G‐Quadruplex Supramolecular Assemblies in Photochemical Upconversion

Mutsamwira, Saymore; Ainscough, Eric W.; Partridge, Ashton; Derrick, Peter J.; Filichev, Vyacheslav V.

doi:10.1002/chem.201601353

Cited by 16 publications

(13 citation statements)

References 45 publications

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“…Balzani, Ceroni et al.’s alternative mechanistic proposal included an additional step involving triplet–triplet annihilation of pyrene generating pyrene in its singlet‐excited state. Their proposal is based on earlier publications reporting the Ru(bpy) 3 2+ sensitized triplet–triplet annihilation of a pyrene derivative (in supramolecular assemblies), and applications of triplet–triplet annihilated excited singlet species, generated under laser irradiation, for photoredox applications . We would like to emphasize that the same papers (see Refs.…”

Section: Figurementioning

confidence: 92%

Reply to “Photoredox Catalysis: The Need to Elucidate the Photochemical Mechanism”

2017

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Spektroskopische Messungen und abgeschätzte thermodynamische Werte sind wichtige Hilfsmittel für mechanistische Untersuchungen von Photokatalysen. Messwerte, die nur unter idealisierten Bedingungen ermittelt werden und die Komplexität präparativer organischer Reaktionsgemische ausblenden, sind allerdings wenig geeignet, um mechanistische Hypothesen zu beweisen oder Syntheseausbeuten und ‐selektivitäten zu verbessern.

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Section: Figurementioning

confidence: 92%

Reply to “Photoredox Catalysis: The Need to Elucidate the Photochemical Mechanism”

2017

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“…Due to the remarkable ability of TINA-insertions to stabilize NA complexes through intercalation, various TINA-modified oligonucleotides have been further studied as dsDNA targeting fluorescence probes [ 216 , 219 , 220 ], ssDNA targeting fluorescent probes with increased sensitivity and specificity [ 221 ], improved primers for PCR assays [ 222 ], G-quadruplex-forming oligonucleotides [ 223 , 224 , 225 , 226 , 227 , 228 ], i-motif-forming oligonucleotides [ 229 ], aptamers with improved activity [ 230 ], probes for DNA duplex invasion [ 231 ], and antisense oligonucleotides for splice modulation by induced exon-skipping in vitro [ 232 ]. Interestingly, modification of a template oligonucleotide by 5′-terminal o TINA was shown to reduce or even inhibit of a non-templated nucleotide addition activity of DNA polymerases [ 233 ].…”

Section: Agents For Targeting Of Dsdnasmentioning

confidence: 99%

Recent Advances in Nucleic Acid Targeting Probes and Supramolecular Constructs Based on Pyrene-Modified Oligonucleotides

et al. 2017

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In this review, we summarize the recent advances in the use of pyrene-modified oligonucleotides as a platform for functional nucleic acid-based constructs. Pyrene is of special interest for the development of nucleic acid-based tools due to its unique fluorescent properties (sensitivity of fluorescence to the microenvironment, ability to form excimers and exciplexes, long fluorescence lifetime, high quantum yield), ability to intercalate into the nucleic acid duplex, to act as a π-π-stacking (including anchoring) moiety, and others. These properties of pyrene have been used to construct novel sensitive fluorescent probes for the sequence-specific detection of nucleic acids and the discrimination of single nucleotide polymorphisms (SNPs), aptamer-based biosensors, agents for binding of double-stranded DNAs, and building blocks for supramolecular complexes. Special attention is paid to the influence of the design of pyrene-modified oligonucleotides on their properties, i.e., the structure-function relationships. The perspectives for the applications of pyrene-modified oligonucleotides in biomolecular studies, diagnostics, and nanotechnology are discussed.

