Spectroscopy and Kinetics of Singlet Perfluoro-4-biphenylnitrene and Singlet Perfluorophenylnitrene

Gritsan, Nina P.; Zhai, H. B.; Yuzawa, Tetsuro; Karweik, Dale H.; Brooke, J. J.; Platz, Matthew S.

doi:10.1021/jp963139y

Cited by 85 publications

(113 citation statements)

References 27 publications

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“…In some cases (e.g., singlet 2‐pyrimidylnitrene),55 the singlet nitrene species may decay mainly by intersystem crossing to the triplet nitrene species. The chemistry and reaction mechanisms of singlet phenyl nitrene has been extensively studied and well characterized 7, 8, 18, 20, 21, 42–46, 52–54. Singlet phenyl nitrene has been directly observed at room temperature44, 45 and has a short lifetime of ≈1 ns that is mainly caused by the fast ring‐expansion reaction ( E a =2–3 kcal mol −1 ).…”

Section: Introductionmentioning

confidence: 99%

SERS and Multiphoton‐Induced Luminescence of Gold Micro‐ and Nanostructures Fabricated by NIR Femtosecond‐Laser Irradiation

et al. 2008

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In contrast to almost non-luminescent bulk gold with a photoluminescence (PL) quantum yield of merely 10 À10 , [1] rod-shaped gold nanoparticles [2] as well as gold clusters consisting of only a few atoms [3,4] exhibit fascinating size-and shape-dependent luminescence properties with over one-million-times enhanced quantum yields. Furthermore, our group could show that gold nanoparticles embedded in glassy nanolayers show a bright multiphoton-induced (nonlinear) luminescence.[5] Although this phenomenon as such has been published in detail previously, [5] possible applications have not been reported so far. The described multiphoton-induced luminescence is indeed very promising due to the excitation of the light emission by nearinfrared (NIR) photons. The low tissue autofluorescence and the deep penetration depth of light waves into the tissues in the NIR spectral range make the particles excellent candidates for contrast reagents in the field of biological imaging. A second major advantage of using gold is that it is non-toxic and superior for bio-labeling as it can be easily functionalized with diverse compounds by the reaction with thiolates and other organic molecules. In addition, gold nanoparticles have attracted much attention in ex-vivo and in-vivo biological imaging due to the surface-enhanced Raman scattering (SERS) effect of adsorbed molecules. [6,7] For the utilization of gold nanoparticles as luminescence and SERS sensor materials and especially for trace analysis, a simple, fast and reproducible technique for the production of SERS-active and luminescent substrates is necessary. [8,9] Furthermore, the mean particle size, the size distribution and the spatial arrangement of nanoparticles must fulfill certain criteria for optimum SERS enhancement.[10] As an additional requirement for analytical applications the particles should be very stable towards any kinds of solvents. An ideal SERS-active substrate should be usable more than once since the analyte molecules can be washed away after the detection without damaging the substrate. Herein, we introduce an efficient and facile chemical sol-gel derived technique to generate gold nanoparticles in glassy silicate-titanium nanolayers by titaniumdoped sapphire (Ti:Sa) femtosecond(fs)-laser activation. Our new laser scanning microscope (LSM) and surface-electron microscopy (SEM) data support our previous findings and clearly demonstrate that well-defined micro-and nano-patterns of gold nanoparticles can be fabricated over extended areas on stable films by employing a confocal LSM, thus showing the ease and feasibility of this method for "real world" applications. This procedure is fast and straightforward. The partially embedded or tethered gold nanoparticles are stable and show a multiphoton NIR excited photoluminescence (PL). The PL is helpful for directly visualizing (or imaging) the gold nanostructures. It might become very useful for detecting reporter molecules in combination with SERS. Additionally, we show that the luminescent gold nanoparticle films...

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Section: Introductionmentioning

confidence: 99%

SERS and Multiphoton‐Induced Luminescence of Gold Micro‐ and Nanostructures Fabricated by NIR Femtosecond‐Laser Irradiation

et al. 2008

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“…Because most biomolecules are transparent to the wavelength required for the photolysis of a phenyl azide, various phenylnitrenes have proven useful as photoaffinity labels 16–28. To act as a label, the nitrene must covalently attach (by bond insertion) to the active site of the biomolecule with which it is complexed.…”

Section: Introductionmentioning

confidence: 99%

meta and para substitution effects on the electronic state energies and ring‐expansion reactivities of phenylnitrenes

Johnson

Sullivan

Cramer³

2001

Int J of Quantum Chemistry

151

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ABSTRACT:The electronic structures of the triplet ground states and first three excited singlet states for phenylnitrene, 14 meta-, and 17 para-substituted congeners have been characterized using density functional theory and multireference second-order perturbation theory (CASPT2). Ring expansion pathways to form didehydroazepines have activation enthalpies of about 9 kcal · mol −1 and are fairly insensitive to substitution-in the case of the strongest para donor, MeNH-, this barrier increases to about 13 kcal · mol −1 . The trends in state energies as a function of substitution are rationalized using a (2,2) configuration interaction theory and qualitative molecular orbital theory. Analysis of spin-orbit coupling in the nitrenes using the same model in conjunction with explicit calculation of spin-orbit coupling matrix elements rationalizes why electron donating substituents increase rates of intersystem crossing.

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“…This reaction has been studied for many years and several reaction pathways have been proposed to explain the products formed. The singlet state nitrene 2 is considered the first intermediate formed upon photolysis of phenyl azide and improved spectroscopic techniques have allowed direct observation of this short lived intermediate [10,14,15,21]. This singlet nitrene can undergo ring insertion to form a bicyclic azirine 5 or ring expansion to form a didehydroazepine 4 that can be trapped to give synthetically useful yields of azepine 7.…”

Section: Introductionmentioning

confidence: 99%

Photochemistry of fluorophenyl azides in aniline

Leyva

Sagredo

Moctezuma

2004

Journal of Fluorine Chemistry

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Spectroscopy and Kinetics of Singlet Perfluoro-4-biphenylnitrene and Singlet Perfluorophenylnitrene

Cited by 85 publications

References 27 publications

SERS and Multiphoton‐Induced Luminescence of Gold Micro‐ and Nanostructures Fabricated by NIR Femtosecond‐Laser Irradiation

SERS and Multiphoton‐Induced Luminescence of Gold Micro‐ and Nanostructures Fabricated by NIR Femtosecond‐Laser Irradiation

meta and para substitution effects on the electronic state energies and ring‐expansion reactivities of phenylnitrenes

Photochemistry of fluorophenyl azides in aniline

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