Boron-nitride doped polycyclic aromatic hydrocarbon co-crystals for 2-D molecular recognition

Warren, Jack 2024. Boron-nitride doped polycyclic aromatic hydrocarbon co-crystals for 2-D molecular recognition. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

In the modern world where chemical impacts to human and environmental wellbeing is a primary concern, it is important to develop discreet, resistant chemical sensors for the detection of harmful molecules produced by human activities. Whether its from chemical warfare agents, toxic pesticides or small toxic molecules produced as a by-product, all can have a dramatic impact on the health of living beings. A single molecule chemical sensor that can detect and identify such molecules will increase the ability of organisations to respond to crises where, currently the damage to the environment is already done by the time such toxic molecules are identified. This thesis investigates boron-nitride doped polycyclic aromatic hydrocarbons (PAHs) as a potential single molecule chemical sensor. Using density functional theory (DFT) methods, cocrystals of 2-8-14-trixylyl-hexaphenyl-borazinocoronene (HBBNC) and 2,8,14-trixylylhexabenzocoronene (HBC) containing a range of functionalised phenyl solvates are studied. This is order to evaluate the effect of boron-nitride doping for the use of nanographene’s as single molecule chemical sensors and to determine the type of interactions dominating the HBBNC and HBC crystals. The HBBNC and HBC co-crystals with phenyl solvates are introduced initially and it was observed that some of the HBBNC/solvate co-crystals contain multiple orientations for the solvate molecule. Using available experimental data, the appropriate choice of computational settings for modelling BN doped PAHs was tested. The PBE exchange correlation functional with the nonlocal many-body dispersion correction was the best for balancing computational efficiency with accuracy. The interactions between HBBNC, HBC and the isolated solvates were evaluated, and the BN doped region of HBBNC shows marginally increased interaction strength with the solvates ii over HBC. It was found that the enhancement of adsorption potential is inversely proportion to the size and electronegativity of the solvate. In addition, the potential energy landscape (PES) of HBBNC and HBC were evaluated as a function of the rotation and translations of isolated phenyl derivatives. The study then moves to focus on the co-crystals where the internal rotational PES as a function of phenyl derivative is evaluated to determine what interactions stabilise the solvate orientations. The thermal expansion coefficient was calculated to be positive for all systems predicting the amount the PAH co-crystal expand with increasing temperature. Then finally a Boltzmann weighted statistical analysis of the orientations of the internal solvate was performed to predict the temperatures different orientations occur. Overall, this thesis provides new knowledge the behaviour of BN doped PAH co-crystals, evaluating the impact of the inclusion of BN on the adsorption potential of HBBNC for applications as a single molecule chemical sensor.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Chemistry
Date of First Compliant Deposit:	2 August 2024
Last Modified:	02 Aug 2024 10:46
URI:	https://orca.cardiff.ac.uk/id/eprint/171123

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