Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

The Cationminus signpi Interaction.

Cations bind to the π face of an aromatic structure through a surprisingly strong, noncovalent force termed the cation-π interaction. The magnitude and generality of the effect have been established by gas-phase measurements and by studies of model receptors in aqueous media. To first order, the interaction can be considered an electrostatic attraction between a positive charge and the quadrupole moment of the aromatic. A great deal of direct and circumstantial evidence indicates that cation-π interactions are important in a variety of proteins that bind cationic ligands or substrates. In this context, the amino acids phenylalanine (Phe), tyrosine (Tyr), and tryptophan (Trp) can be viewed as polar, yet hydrophobic, residues.

https://science.sciencemag.org/content/sci/271/5246/163.full.pdf

Cation-π Interactions in Chemistry and Biology: A New View of Benzene, Phe, Tyr, and Trp

Stereoselective organic reactions in water.

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.

CH/π hydrogen bonds in crystals

6. Binding Properties of Cryptophanes 105 6.1. Complexation of Small Neutral Molecules 106 6.2. Complexation of Ammonium Guests 107 6.3. Complexation of Metal Cations 109 6.4. Complexation of Anion Guests 109 7. Dynamics of the Guest in the Cryptophane Cavity 109 7.1. Investigations by NMR Spectroscopy 109 7.2. Computational Investigations 111 7.3. Host-Guest Complexes in the Solid: Raman Microspectrometry 111

Cryptophanes and Their Complexes—Present and Future

The interaction of xenon with cryptophane-A in 1,1,2,2-tetrachloroethane-d2 is investigated by 129Xe and 1H NMR spectroscopy. Xenon is reversibly trapped into the cavity of this host to form a 1 to 1 host−guest complex with an apparent association constant K of the order of at least 3 × 103 M-1 at 278 K. The exchange between the free and bound xenon is slow on the 129Xe NMR time scale, and the bound xenon resonance is shifted by approximately 160 ppm to lower frequencies with respect to the free xenon resonance. The xenon complex is at least 4 and 20 times more stable, respectively, than the corresponding chloroform and methane complexes under the same conditions. The stability of this xenon complex appears to be much greater than that of the previously described xenon complex of α-cyclodextrin in water. This is probably due to the combination of three favorable effects:  (i) good size matching between the guest and the cryptophane cavity in its most relaxed conformation, resulting in the optimization of ...

129Xe and 1H NMR Study of the Reversible Trapping of Xenon by Cryptophane-A in Organic Solution

Complexation of Methane and Chlorofluorocarbons by Cryptophane‐A in Organic Solution

Three azaphosphatranes were used as organocatalysts for the synthesis of cyclic carbonates from CO2 and epoxides. They proved to be efficient single-component, metal-free catalysts for the reaction of simple or activated epoxides (styrene oxide, epichlorohydrin, glycidyl methyl ether) with CO2 under mild reaction conditions, displaying high stability and productivity over several days of reaction. Substitution patterns on the catalyst were shown to affect activity and stability. Kinetic analysis allowed investigation of the reaction mechanism.

Azaphosphatranes as Structurally Tunable Organocatalysts for Carbonate Synthesis from CO2 and Epoxides

In the wide area of host–guest chemistry, hemicryptophanes, combining a cyclotribenzylene (or cyclotriveratrylene CTV) unit with another different C3-symmetrical moiety, appears as a recent family of molecular cages. The synthesis and recognition properties of the first hemicryptophane were reported in 1982 by Collet and Lehn, but the very little attention received by this class of host compounds in the 20 years following this first promising result can account for their apparent novelty. Indeed, in the last 10 years hemicryptophanes have aroused growing interest, and new aspects have been developed. Thanks to the rigid shaping unit of the north part (CTV) and also the variable and easily functionalized south moiety, hemicryptophanes are revealed to be inherently chiral ditopic host compounds, able to encapsulate various guests, including charged and neutral species. They also enter the field of stimuli-responsive supramolecular systems exhibiting controlled functions. Moreover, endohedral functionalizati...

/pdf/emergence-of-hemicryptophanes-from-synthesis-to-applications-1uhvs3bx8y.pdf

Jean-Pierre Dutasta

Papers

Cryptophanes and Their Complexes—Present and Future

129Xe and 1H NMR Study of the Reversible Trapping of Xenon by Cryptophane-A in Organic Solution

Complexation of Methane and Chlorofluorocarbons by Cryptophane‐A in Organic Solution

Azaphosphatranes as Structurally Tunable Organocatalysts for Carbonate Synthesis from CO2 and Epoxides

Emergence of Hemicryptophanes: From Synthesis to Applications for Recognition, Molecular Machines, and Supramolecular Catalysis