Search results for "pi interaction"

Iminium Catalysis (n → π*)

2016

Crystallographic and (spectro)electrochemical characterizations of cobalt(II) 10-phenyl-5,15-di-p-tolylporphyrin

2021

International audience; The synthesis, cyclic and rotating disk electrode voltammograms, UV-visible absorption and Xray diffraction analyses of cobalt(II) 10-phenyl-5,15-dip -tolylporphyrin (1-Co) are described. 1-Co was crystallized by slow diffusion of n-hexane into a concentrated CH2Cl2 solution. X-ray diffraction analyses reveals porphyrin aromatic cycle stacking in the crystal, C-H•••π interactions of the CH2Cl2 solvent with the π-system of one tolyl group and Co(II)•••π (porphyrin ring) interactions. The abstraction of 1.0 F/mol during the electrolysis at the first oxidation potential was followed by spectroelectrochemistry. It leads to the Co(II) → Co(III) transformation rather than …

CH-Directed Anion-π Interactions in the Crystals of Pentafluorobenzyl-Substituted Ammonium and Pyridinium Salts

2010

Simple pentafluorobenzyl-substituted ammonium and pyridinium salts with different anions can be easily obtained by treatment of the parent amine or pyridine with the respective pentafluorobenzyl halide. Hexafluorophosphate is introduced as the anion by salt metathesis. In the case of the ammonium salt 4, water co-crystallisation seems to suppress effective anion-pi interactions of bromide with the electron-deficient aromatic system, whereas with salts 5 and 6 such interactions are observed despite the presence of water. However, due to asymmetric hydrogen-bonding interactions with ammonium side chains, the anion of 5 is located close to the rim of the pentafluorophenyl group (eta(1) interac…

Experimental investigation of anion-π interactions : Applications and biochemical relevance

2015

Chemical communications 52(9), 1778 - 1795(2016). doi:10.1039/C5CC09072E

Phenylethynyl- and Phenylethenylmetacyclophanes with π,π Interactions

1999

Connecting Electron-Deficient and Electron-Rich Aromatics to Support Intermolecular Interactions in Crystals (Eur. J. Org. Chem. 15/2015)

2015

A Straightforward Electroactive π-Extended Tetrathiafulvalene (exTTF) Building Block

2012

The synthesis and X-ray structure of a new and readily available exTTF derivative (6) bearing a methyltriphenylphosphonium bromide moiety as a new building block for the construction of electroactive molecules is reported. The phosphonium salt 6, which was prepared in one step from 2-hydroxymethyl-exTTF as a stable yellow solid in 84 % yield, efficiently undergoes Wittig olefination reactions with a variety of aldehydes to predominantly form the E isomer. Electronic spectra and cyclic voltammetry of the novel compounds reveal the electronic communication between the electroactive units.

Perfluoro-1,1′-biphenyl and perfluoronaphthalene and their derivatives as π-acceptors for anions

2015

Addition of anions to perfluorinated 1,1′-biphenyl 1 or naphthalene 2 results in a shift of the 19F NMR signals. However, any specific interaction cannot be assigned to this effect. In order to study the interaction in more detail, the salt derivatives 3 and 4 were prepared and studied by single crystal X-ray diffraction revealing weak anion–π interactions in the solid state.

Connecting Electron-Deficient and Electron-Rich Aromatics to Support Intermolecular Interactions in Crystals

2015

Five compounds bearing electron-deficient pentafluorophenyl as well as electron-rich (salicylate or indole) aromatic moieties connected by amide or ester linkages were investigated by X-ray diffraction. In the crystals, various interactions (π–π, lone pair–π) between the different aromatic units are important structure controlling factors in addition to the stronger inter- or intramolecular hydrogen bonds induced by the amide and ester moieties. The hydrogen bonding leads to polymeric and macrocyclic assembly of the molecular building blocks.

Positional Isomers of Chromophore–Peptide Conjugates Self-Assemble into Different Morphologies

2018

Ordering π-systems into defined supramolecular structures is important for the development of organic functional materials. In recent years, peptides with defined secondary structures and/or self-assembly properties were introduced as powerful tools to order peptide-chromophore conjugates into different morphologies. This work explores whether or not the directionality of peptides can be used to control the self-assembly. The position of the π-system in conjugates between oligoprolines and perylene monoimide (PMI) chromophores was varied by attaching the PMI moiety to the second-to-last residue from the C- and N-termini, respectively. Microscopic and diffraction analysis revealed that the p…