A series of trifacial Pd6 molecular barrels with porphyrin walls.

Three new nanoscopic trigonal prisms, (tmen)(6) Pd(6) (H(2)L)(3)(12) (1), (Meen)(6) Pd(6)(H(2) L)(3)(12) (2), and (2,2'-bipy)(6)Pd(6) (H(2)L)(3)(12) (3), have been synthesized in excellent yields through single-step metal-ligand-coordination-driven self-assembly using 5,10,15,20-tetrakis(3-pyridyl)porphyrin (H(2)L) as a donor and cis-blocked Pd(II) 90° acceptors. These complexes were fully characterized by spectroscopic studies and single-crystal X-ray diffraction. All of these barrels quantitatively bind Zn(II) ions in the N(4) pockets of the porphyrin walls at room temperature. Their corresponding zinc-embedded complexes, (tmen)(6)Pd(6)(ZnL)(3)(12) (1 a), (Meen)(6) Pd(6)(ZnL)(3)(12) (2 a), and (2,2'-bipy)(6)Pd(6)(ZnL)(3)(12) (3 a), were synthesized under ambient conditions by the post-synthetic binding of Zn(II) ions into the H(2)N(4) pockets of the porphyrin walls of these complexes. These zinc-embedded complexes were characterized by electronic absorption, fluorescence emission, (1)H NMR spectroscopy, as well as elemental analysis. Complexes 1-3 exhibited considerable microporosity in their solid state. Complex 1 was an efficient adsorbent for nitrogen gas and EtOH, MeOH, and water vapors.