AbstractThe hydrothermal reactions of Zn(ClO4)2·6H2O and Cd(ClO4)2·6H2O with 1,3‐bis(2H‐tetrazol‐5‐yl)benzene in an aqueous ethanol and an aqueous methanol/pyridine medium, respectively, yielded a 3D and a 2D metal‐organic coordination framework [Zn(1,3‐BTB)] (1) and [Cd(1,3‐BTB)2(Py)2(H2O)2] [Cd[Cd(Py)(H2O)]2(1,3‐BTB)2] (2) (1,3‐BTB = 1,3‐ditetrazolylbenzene, Py = pyridine), respectively. Species 1 possesses an open network structure with no guest molecules residing in its small cavities. The structural characterisation of 2 shows a 2D layered framework consisting of nano‐sized polytube structures which are stacked one on top of another in the (110) plane giving small channels along the b and c axes. Additionally, compounds 1 and 2 exhibit strong fluorescence at room temperature in the solid state. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)