KGRI Lecture Series: (Jan.21, 2020)"Using polymorphism to tune properties in organic crystals"


Keio University Global Research Institute (KGRI) aims to promote international research and educational exchange and invites those working in the forefront of research and education in Japan and overseas to give lectures.

On this occasion, Dr. Jason Potticary from University of Bristol in United Kingdom will give a lecture titled "Using polymorphism to tune properties in organic crystals".

Date & time: Tusesday, January 21, 14:45~16:15 (Open 14:35)
Venue: 14-202, Yagami Campus, Keio University
Keio University Global Research Institute (KGRI)
Language: English.
A summary will be provided in Japanese, after the lecture.
Open to anyone. No admission fee, Pre-registration not required.

Summary of Lecture:
The bulk physical properties of all crystalline, functional materials are ultimately a product of how each constituent part interacts with its nearest neighbours. In organic crystals this is typified by the interactions between molecules, generally speaking, functional groups or areas consisting of extremes of electrostatic potential. If one seeks to fine-tune any of these properties, control over how the molecules pack is essential and due to the immense potential benefits, gaining greater control over crystal growth is associated with improved properties1.
When designing a material, target properties are of course, specific to the application; in pharma, high water solubility is valued for increased gastrointestinal uptake, with agro-chem the opposite is true in order to prevent active ingredients emptying into the water-table after a single shower of rain, in organic semi-conductors, resistivity must be low2 and in high-energy materials, density must be high3. As the crystal packing is fundamental to all of these properties, fine control over crystal polymorphism is critical when designing functional materials.
The search for new polymorphs remains a scientific challenge that is at the core of crystal engineering. One of the most successful approaches in this field is to perform small chemical modifications to a specific molecular skeleton in order to direct different intermolecular interactions. Unfortunately, this strategy necessarily modifies the molecular building blocks, influencing their chemical nature, which is often undesirable.
In contrast, physical approaches rely on the use of pressure, bespoke solvents systems, external fields, etc. during crystal growth, which leaves the chemical structure of molecules unaltered. While it is known that magnetic forces can have an effect on solidification4, their use in controlling the crystalline structure of molecular materials is far less explored.
We describe how, by crystallizing the polyaromatic hydrocarbon coronene in the presence of a magnetic field5, it can be made to form as a previously unknown polymorph, how the properties are altered and how this can be extended to other molecular organic systems.

[1] Radacsi, N. et al., Cryst. Growth Des. 12, 3514-3520 (2012)
[2] Raza, K. et al., J. Drug Deliv. Sci. Technol. 39, 69-74 (2017)
[3] Sandhu, B. et al., Chem. Commun. 54, 4657-4660 (2018)
[4] Beaugnon, E. et al., J. Phys. I France 3, 399-421 (1993)
[5] Potticary, J. et al., Nat. Commun. 7, 11555 (2016)

2017-Current, Research associate, School of Chemistry, University of Bristol
2012-2017, Doctor of Philosophy (PhD) Course, Nano science / functional materials, University of Bristol


E-mail: kamihara_yoichi[at]keio.jp
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