AUTHOR=Sutradhar Manas , Alegria Elisabete C. B. A. , Barman Tannistha Roy , Guedes da Silva M. Fátima C. , Liu Cai-Ming , Pombeiro Armando J. L. 

TITLE=1D Copper(II)-Aroylhydrazone Coordination Polymers: Magnetic Properties and Microwave Assisted Oxidation of a Secondary Alcohol

JOURNAL=Frontiers in Chemistry

VOLUME=8

YEAR=2020

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2020.00157

DOI=10.3389/fchem.2020.00157

ISSN=2296-2646

ABSTRACT=<p>The 1D Cu(II) coordination polymers [Cu<sub>3</sub>(L<sup>1</sup>)(NO<sub>3</sub>)<sub>4</sub>(H<sub>2</sub>O)<sub>2</sub>]<sub>n</sub> (<bold>1</bold>) and [Cu<sub>2</sub>(H<sub>2</sub>L<sup>2</sup>)(NO<sub>3</sub>)(H<sub>2</sub>O)<sub>2</sub>]<sub>n</sub>(NO<sub>3</sub>)<sub>n</sub> (<bold>2</bold>) have been synthesized using the aroylhyrazone Schiff bases <italic>N'</italic><sup>1</sup>,<italic>N'</italic><sup>2</sup>-bis(pyridin-2-ylmethylene)oxalohydrazide (H<sub>2</sub>L<sup>1</sup>) and <italic>N'</italic><sup>1</sup>,<italic>N'</italic><sup>3</sup>-bis(2-hydroxybenzylidene)malonohydrazide (H<sub>4</sub>L<sup>2</sup>), respectively. They have been characterized by elemental analysis, infrared (IR) spectroscopy, UV-Vis spectroscopy, electrospray ionization mass spectrometry (ESI-MS), single crystal X-ray diffraction and variable temperature magnetic susceptibility measurements (for <bold>2</bold>). The ligand (L<sup>1</sup>)<sup>2−</sup> coordinates in the <italic>iminol</italic> form in <bold>1</bold>, whereas the <italic>amide</italic> coordination is observed for (H<sub>2</sub>L<sup>2</sup>)<sup>2−</sup> in <bold>2</bold>. Either the ligand bridge or the nitrate bridge in <bold>2</bold> mediates weak antiferromagnetic coupling. The catalytic performance of <bold>1</bold> and <bold>2</bold> has been investigated toward the solvent-free microwave-assisted oxidation of a secondary alcohol (1-phenylethanol used as model substrate). At 120°C and in the presence of the nitroxyl radical 2,2,6,6-tetramethylpiperydil-1-oxyl (TEMPO), the complete conversion of 1-phenylethanol into acetophenone occurs with TOFs up to 1,200 h<sup>−1</sup>.</p>