Silica-bound supramolecular chromatographic stationary phases and their applications

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Mekapothula, SR, 2022. Silica-bound supramolecular chromatographic stationary phases and their applications. PhD, Nottingham Trent University.

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Abstract

A novel co-pillar[4+1]arene incorporating bromo-octyl substituents has been synthesized for the first time using microwave irradiation in high yield (88%) in under four minutes. The yield of the new synthetic green methodology was validated while the traditional condensation method was repeated, which resulted in 26%. Subsequently, the co-pillar[4+1]arene was covalently bound to the surface of chromatographic silica particles. The resulting new stationary phase has been successfully validated to separate xylene isomers and their impurities, such as toluene and ethylbenzene, via flash column liquid chromatographic technique. Subsequently, the in-silico binding energy calculations via the Density Functional Tight Binding (DFTB) method implemented in DFTB+ version 1.3, were perfectly correlated with the observed experimental separation results.

The effective separation of a mixed peptide sample has been achieved via a computational strategy towards the bespoke design of a new silica bound supramolecular host capable of selectively interacting with different peptides via their morphology and amino acid functionalities. The experimental and in silico chromatographic behaviour of a sample of mixed peptides on a new co-pillar[4+1]arene bound silica HPLC stationary phase column was compared with RP-C18 and unfunctionalized silica (normal phase) column via liquid chromatography coupled with mass spectrometry (LC-MS/MS) and demonstrates superior separation selectivity and sensitivity for the mixed peptide solution being investigated.

A silica-bound C-butylpyrogallol[4]arene chromatographic stationary phase was prepared and characterised by thermogravimetric analysis, scanning electron microscopy, NMR and mass spectrometry. The chromatographic performance was investigated by using C60 and C70 fullerenes in reverse phase mode via flash column and high-pressure liquid chromatography (HPLC). The new stationary phase was observed to demonstrate size selective molecular recognition as postulated from our in-silico studies. The silica-bound C-butylpyrogallol[4]arene flash and HPLC stationary phases were able to separate a C60- and C70-fullerene mixture more effectively than an RP-C18 stationary phase. The presence of toluene in the mobile phase plays a significant role in achieving symmetrical peaks in flash column chromatography.

Item Type:	Thesis
Creators:	Mekapothula, S.R.
Date:	November 2022
Rights:	This work is the intellectual copyright of the author. You may copy up to 5% of this work for private study or personal, non-commercial research. Any re-use of the information contained within this document should be fully referenced, quoting the author, title, university, degree level, and pagination. Queries or requests for any other use, or if a more substantial copy is required, should be directed in the first instance to the owner of the Intellectual Property Rights.
Divisions:	Schools > School of Science and Technology
Record created by:	Linda Sullivan
Date Added:	21 Jun 2023 13:10
Last Modified:	21 Jun 2023 13:10
URI:	https://irep.ntu.ac.uk/id/eprint/49242