Research Information System
IX. Ulusal Anorganik Kimya Kongresi, Ankara, Turkey, 16 - 19 May 2024, pp.50-51, (Summary Text)
Metal organic frameworks are hybrid particles formed by the coordination of metal nodes and
organic ligand. Researchers have shown great attention on metal organic framework structures
over decades due to their unique structure, enhanced porosity, and high surface area to volume
ratios. Particles attain unique structures in accordance with the contents of the recipe. Metal
salts have positive charge in the precursor solution and coordinate with the organic ligand
by forming building units. Different types of metal ions have different coordination numbers,
which manipulate the structure of building units. Hydrothermal and solvothermal methods are
the most preferred synthesis routes. The appropriate method should be chosen by considering
the reactive nature of salts and ligand with solvents. Oxidative agents in the precursor solution
could induce the formation of metal oxide salts and obstruct the formation of clusters.
Synthesis of metal organic framework structures is based on the appropriate selection of metal
salt and ligand.
Titanium-based nanoparticles are valuable in the pharmaceutical industry and drug delivery
studies due to their low toxicity [1]. Titanium metal salts have a coordination number of six and
can coordinate with organic ligands to form titanium-oxo-clusters. Titanium salts are unstable
by their nature and their stability varies depending on their cationic charge [2]. Selecting
the most convenient metal cation increases the stability of the cation-ligand bond for the
formation of clusters. Titanium chloride (TiCl4) and titanium alkoxide (Ti(OR)4) are the most
suitable metal salts considering that Ti+4 is the most positively charged cation of the titanium
metal. These metal salts go through a hydrolysis reaction with water or water vapor and
precipitate as titanium-oxide derivatives and hydrochloric acid (HCl) or water (H2O). Titanium
alkoxide is the most reliable metal salt for the synthesis of solid particles other than titanium
dioxide (TiO2). Hydrochloric acid is an undesirable product due to health and environmental
effects and alkoxy groups found in titanium alkoxides are more hydrophobic. Dan Hardi et al.
[3] synthesized the titanium-based metal organic framework structure MIL-125 using titaniumisopropoxide
(Ti(OCH(CH3)2)4) as the metal salt in the solvothermal route. They used a mixture
of dimethylformamide (DMF) and methanol as a solvent to prevent the formation of TiO2 and
accelerate the coordination between metal nodes and organic ligands. The scope of this study
is to optimize the conditions for the formation of MIL-125 particles with high crystallinity. We
investigated the effect of solvents on the prevention of TiO2 particles in precursor solution
and optimized the mixture conditions by considering the parameters for solubility, structural
resemblance of the metal salt and the solvents, acidity of the solvent mixture, and polarity
difference between its components. We optimized the synthesis conditions, namely the
temperature and residence time, to achieve MIL-125 particles with high crystallinity.