Solvent Effects on the Molecular Quadratic Hyperpolarizabilites

Albert, I. D. L.; Bella, Santo Di; Kanis, David R.; Marks, T. J.; Ratner, Mark A.

doi:10.1021/bk-1995-0601.ch004

Cited by 9 publications

(8 citation statements)

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“…Quantum-Chemical Calculations. There is a growing interest in applying computational techniques which in some way account for solute environment. ,− The COSMO continuum dielectric model, for example, calculates reaction fields using solvent dielectric constant, ε s , and solute radii as parameters. Studies on a series of conventional D−π−A molecules assuming solvation in DMSO (ε s = 45) show that modest increases in dipole moment can be expected.…”

Section: Solid State Structurementioning

confidence: 99%

Highly Dipolar, Optically Nonlinear Adducts of Tetracyano-p-quinodimethane: Synthesis, Physical Characterization, and Theoretical Aspects

et al. 1997

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A new series of nonlinear optical molecules are described where the ground state polarization is predominantly zwitterionic when the molecules are dissolved in solution. The molecules, which are derived in general from facile reactions between tertiary amines and tetracyano-p-quinodimethane (TCNQ), are of a type where the stabilization of the charge-separated ground state is favored by an increase in aromaticity over the neutral, quinoidal forms of the molecules. The measured second-order optical nonlinearity of one in the series has been measured by hyper-Rayleigh scattering and a figure of merit value, µβ(0), being the product of the dipole moment and static first hyperpolarizability, is found to be 9500 × 10 -48 esu. This value, which is higher than most other reported values, is taken from studies in chlorinated solvents of relatively low polarity, but the discussion emphasizes the evolution of µβ(0) with solvent polarity, showing that even higher values could be expected with only modest increases in the polarity of the surrounding medium. The analysis of experimental data taken during dipole moment studies is thoroughly examined, and it is concluded that full account must be taken of the molecular shape to correlate the results with theoretical calculations. An ellipsoidal reaction field model is preferred for these highly one-dimensional molecules having strongly anisotropic polarizabilities.

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Section: Solid State Structurementioning

confidence: 99%

Highly Dipolar, Optically Nonlinear Adducts of Tetracyano-p-quinodimethane: Synthesis, Physical Characterization, and Theoretical Aspects

et al. 1997

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“…The past decade has witnessed refinement of theoretical calculations and translation of theoretical results to structure-function relationships that can be utilized by organic chemists to guide the synthesis of new chromophores (5)(6)(7). In Table 1, we summarize representative chromophores derivative from this activity (8)(9)(10)(11).…”

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confidence: 99%

The role of London forces in defining noncentrosymmetric order of high dipole moment–high hyperpolarizability chromophores in electrically poled polymeric thin films

Dalton

Harper

Robinson

1997

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

203

161

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Graphs of second harmonic generation coefficients and electro-optic coefficients (measured by ellipsometry, attenuated total ref lection, and two-slit interference modulation) as a function of chromophore number density (chromophore loading) are experimentally observed to exhibit maxima for polymers containing chromophores characterized by large dipole moments and polarizabilities. Modified London theory is used to demonstrated that this behavior can be attributed to the competition of chromophore-applied electric field and chromophore-chromophore electrostatic interactions. The comparison of theoretical and experimental data explains why the promise of exceptional macroscopic secondorder optical nonlinearity predicted for organic materials has not been realized and suggests routes for circumventing current limitations to large optical nonlinearity. The results also suggest extensions of measurement and theoretical methods to achieve an improved understanding of intermolecular interactions in condensed phase materials including materials prepared by sequential synthesis and block copolymer methods.Nearly two decades ago, considerable excitement was generated by the theoretical prediction of large molecular hyperpolarizabilities for organic materials with extended -electron systems (1-4). The past decade has witnessed refinement of theoretical calculations and translation of theoretical results to structure-function relationships that can be utilized by organic chemists to guide the synthesis of new chromophores (5-7). In Table 1, we summarize representative chromophores derivative from this activity (8-11). If these chromophores could be incorporated into perfectly ordered noncentrosymmetric lattices, electro-optic coefficients of many hundreds of picometers per volt could be anticipated. Materials exhibiting such large macroscopic optical nonlinearity would, in turn, have a dramatic effect on communication and electromagnetic field sensing technologies (11).Such optical nonlinearities (hence, noncentrosymmetric order) have not yet been achieved. Efforts to obtain organic crystals exhibiting large electro-optic coefficients and which can be used to fabricate devices have largely proven unsuccessful (11). Very few crystal groups reflect noncentrosymmetric symmetry, and the small number that do are rarely assumed by organic chromophores. Moreover, when such organic crystals are realized (12), they are typically characterized by large growth anisotropy, making them unsuitable for device applications (11). Difficulty in obtaining suitable organic crystals has motivated attempts to fabricate noncentrosymmetric chromophore lattices by vapor phase deposition (or molecular beam epitaxy) methods (11,13,14), by Merrifield-type synthetic approaches (11,13,15,16), by LangmuirBlodgett film fabrication methods (13,17), by block copolymer approaches (11), and by electric field and laser-assisted poling methods (11,13). Of these methods, electric field poling is the protocol most easily applied to a wide range of chromo...

