Formation of a one-dimensional array of oxygen in a microporous metal-organic solid

We report the direct observation of dioxygen molecules physisorbed in the nanochannels of a microporous copper coordination polymer by the (maximum entropy method)/Rietveld method, using in situ high-resolution synchrotron x-ray powder diffraction measurements. The obtained MEM electron density revealed that van der Waals dimers of physisorbed O₂locate in the middle ofnanochannets and form a one-dimensional ladder structure aligned to the host channel structure. The observed O-O stretching Raman band and magnetic susceptibilities are characteristic of the confined O₂, molecules in one-dimensional nanochannets of CPL-1 (coordination polymer 1 with pillared layer structure).