N-alkoxyheterocycles as irreversible photooxidants

Zofia M. Wosinska, Faye L. Stump, Rajeev Ranjan, Edward D. Lorance, Genita N. Finley, Priya P. Patel, Muzamil A. Khawaja, Katie L. Odom, Wolfgang H. Kramer, Ian Gould

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Irreversible photooxidation based on N-O bond fragmentation is demonstrated for N-methoxyheterocycles in both the singlet and triplet excited state manifolds. The energetic requirements for bond fragmentation are studied in detail. Bond fragmentation in the excited singlet manifold is possible for ππ* singlet states with energies significantly larger than the N-O bond dissociation energy of ca 55 kcal mol-1. For the nπ* triplet states, N-O bond fragmentation does not occur in the excited state for orbital overlap and energetic reasons. Irreversible photooxidation occurs in the singlet states by bond fragmentation followed by electron transfer. Irreversible photooxidation occurs in the triplet states via bimolecular electron transfer to the donor followed by bond fragmentation. Using these two sensitization schemes, donors can be irreversibly oxidized with oxidation potentials ranging from ca 1.6-2.2 V vs SCE. The corresponding N-ethylheterocycles are characterized as conventional reversible photooxidants in their triplet states. The utility of these sensitizers is demonstrated by irreversibly generating the guanosine radical cation in buffered aqueous solution. The return or reverse electron transfer that occurs in the primary charge-separated pair that is a feature of all photoinduced electron transfer reactions wastes energy and competes with useful chemistry in the charge-separated species. Here, we describe photoinduced electron transfer schemes that made irreversible by using fragmentable sensitizers. The fragmentable sensitizers are N-methoxyheterocycles that cleave a relatively weak N-O bond in either their reduced or excited forms. Sensitization mechanisms in both the singlet and the triplet manifolds are described. Irreversible oxidation of guanosine is demonstrated as an illustrative example.

Original languageEnglish (US)
Pages (from-to)313-328
Number of pages16
JournalPhotochemistry and Photobiology
Volume90
Issue number2
DOIs
StatePublished - 2014

Fingerprint

fragmentation
Photooxidation
Electrons
electron transfer
photooxidation
Guanosine
atomic energy levels
guanosines
Excited states
Oxidation
oxidation
Cations
excitation
energy
dissociation
chemistry
aqueous solutions
cations
orbitals
requirements

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Biochemistry
  • Medicine(all)

Cite this

Wosinska, Z. M., Stump, F. L., Ranjan, R., Lorance, E. D., Finley, G. N., Patel, P. P., ... Gould, I. (2014). N-alkoxyheterocycles as irreversible photooxidants. Photochemistry and Photobiology, 90(2), 313-328. https://doi.org/10.1111/php.12227

N-alkoxyheterocycles as irreversible photooxidants. / Wosinska, Zofia M.; Stump, Faye L.; Ranjan, Rajeev; Lorance, Edward D.; Finley, Genita N.; Patel, Priya P.; Khawaja, Muzamil A.; Odom, Katie L.; Kramer, Wolfgang H.; Gould, Ian.

In: Photochemistry and Photobiology, Vol. 90, No. 2, 2014, p. 313-328.

Research output: Contribution to journalArticle

Wosinska, ZM, Stump, FL, Ranjan, R, Lorance, ED, Finley, GN, Patel, PP, Khawaja, MA, Odom, KL, Kramer, WH & Gould, I 2014, 'N-alkoxyheterocycles as irreversible photooxidants', Photochemistry and Photobiology, vol. 90, no. 2, pp. 313-328. https://doi.org/10.1111/php.12227
Wosinska ZM, Stump FL, Ranjan R, Lorance ED, Finley GN, Patel PP et al. N-alkoxyheterocycles as irreversible photooxidants. Photochemistry and Photobiology. 2014;90(2):313-328. https://doi.org/10.1111/php.12227
Wosinska, Zofia M. ; Stump, Faye L. ; Ranjan, Rajeev ; Lorance, Edward D. ; Finley, Genita N. ; Patel, Priya P. ; Khawaja, Muzamil A. ; Odom, Katie L. ; Kramer, Wolfgang H. ; Gould, Ian. / N-alkoxyheterocycles as irreversible photooxidants. In: Photochemistry and Photobiology. 2014 ; Vol. 90, No. 2. pp. 313-328.
@article{9bdbd49c0dae469d8ff09d4e1482c25c,
title = "N-alkoxyheterocycles as irreversible photooxidants",
abstract = "Irreversible photooxidation based on N-O bond fragmentation is demonstrated for N-methoxyheterocycles in both the singlet and triplet excited state manifolds. The energetic requirements for bond fragmentation are studied in detail. Bond fragmentation in the excited singlet manifold is possible for ππ* singlet states with energies significantly larger than the N-O bond dissociation energy of ca 55 kcal mol-1. For the nπ* triplet states, N-O bond fragmentation does not occur in the excited state for orbital overlap and energetic reasons. Irreversible photooxidation occurs in the singlet states by bond fragmentation followed by electron transfer. Irreversible photooxidation occurs in the triplet states via bimolecular electron transfer to the donor followed by bond fragmentation. Using these two sensitization schemes, donors can be irreversibly oxidized with oxidation potentials ranging from ca 1.6-2.2 V vs SCE. The corresponding N-ethylheterocycles are characterized as conventional reversible photooxidants in their triplet states. The utility of these sensitizers is demonstrated by irreversibly generating the guanosine radical cation in buffered aqueous solution. The return or reverse electron transfer that occurs in the primary charge-separated pair that is a feature of all photoinduced electron transfer reactions wastes energy and competes with useful chemistry in the charge-separated species. Here, we describe photoinduced electron transfer schemes that made irreversible by using fragmentable sensitizers. The fragmentable sensitizers are N-methoxyheterocycles that cleave a relatively weak N-O bond in either their reduced or excited forms. Sensitization mechanisms in both the singlet and the triplet manifolds are described. Irreversible oxidation of guanosine is demonstrated as an illustrative example.",
author = "Wosinska, {Zofia M.} and Stump, {Faye L.} and Rajeev Ranjan and Lorance, {Edward D.} and Finley, {Genita N.} and Patel, {Priya P.} and Khawaja, {Muzamil A.} and Odom, {Katie L.} and Kramer, {Wolfgang H.} and Ian Gould",
year = "2014",
doi = "10.1111/php.12227",
language = "English (US)",
volume = "90",
pages = "313--328",
journal = "Photochemistry and Photobiology",
issn = "0031-8655",
publisher = "Wiley-Blackwell",
number = "2",

