Dynamic and redox active pillared bilayer open framework: single-crystal-to-single-crystal transformations upon guest removal, guest exchange, and framework oxidation.

A metal-organic pillared bilayer open framework having 3D channels, [Ni(2)(C(26)H(52)N(10))](3)[BTC](4).6C(5)H(5)N.36H(2)O (BOF-1, 1), has been assembled from bismacrocyclic nickel(II) complex [Ni(2)(C(26)H(52)N(10))(Cl)(4)].H(2)O and sodium 1,3,5-benzenetricarboxylate (Na(3)BTC). The channels are occupied by pyridine and water guest molecules. When the single crystal of 1 was dried in air and then heated at 75 degrees C for 1.5 h, respectively, [Ni(2)(C(26)H(52)N(10))](3)[BTC](4).30H(2)O (1') and [Ni(2)(C(26)H(52)N(10))](3)[BTC](4).4H(2)O (2) resulted with retention of the single crystallinity. The X-ray structures reveal spongelike dynamic behavior of the bilayer framework that reduces the interlayer distance in response to the amount of guest molecules. Solid 2 differentiates various alcohols. When 1 was immersed in pyridine and benzene, guest molecules were exchanged with retention of the single-crystal nature to give rise to [Ni(2)(C(26)H(52)N(10))](3)[BTC](4).20pyridine.6H(2)O (3) and [Ni(2)(C(26)H(52)N(10))](3)[BTC](4).14benzene.19H(2)O (4), respectively. Furthermore, crystal 1 reacted with I(2) via single-crystal-to-single-crystal transformation to produce [Ni(2)(C(26)H(52)N(10))](3)[C(9)H(3)O(6)](4)(I(3))(4).nI(2).17H(2)O (5) that consists of positively charged framework incorporating nickel(III) and nickel(II) ions and the channels including I(3)(-) and I(2).