Tatiana Nikolaeva | Searcharxiv

arXiv2026

The BOS-TMC Dataset: DFT Properties of 159k Experimentally Characterized Transition Metal Complexes Spanning Multiple Charge and Spin States

We present the Boston Open-Shell Transition Metal Complex (BOS-TMC) dataset, a set of density functional theory (DFT) properties for 159k experimentally characterized mononuclear transition metal complexes (TMCs) in multiple spin states with a range of formal charges derived from the Cambridge Structural Database (CSD). To curate this set, we carried out an iterative procedure to confidently assign overall TMC charge. From this information, we then obtained properties in up to three spin states, i.e., low-, intermediate-, and high-spin for 3d metals and low- and intermediate-spin for 4d and 5d metals, depending on compatibility with the metal electron configuration, for a total of 343.8k TMC/spin combinations. At odds with prior sets, we preserved experimental heavy-atom coordinates in these structures during optimization. We report all properties using PBE0/def2-TZVP single-point energies on these structures. We introduce a scheme for computing metal-spin-dependent atomization energies, which we report for each TMC. Alongside electronic energies, we report up to seven additional properties including: HOMO, LUMO, HOMO-LUMO gap, atomic partial charges, dipole moments, atomization energies, and spin-splitting energies for a total of over 2.9M TMC-associated properties. For a representative subset of over 10k complexes chosen based on size, we evaluate the sensitivity of computed properties to exchange-correlation (xc) functional choice from a set of twelve xcs spanning rungs of "Jacob's ladder", highlighting hotspots of TMC space that have the greatest uncertainty. In comparison to prior transition-metal datasets, BOS-TMC is both larger and more diverse in terms of charge and spin configurations and, as a result, more diverse in its range of properties. This dataset is expected to provide a high-fidelity foundation for machine-learning model development, DFT benchmarking, and exploration.

physics.chem-ph↗

arXiv2020

Direct evidence of stress-induced chain proximity in a macromolecular complex

The mechanical properties of many supramolecular materials are often determined by non-covalent interactions that arise from an interplay between chemical composition and molecular microstructural organization. The reversible nature of non-covalent interactions gives supramolecular materials responsive properties that are otherwise difficult to obtain, such as becoming rigid as a response to mechanical stress. How exactly non-covalent interactions emerge from microstructure, how they might change in response to applied force or deformation is not understood. Here we combine Nuclear Magnetic Resonance (NMR) and rheology to directly probe the role of chain proximity in polymer complexes. We observe an increase in chain proximity in response to imposed flow, which we hypothesize to originate from enhanced hydrogen bonding. The chain proximity is directly correlated to rod climbing and shear banding. Flow persists only when applied stresses are low, suggesting a stress-induced thickening mechanism. We verify that hydrogen bond disruptors can turn off both the non-trivial flow behavior and the spectroscopic evidence of chain proximity. The combined rheo-NMR approach shows that it is possible to directly observe the molecular origins behind supramolecular mechanics, paving the way for further study into mechano-chemical properties of supramolecular materials.

cond-mat.soft↗