence of various macrocyclic polyether crowns [12-crown-4 (12C4), 15-crown-5 (15C5), and 18-crown-6 (18C6)], which coordinate to the metal ions in all cases. Depending on the combination of alkali metal and crown, the products include separated ion pairs [(crown)(2)M](+)L(-)(12C4/Na, 15C5/K, 15C5/Rb, 15C5/Cs) and contact-ion-pair neutral molecules [(crown)ML](15C5/Na, 18C6/Na, 18C6/K, 18C6/Rb) in which L(-) acts as a bidentate ligand. [((12C4)KL)(2)] is a dimer in which the amido and pyridine N atoms of two ligands bridge the metal ions, while [((18C6)KL(2)K)([infinity])] is a chain polymer with crown O and pyridyl N atoms acting as bridges in corner-sharing KOKN four-membered rings and may be regarded as a potassium potassate complex. [((18C6)Cs(2)L(2))([infinity])] is also polymeric, with a basic arrangement like that of [((12C4)KL)(2)], but with each 18C6 ligand mu-kappa6:kappa6 to two metal centres, generating the polymer. Although most of the [(crown)(2)M](+) sandwich cations have essentially parallel crown ligands, [(12C4)(2)Rb](+) is markedly bent, both in the complex incorporating THF as an additional ligand and in the THF-free complex, where two of these cations form a centrosymmetric dimer through two bridging oxygen atoms; DFT calculations indicate that the bending is inherent, thus enabling the coordination by an extra oxygen atom rather than being a consequence of this coordination. Attempts to isolate the caesium 12C4 derivative were unsuccessful. The compounds have been characterized by NMR spectroscopy, CHN microanalysis and, in most cases, X-ray crystallography.     

C6F5X＋（X=Cl,Br,I,CH3）离子的理论研究

用DFT B3LYP方法及6-311G（d,p）,6-311＋G（d,p）和LanL2dz基组,对C6F5X＋（X=Cl,Br,I,CH3）阳离子做了理论研究,优化了它们的电子基态的构型,计算了对应分子的垂直电离势（VIP）和绝热电离势（AIP）.结果表明四种离子的构型的对称点群和对应分子相同,但构型参数有明显差别.B...     

Theoretical study of the structures of [M(18C6)](HFA)2 complexes (M = Ba,Sr, Pb,Cd, Mn; 18C6 = 18-crown-6; HFA = hexafluoroacetylacetonate anion)

The structures of the [M(18C6)]²⁺ cations (M = Ba, Sr, Pb, Cd, Mn) and their salts [M(18C6)](HFA)₂ and [M(18C6)](NO₃)₂ have been calculated by the density functional theory method (in the B3LYP/6-311++G** + LanL2Dz approximation). Upon geometry optimization, the gas-phase structures of compounds of different composition have been calculated; for them, the strength of binding of the central cation to the crown ether (18C6) and the degree of structural similarity have been evaluated. The structure of the [NH₄(18C6)]⁺ cation identified in a practical synthesis has also been considered. For metal cations acting as a central atom, NH ₄ ⁺ and [M(18C6)]²⁺ complex cations, as well as for intermediate and ultimate products [M(18C6)](NO₃)₂ and [M(18C6)](HFA)₂ (M = Ba, Sr, Pb, Cd, Mn), the electronic chemical potential and Pearson hardness, which enables the consideration of the propensity of various reagents to interact with each other in terms of the empirical HSAB principle (hard with hard and soft with soft), have been evaluated. Comparison of the estimates with the properties of the synthesized compounds with M = Ba, Sr, and Pb makes it possible to preliminarily verify the applicability of this principle to the systems under consideration and predict some properties of isostructural analogues important in the search for methods of synthesis of [M(18C6)](HFA)₂, where M = Cd and Mn. The possibility of establishing a correlation between the electron density of the system, stability, and hydrolytic activity of complexes has been shown.     

