The relaxation dynamics of polyisoprene (PI) and nitrile butadiene rubber (NBR) chains at the SiO2 interface were directly probed as a function of distance from the SiO2 surface using time-resolved evanescent wave-induced fluorescence anisotropy, dielectric relaxation spectroscopy, and sum-frequency generation spectroscopy. We found the presence of the dynamics gradient of chains in the interfacial region with the SiO2 surface and tried to assign it to the two kinds of adsorbed chains, namely, loosely and strongly adsorbed, at the interface. The segmental relaxation of chains in the strongly adsorbed layer at the interface could be slower than that of bulk chains by more than 10 orders.

Rhodium complexes bearing an anionic pyrrole-based PNP-type pincer ligand are synthesised and found to work as effective catalysts for the transformation of molecular dinitrogen into tris(trimethylsilyl)amine under mild reaction conditions.

Molybdenum complexes bearing an anionic pyrrole-based PNP-type pincer ligand have been prepared and have been found to work as catalysts for the conversion of N2 into NH3 under ambient conditions.

No abstract

The rotational relaxation time (τrot) of a fluorescent molecule, coumarin 153 (C153), dispersed in different rubbery polymers is characterized by time‐resolved fluorescence anisotropy measurement, and an attempt is made to quantitatively combine it with the segmental relaxation time (τseg) of the corresponding matrix polymer obtained by dielectric relaxation spectroscopy. This study here demonstrates that τseg extrapolated to higher temperatures using the Vogel–Fulcher–Tammann law can be superimposed on τrot, resulting in a single curve. This behavior is common for polymers with different glass transition temperatures such as polyisoprene and acrylonitrile/butadiene copolymer, implying that the rotational dynamics of C153 is a useful tool for the characterization of polymer dynamics.

Among synthetic models of nitrogenases, iron-dinitrogen complexes with a Fe-C bond have attracted increasing attention in recent years. Here we report the synthesis of square-planar iron(I)-dinitrogen complexes supported by anionic benzene-based PCP-and POCOP-type pincer ligands as carbon donors. These complexes catalyze the formation of ammonia and hydrazine from the reaction of dinitrogen (1 atm) with a reductant and a proton source at −78 °C, producing up to 252 equiv of ammonia and 68 equiv of hydrazine (388 equiv of fixed N atom) based on the iron atom of the catalyst.Anionic iron(0)-dinitrogen complexes, considered an essential reactive species in the catalytic reaction, are newly isolated from the reduction of the corresponding iron(I)-dinitrogen complexes.This study examines their reactivity using experiments and DFT calculations.

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The synthesis of ammonia from atmospheric dinitrogen, nitrogen fixation, is one of the essential reactions for human beings. Because the current industrial nitrogen fixation depends on dihydrogen produced from fossil fuels as raw material, the development of a nitrogen fixation reaction that relies on the energy provided by renewable energy, such as visible light, is an important research goal from the viewpoint of sustainable chemistry. Herein, we establish an iridium- and molybdenum-catalysed process for synthesizing ammonia from dinitrogen under ambient reaction conditions and visible light irradiation. In this reaction system, iridium complexes and molybdenum triiodide complexes bearing N-heterocyclic carbene-based pincer ligands act as cooperative catalysts to activate 9,10-dihydroacridine and dinitrogen, respectively. The reaction of dinitrogen with 9,10-dihydroacridine is not thermodynamically favoured, and it only takes place under visible light irradiation. Therefore, the described reaction system is one that affords visible light energy–driven ammonia formation from dinitrogen catalytically.