(a) View along 4-fold axis of the structure in [Zn2 (1,4-bdc)2 (dabco)]n. One {Zn2(1,4-bdc)2} 2-D layer is colored orange to emphasize the alternation of the stacking layer. Hydrogen atoms and guest molecules are omitted. (b) Space-filling representation of evacuated framework, in which the open square channels are emphasized; view along fourfold axis. (c) Side view of evacuated framework, showing the windows interconnecting the channels. (d) Space-filling representation of the metal organic framework structure in [Zn2 (1,4–bdc)2 (dabco)]n C6H6, showing rhombic-grid motif of [Zn2 (1,4–bdc)2 ] layers. The guest molecules and dabco hydrogens are not shown. Legend: Zn green, N blue, O red, C grey and H white. © 2004, Wiley-VCH [52], with permission.