To further highlight the link between approximate symmetry and homomolecular structures that crystallize with large numbers of molecules in the asymmetric unit (Z′ ≥ 12), the most recent structures of this type have been analyzed, and the approximate symmetry identified. In most cases, when approximate symmetry is considered, a smaller approximate unit cell can be described, where the effective Z′ is lower than that of the original unit cell. For one example, defining an approximate cell was not appropriate, and the approximate symmetry in the structure was hence described using approximate layer and rod groups. Generally, it appears that though the molecules in the asymmetric units of these structures may not be related by crystallographic symmetry, symmetrical relationships appear to be retained as much as possible in cases where the packing is awkward and precise symmetry is not possible. Revealing the link between extreme-Z′ structures and theoretical structures with lower Z′ is of potential use to the field of crystal structure prediction with regard to the prediction of structures where Z′ > 1.

Inhibitors of epidermal growth factor receptor (EGFR) kinase activity are clinically effective treatments for lung cancers driven by activating mutations in EGFR. Resistance to inhibitors develops ove...

Ultralight photovoltaics are indispensable wherever every gram counts, from self-powered Internet of Things nodes to free-hanging greenhouse covers. In dye-sensitized solar cells (DSCs) the required 4...

A mechanochemical protocol for the direct synthesis of organosodium compounds is developed using cheap and shelf-stable sodium lumps and readily available organic halides under bulk, solvent-free cond...

Common methods for assigning atom-centered partial charges in computational chemistry, such as RESP and AM1-BCC, rely on quantum mechanical or semiempirical calculations of the molecule of interest, which are expensive to compute and dependent on the choice of input molecular conformer(s). Graph neural network (GNN) based continuous atom embeddings have been shown to be a fast and flexible solution for partial charge assignment, but those developed so far for condensed phase modeling have usually been trained to reproduce AM1-BCC charges, which themselves seek to reproduce the HF/6-31G(d) molecular electrostatic potential. Here, we investigate the suitability of various common charge assignment schemes, including ESP and atoms-in-molecule (AIM) based approaches, as training targets for new GNN-based charge models. We show that the strengths of both approaches can be combined by cotraining GNN models to AIM charges and molecular dipoles and electrostatic potentials. We collect a data set of quantum mechanical AIM properties computed at a high level of theory (ωB97X-D/def2-tzvpp), in both vacuum and implicit solvent, and train new GNN charge models to each. Charges can be scaled between the vacuum and solvated charge sets, and combined with Lennard-Jones parameters optimized using the Open Force Field infrastructure, to yield force fields that are suitably polarized for condensed phase modeling. We further demonstrate that the charge models may be applied to explore electrostatics-driven structure–activity relationships in medicinal chemistry. The charge models are freely available at: https://github.com/cole-group/nagl-mbis/.

Research Assistant/Associate in National Crystallography Service

New research demonstrates a simple, eco-friendly method to break down Teflon® – one of the world’s most durable plastics – into useful chemical building blocks.

Peptide analogues featuring both central and N–N axial chirality were efficiently synthesised using a 4-component Ugi reaction. This method demonstrates a broad substrate scope, affording the target c...

Beilstein Journal of Organic Chemistry

The University is playing a key role in an AI Growth Zone in the North East which is set to unlock more than 5,000 new jobs and bring in £30 billion in investment as the region becomes a hub for AI.