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Bödecker M, Mihrin D, Suhm MA, Wugt Larsen R. Regularities and Anomalies in Neon Matrix Shifts of Hydrogen-Bonded O-H Stretching Fundamentals. J Phys Chem A 2024; 128:7124-7136. [PMID: 39155731 PMCID: PMC11372756 DOI: 10.1021/acs.jpca.4c03468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/20/2024]
Abstract
O-H bond stretching vibrations in hydrogen-bonded complexes embedded into cryogenic neon matrices are subtly downshifted from cold gas phase reference wavenumbers. To the extent that this shift is systematic, it enables neon matrices as more universally applicable spectroscopic benchmark environments for quantum chemical predictions. Outliers are indicative of either an assignment problem in one of the two cryogenic experiments or they reveal interesting dynamics or structural effects on the complexes as a function of the environment. We compile 6 literature-known pairs of experimental data in jet and neon matrix expansions and realize a 6-fold expansion of that number through targeted matrix isolation and/or slit jet expansion spectroscopy presented in this work. In many cases, the neon matrix shift is less than the uncertainty of the currently best-performing blind quantum chemical predictions for the gas phase, but in specific cases, it may exceed the currently achievable theoretical accuracy. Some evidence for a positive correlation of the matrix shift with the hydrogen bond shift is found, similar to observations for helium nanodroplets. Outliers in particular for water acting as a donor are discussed, and in a few cases they call for a future reinvestigation. Substantial improvement in the correlation of the matrix shift with the hydrogen bond shift is achieved for ketone monohydrates by removing a vibrational resonance. New insights into nitrile hydration isomerism are obtained, and the linear OH stretching spectrum of the jet-cooled ammonia-water complex is presented for the first time. Vibrational spectroscopy in weakly perturbing solid rare gas quantum matrices for the benchmarking of gas phase theory and future explicit theoretical treatments of the quantum matrix environment to better understand the outliers are both encouraged.
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Affiliation(s)
- Margarethe Bödecker
- Institute of Physical Chemistry, University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany
| | - Dmytro Mihrin
- Department of Chemistry, Technical University of Denmark, Kemitorvet 206, 2800 Kgs. Lyngby, Denmark
| | - Martin A Suhm
- Institute of Physical Chemistry, University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany
| | - René Wugt Larsen
- Department of Chemistry, Technical University of Denmark, Kemitorvet 206, 2800 Kgs. Lyngby, Denmark
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Oenen K, Dinu DF, Liedl KR. Determining internal coordinate sets for optimal representation of molecular vibration. J Chem Phys 2024; 160:014104. [PMID: 38180253 DOI: 10.1063/5.0180657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 12/10/2023] [Indexed: 01/06/2024] Open
Abstract
Arising from the harmonic approximation in solving the vibrational Schrödinger equation, normal modes dissect molecular vibrations into distinct degrees of freedom. Normal modes are widely used as they give rise to descriptive vibrational notations and are convenient for expanding anharmonic potential energy surfaces as an alternative to higher-order Taylor series representations. Usually, normal modes are expressed in Cartesian coordinates, which bears drawbacks that can be overcome by switching to internal coordinates. Considering vibrational notations, normal modes with delocalized characters are difficult to denote, but internal coordinates offer a route to clearer notations. Based on the Hessian, normal mode decomposition schemes for a given set of internal coordinates can describe a normal mode by its contributions from internal coordinates. However, choosing a set of internal coordinates is not straightforward. While the Hessian provides unique sets of normal modes, various internal coordinate sets are possible for a given system. In the present work, we employ a normal mode decomposition scheme to choose an optimal set. Therefore, we screen reasonable sets based on topology and symmetry considerations and rely on a metric that minimizes coupling between internal coordinates. Ultimately, the Nomodeco toolkit presented here generates internal coordinate sets to find an optimal set for representing molecular vibrations. The resulting contribution tables can be used to clarify vibrational notations. We test our scheme on small to mid-sized molecules, showing how the space of definable internal coordinate sets can significantly be reduced.
