TY - JOUR
T1 - Remarkable NLO response and infrared absorption in simple twisted molecular π-chromophores
AU - Albert, I. D L
AU - Marks, Tobin J
AU - Rather, M. A.
PY - 1998/11/4
Y1 - 1998/11/4
N2 - Computational modeling reveals that, by substitutional modification of interplanar dihedral angles in a series of quinopyrans, both the optical absorption cross section and the first hyperpolarizability can be widely tuned in both frequency and magnitude. This is a promising structural control scheme for modulating molecular nonlinear optical and infrared absorption properties. The maximum nonresonant μβ estimated for a tetraalkyl- substituted 4-quinopyran, the full AM1-optimized interplanar dihedral angle of which is 104°, is ~70000 x 10-48 esu, at an excitation energy of 0.10 eV. This is 4 orders of magnitude larger than that of the archetypical NLO chromophore, 4-N,N'-(dimethylamino)-4'-nitrostilbene, at the same excitation frequency. The effects of conjugation pathway, strength of the electron donor/acceptor groups, and auxiliary donor and acceptor on the molecular response properties have also been analyzed. The optical absorption at a twist angle of 90% when the molecule can be described as two disjoint π- subfragments, exhibits characteristic absorptions from the individual subfragments and also inter-subfragment excitation; the former occur at high energies and with high oscillator strengths, while the latter occurs at low energy and with low oscillator strength.
AB - Computational modeling reveals that, by substitutional modification of interplanar dihedral angles in a series of quinopyrans, both the optical absorption cross section and the first hyperpolarizability can be widely tuned in both frequency and magnitude. This is a promising structural control scheme for modulating molecular nonlinear optical and infrared absorption properties. The maximum nonresonant μβ estimated for a tetraalkyl- substituted 4-quinopyran, the full AM1-optimized interplanar dihedral angle of which is 104°, is ~70000 x 10-48 esu, at an excitation energy of 0.10 eV. This is 4 orders of magnitude larger than that of the archetypical NLO chromophore, 4-N,N'-(dimethylamino)-4'-nitrostilbene, at the same excitation frequency. The effects of conjugation pathway, strength of the electron donor/acceptor groups, and auxiliary donor and acceptor on the molecular response properties have also been analyzed. The optical absorption at a twist angle of 90% when the molecule can be described as two disjoint π- subfragments, exhibits characteristic absorptions from the individual subfragments and also inter-subfragment excitation; the former occur at high energies and with high oscillator strengths, while the latter occurs at low energy and with low oscillator strength.
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U2 - 10.1021/ja982073c
DO - 10.1021/ja982073c
M3 - Article
AN - SCOPUS:0032483727
VL - 120
SP - 11174
EP - 11181
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 43
ER -