We present the CHAL336 benchmark set-the most comprehensive database for the assessment of chalcogen-bonding (CB) interactions. After careful selection of suitable systems and identification of three high-level reference methods, the set comprises 336 dimers each consisting of up to 49 atoms and covers both σ-and π-hole interactions across four categories: chalcogen-chalcogen, chalcogen-π, chalcogen-halogen, and chalcogen-nitrogen interactions. In a subsequent study of DFT methods, we re-emphasize the need for using proper London dispersion corrections when treating noncovalent interactions. We also point out that the deterioration of results and systematic overestimation of interaction energies for some dispersion-corrected DFT methods does not hint at problems with the chosen dispersion correction, but is a consequence of large density-driven errors. We conclude this work by performing the most detailed DFT benchmark study for CB interactions to date. We assess 109 variations of dispersion-corrected and -uncorrected DFT methods, and carry out a detailed analysis of 80 of them. Double-hybrid functionals are the most reliable approaches for CB interactions, and they should be used whenever computationally feasible.The best three double hybrids are SOS0-PBE0-2-D3(BJ), revDSD-PBEP86-D3(BJ), and B2NCPLYP-D3(BJ). The best hybrids in this study are ωB97M-V, PW6B95-D3(0), and PW6B95-D3(BJ). We do not recommend using the popular B3LYP functional nor the MP2 approach, which have both been frequently used to describe CB interactions in the past. We hope to inspire a change in computational protocols surrounding CB interactions that leads away from the commonly used, popular methods to the more robust and accurate ones recommended herein. We would also like to encourage method developers to use our set for the investigation and reduction of density-driven errors in new density functional approximations. File list (5) download file view on ChemRxiv CHAL336.pdf (3.01 MiB) download file view on ChemRxiv CHAL336_SI_part1.pdf (1.01 MiB) download file view on ChemRxiv CHAL336_SI_part2_structures.zip (1.95 MiB) download file view on ChemRxiv CHAL336_SI_part3_refvalues.zip (78.17 KiB) download file view on ChemRxiv CHAL336_SI_part4_DFTMP2data.zip (0.90 MiB)

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A number of derivatives of benzisoselenazolinones, including the drug ebselen, have been synthesized, and their interactions with various nitrogen bases characterized through X-ray crystallography.

Molecular rotors exhibit fluorescence enhancement in a confined environment and thus have been used extensively in biological imaging. However, many typical molecular rotors suffer from small Stokes shift and self-aggregation...

An o-nitro-O-aryl oxime was observed to exhibit a short O⋯O contact, which exhibited characteristics consistent with a chalcogen bond.