Molecular Design Parameters of Anthraquinone Dyes for Guest-Host Liquid-Crystal Applications: Experimental and Computational Studies of Spectroscopy, Structure and Stability

TY - JOUR

T1 - Molecular Design Parameters of Anthraquinone Dyes for Guest-Host Liquid-Crystal Applications

T2 - Experimental and Computational Studies of Spectroscopy, Structure and Stability

AU - Sims, Mark Timothy

AU - Abbott, Laurence Colin

AU - Cowling, Stephen James

AU - Goodby, John William

AU - Moore, John N

N1 - © 2016 American Chemical Society

PY - 2016/5/26

Y1 - 2016/5/26

N2 - A set of five anthraquinone dyes with bis(4-propylphenyl) substituent groups, connected via sulfide or amine linkages at the 1,5-positions or directly at the 2,6-positions, have been studied in solution by UV-vis spectroscopy and electrochemistry, allied with density functional theory calculations of structures, electronic transitions, and redox potentials. The visible transitions and redox potentials are shown to vary with the HOMO and LUMO energies, with the variation in both color and redox stability between the dyes being attributable principally to variations in the HOMOs located mainly on the substituents and outer anthraquinone rings. The calculated molecular structures and visible transition dipole moments are shown to vary subtly with substituent, giving variations in the molecular aspect ratios, minimum moment of inertia axes, and transition dipole moment vector orientations that can rationalize the alignment trends reported in the literature for such anthraquinone dyes in liquid crystal hosts, showing why 1,5-disulfide and 2,6-diphenyl substituents give better designs than 1,5-diamine substituents. The computational approaches reported here are shown to give good matches with experimental trends, indicating that they may be used more generally to aid the rational molecular design of dyes for applications as guests in liquid crystal hosts.

AB - A set of five anthraquinone dyes with bis(4-propylphenyl) substituent groups, connected via sulfide or amine linkages at the 1,5-positions or directly at the 2,6-positions, have been studied in solution by UV-vis spectroscopy and electrochemistry, allied with density functional theory calculations of structures, electronic transitions, and redox potentials. The visible transitions and redox potentials are shown to vary with the HOMO and LUMO energies, with the variation in both color and redox stability between the dyes being attributable principally to variations in the HOMOs located mainly on the substituents and outer anthraquinone rings. The calculated molecular structures and visible transition dipole moments are shown to vary subtly with substituent, giving variations in the molecular aspect ratios, minimum moment of inertia axes, and transition dipole moment vector orientations that can rationalize the alignment trends reported in the literature for such anthraquinone dyes in liquid crystal hosts, showing why 1,5-disulfide and 2,6-diphenyl substituents give better designs than 1,5-diamine substituents. The computational approaches reported here are shown to give good matches with experimental trends, indicating that they may be used more generally to aid the rational molecular design of dyes for applications as guests in liquid crystal hosts.

UR - http://www.scopus.com/inward/record.url?scp=84973124556&partnerID=8YFLogxK

U2 - 10.1021/acs.jpcc.6b03607

DO - 10.1021/acs.jpcc.6b03607

M3 - Article

SN - 1932-7447

VL - 120

SP - 11151

EP - 11162

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

IS - 20

ER -