New benzothiazole based copper(II) hydrazone Schiff base complexes for selective and environmentally friendly oxidation of benzylic alcohols: The importance of the bimetallic species tuned by the choice of the counterion

Aleksandra Bocian , Adam Gorczyński , Damian Marcinkowski , Samanta Witomska , Maciej Kubicki , Paulina Mech , Małgorzata Bogunia , Jakub Brzeski , Mariusz Makowski , Piotr Pawluć , Violetta Patroniak

Abstract

Green and sustainable chemistryapproaches necessitate anongoing investigation towards new, environmentallybenign and selective catalysts. We have thus prepared a new benzothiazole-scaffolded hydrazone Schiff base ligand L and coordinated it with copper(II) ions leading tofive different complexes, the form of which in the solidstate is counterion-dependent. Nitrate, chloride and triflate anions lead to monometallic species, whereas utilization of sulfates and tetrafluoroborates is responsible for the formation of bimetallic assemblies. The catalytic efficiency of synthesized compounds was shown in Cu-TEMPO (2,2,6,6-tetramethyl-l-piperidinoxyl) aerobicoxidation of activated alcohols resulting in good to excellent conversions and 100% selectivity to form the corresponding aldehydes. Considering the experimental results and Density Functional Theory calculations we propose two most plausible reaction mechanisms that further corroborate the enhanced activity of bimetallicspecies. It appears that the tridentate character of the ligand sacrifices some of the overall catalytic efficiencyfor the selectivity of the process. Aqueous reaction medium, low catalyst loading, air as oxidant and exclusive oxidative selectivity render these CuII complexes promising candidates for further improvement.
Author Aleksandra Bocian
Aleksandra Bocian,,
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, Adam Gorczyński
Adam Gorczyński,,
-
, Damian Marcinkowski
Damian Marcinkowski,,
-
, Samanta Witomska
Samanta Witomska,,
-
, Maciej Kubicki
Maciej Kubicki,,
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, Paulina Mech (FCh / KChBionieorg. / LII)
Paulina Mech,,
- Laboratory of Intermolecular Interactions
, Małgorzata Bogunia (FCh / KChBionieorg. / LII)
Małgorzata Bogunia ,,
- Laboratory of Intermolecular Interactions
, Jakub Brzeski (FCh / KChBionieorg. / LII)
Jakub Brzeski,,
- Laboratory of Intermolecular Interactions
, Mariusz Makowski (FCh / KChBionieorg. / LII)
Mariusz Makowski,,
- Laboratory of Intermolecular Interactions
, Piotr Pawluć
Piotr Pawluć,,
-
et al.`
Journal seriesJournal of Molecular Liquids, ISSN 0167-7322, e-ISSN 1873-3166, (N/A 100 pkt)
Issue year2020
Vol302
Pages1-9
Publication size in sheets0.5
Article number112590
Keywords in Englishcopper, coordination compounds, complexes, Schiff base, hydrazone, alcohol oxidation, Density Functional Theory (DFT), green chemistry, environmental chemistry
ASJC Classification1606 Physical and Theoretical Chemistry; 1607 Spectroscopy; 2504 Electronic, Optical and Magnetic Materials; 2505 Materials Chemistry; 3104 Condensed Matter Physics; 3107 Atomic and Molecular Physics, and Optics
DOIDOI:10.1016/j.molliq.2020.112590
URL https://doi.org/10.1016/j.molliq.2020.112590
Languageen angielski
Score (nominal)100
Score sourcejournalList
ScoreMinisterial score = 100.0, 28-02-2020, ArticleFromJournal
Publication indicators Scopus SNIP (Source Normalised Impact per Paper): 2018 = 1.275; WoS Impact Factor: 2018 = 4.561 (2) - 2018=4.136 (5)
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