Dovbii Y. Synthesis, structure, and properties of phthalocyanine complexes of zirconium (IV) and hafnium (IV) with out-of-plane coordinated β-ketoenol chromophore ligands

This work aims to develop functionalization methods of zirconium and hafnium phthalocyanine complexes by a ligand exchange reaction between dicarboxylatophthalocyaninates of these metals and β-ketoenols, condensed from aldehydes derivatives of dehydroacetic acid (DHA), N-alkyl-ketoenols, and curcumin. A series of chromophoric ligand chalcones containing various functional substituents were obtained by an optimized method of Knevenagel reaction with DHA and substituted aldehydes. Their interaction with primary alkylamines, the products of which are N-alkylamino-β-ketoenols, was studied. It was shown that the substituents in compounds are located in the trans-position to the β-ketoenol fragment of dehydroacetic acid that was proved by X-ray diffraction. 1H NMR spectra revealed that N-alkylamino-N-ketoenols in solutions are in the form of tautomeric isomers. According to the optimized synthesis method, several previously undescribed ligands containing amino- and -ketoenol fragment with a chromophoric polymethine chain were obtained. It was shown that the different structure of ligands (denticity and the presence of coordination centers) leads to the formation of different out-of-plane coordinated complexes. Their structure has been established by 1H NMR and mass spectrometry. Complexes obtained from 8-oxyquinoline and dehydroacetic acid contain two identical appropriate ligands placed in the cis- or trans-position to each other due to the asymmetry of their structure. For complexes of the composition PcM(curc)2, such isomerism is not typical. It was found that starting from N-alkylamino-β-ketoenols and Zr or Hf dicarboxylate phthalocyaninates, complexes with only one chromophore ligand and a carboxylate fragment could be obtained, which could not be additionally substituted. Mixed-ligand phthalocyanines complexes of zirconium and hafnium were obtained for the first time with several condensed DHA derivatives. Their molecules contain an N-alkylamino-β-ketoenol ligand and a carboxylate ligand, which could not be substitute in the original dicarboxylatophthalocyaninates. Data on the chemical composition, electronic and spatial structure of the synthesized compounds were obtained by elemental analysis, 1H NMR spectroscopy, IR spectroscopy, UV-Vis spectroscopy, mass spectrometry, fluorescence spectroscopy, and X-ray diffraction analysis. The effect of chromophore ligands on the spectral characteristics of the obtained complexes was shown.