52877-36-8Relevant articles and documents
Electrochemical CO2 Reduction-The Effect of Chalcogenide Exchange in Ni-Isocyclam Complexes
Apfel, Ulf-Peter,Battistella, Beatrice,Gerschel, Philipp,Ray, Kallol,Siegmund, Daniel
, p. 1497 - 1510 (2020/04/30)
Among the numerous homogeneous electrochemical CO2 reduction catalysts, [Ni(cyclam)]2+ is known as one of the most potent catalysts. Likewise, [Ni(isocyclam)]2+ was reported to enable electrochemical CO2 conversion but has received significantly less attention. However, for both catalysts, a purposeful substitution of a single nitrogen donor group by chalcogen atoms was never reported. In this work, we report a series of isocyclam-based Ni complexes with {ON3}, {SN3}, {SeN3}, and {N4} moieties and investigated the influence of nitrogen/chalcogen substitution on electrochemical CO2 reduction. While [Ni(isocyclam)]2+ showed the highest selectivity toward CO2 reduction within this series with a Faradaic efficiency of 86% for the generation of CO at an overpotential of-1.20 V and acts as a homogeneous catalyst, the O-and S-containing Ni complexes revealed comparable catalytic activities at ca. 0.3 V milder overpotential but tend to form deposits on the electrode, acting as precursors for a heterogeneous catalysis. Moreover, the heterogeneous species generated from the O-and S-containing complexes enable a catalytic hydride transfer to acetonitrile, resulting in the generation of acetaldehyde. The incorporation of selenium, however, resulted in loss of CO2 reduction activity, mainly leading to hydrogen generation that is also catalyzed by a heterogeneous electrodeposit.
A convenient synthesis of isocyclam and [16]aneN4 and the photophysics of their dicyanochromium(III) complexes
Grisenti, David L.,Smith, Mary beth,Fang, Luxi,Bishop, Nicholas,Wagenknecht, Paul S.
experimental part, p. 157 - 162 (2010/06/12)
The syntheses of the tetraazamacrocyclic ligands 1,4,7,11-tetraazacyclotetradecane (isocyclam) and 1,5,9,13-tetraazacyclohexadecane ([16]aneN4) in two steps starting from the corresponding tetraamine and diethylmalonate is reported. The trans-dicyanochromium(III) complexes, trans-[Cr(isocyclam)(CN)2]PF6 and trans-[Cr([16]aneN4)(CN)2]PF6 have also been prepared. Both are 2Eg emitters with 0-0 band emission wavelengths at 721.2 and 704.8 nm, respectively. The isocyclam complex has a room temperature excited state lifetime of 147 μs in aqueous solution which increases to 215 μs upon macrocyclic N-H deuteration, whereas the corresponding lifetime of the [16]aneN4 complex is 25 μs and is unaffected by macrocyclic N-H deuteration. The implications of the temperature dependence of the excited state lifetimes are also presented.
