Photofading Rate Research Articles

Effect of nickel arylsulfonates on the photofading of dyes in polymer substrate.

ABSTRACT: Various nickel salts have been synthesized, and their protecting effects on photofading of Orange I (C. I. Acid Orange 20), Rose Bengal (C. I. Acid Red 94), Crystal Violet (C. I. Basic Violet 3) and Eosine (C. I. Acid Red 87) were examined in cellulose acetate film with carbon arc Fade Ometer. The rates of photofading of the dyes were remarkably suppressed in the presence of nickel salts, while the addition of UV absorber afforded little retardation of the rate of fading. The effects of combined use of nickel salt and UV absorber on the photostability of dyes were also examined.

Mechanisms and Rate Constants for the Quenching of Singlet Oxygen by Nickel Complexes

Abstract An iterative numerical determination of the rate constants for both quenching of, kq, and reaction with, kr, singlet oxygen by dithiolato nickel complexes is developed. This numerical method gives accurate rate constants for a small number of kinetic runs. The substituent effects of these complexes on rate constants lead us to conclude that the complexes quench singlet oxygen by an energy-transfer mechanism. This numerical method developed for solution systems was applied to the estimation of the photofading rate of a cyanine dye on an epoxy resin plate.

Influence of acid dyes on the photo-oxidation of nylon 6,6 film: relationship with rate of photofading and luminescent species

The photofading rates of three azo acid dyes (C.I. Acid Blue 62, C.I. Acid Yellow 135 and C.I. Acid Red 266) and four azo acid metal complex dyes (C.I. Acid Brown 266, C.I. Acid Blue 171, C.I. Acid Orange 162 and C.I. Acid Black 107) were examined in nylon 6,6 film and were compared with the influence of the dyes on the photochemical degradation of the polymer using UV—visible absorption and viscometric analysis. For the first three acid dyes, the relative rates of photofading correlate with the ability of the dyes to photostabilize the polymer, i.e. yellow > blue > red. However, all the dyes are more photostable than the polymer. The acid metal complex dyes also photostabilize the polymer in the order blue > black > orange > brown. The nature of the central metal atom is concluded to be an important factor. In the presence of the dyes the concentration of terminal amine groups has little influence on polymer stability, but dye bath treatment improves the photostability of the polymer due to extraction of photoactive impurities. There is a close correlation between the ability of the dyes to quench the luminescent chromophores and polymer stability; the ability to quench the phosphorescent species at 290 400 nm is most significant as indicated by the correlation coefficients. This suggests that triplet energy transfer may be important in stabilization of the polymer by the dye.

Photofading Rate of Disperse Dyes in Acetate and Nylon 6

We investigated the photofading behavior of CI disperse red 17 and CI disperse violet 1 in nylon 6 and red 17 in cellulose diacetate. The photofading rate of red 17 in nylon 6 was influenced by the concentration distribution in the film. The laminated film exposure method was applied to all systems, and the results indicate that the time required to reach a certain fading percentage increases exponentially with the film thickness. We assumed that the fading on the surface of the samples occurred in the first order of the dye concentration for the red 17-nylon 6 and violet 1-nylon 6 system, but in the zero-order process for the red 17-acetate system.

Photofading of Azo Pyridone Dyes in Solution

We report on the investigation and kinetic measurements of the photofading process of some o-, p-substituted azo pyridone dyes in formamide, N,N-dimethylformamide, and N,N'-dimethylacetamide. The free energies of solvation of dyes in the three solvents have been calculated by measuring the distribution coefficients of the dyes between the amide solvent and n-hexane as the immiscible standard solvent. A fair linear correlation exists between the observed rate constant and the free energies of transfer, suggesting the possibility that the photofading rate increases with increasing solvation of dyes; moreover it is increased by two electron-withdrawing substituents.

Effect of hydroxybenzophenone derivatives on the photofading of some dyes.

Nickel salt of 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (MS-Ni) and its derivative (DS-Ni), benzophenone type UV absorber containing singlet oxygen quenching group, have been synthesized and its effects were examined on the photofading of some dyes in solution and on a solid with a UV irradiation. The rates of photofading of indigoid dye (C. I. Vat Blue 1), anthraquinonoid dye (C. I. Disperse Red 15) and azo dye (C. I. Acid Orange 20) were remarkably retarded in the presence of MS-Ni or DS-Ni not only in solution but also in a solid state, but that of Eosine (C. I. Acid Red 87) on a solid was suppressed scarcely. The effects of added Nickel p-toluenesulfonate and 2, 6-di-t-butylphenol on the photo-stability of dyes were also examined.

