Streamlined In Situ X-ray Crystallography of Gas Sorption State as Realized through the De Novo Development of a Novel Crystal Mount

In situ X-ray crystallography of gas sorption states is a powerful approach to gain profound insights into the nature of gas sorption phenomena, and its implementation is quite skillful. To broaden the range of implementation choices and also to further facilitate and generalize in situ X-ray crystallographic analysis under a gas atmosphere, we have carried out the de novo design and development of a novel crystal mount (NCM), which encompasses the following four features: (1) the NCM is designed to be as compact as possible in order not to interfere with the incident X-ray beam of a laboratory diffractometer. (2) The inside of a capillary fixed to the NCM is easily evacuated by a vacuum pump. (3) A target gas is also easily introduced into the capillary containing a single crystal. (4) Gas pressure is freely adjustable up to 3.9 atm. As a case study, the NCM was subjected to in situ X-ray crystallography under a CO₂ atmosphere, and we fully succeeded in analyzing the CO₂ sorption state of a dipeptide-based molecular crystal. The present de novo development of an NCM with versatility and ease of handling would open new opportunities for in situ X-ray crystallography.