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, [Ni2(C26H52N10)]3[BTC]4·6C5H5N·36H2O (BOF-1, 1), has been assembled from bismacrocyclic nickel(II) complex [Ni2(C26H52N10)(Cl)4]·H2O and sodium 1,3,5-benzenetricarboxylate (Na3BTC). 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 °C for 1.5 h,
respectively, [Ni2(C26H52N10)]3[BTC]4·30H2O (1‘) and [Ni2(C26H52N10)]3[BTC]4·4H2O (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 [Ni2(C26H52N10)]3[BTC]4·20pyridine·6H2O (3) and [Ni2(C26H52N10)]3[BTC]4·14benzene·19H2O (4), respectively. Furthermore, crystal 1 reacted with I2 via single-crystal-to-single-crystal transformation to produce [Ni2(C26H52N10)]3[C9H3O6]4(I3)4·nI2·17H2O (5) that consists
of positively charged framework incorporating nickel(III) and nickel(II) ions and the channels including I3-
and I2.