Automated flow synthesis of algorithmically designed ferroelectric nematogens

• Published in: Liquid crystals Vol. 50; no. 3; pp. 534 - 542
• Main Author: Mandle, Richard J.
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 19.02.2023; Taylor & Francis Ltd
• Subjects: Automation; Continuous flow; Ferroelectric materials; ferroelectric nematics; Ferroelectricity; Fingerprinting; flow chemistry; Genetic algorithms; Libraries; Liquid crystals; Molecular structure; Neural networks; RM734; Synthesis
• ISSN: 0267-8292; 1366-5855
• DOI: 10.1080/02678292.2023.2208550

The synthesis of the ferroelectric nematic material RM734 is telescoped into a single continuous flow process, utilising inline liquid-liquid separation to remove reactants and by-products from the reaction stream. Following the final synthetic step, we subject the semi-crude material to offline automated chromatography. Materials can be prepared on a gram scale (12 minutes) and chromatographically purified (8 minutes) in around 20 minutes. Over a given time interval the system described herein can prepare a far larger number of materials (on gram scale) than an experienced chemist. Secondly, we implement an established process for generation of new molecular structures via a genetic algorithm, which generates many new candidate structures per iteration. A filter removes undesirable structures, and a fast semi-empirical QM calculation is performed on those that remain. A neural network trained against a library of nematic and ferroelectric nematic materials is used to rank the candidate structures based on the QM output and a fingerprinting process, with the highest scoring candidates then used to seed a new round of mutations. We combine these two approaches; we generated and ranked several tens of thousands of variants of RM734 and synthesised a small library of materials using our continuous flow protocol.