Nonlinear optical compounds

Otsuka, H. Shinkai, S. J. Am. Chem. Soc. 1996, 118, 755. A similar example using a calix[4]resorcarene is reported by Inouye, I. Hashimoto, K. Isagawa, 

6]arenes has also been reported, with X-ray structures, by Lehn, J.-M. Meric, R. Vigneron, J.-P. Cesario, M. Guilhem, J. Pascard, C. Asfari, Z. Supramol. Chem. 1995, 5, 97. 

For an evaluation of optical nonlinearities in calixarenes, see Morley, J. O. Naji, M. J. Phys. Chem. A 1997,101,2681. 

Bohmer, V. Kramer, P. Vogt, W. Wortmann, R. Supramol. Chein. 1993, 2, 65. 

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Antipin, M. Y, Timofeeva, T. V., Clark, R. D., Nesterov, V. N., Dolgushin, F. M., Wu, J. and Leyderman, A. (2001). Crystal structures and molecular mechanics calculation of nonlinear optical compounds 2-cyclooctylamino-5-nitropyridine (COANP) and 2-adamantylamino-5-nitropyridine (AANP). New Polymorphic modifcation of AANP and electrooptic effects. /. Mater. Chem., 11, 351-8. [213] Apperley, D. C., Fletton, R. A., Harris, R. K., Lancaster, R. W., Tavener, S. and Threlfall, T. L. (1999). Sulfathiazole polymorphism studied by magic-angle spinning NMR. / Pharm. ScL, 88, 1275-80. [135,139f]... 

Nakatsu, K., Yoshie, N., Yoshioka, H., Nogami, T., Shirota, Y, Shimizu, Y, Uemiya, T. and Yasuda, N. (1990). Polymorphism and the molecular and crystal structures of a 2nd-order nonlinear optical-compound containing a 1,3-dithiole ring. Mol. Cryst. Liq. Cryst., 182, 59-69. [213]... 

Nitroaniline is the standard of comparison for nonlinear optical compounds. The molecule is noncentrosymmetric on the molecular level and has a high hyperpolarizability (P = 34.5 x 10" esu, Oudar and Chemla, 1977), but it crystallizes centrosymmetrically therefore, it does not show second-order nonlinear optical effects in the crystalline phase (Miyata et al., 1994). In contrast, 3-nitroaniline crystallizes in a noncentrosymmetric space group, but the P value is much lower (P = 6.0 X esu, Oudar and Chanla, 1977) than the value of 4-nitroaniline, because the charge transfer in the latter case (para-isomer) is much stronger. 

Clays and Persoons presented a new technique in 1992 for the determination of the hyperpolarizabilities of nonlinear optical compounds in solution using the hyper-Rayleigh scattering (HRS). The values for first hyperpolarizabilities can be obtained from second-order scattered light intensity. This method has several advantages over the EFISH technique it needs no electric field, and thus the experiment is simplified, the hyperpolarizability P can be directly measured, and the P values for salts can be determined as weU. 

At this point not many nonlinear optical compounds based on boron clusters as electron donors and acceptors, respectively, have been described in the literature. A few examples limited to carborane and dodecaborate derivatives are now introduced. 

The applications of this simple measure of surface adsorbate coverage have been quite widespread and diverse. It has been possible, for example, to measure adsorption isothemis in many systems. From these measurements, one may obtain important infomiation such as the adsorption free energy, A G° = -RTln(K ) [21]. One can also monitor tire kinetics of adsorption and desorption to obtain rates. In conjunction with temperature-dependent data, one may frirther infer activation energies and pre-exponential factors [73, 74]. Knowledge of such kinetic parameters is useful for teclmological applications, such as semiconductor growth and synthesis of chemical compounds [75]. Second-order nonlinear optics may also play a role in the investigation of physical kinetics, such as the rates and mechanisms of transport processes across interfaces [76]. 

Most of the envisioned practical applications for nonlinear optical materials would require solid materials. Unfortunately, only gas-phase calculations have been developed to a reliable level. Most often, the relationship between gas-phase and condensed-phase behavior for a particular class of compounds is determined experimentally. Theoretical calculations for the gas phase are then scaled accordingly. 

