Mononuclear and Dinuclear Complexes of Dibenzoeilatin: Synthesis, Structure, and Electrochemical and Photophysical Properties

Sheba D. Bergman; Israel Goldberg; Andrea Barbieri; Francesco Barigelletti; Moshe Kol

doi:10.1021/ic0354062

Mononuclear and Dinuclear Complexes of Dibenzoeilatin: Synthesis, Structure, and Electrochemical and Photophysical Properties

Sheba D. Bergman
, Israel Goldberg
, Andrea Barbieri
, Francesco Barigelletti^*
, Moshe Kol

^*Corresponding author for this work

School of Chemistry

Tel Aviv University
National Research Council of Italy

Research output: Contribution to journal › Article › peer-review

51 Scopus citations

Abstract

This work describes a study of Ru(II) and Os(II) polypyridyl complexes of the symmetrical, fused-aromatic bridging ligand dibenzoeilatin (1). The synthesis, purification, and structural characterization by NMR of the mononuclear complexes [Ru(bpy)₂(dbneil)]²⁺ (2), [Ru(tmbpy)₂(dbneil)]²⁺ (3), and [Os(bpy) ₂(dbneil)]²⁺ (4), the homodinuclear complexes [{Ru(bpy)₂}₂{μ-dbneil}]⁴⁺ (5), [{Ru(tmbpy)₂}₂{μ-dbneil}]⁴⁺ (6), and [{Os(bpy)₂}₂{μ-dbneil}]⁴⁺ (7), and the heterodinuclear complex [{Ru(bpy)₂}{μ-dbneil}{Os(bpy) ₂}]⁴⁺ (8) are described, along with the crystal structures of 4, 6, and 7. Absorption spectra of the mononuclear complexes feature a low-lying MLCT band around 600 nm. The coordination of a second metal fragment results in a dramatic red shift of the MLCT band to beyond 700 nm. Cyclic and square wave voltammograms of the mononuclear complexes exhibit one reversible metal-based oxidation, as well as several ligand-based reduction waves. The first two reductions, attributed to reduction of the dibenzoeilatin ligand, are substantially anodically shifted compared to [M(bpy) ₃]²⁺ (M = Ru, Os), consistent with the low-lying π* orbital of dibenzoeilatin. The dinuclear complexes exhibit two reversible, well-resolved, metal-centered oxidation waves, despite the chemical equivalence of the two metal centers, indicating a significant metal-metal interaction mediated by the conjugated dibenzoeilatin ligand, Luminescence spectra, quantum yield, and lifetime measurements at room temperature in argon-purged acetonitrile have shown that the complexes exhibit ³MLCT emission, which occurs in the IR-region between 950 and 1300 nm. The heterodinuclear complex 8 exhibits luminescence only from the Ru-based fragment, the intensity of which is less than 1% of that observed in the corresponding homodinuclear complex 5; no emission from the Os-based unit is observed, and an intramolecular quenching constant of k_q ≥ 3 × 10⁹ S^-1 is evaluated. The nature of the quenching process is briefly discussed.

Original language	English
Pages (from-to)	2355-2367
Number of pages	13
Journal	Inorganic Chemistry
Volume	43
Issue number	7
DOIs	https://doi.org/10.1021/ic0354062
State	Published - 5 Apr 2004

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@article{e02dec18887b4c669aa55aee7b9d4ae0,

title = "Mononuclear and Dinuclear Complexes of Dibenzoeilatin: Synthesis, Structure, and Electrochemical and Photophysical Properties",

abstract = "This work describes a study of Ru(II) and Os(II) polypyridyl complexes of the symmetrical, fused-aromatic bridging ligand dibenzoeilatin (1). The synthesis, purification, and structural characterization by NMR of the mononuclear complexes [Ru(bpy)2(dbneil)]2+ (2), [Ru(tmbpy)2(dbneil)]2+ (3), and [Os(bpy) 2(dbneil)]2+ (4), the homodinuclear complexes [\{Ru(bpy)2\}2\{μ-dbneil\}]4+ (5), [\{Ru(tmbpy)2\}2\{μ-dbneil\}]4+ (6), and [\{Os(bpy)2\}2\{μ-dbneil\}]4+ (7), and the heterodinuclear complex [\{Ru(bpy)2\}\{μ-dbneil\}\{Os(bpy) 2\}]4+ (8) are described, along with the crystal structures of 4, 6, and 7. Absorption spectra of the mononuclear complexes feature a low-lying MLCT band around 600 nm. The coordination of a second metal fragment results in a dramatic red shift of the MLCT band to beyond 700 nm. Cyclic and square wave voltammograms of the mononuclear complexes exhibit one reversible metal-based oxidation, as well as several ligand-based reduction waves. The first two reductions, attributed to reduction of the dibenzoeilatin ligand, are substantially anodically shifted compared to [M(bpy) 3]2+ (M = Ru, Os), consistent with the low-lying π* orbital of dibenzoeilatin. The dinuclear complexes exhibit two reversible, well-resolved, metal-centered oxidation waves, despite the chemical equivalence of the two metal centers, indicating a significant metal-metal interaction mediated by the conjugated dibenzoeilatin ligand, Luminescence spectra, quantum yield, and lifetime measurements at room temperature in argon-purged acetonitrile have shown that the complexes exhibit 3MLCT emission, which occurs in the IR-region between 950 and 1300 nm. The heterodinuclear complex 8 exhibits luminescence only from the Ru-based fragment, the intensity of which is less than 1\% of that observed in the corresponding homodinuclear complex 5; no emission from the Os-based unit is observed, and an intramolecular quenching constant of kq ≥ 3 × 109 S-1 is evaluated. The nature of the quenching process is briefly discussed.",

author = "Bergman, \{Sheba D.\} and Israel Goldberg and Andrea Barbieri and Francesco Barigelletti and Moshe Kol",

year = "2004",

month = apr,

day = "5",

doi = "10.1021/ic0354062",

language = "אנגלית",

volume = "43",

pages = "2355--2367",

journal = "Inorganic Chemistry",

issn = "0020-1669",

publisher = "American Chemical Society",

number = "7",

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TY - JOUR

T1 - Mononuclear and Dinuclear Complexes of Dibenzoeilatin

T2 - Synthesis, Structure, and Electrochemical and Photophysical Properties

AU - Bergman, Sheba D.

