THE STUDY OF LIGAND EXCHANGE REACTIONS IN THE MIXED-LIGAND HAFNIUM PHTHALO-CYANINE COMPLEX BY 1H NMR SPECTROSCOPY

The reactivity of a mixed-ligand alkylamino-β-ketoenolato decanoatophthalocyaninate of hafnium was investigated by 1H NMR spectroscopy via substitution of axial ligands in reactions with para-isopropoxybenzoic acid and dibenzoylmethane. The initial complex PcHf(C₉H₁₉COO)L was shown to exhibit high r...

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Date:2026
Main Authors: Tretyakova, Iryna, Fedosova, Natalia, Dovbiy, Yan, Chernii, Viktor
Format: Article
Language:English
Published: V.I.Vernadsky Institute of General and Inorganic Chemistry 2026
Online Access:https://ucj.org.ua/index.php/journal/article/view/771
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Journal Title:Ukrainian Chemistry Journal

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Ukrainian Chemistry Journal
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author Tretyakova, Iryna
Fedosova, Natalia
Dovbiy, Yan
Chernii, Viktor
author_facet Tretyakova, Iryna
Fedosova, Natalia
Dovbiy, Yan
Chernii, Viktor
author_sort Tretyakova, Iryna
baseUrl_str https://ucj.org.ua/index.php/journal/oai
collection OJS
datestamp_date 2026-05-01T10:54:33Z
description The reactivity of a mixed-ligand alkylamino-β-ketoenolato decanoatophthalocyaninate of hafnium was investigated by 1H NMR spectroscopy via substitution of axial ligands in reactions with para-isopropoxybenzoic acid and dibenzoylmethane. The initial complex PcHf(C₉H₁₉COO)L was shown to exhibit high reactivity. It was established that the presence of different axial ligands enables their selective or complete substitution depending on the nature of the reagent. In the reaction with  para-isopropoxybenzoic acid, only the decanoate ligand is replaced, leading to the formation of a new mixed-ligand complex  PcHf(C₁₀H₁₁O₃)L. The 1H NMR spectrum of the obtained complex displays signals of the phthalocyanine macrocycle protons (9.5–8.1 ppm) and the para-substituted benzoate fragment (7.5–7.4 ppm). Signals corresponding to the alkylamino-β-ketoenol ligand are observed in the region 7.2–5.5 ppm, as well as in the aliphatic region. The absence of signals corresponding to the decanoate chain protons (0.0–0.5 ppm) and the appearance of signals of the isopropyl methyl protons (2.27 ppm) confirm the completion of the ligand exchange reaction. In contrast, the reaction of PcHf(C₉H₁₉COO)L with dibenzoylmethane results in complete substitution of both axial ligands (decanoate and alkylamino-β-keto­enolate), yielding bis(dibenzoylmethanato)hafnium phthalocyaninate. The 1H NMR spectrum of the product shows no signals of either decanoate or alkylamino-β-ketoenolate protons and matches the previously repor­ted spectrum of PcHf(dbm)₂. A stability series of chelate rings in the coordination sphere of hafnium phthalocyaninates was established. The strength of ligand binding to the central metal atom increases in the following order: aliphatic carboxylate < aromatic carboxylate < alkylamino-β-ketoenolate < β-diketonate.  The obtained results expand the possibilities for the targeted synthesis of out-of-plane coordinated phthalocyanine complexes, enabling the tuning of their physicochemical properties (such as solubility and spectral characteristics) for potential applications in photodynamic therapy, organic semiconductors, and sensors.
doi_str_mv 10.33609/2708-129X.92.3.2026.18-26
