Gradient-Driven Molecule Construction: An Inverse Approach Applied to the Design of Small- Molecule Fixating Catalysts

Rational design of molecules and materials usually requires extensive screening of molecular structures for the desired property. The inverse approach to deduce a structure for a predefined property would be highly desirable, but is, unfortunately, not well defined. However, feasible strategies for such an inverse design process may be successfully developed for specific purposes. We discuss options for calculating jacket potentials that fulfill a predefined target requirementa concept that we recently introduced (Weymuth and Reiher, MRS Proceedings 2013, 1524, DOI:10.1557/opl.2012.1764). We consider the case of small-molecule activating transition metal catalysts. As a target requirement we choose the vanishing geometry gradients on all atoms of a subsystem consisting of a metal center binding the small molecule to be activated. The jacket potential can be represented within a full quantum model or by a sequence of approximations of which a field of electrostatic point charges is the simplest. In a second step, the jacket potential needs to be replaced by a chemically viable chelate-ligand structure for which the geometry gradients on all of its atoms are also required to vanish. To analyze the feasibility of this approach, we dissect a known dinitrogen-fixating catalyst to study possible design strategies that must eventually produce the known catalyst. (c) 2014 Wiley Periodicals, Inc.