Pincer complexes are useful tools for organic synthesis. Their high stability and easy functionalization have allowed the development of novel catalytic systems that have had a tremendous impact in different areas of chemistry. Thus, catalytic reactions are nowadays a fundamental part of several synthetic routes, as they allow “greener” procedures with high atom efficiency. In this context, pincer complexes have contributed to the establishment of novel and efficient catalytic reactions. Thus, herein we summarize the most recent relevant advances involving pincer complexes as catalysts.

Three Ni(ii)-POCOP pincer complexes [NiCl{CH-4-OH-2,6-(OPPh)}], 1; [NiCl{CH-4-OH-2,6-(OPtBu)}], 2 and [NiCl{CH-4-OH-2,6-(OPiPr)}], 3 were studied as bifunctional molecular sensors for inorganic anions and acetate. In CHCN, fluoride generates a bathochromic shift with a colorimetric change for 1-3 with a simultaneous fluorescence turn on, this optical effect is based on deprotonation of the para-hydroxy group of the POCOP ligand. On the other hand, in a neutral aqueous solution of 80 vol% CHCN, additions of cyanide produce a distinct change of color by forming very stable complexes with the nickel-based receptors 1-3 with log K in the range of 4.38-5.03 M and pronounced selectivity over other common anions such as iodide, phosphate, and acetate. Additionally, bromide shows a modest spectral change and affinity, but lower than those observed for cyanide. On the basis of H NMR experiments, UV-vis titrations, ESI-MS experiments, and the crystal structure of the neutral bromo complex of 1, it is proposed that the colorimetric change involves an exchange of chloride by CN on the Ni(ii) atom. The Ni(ii)-based sensor 1 allows the fluorescent selective detection of fluoride with a limit of 5.66 μmol L and colorimetric sensing of cyanide in aqueous medium in the micromolar concentration range.

Biological catecholamines such as L-DOPA and dopamine play vital physiological roles in brain, and are chemical indicators of human diseases. A new range of fluorescent Zn(II)-terpyridine complexes are described and...

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The stoichiometric control of the reaction of phloroglucinol with different chlorophosphines ClPR 2 , R = iPr (1), tBu (2) or Ph (3), leads to the direct and high yield synthesis of the p-hydroxy functionalized POCOP ligands [C 6 H 3 -5-OH-1,3-(OPR 2 ) 2 ]. Typical reactions of these compounds with NiCl 2 Á6H 2 O provide a facile access to the corresponding POCOP pincer derivatives [NiCl{C 6 H 2 -4-OH-2,6-(OPR 2 ) 2 }], R = iPr (4), tBu (5) or Ph (6).