Supramolecular behaviour of some heterocyclic cored pincers
Supramolecular behaviour of some heterocyclic cored pincers
The solid-state behaviour of pincer shaped molecules with a heterocycle at the hinge and amide- or ester-linked aromatic arms are investigated. A number of core units have been investigated including pyridine-2,6-dicarboxylic acid, benzene-1,3-dicorboxylic acid, thiophene-2,5-dicarboxylic acid, pyridine-2,6-dicarboxylic acid N-oxide, furan-2,5-dicarboxylic acid and pyrrole-2,5-dicarboxylic acid. Furan-2,5- and pyrrole-2,5-dicarboamides have proved more difficult to synthesise.
The conformational behaviours of various core units were calculated using computational modelling and are compared with X-ray crystallographic results. The solid-state structures of amide-linked pincers are governed primarily by the formation of strong hydrogen bonds between both of the amide protons and one amide carbonyl, though in a few cases a different proton-acceptor (Npyridine or ArOMe) binds to the amide protons. The two environments of the carbonyl groups (bound and unbound) are clearly visible in the solid-state IR spectra.
Abstraction of the amide hydrogens with a base forms a dianionic ligand and bis (methyl-(2-pyridyl)) pyridine-2,6-dicarboxamide forms complexes with nickel (II) and copper (II).
The solid-state structures of the ester-linked pincers often contain supramolecular tapes that are held together by two weak C-H...O bonds between neighbouring hinge units (H...O distance 2.4-2,8Å). Pyridine-cored ester-linked pincers seem to have an additional, central C-H...N bond (H...N distance 2.4-2.7 Å), but this may be simply an artefact of the system's geometry. Solid-state IR identifies one carbonyl environment for esters that form symmetrical supramolecular tapes and two for esters that deviate from ideal tape formation.
University of Southampton
Gomm, John Reginald
b0431df6-4ec1-45ac-8a72-e11b0c25ebc0
2002
Gomm, John Reginald
b0431df6-4ec1-45ac-8a72-e11b0c25ebc0
Gomm, John Reginald
(2002)
Supramolecular behaviour of some heterocyclic cored pincers.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The solid-state behaviour of pincer shaped molecules with a heterocycle at the hinge and amide- or ester-linked aromatic arms are investigated. A number of core units have been investigated including pyridine-2,6-dicarboxylic acid, benzene-1,3-dicorboxylic acid, thiophene-2,5-dicarboxylic acid, pyridine-2,6-dicarboxylic acid N-oxide, furan-2,5-dicarboxylic acid and pyrrole-2,5-dicarboxylic acid. Furan-2,5- and pyrrole-2,5-dicarboamides have proved more difficult to synthesise.
The conformational behaviours of various core units were calculated using computational modelling and are compared with X-ray crystallographic results. The solid-state structures of amide-linked pincers are governed primarily by the formation of strong hydrogen bonds between both of the amide protons and one amide carbonyl, though in a few cases a different proton-acceptor (Npyridine or ArOMe) binds to the amide protons. The two environments of the carbonyl groups (bound and unbound) are clearly visible in the solid-state IR spectra.
Abstraction of the amide hydrogens with a base forms a dianionic ligand and bis (methyl-(2-pyridyl)) pyridine-2,6-dicarboxamide forms complexes with nickel (II) and copper (II).
The solid-state structures of the ester-linked pincers often contain supramolecular tapes that are held together by two weak C-H...O bonds between neighbouring hinge units (H...O distance 2.4-2,8Å). Pyridine-cored ester-linked pincers seem to have an additional, central C-H...N bond (H...N distance 2.4-2.7 Å), but this may be simply an artefact of the system's geometry. Solid-state IR identifies one carbonyl environment for esters that form symmetrical supramolecular tapes and two for esters that deviate from ideal tape formation.
Text
874476.pdf
- Version of Record
More information
Published date: 2002
Identifiers
Local EPrints ID: 464761
URI: http://eprints.soton.ac.uk/id/eprint/464761
PURE UUID: 0fe47e29-7ddf-45e1-97cf-7ae63e9252de
Catalogue record
Date deposited: 05 Jul 2022 00:00
Last modified: 16 Mar 2024 19:44
Export record
Contributors
Author:
John Reginald Gomm
Download statistics
Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.
View more statistics