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

TY - JOUR

T1 - Steric and Electronic Situation in the 4-X-4′-[(4′′-Y-Phenyl)ethynyl]biphenyl Homologous Series

T2 - A Joint Theoretical and Spectroscopic Study

AU - Ortiz, Pedro D.

AU - Suardíaz, Reynier

AU - de Vega, Laura

AU - Hennrich, Gunther

AU - Ortiz, Pedro J.

PY - 2010

Y1 - 2010

N2 - 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 (θeq) and the torsional barriers ΔE(0°) and ΔE(90°) are not very sensitive to the substituent effects. We have found evidence for the similarity in the π-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 μ(D) and the difference between the 13C NMR chemical shifts of the acetylenic carbon atoms (ΔδCI≡CII [ppm]). The obtained results contribute to a better understanding of the structure−activity relationship for potential liquid crystalline systems.

AB - 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 (θeq) and the torsional barriers ΔE(0°) and ΔE(90°) are not very sensitive to the substituent effects. We have found evidence for the similarity in the π-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 μ(D) and the difference between the 13C NMR chemical shifts of the acetylenic carbon atoms (ΔδCI≡CII [ppm]). The obtained results contribute to a better understanding of the structure−activity relationship for potential liquid crystalline systems.

U2 - 10.1021/jp911163t

DO - 10.1021/jp911163t

M3 - Article

SN - 1089-5639

VL - 114

SP - 2939

EP - 2944

JO - JOURNAL OF PHYSICAL CHEMISTRY A

JF - JOURNAL OF PHYSICAL CHEMISTRY A

IS - 8

ER -