New Pyrazole-Hydrazone Derivatives: X-ray Analysis, Molecular Structure Investigation via Density Functional Theory (DFT) and Their High In-Situ Catecholase Activity.

Khalid Karrouchi,M’Hammed Ansar,Jamal Taoufik,Hazem Ghabbour,Younes Ouzidan,El Yousfi,Yahia Mabkhot,Youssef Ramli,Nada Sebbar,Smaail Radi

doi:10.3390/ijms18112215

Abstract

The development of low-cost catalytic systems that mimic the activity of tyrosinase enzymes (Catechol oxidase) is of great promise for future biochemistry technologic demands. Herein, we report the synthesis of new biomolecules systems based on hydrazone derivatives containing a pyrazole moiety (L1–L6) with superior catecholase activity. Crystal structures of L1 and L2 biomolecules were determined by X-ray single crystal diffraction (XRD). Optimized geometrical parameters were calculated by density functional theory (DFT) at B3LYP/6–31G (d, p) level and were found to be in good agreement with single crystal XRD data. Copper (II) complexes of the compounds (L1–L6), generated in-situ, were investigated for their catalytic activities towards the oxidation reaction of catechol to ortho-quinone with the atmospheric dioxygen, in an attempt to model the activity of the copper containing enzyme tyrosinase. The studies showed that the activities depend on four parameters: the nature of the ligand, the nature of counter anion, the nature of solvent and the concentration of ligand. The Cu(II)-ligands, given here, present the highest catalytic activity (72.920 μmol·L−1·min−1) among the catalysts recently reported in the existing literature.

Highlights

Bioorganometallic compounds are reputed for their remarkable applications in the field of catalysis; much less is known about their potential in chemical biology [1,2]
An important goal in organometallic chemistry is the synthesis of biomolecules that exhibit catalytic activity analogous to the activity of enzymes
We report the synthesis of six new hydrazone derivatives containing pyrazole moiety with a good yield (Scheme 1)

Summary

Introduction

Bioorganometallic compounds are reputed for their remarkable applications in the field of catalysis; much less is known about their potential in chemical biology [1,2]. An important goal in organometallic chemistry is the synthesis of biomolecules that exhibit catalytic activity analogous to the activity of enzymes. A number of catalysts having biomimetic activity for different enzymes have been designed by chemists [3,4]. The preparation and etude of efficient template complexes for metalloenzymes with oxidase or oxygenase activity are most important for the elaboration of new veritable catalysts for oxidation reactions [5]. As centers of potent site of various metalloproteins, play an essential role in several biological processes: electron transfer, oxidation, transport of dioxygen, etc. Copper complexes of low molecular weight are studied as structural and functional models of active centers of enzymes with copper [8,9,10,11]

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Conclusion