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101.
Gunnlaugsson T Leonard JP Sénéchal K Harte AJ 《Chemical communications (Cambridge, England)》2004,(7):782-783
The cationic cyclen based Eu(III)-phen conjugated 1.Eu was synthesised as a chemosensor for Cu(II), where the recognition in water at pH 7.4 gave rise to quenching of the Eu(III) luminescence and the formation of tetranuclear polymetallic Cu(II)-Eu(III) macrocyclic complexes in solution where Cu(II) was bound by three 1.Eu conjugates. 相似文献
102.
Gajewski JJ Bocian W Brichford NL Henderson JL 《The Journal of organic chemistry》2002,67(12):4236-4240
The competitive kinetics of additions of allyl to benzaldehyde-h and -d from allyltributyl tin, from diisopropyltartrylallyl boronate, and from allyl bromide and zinc dust in aqueous tetrahydrofuran have inverse secondary deuterium kinetic isotope effects, SDKIEs. These inverse SDKIEs are in contrast to the normal SDKIEs that were obtained with allyl lithium and allyl Grignard, suggesting rate-determining single-electron transfer in these cases. By various MO calculations the transition state for addition of allyl boronate occurs with substantial B-O bond formation and little C-C bond formation. The magnitudes of the SDKIEs with the other two allylating reagents, when compared with reasonable equilibrium isotope effects for the addition, suggest transition states with substantial C-C bond formation. 相似文献
103.
Joseph A. Connor Jose A. Martinho-Simoes Henry A. Skinner Mohammad T. Zafarani-Moattar 《Journal of organometallic chemistry》1979,179(3):331-356
Microcalorimetric measurements at elevated temperatures of the heats of thermal decomposition and iodination have led to values of the standard enthalpies of formation of the following crystalline compounds (values given in kJ mol?1) at 298K: [Cr(η6-1,3,5-C6H3(CH3)3)2] = (63±12); [Cr(η6-C6(CH3)6)2] : -(88±12); [Cr(1,2,3,4,4a,8a-η-C10H8)2] = (407±11); [Cr(CO)3(1,2,3,4,4a,8a-η-C10H8)] = -(258±8). Separate measurements by the vacuum sublimation microcalorimetric technique gave the following values for the enthalpy of sublimation at 298K (kJ mol?1) : [Cr(η6-1,3,5-C6H3(CH3)3)2] = (104±1); [Cr(η6-C6(CH3)6)2] = (119±4); [Cr(CO)3(1,2,3,4,4a,8a-η-C10H8)] = (107±3). From these and other data, the bond enthalpy contributions of the metal-ligand bonds in the gaseous metal complexes were evaluated as follows: [(η6-C6(CH3)6)-Cr] (155±7); [(η6-C6H3(CH3)3)-Cr] (151±6); [(1,2,3,4,4a, 8a-η-C10H8)-Cr](145±6) kJ mol?1]The question of the transferability of the enthalpy contributions of chromium—ligand bonds between organochronium complexes is discussed with aid of information from structural and spectroscopic investigation. The limitations of the procedure are defined.The thermodynamic data are used to discuss various substitution, redistribution and exchange reaction of Cr(η-arene)2 and [Cr(CO)3(η-arene)] compounds. 相似文献
104.
Keiper JS Behles JA Bucholz TL Simhan R DeSimone JM Lynn GW Wignall GD Melnichenko YB Frielinghaus H 《Langmuir : the ACS journal of surfaces and colloids》2004,20(4):1065-1072
Anionic phosphodiester surfactants, possessing either two fluorinated chains (F/F) or one hydrocarbon chain and one fluorinated chain (H/F), were synthesized and evaluated for solubility and self-assembly in liquid and supercritical carbon dioxide. Several surfactants, of both F/F and H/F types and having varied counterions, were found to be capable of solubilizing water-in-CO2 (W/C), via the formation of microemulsions, expanding upon the family of phosphate fluorosurfactants already found to stabilize W/C microemulsions. Small-angle neutron scatteringwas used to directly characterize the microemulsion particles at varied temperatures, pressures, and water loadings, revealing behavior consistent with previous results on W/C microemulsions. 相似文献
105.
This Letter describes the amination of 3-bromoisoxazoles by a nucleophilic aromatic substitution reaction. We have found 3-bromoisoxazoles to be inert to substitution under thermal conditions, however, the employment of phosphazene bases under microwave irradiation facilitates the amination process and allows the corresponding 3-aminoisoxazoles to be isolated in moderate yield. 相似文献
106.
The displacements of the methyl substituents away from the metal and out of the cyclopentadienyl ring plane are compared in sterically crowded (C(5)Me(5))(3)M complexes vs sterically normal f-element complexes in an attempt to evaluate the utility of this parameter in predicting unusual (C(5)Me(5))(1-) ring reactivity. The out-of-plane displacements of 16 sterically crowded tris(cyclopentadienyl) complexes of general formula (C(5)Me(5))(3)M, (C(5)Me(4)R)(3)M (R = Et, (i)Pr, (t)()Bu, SiMe(3)), (C(5)Me(5))(3)MX (X = anion), and (C(5)Me(5))(3)ML (L = neutral ligand) are compared with [(C(5)Me(5))(2)U](2)(C(6)H(6)), (C(5)Me(5))(2)Sm(PC(4)H(2)(t)Bu(2)), and 33 representative examples of f-element bis(cyclopentadienyl) complexes with normal cyclopentadienyl behavior and coordination numbers ranging from 6 to 10. In general, the methyl displacement values of sterically crowded complexes overlap with those in the other complexes, which demonstrates that the basis of the structural distortions is complex. However, if the most extreme out-of-plane displacement in each of the sterically crowded complexes is examined vs the analogous maximum out-of-plane displacement in less crowded systems, there appears to be a basis for predicting cyclopentadienyl reactivity. 相似文献
107.
