Publications
235 results found
AMBROZ M, BEEBY A, MACROBERT AJ, et al., 1991, PREPARATIVE, ANALYTICAL AND FLUORESCENCE SPECTROSCOPIC STUDIES OF SULFONATED ALUMINUM PHTHALOCYANINE PHOTOSENSITIZERS, JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY, Vol: 9, Pages: 87-95, ISSN: 1011-1344
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- Citations: 162
RUMBLES G, BROWN AJ, PHILLIPS D, 1991, TIME-RESOLVED EVANESCENT WAVE-INDUCED FLUORESCENCE SPECTROSCOPY .1. DEVIATIONS IN THE FLUORESCENCE LIFETIME OF TETRASULFONATED ALUMINUM PHTHALOCYANINE AT A FUSED-SILICA METHANOL INTERFACE, JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS, Vol: 87, Pages: 825-830, ISSN: 0956-5000
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- Citations: 29
VAUTHEY E, PHILLIPS D, 1990, VISCOSITY EFFECT ON THE RATE OF BACK ELECTRON-TRANSFER WITHIN A SHORT-LIVED EXCIPLEX, CHEMICAL PHYSICS, Vol: 147, Pages: 421-430, ISSN: 0301-0104
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- Citations: 19
BOUWMAN WG, JONES AC, PHILLIPS D, et al., 1990, FLUORESCENCE OF GASEOUS TETRAENES AND PENTAENES, JOURNAL OF PHYSICAL CHEMISTRY, Vol: 94, Pages: 7429-7434, ISSN: 0022-3654
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- Citations: 67
TAYLOR AG, JONES AC, PHILLIPS D, 1990, STRONG HYDROGEN-BONDING BETWEEN EXCITED-STATE CARBAZOLE AND TRIALKYLAMINES - A LASER-INDUCED FLUORESCENCE STUDY, CHEMICAL PHYSICS LETTERS, Vol: 169, Pages: 17-22, ISSN: 0009-2614
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- Citations: 16
PHILLIPS D, 1990, PHOTOPHYSICS, JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY, Vol: 51, Pages: 9-12, ISSN: 1010-6030
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- Citations: 2
CHAN WS, MACROBERT AJ, PHILLIPS D, et al., 1989, USE OF CHARGE COUPLED DEVICE CAMERA FOR IMAGING OF INTRACELLULAR PHTHALOCYANINES, PHOTOCHEMISTRY AND PHOTOBIOLOGY, Vol: 50, Pages: 617-624, ISSN: 0031-8655
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- Citations: 33
MacRobert AJ, Bown SG, Phillips D, 1989, What are the ideal photoproperties for a sensitizer?, Ciba Found Symp, Vol: 146, Pages: 4-12, ISSN: 0300-5208
For effective photosensitization of malignant tumours, a sensitizer should exhibit appreciable absorption at red to near-infrared wavelengths and generate cytotoxic species via oxygen-dependent photochemical reactions. These photosensitization mechanisms rely on the excitation of the sensitizer from its electronic ground state to the fluorescent singlet state, which is in turn transformed into the longer-lived triplet state. Efficient formation of this metastable state is required because it is the interaction of the triplet state with tissue components that generates cytotoxic species such as singlet oxygen. Measurement of fluorescence provides a useful means of probing the sensitizer, particularly because detection sensitivities for both the triplet state and the cytotoxic singlet oxygen are much lower. With the development of chemically well-defined sensitizers, in vivo fluorescence detection has the potential to provide quantitative assessment of photoactive sensitizer distributions. The reactive properties of sensitizer triplet states and species such as singlet oxygen can result in significant sensitizer photodegradation, which may appear undesirable but can be exploited in vivo under certain conditions.
Rughooputh SDDV, Bloor D, Phillips D, et al., 1988, Fluorescence studies of polydiacetylenes in 2-methyltetrahydrofuran vitreous glasses at low temperatures, Chemical Physics, Vol: 125, Pages: 355-373, ISSN: 0301-0104
Fluorescence emission from 2-methyltetrahydrofuran glasses containing two different polydiacetylenes has been studied over the range 4-250 K. The spectra are dependent on the thermal history of the glass and reveal the presence of different polymer chain species. The relaxation and transfer of excitation energy within these species has been studied by both steady state and time-resolved measurements. Localisation of the excitation energy in the tail of an inhomogeneously broadened excited state is observed at 4 K. The results are discussed in terms of current models for polydiacetylene chains in solution and the relationship between the species observed in glasses and possible precursor species in the initial solution is described. © 1988.
