Ionic octupolar

Ray and Leszcynski172 have investigated the hyperpolarizabilities of ionic octupolar compounds including solvent effects and Ray173 has also analysed the molecular structure and [1 hyperpolarizabilities of a series of ionic organic and organometallic compounds. 

Keywords Nonlinear optical materials Ionic octupolar Zwitterionic Ab initio Stilbazolium ... 

Ray reviews some recent developments concerning the design of novel materials with large NLO effects. He considers a series of organic salts and various organometallic derivatives where it was found that metal-to-ligand charge-transfer has a dominant contribution to the second-order NLO response. He also discusses the first hyperpolarizability of several retinal derivatives, ionic octupolar molecules and zwitterionic derivativatives. Solvent effects on NLO properties are also reviewed. 

Due to their ionic interaction, they conquer the dipole attraction and in fact, ionic dipolar compounds exhibit excellent bulk SHG efficiency [7-10]. Dynamic hyperpolarizabiUties of 1,3,5 substituted benzenes and triazines cations calculated by ZINDO/CV/SCRF method are listed in Table 6. Experimental data [92] for the corresponding neutral octupolar molecules (as shown in Figure 15) are also listed in Table 6. 

Figure 14. Structure of ionic extended conjugated octupolar compounds used in this investigation.

EFISH has usually been used to evaluate nonlinearities of neutral organometallic complexes, the presence of ionic species rendering it difficult to apply high electric fields to a solution. It is also not possible to utilize EFISH when the complex has no net dipole, and so the method is not useful for molecules of trigonal symmetry, for example, although they can have a strong second-order nonlinearity of octupolar type (i.e. leading to a non-zero septor part of P) with a zero dipolar (vector) part of P... 

---