Acid–Base Behaviour in the Absorption and Emission Spectra of Ruthenium(II) Complexes with Hydroxy‐Substituted Bipyridine and Phenanthroline Ligands

Yu, Fei; Shen, Chang; Zheng, Tao; Chu, Wing‐Kin; Xiang, Jing; Ko, Chi‐Chiu; Guo, Zhengqing; Lau, Tai‐Chu

doi:10.1002/ejic.201600460

Cited by 16 publications

(12 citation statements)

References 73 publications

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“…We report here and experimentally support the cooperating effect in the C–H cleavage of arenes of [2, 2′-bipyridin]-6(1 H )-one (bipy-6-OH), whose deprotonated form effectively brings about the C–H cleavage of an arene. This and related ligands have been used before in Ir- or Ru-catalyzed hydrogen-transfer reactions , and other applications and by Duan et al in oxidative Heck reactions of arenes, where they attribute the improvement in the catalysis to a different reason: the anionic nature of the deprotonated ligand that favors the dissociation of an acetate . Monodentate pyridone derivatives have also been recently used to accelerate coupling reactions of arenes .…”

mentioning

confidence: 99%

[2,2′-Bipyridin]-6(1H)-one, a Truly Cooperating Ligand in the Palladium-Mediated C–H Activation Step: Experimental Evidence in the Direct C-3 Arylation of Pyridine

2018

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The ligand [2, 2'-bipyridin]-6(1H)-one (bipy-6-OH) has a strong accelerating effect in the Pd-catalyzed direct arylation of pyridine or arenes. The isolation of relevant intermediates and the study of their decomposition unequivocally show that the deprotonated coordinated ligand acts as a base and assists the cleavage of the C-H bond. Mechanistic work indicates that the direct arylation of pyridine with this ligand occurs through a Pd(0)/Pd(II) cycle. Because of this dual ligand-intramolecular base role, there is no need of an available coordination site on the metal for an external base, a difficulty encountered when chelating ligands are used in coupling reactions that involve a C-H cleavage step.

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mentioning

confidence: 99%

[2,2′-Bipyridin]-6(1H)-one, a Truly Cooperating Ligand in the Palladium-Mediated C–H Activation Step: Experimental Evidence in the Direct C-3 Arylation of Pyridine

2018

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“…Similar to most pH sensors, Ru(II) complex chemosensors for pH have mainly been developed through the mechanism of protonation and deprotonation of several functional groups, such as imidazole [ 106 , 107 ], hydroxyl (–OH) [ 108 – 110 ], carboxyl (–COOH) [ 111 ], pyridine [ 112 , 113 ] and others [ 114 ]. As a result of the protonation-deprotonation process, the molecular structures and the electron density distribution of Ru(II) complex are changed, leading to the variations of absorption and emission intensity/wavelength.…”

Section: Ru(ii) Complex Chemosensors For Phmentioning

confidence: 99%

Determination and Imaging of Small Biomolecules and Ions Using Ruthenium(II) Complex-Based Chemosensors

Zhang

Yong

et al. 2022

Top Curr Chem (Z)

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Luminescence chemosensors are one of the most useful tools for the determination and imaging of small biomolecules and ions in situ in real time. Based on the unique photo-physical/-chemical properties of ruthenium(II) (Ru(II)) complexes, the development of Ru(II) complex-based chemosensors has attracted increasing attention in recent years, and thus many Ru(II) complexes have been designed and synthesized for the detection of ions and small biomolecules in biological and environmental samples. In this work, we summarize the research advances in the development of Ru(II) complex-based chemosensors for the determination of ions and small biomolecules, including anions, metal ions, reactive biomolecules and amino acids, with a particular focus on binding/reaction-based chemosensors for the investigation of intracellular analytes’ evolution through luminescence analysis and imaging. The advances, challenges and future research directions in the development of Ru(II) complex-based chemosensors are also discussed.

