Isoreticular Design of Two Novel Metal Organic Frameworks\nand Their Single-Crystal-to-Single-Crystal Solvent Exchange Properties

Abstract

The rational design and synthesis\nof two novel MOFs based on the\nSchiff base ligand 5-({[4′-carboxy-(1,1′-biphenyl)-4-yl]­methylene}­amino)­isophthalic\nacid (CBIPH₃) formulated as [Cd₃(CBIP)₂­(DMF)­(H₂O)₂]<i>_n</i>·8<i>n</i>DMF·4<i>n</i>H₂O, (<b>1</b>)·8<i>n</i>DMF·4<i>n</i>H₂O, and [Nd­(CΒΙP)­(DMF)­(H₂O)]<i>_n</i>·1.5<i>n</i>DMF·3<i>n</i>H₂O, (<b>2</b>)·1.5<i>n</i>DMF·3<i>n</i>H₂O, are reported.\nThe ligand CΒΙPH₃ is an extended version of\n5-[(4-carboxy­benzyli­dene)­amino]­isophthalic\nacid (CIPH₃) used previously by our group and was designed\nto isolate isoreticular analogues of compounds [Cd₃­(CIP)₂­(DMF)₃] (UCY-3) and [Nd₂­(CIP)₂­(DMF)_2.8(H₂O)_1.2] (UCY-2)\nwhich are known to possess interesting single-crystal-to-single-crystal\n(SCSC) transformation properties. Indeed, this goal was achieved,\ngiving rise to the formation of <b>1</b>·8<i>n</i>DMF·4<i>n</i>H₂O and <b>2</b>·1.5<i>n</i>DMF·3<i>n</i>H₂O exhibiting 3-D\nmicroporous structures. Compound <b>2</b> was proven to display\nsignificant flexibility and capability to exchange, via SCSC transformation\nreactions, both the coordinated solvent molecules with <i>N</i>-methylpyrrolidone (NMP) and the lattice solvent molecules with aromatic\nhydrocarbons (benzene, toluene, <i>o</i>- and <i>m</i>-xylene). As a result, five SCSC modified products were additionally\ncharacterized crystallographically. The topological features of the\nreported compounds and the effect of the SCSC solvent exchange reactions\non the structural characteristics of the pristine material are discussed\nin detail.