DFT conformational study of banana-shaped mesogens

Cacelli, Ivo; Prampolini, Giacomo

doi:10.1016/j.chemphys.2005.03.003

Cited by 22 publications

(31 citation statements)

References 19 publications

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“…Consequently, the two lateral wings experience a different orientation with respect to the magnetic field. This finding is in agreement with quantum mechanical computations for the five-ring molecule, [33] as well as with the observed behaviour of two banana-shaped sub-units (three-ring probes) diluted in LC solvents. [10] 2) The inner rings appear to be more ordered than the outer rings.…”

supporting

confidence: 90%

“…[31] Indeed, torsional energy profiles have been recently successfully studied on phenyl benzoate [32] and banana-shaped molecular cores, [33] by employing DFT techniques rather than the MP2 method. The former are generally preferred in view of the smaller basis set sensitiveness and, therefore, of their computational convenience.…”

Section: Methodsmentioning

confidence: 99%

“…This behaviour is also confirmed by the calculations reported in refs. [10,33], which show that the energy surface potential of the external rings is extremely flat as a function of dihedral angles. As recent computations have shown, [33] the more oriented rings are those on the lateral wing closer to the chlorine atom.…”

mentioning

confidence: 97%

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Banana‐Shaped Molecules Peculiarly Oriented in a Magnetic Field:²H NMR Spectroscopy and Quantum Mechanical Calculations

et al. 2007

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The orientational properties of the banana-shaped liquid crystal 4-chloro-1,3-phenylenebis{4-[4'-(10-undecenyloxy)]benzoyloxy} benzoate (ClPbis11BB) are reported in the nematic phase under the effect of an external magnetic field. A new hypothesis, which states that the central ring of the aromatic core is oriented perpendicularly to the external magnetic field, is proposed. In support of this hypothesis, a series of studies based on (2)H NMR spectroscopy, both in the bulk and in solution, are discussed. (2)H NMR measurements on three selectively deuterium-labelled isotopomers are presented, together with DFT results from B3LYP/cc-pvDz calculations performed on the aromatic core. The rather flat shape of the investigated intramolecular energy surface allows for several different conformations to be populated, the computed magnetic susceptibilities of which are consistent with the proposed hypothesis of peculiar orientation of banana-shaped molecules. Moreover, the orientation of the magnetic susceptibility tensor is shown to be strongly dependent on the internal conformation of the banana-shaped molecules.

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confidence: 90%

Section: Methodsmentioning

confidence: 99%

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Banana‐Shaped Molecules Peculiarly Oriented in a Magnetic Field:²H NMR Spectroscopy and Quantum Mechanical Calculations

et al. 2007

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“…The overall shape of the aromatic core depends on the value of the dihedral angles flanking the central aromatic ring, which are denoted as c 24 (C 9 ÀNÀC 10 ÀC 11 ) and c 25 (C 13 ÀC 14 ÀC=O). A special role of the geometry around the central ring, which is determined by the constraints imposed by the local chemical structure, [49] is recognized as a typical feature of bent-core mesogens. [26,27] According to previous computations, [31,46] the torsional potential relative to the dihedral angle c 24 is characterized by two degenerate minima (c 24~AE 458); for each of them four states were identified for c 25 (~AE 158 and~AE 1658).…”

Section: Theoretical and Computational Methodsmentioning

confidence: 99%

From the Molecular Structure to Spectroscopic and Material Properties: Computational Investigation of a Bent‐Core Nematic Liquid Crystal

et al. 2014

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We present a computational investigation of the nematic phase of the bent-core liquid crystal A131. We use an integrated approach that bridges density functional theory calculations of molecular geometry and torsional potentials to elastic properties through the molecular conformational and orientational distribution function. This unique capability to simultaneously access different length scales enables us to consistently describe molecular and material properties. We can reassign (13)C NMR chemical shifts and analyze the dependence of phase properties on molecular shape. Focusing on the elastic constants we can draw some general conclusions on the unconventional behavior of bent-core nematics and highlight the crucial role of a properly-bent shape.

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“…flexibility), and the detailed effect of electrostatic charges as computed from ab-initio calculations on specific molecules (see e.g. [142]) that would be difficult to tackle with theory or simpler potentials. For instance, in [59] the same atomistic model devoid of electrostatic charges (e.g.…”

Section: Multi-site Modelsmentioning

confidence: 99%

Computer simulations of biaxial nematics

Berardi

Muccioli

Orlandi

et al. 2008

J. Phys.: Condens. Matter

120

108

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Abstract. Biaxial nematic (N b ) liquid crystals are a fascinating condensed matter phase that has baffled for more than thirty years scientists engaged in the challenge of demonstrating its actual existence, and which has only recently been experimentally found. During this period computer simulations of model N b have played an important role, both in providing the basic physical properties to be expected from these systems, and in giving clues about the molecular features essential for the thermodynamic stability of N b phases. However, simulations studies are expected to be even more crucial in the future for unravelling the structural features of biaxial mesogens at molecular level, and for helping in the design and optimisation of devices towards the technological deployment of N b materials. This review article gives an overview of the simulation work performed so far, and relying on the recent experimental findings, focusses on the still unanswered questions which will determine the future challenges in the field.

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DFT conformational study of banana-shaped mesogens

Cited by 22 publications

References 19 publications

Banana‐Shaped Molecules Peculiarly Oriented in a Magnetic Field:²H NMR Spectroscopy and Quantum Mechanical Calculations

Banana‐Shaped Molecules Peculiarly Oriented in a Magnetic Field:²H NMR Spectroscopy and Quantum Mechanical Calculations

From the Molecular Structure to Spectroscopic and Material Properties: Computational Investigation of a Bent‐Core Nematic Liquid Crystal

Computer simulations of biaxial nematics

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DFT conformational study of banana-shaped mesogens

Cited by 22 publications

References 19 publications

Banana‐Shaped Molecules Peculiarly Oriented in a Magnetic Field:2H NMR Spectroscopy and Quantum Mechanical Calculations

Banana‐Shaped Molecules Peculiarly Oriented in a Magnetic Field:2H NMR Spectroscopy and Quantum Mechanical Calculations

From the Molecular Structure to Spectroscopic and Material Properties: Computational Investigation of a Bent‐Core Nematic Liquid Crystal

Computer simulations of biaxial nematics

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Product

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Banana‐Shaped Molecules Peculiarly Oriented in a Magnetic Field:²H NMR Spectroscopy and Quantum Mechanical Calculations

Banana‐Shaped Molecules Peculiarly Oriented in a Magnetic Field:²H NMR Spectroscopy and Quantum Mechanical Calculations