1891-17-4Relevant articles and documents
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Goodwin,Sylva
, p. 217,224 (1967)
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Solvent extraction of americium(iii) and europium(iii) with tridentate N,N-dialkyl-1,10-phenanthroline-2-amide-derived ligands: extraction, complexation and theoretical study
Cao, Shiwei,Wang, Jieru,Tan, Cunmin,Zhang, Xin,Li, Sa,Tian, Wei,Guo, Hangxu,Wang, Lei,Qin, Zhi
, p. 10560 - 10568 (2016)
The extraction and complexation behavior of soft-hard combined N,N-dialkyl-1,10-phenanthroline-2-amide (PTA) ligands with Am(iii) and Eu(iii) in HNO3 solution was investigated. The effects of acidity of the aqueous solution, shaking time, concentration of the extractant and temperature on the distribution ratios were studied. The extraction ability for both Am(iii) and Eu(iii) was found to decrease with an increase in the length of the substituent alkyl chains, and the highest extractability and selectivity for Am(iii) over Eu(iii) were found for the diethyl-substituted ligand. The separation factor for Am(iii) over Eu(iii) reached around 7.6 at low acidity and high salinity. UV-vis titrations revealed that the dialkyl-substituted tridentate PTAs all predominantly formed 1?:?1 complexes with Eu(iii), which agreed well with the results of slope analyses in the extraction experiments. The stability constants (KEuL) as well as the protonation constants (KH) were also determined by UV-vis titration. Computational chemistry gave a good explanation of the relationship between the alkalinity and the protonation energy of the proposed PTA ligands. Density functional theory (DFT) calculations on the optimized structures of Am(iii) and Eu(iii) complexes with C2-PTA showed that the selectivity may originate from differences in the degree of covalency of the bonds between the metal ions and the donor N atoms, which fits well with the experimental results.
A single iron porphyrin shows ph dependent switch between "push" and "pull" effects in electrochemical oxygen reduction
Bhunia, Sarmistha,Dey, Abhishek,Dey, Somdatta Ghosh,Mukherjee, Sudipta,Nayek, Abhijit
, p. 14564 - 14576 (2020/11/02)
The "push-pull"effects associated with heme enzymes manifest themselves through highly evolved distal amino acid environments and axial ligands to the heme. These conserved residues enhance their reactivities by orders of magnitude relative to small molecules that mimic the primary coordination. An instance of a mononuclear iron porphyrin with covalently attached pendent phenanthroline groups is reported which exhibit reactivity indicating a pH dependent "push"to "pull"transition in the same molecule. The pendant phenanthroline residues provide proton transfer pathways into the iron site, ensuring selective 4e-/4H+ reduction of O2 to water. The protonation of these residues at lower pH mimics the pull effect of peroxidases, and a coordination of an axial hydroxide ligand at high pH emulates the push effect of P450 monooxygenases. Both effects enhance the rate of O2 reduction by orders of magnitude over its value at neutral pH while maintaining exclusive selectivity for 4e-/4H+ oxygen reduction reaction.
Substituted phenanthrolines as antennae in luminescent EuIII complexes
Akerboom, Sebastiaan,Van Den Elshout, Jos J. M. H.,Mutikainen, Ilpo,Siegler, Maxime A.,Fu, Wen Tian,Bouwman, Elisabeth
supporting information, p. 6137 - 6146 (2014/01/06)
Eight novel europium(III)-based coordination compounds with 1,10-phenanthroline (phen) ligands with a chloro, methoxy, ethoxy, cyano, carboxylic acid, methyl carboxylate, ethyl carboxylate, and amino substituent on the 2-position have been prepared in yields ranging from 43 to 89 %. Additionally, one lanthanum(III) coordination compound of 2-amino-1,10- phenanthroline has been isolated. All compounds have the general formula [Ln(L)2(NO3)3], except for the compound with the carboxylate ligand, which has the formula [Eu(O2Cphen) 3]. Three of the EuIII complexes as well as the La III compound crystal structures have been determined, all of which show similar N4O6 coordination spheres for the Ln III ion. Seven compounds exhibit bright luminescence that is characteristic of EuIII upon irradiation with near-UV radiation, thus indicating efficient ligand-to-metal energy transfer. The complex with 2-amino-1,10-phenanthroline is nonluminescent. The solid-state photoluminescent quantum yields range from 10 to 79 %, and the luminescence lifetimes vary from 0.43 to 1.57 ms. Analysis of the spectral intensities with the Judd-Ofelt theory shows a significant contribution of nonradiative processes that quench the luminescence of the 5D0 level on EuIII. Eight new EuIII complexes with 1,10-phenanthroline ligands substituted on the 2-position have been prepared, analyzed, and the photoluminescence properties studied. The complex with the 2-chloro substituent exhibits bright photoluminescence with a high quantum yield of 78 %. The complex with the 2-amino substituent is nonluminescent. Copyright
