The use of (R)-(+)-alpha-methylbenzylamine and (S)-(-)-alpha-methylbenzylamine as chiral moieties to obtain monomers for second harmonic generation crystals

Abstract

The use of chiral moieties as a way to warranty noncentrosymmetric monomers crystals in order to obtain second harmonic generation materials has been the study purpose of nonlinear properties of the two new N-(R)-(+)-alpha- and N-(S)-(-)-alpha-methylbenzylmethacryloylamine enantiomeric monomers. The enantiomeric monomers crystallized in a monoclinic system and belong to the P2(1) space group and the asymmetric unit comprises two molecules of the enantiomeric compound. The molecular structure shows that the amide moiety is not coplanar with the double bond of the methylene group, as one would assume before hand. The hydrogen bond system is formed between the symmetry related molecules using H atom of the amide and keto oxygen of consecutive molecules along the a axis forming parallel series of continuous chains The second-harmonic generation produced 532 nm light for both compounds and they were measured following the Kurtz and Perry modified procedure in powder form. The values were compared with the chiral compound (saccharose, sucrose, know as sugar) calibration spectrum used as standard. The monomers characterization were made using conventional methods: melting point measurements, infrared spectroscopy, nuclear magnetic resonance spectroscopy and polarimetry. (C) 2003 Elsevier Science B.V. All rights reserved.