title: An unforeseen polymorph of coronene by the application of magnetic fields during crystal growth.
abstract: The continued development of novel drugs, proteins, and advanced materials strongly rely on our ability to self-assemble molecules in solids with the most suitable structure (polymorph) in order to exhibit desired functionalities. The search for new polymorphs remains a scientific challenge, that is at the core of crystal engineering and there has been a lack of effective solutions to this problem. Here we show that by crystallizing the polyaromatic hydrocarbon coronene in the presence of a magnetic field, a polymorph is formed in a β-herringbone structure instead of the ubiquitous γ-herringbone structure, with a decrease of 35° in the herringbone nearest neighbour angle. The β-herringbone polymorph is stable, preserves its structure under ambient conditions and as a result of the altered molecular packing of the crystals, exhibits significant changes to the optical and mechanical properties of the crystal.
authors.affiliation: Complex Functional Materials Group, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK.
authors.forename: Jason
authors.initials: J
authors.lastname: Potticary
authors.affiliation: Complex Functional Materials Group, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK.
authors.forename: Lui R
authors.initials: LR
authors.lastname: Terry
authors.affiliation: School of Physics, HH Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL, UK.
authors.forename: Christopher
authors.initials: C
authors.lastname: Bell
authors.affiliation: High Field Magnet Laboratory (HFML-EMFL), Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands.
authors.forename: Alexandros N
authors.initials: AN
authors.lastname: Papanikolopoulos
authors.affiliation: High Field Magnet Laboratory (HFML-EMFL), Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands.
authors.forename: Peter C M
authors.initials: PC
authors.lastname: Christianen
authors.affiliation: High Field Magnet Laboratory (HFML-EMFL), Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands.
authors.forename: Hans
authors.initials: H
authors.lastname: Engelkamp
authors.affiliation: Bristol Centre for Functional Nanomaterials, HH Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL, UK.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Collins
authors.affiliation: Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY, UK.|Dipartimento di Ingegneria Enzo Ferrari, Universita' di Modena e Reggio Emilia, Via Vivarelli 10, 41125 Modena, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Fontanesi
authors.affiliation: Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Kociok-Köhn
authors.affiliation: Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Crampin
authors.affiliation: Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY, UK.
authors.forename: Enrico
authors.initials: E
authors.lastname: Da Como
authors.affiliation: Complex Functional Materials Group, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK.
authors.forename: Simon R
authors.initials: SR
authors.lastname: Hall