scholarly journals Dynamic chiral self-recognition in aromatic dimers of styrene oxide revealed by rotational spectroscopy

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Sérgio R. Domingos ◽  
Cristóbal Pérez ◽  
Nora M. Kreienborg ◽  
Christian Merten ◽  
Melanie Schnell
Keyword(s):  
Styrene Oxide ◽  
Intermolecular Forces ◽  
Molecular Structures ◽  
Conformational Space ◽  
Rotational Spectroscopy ◽  
Self Recognition ◽  
Quantum Chemistry Calculations ◽  
Conformational Landscape ◽  
Non Covalent Interactions ◽  
Covalent Interactions

AbstractChiral molecular recognition is a pivotal phenomenon in biomolecular science, governed by subtle balances of intermolecular forces that are difficult to quantify. Non-covalent interactions involving aromatic moieties are particularly important in this realm, as recurring motifs in biomolecular aggregation. In this work, we use high-resolution broadband rotational spectroscopy to probe the dynamic conformational landscape enclosing the self-pairing topologies of styrene oxide, a chiral aromatic system. We reach a definite assignment of four homochiral and two heterochiral dimers using auxiliary quantum chemistry calculations as well as structure-solving methods based on experimental isotopic information. A complete picture of the dimer conformational space is obtained, and plausible routes for conformational relaxation are derived. Molecular structures are discussed in terms of conformational flexibility, the concerted effort of weak intermolecular interactions, and their role in the expression of the molecular fit.

Exploring the non-covalent interactions behind the formation of amine–water complexes: The case of the N-allylmethylamine monohydrate

2021 ◽  
Author(s):  
Weslley Guilherme Dias de Paiva Silva ◽  
Tamanna Poonia ◽  
Jennifer van Wijngaarden
Keyword(s):  
Quantum Chemistry ◽  
Rotational Spectroscopy ◽  
Quantum Chemistry Calculations ◽  
Conformational Landscape ◽  
Non Covalent Interactions ◽  
First Time ◽  
Covalent Interactions

The conformational landscape of the monohydrated complex of N-allylmethylamine (AMA–w) was investigated for the first time using rotational spectroscopy from 8–20 GHz and quantum chemistry calculations. From a total of...

scholarly journals 1,3,5-Triaza-7-Phosphaadamantane (PTA) as a 31P NMR Probe for Organometallic Transition Metal Complexes in Solution

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1390 ◽  
Author(s):  
Ilya G. Shenderovich
Keyword(s):  
Chemical Shift ◽  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Density Functional ◽  
Molecular Structures ◽  
Basis Sets ◽  
Functional Theory ◽  
Non Covalent Interactions ◽  
Covalent Interactions

Due to the rigid structure of 1,3,5-triaza-7-phosphaadamantane (PTA), its 31P chemical shift solely depends on non-covalent interactions in which the molecule is involved. The maximum range of change caused by the most common of these, hydrogen bonding, is only 6 ppm, because the active site is one of the PTA nitrogen atoms. In contrast, when the PTA phosphorus atom is coordinated to a metal, the range of change exceeds 100 ppm. This feature can be used to support or reject specific structural models of organometallic transition metal complexes in solution by comparing the experimental and Density Functional Theory (DFT) calculated values of this 31P chemical shift. This approach has been tested on a variety of the metals of groups 8–12 and molecular structures. General recommendations for appropriate basis sets are reported.

Disentangling the complex network of non-covalent interactions in fenchone hydrates via rotational spectroscopy and quantum chemistry

2021 ◽  
Author(s):  
Mhamad Chrayteh ◽  
Ecaterina Burevschi ◽  
Donatella Loru ◽  
Therese R. Huet ◽  
Pascal Dréan ◽  
...  
Keyword(s):  
Quantum Chemistry ◽  
Computational Chemistry ◽  
Complex Network ◽  
Microwave Spectroscopy ◽  
Rotational Spectroscopy ◽  
Non Covalent Interactions ◽  
First Time ◽  
Covalent Interactions

The hydrates of the monoterpenoid fenchone (C10H16O).(H2O)n (n=1,2,3) were investigated both by computational chemistry and microwave spectroscopy. Two monohydrates, three dihydrates and for the first time three trihydrates have been...

scholarly journals Non covalent interactions stabilizing the chiral dimer of CH2ClF: a rotational study

2019 ◽  
Vol 21 (7) ◽  
pp. 3695-3700 ◽  
Author(s):  
Laura B. Favero ◽  
Assimo Maris ◽  
Sonia Melandri ◽  
Paolo Ottaviani ◽  
Walther Caminati
Keyword(s):  
Spectral Analysis ◽  
Gas Phase ◽  
Rotational Spectroscopy ◽  
Non Covalent Interactions ◽  
Covalent Interactions

Two C–H⋯Cl–C and one C–H⋯F–C bonds stabilize (by 5.9 kJ mol−1) the dimer of chlorofluoromethane observed by rotational spectroscopy in the gas phase. The spectral analysis is complicated by the quadrupolar effects of the two nonequivalent Cl nuclei.

scholarly journals Decoding conformational polymorphism in organic substances

2014 ◽  
Vol 70 (a1) ◽  
pp. C557-C557
Author(s):  
Ahmed Orlando ◽  
Laura Loconte ◽  
Emanuele Ortoleva ◽  
Carlo Gatti ◽  
Leonardo Lo Presti
Keyword(s):  
Molecular Conformation ◽  
Crystal Packing ◽  
X Ray Diffraction ◽  
Self Recognition ◽  
Crystallization Conditions ◽  
Polymorphic Forms ◽  
Non Covalent Interactions ◽  
Cohesive Energies ◽  
Covalent Interactions