CHAN WS, MARSHALL JF, SVENSEN R, et al., 1987, PHOTOSENSITIZING ACTIVITY OF PHTHALOCYANINE DYES SCREENED AGAINST TISSUE-CULTURE CELLS, PHOTOCHEMISTRY AND PHOTOBIOLOGY, Vol: 45, Pages: 757-761, ISSN: 0031-8655
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- Citations: 47
Rughooputh SDDV, Bloor D, Phillips D, et al., 1987, One-dimensional exciton diffusion in a conjugated polymer, Physical Review B, Vol: 35, Pages: 8103-8112, ISSN: 0163-1829
One of the most interesting questions in modern transport theory has been and still is the following: What is the influence of dimensionality (including fractal) on the carrier and exciton dynamics and decay kinetics in quasiordered and disordered systems. An enormous amount of theoretical work has been done in this field, extended now to include direct computer simulations. Experimental data have been more difficult to find and are consequently sparse and not always convincing. Certain types of organic compounds and, in particular polydiacetylenes, constitute unique classes of nearly one-dimensional systems. Studies including photoconductive decays have been extended to include picosecond luminescence decay on PDA-1OH [poly(diacetylene-1-hydroxy-hexadyine- diol)], a continuous highly oriented fibrous polymer. The decay laws are compared with exact results in dimensionalities d=1 and near 1. The present data together with the recent work on doped tetramethylammonium manganese trichloride may be evidence for the first time of one-dimensional exciton motion. © 1987 The American Physical Society.
CHAN WS, SVENSEN R, PHILLIPS D, et al., 1986, CELL UPTAKE, DISTRIBUTION AND RESPONSE TO ALUMINUM CHLORO SULFONATED PHTHALOCYANINE, A POTENTIAL ANTITUMOR PHOTOSENSITIZER, BRITISH JOURNAL OF CANCER, Vol: 53, Pages: 255-263, ISSN: 0007-0920
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- Citations: 112
McCubbin I, Phillips D, 1986, The photophysics and photostability of zinc(II) and aluminium(III) sulphonated naphthalocyanines, Journal of Photochemistry, Vol: 34, Pages: 187-195, ISSN: 0047-2670
The photophysical properties of aluminium(III) and zinc(II) sulphonated naphthalocyanines have been compared with those of the corresponding metallophthalocyanines, leading to the conclusion that the former class of compounds may be useful as sensitizers in certain applications. A comparison of the relative stability of aluminium phthalocyanine and aluminium naphthalocyanine indicated that the latter compound is significantly less stable to photo-oxidation. © 1986.
Rughooputh SDDV, Phillips D, Bloor D, et al., 1985, Spectroscopic studies of polydiacetylene solutions and glasses. Glasses of a hydrogen-bonding polymer, Chemical Physics Letters, Vol: 114, Pages: 365-370, ISSN: 0009-2614
In this communication we report some electronic spectral studies on a soluble polydiacetylene: poly[4,6-decadiyne-1,10-bis-(butoxycarbonyl methylene urethane)], 4BCMU. The results obtained are comparable to our previous studies on another soluble polydiacetylene: poly[10,12-docosadiyne-1,22-bis-(phenyl acetate)], 9PA. The essential difference between these two systems is that 4BCMU contains sidegroups capable of forming hydrogen bonds parallel to the polymer chain whereas the 9PA sidegroups cannot. © 1985.
Rughooputh SDDV, Phillips D, Bloor D, et al., 1984, Spectroscopic studies of polydiacetylene solutions and glasses, Chemical Physics Letters, Vol: 106, Pages: 247-251, ISSN: 0009-2614
Absorption, fluorescence excitation and emission spectra of a soluble polydiacetylene, obtained by the solid-state polymerization of the bis-(phenyl acetate) ester of 10,12-docosadiyne-1. 22-diol, have been recorded at room and liquid-nitrogen temperatures for different solvents. Spectral shifts, similar to those reported for other soluble polydiacetylenes, are observed on addition of a non-solvent or on cooling the solutions. The fluorescence quantum yield was measured from 2-methyl tetrahydrofuran solution at room temperature. The yield, was roughly one hundred times larger for this system at 77 K and well-structured fluorescence spectra were observed for this low-temperature glass. © 1984.