The effect of polymers having ultraviolet absorptive groups on photofading rate of disperse dyes.

The effect of polymers having ultraviolet absorptive groups on photofading rate of disperse dyes.

THE EFFECT OF POLYMERS HAVING ULTRAVIOLET ABSORPTIVE GROUPS ON PHOTOFADING RATE OF ACRIDINE ORANGE N

The photofading of Acridine Orange N in a dioxane-ethanol mixture has studied in the presence of polymers having ultraviolet absorptive groups. The results were compared with the measurements made in the presence of the coresponding ultraviolet absorptive molecules. The polymers used were: CMPT prepared by the reaction of 32.4% chloromethylated polystyrene (CMPSt), with 2-(2′, 4′-dihydroxyphenyl) benzotriazole, and CMPB prepared by the reaction of CMPSt with 2, 4-dihydroxybenzophenone. CMPT contained 4.5% 2-(2′-hydroxyphenyl) benzotriazole (HBT) unit and 27.9% chloromethylstyrene (CMSt) unit and the rest 67.6% styrene (St) unit. CMPB contained 5.1% 2-hydroxybenzophenone (HBP) unit, 27.3% CMSt and the rest % St unit. The corresponding molecules used were 2-(2′-hydroxy-4′-methoxyphenyl)benzotriazol (HMBT) and 2-hydroxy-4-methoxybenzophe none (HMBP).In the case of irradiation with light of overall wavelengths under Xenon-arc lamp, CMPT and CMPB did not act as retarder for the photofading of Acridine Orange N in the solution, CMSt unit in these polymers underwent photochemical solvolysis in the solution to afford free HCl, which showed an accelerating action on the photofading rate of the dye. On the other hand, in the case of irradiation with light above 290nm, to which CMSt is insensitive, the effects of CMPT and CMPB were similar to HMBT and HMBP; these worked as retarder on the photofading in the order: CMPT>HMBT>CMPB>HMBP.HBT and HBP groups acted as both quencher and screener. The quenching effect was dominant under the low concentration of these additives, and the screening effect predominated under the high concentration of the additives.

THE EFFECT OF POLYMERS HAVING ULTRAVIOLET ABSORPTIVE GROUPS ON PHOTOFADING RATE OF ACRIDINE ORANGE N

The photofading of Acridine Orange N in dioxane-ethanol mixture has been studied in the presence of copolymers having 2-hydroxybenzophenone (HBP) group as a ultraviolet absorptive group on the polymer side-chain, 2-hydroxy-4-(3-methacryloxy-2-hydroxypropoxy)-benzophenone (BPMA) homopolymer, polystyrene (PSt), polymethyl methacrylate (PMMA) and 2-hydroxy-4-methoxybenzophenone (HMBP).PSB was obtained by copolymerization of styrene (St) with BPMA, and PMB also obtained by copolymerization of methyl methacrylate with BPMA. PSB contained St unit (main-chain) and HBP unit (8.9_??_14.2%), and PMB contained MMA unit (main-chain) and HBP unit (3.7_??_7.2%), while BPMA homopolymer (PBPMA) contained 100% HBP unit.The results of photofading of Acridine Orange N in the solutions containing these polymers or DHBP are summarised as follows. PSB, PMB, PBPMA and HMBP played roles of retarder on the photofading rate of the dye, with the effects in the following order: PSB>PBPMA>HMBP>PMB.A slight retardation effect was also observed with PSt, while PMMA acted as an accelerator. From these results it is reasonably concluded that the differences in the dye protective behaviors for light between PSB and PMB must be associated with the structural features, in particular, in the main-chain of these polymers.The fading of the dye was more marked with light in the wavelength region of 300_??_400nm than in the wavelengths >400nm, and the retarding action of HBP group was remarkably observed with 300_??_400nm light.Stern-Volmer plot (see Fig. 5) showed that HBP group acts as quenchers in the case of the low concentration of these additives.

Light stability and flash photolysis of azo dyes in epoxy resins

The photofading of three azo dyes is examined in various epoxy resin films and the data compared with their photochemical behaviour on flash photolysis in solutions of the resin components. The rate of photofading is found to be mainly dependent upon the structure of the amine hardener and the results are correlated with hydrazyl radical production on solution flash photolysis. Evidence is presented to show that photoreduction is the most important primary photochemical process for azo dyes in epoxy resin films.

