Organic Chemistry in Colour

Gordon, P. F.; Gregory, P. J.

doi:10.1515/9783112541746

Cited by 263 publications

(45 citation statements)

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“…The electron density for HOMO and LUMO of each species is shown in Figure 8. The calculated electron density of HOMO-LUMO transition for DO11 agrees with the computational results for aminoanthraquinones in the literature [60,63]: the amine group is the principal electron donor of the ICT, and the electron acceptors include both carbonyl groups, the center ring and the unsubstituted ring. However, while the amine group remains the principal electron donor of the ICT for all reversibly-and irreversibly-damaged species, the carbonyl group adjacent to the amine group loses its electron accepting ability even though the other electron acceptors are unchanged in their electron accepting ability.…”

Section: Computational Resultssupporting

confidence: 82%

“…The calculated electron density of 1AAQ is also observed to increase in the unsubstituted ring and in the carbonyl groups in the first excited state relative to the ground state [60]. This indicates that the carbonyl groups are not the only electron acceptors [60]. This observation is consistent with the results reported by Inoue et al that the calculated electron density of 1AAQ of the first excited state is increased in the carbonyl groups, the center ring and the unsubstituted ring, though they only mentioned the carbonyl groups [63].…”

Section: Introductionmentioning

confidence: 89%

“…For example, DO11 dissolved in MMA is observed to show an absorption peak at 471 nm with an extinction coefficient of 8.043 × 10 3 cm -1 M -1 . The calculated electron density of 1AAQ is also observed to increase in the unsubstituted ring and in the carbonyl groups in the first excited state relative to the ground state [60]. This indicates that the carbonyl groups are not the only electron acceptors [60].…”

Section: Introductionmentioning

confidence: 93%

“…Several hypotheses of the mechanism responsible for reversible photodegradation in DO11/PMMA have been proposed, including intramolecular proton transfer and dimer formation [46], twisted intramolecular charge transfer [55], and domain-assisted reversible photodegradation [51,56,57], none have been experimentally proven. These hypotheses, together with anion formation [58,59] and protonation [60,61] of dye molecules observed in similar systems, have been investigated and the results suggest that they are unlikely responsible for reversible photodegradation of 1-substituted aminoanthraquinone derivatives doped in PMMA and PS [49].…”

Section: Introductionmentioning

confidence: 98%

“…Anthraquinone exhibits a weak optical absorption band at 405 nm [60,62], with an extinction coefficient about 60 cm -1 M -1 (in methanol) which is often undetected [60]. Aminoanthraquinones, however, possess moderate to strong absorption bands in the visible regime, which are absent in anthraquinone, and have been assigned to intramolecular charge transfer (ICT) between the amine group and the carbonyl groups [63,64].…”

Section: Introductionmentioning

confidence: 99%

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Spectroscopic studies of the mechanism of reversible photodegradation of 1-substituted aminoanthraquinone-doped polymers

Hung

Bhuyan

Schademan

et al. 2016

The Journal of Chemical Physics

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The mechanism of reversible photodegradation of 1-substituted aminoanthraquinones doped into poly(methyl methacrylate) and polystyrene is investigated. Time-dependent density functional theory is employed to predict the transition energies and corresponding oscillator strengths of the proposed reversibly-and irreversibly-damaged dye species. Ultraviolet-visible and Fourier transform infrared (FTIR) spectroscopy are used to characterize which species are present. FTIR spectroscopy indicates that both dye and polymer undergo reversible photodegradation when irradiated with a visible laser. These findings suggest that photodegradation of 1-substituted aminoanthraquinones doped in polymers originates from interactions between dyes and photoinduced thermally-degraded polymers, and the metastable product may recover or further degrade irreversibly. INTRODUCTIONOrganic materials have a broad range of applications such as high-resolution fluorescence microscopy [1][2][3][4][5][6][7], second harmonic generation (SHG) microscopy [8][9][10][11][12], dye sensitized and polymer solar cells [13][14][15][16][17], solid state dye/organic lasers [18][19][20], and organic light emitting diodes [21,22], to name a few. Photostability of organic compounds and polymers is often a requirement for applications incorporating light-matter interaction [2-4, 6, 8, 18-20, 23-30]. When a material undergoes photodegradation, its characteristic properties deteriorate over time, which is referred to as decay; the reverse change in the characteristic properties of the material is referred to as recovery. Though photodegradation is often irreversible, the recovery process has been observed from a large variety of materials, typically involving polymers and often together with dyes, with various experimental techniques when the photodegraded materials are kept in dark for a long enough time, typically hours to days [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44].Amplified spontaneous emission (ASE) of disperse orange 11 (DO11) doped in poly(methyl methacrylate) (PMMA) bulk sample was observed to fully recover in the dark about 40 hours after photodegradation when irradiated with a 532 nm second harmonic Nd:YAG picosecond laser [33]. This self-healing phenomenon was also observed in various anthraquinone derivatives doped in PMMA and polystyrene (PS) thin films [41,42] and DO11 doped in MMA-styrene copolymers thin films [42,45] probed with transmittance image microscopy and ASE. The photodegraded thin film samples are often observed to recover partially, which suggests there exists both reversible and irreversible photodegradation. The lack of evidence for linear dichroism during photodegradation measurements eliminates orientational hole burning as the mechanism causing reversible photodegra- [38,42,46,[50][51][52][53][54], they have failed to elucidate the underlying mechanism.Several hypotheses of the mechanism responsible for reversible photodegradation in DO11/PMMA have been proposed, including intramolecular proton transfer and ...

