3-[(8Z)-8-[(2E)-2-[[7-(2-carboxyethyl)-9-selena-7-azoniabicyclo[4.3.0]nona-1,3,5,7-tetraen-8-yl]methylidene]butylidene]-4-methyl-9-selena-7-azabicyclo[4.3.0]nona-2,4,10-trien-7-yl]propanoic acid bromi