title: Structural Tuning of Anion-Templated Motifs with External Stimuli through Crystal-to-Crystal Transformation.
abstract: Protonation of trans-1,2-bis(4-pyridyl)ethylene (4,4'-bpe) with dilute sulfuric acid (33 %) afforded a protonated adduct [{4,4'-bpe⋅2 H+}2{HSO4}-2{SO4}-2{H2O}2] (1). The neighboring olefinic bond in 1 is in a suitable range (3.931-4.064 Å) to undergo a photochemical [2+2] cycloaddition reaction. Upon irradiation with UV light (365 nm), 1 undergoes a molecular sliding involving the 4,4'-bpe⋅2 H+units, affording 2, stabilized through OSO4⋅⋅⋅π interactions. Heating 1 to 50° C leads to a 3D hydrogen-bonded organic framework (HOF) (3). This process occurs through thermal dissociation of the bisulfate anion. Diffusion of iodine through the crystal lattice of 1 and 3 enables the reduction of sulfate to bisulfate, affording a 1D hydrogen-bonded chain (4). Solid-state13C CPMAS NMR, IR, DSC, and powder XRD studies further support stimuli-responsive structural tuning through crystal-to-crystal transformation. All these conversions occur with significant translational and rotational movements along with a series of bond-breaking and bond-forming processes.
authors.affiliation: School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, PO Jatni, Khurda, 752050, Odissa, India.
authors.forename: Ashutosh S
authors.initials: AS
authors.lastname: Singh
authors.affiliation: School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, PO Jatni, Khurda, 752050, Odissa, India.
authors.forename: Ranjay K
authors.initials: RK
authors.lastname: Tiwari
authors.affiliation: Institute of Chemistry, Academia Sinica, Nangang, 115, Taipei, Taiwan, ROC.
authors.forename: Mandy M
authors.initials: MM
authors.lastname: Lee
authors.affiliation: School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, PO Jatni, Khurda, 752050, Odissa, India.
authors.forename: Jogendra N
authors.initials: JN
authors.lastname: Behera
authors.affiliation: Institute of Chemistry, Academia Sinica, Nangang, 115, Taipei, Taiwan, ROC.
authors.forename: Shih-Sheng
authors.initials: SS
authors.lastname: Sun
authors.affiliation: School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, PO Jatni, Khurda, 752050, Odissa, India.
authors.forename: V
authors.initials: V
authors.lastname: Chandrasekhar
keywords: bisulfate; crystal-to-crystal transformation; hydrogen-bonded organic frameworks; porous materials; sulfate