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Density functional theory calculations have been performed to probe the reaction mechanism of the recently reported twofold C−H annulation of arylformamides with alkynes by Ni−Al bimetallic catalysis. The main pathway consisted of the formyl C−H activation, phenyl C−H activation, migratory insertion, and reductive elimination steps in succession. The desired annulation product was found to be the equilibrium‐controlled product, while the minor hydrocarbamoylation product was the kinetics‐controlled product. Calculated free‐energy profiles indicated that the annulation and hydrocarbamoylation pathways could intersect with each other and merge into a mechanism unity, in which the reaction system entered the hydrocarbamoylation pathway in early stage and switched to the annulation pathway afterwards via suitable transition states. The modified mechanism picture demonstrated the phenyl C−H activation step to be the rate‐determining step with a free‐energy barrier of 27.7 kcal/mol. However, this barrier was only 19.4 kcal/mol on the basis of a single annulation pathway, which could not satisfactorily agree with the experimental conditions and kinetic isotope effects. In addition, the crucial role of the bifunctional secondary phosphine oxide ligand in promoting the reactivity and selectivity was elucidated in detail. [ABSTRACT FROM AUTHOR]

A seriesof meso-ferrocenyl-porphyrin dyads linkedby four different π-conjugated bridging units (directly bound,vinyl, ethynyl, and phenyl) have been synthesized to investigate theinfluence of the conjugated linker on both the electronic and photochemicalproperties of the porphyrin chromophore. The basic structure consistsof 5-(Fc)-15-(4-methylbenzoate)-10,20-diphenylporphyrin zinc(II),where Fc = ferrocene, vinylferrocene, ethynylferrocene, or phenylferrocene.Upon introduction of the various electron-donating ferrocenyl moietiesat the meso-position of the porphyrin ring, Soretand Q-band electronic transitions of the resultant dyads are red-shiftedcompared with those of the nonferrocenyl reference porphyrin system15-(4-methylbenzoate)-10,20-diphenylporphyrin zinc(II). The electronicproperties of these systems have been investigated by electrochemical(cyclic voltammetry) and computational (DFT/TDDFT) methods, whileUV/vis absorption and fluorescence emission spectroscopic analysisis also presented. Collectively, electronic and photophysical analysisindicate a strong electronic communication between the porphyrin macrocycleand directly bound ferrocenyl, vinylferrocenyl, and ethynylferrocenyldyads. The presence of a phenyl spacer acts to inhibit such electroniccommunication due to the orthogonal geometry of the bridging phenylring at the meso-position of the porphyrin macrocycle.In addition to electronic factors, and in particular for the directlybound 5-(ferrocenyl)-15-(4-methylbenzoate)-10,20-diphenylporphyrinzinc(II) dyad, computational analysis suggests that a significantruffling of the porphyrin macrocyle from planarity is required tofacilitate the bulky ferrocene group directly at the meso-position. Of particular note for each of the meso-ferrocenyl-porphyrin dyads is how fluorescence emission derivedfrom the porphyrin S1(π–π*) excitedstate is quantitatively quenched due to photoinduced charge-transferfrom the ferrocene unit onto the excited state porphyrin. Spectroelectrochemicalstudies demonstrate redox off/on switching of the porphyrin fluorescenceemission via ferricenium/ferrocene redox cycling. Interestingly, itwas found that the S0← S1fluorescenceemission is also switched-on following titration with the metal ionsCe(IV), Cu(II), and Fe(III) in acetonitrile. [ABSTRACT FROM AUTHOR]

N,O-bidentate BF 2 complexes with five- and six-membered core rings have been thoroughly investigated. However, the development of seven-membered N,O-boron complexes is still an area to be explored. We have developed BF 3  ⋅ OEt 2 -induced self-condensation and coordination reactions based on a single starting material, which had been elucidated by experiment and calculation. This parent asymmetric core-expanded borondifluoride-(Z)-1,3-di(1H-pyrrol-2-yl)but-2-en-1-one (BOPYO) showed reactivity with a wide range of aldehydes, thus providing a series of conjugation BOPYOs. Moreover, a BOPYO derivative with a dimethylamino group was developed as a new NIR dye that responds to acid with favorable photophysical properties based on intramolecular charge transfer effect., (© 2022 Wiley-VCH GmbH.)

In this work, Fe 2 O 3 @TiO 2 nanostructures with staggered band alignment were newly designed by an aerobic oil-phase cyclic magnetic adsorption method. XRD and TEM analyses were performed to verify the uniform deposition of Fe 2 O 3 nanoparticles on the nanotube inner walls of TiO 2 . The steady-state degradation experiments exhibited that 1FeTi possessed the most superior performance, which might be ascribable to the satisfying dark adsorption capacity, efficient photocatalytic activity, ease of magnetic separation, and economic efficiency. These results indicated that the deposition of Fe 2 O 3 into TiO 2 nanotubes significantly enhanced the activity of Fe 2 O 3 , which was mainly ascribed to the Fe 2 O 3 -induced formation of staggered iron oxides@TiO 2 band alignment and thus efficient separation of h + and e - . Furthermore, the PL intensity and lifetime of the decay curve were considered as key criterions for the activity's evaluation. Finally, the leaching tests and regeneration experiments were also performed, which illustrated the inhibited photodissolution compared with TiO 2 /Fe 3 O 4 and stable cycling ability, enabling 1FeTi to be a promising magnetic material for photocatalytic water remediation.