Different polymorphs have different intensive physical properties and it is still impossible to predict from scratch if a change in the crystallization conditions will result in different crystal structures or not. In this contribution, possible correlations are highlighted among charge density features, molecular conformation and interaction energetics in the two known polymorphic forms of (DTC)[1,2], an isothiazole β-sultamic derivative. A tentative rationale is provided for the relative stability of the two forms on the basis of their different self-recognition patterns. Both polymorphs crystallize in the same P21/n space group and show very different non-covalent networks of weak C-H–X (X = N,O,π) interactions due to the dissimilar conformation of the asymmetric units (ASU). Accurate multi-temperature (100 K ≤ T ≤ 298 K) single-crystal X-Ray diffraction experiments were carried out and the evolution of crystal packing and self-recognition energetics were monitored through periodic quantum-mechanical calculations at fixed geometries. Preliminary results show that dispersive/repulsive and electrostatic non-covalent interactions dominate the crystal packing in both polymorphs. At T=100 K the form A have a tighter packing, as it shows a greater propensity in being involved in H bonds than B (see the Hirshfeld surface fingerprint plots[3] of forms A -left- and B -right- here reported). This reflects in greater density, whereas the estimated DFT cohesive energies of the two forms are similar. DTC has enough molecular flexibility to access various favourable arrangements during the nucleation, as the interconversion between the A and B conformers in the gas phase takes place with a very small activation energy. The possible role of the solvent in favouring either of the two observed conformations is discussed.

scholarly journals Assessing the Sequence Dependence of Pyrimidine-Pyrimidone (6-4) Photoproduct in a Duplex Double-Stranded DNA: A Challenge for Microsecond Range Simulation

2020 ◽  
Author(s):  
Natacha Gillet ◽  
Alessio Bartocci ◽  
Elise Dumont
Keyword(s):  
Dna Bending ◽  
Dna Recognition ◽  
Structural Reorganization ◽  
Sequence Dependence ◽  
Double Stranded Dna ◽  
Conformational Landscape ◽  
Non Covalent Interactions ◽  
Dynamics Simulations ◽  
Close Sequence ◽  
Covalent Interactions

Sequence dependence of the (6-4)photoproduct dynamics when embedded in six 25-bp duplexes is evaluated along extensive unbiased and enhanced (replica exchange with solute tempering, REST2) molecular dynamics simulations. The structural reorganization as the central pyrimidines become covalently tethered is traced back in terms of non-covalent interactions, DNA bending and extrusion of adenines of the opposite strands. The close sequence pattern impacts the conformational landscape around the lesion, inducing a different upstream and downstream flexibilities. Moreover, REST2 simulations allow to probe structures possibly important for damaged DNA recognition. <br>

scholarly journals Catalytic Enantioselective Synthesis of Heterocyclic Vicinal Fluoroamines Using Asymmetric Protonation: A Method Development and Mechanistic Study

2020 ◽  
Author(s):  
Matthew Ashford ◽  
Chao Xu ◽  
john molloy ◽  
Cameron Carpenter-Warren ◽  
Alexandra Slawin ◽  
...  
Keyword(s):  
Method Development ◽  
Data Bank ◽  
Enantioselective Synthesis ◽  
Mechanistic Study ◽  
Type Analysis ◽  
Conformational Landscape ◽  
Non Covalent Interactions ◽  
Chiral Bronsted Acid ◽  
Covalent Interactions ◽  
Insight Into

<div> <div> <div> <p>A catalytic enantioselective synthesis of heterocyclic vicinal fluoroamines is reported. A chiral Brønsted acid promotes aza-Michael addition to fluoroalkenyl heterocycles to give a prochiral enamine intermediate, which undergoes asymmetric protonation upon rearomatization. The reaction accommodates a range of azaheterocycles and nucleophiles, generating the C–F stereocenter in high enantioselectivity, and is also amenable to stereogenic C–CF3 bonds. Extensive DFT calculations have provided insight into the reaction mechanism and the origin of catalyst selectivity. Crystal structure data shows the dominance of non-covalent interactions in the core structure conformation, enabling modulation of the conformational landscape. Ramachandran-type analysis of conformer distribution and protein data bank mining has indicated benzylic fluorination using this approach has potential for improved potency in several marketed drugs. </p> </div> </div> </div>

The axial/equatorial conformational landscape and intramolecular dispersion: new insights from the rotational spectra of monoterpenoids

2019 ◽  
Vol 21 (47) ◽  
pp. 26111-26116 ◽  
Author(s):  
Donatella Loru ◽  
Annalisa Vigorito ◽  
Andreia F. M. Santos ◽  
Jackson Tang ◽  
M. Eugenia Sanz
Keyword(s):  
Quantum Chemistry ◽  
Rotational Spectroscopy ◽  
Theoretical Methods ◽  
Rotational Spectra ◽  
Quantum Chemistry Calculations ◽  
Conformational Landscape

Using rotational spectroscopy and quantum chemistry calculations, we show that intramolecular dispersion stabilises the axial conformers of monoterpenoids, and that an accurate account of these interactions is challenging for theoretical methods.

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