Synthesis and Characterization of a Novel Linear Trinuclear Ruthenium(II) Complex:  Variation of Photosensitization Ability with Chain Length in a Homologous Series

Vaduvescu, Simona; Potvin, Pierre

doi:10.1021/ic025511w

Cited by 10 publications

(3 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The ligand 1,4-bis-(2,2′:6′2′′-terpyridine-4′-yl)-benzene and Fe−MEPE (see Scheme a) were synthesized as described elsewhere. − Terephthaldialdehyde, acetylpyridine, ammonia solution (25%), and ethanol were purchased from Sigma-Aldrich and used without further purification. Throughout this work, Fe−MEPE was used in the form of the acetate salt.…”

Section: Methodsmentioning

confidence: 99%

Carboxylic Acid-Doped SBA-15 Silica as a Host for Metallo-supramolecular Coordination Polymers

et al. 2008

View full text Add to dashboard Cite

The adsorption of a metallo-supramolecular coordination polymer (Fe-MEPE) in the cylindrical pores of SBA-15 silica with pure and carboxylic acid (CA) carrying pore walls has been studied. Fe-MEPE is an intrinsically stiff polycation formed by complexation of Fe(II)-acetate with an uncharged ditopic bis-terpyridine ligand. The adsorption affinity and kinetics of the Fe-MEPE chains is strongly enhanced when the pore walls are doped with CA, and when the pH of the aqueous medium or temperature is increased. The initial fast uptake is connected with a decrease of pH of the aqueous solution, indicating an ion-exchange mechanism. It is followed by a slower (presumably diffusion-controlled) further uptake. The maximum adsorbed amount of Fe-MEPE in the CA-doped material corresponds to a monolayer of Fe-MEPE chains disposed side-by-side along the pore walls. The stoichiometry of Fe-MEPE in the pores (determined by XPS) was found to be independent of the loading and similar to that of the starting material. The mean chain length of Fe-MEPE before and after embedding in the CA-doped matrix was studied by solid-state 15N NMR using partially 15N-labeled Fe-MEPE. It is shown that the average chain length of Fe-MEPE is reduced when the complex is incorporated in the pores.

show abstract

Section: Methodsmentioning

confidence: 99%

Carboxylic Acid-Doped SBA-15 Silica as a Host for Metallo-supramolecular Coordination Polymers

et al. 2008

View full text Add to dashboard Cite

show abstract

“…With respect to the latter, we have recently developed an expedient method for the comparative assessment of sensitization ability, one that avoids the laborious determination of a sensitizer's fundamental photophysical properties. We have since applied this method to the assessment of a few new candidates in comparisons with well-known materials under identical conditions. − With respect to the problem of design, we have endeavored to address two of the basic issues plaguing Ru II -based sensitizers, namely unfavorable electrostatics and photoproduct separation.…”

Section: Introductionmentioning

confidence: 99%

Electrostatic Bubbles and Supramolecular Assistance of Photosensitization by Carboxylated Ru(II) Complexes

