Catalytic and Biological Activity of Silver and Gold Complexes Stabilized by NHC with Hydroxy Derivatives on Nitrogen Atoms

Marco Sirignano,Maria Stefania Sinicropi,Domenico Iacopetta,Annaluisa Mariconda,Jessica Ceramella,Pasquale Longo,Giovanni Vigliotta

doi:10.3390/catal12010018

Marco Sirignano, Maria Stefania Sinicropi + Show 5 more

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https://doi.org/10.3390/catal12010018

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Abstract

In this paper is reported the synthesis of N,N′ hydroxy derivative of NHC silver (3a–4a) and gold(I) (3b–4b) complexes of general formula [M(NHC)2]+ [MX2]−. All compounds were characterized by spectroscopic and analytic techniques. The complexes turned out to be effective in both catalytic and biological applications. They catalyzed the coupling of aldehyde, piperidine, and phenylacetylene in A3-reaction to produce propargylamines and showed antimicrobial activity. In fact, minimal inhibition concentration (MIC) tests with Gram-positive and Gram-negative bacteria demonstrated that the silver compounds are selective toward E. coli, whereas the gold analogues are active against S. aureus. Moreover, the N,N′ hydroxy derivative of NHC silver complexes 3a and 4a exhibited good anticancer activity on the HeLA cancer cells (3a-IC50 = 12.2 ± 0.1 µM, 4a-IC50 = 11.9 ± 1.2 µM), whereas gold complex 4b displayed good anticancer activity towards the MCF-7 cells (IC50 = 12.2 ± 1.2 µM).

Highlights

N-heterocyclic carbenes (NHCs) are nucleophilic compounds widely studied for their strong coordination ability as ancillary ligands of transition metals (M-NHCs) [1]
NHC-Ag complexes have been tested in reactions of diboration of alkenes [17], in the 1,3-dipolar cycloadditions of azomethine ylides with prop-2-enoates [18], in the cyclopropanation reactions between styrene and phenyldiazoacetate [19] and in the Sonogashira coupling of phenylacetylene and 4-iodoacetophenone [20]
We report the synthesis, characterization, and catalytic, antimicrobial, and antitumoral activities of new NHC silver(I) and gold(I) complexes (3a-b, 4a-b)

Summary

Introduction

N-heterocyclic carbenes (NHCs) are nucleophilic compounds widely studied for their strong coordination ability as ancillary ligands of transition metals (M-NHCs) [1] Their properties (steric and electronic) can be modulated, varying the substituents on the backbone and/or on the nitrogen atoms within the cyclic structure [1,2]. Among the many transition elements stabilized by these ligands, coinage metals play an important role They have proved to be useful activators in homogeneous catalysis for the hydrofunctionalization of allenes [9], alkenes [10] and alkynes [11], cycloisomerisations of enynes and ynones [12], C–H activation [13], and other organic transformations [14], as well as carbene transfer reactions [15]. NHC-Ag complexes have been tested in reactions of diboration of alkenes [17], in the 1,3-dipolar cycloadditions of azomethine ylides with prop-2-enoates [18], in the cyclopropanation reactions between styrene and phenyldiazoacetate [19] and in the Sonogashira coupling of phenylacetylene and 4-iodoacetophenone [20]

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