Axial Ligand Effects on the Mechanism of Ru-CO Bond Photodissociation and Photophysical Properties of Ru(II)-Salen PhotoCORMs/Theranostics: A Density Functional Theory Study

Density functional theory (DFT) calculations were employed to study a series of complexes of general formula [Ru(salen)(X)(CO)]<sup>0/−1</sup> (X = Cl<sup>−</sup>, F<sup>−</sup>, SCN<sup>−</sup>, DMSO, Phosphabenzene, Phosphole, TPH, CN<sup>−<...

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Main Authors: Niq Catevas, Athanassios Tsipis
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Molecules
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Online Access:https://www.mdpi.com/1420-3049/30/5/1147
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author Niq Catevas
Athanassios Tsipis
author_facet Niq Catevas
Athanassios Tsipis
author_sort Niq Catevas
collection DOAJ
description Density functional theory (DFT) calculations were employed to study a series of complexes of general formula [Ru(salen)(X)(CO)]<sup>0/−1</sup> (X = Cl<sup>−</sup>, F<sup>−</sup>, SCN<sup>−</sup>, DMSO, Phosphabenzene, Phosphole, TPH, CN<sup>−</sup>, N<sub>3</sub><sup>−</sup>, NO<sub>3</sub><sup>−</sup>, CNH<sup>−</sup>, NHC, P(OH)<sub>3</sub>, PF<sub>3</sub>, PH<sub>3</sub>). The effect of ligands X on the Ru-CO bond was quantified by the <i>trans</i>-philicity, Δ<i>σ</i><sup>13</sup>C NMR parameter. The potential of Δ<i>σ</i><sup>13</sup>C to be used as a probe of the CO photodissociation by Ru(II) transition metal complexes is established upon comparing it with other <i>trans</i>-effect parameters. An excellent linear correlation is found between the energy barrier for the Ru-CO photodissociation and the Δ<i>σ</i><sup>13</sup>C parameter, paving the way for studying photoCORMs with the <sup>13</sup>C NMR method. The strongest <i>trans</i>-effect on the Ru-CO bond in the [Ru(salen)(X)(CO)]<sup>0/−1</sup> complexes are found when X = CNH<sup>−</sup>, NHC, and P(OH)<sub>3</sub>, while the weakest for X = Cl<sup>−</sup>, NO<sub>3</sub><sup>−</sup> and DMSO <i>trans</i>-axial ligands. The Ru-CO bonding properties were scrutinized using Natural Bond Orbital (NBO), Natural Energy Decomposition Analysis (NEDA) and Natural Orbital of Chemical Valence (NOCV) methods. The nature of the Ru-CO bond is composite, i.e., electrostatic, covalent and charge transfer. Both donation and backdonation between CO ligand and Ru metal centre equally stabilize the Ru(II) complexes. Ru-CO photodissociation proceeds via a <sup>3</sup>MC triplet excited state, exhibiting a conical intersection with the T<sub>1</sub> <sup>3</sup>MLCT excited state. Calculations show that these complexes show bands within visible while they are expected to be red emitters. Therefore, the [Ru(salen)(X)(CO)]<sup>0/−1</sup> complexes under study could potentially be used for dual action, photoCORMs and theranostics compounds.
