Biphenyl‐Based Disc‐ vs. Rod‐Shaped Phenylacetylenes: Mesomorphism and Electronic Properties

Hennrich, Gunther; Ortíz, Pedro; Cavero, Emma; Hanes, Robert E.; Serrano, José Luís

doi:10.1002/ejoc.200800568

Cited by 13 publications

(5 citation statements)

References 39 publications

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“…With the exception of 2e whose fluorescence is efficiently quenched due to the presence of the nitro substituents, the triindoles are well fluorescent with compound 2a displaying an especially high fluorescence quantum yield of 0.81 in solution . The large Stokes shifts between 78 and 127 nm observed for all triindole derivatives are the consequence of both the nuclear reorganization taking place after irradiation and prior to emission as a result of electronic redistribution and the conformational changes in the biphenyl fragments (planarization) upon excitation …”

Section: Resultsmentioning

confidence: 99%

Self-Assembly of C₃-Symmetrical Hexaaryltriindoles Driven by Solvophobic and CH−π Interactions

et al. 2010

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The synthesis and aggregation properties of a series of differently substituted star-shaped hexaaryltriindoles both in solution and in the solid state are being reported. While these molecules do not show any significant intermolecular aggregation in CDCl(3), it has been possible to induce aggregation by increasing the polarity of the solvent and therefore facilitating the occurrence of solvophobic forces. A study of the influence of the electronic character of peripheral substituents on the self-association behavior in solution has shown that increasing the electron-donor character of the substituents facilitates self-association while derivatives substituted with electron-acceptor substituents do not self-assemble. The electronic nature of the substituents also has an influence in the geometry of the stacking of these derivatives observed in the solid state. While unsubstituted hexaphenyl triindole self-assemble in a staggered face-to-face arrangement, attaching six cyano functional groups results in an offset stacking. The influence of the substituents in the strength and geometry of the stacking tendency contrasts with the trend expected for an aggregation induced solely by pi-pi interactions, but can be explained considering an important contribution of multiple cooperative CH-pi interactions.

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Section: Resultsmentioning

confidence: 99%

Self-Assembly of C₃-Symmetrical Hexaaryltriindoles Driven by Solvophobic and CH−π Interactions

et al. 2010

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“…We attribute the distinct mesomorphism of 5 vs 6 to subtle differences in the dipole moments of both, which in consequence affects the alignment of the molecules in the bulk. On the molecular level, this variation stems from the less efficient π-conjugation in the biphenyl fragment of 5 …”

Section: Resultsmentioning

confidence: 99%

Chiral Biphenylacetylene Smectic Liquid Crystals

et al. 2010

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Standard Sonogashira coupling afforded rod-like, phenylacetylene extended biphenyl mesogens substituted with different chiral alkoxy chains, starting from commercially available 4-(4′-bromophenyl)phenol. Depending on the position of the chiral center and the polar nature of the target molecules as determined by the electron withdrawing end-groups, different types of smectic liquid crystals are formed. The liquid crystal phases are fully characterized by polarized optical microscopy, differential scanning calorimetry, and X-ray diffraction. In two cases, the molecular chirality is transferred to the supramolecular assembly, which is proved by circular dichroism measurements in the chiral mesophase.

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“…In this work we have studied molecules of the 4-X-4′-[(4′′-Y-phenyl)ethynyl]biphenyl homologous series, with the biphenyl fragment being a common structural motif for thermotropic calamitic liquid crystals (Scheme ).…”

Section: Introductionmentioning

confidence: 99%

Steric and Electronic Situation in the 4-X-4′-[(4′′-Y-Phenyl)ethynyl]biphenyl Homologous Series: A Joint Theoretical and Spectroscopic Study

Ortíz

Suardíaz²,

Vega³

et al. 2010

J. Phys. Chem. A

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In this work we have studied the rotational barriers, the polarization of the acetylenic triple bond, and the molecular dipole moments in the 4-X-4'-[(4''-Y-phenyl)ethynyl]biphenyl homologous series using the density functional theory (DFT) and 1D/2D NMR spectroscopy. This series of compounds constitutes an effective base for the acquisition of liquid crystals. The equilibrium angle (theta(eq)) and the torsional barriers DeltaE(0 degrees) and DeltaE(90 degrees) are not very sensitive to the substituent effects. We have found evidence for the similarity in the pi-conjugation of the Y-substituted and X,Y-disubstituted compounds, the latter with mesomorphic properties, by means of the graphic analysis of the relationship between the molecular dipolar moment mu(D) and the difference between the (13)C NMR chemical shifts of the acetylenic carbon atoms (Deltadelta(CI[triple bond]CII) [ppm]). The obtained results contribute to a better understanding of the structure-activity relationship for potential liquid crystalline systems.

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Biphenyl‐Based Disc‐ vs. Rod‐Shaped Phenylacetylenes: Mesomorphism and Electronic Properties

Cited by 13 publications

References 39 publications

Self-Assembly of C₃-Symmetrical Hexaaryltriindoles Driven by Solvophobic and CH−π Interactions

Self-Assembly of C₃-Symmetrical Hexaaryltriindoles Driven by Solvophobic and CH−π Interactions

Chiral Biphenylacetylene Smectic Liquid Crystals

Steric and Electronic Situation in the 4-X-4′-[(4′′-Y-Phenyl)ethynyl]biphenyl Homologous Series: A Joint Theoretical and Spectroscopic Study

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Biphenyl‐Based Disc‐ vs. Rod‐Shaped Phenylacetylenes: Mesomorphism and Electronic Properties

Cited by 13 publications

References 39 publications

Self-Assembly of C3-Symmetrical Hexaaryltriindoles Driven by Solvophobic and CH−π Interactions

Self-Assembly of C3-Symmetrical Hexaaryltriindoles Driven by Solvophobic and CH−π Interactions

Chiral Biphenylacetylene Smectic Liquid Crystals

Steric and Electronic Situation in the 4-X-4′-[(4′′-Y-Phenyl)ethynyl]biphenyl Homologous Series: A Joint Theoretical and Spectroscopic Study

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Self-Assembly of C₃-Symmetrical Hexaaryltriindoles Driven by Solvophobic and CH−π Interactions

Self-Assembly of C₃-Symmetrical Hexaaryltriindoles Driven by Solvophobic and CH−π Interactions