Mijovic MV, Beynon PJ, Shaw TJ, et al., 1982, Cross-Link Formation in a Solid Photopolymer Based on the Chromophore 1,2-Diphenylcyclopropene, Macromolecules, Vol: 15, Pages: 1464-1471, ISSN: 0024-9297
The absolute quantum yield of cross-link formation in a photopolymer based on the photoreactive chromophore 1,2-diphenylcyclopropene (CP) approaches the theoretical maximum for a single-step cross-linking process. In the matrix, only a small fraction of chromophores (∼4%) are in reactive configurations, and it appears from the fluorescence behavior of the films that these are associated with excimers. Chemical analysis reveals the formation of tricyclic dimers in the irradiated films, as anticipated by DeBoer et al.,2,3 which indicates that the primary cross-linking step is cycloaddition between the double bonds of two suitably oriented cyclopropene rings. The high initial quantum yield of the photoreaction coupled to a low concentration of reactive sites implies extensive energy migration in the system. From lifetime measurements, the migration range of the triplet excitation in the matrix is estimated at 150 Å. © 1982, American Chemical Society. All rights reserved.
Graley M, Reiser A, Roberts AJ, et al., 1981, Excimer Fluorescence as a Probe into the Solution Behavior of a Polyester of p-Phenylenediacrylic Acid, Macromolecules, Vol: 14, Pages: 1752-1757, ISSN: 0024-9297
A polyester of p-phenylenediacrylic acid (PPDA) and the small-molecule model diethyl pphenylenediacrylate (Et2PDA) show monomer and excimer fluorescence in solution. The kinetics of fluorescence decay indicate ground-state interaction between PDA groups in both systems. Excimers arise here not via the usual bimolecular quenching mechanism but by the excitation of preformed chromophore pairs. As a consequence, in solutions of PPDA, the quantum yield of excimer fluorescence measures directly and in absolute terms the number of intersegmental contacts of the polymer chain. In the isolated PPDA molecule on average every fourth chromophore takes part in an intermolecular contact; with increasing polymer concentration the contact frequency increases and intramolecular contacts are replaced by intermolecular ones. In that way, the state of aggregation which is responsible for the photochemical, and the photographic, behavior of the solid matrix is preformed in solution, in response to a weak ground-state interaction between PDA groups. © 1981, American Chemical Society. All rights reserved.
Phillips D, Roberts AJ, Soutar I, 1981, Transient decay studies of photophysical processes in aromatic polymers: 4. Intramolecular excimer formation in homopolymers of 1-vinylnaphthalene, 2-vinylnaphthalene and 1-naphthyl methacrylate, Polymer, Vol: 22, Pages: 427-429, ISSN: 0032-3861
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- Citations: 28
Majer JR, Phillips D, 1969, Photolysis of perfluoro-alicyclic ketones, Journal of the Chemical Society B: Physical Organic, Pages: 201-203, ISSN: 0045-6470
Photolysis in the gas phase of perfluorocyclo-pentanone, -hexanone, -heptanone, and-octanone at 3130 Å is reported. Migration of fluorine atoms is not observed, and in the case of the pentanone and hexanone, the only products observed were carbon monoxide and a cyclic fluorocarbon. From perfluorocycloheptanone, perfluorocyclohexane, carbon monoxide, perfluoracyclopentane, and tetrafluoroethylene were the photolysis products. Photolysis of the perfluorocyclo-octanone gave rise to perfluorocycloheptane, carbon monoxide, perfluorocyclohexane, perfluorocyclopentane, and tetrafluoroethylene. A mechanism involving diradical intermediates is proposed.
Phillips D, 1967, Triplet-state yield of fluorobenzene by the sensitization of the isomerization of cis-butene-2, The Journal of Physical Chemistry, Vol: 71, Pages: 1839-1841, ISSN: 0022-3654
Triplet-state yields for fluorobenzene excited at 2650, 2537, and 2480 A, respectively, have been determined. The plots all lie on the same smooth curve of quantum yield vs. cis-butene-2 pressure, thus indicating that a common level is reached before crossover from excited singlet to triplet state. The asymptotic value for the triplet yield is 0.86 at high pressures of cis-butene-2. The sum of triplet state and fluorescent yields is about 1.05 ± 0.09. Comparison with other results is made.