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Section: Computational Resultssupporting

confidence: 82%

Section: Introductionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Spectroscopic studies of the mechanism of reversible photodegradation of 1-substituted aminoanthraquinone-doped polymers

Hung

Bhuyan

Schademan

et al. 2016

The Journal of Chemical Physics

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Vascular permeability in the peripheral autonomic and somatic nervous systems: Controversial aspects and comparisons with the blood-brain barrier

Kiernan

1996

Microsc. Res. Tech.

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Endothelium, choroidal epithelium, and arachnoid exclude plasma proteins from most parts of the mammalian central nervous system (CNS). Nerve roots, in contrast, have permeable capillaries and permeable pia‐arachnoid sheaths. Diffusion of plasma proteins into the cerebrospinal fluid is probably prevented by slow bulk flow along a pressure gradient from the subarachnoid space into the veins of the roots. In nerves, the perineurium prevents diffusion of proteins from the epineurium into the endoneurium. Capillaries within fascicles are permeable to macromolecules, though less so than the microvessels of roots and ganglia. Endoneurial vascular permeability is lowest in rats and mice, but even in these species albumin is normally present in the extracellular spaces around the nerve fibers. The so‐called blood‐nerve barrier is not equivalent to the blood‐brain barrier. Capillaries in sensory and sympathetic ganglia are fully permeable to macromolecules, and extravasated protein is in contact with neuronal cell bodies and neurites. An impenetrable perineurium surrounds each ganglion, but serves no obvious purpose when the vessels inside are as permeable as those outside. The enteric nervous system lacks a perineurium, and the neurons in its avascular ganglia and tracts are exposed to extracellular fluid formed by permeable vessels in adjacent tissues of the gut. The reasons for excluding macromolecules from some parts of the nervous system are obscure. Carrier‐mediated transport, which maintains a constant supply of ions, glucose, and other metabolites to cells in the CNS, would be impossible if larger molecules could diffuse freely. Presumably the metabolic needs of ganglia are adequately met by exchange vessels similar to those of nonnervous tissues. Most of the CNS is protected from exogenous toxic substances that bind to plasma proteins. Peripheral neurons and glial cells are damaged by some such substances because of the lack of blood‐tissue barriers. © 1996 Wiley‐Liss, Inc.

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Absorption maxima study of chromophores of indigoid dyes

Chen

1996

Int. J. Quantum Chem.

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rnMolecular structure of 21 chromophores of indigoid dyes were studied by an ab initio MP2/6-31 + G*//HF/6-31 + G* method. Bond lengths and bond angles were affected by r-electron conjugation. The difference between molecular structures of chromophores and indigoid dyes indicated that benzene rings and five-membered rings in indigoid dyes are structurally important. Absorption maxima of chromophores were successfully calculated by the CI-singles-MP2/6-31 + G* theory. Like indigoid dyes, absorption maxima of the chromophores are affected by the positions of the donor and acceptor groups on the trimethine group. Bathochromic shifts of the absorption maxima were observed with the best donor group of -NH among -NH, -0, and -S groups. Appropriate substitution of longer-chain polymethines brought about chromophoric systems having hypsochromic shifts. From these calculations, the absorption maxima of some indigoid dyes could be explained by their chromophores qualitatively.

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Organic Chemistry in Colour

Cited by 263 publications

References 0 publications

Spectroscopic studies of the mechanism of reversible photodegradation of 1-substituted aminoanthraquinone-doped polymers

Spectroscopic studies of the mechanism of reversible photodegradation of 1-substituted aminoanthraquinone-doped polymers

Vascular permeability in the peripheral autonomic and somatic nervous systems: Controversial aspects and comparisons with the blood-brain barrier

Absorption maxima study of chromophores of indigoid dyes

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