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151.
152.
Dr. Manuel Tropiano Dr. Octavia A. Blackburn James A. Tilney Leila R. Hill Dr. Matteo P. Placidi Dr. Rebecca J. Aarons Dr. Daniel Sykes Dr. Michael W. Jones Dr. Alan M. Kenwright Dr. John S. Snaith Dr. Thomas Just Sørensen Prof. Dr. Stephen Faulkner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(49):16566-16571
A study of the anion‐binding properties of three structurally related lanthanide complexes, which all contain chemically identical anion‐binding motifs, has revealed dramatic differences in their anion affinity. These arise as a consequence of changes in the substitution pattern on the periphery of the molecule, at a substantial distance from the binding pocket. Herein, we explore these remote substituent effects and explain the observed behaviour through discussion of the way in which remote substituents can influence and control the global structure of a molecule through their demands upon conformational space. Peripheral modifications to a binuclear lanthanide motif derived from α,α′‐bis(DO3 Ayl)‐m‐xylene are shown to result in dramatic changes to the binding constant for isophthalate. In this system, the parent compound displays considerable conformational flexibility, yet can be assumed to bind to isophthalate through a well‐defined conformer. Addition of steric bulk remote from the binding site restricts conformational mobility, giving rise to an increase in binding constant on entropic grounds as long as the ideal binding conformation is not excluded from the available range of conformers. 相似文献
153.
Enthalpies of dilution of N-acetyl-l-prolinamide and equimolal solutions of this with N-acetylglycinamide, N-acetyl-l-alaninamide, N-acetyl-l-valinamide and N-acetyl-l-leucinamide have been determined at 298.15 K using a microcalorimetric procedure. The results obtained were used to calculate the pairwise enthalpic virial coefficients for both like—like (homotactic) and like—unlike (heterotactic) solute interactions. It is shown that the data can be predicted rather well using a group additivity approach with parameters obtained from earlier studies on α-amino and α-imino acid derivatives. 相似文献
154.
MM Boyle JJ Gassensmith AC Whalley RS Forgan RA Smaldone KJ Hartlieb AK Blackburn JP Sauvage JF Stoddart 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(33):10312-10323
A trans isomer of a figure-of-eight (Fo8) compound was prepared from an electron-withdrawing cyclobis(paraquat-p-phenylene) derivative carrying trans-disposed azide functions between its two phenylene rings. Copper(I)-catalyzed azide-alkyne cycloadditions with a bispropargyl derivative of a polyether chain, interrupted in its midriff by an electron-donating 1,5-dioxynaphthalene unit acting as the template to organize the reactants prior to the onset of two click reactions, afforded the Fo8 compound with C(i) symmetry. Exactly the same chemistry is performed on the cis-bisazide of the tetracationic cyclophane to give a Fo8 compound with C(2) symmetry. Both of these Fo8 compounds exist as major and very minor conformational isomers in solution. The major conformation in the trans series, which has been characterized by X-ray crystallography, adopts a geometry which maximizes its C?H???O interactions, while maintaining its π???π stacking and C?H???π interactions. Ab initio calculations at the M06L level support the conformational assignments to the major and minor isomers in the trans series. Dynamic (1) H?NMR spectroscopy, supported by 2D (1) H?NMR experiments, indicates that the major and minor isomers in both the cis and trans series equilibrate in solution on the (1) H?NMR timescale rapidly above and slowly below room temperature. 相似文献
155.
OA Blackburn M Tropiano TJ Sørensen J Thom A Beeby LM Bushby D Parker LS Natrajan S Faulkner 《Physical chemistry chemical physics : PCCP》2012,14(38):13378-13384
Thulium salts and complexes are shown to be emissive from three states in the excited state manifold of Tm(3+). Formation of the (1)D(2) state can result in luminescence, or in energy transfer to the lower energy (1)G(4) and (3)H(4) emissive states. Where chromophores are present in the ligand structure, emission is restricted to thulium centred emissive states that are lower in energy than the chromophore centred donor state. We have also observed direct multi-photon excitation of the thulium excited state manifold. Furthermore, additional transitions are observed in the multi-photon excitation spectra that are consistent with upconversion as a consequence of sequential single photon absorption and relaxation processes within the thulium excited state manifold. 相似文献
156.
157.
158.
Norman Blackburn 《Archiv der Mathematik》1980,35(1):75-78
Ohne ZusammenfassungHerrnWolfgang Gaschütz zum 60. Geburtstag am 11. 6. 1980 gewidmet 相似文献
159.
Miguel Octavio Sonia Frota-Pessoa Ivette F. Oppenheim James A. Blackburn 《Physics letters. A》1981,82(7):365-368
We provide theoretical justification within the framework of the generalized TDGL equations for the observation of a delay time when a current pulse is applied to a superconducting microbridge. Predictions are made as to the dependences of the delay time on current, microbridge length and relaxation times. 相似文献
160.