Abstract:The procedure leading to the first HyDRA blind challenge for the prediction of water donor stretching vibrations in monohydrates of organic molecules is described. A training set of 10 monohydrates with experimentally known and published water donor vibrations is presented and a test set of 10 monohydrates with unknown or unpublished water donor vibrational wavenumbers is described together with relevant background literature. The rules for data submissions from computational chemistry groups are outlined and … Show more
“…Still, the continuous improvement and conceptualization of theoretical approaches, aiming to predict experimental outcome without any prior knowledge of the desired result, calls for the joint efforts of theoreticians and experimentalists. In this respect, several blind challenges in numerical quantum chemistry have already been successfully established, such as the GöBenCH [3,4], HyDRA [5], Fe-MAN [6], or the SAMPL6 [7,8] benchmarks. These challenges target important physical chemical properties, such as van der Waals interactions, hydrogen bonding, and proton transfer, to identify methodological limitations and bottlenecks, and allow to push forward the development of new methodologies and composite schemes.…”
High-resolution spectroscopy techniques play a pivotal role to validate and efficiently benchmark available methods from quantum chemistry. In this work, we analyzed the microwave spectrum of ethyl butyrate within the...
“…Still, the continuous improvement and conceptualization of theoretical approaches, aiming to predict experimental outcome without any prior knowledge of the desired result, calls for the joint efforts of theoreticians and experimentalists. In this respect, several blind challenges in numerical quantum chemistry have already been successfully established, such as the GöBenCH [3,4], HyDRA [5], Fe-MAN [6], or the SAMPL6 [7,8] benchmarks. These challenges target important physical chemical properties, such as van der Waals interactions, hydrogen bonding, and proton transfer, to identify methodological limitations and bottlenecks, and allow to push forward the development of new methodologies and composite schemes.…”
High-resolution spectroscopy techniques play a pivotal role to validate and efficiently benchmark available methods from quantum chemistry. In this work, we analyzed the microwave spectrum of ethyl butyrate within the...
“…As monohydrates are vibrationally 15 far less characterised than rotationally 16,17 , the topic also leaves enough playground for blind testing. As the layout of this blind test has been described extensively before, 18 we refrain from repeating the experimental tools [19][20][21] and caveats. 22 As detailed in our first publication introducing the challenge 18 , a set of 10 hydrate systems were selected as 'training set', in order for the participants to fine tune or validate beforehand their approaches.…”
Section: Introductionmentioning
confidence: 99%
“…As the layout of this blind test has been described extensively before, 18 we refrain from repeating the experimental tools [19][20][21] and caveats. 22 As detailed in our first publication introducing the challenge 18 , a set of 10 hydrate systems were selected as 'training set', in order for the participants to fine tune or validate beforehand their approaches. The latter consisted of: acetone (ACE), acetophenone (APH), 1,2,4,5-tetrafluorobenzene (TFB), 1-phenylethanol (POH), imidazole (IMZ), aniline (ANL), dibenzofuran (DBZ), di-tert-butyl nitroxide (DBN), o-cyanophenol (OCP) and cyclobutanone (CBU).…”
Vibrational spectroscopy in supersonic jet expansions is a powerful tool to assess molecular aggregates in close to ideal conditions for the benchmarking of quantum chemical approaches. The low temperatures achieved as well as the absence of environment effects allow for a direct comparison between computed and experimental spectra. This provides potential benchmarking data which can be revisited to hone different computational techniques, and it allows for the critical analysis of procedures under the setting of a blind challenge. In the latter case, the final result is unknown to modellers, providing an unbiased testing opportunity for quantum chemical models. In this work, we present the spectroscopic and computational results for the first HyDRA blind challenge. The latter deals with the prediction of water donor stretching vibrations in monohydrates of organic molecules. This edition features a test set of 10 systems. Experimental water donor OH vibrational wavenumbers for the vacuum-isolated monohydrates of formaldehyde, tetrahydrofuran, pyridine, tetrahydrothiophene, trifluoroethanol, methyl lactate, dimethylimidazolidinone, cyclooctanone, trifluoroacetophenone and 1-phenylcyclohexane-cis-1,2-diol are provided. The results of the challenge show promising predictive properties in both purely quantum mechanical approaches as well as regression and other machine learning strategies.
“…The drastically reduced complexity of the systems under investigation then allows for their characterization in great detail. Thus, IR, Raman, and microwave spectroscopy, together with quantum chemical calculations, succeeded in unraveling the different conformers populated in R F3 OH monomers, dimers, and trimers. − Moreover, these methods also afforded detailed structural and energetic information on the complexes of R F3 OH with water, , which has also been included in a recent blind challenge for computational chemistry . The primary interaction between the individual molecules in these aggregates corresponds to hydrogen bonding.…”
Negative-ion mode electrospray ionization
of solutions of ethanol (RF0OH), 2-fluoroethanol (RF1OH), 2,2-difluoroethanol (RF2OH), and/or 2,2,2-trifluoroethanol
(RF3OH) produces anionic dimers of the types (RFn
O)2H– and (RFn
O)(RFn+1O)H–. The exchange reactions of these anionic dimers with the neutral
alcohols are examined in a quadrupole-ion trap to extract kinetic
data, from which the reaction Gibbs energies are obtained. In all
cases, the formation of anionic dimers containing the more highly
fluorinated alcohols is favored. Quantum chemical calculations confirm
this trend and, besides affording structural data, also determine
the dissociation energies of the anionic dimers. These dissociation
energies are much higher than those of the corresponding neutral dimers
and increase further for the more highly fluorinated alcohols due
to the stronger hydrogen-bond donor ability of the latter. The present
results on the interaction of individual alkoxide anions and neutral
alcohol molecules contribute to a better understanding of the association
of the fluorinated alcohols in solution.
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