}

TY - JOUR

T1 - N-alkoxyheterocycles as irreversible photooxidants

AU - Wosinska, Zofia M.

AU - Stump, Faye L.

AU - Ranjan, Rajeev

AU - Lorance, Edward D.

AU - Finley, Genita N.

AU - Patel, Priya P.

AU - Khawaja, Muzamil A.

AU - Odom, Katie L.

AU - Kramer, Wolfgang H.

AU - Gould, Ian

PY - 2014

Y1 - 2014

N2 - Irreversible photooxidation based on N-O bond fragmentation is demonstrated for N-methoxyheterocycles in both the singlet and triplet excited state manifolds. The energetic requirements for bond fragmentation are studied in detail. Bond fragmentation in the excited singlet manifold is possible for ππ* singlet states with energies significantly larger than the N-O bond dissociation energy of ca 55 kcal mol-1. For the nπ* triplet states, N-O bond fragmentation does not occur in the excited state for orbital overlap and energetic reasons. Irreversible photooxidation occurs in the singlet states by bond fragmentation followed by electron transfer. Irreversible photooxidation occurs in the triplet states via bimolecular electron transfer to the donor followed by bond fragmentation. Using these two sensitization schemes, donors can be irreversibly oxidized with oxidation potentials ranging from ca 1.6-2.2 V vs SCE. The corresponding N-ethylheterocycles are characterized as conventional reversible photooxidants in their triplet states. The utility of these sensitizers is demonstrated by irreversibly generating the guanosine radical cation in buffered aqueous solution. The return or reverse electron transfer that occurs in the primary charge-separated pair that is a feature of all photoinduced electron transfer reactions wastes energy and competes with useful chemistry in the charge-separated species. Here, we describe photoinduced electron transfer schemes that made irreversible by using fragmentable sensitizers. The fragmentable sensitizers are N-methoxyheterocycles that cleave a relatively weak N-O bond in either their reduced or excited forms. Sensitization mechanisms in both the singlet and the triplet manifolds are described. Irreversible oxidation of guanosine is demonstrated as an illustrative example.

AB - Irreversible photooxidation based on N-O bond fragmentation is demonstrated for N-methoxyheterocycles in both the singlet and triplet excited state manifolds. The energetic requirements for bond fragmentation are studied in detail. Bond fragmentation in the excited singlet manifold is possible for ππ* singlet states with energies significantly larger than the N-O bond dissociation energy of ca 55 kcal mol-1. For the nπ* triplet states, N-O bond fragmentation does not occur in the excited state for orbital overlap and energetic reasons. Irreversible photooxidation occurs in the singlet states by bond fragmentation followed by electron transfer. Irreversible photooxidation occurs in the triplet states via bimolecular electron transfer to the donor followed by bond fragmentation. Using these two sensitization schemes, donors can be irreversibly oxidized with oxidation potentials ranging from ca 1.6-2.2 V vs SCE. The corresponding N-ethylheterocycles are characterized as conventional reversible photooxidants in their triplet states. The utility of these sensitizers is demonstrated by irreversibly generating the guanosine radical cation in buffered aqueous solution. The return or reverse electron transfer that occurs in the primary charge-separated pair that is a feature of all photoinduced electron transfer reactions wastes energy and competes with useful chemistry in the charge-separated species. Here, we describe photoinduced electron transfer schemes that made irreversible by using fragmentable sensitizers. The fragmentable sensitizers are N-methoxyheterocycles that cleave a relatively weak N-O bond in either their reduced or excited forms. Sensitization mechanisms in both the singlet and the triplet manifolds are described. Irreversible oxidation of guanosine is demonstrated as an illustrative example.

UR - http://www.scopus.com/inward/record.url?scp=84896405212&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84896405212&partnerID=8YFLogxK

U2 - 10.1111/php.12227

DO - 10.1111/php.12227

M3 - Article

C2 - 24354634

AN - SCOPUS:84896405212

VL - 90

SP - 313

EP - 328

JO - Photochemistry and Photobiology

JF - Photochemistry and Photobiology

SN - 0031-8655

IS - 2

ER -