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“…The complex shows a stronger emission at low pH and this was attributed to the reduction in the intramolecular reductive quenching effect from the lone-pair electrons of the oxygen atom, as the availability of the lone-pair of electrons for the electron-transfer process is reduced by protonation. 35 In addition, there is a significant decrease in the emission lifetime and quantum yields as the pH increases. A longer emission lifetime was observed in a low pH solution due to a deceleration in the thermally activated decay of the low-lying MLCT state to the short-lived metal centre state as a consequence of the stabilization of the MLCT and the destabilization of the metal-centred (MC) state.…”

Section: Experiments On Absorption and Luminescence Spectroscopymentioning

confidence: 99%

Augmented pH-sensitivity absorbance of a ruthenium(ii) bis(bipyridine) complex with elongation of the conjugated ligands: an experimental and theoretical investigation

Tan

Yanagisawa

Inagaki

et al. 2017

Phys. Chem. Chem. Phys.

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An absorbance-based sensor employing ruthenium bipyridyl with a phenanthroline-fused benzoylthiourea moiety formulated as [Ru(ii)(bpy)(phen-nBT)](PF) {bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline, nBT = n-benzoylthiourea} has been synthesized and characterized by elemental analyses, mass spectrometry, and infrared, ultraviolet-visible, luminescence and nuclear magnetic resonance spectroscopy. The changes in the intensity of absorption and emission of the complex induced by functionalization of the benzoylthiourea ligands with amino and carbonyl in their protonated and deprotonated forms were studied experimentally. The absorption and emission properties of the complex exhibit a strong dependence on the pH (1-11) of the aqueous medium. This work highlights the pH-sensitivity augmentation of the absorption band by elongating the conjugation length in the structure of the ruthenium bipyridine complex. The principle of this work was to design the title compound to be capable of enhancing the differences in the absorption sensitivity responses towards pH between the protonated and deprotonated complexes in the absorption measurement. Along with significant and noticeable changes in the absorption spectra, subsequent theoretical investigations specifically on the electronic and absorbance properties of the title compound were carried out in this study. Protonation of the molecule significantly stabilized the lowest-unoccupied molecular orbital (LUMO), whereas the highest-occupied molecular orbital (HOMO) is greatly destabilized upon deprotonation. A time-dependent density functional theory (TDDFT) calculation in the linear-response (-LR) regime was performed to clarify the origin of the experimentally observed linear dependence of absorption intensity upon pH (1-11). The MLCT band exhibits hyperchromic shift at low pH as indicated by the large transition dipole moment and a wider distribution of the response charge of the molecule, which is induced by the stabilization of the electrostatic potential at the carbonyl moiety by protonation. This study provides the possibility of employing theoretical information to gain insight into the origin of the optical absorption obtained experimentally. The ruthenium complex was designed with an elongated ligand conjugation length and exhibited a tremendously large change in the absorption intensity of the protonated and deprotonated forms, which therefore demonstrates its feasibility as an indicator molecule especially for absorbance measurements.

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Acid–Base Behaviour in the Absorption and Emission Spectra of Ruthenium(II) Complexes with Hydroxy‐Substituted Bipyridine and Phenanthroline Ligands

Cited by 16 publications

References 73 publications

[2,2′-Bipyridin]-6(1H)-one, a Truly Cooperating Ligand in the Palladium-Mediated C–H Activation Step: Experimental Evidence in the Direct C-3 Arylation of Pyridine

[2,2′-Bipyridin]-6(1H)-one, a Truly Cooperating Ligand in the Palladium-Mediated C–H Activation Step: Experimental Evidence in the Direct C-3 Arylation of Pyridine

Determination and Imaging of Small Biomolecules and Ions Using Ruthenium(II) Complex-Based Chemosensors

Augmented pH-sensitivity absorbance of a ruthenium(ii) bis(bipyridine) complex with elongation of the conjugated ligands: an experimental and theoretical investigation

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