J.R. Shakirova, E.V. Grachova, V.V. Gurzhiy, Senthil Kumar Thangaraj, J. Jänis, A.S. Melnikov, A.J. Karttunen, S.P. Tunik, I.O. Koshevoy, Heterometallic cluster-capped tetrahedral assemblies with postsynthetic modification of the metal cores Angew. Chem. Int. Ed., (2018), doi: 10.1002/anie.201809058

Взаимодействие политопных алкинильных лигандов с Au-Cu кластерами приводит к образованию трехмерных агрегатов, которые демонстрируют фосфоресценцию при комнатной температуре (Φem = 0,6). Эта люминесценция происходит из металл-центрированного возбужденного состояния вследствие переноса заряда с металла на лиганд. Супрамолекулярные Au-Cu агрегаты могут быть легко преобразованы в изоструктурные Au-Ag аналоги путем прямого обмена ионов металлов в растворе. Эта модификация меняет природу эмиссии на внутрилигандную, что представляет собой необычный пример подобного "переключения" электронной структуры для металлорганических соединений.

Abstract

Combining the star‐shaped alkynyl ligands with low‐nuclearity gold–copper triphosphane clusters produces 3D metallocage aggregates, which demonstrate room temperature phosphorescence in solution (max Φ_em=0.6). Their luminescence mainly originates from cluster‐localized metal‐to‐ligand charge transfer excited state. These supramolecular assemblies can be easily converted into the isostructural gold‐silver congeners by the direct exchange of the metal ions. Such modification of the terminal metal cores switches the emission to the intraligand (alkyne) electronic transitions of the triplet manifold, that represents an unusual optical functionality among the metallocycle/metallocage complexes.

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Dekina D.I., Kalinichev A.V., Pokhvishcheva N.V., Peshkova M.A., Mikhelson K.N. Effects of quantitative composition of the sensing phase in the response of ionophore-based optical sensors Sensors & Actuators: B. Chemical, V.277, N. 20, P. 535-543, doi: 10.1016/j.snb.2018.09.018

На основе теоретических представлений количественно проанализировано влияние состава сенсорного слоя оптодов на основе ионофоров на характеристики их отклика: рабочий диапазон и чувствительность.

Abstract

The response characteristics of the optical chemical sensors (optodes), namely response range, response span and sensitivity are quantitatively related to the composition of the sensor phase for the first time. The dependence of the characteristics of ion-selective bulk optodes on the concentrations of the indicator, ionophore and ionic additive (ion-exchanger) are simulated numerically and experimentally verified with Na⁺- and K⁺-selective colorimetric optodes. It is shown how the response span, response range, median and sensitivity depend on the sensor membrane composition. Response curves with an intermediate plateau are predicted theoretically and obtained experimentally. It is shown that the inflection point in the response curve does not necessarily refers to α = 0.5. The results can be used for the fine tuning of the optical response of chemical sensors.

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Lu, X., Du, L., Wang, D., Yang, P., Liu, L., Zhang, J., An, M., Levin, O., Wang, J., Ge, L. Highly Dispersed Cu−N_X Moieties Embedded in Graphene: A Promising Electrocatalyst towards the Oxygen Reduction Reaction, ChemElectroChem, (2018). Article in Press. DOI: 10.1002/celc.201800657

В статье предложен простой метод синтеза катализатора реакции восстановления кислорода на основе Cu-Nх допированного графена.

Abstract

Transition metal–carbon–nitrogen catalysts for the oxygen reduction reaction (ORR) are promising and challenging. Cu is a potential transition metal to form efficient ORR catalysts for fuel cells. Herein, a facile method is developed to synthesize a highly dispersed Cu−N_X and N‐doped graphene (Cu−N−G) catalyst. The Cu−N−G catalyst shows a half‐wave potential (E_1/2) of 0.859 V, which is comparable to the commercial Pt/C catalyst (0.856 V), and is among the best compared with the previously reported Cu‐based materials. In addition, such a catalyst shows good stability and methanol tolerance in alkaline media. A synergy of doped N (pyridinic and graphitic N) and Cu−N_X moieties as well as the pore structure are revealed to account for the enhanced ORR activity.