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“…[8,9] Recently,a ne xample of this upconversion mechanism has been reported with [Ru(bpy) 3 ] 2+ and ap yrene derivative. [10] Also in the case of pristine pyrene,w eh ave observed that selective excitation of [Ru(bpy) 3 ] 2+ at 532 nm in the presence of 0.01m pyrene in DMSO causes population of Py(S 1 ), as evidenced by the appearance of delayed fluorescence of pyrene,occurring on the mstime scale (see Figure S2 in the Supporting Information).…”

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confidence: 98%

Photoredox Catalysis: The Need to Elucidate the Photochemical Mechanism

et al. 2017

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electron transfer ·photocatalysis ·pyrenes ·triplettriplet annihilation ·tris(bipyridine)ruthenium (II) During the last decade photocatalysis in organic synthesis has become ab looming field of research. [1][2][3] In most cases, photocatalytic reactions involve electron transfer processes that yield highly reducing or oxidizing intermediates.In search of highly reducing species generated upon visible light excitation, arecent Communication published in this journal [4] reports the use of av isible-light absorbing photocatalyst, namely [Ru(bpy) 3 ] 2+ ,toproduce radical anions of UV-absorbing polycyclic aromatic hydrocarbons,s uch as pyrene,w hich in turn were able to drive the reductive activation of chemical bonds for carbon-carbon and carbonheteroatom bond formation.Thep roposed photochemical mechanism mimics that of the natural photosynthesis:l ight absorption, followed by energy transfer and electron transfer steps,asdescribed by the following scheme (the relevant electronic excited states participating in the reactions are shown in parentheses).½RuðbpyÞ 3 2þ ðS 1 Þ!½ RuðbpyÞ 3 2þ ðT 1 Þ ð2Þ ½RuðbpyÞ 3 2þ ðT 1 ÞþPy !½ RuðbpyÞ 3 2þ þ PyðT 1 Þ ð3ÞUpon light excitation of [Ru(bpy) 3 ] 2+ ,t he lowest triplet excited state of the Ru II complex (T 1 ), which is populated quantitatively by the S 1 !T 1 intersystem crossing (processes 1a nd 2), sensitizes the population of the triplet state of pyrene,P y(T 1 )( by triplet-triplet energy transfer, process 3). Py(T 1 )i ss ubsequently reduced by N,N-diisopropylethylamine (DIPEA, reaction 4), resulting in formation of astrongly reducing pyrene radical anion (Py À ), which is able to drive the reduction of organic substrates.H owever,n o experimental evidence supporting the formation of the radical anion of pyrene was reported.We would like to note that, based on the thermodynamic data, the pyrene radical anion is highly unlikely to form as proposed in the scheme (Figure 1, black lines). To af irst approximation, that is,n eglecting the electrostatic work term, [5] the free energy change of the photoinduced outersphere electron transfer reaction can be obtained [6] from the redox potentials of the ground state couples and the oneelectron potential corresponding to the zero-zero excitation energy,according to the values reported and discussed in the original paper: [4] E[Py(T 1 )/Py À ] = E[Py/Py À ] + E 00 [Py/Py(T 1 )] = À2.1 + 2.0 = À0.1 V E[DIPEA + /DIPEA] =+0.9 Vvs. SCE [7] In the case of reaction (4):Therefore,r eaction (4) is highly endoergonic and its occurrence ( Figure 1) is extremely unlikely.Indeed, even the electron transfer quenching of [Ru(bpy) 3 ] 2+ (T 1 )b yDIPEA, which is much less endoergonic (ca. 0.2 eV), was reported to be extremely slow. [4] Apossible alternative,thermodynamically allowed mechanism (Figure 1), underpinning formation of the pyrene radical anion and subsequent reduction of organic substrates, could involve energy transfer from the photoexcited Ru II complex to pyrene [reaction (3)],f ollowed by triplet-triplet annihilation of two ...

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G‐Quadruplex Supramolecular Assemblies in Photochemical Upconversion

Cited by 16 publications

References 45 publications

Reply to “Photoredox Catalysis: The Need to Elucidate the Photochemical Mechanism”

Reply to “Photoredox Catalysis: The Need to Elucidate the Photochemical Mechanism”

Recent Advances in Nucleic Acid Targeting Probes and Supramolecular Constructs Based on Pyrene-Modified Oligonucleotides

Photoredox Catalysis: The Need to Elucidate the Photochemical Mechanism

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