X-ray diffraction study on monolayer and capillary-condensed acetonitrile in mesoporous MCM-41 at low temperatures

► An X-ray diffraction study was performed on monolayer and capillary condensed acetonitrile confined in MCM-41. ► Acetonitrile molecules are strongly bound to the silanol group of the surface with an NO distance of ~ 2.6 Å. ► The structure of monolayer acetonitrile is almost independent of temperature at 298-200 K. ► The structure of acetonitrile in the central part of pores is similar to that in bulk.