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spelling oai:ojs2.1444248.nisspano.web.hosting-test.net:article-7712026-05-01T10:54:33Z THE STUDY OF LIGAND EXCHANGE REACTIONS IN THE MIXED-LIGAND HAFNIUM PHTHALO-CYANINE COMPLEX BY 1H NMR SPECTROSCOPY Tretyakova, Iryna Fedosova, Natalia Dovbiy, Yan Chernii, Viktor phthalocyanine, hafnium, ligand exchange, 1H NMR spectroscopy, mixed ligand complexes. The reactivity of a mixed-ligand alkylamino-β-ketoenolato decanoatophthalocyaninate of hafnium was investigated by 1H NMR spectroscopy via substitution of axial ligands in reactions with para-isopropoxybenzoic acid and dibenzoylmethane. The initial complex PcHf(C₉H₁₉COO)L was shown to exhibit high reactivity. It was established that the presence of different axial ligands enables their selective or complete substitution depending on the nature of the reagent. In the reaction with  para-isopropoxybenzoic acid, only the decanoate ligand is replaced, leading to the formation of a new mixed-ligand complex  PcHf(C₁₀H₁₁O₃)L. The 1H NMR spectrum of the obtained complex displays signals of the phthalocyanine macrocycle protons (9.5–8.1 ppm) and the para-substituted benzoate fragment (7.5–7.4 ppm). Signals corresponding to the alkylamino-β-ketoenol ligand are observed in the region 7.2–5.5 ppm, as well as in the aliphatic region. The absence of signals corresponding to the decanoate chain protons (0.0–0.5 ppm) and the appearance of signals of the isopropyl methyl protons (2.27 ppm) confirm the completion of the ligand exchange reaction. In contrast, the reaction of PcHf(C₉H₁₉COO)L with dibenzoylmethane results in complete substitution of both axial ligands (decanoate and alkylamino-β-keto­enolate), yielding bis(dibenzoylmethanato)hafnium phthalocyaninate. The 1H NMR spectrum of the product shows no signals of either decanoate or alkylamino-β-ketoenolate protons and matches the previously repor­ted spectrum of PcHf(dbm)₂. A stability series of chelate rings in the coordination sphere of hafnium phthalocyaninates was established. The strength of ligand binding to the central metal atom increases in the following order: aliphatic carboxylate < aromatic carboxylate < alkylamino-β-ketoenolate < β-diketonate.  The obtained results expand the possibilities for the targeted synthesis of out-of-plane coordinated phthalocyanine complexes, enabling the tuning of their physicochemical properties (such as solubility and spectral characteristics) for potential applications in photodynamic therapy, organic semiconductors, and sensors. V.I.Vernadsky Institute of General and Inorganic Chemistry 2026-04-30 Article Article Inorganic Chemistry Неорганическая химия Неорганічна хімія application/pdf https://ucj.org.ua/index.php/journal/article/view/771 10.33609/2708-129X.92.3.2026.18-26 Ukrainian Chemistry Journal; Vol. 92 No. 3 (2026): Ukrainian Chemistry Journal; 18-26 Украинский химический журнал; Том 92 № 3 (2026): Ukrainian Chemistry Journal; 18-26 Український хімічний журнал; Том 92 № 3 (2026): Ukrainian Chemistry Journal; 18-26 2708-129X 2708-1281 en https://ucj.org.ua/index.php/journal/article/view/771/404
spellingShingle Tretyakova, Iryna
Fedosova, Natalia
Dovbiy, Yan
Chernii, Viktor
THE STUDY OF LIGAND EXCHANGE REACTIONS IN THE MIXED-LIGAND HAFNIUM PHTHALO-CYANINE COMPLEX BY 1H NMR SPECTROSCOPY
title THE STUDY OF LIGAND EXCHANGE REACTIONS IN THE MIXED-LIGAND HAFNIUM PHTHALO-CYANINE COMPLEX BY 1H NMR SPECTROSCOPY
title_full THE STUDY OF LIGAND EXCHANGE REACTIONS IN THE MIXED-LIGAND HAFNIUM PHTHALO-CYANINE COMPLEX BY 1H NMR SPECTROSCOPY
title_fullStr THE STUDY OF LIGAND EXCHANGE REACTIONS IN THE MIXED-LIGAND HAFNIUM PHTHALO-CYANINE COMPLEX BY 1H NMR SPECTROSCOPY
title_full_unstemmed THE STUDY OF LIGAND EXCHANGE REACTIONS IN THE MIXED-LIGAND HAFNIUM PHTHALO-CYANINE COMPLEX BY 1H NMR SPECTROSCOPY
title_short THE STUDY OF LIGAND EXCHANGE REACTIONS IN THE MIXED-LIGAND HAFNIUM PHTHALO-CYANINE COMPLEX BY 1H NMR SPECTROSCOPY
title_sort study of ligand exchange reactions in the mixed-ligand hafnium phthalo-cyanine complex by 1h nmr spectroscopy
topic_facet phthalocyanine
hafnium
ligand exchange
1H NMR spectroscopy
mixed ligand complexes.
url https://ucj.org.ua/index.php/journal/article/view/771
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