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“…Enormous progress has been made in the preparation, measurement, and mechanistic understanding of molecular chromophores. [59,70,71] Essentially, molecular chromophores can be idealized by increasing the oscillator strength, and change in dipole moment between ground and excited state. This model leads to qualitative correspondence between calculated and measured hyperpolarizibilities.…”

Section: Nonlinear Optical Materialsmentioning

confidence: 99%

“…This model leads to qualitative correspondence between calculated and measured hyperpolarizibilities. [70] More detailed semiempirical electronic structure calculations not only result in excellent agreement with experiment, but also can correct for solvation and environment effects using the self-consistent reaction field model, [71] and can suggest particular molecular structure motifs to increase the nonlinear response. [72] Methods for assembling and aligning these chromophores will be discussed in the next section.…”

Section: Nonlinear Optical Materialsmentioning

confidence: 99%

From Molecules to Materials: Current Trends and Future Directions

et al. 1998

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The development, characterization, and exploitation of novel materials based on the assembly of molecular components is an exceptionally active and rapidly expanding field. For this reason, the topic of molecule-based materials (MBMs) was chosen as the subject of a workshop sponsored by the Chemical Sciences Division of the United States Department of Energy. The purpose of the workshop was to review and discuss the diverse research trajectories in the field from a chemical perspective, and to focus on the critical elements that are likely to be essential for rapid progress. The MBMs discussed encompass a diverse set of compositions and structures, including clusters, supramolecular assemblies, and assemblies incorporating biomolecule-based components. A full range of potentially interesting materials properties, including electronic, magnetic, optical, structural, mechanical, and chemical characteristics were considered. Key themes of the workshop included synthesis of novel components, structural control, characterization of structure and properties, and the development of underlying principles and models. MBMs, defined as ªuseful substances prepared from molecules or molecular ions that maintain aspects of the parent molecular frameworkº are of special significance because of the capacity for diversity in composition, structure, and properties, both chemical and physical. Key attributes are the ability in MBMs to access the additional dimension of multiple length scales and available structural complexity via organic chemistry synthetic methodologies and the innovative assembly of such diverse components. The interaction among the assembled components can thus lead to unique behavior. A consequence of the complexity is the need for a multiplicity of both existing and new tools for materials synthesis, assembly, characterization, and theoretical analysis. For some technologically useful properties, e.g., ferro-or ferrimagnetism and superconductivity, the property is not a property of a molecule or ion; it is a cooperative solid-state (bulk) propertyÐa property of the entire solid. Hence, the desired properties are a consequence of the interactions between the molecules or ions, and understanding the solidstate structure as well as methods to predict, control, and modulate the structure are essential to understanding and manipulating such behaviors. As challenging as this is, molecules enable a substantially greater ability of control than atoms as building blocks for new materials and thus are well positioned to contribute significantly to new materials. The diversity of components and processes leads to the recognition of the critical role of cross-disciplinary research, including not only that between traditionally different areas within chemistry, but also between chemistry and biochemistry, physics, and a number of engineering disciplines. Enhancing communication and active collaboration between these groups was seen as a critical goal for the research area.

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Solvent Effects on the Molecular Quadratic Hyperpolarizabilites

Cited by 9 publications

References 0 publications

Highly Dipolar, Optically Nonlinear Adducts of Tetracyano-p-quinodimethane: Synthesis, Physical Characterization, and Theoretical Aspects

Highly Dipolar, Optically Nonlinear Adducts of Tetracyano-p-quinodimethane: Synthesis, Physical Characterization, and Theoretical Aspects

The role of London forces in defining noncentrosymmetric order of high dipole moment–high hyperpolarizability chromophores in electrically poled polymeric thin films

From Molecules to Materials: Current Trends and Future Directions

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