The crystallization proces produces solids, crystals, which are made of atoms and molecules periodically repeated in space. There are ionic, covalent, metal and molecular crystals and the difference between them is in the type of particles of which they are made and in the type of bonds. We can classify them into space groups, crystallographic point groups, Bravais lattices and finally into main crystal systems. In the 18th group of the Periodic Tablet of Elements are noble gases, helium, neon, argon, krypton, xenon and radon. Noble gases are colorless, tasteless, with no smell and in general, they do not make compounds with other elements, so basically they are inactive. In industry, noble gases are obtained by fractional distillation of liquid air, just in the way they were first isolated. Canadian, Neil Bartlett, was the first scientist who studied the inactivity of noble gases and the first who discovered noble gas compounds, fluorides. Under high pressure conditions, helium can enter into the structure of compound 4-hydroxy cyanobenzene, which rotates under the pressure and creates new interactions and the entrance for helium is allowed. Today, it is known that noble gases can fit into complex compounds. Whether it is research out of curiosity or for the common good, as is the case with xenon, the results are interesting. For the purpose of capturing noble gases, the most used are MOFs or metal organic frameworks.