The catalytic profile and function of each component of a molybdenum-graphene based catalyst (Mo/N-doped graphene) for nitrogen fixation, which combines the merits of these two components, is evaluated computationally. The Mo/N part acts as an active centre for N2 bond breaking and the graphene part works as an electron transmitter and electron reservoir.
In this study, it was, interestingly, found that 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulfonate (ABTS), a widely used electron shuttle, could greatly accelerate the oxidation of substituted phenols by potassium permanganate (Mn(VII)) in aqueous solutions at pH 5-9. This was attributed to the fact that these substituted phenols could be readily oxidized by the stable radical cation (ABTS(•+)), which was quickly produced from the oxidation of ABTS by Mn(VII). The reaction of Mn(VII) with ABTS exhibited second-order kinetics, with stoichiometries of ∼5:1 at pH 5-6 and ∼3:1 at pH 7-9, and the rate constants varied negligibly from pH 5 to 9 (k = (9.44 ± 0.21) × 10(4) M(-1) s(-1)). Comparatively, the reaction of ABTS(•+) with phenol showed biphasic kinetics. The second-order rate constants for the reactions of ABTS(•+) with substituted phenols obtained in the initial phase were strongly affected by pH, and they were several orders of magnitude higher than those for the reactions of Mn(VII) with substituted phenols at each pH. Good Hammett-type correlations were found for the reactions of ABTS(•+) with undissociated (log(k) = 2.82-4.31σ) and dissociated phenols (log(k) = 7.29-5.90σ). The stoichiometries of (2.2 ± 0.06):1 (ABTS(•+) in excess) and (1.38 ± 0.18):1 (phenol in excess) were achieved in the reaction of ABTS(•+) with phenol, but they exhibited no pH dependency.
Reaction of Cd(NO3)2·4H2O
with 5-fluoro-1,3-bis[2-(4-pyridyl)ethenyl]benzene
(5-F-1,3-bpeb) and 1,3-benzenedicarboxylic acid (1,3-H2BDC) under the solvothermal conditions gave rise to a two-dimensional
metal–organic framework (MOF) [{Cd2(5-F-1,3-bpeb)2(1,3-BDC)2}·0.5DMF·2H2O]
n
(1). Compound 1 was postmodified by a photodimerization reaction between
5-F-1,3-bpeb ligands to yield [{Cd2(syn-dftpmcp)(1,3-BDC)2}·0.5DMF·H2O]
n
(syn-dftpmcp = syn-3,4,12,13-tetrakis(4-pyridyl)-8,17-bisfluoro-1,2,9,10-diethano[2.2]metacyclophane)
(2). Compounds 1 and 2 have
2D networks built from linking one-dimensional [Cd2(1,3-BDC)2]
n
chains via 5-F-1,3-bpeb or syn-dftpmcp bridges. After such a post-synthetic modification,
compound 2, relative to 1, can probe Al3+ by using a luminescent quenching approach with much higher
selectivity and sensitivity.
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