title: Giant Negative Area Compressibility Tunable in a Soft Porous Framework Material.
abstract: A soft porous material [Zn(L)2(OH)2]n·Guest (where L is 4-(1H-naphtho[2,3-d]imidazol-1-yl)benzoate, and Guest is water or methanol) exhibits the strongest ever observed negative area compressibility (NAC), an extremely rare property, as at hydrostatic pressure most materials shrink in all directions and few expand in one direction. This is the first NAC reported in metal-organic frameworks (MOFs), and its magnitude, clearly visible and by far the highest of all known materials, can be reversibly tuned by exchanging guests adsorbed from hydrostatic fluids. This counterintuitive strong NAC of [Zn(L)2(OH)2]n·Guest arises from the interplay of flexible [-Zn-O(H)-]n helices with layers of [-Zn-L-]4 quadrangular puckered rings comprising large channel voids. The compression of helices and flattening of puckered rings combine to give a giant piezo-mechanical response, applicable in ultrasensitive sensors and actuators. The extrinsic NAC response to different hydrostatic fluids is due to varied host-guest interactions affecting the mechanical strain within the range permitted by exceptionally high flexibility of the framework.
authors.affiliation: †Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznań, Poland.
authors.forename: Weizhao
authors.initials: W
authors.lastname: Cai
authors.affiliation: †Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznań, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Gładysiak
authors.affiliation: †Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznań, Poland.
authors.forename: Michalina
authors.initials: M
authors.lastname: Anioła
authors.affiliation: ‡Department of Chemistry and Polymer Science, University of Stellenbosch, Stellenbosch 7600, South Africa.
authors.forename: Vincent J
authors.initials: VJ
authors.lastname: Smith
authors.affiliation: ‡Department of Chemistry and Polymer Science, University of Stellenbosch, Stellenbosch 7600, South Africa.
authors.forename: Leonard J
authors.initials: LJ
authors.lastname: Barbour
authors.affiliation: †Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznań, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Katrusiak
mesh_terms: D001565:Benzoates / Q000737:chemistry; D006874:Hydrostatic Pressure; D055595:Mechanical Phenomena; D000432:Methanol / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D016062:Porosity; D013314:Stress, Mechanical; D014867:Water / Q000737:chemistry; D015032:Zinc / Q000737:chemistry
chemical_list: D001565:Benzoates; D009942:Organometallic Compounds; D014867:Water; D015032:Zinc; D000432:Methanol