2003

Self Cite

View full text Add to dashboard Cite

The paper examines the supramolecular effects at play during photosensitization by carboxylated Ru(II) sensitizers, both by experiment and by modeling. Experimentally, twelve Ru(II) complexes of pyrazolylpyridine and polypyridine ligands, including two benchmark complexes and two new species, were assessed as photosensitizers by measurement of the kinetics of methyl viologen cation radical (MV(*)(+)) generation through an oxidative, photoinduced electron transfer (PET) to methyl viologen (MV(2+)) under continuous irradiation in the presence of a sacrificial reductant. All complexes, luminescent or not, produced measurable amounts of MV(*)(+) in CH(3)CN. The assessment protocol was found to be useful with sensitizers of widely varying excited-state lifetimes (tau) as well as being easier and faster than conventional approaches. The seven sensitizers bearing peripheral COOH groups were found to be significantly more active than their non-carboxylated analogues, which is consistent with ionization of the COOH groups and electrostatic promotion of PET. Only the luminescent complexes were active in aqueous solvents, where tau appears to be the dominant effector. The benefits are exemplified by the singly carboxylated [Ru(H1)(bpy)(2)](2+) (H1 is 1-(4-carboxyphenyl)-3-(2-pyridyl)-4,5,6,7-tetrahydroindazole), a weakly luminescent sensitizer that was less active in aqueous solvents than [Ru(bpy)(3)](2+) (bpy is 2,2'-bipyridine), but which became the better sensitizer in CH(3)CN. Computationally, electrostatic field and dissociation energy calculations demonstrated that even a single peripheral COO(-) substituent suffices to provide supramolecular assistance: it defines a spheric "bubble" of electrostatically attractive space that is sufficiently large to allow the supramolecular preassociation of MV(2+), which provides an entropic advantage to PET that reduces the importance of tau in organic solvent. Calculations also show that the PET is electrostatically favored over its reverse (BET) even with cationic sensitizers because the "bubble" contracts after PET while the bulk medium becomes more repulsive, and favorable cation exchanges can occur to effect post-PET dissociation. Two peripheral COO(-) groups can define a two-point binding site for MV(2+) in an attractive sector of space that contracts to a kidney-shaped "bubble" after PET. This enables unimolecular PET while the reverse reaction remains bimolecular. The resultant benefits are illustrated with [Ru(Na1)(2)(bpy)](2+), a very weakly luminescent sensitizer that was totally inactive in H(2)O but appreciably active in CH(3)CN, despite the need to displace Na(+) in order to derive any electrostatic benefit. The Marcus free energies of activation for PET and BET corroborate the benefits of carboxylation, solvent, and other factors and correlated with the experimental rate constants.

show abstract

“…Comment 1,4-Bis(2,2 H :6 H ,2 HH -terpyridin-4 H -yl)benzene, the so-called`backto-back' bis(terpyridine), is known (Kro È hnke, 1976;Constable & Cargill-Thompson, 1992;Vaduvescu & Potvin, 2002) and has been used as a bridging ligand in polynuclear complexes of Ru and other metals (Collin et al, 1993;Barigelletti et al, 1994;Janini et al, 1999;Vaduvescu & Potvin, 2002), but has apparently not appeared in any crystal structure. The title compound, (I), is the meta-linked isomer, which has been prepared to study the electrochemical and spectroscopic properties of the analogous di-and trinuclear Ru complexes lacking a resonance route of communication between metal centres.…”

mentioning

confidence: 99%

1,3-Bis(2,2′:6′,2′′-terpyridin-4′-yl)benzene, a new dinucleating bis(tridentate) ligand, as its dichloromethane solvate

Vaduvescu

Potvin

2003

Acta Cryst E

Self Cite

View full text Add to dashboard Cite

Key indicatorsSingle-crystal X-ray study T = 150 K Mean '(C±C) = 0.004 A Ê Disorder in solvent or counterion R factor = 0.063 wR factor = 0.175 Data-to-parameter ratio = 12.3For details of how these key indicators were automatically derived from the article, seeThe title compound, 1,3-bis(2,2 H :6 H ,2 HH -terpyridin-4 H -yl)benzene dichloromethane solvate, C 36 H 24 N 6 ÁCH 2 Cl 2 , is a new ligand suitable for bridging two metal centres. Though not in binding conformations, its two terpyridine units are linked in a unique arrangement, through a meta-phenylene core, which disallows resonance communication between binding sites, as re¯ected by the crystal structure of its 1:1 CH 2 Cl 2 solvate. The two terpyridine units are related by crystallographically imposed twofold symmetry, forming a 30.02 (8) dihedral angle with the phenylene core, but with fairly coplanar pyridine rings within. The solvent molecule is disordered over the twofold axis.

show abstract

Synthesis and Characterization of a Novel Linear Trinuclear Ruthenium(II) Complex: Variation of Photosensitization Ability with Chain Length in a Homologous Series

Cited by 10 publications

References 16 publications

Carboxylic Acid-Doped SBA-15 Silica as a Host for Metallo-supramolecular Coordination Polymers

Carboxylic Acid-Doped SBA-15 Silica as a Host for Metallo-supramolecular Coordination Polymers

Electrostatic Bubbles and Supramolecular Assistance of Photosensitization by Carboxylated Ru(II) Complexes

1,3-Bis(2,2′:6′,2′′-terpyridin-4′-yl)benzene, a new dinucleating bis(tridentate) ligand, as its dichloromethane solvate

Contact Info

Product

Resources

About