Enclosure also changes the redox properties of a compound, its color, and other physical properties (1,2). On this basis nonlinear optical materials, luminescence markers, controlled light switches, and other high-tech devices might be designed and prepared (15,17,137). 

The cadmium chalcogenide semiconductors (qv) have found numerous appHcations ranging from rectifiers to photoconductive detectors in smoke alarms. Many Cd compounds, eg, sulfide, tungstate, selenide, teUuride, and oxide, are used as phosphors in luminescent screens and scintiUation counters. Glass colored with cadmium sulfoselenides is used as a color filter in spectroscopy and has recently attracted attention as a third-order, nonlinear optical switching material (see Nonlinear optical materials). DiaLkylcadmium compounds are polymerization catalysts for production of poly(vinyl chloride) (PVC), poly(vinyl acetate) (PVA), and poly(methyl methacrylate) (PMMA). Mixed with TiCl, they catalyze the polymerization of ethylene and propylene. 

The UV absorption spectra of most alkynylpyrazoles are quite similar to those of the corresponding pyrazoles. In general, they show a shift toward the visible [see (76T1293 98JCS(P1)3233)]. The UV spectra and nonlinear optical properties have been reported for 4-(4-methoxyphenylethynyl)-l-(4-nitrophenyl)-l/7-pyrazole and related compounds (94MI29). 

The semiconducting properties of the compounds of the SbSI type (see Table XXVIII) were predicted by Mooser and Pearson in 1958 228). They were first confirmed for SbSI, for which photoconductivity was found in 1960 243). The breakthrough was the observation of fer-roelectricity in this material 117) and other SbSI type compounds 244 see Table XXIX), in addition to phase transitions 184), nonlinear optical behavior 156), piezoelectric behavior 44), and electromechanical 183) and other properties. These photoconductors exhibit abnormally large temperature-coefficients for their band gaps they are strongly piezoelectric. Some are ferroelectric (see Table XXIX). They have anomalous electrooptic and optomechanical properties, namely, elongation or contraction under illumination. As already mentioned, these fields cannot be treated in any detail in this review for those interested in ferroelectricity, review articles 224, 352) are mentioned. The heat capacity of SbSI has been measured from - 180 to -l- 40°C and, from these data, the excess entropy of the ferro-paraelectric transition... 

The physical properties of the expanded radialenes were greatly enhanced upon donor functionalization, leading to the stable derivatives 76-78 with fully planar conjugated rr-chromophores [110]. These compounds exhibit large third-order nonlinear optical coefficients, can be reversibly reduced or oxidized, and... 

Fig. 8. Examples of some of the donor-acceptor substituted TEEs prepared for the exploration of structure-property relationships in the second- and third-order nonlinear optical effects of fully two-dimensionally-conjugated chromophores. For all compounds, the second hyperpolarizability y [10 esu], measured by third harmonic generation experiments in CHCI3 solution at a laser frequency of either A = 1.9 or 2.1 (second value if shown) pm is given in parentheses. n.o. not obtained...

Acentricity greatly enhances the y-value (see 92 vs 91 and 90 or 101 vs 99 and 100, Fig. 8). Such a trend had been predicted for certain ranges of compounds by theory [137] however when the first hyperpolarizability, which determines second-order nonlinear optical properties, is maximized, y is predicted to be zero [138]. 

If the electric dipole contribution dominates in the total SH response, the macroscopic response can be related to the presence of optically nonlinear active compounds at the interface. In this case, the susceptibility tensor is the sum of the contribution of each single molecule, all of them coherently radiating. For a collection of compounds, it yields ... 

In order to describe the problems of the nonlinear optical response from biological systems, the question of chirality must be addressed. Linear circular dichroism (CD) has been investigated extensively for biological compounds and a wealth of data are available on... 

Some quinones, having the ability to form intra- and/or intermolecular hydrogen bonds, exhibit high molecular hyperpolarizability and are third-order nonlinear optical (NLO) materials. Compound 39 has a %(3) of 5 x 10 11 esu at 1.9 pm, and is a third-order NLO material.23 The optoelectric properties of quinoid compounds correlate with their structures in crystals or on thin films.23... 

Tichonov EA, Shpak MT (1979) Nonlinear optical phenomena in organic compounds. Naukova Dumka, Kijiv (in Rus)... 

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