Nanomaterials (NMs), with their diverse geometries and structures, multiple layers and components, and dynamic surfaces cannot be represented as a chemical graph and pose a conceptual challenge to development of a machine-readable structural representation.<sup>1</sup> Their 3D structures, the close correlation between size and properties, and their very high surface to volume ratios relative to the bulk, mean that NM representations require information on their chemical composition, physical, and structural features. Additional complications include the dynamic nature of their properties, that are influenced by the surrounding environmental chemistry (salts, biomolecules), temperature and time. Thus, a text representation for NMs must include information on its size, shape, internal structure, and surface characteristics that may include molecules chemically attached or physically adsorbed to the surface. We present here an update on the wide-ranging discussions on how best to accomplish the extension of the IUPAC International Chemical Identifier to represent nanomaterials, and progress towards developing the technical specification and the software to generate Nanomaterials InChIs.<br/><br/>The layers needed to capture NM structures include, but are not limited to, core composition (possibly multi-layered); surface topography, surface coatings or functionalization, doping with other chemicals; and representation of impurities. NM distributions (size, shape, composition, surface properties, etc.), types of chemical linkages connecting surface functionalization and coating molecules to the core, and various crystallographic forms exhibited by NMs also need to be encoded. An initial proposal was presented in [1] and significant further developments are underway, including a more versatile representation of crystal structures, representation of complex surface chemistries, alignment with the Codata Universal Description System for nanomaterials [2], demonstrated using nanomaterials families (e.g., graphene family materials, mixed and multi-component oxides such as those used in batteries including non-integer atom counts etc.). Determination of what belongs in the Nanomaterials InChI itself, versus what should be in the Auxiliary information is also under discussion, and the latest developments will be presented here.

Extending the InChI to nanomaterials: current progress and challenges

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.