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spelling doaj-art-95a7f46181bc48d6914da8b378dc6f112025-08-20T02:59:00ZengMDPI AGMolecules1420-30492025-03-01305114710.3390/molecules30051147Axial Ligand Effects on the Mechanism of Ru-CO Bond Photodissociation and Photophysical Properties of Ru(II)-Salen PhotoCORMs/Theranostics: A Density Functional Theory StudyNiq Catevas0Athanassios Tsipis1Laboratory of Inorganic Chemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, GreeceLaboratory of Inorganic Chemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, GreeceDensity functional theory (DFT) calculations were employed to study a series of complexes of general formula [Ru(salen)(X)(CO)]<sup>0/−1</sup> (X = Cl<sup>−</sup>, F<sup>−</sup>, SCN<sup>−</sup>, DMSO, Phosphabenzene, Phosphole, TPH, CN<sup>−</sup>, N<sub>3</sub><sup>−</sup>, NO<sub>3</sub><sup>−</sup>, CNH<sup>−</sup>, NHC, P(OH)<sub>3</sub>, PF<sub>3</sub>, PH<sub>3</sub>). The effect of ligands X on the Ru-CO bond was quantified by the <i>trans</i>-philicity, Δ<i>σ</i><sup>13</sup>C NMR parameter. The potential of Δ<i>σ</i><sup>13</sup>C to be used as a probe of the CO photodissociation by Ru(II) transition metal complexes is established upon comparing it with other <i>trans</i>-effect parameters. An excellent linear correlation is found between the energy barrier for the Ru-CO photodissociation and the Δ<i>σ</i><sup>13</sup>C parameter, paving the way for studying photoCORMs with the <sup>13</sup>C NMR method. The strongest <i>trans</i>-effect on the Ru-CO bond in the [Ru(salen)(X)(CO)]<sup>0/−1</sup> complexes are found when X = CNH<sup>−</sup>, NHC, and P(OH)<sub>3</sub>, while the weakest for X = Cl<sup>−</sup>, NO<sub>3</sub><sup>−</sup> and DMSO <i>trans</i>-axial ligands. The Ru-CO bonding properties were scrutinized using Natural Bond Orbital (NBO), Natural Energy Decomposition Analysis (NEDA) and Natural Orbital of Chemical Valence (NOCV) methods. The nature of the Ru-CO bond is composite, i.e., electrostatic, covalent and charge transfer. Both donation and backdonation between CO ligand and Ru metal centre equally stabilize the Ru(II) complexes. Ru-CO photodissociation proceeds via a <sup>3</sup>MC triplet excited state, exhibiting a conical intersection with the T<sub>1</sub> <sup>3</sup>MLCT excited state. Calculations show that these complexes show bands within visible while they are expected to be red emitters. Therefore, the [Ru(salen)(X)(CO)]<sup>0/−1</sup> complexes under study could potentially be used for dual action, photoCORMs and theranostics compounds.https://www.mdpi.com/1420-3049/30/5/1147photoCORMstheranostics<i>trans</i>-philicityRu(II) salen complexesRu-CO bond photodissociation
spellingShingle Niq Catevas
Athanassios Tsipis
Axial Ligand Effects on the Mechanism of Ru-CO Bond Photodissociation and Photophysical Properties of Ru(II)-Salen PhotoCORMs/Theranostics: A Density Functional Theory Study
Molecules
photoCORMs
theranostics
<i>trans</i>-philicity
Ru(II) salen complexes
Ru-CO bond photodissociation
title Axial Ligand Effects on the Mechanism of Ru-CO Bond Photodissociation and Photophysical Properties of Ru(II)-Salen PhotoCORMs/Theranostics: A Density Functional Theory Study
title_full Axial Ligand Effects on the Mechanism of Ru-CO Bond Photodissociation and Photophysical Properties of Ru(II)-Salen PhotoCORMs/Theranostics: A Density Functional Theory Study
title_fullStr Axial Ligand Effects on the Mechanism of Ru-CO Bond Photodissociation and Photophysical Properties of Ru(II)-Salen PhotoCORMs/Theranostics: A Density Functional Theory Study
title_full_unstemmed Axial Ligand Effects on the Mechanism of Ru-CO Bond Photodissociation and Photophysical Properties of Ru(II)-Salen PhotoCORMs/Theranostics: A Density Functional Theory Study
title_short Axial Ligand Effects on the Mechanism of Ru-CO Bond Photodissociation and Photophysical Properties of Ru(II)-Salen PhotoCORMs/Theranostics: A Density Functional Theory Study
title_sort axial ligand effects on the mechanism of ru co bond photodissociation and photophysical properties of ru ii salen photocorms theranostics a density functional theory study
topic photoCORMs
theranostics
<i>trans</i>-philicity
Ru(II) salen complexes
Ru-CO bond photodissociation
url https://www.mdpi.com/1420-3049/30/5/1147
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