Single-crystal-to-single-crystal breathing and guest exchange in Co^II metal–organic frameworks

Abstract

Single-crystal-to-single-crystal (SCSC) breathing and guest exchange properties of a series of Co^II metal–organic frameworks (MOFs) are reported. A new bis-pyridyl-bis-amide ligand, namely 4,4′-oxybis(N-(pyridine-4-yl)benzamide) (LP1), produced two MOFs, namely [{Co(LP1)(IPA)}(DMF)₂(H₂O)]_∞ (1) and [{Co₂(LP1) ₂(TPA)₂}(DMF)_4∞ (2) under solvothermal conditions (IPA = isophthalate, TPA = terephthlate). While 1 showed excellent SCSC breathing responsive to both heat and guests (acetone, DMSO, MeOH, DEF), 2 displayed no breathing under similar conditions. However, it showed excellent SCSC guest (acetone, DMSO) exchange properties. Single-crystal structural analyses revealed that the conformational flexibility of the ligand LP1 played a crucial role both in breathing in 1 and in guest exchange in 2. Compound 1 also displayed heat responsive magnetic changes.