Organometallic framework

A metal-organic framework comprising a metal ion, a first ligand, a second ligand, and an optional third ligand, wherein

• the metal ion is an aluminum ion,
• the first ligand is an organic compound ion consisting of a first heterocycle having two carboxyl groups, and a heteroatom composing the first heterocycle is present in the first ligand on the minor angle side of the angle created by the two carboxyl groups,
• the second ligand is an organic compound ion different from the first ligand and having two carboxyl groups, and a heteroatom composing the second heterocycle is present in the second ligand on the major angle side of the angle created by the two carboxyl groups,
• the third ligand is an organic compound ion different from the first ligand and the second ligand and having two carboxyl groups, and
• relative to the total of the first ligand, the second ligand, and the third ligand,
• the first ligand is present in a percentage of more than 0 mol % to 70 mol %,
• the second ligand is present in a percentage of more than 0 mol % to 90 mol %,
• and the third ligand is present in a percentage of 0 mol % to 80 mol %.