Phillips D, 1967, Fluorescence and triplet state of hexafluorobenzene, The Journal of Chemical Physics, Vol: 46, Pages: 4679-4689, ISSN: 0021-9606
The photochemistry of hexafluorobenzene in the vapor phase has been studied to compare the heavy-atom substituted molecule with the unsubstituted molecule of the same symmetry. Results show that at all wavelengths below 2800 Å, absorption produces two excited singlet states, one of which is quickly equilibrated to a fluorescent state, the other more slowly. Some process occurs from the latter state with a rate such that collisional loss of energy is barely competitive. This process may be an isomerization. The use of the biacetyl sensitization and Cundall techniques at various wavelengths indicated that the lifetime of the hexafluorobenzene triplet was short, and of the order of 10 -7 sec leading to difficulties in absolute measurement of the triplet-state yields. The quenching of biacetyl phosphorescence excited by 4358-Å radiation by hexafluorobenzene is observed, and the effect of exciting wavelength upon the fluorescence yields of hexafluorobenzene is discussed. A simple mechanism has been proposed and rate constants and quenching cross sections calculated.
Phillips D, 1966, Photolytic processes in perfluorocyclobutanone vapor, Journal of Physical Chemistry, Vol: 70, Pages: 1235-1243, ISSN: 0022-3654
The photolysis of perfluorocyclobutanone in the vapor phase at 3130, 3340, 3660, and 4047 A has been investigated. Fluorescence and decomposition yields have been determined at the four wavelengths and the effects of pressure and temperature upon them studied. Two modes of decomposition occur at the shortest wavelengths and at high temperatures, one producing carbon monoxide and perfluorocyclopropane, the other producing tetrafluoroethylene. A mechanism is proposed which explains the results, and rate constants for reactions are determined. Results indicate that about 7 kcal mole-1 excess vibrational energy can be removed from the excited ketone by each collision with an unexcited ketone molecule.
Majer JR, Phillips D, Robb JC, 1965, Photodecomposition of halogenated ketones: Part 3. - Addition of CF <inf>2</inf>Cl radicals to aromatic compounds, Transactions of the Faraday Society, Vol: 61, Pages: 110-121, ISSN: 0014-7672
1,3-Dichlorotetrafluoroacetone has been photolyzed with light of wavelength 3130 Å in the presence of benzene and hexafluorobenzene. The activation energy for the addition of CF2Cl radicals to benzene is 5.3±0.4 kcal mole-1 and that for addition to hexafluorobenzene, 2.4±0.4 kcal mole-1. The addition complex formed between CF2Cl and benzene is believed to decompose at higher temperatures before further reaction takes place. The energy of activation for the decomposition process is estimated as 11.4±0.8 kcal mole -1, and D(C6H6-CF2Cl) to be 6.1 ± 0.5 kcal mole-1.
Majer JR, Phillips D, Robb JC, 1965, Photodecomposition of halogenated ketones: Part 4. - Reaction of CF <inf>2</inf>Cl radicals with cyclopentane, Transactions of the Faraday Society, Vol: 61, Pages: 122-128, ISSN: 0014-7672
1,3-Dichlorotetrafluoro acetone has been photolyzed in the presence of cyclopentane and the quenching efficiency of the hydrocarbon for excited ketone molecules compared with that of C5F10, C6H 6 and C6F6. The CF2Cl radicals formed by photolysis, abstract hydrogen from cyclopentane and the energy of activation for this process is 5.3 kcal mole-1. This reaction has been compared with that of addition to C6H6 and C 6D6 and the ratio kabs.(C5H 10)/kaddn.(C6H6) found to be 0.38. The activation energy for the thermal decomposition of the adduct formed between CF2Cl radicals and C6D6 is 11.2 kcal mole -1.
Majer JR, Phillips D, 1964, Disproportionation of halogenated alkyl radicals [12], Nature, Vol: 203, Pages: 1165-1167, ISSN: 0028-0836
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- Citations: 2
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