Structure and mechanism in macrocyclic systems

Labat, G.C., 2002. Structure and mechanism in macrocyclic systems. PhD, Nottingham Trent University.

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The aim of this work was to produce a range of crystalline thiophene-based macrocycles and macrocycles complexes and to investigate their structure-property relationships. This involved studies of the structures of macrocycles and also their mechanism of complexation with metals including nickel, copper, aluminium, and silver. The macrocycles and relevant complexes were prepared and crystallised from solution, and their structure-property relationships investigated by using X-ray crystallography and spectroscopy, in addition to theoretical calculations of molecular geometry and binding energy, and optimisation of molecular geometry using suites of molecular modelling programs.

The synthesis of macrocycles 15-ethyl-2,5,8-trioxa-12,18-dithia-15-aza-tricyclo-tricosa-l(18),9(13)-10-19-tetraene 10a; 18,24-bis-(methyl)-2,5,8,11.2i-pentaoxa-15,27- dithia-18,24-diaza-tricyclo-nonacosa-l(26),12(16),13,28-tetraene 22 and 15,35-dipropyl- 2,5,8,22,25,28-hexaoxa-12,18,32,38-tetrathia-15,35-diaza-pentacyclo-tetraconta-1(37),9(13),10,17(21),19,29(33),30,39-octaene 24, involved the synthesis of intermediate molecules such as thiophene open-chains. These intermediates are: diethyl-3,4dihydroxythiophene-2,5-dicarboxylate 15; thiophene bisester; thiophene bisacid; bis- (3-oxythienyl)ethane 16; a,co-bis-(3-ethyloxythienyl)ethane 20; 18-carboxylic-a,co-bis- (3-oxythienyl)ethane 16; thiophene bisaldehyde or -bis-(2-formyl-3- oxythienyl)ethane 19; bis-(2-propylimine3-oxythienyl)ethane and -bis-(2- propylamine3-oxythienyl)ethane. The structure of compounds 18,21-bis-(methyl)- 2,5,8,ll-tetraoxa-15,24-dithia-18,21-diaza-tricyclo-hexacosa-l(26),12(16),13,25-tetraene 8b; 10a; 18-ethyl-2,5,8,11-tetraoxa-15,21-dithia-azatricyclo-tricosa-1,22,12,13-tetraene 10b; 15; 16; 5,17-dimethyl-bis-(3-oxythienyl)ethane 17; 18; 19; 20; 2,5,8,11- tetraoxa-15,26-dithia-18,21-diaza-tricyclo-nonacosa-l(26), 12(16), 13,28-tetraene 23 and 24 were characterised by X-ray crystallography as well as the structure of macrocycle 24 complexed with Cu(ClO4)2 50 and with Cu(ClO4)2 54. The other thiophene-based macrocycles which were not characterised by x-ray crystallography as well as 10a were geometrically optimised by molecular modelling.

The results obtained showed that metal complexation did not always occur in macrocycle cavities of apparently optimum size and that in the case of silver the metal did not enter the macrocycle, but bonded externally to an electronegative atom from the ring. The infrared spectroscopy showed some peaks that were characteristic of the counterion (for example perchlorate and isocyanate), but it was also possible to identify some new peaks and some peak shifts due to complexation of the metal ions with the ligand (for example Al(III)-O). Moreover, the 1H and 13CNMR spectroscopy revealed several significant peak shifts between the free ligands and the complexed ligand due to interactions between the ligand and the metal ion, which depend on through which atoms and how strongly the metal ion is complexed with the ligand.

Item Type: Thesis
Creators: Labat, G.C.
Date: 2002
ISBN: 9781369325324
Divisions: Schools > School of Science and Technology
Record created by: Laura Ward
Date Added: 25 Jun 2021 15:16
Last Modified: 13 Dec 2023 14:10

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