Decoding dominant interaction patterns in halogenated dimers: A journey from halogen bonding to Van der Waals interactions

Halogen bonds play a pivotal role in molecular recognition and self-assembly processes. In this work, we aim to provide a balanced understanding of diverse non-covalent interactions, from halogen bonding to van der Waals interactions in homodimeric complexes of fifteen halogenated molecules, represented as R-X (R = H, F, CH3, CF3, CH2CH; X = Cl, Br, I). Here, a meticulously designed sampling and optimization protocol is applied to generate a diverse set of molecular configurations and subsequently optimize them to identify dominant interaction patterns. The clustering algorithm revealed distinct interaction patterns that emerge from the 30,000 optimized structures. The proportion of each cluster and the energy stability are also reported. Dimensionality reduction techniques are employed to visualize these interaction modes, providing a clear representation of the underlying patterns. Notably, the distribution shape of the closest contact distance within these complexes is profoundly influenced by their substituent group. The interplay between halogen bonds and other non-covalent interactions is clearly identified. The scalar relativistic effects were evaluated for the closest contact distances with the ANOVA test. They did not show significant bias from their non-relativistic geometries. We hope these findings offer a holistic view of the intricate inter-molecular landscapes of halogenated dimers, paving the way for their informed utilization in various scientific and technological applications.