Josette Canceill

Bio: Josette Canceill is an academic researcher from Collège de France. The author has contributed to research in topics: Cryptophane & Cyclotriveratrylene. The author has an hindex of 23, co-authored 51 publications receiving 1637 citations. Previous affiliations of Josette Canceill include Centre national de la recherche scientifique & École Normale Supérieure.

Analytical optical resolution of bromochlorofluoromethane by enantioselective inclusion into a tailor-made cryptophane and determination of its maximum rotation

Abstract: A l'aide de la spectrometrie RMN, on etudie le dedoublement optique du bromochlorofluoromethane qui est inclus dans une cavite de compose chiral le cryptophane C

Cyclotriveratrylenes and cryptophanes: Their synthesis and applications to host-guest chemistry and to the design of new materials

Abstract: A review is given of the recent developments of the chemistry of cyclotriveratrylenes and cryptophanes, and of their use in the study of host-guest interactions. Experiments dealing with the complexation of tetrahedral species including neutral molecules (halogenomethanes and alkanes) and organic soft cations (tri- and tetramethyl ammonium cations, acetylcholine) are discussed. Prospective applications of cyclotriveratrylenes and cryptophanes to the design of ferroelectric liquid crystals and of three-dimensional charge tranfer materials are presented.

Multichromophoric cyclodextrins. 4. Light conversion by antenna effect

Abstract: A water soluble β-cyclodextrin (CD-NA) bearing seven naphthoyl chromophores forms very stable 1:1 complexes with a merocyanine laser dye DCM-OH (4-(dicyanomethylene)-2-methyl-6-(p-(bis(hydroxyethyl)amino)styryl)-4H-pyran). The antenna effect, i.e. energy transfer from the naphthoyl antenna chromomophores to the encased dye, is shown to occur with 100% efficiency. The stability of the complexes is very high (Ks ≈ 105) owing to the contribution of the naphthoate residues. The structural features of the complexes have been examined in detail: circular dichroism experiments confirm the expected axial orientation of DCM-OH in the cavity of CD-NA, and fluorescence anisotropy measurements together with 13C-NMR longitudinal relaxation time measurements show that the complex formed between CD-NA and DCM-OH is tight. The mechanisms of homotransfer (i.e., between naphthoate chromophores) and heterotransfer (i.e., from naphthoate chromophores to DCM-OH included in the cavity) are discussed in light of existing theor...

Optical activity due to isotopic substitution. Synthesis, stereochemistry, and circular dichroism of (+)- and (-)-[2,7,12-2H3]cyclotribenzylene

Abstract: The enantiomers of the specified compound, whose chirality is due to isotopic substitution, were synthesized from cyclotriguaiacylene; and their absolute configuration was established as M-(-) or P-(+). The phenolic groups in the starting compound were removed by hydrogenolysis of the corresponding tris(2-phenyl-1-tetrazolyl) ether, and the resulting cyclotrianisylene was demethylated into cyclotriphenolene. Optical resolution of the latter compound followed by deuteriolysis of the phenolic groups then provided the desired (+) and (-)-cyclotribenzylene with a high isotopic purity. The energy barrier for the crown inversion in the titled compound was calculated from racemization rates. Interpretation in terms of vibronic rotation of the B/sub 2u/ transition moment, induced by the deuterium atoms perturbing the breathing mode of each phenyl ring, was qualitatively consistent with the observed spectrum.

CH/π hydrogen bonds in crystals

Abstract: The nature and characteristics of the CH/π interaction are discussed by comparison with other weak molecular forces such as the CH/O and OH/π interaction. The CH/π interaction is a kind of hydrogen bond operating between a soft acid CH and a soft base π-system (double and triple bonds, C6 and C5 aromatic rings, heteroaromatics, convex surfaces of fullerenes and nanotubes). The consequences of CH/π hydrogen bonds in supramolecular chemistry are reviewed on grounds of recent crystallographic findings and database analyses. The topics include intramolecular interactions, crystal packing (organic and organometallic compounds), host/guest complexes (cavity-type inclusion compounds of cyclodextrins and synthetic macrocyclic hosts such as calixarenes, catenanes, rotaxanes and pseudorotaxanes), lattice-inclusion type clathrates (including liquid crystals, porphyrin derivatives, cyclopentadienyl compounds and C60 fullerenes), enantioselective clathrate formation, catalytic enantioface discriminating reactions and solid-state photoreaction. The implications of the CH/π concept for crystal engineering and drug design are evident.

Biomimetic Reactions Catalyzed by Cyclodextrins and Their Derivatives.

Abstract: Cyclodextrins are extremely attractive components of artificial enzymes and other biomimetic materials. They are readily available, they bind hydrophobic substrates into their cavities in water solution, and they have two rims of hydroxyl groups (Figure 1) that can either react with substrates themselves or be used to attach other catalytic and functional groups. Of course, they have disadvantages. For one, unless they are extensively modified their complexes with substrates can be rather flexible and, perhaps, with unpredictable preferred geometry. They are also unstable to strong acid. Thus for some purposes such synthetic cavity species as calixerenes1 or synthetic macrocycles2-4 may have advantages. However, one of the chief advantages of cyclodextrins is highly attractivesthey are readily available, so it is possible to avoid the synthesis of a binding group and go directly to studies of what can be achieved with their use. Afterward, the lessons learned may be applied to other systems with advantage. This review will cover all the literature on reactions in which cyclodextrins bind substrates and then either catalyze their reactions or mimic a step in an enzymatic catalytic sequence. However, it will not describe work in which cyclodextrins simply change the course of a reaction without playing an obvious catalytic role involving substrate binding. For example, there are systems in which the main function of the cyclodextrin seems to be to complex a metal ion and keep it in solution.5-11 There are other studies in which binding into a cyclodextrin simply alters the selectivity of attack by an external reagent in some way12-24 or causes solubilization to facilitate phase transfer catalysis.12,25,26 Presumably such other areas are described elsewhere in this volume. While much work on artificial enzymes using cyclodextrins has been done in the author’s laboratory, and will be described, every effort is made to describe all the relevant work in the field. Several reviews of this subject already exist and should be consulted for further information.2,27-70 The readily Ronald Breslow, born in 1931 in Rahway, NJ, completed his B.A. in chemistry in1952, his M.A. in medical science in 1953, and his Ph.D. in chemistry in 1955 with R. B. Woodward, all at Harvard University. After a postdoctoral year with Alexander Todd in Cambridge, he came to Columbia University where he is now University Professor and Professor of Chemistry. His work on enzyme models, on novel conjugated aromatic and antiaromatic molecules, on electrochemical and hydrophobic methods in mechanistic chemistry, and on anticancer cytodifferentiating agents has been recognized by a number of awards, including the U.S. National Medal of Science. In 1996, he served as President of the American Chemical Society.

Long-Range Resonance Energy Transfer in Molecular Systems

Abstract: The current state of understanding of molecular resonance energy transfer (RET) and recent developments in the field are reviewed. The development of more general theoretical approaches has uncovered some new principles underlying RET processes. This review brings many of these important new concepts together into a generalization of Forster's original theory. The conclusions of studies investigating the various approximations in Forster theory are summarized. Areas of present and future activity are discussed. The review covers Forster theory for donor-acceptor pairs and electronic coupling for singlet-singlet, triplet-triplet, and superexchange-mediated energy transfer. This includes the transition density picture of Coulombic coupling as well as electronic coupling between molecular aggregates (excitons). Spectral overlaps and ensemble energy transfer rates in disordered aggregates, the role of dielectric properties of the medium, weak versus strong coupling, and new models for energy transfer in complex molecular assemblies are also described.