A Series of Trifacial Pd 6 Molecular Barrels with Porphyrin Walls

• Published in: Chemistry : a European journal 2012-07, Vol.18 (31), p.9571-9579
• Main Authors: Bar, Arun Kumar, Mohapatra, Sudip, Zangrando, Ennio, Mukherjee, Partha Sarathi
• Format: Article
• Language: English
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201201077

Three new nanoscopic trigonal prisms, [(tmen) 6 Pd 6 (H 2 L) 3 ](NO 3 ) 12 ( 1 ), [(Meen) 6 Pd 6 (H 2 L) 3 ](NO 3 ) 12 ( 2 ), and [(2,2′‐bipy) 6 Pd 6 (H 2 L) 3 ](NO 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 ](NO 3 ) 12 ( 1 a ), [(Meen) 6 Pd 6 (ZnL) 3 ](NO 3 ) 12 ( 2 a ), and [(2,2′‐bipy) 6 Pd 6 (ZnL) 3 ](NO 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.