AU - Goldberg, Israel

AU - Barbieri, Andrea

AU - Barigelletti, Francesco

AU - Kol, Moshe

PY - 2004/4/5

Y1 - 2004/4/5

N2 - This work describes a study of Ru(II) and Os(II) polypyridyl complexes of the symmetrical, fused-aromatic bridging ligand dibenzoeilatin (1). The synthesis, purification, and structural characterization by NMR of the mononuclear complexes [Ru(bpy)2(dbneil)]2+ (2), [Ru(tmbpy)2(dbneil)]2+ (3), and [Os(bpy) 2(dbneil)]2+ (4), the homodinuclear complexes [{Ru(bpy)2}2{μ-dbneil}]4+ (5), [{Ru(tmbpy)2}2{μ-dbneil}]4+ (6), and [{Os(bpy)2}2{μ-dbneil}]4+ (7), and the heterodinuclear complex [{Ru(bpy)2}{μ-dbneil}{Os(bpy) 2}]4+ (8) are described, along with the crystal structures of 4, 6, and 7. Absorption spectra of the mononuclear complexes feature a low-lying MLCT band around 600 nm. The coordination of a second metal fragment results in a dramatic red shift of the MLCT band to beyond 700 nm. Cyclic and square wave voltammograms of the mononuclear complexes exhibit one reversible metal-based oxidation, as well as several ligand-based reduction waves. The first two reductions, attributed to reduction of the dibenzoeilatin ligand, are substantially anodically shifted compared to [M(bpy) 3]2+ (M = Ru, Os), consistent with the low-lying π* orbital of dibenzoeilatin. The dinuclear complexes exhibit two reversible, well-resolved, metal-centered oxidation waves, despite the chemical equivalence of the two metal centers, indicating a significant metal-metal interaction mediated by the conjugated dibenzoeilatin ligand, Luminescence spectra, quantum yield, and lifetime measurements at room temperature in argon-purged acetonitrile have shown that the complexes exhibit 3MLCT emission, which occurs in the IR-region between 950 and 1300 nm. The heterodinuclear complex 8 exhibits luminescence only from the Ru-based fragment, the intensity of which is less than 1% of that observed in the corresponding homodinuclear complex 5; no emission from the Os-based unit is observed, and an intramolecular quenching constant of kq ≥ 3 × 109 S-1 is evaluated. The nature of the quenching process is briefly discussed.

AB - This work describes a study of Ru(II) and Os(II) polypyridyl complexes of the symmetrical, fused-aromatic bridging ligand dibenzoeilatin (1). The synthesis, purification, and structural characterization by NMR of the mononuclear complexes [Ru(bpy)2(dbneil)]2+ (2), [Ru(tmbpy)2(dbneil)]2+ (3), and [Os(bpy) 2(dbneil)]2+ (4), the homodinuclear complexes [{Ru(bpy)2}2{μ-dbneil}]4+ (5), [{Ru(tmbpy)2}2{μ-dbneil}]4+ (6), and [{Os(bpy)2}2{μ-dbneil}]4+ (7), and the heterodinuclear complex [{Ru(bpy)2}{μ-dbneil}{Os(bpy) 2}]4+ (8) are described, along with the crystal structures of 4, 6, and 7. Absorption spectra of the mononuclear complexes feature a low-lying MLCT band around 600 nm. The coordination of a second metal fragment results in a dramatic red shift of the MLCT band to beyond 700 nm. Cyclic and square wave voltammograms of the mononuclear complexes exhibit one reversible metal-based oxidation, as well as several ligand-based reduction waves. The first two reductions, attributed to reduction of the dibenzoeilatin ligand, are substantially anodically shifted compared to [M(bpy) 3]2+ (M = Ru, Os), consistent with the low-lying π* orbital of dibenzoeilatin. The dinuclear complexes exhibit two reversible, well-resolved, metal-centered oxidation waves, despite the chemical equivalence of the two metal centers, indicating a significant metal-metal interaction mediated by the conjugated dibenzoeilatin ligand, Luminescence spectra, quantum yield, and lifetime measurements at room temperature in argon-purged acetonitrile have shown that the complexes exhibit 3MLCT emission, which occurs in the IR-region between 950 and 1300 nm. The heterodinuclear complex 8 exhibits luminescence only from the Ru-based fragment, the intensity of which is less than 1% of that observed in the corresponding homodinuclear complex 5; no emission from the Os-based unit is observed, and an intramolecular quenching constant of kq ≥ 3 × 109 S-1 is evaluated. The nature of the quenching process is briefly discussed.

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DO - 10.1021/ic0354062

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AN - SCOPUS:1842536855

SN - 0020-1669

VL - 43

SP - 2355

EP - 2367

JO - Inorganic Chemistry

JF - Inorganic Chemistry

IS - 7

ER -

Mononuclear and Dinuclear Complexes of Dibenzoeilatin: Synthesis, Structure, and Electrochemical and Photophysical Properties

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