Non-linear optical properties of organic molecules. Part 2. Effect of conjugation length and molecular volume on the calculated hyperpolarisabilities of polyphenyls and polyenes

Morley, John; Docherty, Vincent J.; Pugh, D.

doi:10.1039/p29870001351

Cited by 123 publications

(55 citation statements)

References 2 publications

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“…The polyenal molecule is calculated to present a p, value, which is over two times larger than in paranitroaniline (16.9 vs. 7.9 x esu [31]). This fully illustrates the better efficiency of polyenes over phenylenes in terms of second-order polarizabilities, a feature which by now is well documented [8,9,32,33].…”

Section: First-order and Second-order Polarizabilitiesmentioning

confidence: 64%

Electronic structure and nonlinear optical properties of push–pull conjugated molecules

Meyers

Brédas

1992

Int J of Quantum Chemistry

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We present a review of ab initio calculations we recently performed on organic molecules presenting promising quadratic nonlinear optical properties. These molecules constitute so-called push-pull conjugated compounds in which a conjugated segment is capped at one end by an acceptor group and at the other end by a donor group. We focus on three series of systems: (i)pamino-p'4trodiphenylacetylenes for which "unusual" distorsion patterns have been recently reported; (ii) benzodithiapolyenals, which present among the largest second-order polarizabilities ever measured; and (iii) 2-methylene-2H-pyrrole derivatives. Our results are found to provide a detailed understanding of the available experimental data.

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Section: First-order and Second-order Polarizabilitiesmentioning

confidence: 64%

Electronic structure and nonlinear optical properties of push–pull conjugated molecules

Meyers

Brédas

1992

Int J of Quantum Chemistry

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“…Since the vast majority of molecules that have been explored for their NLO response have dominantly aromatic ground states that resist CT polarization (1), they likely exhibit relatively little charge separation and little change in geometry when comparing their gas-phase and solution structures. Thus, for these systems, gas-phase computations of geometry and optical properties including hyperpolarizabilities often agree reasonably weli with those measured in solution (12,14). Ignoring the medium dependence of the chemical structure of merocyanines, however, will tend to underestimate the CT contribution to their ground-state wave function in most solvents (6) leading to calculated hyperpolarizabilities that can differ significantly with those measured in solution (15).…”

mentioning

confidence: 71%

“…1 b and c) are sensitive to the dielectric properties of the surrounding medium. Although solvatochromic behavior is usually interpreted solely as a change in the electronic distribution at a fixed nuclear geometry (4), for merocyanines it has been shown that the molecular geometry also undergoes significant changes as well (5)(6)(7)(8)(9)(10)(11) 11298 Chemistry: Gorman and Marder Many computational studies of molecular hyperpolarizability using either the sum-over-states (12) or finite-field (13) methods employ computed molecular geometries. In these cases, the geometry is explicitly being computed for a molecule in the gas phase.…”

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confidence: 99%

An investigation of the interrelationships between linear and nonlinear polarizabilities and bond-length alternation in conjugated organic molecules.

Gorman

Marder

1993

Proc. Natl. Acad. Sci. U.S.A.

237

148

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A computational method was devised to explore the relationship of charge separation, geometry, molecular dipole moment (p), polarizability (a), and hyperpolarizabilities (,B, y) in conjugated organic molecules. We show that bond-length alternation (the average difference in length between single and double bonds in the molecule) is a key structurally observable parameter that can be correlated with hyperpolarizabilities and is thus relevant to the optimization of molecules and materials. By using this method, the relationship of bond-length alternation, it, a, 3, and y for linear conjugated molecules is ilustrated, and those molecules with maximized a, 3, and y are described. The first coefficient, a, is the linear polarizability and is related to the first derivative of the dipole moment with respect to E. The higher-order terms (3 and y are referred to as the first and second hyperpolarizabilities. The polarization associated with these higher-order coefficients is responsible for second-and third-order NLO effects. In this paper, we discuss a computational method that predicts structural features ofmolecules that have maximized a, B, and 'yfor a given molecular length. Throughout, we will emphasize what we believe to be a key experimentally accessible structural parameter, bond-length alternation, and illustrate the correlation between it and the NLO response.Prototypical organic chromophores for second-order nonlinear optics contain a polarizable r-electron system and donor and acceptor groups to create an asymmetric polarizability in the molecule. It has been recently hypothesized that there is an optimal combination of donor/acceptor strengths that will maximize 8 (1 (Fig. la). Thus, the aromatic ground state impedes electronic polarization in an applied field and effectively reduces the donor and acceptor strengths of a given pair connected by an aromatic bridge. The visible absorption maximum and extinction coefficients of merocyanines ( Fig. 1 b and c) are sensitive to the dielectric properties of the surrounding medium. Although solvatochromic behavior is usually interpreted solely as a change in the electronic distribution at a fixed nuclear geometry (4), for merocyanines it has been shown that the molecular geometry also undergoes significant changes as well (5)(6)(7)(8)(9)(10)(11)

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“…[1][2][3][4] First and second hyperpolarizabilities can be observed with molecules that possess electron donor and acceptor groups connected by a conjugated p-electron bridge that allows the possibility of intramolecular charge transfer. [5][6][7][8] The non-linear optical properties are usually enhanced by one of the following modifications: (a) increasing the donor group releasing ability; (b) increasing the accepting ability of the acceptor group; (c) lengthening the conjugated system. Although increasing the conjugated system causes a pronounced bathochromic shift, it results in a remarkable decrease in the solubility of the dye in common organic solvents.…”

Section: Introductionmentioning

confidence: 99%

Organometallic dyes: Part 1. Synthesis of orange to cyan dyes based on donor–conjugated–acceptor chromogenes using ferrocene as the donor group

Asiri¹

2001

Applied Organom Chemis

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A novel series of organometallic donor-conjugated-acceptor dyes derived from ferrocene as the donor group have been synthesized via the Knoevenagel reaction of ferrocene carboxaldehyde and various active methylene compounds to give a range of dyes ranging from orange to blue-green in color. The most bathochromic dye is that derived from dialkyl thiobarbituric acid and the least is that derived from the tetralone. The dyes showed an unusual negative solvatochromism as the solvent polarity increased. All dyes synthesized are expected to have some non-linear optical properties, as evidenced from the pronounced solvatochromism.

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Non-linear optical properties of organic molecules. Part 2. Effect of conjugation length and molecular volume on the calculated hyperpolarisabilities of polyphenyls and polyenes

Cited by 123 publications

References 2 publications

Electronic structure and nonlinear optical properties of push–pull conjugated molecules

Electronic structure and nonlinear optical properties of push–pull conjugated molecules

An investigation of the interrelationships between linear and nonlinear polarizabilities and bond-length alternation in conjugated organic molecules.

Organometallic dyes: Part 1. Synthesis of orange to cyan dyes based on donor–conjugated–acceptor chromogenes using ferrocene as the donor group

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