Energy level tailoring in ruthenium(II) polyazine complexes based on calculated and experimental ligand properties

Ernst, Sylvia; Kaim, Wolfgang

doi:10.1021/ic00307a020

Cited by 173 publications

(113 citation statements)

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“…A broad, asymmetric absorption band extending from 390 to 550 nm is accounted for by the superposition of low-energy π-π* intra-DppztBuSalH 2 -ligand transitions and an admixture of dπ(Ru)-π*(bpy) together with dπ(Ru)-π* (bpyЈ) (where bpyЈ denotes the bipyridine moiety of the ligand 7) MLCT transitions. This agrees with previous findings for (polypyridine)ruthenium() complexes containing extended delocalised π-systems, where it has been shown that the low-lying orbitals confined on the central part of the rigid aromatic ligand are decou- pled from the metal t 2g -type orbitals [26] due to the nearly non-existent orbital contribution from the nitrogen atoms of the coordinating imino groups. Hence, the optical properties of 11 suggest a bichromophoric character for the complex.…”

Section: Uv/vis Spectroscopysupporting

confidence: 92%

“…[26,27] This implies that the coordination of ligand 7 to the Ru II ion has little influence on the uptake of the first electron. Another way to describe this result is to consider that the singly occupied molecular orbital (SOMO) is developed mainly on the phenazine together with the bis(salicylidene)diimine framework.…”

Section: Singly Reduced Forms Of [Ru(bpy) 2 Dppztbusalh 2 ] 2؉ (11) Amentioning

confidence: 99%

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A Rigid Molecular Scaffold Affixing a (Polypyridine)ruthenium(II)‐ and a Nickel(II)‐Containing Complex: Spectroscopic Evidence for a Weakly Coupled Bichromophoric System

et al. 2003

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The synthesis of DppztBuSalH2 (7), a rigid conjugated ditopic ligand containing a Dppz (dipyrido[3,2‐a:2′,3′‐c]phenazine) skeleton and a salophen‐type chelate, is reported. The complexes DppztBuSalNi (10), [Ru(bpy)2(DppztBuSalH2)]2+ (11), and [Ru(bpy)2(DppztBuSalNi)]2+ (12) have been prepared and characterised using common spectroscopic methods. Electrochemical, UV/Vis spectroelectrochemical and EPR studies were conducted on compounds 7, 10, 11, and 12. The singly reduced radical forms of 7 and 10 can be generated electrochemically, with the lone electron located on the low‐lying phenazine π*‐molecular orbital. Complexes 11 and 12 show several reduction waves and electronic and EPR data obtained for the electrogenerated singly reduced species show them to be closely related to the radical species 7·− and 10·−, respectively. The presence of nickel(II) in compound 12 renders the addition of the second electron on the phenazine group reversible. Both 11 and 12 show common features on the cathodic side of their cyclic voltammograms, with reversible one‐electron ruthenium‐centred oxidation. An additional low‐potential reversible‐oxidation wave is observed for 12, and this is ascribed to oxidation of the nickel(II) ion. The combined spectroscopic data best describe the ruthenium‐containing complexes as weakly coupled bichromophoric systems. Photophysical studies attest to the formation of a charge‐separated state for 11, whereas a strong quenching is detected for 12. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

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Section: Uv/vis Spectroscopysupporting

confidence: 92%

Section: Singly Reduced Forms Of [Ru(bpy) 2 Dppztbusalh 2 ] 2؉ (11) Amentioning

confidence: 99%

A Rigid Molecular Scaffold Affixing a (Polypyridine)ruthenium(II)‐ and a Nickel(II)‐Containing Complex: Spectroscopic Evidence for a Weakly Coupled Bichromophoric System

et al. 2003

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“…Three reversible reduction processes attributable to the ligand (9) are also present, at El/2 = -0.55, -1.09 and -1.30 V. Similar behaviour is observed for Cr, Mo and W carbonyl complexes (6, v). In our case, oxidation processes occur only for the cobalt(II) ion at 0.7 V in an irreversible manner.…”

Section: Electrochemistrysupporting

confidence: 68%

Complexes with diimine ligands. Syntheses and magnetic behaviour of dinuclear complexes of copper(II), nickel(II) and cobalt(II) with 2,5-bis(2-pyridyl)pyrazine

