Order parameters of α,ω-diphenylpolyenes in a nematic liquid crystal from an integrated computational and C13 NMR spectroscopic approach

Benzi, Caterina; Barone, Vincenzo; Tarroni, Riccardo; Zannoni, Claudio

doi:10.1063/1.2363994

Cited by 6 publications

(3 citation statements)

References 70 publications

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“…There is also evidence from the 13 C NMR spectra of diphenylpolyenes, measured in a thermotropic liquid crystal ZLI-1167 between 354 and 307 K, showing a loss of planarity due to the rotation of the two phenyl groups, as reported by Benzi et al [12], and the spectra of DPH, dissolved in 2-methyl-tetrahydrofuran and measured at 323, 293, 268, 238, 208, and 188 K, as reported by Catalán et al [13].…”

Section: Introductionsupporting

confidence: 67%

The Photophysics of Diphenyl Polyenes Analyzed by Their Solvatochromism

Catalán,

Hopf

2024

Liquids

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The solvent-dependent intensity changes in the first UV/Vis absorption band of the three polyenes DPH, DPHb, and ttbP3 dissolved in a hydrocarbon solvent with temperature allow for the conclusion that, at temperatures above 233 K, the two phenyl groups of DPH are rotated out-of-plane to yield a non-coplanar molecular structure. This leads to the conclusion that DPH becomes increasingly less coplanar as the temperature rises above 233 K. When the phenyl groups rotate out-of-plane, the polarizability decreases, and the energy of the first electronic transition increases by an extra value. Therefore, below 233 K, the correlation lines between the absorption energy of the 0–0 component of the UV/Vis absorption band and the solvent polarizability, as measured by the SP values, show bilinear behavior. The unexpected behavior shown by DPH dissolved in tetrachloro- and dichloromethane is discussed. We dedicate this research as a tribute to the very important contribution to the solvent effect made by Prof. Christian Reichardt and also to his generous and altruistic scientific help that he has always shown.

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Section: Introductionsupporting

confidence: 67%

The Photophysics of Diphenyl Polyenes Analyzed by Their Solvatochromism

Catalán,

Hopf

2024

Liquids

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“…In principle, one would attribute this change to an increase in the torsional movement of all-trans-DPH phenyl groups with increasing temperature. [38,41] Turek et al [16] in their work on the fluorescence of DPH in n-dodecane gave special importance to the fact that their results, see fig. 10 of their work, present a clear situation of mirror symmetry with respect to the corresponding absorption spectrum of the compounds, following the proposition formulated by Levshin.…”

Section: On the Causes That Allow Understanding The Different Proposa...mentioning

confidence: 99%

On the temperature‐dependent isomerization of all‐trans‐1,6‐diphenyl‐1,3,5‐hexatriene in solution: A reappraisal

Catalán

2022

J of Physical Organic Chem

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In this work, we present absorption, emission, and excitation of emission spectra of all‐trans‐DPH obtained in solution between 77 and 363 K. The analysis of these spectra allows to evaluate that this molecular probe, widely used in biophysics, does not isomerizes in solution to s‐cis‐DPH at the temperatures explored. These results are in contradiction to those reported by previous studies that emphasize that (a) all‐trans‐DPH isomerizes to s‐cis‐DPH when dissolved and the temperature ranges from 283 to 373 K and (b) the molar fraction of s‐cis‐conformer equals, or even exceeds, the molar fraction of the all‐trans‐conformer at the highest temperature studied. In this work, we show how we can infer the changes taking place in the molecular structure of DPH looking at the wavenumber (ν) shift of the peaks on the absorption and emission spectra as a function of temperature. The analysis of these band shifts allows us to corroborate the change, determined by Ogawa et al. by X‐ray diffraction, that occurs in the structure of DPH in the crystalline phase through a bicycle pedal process with temperature.

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“…In Fig. 2a we jointly show the bathochromic shift of ttbP4 solution in DECMCH (*) and of the crystalline form, 4tmC (•), when decreasing the temperature from 293 to 77 K. It is important to remark that the displacements found for ttbP4 are about half of those measured for diphenylpolyenes under identical conditions [32]. The smaller bathochromic shifts found for ttbP4 point to a more rigid planar structure compared to the corresponding diphenyl polyene.…”

Section: Photophysics Of 4tmcmentioning

confidence: 85%