An unprecedented twofold interpenetrated layered metal-organic framework with a two-dimensional 3,6-connected net topology has been prepared using a tricarboxylic acid as a 3-connected node and a Zn4O(COO)(6) cluster as a 6-connected node, where the ligand flexibility and the combination of pi-pi stacking and hydrogen bonding interactions render the 6-connected node into a topological trigonal prismatic node.