Synthese und Charakterisierung poröser Al-Monocarboxylate als nachhaltige Alternative zu porösen Al-Polycarboxylaten

The present work addresses the synthesis and characterization of aluminum carboxylates and is divided into two topics. Using high-throughput methods, new porous Al-monocarboxylates using aliphatic carboxylic acids as the reactant were discovered and the synergistic effects of coordination and pH modulation were systematically investigated for controlling the particle size of established aluminum-based metal-organic frameworks (Al-MOFs). In the first part, the synergistic effect of different mono- and dicarboxylic acids (acetic acid, malonic acid, and oxalic acid) as coordination modulators and NaOH as a pH modulator on the particle size of Al-MOFs was elucidated. This enabled the synthesis of both large single crystals and nanoparticles, and the determination of their particle size dependent CO₂ sorption properties using optical calorimetry. A detailed study of Al-MIL-53-NO₂ using time-resolved magic-angle-spinning (MAS) NMR spectroscopy showed that the molar ratio of coordination modulator to pH modulator governs the stepwise deprotonation of the linker during crystallization, thereby controlling nucleation rates and crystal growth kinetics. The second part of this work addresses the lead question of whether porous Al-monocarboxylates containing naturally occurring monocarboxylic acids (e.g. acetic acid, glycolic acid) can be employed as a sustainable alternative to the synthesis of porous aluminum polycarboxylates. Using acetic acid in a high-throughput investigation of the chemical system Al3+ / NaOH / H2O eight aluminum acetates (Al-acetates) with four distinct structural motives were obtained phase pure, characterized and structurally elucidated. The use of glycolic acid, a hydroxyl-functionalized monocarboxylic acid led to the formation of a series of new mixed-metal Na-M(III)-MOFs.