“…Post- or presynthetic functionalization of MOFs is a very promising area of MOF research [109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126]. Ahnfeldt et al [125] made use of solid-state heteronuclear 1 H– 15 N, 1 H– 13 C, and homonuclear 1 H– 1 H correlation spectroscopy in order to prove the methylation of NH 2 groups in Christian-Albrechts-University-1 (CAU-1) derivatives.…”