title: Isolation and evolution of labile sulfur allotropes via kinetic encapsulation in interactive porous networks.
abstract: The isolation and characterization of small sulfur allotropes have long remained unachievable because of their extreme lability. This study reports the first direct observation of disulfur (S2) with X-ray crystallography. Sulfur gas was kinetically trapped and frozen into the pores of two Cu-based porous coordination networks containing interactive iodide sites. Stabilization of S2 was achieved either through physisorption or chemisorption on iodide anions. One of the networks displayed shape selectivity for linear molecules only, therefore S2 was trapped and remained stable within the material at room temperature and higher. In the second network, however, the S2 molecules reacted further to produce bent-S3 species as the temperature was increased. Following the thermal evolution of the S2 species in this network using X-ray diffraction and Raman spectroscopy unveiled the generation of a new reaction intermediate never observed before, the cyclo-tri-sulfur dication (cyclo-S3 (2+)). It is envisaged that kinetic guest trapping in interactive crystalline porous networks will be a promising method to investigate transient chemical species.
authors.affiliation: Division of Advanced Materials Science, Pohang University of Science and Technology, RIST Building 3-3390, 77 Cheongam-Ro, Nam-Gu, Pohang, Republic of Korea.
authors.forename: Hakuba
authors.initials: H
authors.lastname: Kitagawa
authors.affiliation: Division of Advanced Materials Science, Pohang University of Science and Technology, RIST Building 3-3390, 77 Cheongam-Ro, Nam-Gu, Pohang, Republic of Korea; Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, Japan.
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Ohtsu
authors.affiliation: School of Chemical Engineering and Analytical Science, University of Manchester, The Mill, Sackville Street, Manchester M13 9PL, England.
authors.forename: Aurora J
authors.initials: AJ
authors.lastname: Cruz-Cabeza
authors.affiliation: Division of Advanced Materials Science, Pohang University of Science and Technology, RIST Building 3-3390, 77 Cheongam-Ro, Nam-Gu, Pohang, Republic of Korea; Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Kawano
keywords: MOFs; X-ray diffraction; allotropes; coordination polymers; kinetic trapping; metal–organic frameworks; porous coordination networks; sulfur; transient chemical species