Riassunto analitico
Schiff bases have been known for over a Century. Hugo Schiff first reported their synthesis in 1864 via condensation between an aldehyde and a primary amine. The so-obtained imine fragments, of general formula R1R2C=NR3, can be inserted into an organic molecular skeleton containing other donor atoms, generating compounds that can act as oligodentate ligands towards transition metals. One of the most famous tetradentate Schiff bases is H2salen, derived from the condensation of two salicylaldehyde (Hsal) molecules with ethylenediamine (en), and its complexation to almost all metal ions of the Periodic Table has been reported. These types of compounds have a very wide range of applications, such as optics, magnetism and, especially, catalysis. This Thesis work focused on the synthesis of “salben” ligands, analogous to the “salen” derivatives, where the ethylene bridge between the two imine groups is replaced by a phenyl-methylene one. The respective copper(II) complexes were synthesised and their catalytic performances were tested, with the aim of understanding the modulating effect of the different substituents on the aryl rings. The identity of the synthesised ligands and copper(II) catalysts was confirmed by different analytical techniques such as 1H and 13C NMR spectroscopy, IR spectroscopy, elemental analysis and mass spectrometry.
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Abstract
Schiff bases have been known for over a Century. Hugo Schiff first reported their synthesis in 1864 via condensation between an aldehyde and a primary amine. The so-obtained imine fragments, of general formula R1R2C=NR3, can be inserted into an organic molecular skeleton containing other donor atoms, generating compounds that can act as oligodentate ligands towards transition metals. One of the most famous tetradentate Schiff bases is H2salen, derived from the condensation of two salicylaldehyde (Hsal) molecules with ethylenediamine (en), and its complexation to almost all metal ions of the Periodic Table has been reported. These types of compounds have a very wide range of applications, such as optics, magnetism and, especially, catalysis. This Thesis work focused on the synthesis of “salben” ligands, analogous to the “salen” derivatives, where the ethylene bridge between the two imine groups is replaced by a phenyl-methylene one. The respective copper(II) complexes were synthesised and their catalytic performances were tested, with the aim of understanding the modulating effect of the different substituents on the aryl rings. The identity of the synthesised ligands and copper(II) catalysts was confirmed by different analytical techniques such as 1H and 13C NMR spectroscopy, IR spectroscopy, elemental analysis and mass spectrometry.
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