Improved synthesis of isogranulatimide, a G2 checkpoint inhibitor. Syntheses Of didemnimide C, isodidemnimide A, neodidemnimide A, 17-methylgranulatimide, and isogranulatimides A-C

A concise, improved synthesis of isogranulatimide (6), a naturally occurring substance with G2 checkpoint inhibition activity, is described. Also reported are the syntheses of didemnimide C (18), isodidemnimide A (24), neodidemnimide A (36), 17-methylgranulatimide (9), and isogranulatimides A (10), B (11), and C (12). Compounds 9-12, congeners of isogranulatimide (6), are now available for biological evaluation.     

6-Oxy-(acetyl ethylenediamine) fluorescein, a novel fluorescent derivatization reagent for carboxylic acids and its application in HPLC

A novel fluorescent derivatization reagent for carboxylic acids, 6-oxy-(acetyl ethylenediamine) fluorescein (AEF), was well designed, synthesized, and applied to HPLC. The derivatization reaction with 12 fatty acids, including n-valeric acid (C5), n-hexanoic acid (C6), n-heptanoic acid (C7), n-octanoic acid (C8), n-nonanoic acid (C9), n-decanoic acid (C10), lauric acid (C12), myristic acid (C14), palmitic acid (C16), stearic acid (C18), oleic acid (C18:1), and linoleic acid (C18:2), was completed at 55 degrees C within 40 min. The derivatives of fatty acids were separated on a C18 RP column and detected by fluorescence detection. The LODs attained were 0.4-1.2 nM (S/N of 3). It has been demonstrated that AEF is a prominent derivatization reagent for carboxylic acids which is suitable for HPLC.     

Spectral properties of rhodamine 6G in smectite dispersions: effect of the monovalent cations

Montmorillonite monoionic forms with alkali metal and NH(4)(+)-cations were prepared by ion exchange. The hydration properties and binding of the ions to montmorillonite surface and the swelling properties of the mineral specimens were analyzed. Whereas Na(+)- and Li(+)-ions were fully hydrated over a large range of conditions, large size K(+), NH(4)(+), and mainly Rb(+) and Cs(+) ions were apt to bind directly to the oxygen atoms on the mineral surface. The forms with large ions exhibited reduced hydration and swelling and the absence of macroscopic swelling of the respective aqueous colloids. The interaction of laser dye rhodamine 6G (R6G) in montmorillonite colloids was investigated by absorption and steady-state fluorescence spectroscopies. Significant effects of the properties of both the inorganic ions and swelling properties of colloidal dispersions on R6G molecular aggregation were observed. Large amounts of the molecular aggregates were formed in the colloids of Na(+)- and Li(+)-montmorillonites. The aggregates absorbed light at significantly lower wavelengths (~460 nm) with respect to the light absorption by monomers (535 nm). Fluorescence spectroscopy provided a key evidence for the assignment of the type of the aggregates: The emission of the aggregates at relatively low energies proved these assemblies are rather a mixed H-/J-type than ideal H-aggregates. The presence of parent inorganic cations of larger size led to a significant lowering of the amount of the R6G aggregates in favor of the monomers. Investigations of the evolution of the dye aggregation with time indicated basic features of dye aggregation reaction: The size of parent inorganic ions did not affect the reaction mechanism, but rather limited the extent of the reaction. Probably the forms with large inorganic ions, such as Rb(+) and Cs(+), did not provide sufficient surface for the formation of the large size assemblies of the dye. This property can be explained in terms of strong association of the large alkali metal ions to clay mineral surface, as well as to reduced swelling in the colloidal systems of respective forms.     

