Effect of adjoining aromatic ring upon excited state proton transfer, o-hydroxybenzaldehyde

C̆uma, Martin; Scheiner, Steve; Kar, Tapas

doi:10.1016/s0166-1280(98)00477-1

Cited by 83 publications

(61 citation statements)

References 52 publications

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“…Nevertheless, in spite of this, some additive schemes leading to numbers understood as interaction energies have been proposed. Among them, the so-called open-closed method [45,46] seems to be both the most popular [26][27][28][29][45][46][47][48][49][50][51][52][53][54][55][56][57][58] and straightforward. According to this method, the interaction energy is just a difference between total energies of the closed form of a molecule, i.e.…”

Section: Energy Of An Intramolecular Interactionmentioning

confidence: 99%

Strength of Si–H ⋯ B charge-inverted hydrogen bonds in 1-silacyclopent-2-enes and 1-silacyclohex-2-enes

Jabłoński

2017

Struct Chem

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It is shown that the H· · · B contacts in 1-silacyclohex-2-enes are clearly stabilizing and strong, whereas those in 1-silacyclopent-2-enes are much weaker. This result is supported by analysis of QTAIM-based parameters and appropriate structural changes taking place upon the open form → closed form transformation and is in full agreement with previous NMR spectroscopic data [Wrackmeyer et al. (2006) Appl Organometal Chem 20:99-105]. Also, the influence of electronic and steric effects originating from the presence of specific substituents on the strength of the H· · · B contacts is discussed in detail. Some problems and ideas associated with the use of the so-called open-closed method utilized in assessing values of interaction energies are discussed in detail. Particular attention is paid to the correct choice of reference open systems. It is shown that their partial geometry optimization leads to reliable values of interaction energies.

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Section: Energy Of An Intramolecular Interactionmentioning

confidence: 99%

Strength of Si–H ⋯ B charge-inverted hydrogen bonds in 1-silacyclopent-2-enes and 1-silacyclohex-2-enes

Jabłoński

2017

Struct Chem

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“…One can take an arithmetical average of the forward and reverse proton transfer barriers as an estimate of what the barrier would be in a hypothetical symmetric variant of this molecule, the socalled E o † . 31 The patterns of these averages, listed in Table VI, eliminate some of the anomalies noted in the asymmetric barriers of either G N or G O . As in the case of the symmetric systems in the upper three sections of for the 1 * state is clearly the lowest at all theoretical levels; adding dynamic correlation to either CIS or CASSCF substantially lowers each barrier.…”

Section: Asymmetric Systemmentioning

confidence: 86%

“…Another theoretical approach predicted the keto as the more stable tautomer of the two, but with a low to nonexistent barrier separating them. 31 The problem is exacerbated by the paucity of experimental information that is accurate and quantitative enough to act as a reliable yardstick by which to measure the performance of the calculations on the excited-state properties of the molecules under study. In the absence of such an experimental gauge, probably the next best test is that of internal consistency: are the theoretical calculations consistent amongst themselves?…”

Section: Introductionmentioning

confidence: 99%

Comparison of methods for calculating the properties of intramolecular hydrogen bonds. Excited state proton transfer

Kar

Scheiner

C̆uma

1999

The Journal of Chemical Physics

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A series of molecules related to malonaldehyde, containing an intramolecular H-bond, are used as the testbed for a variety of levels of ab initio calculation. Of particular interest are the excitation energies of the first set of valence excited states, n* and *, both singlet and triplet, as well as the energetics of proton transfer in each state. Taking coupled cluster results as a point of reference, configuration interaction-singles-second-order Møller-Plesset ͑CIS-MP2͒ excitation energies are too large, as are CIS to a lesser extent, although these approaches successfully reproduce the order of the various states. The same may be said of complete active space self-consistent-field ͑CASSCF͒, which is surprisingly sensitive to the particular choice of orbitals included in the active space. Complete active space-second-order perturbation theory ͑CASPT2͒ excitation energies are rather close to coupled cluster singles and doubles ͑CCSD͒, as are density functional theory ͑DFT͒ values. CASSCF proton transfer barriers are large overestimates; the same is true of CIS to a lesser extent. MP2, CASPT2, and DFT barriers are closer to coupled cluster results, although yielding slight underestimates.

