Thesis-2011-Kulmaczewski.pdf (15.62 MB)
Mechanisms of formation of pseudocalixarene Schiff base macrocycles investigated by ESI-MS
thesis
posted on 2011-11-24, 12:23 authored by Rafal KulmaczewskiStarting from 4-substituted phenols, three dialdehydes were synthesised as Schiff base
pseudocalixarene macrocyclic precursors. Two of the dialdehydes, 2,2’–methylene-bis-
[(6-hydroxymethyl)-4-methylphenol] and 2,2’–methylene-bis-[(6-hydroxymethyl)-4-
phenylphenol] were structurally characterised. For the phenyl substituted compound
condensation with 1,3-diaminopropan-2-ol, with transition metal ions as template, was
investigated and a series of dinuclear complexes was synthesised and characterised by
IR, FAB-MS and elemental analysis. The analytical data implied that the complexes
have the same saddle shape conformation controlled by hydrogen bonds resulting from
mono-deprotonation of the methylendiphenol units as was observed in previous work.
A range of TM2M trinuclear complexes [TM = Cu(II), Ni(II) and M = Li(I), Na(I),
Mg(II), Ca(II)] of (2+2) macrocycles was synthesised and characterised by IR, MS
(FAB, ESI) and elemental analysis. Additionally [Cu2Ca(2+2)(NO3)2](MeOH)2 was
characterised by X-ray crystallography.
An ESI-MS was used to follow condensation reactions between 2,2’–methylene-bis-[(6-
hydroxymethyl)-4-tert-butylphenol] and 1,3-diaminopropan-2-ol in solution with
various templates. It was found that, when a transition metal is used alone, the reaction
produces only the (2+2) macrocycle. Cu(II) produced equilibrium mixtures containing
dicopper(II) and tricopper(II) species but Ni(II) and Zn(II) yielded only dinuclear
complexes.
When transition metal ions were used in combination with group 1 or group 2 metal
ions, the size of the macrocycle and nuclearity of the complex depended on the
synthetic route and nature of alkali or alkaline earth metal. Among the products
identified in the ESI-MS spectra were trinuclear complexes of the (2+2) macrocycle,
pentanuclear sandwich complexes of two (2+2) macrocycles, tetranuclear (3+3)
complexes, pentanuclear (4+4) and hexanuclear (6+6) species.
One of the routes resulted in formation of [BaCu4(4+4)]2+ ion via a
[BaCu4(dialdehyde)4]2+ cluster which was established to be a double template process
where both metals are necessary for formation of the macrocycle. The central Ba(II) ion
holds the dialdehydes together and the Cu(II) ion orients the carbonyl groups for Schiff
base condensation.
History
School
- Science
Department
- Chemistry
Publisher
© Rafal KulmaczewskiPublication date
2011Notes
A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.EThOS Persistent ID
uk.bl.ethos.634766Language
- en