Theoretical study of the structure and water affinity of [M(18C6)(HFA)<Subscript>2</Subscript>] complexes for M = Zn,Cu, Hg,Co, Ni,and Pt

The structures of the [M(18C6)]²⁺ cations, where M = Zn, Cu, Hg, Ni, Co, and Pt, and cis- and trans-[M(18C6)(HFA)₂]/[M(18C6)(NO₃)₂] molecules in the gas phase have been calculated by the density functional theory method in the B3LYP/6-31G*//6-311++G** + LanL2Dz approximation. Geometry optimization has been performed, and the strength of binding of the central cation to the crown ether (18C6) and the degree of structural similarity of the [M(18C6)(HFA)₂] compounds for different central atoms M have been evaluated. For all [M(18C6)(NO₃)₂]/[M(18C6)(HFA)₂] molecules (M = Zn, Cu, Hg, Ni, Co, Pt), the vertical ionization potential and the vertical electron affinity have been calculated. These parameters are of interest for analysis of the stability of volatile compounds [M(18C6)(HFA)₂] to donor–acceptor interactions with other components of the gas phase, for example, with water vapor, which is usually a Lewis base with respect to the systems in question and can donate electron density in the course of complexation with the central atom. The propensity of the [M(18C6)(NO₃)₂]/[M(18C6)(HFA)₂] molecules to react with water is considered for a wider range of metals M²⁺ = Ba²⁺, Sr²⁺, Pb²⁺, Mn²⁺, Cd²⁺, Zn²⁺, Cu²⁺, Hg²⁺, Co²⁺, Ni²⁺, and Pt²⁺, with taking into account the degree of matching between the ionic radii of M²⁺ cations and the 18C6 cavity size.     

Interactions of metal ions with monoaza crown ethers A15C5 and A18C6 carrying dansyl fluorophore as pendant in acetonitrile solution

The influence of metal cations Li(+), Na(+), K(+), Cs(+), Mg(2+), Ca(2+), Sr(2+), Ba(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Pb(2+) and Al(3+) on the spectroscopic properties of the dansyl (1-dimethylaminonaphthalene-5-sulfonyl) group covalently linked to monoaza crown ethers 1-aza-15-crown-5 (1,4,7,10,-tetraoxa-13-azacyclopentadecane) (A15C5) and 1-aza-crown-6 (1,4,7,10,13-pentaoxa-16-azacyclooctadecane) (A18C6) was investigated by means of absorption and emission spectrophotometry. Interaction of the alkali metal ions with both fluoroionophores is weak, while alkaline earth metal ions interact strongly causing 50 and 85% quenching of dansyl fluorescence of N-(5-dimethylamine-1-naphthalenesulfonylo)-1,4,7,10,-tetraoxa-13-azacyclopentadecane (A15C5-Dns) and N-(5-dimethylamine-1-naphthalenesulfonylo)-1,4,7,10,13-pentaoxa-16-azacyclooctadecane (A18C6-Dns), respectively. The Cu(2+), Pb(2+) and Al(3+) cations interact very strongly with dansyl chromophore, causing a major change in absorption spectrum of the chromophore and forming non-fluorescent complexes. The Co(2+), Ni(2+), Zn(2+), Mg(2+) cations interact moderately with both fluoroionophores causing quenching of dansyl fluorescence by several percent only.     

氟代乙烯阳离子的理论研究

用B3LYP和MP2方法及6-31G(d, p)、6-31＋G(d, p)、6-311G(d, p)和6-311＋G(d, p) 基组，对六种氟代乙烯阳离子做了理论研究，优化了它们的基电子态的结构，计算了对应分子的垂直电离势（VIP）和绝热电离势(AIP).结果表明，与具有非平面结构的乙烯阳离子不同，六种氟代乙烯阳离子都只具有平面结构；与分子结构相比，离子结构的C－C键增长， C－F键缩短， CCF键角变小. 自然布居分析计算表明，这些离子的正电荷主要分布在与F原子相连的C原子和各H原子上. B3LYP/6-311＋G(d, p) 级别上计算的各分子的VIP和AIP值和实验值符合得很好. 使用含弥散基函数的基集可以明显提高这类分子的电离势的计算精度.     

