HRS method

Ary] 2-amino-5-(p-aminophenyl)thia2oles of the general formula 116 were prepared by condensing phenylthiosemicarbazides (115) with either w-bromoacetophenone by refluxing in alcohol for 2 hr (Method A) or with acetophenones and iodine on a steam bath for 8 hr (Method B) Scheme 53 (517), with R = para Me, MeO, Cl, Br, I, NOj, NHj, Ph ortho Me, NOjl or meta Br, I, NO. Yields ranged from 55 to 90% from Method A and 40 to 70% from Method B. 

An important goal of this study is to characterize the noncentrosymmetric arrangement of the azobenzene branches in dendrimers and the effect of these dendrimers on macroscopic second-order susceptibihty. The NLO activity of the dendrimers can be characterized by their molecular hyperpolarizabihty. The hyper-Rayleigh scattering (HRS) method is a reliable way of measuring the mol-... 

The hydrochlorides of 2-aminoglycoses were reacted with alkoxymethy-lenemalonate in the presence of sodium carbonate in water at ambient temperature (method A) or in the presence of triethylamine in boiling ethanol for 0.5 hr (method B) to give aminomethylenemalonates (40). Method A afforded higher yields (97-98%) than method B (55-94%) (84MI7 88MI4). 

N-Substituted aminomethylenemalonates (275) were obtained in 5-56% yields in the reactions of diethyl aminomethylenemalonate (13) and ketones or ketals in the presence of phosphorus pentoxide in THF at room temperature for 1-5 days (method A) or by heating in the presence of a small amount of p-toluenesulfonic acid in o-xylene for 15-22 hr (method... 

B) (75JHC1245). Methyl ethyl ketone and acetophenone did not react under these conditions. Under the conditions of method B, 2-methylcyclo-hexanone gave A7-(2-methylcyclohexen-l-yl)aminomethylenemalonate (276, R = Me) in 36% yield. Cyclohexanone diethyl ketal and diethyl aminomethylenemalonate (13) were reacted at 140°C for 35 hr (method... 

Tin vapor viscosities ol all l( jr compound were extt mated by (hr method of Reichcnhcrg a ... 

The hyperpolarizability coefficients of these model compounds, determined by the HRS method, are given in Table 10.3. 

For brevity, we will refer to this as the HR method. It is sometimes referred to as the ion-electron method. 

The molecular hyperpolarizability of charged ionic compounds was not directly accessible for measurement until the HRS method was reestablished [36]. Therefore only recently research has been focused on the effect of donor or acceptor substitution and elongation of the conjugation path length to demonstrate the engineering guidelines for enhancing molecular optical nonlinearities. 

In contrast to the EFISH method, the hyperpolarizability P can be measured directly by means of the HRS method developed by Clays and Persoons [21, 22]. This method involves measuring the intensity of the incoherently scattered, frequency-doubled light from isotropic solutions. As shown in Fig. 3.2, an infrared laser beam is focused on the center of a cell containing a solution of the NLO-active compound. 

Presenz U, Schmid S, Hartmann R, Luck HR. Method for producing a polyamide compound. US patent 6 881477, assigned to EMS-Chemie AG, Domat/Ems, CH 2005. 

A provisional breakdown of HR methods may be based on two fundamental criteria (Figure 1.2) the material delivery method and the heating method. 

On the other hand, the HRS method allows measurements on nonpolar and/or ionic molecules. In HRS experiments, the first hyperpolarizability is derived from the intensity of the scattered light at optical frequency 2a> on incidence of a laser pulse at co. Contrary to EFISHG, the HRS signal originates from incoherent fluctuations of individual molecular scatterers that do not exhibit specific phase relations with respect to the others. 

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