2025

Tamm, Jevgenija; Kaabel, Sandra; Shubin, Kirill; Ward, Jas S.; Adamson, Jasper; Aav, Riina

The cobalt-based framework {[Co1.5(TTPA)(BTC)(H2O)]2·13 H2O}n (Cobalt-MOF), assembled from tris(4-(1 H-1,2,4-triazol-1-yl)phenyl)amine (TTPA) and trimesic acid (BTC), was investigated for its capacity for guest inclusion and its stability during solvent exchange. Seven solvents were tested to replace residual DMF in as-synthesised crystals. The 1H-NMR spectra were used to assess solvent exchange kinetics and the structural integrity was probed by single-crystal X-ray diffraction. Pyridine caused framework degradation, while chloroform and dioxane achieved significant exchange without major pore collapse. Cyclohexane showed the most promising profile for preserving crystallinity and facilitating guest inclusion. Incorporation of isosorbide as a guest was confirmed by NMR analysis, revealing a bi-exponential decay rate during sorption suggestive of bulk solvent exchange and subsequent conformational rearrangement of the guest inside the MOF pores during adsorption. These findings underline the importance of solvent choice in preserving MOF integrity and enabling guest capture, reinforcing Cobalt-MOF’s potential as a crystalline sponge for small organic analytes.