Study of Bulk Membrane Transport of Some Heavy Metal Cations Using Three Macrocyclic Ligands Containing Oxygen and Nitrogen Heteroatoms

The transport experiments of Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Ag⁺ and Pb²⁺ metal cations were carried out by dibenzo-18-crown-6 (DB18C6), dibenzyl-diaza-18-crown-6 (Dibenzyl-diaza-18C6) and di-tert-butyl-dibenzo-18-crown-6 (Di-tert-butyl-DB18C6) using chloroform (CHCl₃), 1,2-dichloroethane (1,2-DCE) and nitrobenzene (NB) organic solvents as liquid membranes. The source phase contained equimolar concentration of these metal cations and the source and receiving phases being buffered at pH=5 and pH=3, respectively. The obtained results show that the selectivity and the efficiency of transport for these heavy metal cations change with the nature of the ligand and also the organic solvents, which were used as liquid membranes in these experiments. A good selectivity was observed for silver (I) ion by dibenzyl-diaza-18C6 in all membrane systems. Dibenzo-18C6 and di-tert-butyl-DB18C6 showed the highest transport efficiency for cobalt (II) ion. The effect of stearic acid on transport efficiency was also investigated and the results show that the efficiency of transport of the heavy metal cations increases in the presence of this organic acid.     

Conductivities, volumes, fluorescence, and aggregation behavior of ionic liquids [C4mim][BF4] and [C(n)mim]Br (n = 4, 6, 8, 10, 12) in aqueous solutions

Densities, conductivities, and polarity indexes of pyrene for aqueous solutions of a series of ionic liquids [C(n)mim]Br (n = 4, 6, 8, 10, 12) and [C4mim][BF4] have been determined at 298.15 K as a function of ionic liquid concentrations. It was shown that possible aggregation appeared for the ionic liquids in aqueous solutions except for [C4mim]Br. The critical aggregation concentration (CAC) of the ionic liquids, the ionization degree of aggregates (beta), the standard Gibbs energy of aggregation (Delta G(m)(o)), the limiting molar conductivity (Lambda(m)(o)), and the standard partial molar volume (V(m)(o)) for the ionic liquids were derived from the experimental data. The dependence of the CAC, Delta G(m)(o), Lambda(m)(o), and V(m)(o) on the length of the alkyl chain of the cations was examined. It was further suggested from volumetric data that a micelle was formed for [C8mim]Br, [C10mim]Br, and [C12mim]Br in aqueous solutions. Their apparent molar volumes at the critical micelle concentration (V Phi,CMC), apparent molar volumes in the micelle phase (V(Phi)(mic)), and the change of their apparent molar volume upon micellization (Delta V Phi,m) were calculated by application of the pseudophase model of micellization. In addition, the average aggregation number of [C(n)mim]Br (n = 8, 10, 12) has been determined by the steady-state fluorescence quenching technique, and predicted from a simple geometrical mode. It is found that the experimental values are in good agreement with the predicted ones.     

Monodisperse,submicrometer-scale platinum colloidal spheres with high electrocatalytic activity

Monodisperse, submicrometer-scale platinum (Pt) colloidal spheres were prepared through a simple direct chemical reduction of p-phenylenediamine (PPD)-chloroplatinic acid (H₂PtCl₆) coordination polymer colloids. It was found that the prepared Pt colloids had the similar size and morphology with their coordination polymer precursors, and the prepared Pt colloids with rough surfaces were three-dimensional (3D) structured assemblies of high-density small Pt nanoparticles. The electrochemical experiments confirmed that the prepared Pt colloids possessed a high electrocatalytic activity towards mainly four-electron reduction of dioxygen to water, making the prepared Pt colloids potential candidates for the efficient cathode material in fuel cells.     

