Method for producing coordinatively unsaturated metal-organic framework and coordinatively unsaturated metal-organic framework

A method for producing a coordinatively unsaturated metal-organic framework, comprising:

• providing a precursor metal-organic framework comprising a metal cluster, and a polycarboxylic acid ion and a monocarboxylic acid ion which are coordinated to the metal cluster, and
• allowing the precursor metal-organic framework and a metal halide salt having a Lewis acidity to coexist in a solvent to desorb at least a part of the monocarboxylic acid ion which is coordinated to the metal cluster, from the metal cluster,
• wherein said coordinatively unsaturated metal-organic framework comprises;
• an M6O8-x(OH)x metal cluster, and carboxylic acid ions coordinated to the metal cluster,
• wherein M is a tetravalent group IV element ion or a rare earth ion,
• wherein the carboxylic acid ions coordinated to the metal cluster comprise a polycarboxylic acid ion as a polydentate ligand and a monocarboxylic acid ion as a monodentate ligand,
• wherein a plurality of the metal clusters are bonded to each other due to the polycarboxylic acid ion,
• wherein the amount of monocarboxylic acid ions coordinated to the metal cluster is 80% or less, when the maximum amount of monocarboxylic acid ions which can coordinate with the metal cluster is 100%, and
• wherein the maximum amount of monocarboxylic acid ions which can coordinate with the metal cluster is six for each metal cluster.