DENOPTIM: Software for Computational de Novo Design of Organic and Inorganic Molecules

A general-purpose software package, termed DE Novo OPTimization of In/organic Molecules (DENOPTIM), for de novo design and virtual screening of functional molecules is described. Molecules of any element and kind, including metastable species and transition states, are handled as chemical objects that go beyond valence-rules representations. Synthetic accessibility of the generated molecules is ensured via detailed control of the kinds of bonds that are allowed to form in the automated molecular building process. DENOPTIM contains a combinatorial explorer for screening and a genetic algorithm for global optimization of user-defined properties. Estimates of these properties may be obtained to form the fitness function (figure of merit or scoring function) from external molecular modeling programs via shell scripts. Examples of a range of different fitness functions and DENOPTIM applications, including an easy-to-do test case, are described. DENOPTIM is available as Open Source from https://github.com/denoptim-project/DENOPTIM.acceptedVersio

Molecular modeling of zinc paddlewheel molecular complexes and the pores of a flexible metal organic framework

A new all-atom first-principles force field (FF) is constructed for the bimetallic, four-bladed zinc paddlewheel (ZPW) motif. Zinc-ligand interactions are described via Morse functions and the angular geometry at the metal centers is modeled with a pure ligand-ligand repulsion term. The ZPW-FF is principally based on 15 DFT-optimized model systems of general formula ZnPR.nL, where ZnP is the base Zn2(O2CR)4 unit, R = H, CH3 or CF3, L = NH3 or pyridine, and n = 0, 1 or 2. It correctly generates the distorted tetrahedral coordination of the uncapped [Zn2(O2CR)4] species in their ground states as well as giving reasonable structures and energies for the higher symmetry D4h transition state conformations. The zinc-ligand Morse function reference distance, r 0 , is further refined against 30 complexes located in the Cambridge Structural Database and this FF is applied to pore models of the flexible metal-organic framework (MOF) [Zn(bdc)2(dabco)]n (bdc = 1,4-benzendicarboxylate; dabco = 1,4-diazabicyclo(2.2.2)octane). A single pore model reproduces the unit cell of the evacuated MOF system while a 3×3 grid model is necessary to provide good agreement with the observed pronounced structural changes upon adsorption of either dimethylformamide or benzene

Integration of Ligand Field Molecular Mechanics in Tinker

The ligand field molecular mechanics (LFMM) method for transition-metal complexes has been integrated in Tinker, an easily available and popular molecular modeling software package. The capability to calculate LFMM potentials has been provided by extending the functional forms of the Tinker package as well as by integrating routines for calculating the ligand field stabilization energy (LFSE), which is central to LFMM. The capabilities of the implementation are illustrated by both static calculations on the two spin states of [Fe­(NH₃)₆]²⁺ and on [Cu­(NH₃)_<i>m</i>]²⁺ (<i>m</i> = 4, 5, 6) and dynamic (LFMD) simulations of an FeN₆-type spin-crossover compound. In addition to showing that results obtained with the Tinker-LFMM implementation are consistent with those of experiment and other computational methods and programs, we note that whereas LFMM is able to handle the conventional tetragonal Jahn–Teller distortion of the bond distances in [Cu­(NH₃)₆]²⁺, the LFSE term is also necessary in order to obtain even qualitatively correct coordination geometries for the two lower-coordinate copper complexes