Escuer

Comas

Vicente

et al. 1993

Transition Met Chem

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The synthesis, characterization and voltammetric and magnetic behaviour of a series of dinuclear complexes #-(2,5-DPP)[-M(hfacac)2]2, in which hfacac is hexafluoroacetylacetonate, 2,5-DPP is 2,5-bis(2-pyridyl)pyrazine and M = copper(II), nickel(II) and cobalt(II), are described. As with the dinuclear complexes derived from 2,3-bis(2-pyridyl)-pyrazine (2,3-DPP) and analogous ligands, magnetic measurements show that these systems are not coupled. On the basis of magnetic data, we propose that, in contrast to related ligands such as 2,2'-bipyridyl, the coordinated 2,5-DPP cannot be planar.

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“…The data are summarized in Table 7. In particular, for [Ru(bpy)2(bpz)] 2+ and [Ru-(bpy)2(bpdz)] ~+, the lowest excited states are -in general agreement [85,196,198,210,[248][249][250][251][252][253] -localized on the (Ru-bpz) and the (Ru-bpdz) subunit, respectively. Interestingly, in these situations the values of zfs zlE~_i1 and AEI_ m are ~100% and ~70% larger, respectively, than those for the related tris compounds [Ru(bpz)3] 2+ and [Ru(bpdz)3]2+.…”

Section: Localized Situation In [Ru(i-biq)2(bpy)2] 2 §mentioning

confidence: 94%

Characterization of excited electronic and vibronic states of platinum metal compounds with chelate ligands by highly frequency-resolved and time-resolved spectra

Yersin

Humbs

Strasser

1997

Topics in Current Chemistry

133

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The lowest excited electronic states of triplet character and related vibronic properties are discussed in detail on the basis of highly frequency-resolved and time-resolved emission and excitation spectra of per-protonated, per-deuterated, and partially deuterated [Pt(bpy)2] 2+, [Rh(bpy)3] 3+, [Ru(bpy)3] 2+, and [Os(bpy)3] ~+. Emphasis is placed on the use of the enormous amount of information displayed in well-resolved vibrational satellite structures. For comparison, IR data and Raman spectra are also used. In addition, data are given for [Ru(bpz)Pt(3-thpy) 2, Pt(2-thpy)(CO)(Cl), Pt(2-thpy) 2, Pt(qol)2, Pt(qtl)2. Trends and effects are also addressed, which are related to the amount of metal d-orbital mixing. In particular, we discuss the role of traps and sites in the context of high-resolution, site-selective, and line-narrowed spectra of chromophores doped into matrices; the interplay between states of ligand-centered 3rtrr* and ~MLCT character; localization versus delocalization behavior; radiative decay properties; zero-field splittings; spin-lattice relaxations via direct and Orbach mechanisms; Arrhenius behavior after time delay; Franck-Condon activities and Huang-Rhys factors; Franck-Condon versus Herzberg Teller activities and tunability of these activities under high magnetic fields; isotope marking and deuteration effects; aggregate formation of [Ru(bpy)3]2+; and radiationless energy transfer in neat [Ru(bpy)3](PF6) 2. These effects are in part treated in detail, but the aim is to use easy-to-follow descriptions. In particular, it is emphasized throughout this review that chemical tunability opens fascinating possibilities for controlled variation of physical properties.

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Energy level tailoring in ruthenium(II) polyazine complexes based on calculated and experimental ligand properties

Cited by 173 publications

References 0 publications

A Rigid Molecular Scaffold Affixing a (Polypyridine)ruthenium(II)‐ and a Nickel(II)‐Containing Complex: Spectroscopic Evidence for a Weakly Coupled Bichromophoric System

A Rigid Molecular Scaffold Affixing a (Polypyridine)ruthenium(II)‐ and a Nickel(II)‐Containing Complex: Spectroscopic Evidence for a Weakly Coupled Bichromophoric System

Complexes with diimine ligands. Syntheses and magnetic behaviour of dinuclear complexes of copper(II), nickel(II) and cobalt(II) with 2,5-bis(2-pyridyl)pyrazine

Characterization of excited electronic and vibronic states of platinum metal compounds with chelate ligands by highly frequency-resolved and time-resolved spectra

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