Novel bifunctional conjugates 1-3, with varying polymethylene spacer groups, were synthesized, and their DNA interactions have been investigated by various biophysical techniques. The absorption spectra of these systems showed bands in the regions of 300-375 and 375-475 nm, corresponding to acridine and acridinium chromophores, respectively. When compared to 1 (Phi(f) = 0.25), bifunctional derivatives 2 and 3 exhibited quantitative fluorescence yields (Phi(f) = 0.91 and 0.98) and long lifetimes (tau = 38.9 and 33.2 ns). The significant quenching of fluorescence and lifetimes observed in the case of 1 is attributed to intramolecular electron transfer from the excited state of the acridine chromophore to the acridinium moiety. DNA-binding studies through spectroscopic investigations, viscosity, and thermal denaturation temperature measurements indicate that these systems interact with DNA preferentially through intercalation of the acridinium chromophore and exhibit significant DNA association constants (K(DNA) = 10(5)-10(7) M(-1)). Compound 1 exhibits chromophore-selective electron-transfer reactions and DNA binding, wherein only the acridinium moiety of 1 interacts with DNA, whereas optical properties of the acridine chromophore remain unperturbed. Among bifunctional derivatives 2 and 3, the former undergoes DNA mono-intercalation, whereas the latter exhibits bis-intercalation; however both of them interact through mono-intercalation at higher ionic strength. Results of these investigations demonstrate that these novel water-soluble systems, which exhibit quantitative fluorescence yields, chromophore-selective electron transfer, and DNA intercalation, can have potential use as probes in biological applications. 相似文献
108.
Adams CJ Bowen LE Humphrey MG Morrall JP Samoc M Yellowlees LJ 《Dalton transactions (Cambridge, England : 2003)》2004,(24):4130-4138
Compounds of the form Ru(X2bipy)(PPh3)2(-C triple bond CC6H4NO2-p)2(X2bipy = 4,4'-X(2)-2,2'-bipyridine, X = Me 3a, Br 3b, I 3c) have been synthesised from the mono-alkynyl precursors Ru(X2bipy)(PPh3)2(-C triple bond CC6H4NO2-p)Cl (X = Me 2a, Br 2b, I 2c); the former are the first ruthenium bis-alkynyl compounds that also contain a bipyridyl ligand. Spectroelectrochemical investigation of 3a shows that the metal is readily oxidised to form the ruthenium(III) compound 3a+, and will also undergo a single-electron reduction at each nitro group to form 3a2-. ESR and UV/visible spectra of these redox congeners are presented. We also report the synthesis of [Ru(Me2bipy)(PPh3)2(-C triple bond CBut)(N triple bond N)][PF6] during the attempted synthesis of Ru(Me2bipy)(PPh3)2(-C triple bond CBut)2, and report its X-ray crystal structure and IR spectrum. X-Ray crystal structures of 3b and 3c(as two different solvates) are presented, and the nature of the intermolecular interactions seen therein is discussed. Z-Scan measurements on Ru(Me2bipy)(PPh3)2(-C triple bond CR)Cl (R = C6H4NO2-p2a, But, Ph, C6H4Me) are also reported, and show that Ru(Me2bipy)(PPh3)2(-C triple bond CR)Cl (R = C6H4NO2-p2a, Ph) exhibit moderate third-order non-linearities. 相似文献
109.
A. Joseph 《International journal of quantum chemistry》1967,1(5):615-629
A general method is developed for determining the exact number of bound states for a given potential in a space of N dimensions (N ≧ 2). This is applied to a central potential of the form where λ, r0, α are arbitrary positive numbers, and for which analytical solutions are obtained. Some properties of the degeneracy in the energy levels, with respect to the orbital angular momentum l, are also discussed. 相似文献
110.
‘Bare’ FeO+ reacts in the gas phase with norbornane with collision efficiency, and the most prominent cationic products correspond to [FeC5H6]+ (32%), [FeC7H8]+ (19%), [FeC3H6O]+ (19%) and [FeC6H6]+ (14%), which are structurally characterized by ligand exchange as well as collision-induced dissociation experiments. Circumstantial evidence is provided which indicates that the complexes [FeC5H6]+, [FeC7H8]+, and [FeC6H6]+ originate from an Fe(norbornene)+ intermediate which itself is formed by elimination of H2O from the [FeO(norbornane)]+ encounter complex. Although the reactions are preceded and/or accompanied by partial H/D exchange, the isotope distribution in the productions clearly points to a preferential endo-attack of bare FeO+, with an endo/exo-ratio of ca. 10.3 and kinetic isotope effects kH/kD for the endo-abstraction of 2.4 and of 7.7 for approaching an exo-C? H bond. The preferred endo-approach of bicyclo[2.2.1]heptane by ‘bare’ FeO+ is in distinct contrast to the P-450-mediated or the iron(III)porphyrin-catalyzed hydroxylation of this substrate which favor reactions at the exo-face. 相似文献