2,3-Dihydro-1,4-dithiino[2,3-c]furan-5,7-dione (5,6-dihydro-1,4-dithiin-2,3-dicarboxylic anhydride, dhca, 3,6-Dithia-3,4,5,6-tetrahydrophthalic anhydride) may be used in the synthesis of the following:photoluminescent three-dimensional (3-D) AgI coordination polymer5,6-dihydro-1,4- dithiin-2,3-dicarboxylateCuIIand MnIIcoordination complexes with 5,6-dihydro-1,4-dithiin-2,3-dicarboxylate as a primary building block2-heteroaryl-4,7-dithia-4,5,6,7-tetrahydro-1,3-indandiones3-arylmethylene-4,7-dithia-4,5,6,7-tetrahydrophthalides