Investigation On The Growth And Optical Activity Of Sodium Halogen Crystals

The investigation of the optical activity of the chiral crystal can not only help human learn the origin of life, but also has important significance on human's health and the development of new functional materials. In this thesis, NaClO₃ and NaCl_1-xBr_xO₃ crystals were grown from aqueous solution with lowering the temperature. Crystallization of NaClO₃ on chiral symmetry breaking through temperature recycling process was investigated. The growth habits and optical activity of NaCl_1-xBr_xO₃ crystal were studied through the different content of Br element doping in NaClO₃, and the optical rotatory ratio of NaClO₃, NaBrO₃ and NaCl_1-xBr_xO₃ crystals were measured. The main research results are summarized briefly as follows:1. Well crystallized NaClO₃ crystal with size up to 55mm*55mm*55mrn was obtained successfully from aqueous solution by lowering the temperature.2. With a constant stirring, the influence of the temperature on the chiral symmetry breaking of NaClO₃ crystal was studied by 10 times temperature recycling processes. The results of the experiment showed that mean crystal enantiomeric excess increased from 0.81 to 0.97 with the variety of cycle times from 1 to 10, and at the same time, the cee distribution range of ten crystallizations of every group changed obviously from broad (0.47-1) to narrow (0.92-1). An analysis of the data indicated that the "up-down" temperature recycling played a very important role in chiral symmetry breaking during crystallization of NaClO₃ crystal. A theory analysis for these results was given.3. The different content of Br element doping in NaClO₃ made the growth habits of NaCl_1-xBr_xO₃ crystals change. With the increase of the concentration of Br element doping in NaC103, the beginning growth of the seed crystal was delayed, the defects would like to appear easily in the crystals and the transparent of the crystal was deteriorated. At the same time, the doping Br element destroyed the chirality of NaClO₃ crystal and formed NaCl_1-xBr_xO₃ crystals. The NaCl_1-xBr_xO₃ crystals have also the optical activity and chiralityat local area, but for the whole NaCl_1-xBr_xO-3 crystals, the chirality was destroyed. The optical rotatory ratio of NaClO₃, NaBrO₃ and (NaCl_1-xBr_xO₃)_0.02 were measured by the equipment built by ourselves. The results showed that the optical rotatory ratio of NaClO₃, NaBrO₃ accorded with the theory calculation value very well, but for the(NaCl_1-xBr-xO₃)_0.02 crystal, we could not get the light extinction point on the light baffle all along, so the optical rotatory ratio of (NaCl_1-xBr_xO₃)_0.02 crystal was not obtained.