title: Single-Crystal to Single-Crystal Linker Substitution, Linker Place Exchange, and Transmetalation Reactions in Interpenetrated Pillared-Bilayer Zinc(II) Metal-Organic Frameworks.
abstract: A twofold interpenetrated pillared-bilayer framework, {[Zn3 (L)2 (L2 )(DMF)]⋅(18DMF)(6H2 O)}n (1), has been synthesized from the ligands tris(4'-carboxybiphenyl)amine (H3 L) and 1,2-bis(4-pyridyl)ethylene (L2 ). The structure contains [Zn3 (COO)6 ] secondary building units (SBUs), in which three Zn(II) ions are almost linear with carboxylate bridging. This framework undergoes reversible pillar linker substitution reactions at the terminal Zn(II) centers with three different dipyridyl linkers of different lengths to afford three daughter frameworks, 2-4. Frameworks 2-4 are interconvertible through reversible linker substitution reactions. Also, competitive linker-exchange experiments show preferential incorporation of linker L3 in the parent framework 1. The larger linker L5 does not undergo such substitution reactions and framework 5, which contains this linker, can be synthesized solvothermally as a twofold interpenetrated structure. Interestingly, when framework 5 is dipped in a solution of L3 in DMF, linker substitution takes place as before, but linker L5 now moves and diagonally binds two Zn(II) centers to afford 6 as a nonpenetrated single framework. This linker place exchange reaction is unprecedented. All of these reactions take place in a single-crystal to single-crystal (SC-SC) manner, and have been observed directly through X-ray crystallography. In addition, each 3D framework undergoes complete copper(II) transmetalation.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016 (India).
authors.forename: Dinesh
authors.initials: D
authors.lastname: De
authors.affiliation: Inorganic Materials & Catalysis Division, Central Salt and Marine Chemicals Research Institute (CSIR), Bhavnagar-364002, Gujarat (India).
authors.forename: Subhadip
authors.initials: S
authors.lastname: Neogi
authors.affiliation: Departament de Química Inorgànica i, Institut de Nanociència i Nanotecnologia, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain).
authors.forename: E Carolina
authors.initials: EC
authors.lastname: Sañudo
authors.affiliation: Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016 (India). pkb@iitk.ac.in.
authors.forename: Parimal K
authors.initials: PK
authors.lastname: Bharadwaj
keywords: linker place exchange (LPE) reaction; linker substitution; metal exchange; metal-organic frameworks; structure elucidation