Coordination Modulation Method To Prepare New Metal–Organic Framework-Based CO-Releasing Materials

Aluminum-based metal–organic frameworks (MOFs), [Al(OH)(SDC)]n, (H2SDC: 4,4′-stilbenedicarboxylic acid), also known as CYCU-3, were prepared by means of the coordination modulation method to produce materials with different crystal size and morphology. In particular, we screened several reagent concentrations (20–60 mM) and modulator/ligand ratios (0–50), leading to 20 CYCU x_y materials (x: reagent concentration, y = modulator/ligand ratio) with different particle size and morphology. Noteworthy, the use of high modulator/ligand ratio gives rise to a new phase of CYCU-3 (CYCU-3′ x_50 series), which was structurally analyzed. Afterward, to test the potential of these materials as CO-prodrug carriers, we selected three of them to adsorb the photo- and bioactive CO-releasing molecule (CORM) ALF794 [Mo(CNCMe2CO2H)3(CO)3] (CNCMe2CO2H = 2-isocyano-2-methyl propionic acid): (i) CYCU-3 20_0, particles in the nanometric range; (ii) CYCU-3 50_5, bar-type particles with heterogeneous size, and (iii) CYCU-3′ 50_50, ...