The first europium triple-decker tetrapyrrole with mixed corrole and phthalocyanine macrocycles was synthesized and characterized by spectroscopic and electrochemical methods. The molecular structure was characterized by single-crystal X-ray diffraction and showed the corrole to be in the middle of the sandwich with phthalocyanine macrocycles at each extreme.
The electrochemical properties of a new class of sandwich (phthalocyaninato)(corrolato) europium triple-decker complexes were synthesized and characterized by cyclic voltammetry in CH2Cl2 containing 0.1 M tetrabutylammonium perchlorate (TBAP) as supporting electrolyte. Two of the compounds described in the current paper are shown in the figure, and represented by HEu2[Pc(R)8]2[Cor(ClPh)3], where R = OC5H11 or OC8H17, Pc represents the dianion of phthalocyanine and Cor represents the trianion of corrole. Both triple-decker complexes exhibit five reversible oxidations and three reversible reductions, all of which are attributed to ligand-based redox processes. The half-wave potentials for the first oxidation and first and second reduction of the two europium triple-deckers are close to E
1/2 values for the double-decker species Eu[Pc(OC8H17)8]2, while half-wave potentials for the second to fifth oxidations are close to E
1/2 values for the triple-decker Eu2[Pc][Pc(OC8H17)8]2. The synthesis and electrochemical properties of the new compounds will be described.
Acknowledgment: This work was supported by the Natural Science Foundation of China (No. 21001054, 21071067) and the Robert A. Welch Foundation (K.M.K., Grant E-680).
Figure 1
The coordination chemistry of N-functionalised cyclam ligands has a rich history, yet cyclam derivatives with pendant alkynes are largely unexplored. This is despite the significant potential and burgeoning application of...
<p>Herein we describe single crystal
X-ray diffraction and spectroscopic investigations of the coordination
chemistry of copper(II) complexes of cyclam derivatives with between 1 and 4
pendant alkynes. The crystal structures of these copper complexes unexpectedly reveal
a range of coordination modes, and the surprising occurrence of five unique
complexes within a single recrystallisation of the tetra-<i>N</i>-propargyl cyclam ligand. One of these species exhibits weak
intramolecular copper-alkyne coordination, and another is formed by a surprising
intramolecular copper-mediated hydroalkoxylation reaction with the solvent
methanol, transforming one of the pendant alkynes to an enol ether. Multiple
functionalisation of the tetra-<i>N</i>-propargyl
ligand is demonstrated <i>via</i> a ‘tetra-click’
reaction with benzyl azide, and the copper-binding behaviour of the resulting
tetra-triazole ligand is characterised spectroscopically.</p>
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