I am busy doing a project with my Honours student, Rachel Mey, and Ivan Bernal (Texas, USA) on the much-studied NaClO3 and NaBrO3 crystals. NaClO3 and NaBrO3 are isomorphous, cubic crystals in the space group P213. We have confirmed that crystals of NaClO3 and NaBrO3 that have the same absolute configuration, but rotate polarized light in opposite directions. I have searched the CSD and ICSD for other examples, but cannot find any. Any suggestions would help. Demi Levendis ([email protected])