Accordingly, one embodiment of the invention is a crystalline composition having a three-dimensional microporous framework structure of MA2 units, where A is sulfur or selenium and having the empirical formula expressed in molar ratios: xR:MA2???0.2 :zH2 O where R represents at least one organic templating agent present in the intracrystalline pore system, x has a value greater than 0 to about 1.0