1375478-14-0Relevant articles and documents
Development of a UiO-Type Thin Film Electrocatalysis Platform with Redox-Active Linkers
Johnson, Ben A.,Bhunia, Asamanjoy,Fei, Honghan,Cohen, Seth M.,Ott, Sascha
, p. 2985 - 2994 (2018)
Metal-organic frameworks (MOFs) as electrocatalysis scaffolds are appealing due to the large concentration of catalytic units that can be assembled in three dimensions. To harness the full potential of these materials, charge transport to the redox catalysts within the MOF has to be ensured. Herein, we report the first electroactive MOF with the UiO/PIZOF topology (Zr(dcphOH-NDI)), i.e., one of the most widely used MOFs for catalyst incorporation, by using redox-active naphthalene diimide-based linkers (dcphOH-NDI). Hydroxyl groups were included on the dcphOH-NDI linker to facilitate proton transport through the material. Potentiometric titrations of Zr(dcphOH-NDI) show the proton-responsive behavior via the OH groups on the linkers and the bridging Zr-μ3-OH of the secondary building units with pKa values of 6.10 and 3.45, respectively. When grown directly onto transparent conductive fluorine-doped tin oxide (FTO), 1 μm thin films of Zr(dcphOH-NDI)@FTO could be achieved. Zr(dcphOH-NDI)@FTO displays reversible electrochromic behavior as a result of the sequential one-electron reductions of the redox-active NDI linkers. Importantly, 97% of the NDI sites are electrochemically active at applied potentials. Charge propagation through the thin film proceeds through a linker-to-linker hopping mechanism that is charge-balanced by electrolyte transport, giving rise to cyclic voltammograms of the thin films that show characteristics of a diffusion-controlled process. The equivalent diffusion coefficient, De, that contains contributions from both phenomena was measured directly by UV/vis spectroelectrochemistry. Using KPF6 as electrolyte, De was determined to be De(KPF6) = (5.4 ± 1.1) × 10-11 cm2 s-1, while an increase in countercation size to n-Bu4N+ led to a significant decrease of De by about 1 order of magnitude (De(n-Bu4NPF6) = (4.0 ± 2.5) × 10-12 cm2 s-1).
Solid state assemblies of cyclic imides tethered hydroxy benzoic acids with pyridine and quinoline: Toward the formation of channels and cavities
Singh, Devendra,Baruah, Jubaraj B.
experimental part, p. 3169 - 3180 (2012/08/14)
A series of inclusion compounds of different cyclic imides tethered hydroxy-benzoic acid hosts (1-8) with guests pyridine (I-IV) and quinoline (V-X) have been prepared and structurally characterized. Supramolecular aspects pertaining to the influence of guest molecules toward the formation of solid state network structures of hosts are described. Hydrogen bonding of both carboxylic acid and hydroxyl groups as well as π???π stacking of aromatic imide units led to the formation of channels of different dimensionalities in the supramolecular architectures of I-X. In these structures, the channels are occupied by the guest molecules that interact with both hydrogen bonding groups of host molecules via different types of hydrogen bond motifs. Thermogravimetric analyses correspond to the association of different numbers of guest pyridine or quinoline molecules with isomeric hydroxy-benzoic acid hosts. Solid state fluorescence spectra of hosts 1-8 are recorded which show emissions in the region of 412-516 nm. Overall this structural study represents the combined effects of π-stacking aromatic imide synthons and two hydrogen bonding carboxylic acid and hydroxyl functional groups in the presence of aromatic nitrogen containing guests to create fascinating supramolecular architectures.
