Versatile Tailoring of Paddle-Wheel ZnII Metal-Organic Frameworks through Single-Crystal-to-Single-Crystal Transformations

• Published in: Chemistry : a European journal 2015-11, Vol.21 (45), p.16083-16090
• Main Authors: Pal, Tapan K., Neogi, Subhadip, Bharadwaj, Parimal K.
• Format: Article
• Language: English
• Subjects: carboxylate ligands; Chemistry; Coordination polymers; Exchanging; layered compounds; Ligands; Metal ions; Metal-organic frameworks; metalation; Polymers; Single crystals; Solvents; zinc
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201502648

A new tetracarboxylate ligand having short and long arms formed 2D layer ZnII coordination polymer 1 with paddle‐wheel secondary building units under solvothermal conditions. The framework undergoes solvent‐specific single crystal‐to‐single crystal (SC‐SC) transmetalation to produce 1Cu. With a sterically encumbered dipyridyl linker, the same ligand forms non‐interpenetrated, 3D, pillared‐layer ZnII metal–organic framework (MOF) 2, which takes part in SC‐SC linker‐exchange reactions to produce three daughter frameworks. The parent MOF 2 shows preferential incorporation of the longest linker in competitive linker‐exchange experiments. All the 3D MOFs undergo complete SC‐SC transmetalation with CuII, whereby metal exchange in different solvents and monitoring of X‐ray structures revealed that bulky solvated metal ions lead to ordering of the shortest linker in the framework, which confirms that the solvated metal ions enter through the pores along the linker axis. Tailored MOFs: 2D and 3D ZnII‐containing metal–organic frameworks (MOFs) were synthesized with a new tetracarboxylate ligand. The 2D compound undergoes solvent‐specific single‐crystal‐to‐single‐crystal (SC‐SC) transmetalation, and the 3D MOF undergoes a number of linker‐exchange reactions and transmetalation with CuII ions in an SC‐SC manner. In the transmetalation reactions, solvated CuII ions enter through the pores along the linker axis, as was proven crystallographically.