Photoinduced Formation and Characterization of Electron–Hole Pairs in Azaxanthylium‐Derivatized Short Single‐Walled Carbon Nanotubes

Martín, Roberto; Jiménez, Liliana; Álvaro, Mercedes; Scaiano, Juan C.; Garcı́a, Hermenegildo

doi:10.1002/chem.200900372

Cited by 12 publications

(12 citation statements)

References 63 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The transient spectra recorded at several time delays after the 490 nm laser pulse is characterized by a continuous absorption spanning the complete wavelength range, very similar to those previously observed in the laser flash photolysis of other chromophore‐SWCNTs such as azaxanthone covalently attached to a SWCNT 43. In addition to this continuous absorption, some weaker features in the regions λ =350–390 and 500–600 nm compatible with the absorption spectrum of [Ru(bpy) 3 ] + were also observed.…”

Section: Resultssupporting

confidence: 72%

“…49, 50 On the other hand, it is also known that SWCNTs can behave as semiconductors, accepting or donating electrons 51. 52 The mobility of electron and holes in SWCNTs is also very large 43. Based on this previous knowledge, we propose a plausible mechanism to rationalize the time‐resolved spectroscopic study of Ru‐SWCNT and particularly for how a two‐photon process generates the delayed formation of [Ru(bpy) 3 ] + .…”

Section: Resultsmentioning

confidence: 74%

See 1 more Smart Citation

Rationalization and In Vitro Modeling of the Chemical Mechanisms of the Enzymatic Oxidation of Phenolic Compounds in Planta: From Flavonols and Stilbenoids to Lignins

Cottyn

Kollmann

Waffo-Téguo

et al. 2011

Chemistry A European J

View full text Add to dashboard Cite

Enzymatic oxidation of phenolic compounds is a widespread phenomenon in plants. It is responsible for the formation of many oligomers and polymers, which are generally described as the result of a combinatorial coupling of the different radicals formed through oxidation of the phenol group and delocalization of the radical. We focused our interest on several phenolic compounds that are present in plants and known to form, under enzymatic oxidation, oligomers with different type of linkages between monomers. To explain this diversity of inter-monomer linkages and their variation according to the experimental procedure used for the enzymatic oxidation, we report an alternative mechanistic pathway involving dismutation of the radicals, leading to the formation of carbocations which, thereafter, react with nucleophilic species present in the medium. This alternative pathway allows the understanding of peculiar linkages between monomeric units in the oligomer and offers new insights for understanding the formation of phenolic biopolymers in plants.

show abstract

Section: Resultssupporting

confidence: 72%

Section: Resultsmentioning

confidence: 74%

Rationalization and In Vitro Modeling of the Chemical Mechanisms of the Enzymatic Oxidation of Phenolic Compounds in Planta: From Flavonols and Stilbenoids to Lignins

Cottyn

Kollmann

Waffo-Téguo

et al. 2011

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…[51,52] The mobility of electron and holes in SWCNTs is also very large. [43] Based on this previous knowledge, we propose a plausible mechanism to rationalize the time-resolved spectroscopic study of Ru-SWCNT and particularly for how a two-photon process generates the delayed formation of [Ru-…”

Section: Mechanistic Proposal For the Delayed [Rua C H T U N G T R E mentioning

confidence: 99%

Two‐Photon Chemistry in Ruthenium 2,2′‐Bipyridyl‐Functionalized Single‐Wall Carbon Nanotubes

Martín¹,

Jiménez²,

Álvaro³

et al. 2010

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

Ruthenium polypyridyl complexes are widely used as light harvesters in dye-sensitized solar cells. Since one of the potential applications of single-wall carbon nanotubes (SWCNTs) and their derived materials is their use as active components in organic and hybrid solar cells, the study of the photochemistry of SWCNTs with tethered ruthenium polypyridyl complexes is important. A water-soluble ruthenium tris(bipyridyl) complex linked through peptidic bonds to SWCNTs (Ru-SWCNTs) was prepared by radical addition of thiol-terminated SWCNT to a terminal C=C double bond of a bipyridyl ligand of the ruthenium tris(bipyridyl) complex. The resulting macromolecular Ru-SWCNT (approximately 500 nm, 15.6% ruthenium complex content) was water-soluble and was characterized by using TEM, thermogravimetric analysis, chemical analysis, and optical spectroscopy. The emission of Ru-SWCNT is 1.6 times weaker than that of a mixture of [Ru(bpy)(3)](2+) and SWCNT of similar concentration. Time-resolved absorption optical spectroscopy allows the detection of the [Ru(bpy)(3)](2+)-excited triplet and [Ru(bpy)(3)](+). The laser flash studies reveal that Ru-SWCNT exhibits an unprecedented two-photon process that is enabled by the semiconducting properties of the SWCNT. Thus, the effect of the excitation wavelength and laser power on the transient spectra indicate that upon excitation of two [Ru(bpy)(3)](2+) complexes of Ru-SWCNT, a disproportionation process occurs leading to delayed formation of [Ru(bpy)(3)](+) and the performance of the SWCNT as a semiconductor. This two-photon delayed [Ru(bpy)(3)](+) generation is not observed in the photolysis of [Ru(bpy)(3)](3+); SWCNT acts as an electron wire or electron relay in the disproportionation of two [Ru(bpy)(3)](2+) triplets in a process that illustrates that the SWCNT plays a key role in the process. We propose a mechanism for this two-photon disproportionation compatible with i) the need for high laser flux, ii) the long lifetime of the [Ru(bpy)(3)](2+) triplets, iii) the semiconducting properties of the SWNT, and iv) the energy of the HOMO/LUMO levels involved.

show abstract

“…200 Another method towards obtaining five membered ring azaxanthones was proposed by Singh et al 201 Starting from a nitrone 210, 2-anilino-6-chloro-3-formylchromone (211) was formed in dry benzene, with a few drops of acetic acid (Scheme 25D). A reaction with methyl-iodide in the presence of potassium carbonate in acetone yielded 6-chloro-2-(Nmethylanilino)-3-formylchromone (212), which upon reaction with hydrazine hydrate in aqueous acetonitrile overnight afforded the azaxanthone 213 (Scheme 25D) in 43% overall yield.…”

Section: Synthesis Of Azaxanthone-derivatives: the Case Of Fivemembermentioning

confidence: 99%

Recent advances in the synthesis of xanthones and azaxanthones

et al. 2020

View full text Add to dashboard Cite

show abstract

Photoinduced Formation and Characterization of Electron–Hole Pairs in Azaxanthylium‐Derivatized Short Single‐Walled Carbon Nanotubes

Cited by 12 publications

References 63 publications

Rationalization and In Vitro Modeling of the Chemical Mechanisms of the Enzymatic Oxidation of Phenolic Compounds in Planta: From Flavonols and Stilbenoids to Lignins

Rationalization and In Vitro Modeling of the Chemical Mechanisms of the Enzymatic Oxidation of Phenolic Compounds in Planta: From Flavonols and Stilbenoids to Lignins

Two‐Photon Chemistry in Ruthenium 2,2′‐Bipyridyl‐Functionalized Single‐Wall Carbon Nanotubes

Recent advances in the synthesis of xanthones and azaxanthones

Contact Info

Product

Resources

About