Rationalizing the influence of small-molecule dopants on guanine crystal morphology

Wagner, Avital, Hill, Adam, Lemcoff, Tali, Livne, Eynav, Avtalion, Noam, Casati, Nicola, Kariuki, Benson M. ORCID: https://orcid.org/0000-0002-8658-3897, Graber, Ellen R., Harris, Kenneth D. M. ORCID: https://orcid.org/0000-0001-7855-8598, Cruz-Cabeza, Aurora J. and Palmer, Benjamin A. 2024. Rationalizing the influence of small-molecule dopants on guanine crystal morphology. Chemistry of Materials 36 (18) , 8910–8919. 10.1021/acs.chemmater.4c01771

Preview

PDF - Published Version Available under License Creative Commons Attribution. Download (4MB) | Preview

Abstract

Many spectacular optical phenomena in animals are produced by reflective assemblies of guanine crystals. The crystals comprise planar H-bonded layers of π-stacked molecules with a high in-plane refractive index. By preferentially expressing the highly reflective π-stacked (100) crystal face and controlling its cross-sectional shape, organisms generate a diverse array of photonic superstructures. How is this precise control over crystal morphology achieved? Recently, it was found that biogenic guanine crystals are composites, containing high quantities of hypoxanthine and xanthine in a molecular alloy. Here, we crystallized guanine in the presence of these dopants and used computations to rationalize their influence on the crystal morphology and energy. Exceptional quantities of hypoxanthine are incorporated into kinetically favored solid solutions, indicating that fast crystallization kinetics underlies the heterogeneous compositions of biogenic guanine crystals. We find that weakening of H-bonding interactions by additive incorporation elongates guanine crystals along the stacking direction─the opposite morphology of biogenic crystals. However, by modulation of the strength of competing in-plane H-bonding interactions, additive incorporation strongly influences the cross-sectional shape of the crystals. Our results suggest that small-molecule H-bond disrupting additives may be simultaneously employed with π-stack blocking additives to generate reflective platelet crystal morphologies exhibited by organisms.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Chemistry
Publisher:	American Chemical Society
ISSN:	0897-4756
Date of First Compliant Deposit:	2 October 2024
Date of Acceptance:	14 August 2024
Last Modified:	07 Oct 2024 11:00
URI:	https://orca.cardiff.ac.uk/id/eprint/172541

Actions (repository staff only)

Edit Item