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Affiliation(s)
- Kemal Oenen
- Department of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innrain 80, 6020 Innsbruck, Austria
| | - Dennis F Dinu
- Department of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innrain 80, 6020 Innsbruck, Austria
| | - Klaus R Liedl
- Department of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innrain 80, 6020 Innsbruck, Austria
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Sadowski B, Gryko DT. Dipyrrolonaphthyridinedione - (still) a mysterious cross-conjugated chromophore. Chem Sci 2023; 14:14020-14038. [PMID: 38098709 PMCID: PMC10718078 DOI: 10.1039/d3sc05272a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 11/08/2023] [Indexed: 12/17/2023] Open
Abstract
Dipyrrolonaphthyridinediones (DPNDs) entered the chemical world in 2016. This cross-conjugated donor-acceptor skeleton can be prepared in two steps from commercially available reagents in overall yield ≈15-20% (5 mmol scale). DPNDs can be easily and regioselectively halogenated which opens an avenue to numerous derivatives as well as to π-expansion. Although certain synthetic limitations exist, the current derivatization possibilities provided impetus for numerous explorations that use DPNDs. Structural modifications enable bathochromic shift of the emission to deep-red region and reaching the optical brightness 30 000 M-1 cm-1. Intense absorption and strong emission of greenish-yellow light attracted the interest which eventually led to the discovery of their strong two-photon absorption, singlet fission in the crystalline phase and triplet sensitization. Dipyrrolonaphthyridinedione-based twistacenes broadened our knowledge on the influence of twisting angle on the fate of the molecule in the excited state. Collectively, these findings highlight the compatibility of DPNDs with various applications within organic optoelectronics.
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Affiliation(s)
- Bartłomiej Sadowski
- Centre of New Technologies, University of Warsaw S. Banacha 2c 02-097 Warsaw Poland
| | - Daniel T Gryko
- Institute of Organic Chemistry, Polish Academy of Sciences Kasprzaka 44/52 01-224 Warsaw Poland
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Dinu DF, Bartl P, Quoika PK, Podewitz M, Liedl KR, Grothe H, Loerting T. Increase of Radiative Forcing through Midinfrared Absorption by Stable CO 2 Dimers? J Phys Chem A 2022; 126:2966-2975. [PMID: 35533210 PMCID: PMC9125687 DOI: 10.1021/acs.jpca.2c00857] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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We performed matrix-isolation
infrared (MI-IR) spectroscopy of
carbon dioxide monomers, CO2, and dimers, (CO2)2, trapped in neon and in air. On the basis of vibration
configuration interaction (VCI) calculations accounting for mode coupling
and anharmonicity, we identify additional infrared-active bands in
the MI-IR spectra due to the (CO2)2 dimer. These
bands are satellite bands next to the established CO2 monomer
bands, which appear in the infrared window of Earth’s atmosphere
at around 4 and 15 μm. In a systematic carbon dioxide mixing
ratio study using neon matrixes, we observe a significant fraction
of the dimer at mixing ratios above 300 ppm, with a steep increase
up to 1000 ppm. In neon matrix, the dimer increases the IR absorbance
by about 15% at 400 ppm compared to the monomer absorbance alone.
This suggests a high fraction of the (CO2)2 dimer
in our matrix experiments. In atmospheric conditions, such increased
absorbance would significantly amplify radiative forcings and, thus,
the greenhouse warming. To enable a comparison of our laboratory experiment
with various atmospheric conditions (Earth, Mars, Venus), we compute
the thermodynamics of the dimerization accordingly. The dimerization
is favored at low temperatures and/or high carbon dioxide partial
pressures. Thus, we argue that matrix isolation does not trap the
gas composition “as is”. Instead, the gas is precooled
to 40 K, where CO2 dimerizes before being trapped in the
matrix, already at very low carbon dioxide partial pressures. In the
context of planetary atmospheres, our results improve understanding
of the greenhouse effect for planets of rather thick CO2 atmospheres such as Venus, where a significant fraction of the (CO2)2 dimer can be expected. There, the necessity
of including the mid-IR absorption by stable (CO2)2 dimers in databases used for modeling radiative forcing,
such as HITRAN, arises.
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Affiliation(s)
- Dennis F Dinu
- Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, A-6020 Innsbruck, Austria.,Institute of Physical Chemistry, University of Innsbruck, A-6020 Innsbruck, Austria.,Institute of Materials Chemistry, Technische Universität Wien, A-1060 Vienna, Austria
| | - Pit Bartl
- Institute of Physical Chemistry, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Patrick K Quoika
- Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Maren Podewitz
- Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, A-6020 Innsbruck, Austria.,Institute of Materials Chemistry, Technische Universität Wien, A-1060 Vienna, Austria
| | - Klaus R Liedl
- Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Hinrich Grothe
- Institute of Materials Chemistry, Technische Universität Wien, A-1060 Vienna, Austria
| | - Thomas Loerting
- Institute of Physical Chemistry, University of Innsbruck, A-6020 Innsbruck, Austria
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