Effect of the ligand functionalization on the acid–base properties of flexible MOFs

摘要: Abstract The nature of the sites contributing to acid–base properties functionalized highly flexible MIL-53(Fe)–X MOFs, X = CH3, Cl, Br was assessed by Infrared measurements using propyne as a probe molecule since it could act proton acceptor via its C triple bond and donor through H group. These experiments performed in wide range concentration were coupled with Density Functional Theory (DFT) calculations for all propyne/MIL-53(Fe) systems based on structures simulated from situ X-ray Powder diffraction data. This joint experimental-modeling approach evidenced that bridging hydroxyl groups present MOF structure free any intra-framework interactions play preponderant role interaction hydrogen but also basic O atom MIL-53(Fe) solids. For X = Cl Br, an additional is at higher concentration, involving halogen atom, which plays site toward propyne. findings are further discussed light complementary experimental data issued gravimetry microcalorimetry measurements.