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“…Here, the gain in energy from the RAHB unit competes with the gain in energy from aromatic resonance of the fused phenyl ring. In salicylaldehyde, tautomer IX is more stable than XII that is no longer aromatic (Scheme 2) [19,20]. However, the molecular geometries determined via electron diffraction in conjunction with DFT calculations reveal that also in these systems the resonance structure X has strong contributions to the overall resonance hybride so that the hydrogen bond is also resonance-assisted [19,21,22].…”

Section: Introductionmentioning

confidence: 99%

Electronic and Molecular Structures of Heteroradialenes: A Combined Synthetic, Computational, Spectroscopic, and Structural Study Identifying IR Spectroscopy as a Simple but Powerful Experimental Probe

Richthofen

Feldscher

Lippert

et al. 2013

Zeitschrift Für Naturforschung B

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The vicinity of a hydrogen bond donor (O-H) and a hydrogen bond acceptor (C=O or C=N-R) in salicylaldehydes and ortho-Schiff bases results in significant structural variations compared to the monosubstituted derivatives that are reflected in the electronic structure and thus in the spectroscopic properties. This interplay between intramolecular hydrogen bonding and multicenter π-electron delocalization is the origin of the concept of resonance-assisted hydrogen bonding (RAHB). Herein, the complexity is extended from one hydrogen bond donor-acceptor pair in salicylaldehyde and ortho-Schiff bases to three hydrogen bond donor-acceptor pairs in 2,4,6-tricarbonyl-and 2,4,6-triimine-substituted phloroglucinols (1,3,5-trihydroxybenzene), respectively. To evaluate the changes in the molecular and electronic structures, we have performed a comprehensive computational, spectroscopic, and structural study starting from monosubstituted benzene derivatives as references over ortho-disubstituted derivates to the sixfold-substituted derivatives. Whereas in salicylaldehydes, ortho-Schiff bases, and 2,4,6-tricarbonyl-phloroglucinols the phenolic O-protonated tautomers represent the energy minima, the N-protonated tautomers represent the energy minima in 2,4,6-triiminephloroglucinols. The analysis provides a keto-enamine resonance structure with six exocyclic double bonds to be dominant for these species reminiscent of [6]radialenes, which were termed heteroradialenes. These heteroradialenes are non-aromatic alicycles. However, the predominance of this resonance structure does not represent a sudden change going from the 2,4,6-tricarbonyl-to the 2,4,6-triimine-phloroglucinols, but a gradual increase of analogous resonance structure contributions is observed even in salicylaldehyde and ortho-Schiff bases demonstrating some hetero-orthoquinodimethane character. These changes are, besides in the molecular structures, well reflected in the IR spectra, which can therefore be used as a simple tool to probe the electronic structures in these systems. Interruption of the delocalized π system supporting the intramolecular hydrogen bond, i. e. going from 2,4,6-triimine-to 2,4,6-triamine-substituted phloroglucinols, reestablishes an O-protonated aromatic phloroglucinol system.

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Effect of adjoining aromatic ring upon excited state proton transfer, o-hydroxybenzaldehyde

Cited by 83 publications

References 52 publications

Strength of Si–H ⋯ B charge-inverted hydrogen bonds in 1-silacyclopent-2-enes and 1-silacyclohex-2-enes

Strength of Si–H ⋯ B charge-inverted hydrogen bonds in 1-silacyclopent-2-enes and 1-silacyclohex-2-enes

Comparison of methods for calculating the properties of intramolecular hydrogen bonds. Excited state proton transfer

Electronic and Molecular Structures of Heteroradialenes: A Combined Synthetic, Computational, Spectroscopic, and Structural Study Identifying IR Spectroscopy as a Simple but Powerful Experimental Probe

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