Cationization versus surface activity--the effect on electrospray ionization

Ethoxylated fatty alcohols, C(12)E(1), C(12)E(2), C(18)E(1) and C(18)E(2), were studied by electrospray ionization mass spectrometry (E is the ethoxylene unit OCH(2)CH(2)). For compounds containing two ethoxylene units, which form quite stable adducts with sodium cation, the abundances of [M + Na](+) ions were not affected by alkyl chain, so the hydrophobic effect was not observed. For the compounds containing one ethoxylene unit, forming rather unstable adducts with sodium, the hydrophobic effect was clearly seen since the [C(18)E(1) + Na](+) ion was more abundant than the [C(12)E(1) + Na](+) ion. Two ethoxylene units are not able to form stable adducts with potassium cations, therefore the hydrophobic effect was observed for the [C(12)E(2) + K](+) and [C(18)E(2) + Na](+) ions, the latter being more abundant than the former. For lithium cation adducts with C(12)E(1) and C(18)E(1), the hydrophobic effect was observed, but was less manifested than for sodium cations since lithium adducts are more stable than sodium ones. C(18)E(1) and C(18)E(2) gave more intense signals at higher cone voltage values than C(12)E(1) and C(12)E(2), respectively. However, this is not related to the hydrophobic effect but to the collisions being less effective for the former.     

Thermochromic Properties of Silver Colloids Embedded in SiO2 Gels

By using the sol-gel process, colloids are prepared by the spontaneous reduction of silver ions, where the presence or absence of ethanol plays an important role. Thermochromic properties are observed in these gels in the temperature range between 15°C and 150°C. In the UV-Vis region the transmission spectrum red shift of the cut-off is employed to study these properties as a function of the temperature; a shift from 300 to 750 nm is observed. Originally, a broad shoulder centered at 435 nm is seen in gels prepared in the absence of ethanol and at 425 nm with ethanol, corresponding to surface plasmon resonances of the small silver particles in the colloids. These particles are responsible for the various colors observed in the gels. Additionally, the influence of temperature on the color stability, as well as on the influence shown by ethanol on the rate of displacement of the transmission cut-off wavelength, are studied.     

含嘧啶环的双冠醚 V.双冠醚为载体的碱金属离子选择性电极的研究

本文报道由５－硝基－６－三氟甲基嘧啶环桥联苯并－１２－冠－４、苯并－１５－冠－５和苯并－１８－冠－６的三种新的双冠醚的合成。用它们作为载体分别制成钠、钾和铯离子选择性电极，测定了电极的响应功能、选择性系数和适用的ｐＨ范围。结果表明三种电极都有较好的性能。     

聚冠醚的合成和性质——Ⅵ.聚冠醚为载体的碱金属离子选择性电极

本文报道以含有12-冠-4、15-冠-5和18-冠-6结构单元的双酚A型聚冠醚为载体的钠、钾和铯离子选择性电极的制备及电极响应特性的研究。结果表明三种电极都有较好的Nernstian响应特性和对碱金属及碱土金属的良好选择性。     

New copolymer gels based on <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethylacrylamide and crown-containing allyl derivative of 1,8-naphthalimide as optical sensors for metal cations in an organic medium

New copolymer gels bases on N,N-dimethylacrylamide and a crown-containing allyl derivative of 1,8-naphthalimide showing intense visible fluorescence have been prepared. The effect of metal cations on the optical properties of the fluorescent monomer and its copolymer gels has been studied. These gels have been found to exhibit optical response selectivity with respect to binding of alkaline-earth metals in an acetonitrile medium.     

含嘧啶环的双冠醚——V.双冠醚为载体的碱金属离子选择性电极的研究

本文报道由5-硝基-6-三氟甲基嘧啶环桥联苯并-12-冠-4、苯并-15-冠-5和苯并-18-冠-6的三种新的双冠醚的合成。用它们作为载体分别制成钠、钾和铯离子选择性电极，测定了电极的响应功能、选择性系数和适用的pH范围。结果表明三种电极都有较好的性能。