Photofading Kinetics and Thermodynamics of Some Azo Disperse Dyes in Amide Solvents under the Influence of Far Ultra–violet Radiation

The paper reports some kinetic measurements of photofading of some 4′‐substituted 4–diethylaminoazobenzenes in formamide, N–methy/formamide, N, N–dimethy/formamide, N–methylacetamide and N, N–dimethyiacetamide. The observed Hammett p–values suggest a reductive pathway, as confirmed by the presence of anilines among the fading products. The free energies of solvation of the dyes in the various solvents have also been calculated by measuring the distribution coefficients of the dye between the amide solvent and n–hexane, as immiscible standard solvent. A fair linear correlation exists between the observed rate constants and the free energies of transfer, suggesting the possibility that photofading rate increases with increasing solvation of dye.

THE EFFECT OF POLYMERS HAVING ULTRAVIOLET ABSORPTION GROUPS ON PHOTOFADING RATE OF ACRIDINE ORANGE N

The photofading rate of Acridine Orange N in a dioxane-ethanol mixture has been studied in the presence of polymers having certain ultraviolet absorption groups, 2-hydroxybenzophenone (HBP), 2, 4-dihydroxybenzophenone (DHBP) and phenyl benzoate (PB).Polymer K was obtained from styrene-4-benzoxystyrene copolymer (polymer E) by Photo-Fries rearrangement. Polymer SB was obtained by copolymerization of styrene and 2-hydroxy-4-(3-methacryloxy-2-hydroxypropoxy) benzophenone (BPMA). Since the conversion of photo-Fries rearrangement of polymer E was low, polymer K contained a small fraction of HBP unit and a large fraction of PB unit as ultraviolet absorption groups, while polymer SB contained only HBP unit.The results of photofading of Acridine Orange N in the solutions containing these polymers are summarised as follows. Polymer K, polymer SB, HBP and DHBP played roles of retarder on the photofading rate of the dye with the extents of the effects in the order: polymer SB>DHBP>HBP>polymer K, while polymer E and PB acted as accelerator.

The contribution of singlet oxygen to the photofading of triphenylmethane and related dyes

The contribution of singlet oxygen ( 1 Δ gO 2) to the photofading of Crystal Violet in some solvents is examined. The rates of photofading in dichloromethane or acetone are accelerated in the presence of singlet oxygen sensitizers, e.g. Methylene Blue. The rates are retarded by adding effective singlet oxygen quenchers such as β-carotene or nickel dimethyldithiocarbamate. It seem shtat Crystal Violet is mainly photooxidized to give Michler's ketone and p-dimethylaminophenol via the reaction with singlet oxygen, which can be generated by the dye itself or by an added sensitizer. The effect of various singlet oxygen quenchers on the photostability of coloured materials derived from colour formers, such as Crystal Violet Lactone and 3-diethylamino-6-methyl-7-anilinofluoran, is examined also on silica gel.

Cycloheptaamylose-dansyl chloride complex as a fluorescent label of surface membranes in living ciliates.

Labelling of surface membrane of living ciliates: Paramecium aurelia and Tetrahymena pyriformis with fluorescent compound--cycloheptaamylose-dansyl chloride complex (CDC) has been achieved. Fluorescence micrographs of the dried samples showed specific localization of CDC on the cell membrane without any intracellular penetration. On the contrary the ciliates which have been dead during labelling revealed a non-specific fluorescence of their whole bodies. Microspectrofluorimetric analysis of labelled Paramecium cells was performed with Leitz microspectrograph. Spectrum of fluorescence emission measured over the cell membrane level had maximum at 450 nm. Strikingly, the emission maximum of the cells dead at the moment of labelling was shifted 10 nm to a longer wavelength. The rate of photofading measured in this case was almost 3-fold higher than for the ciliates labelled as living ones. Fluorescence excitation spectra did not show any difference in the peak position. Thus CDC staining appears to be an useful method of supravital labelling of cell surface enabling also to distinguish--on the basis of spectral characteristics--the ciliates being alive from those dead at the moment of fluorochrome binding.

EFFECTS OF ULTRAVIOLET ABSORBERS ON THE PHOTOFADING RATE OF ASTRAZON ORANGE G

The photofading rate of Astrazon Orange G in a dioxane-ethanol mixture has been studied in the presence of polymers having certain ultraviolet absorption groups, o-hydroxybenzophenone (HBP) and phenyl benzoate (PB) (polymer K and polymer E respectively).Polymer K and HBP show emission maxima at 495 and 470 nm, respectively and Astrazon Orange G has λmax, at 503 nm. Therefore, it is expected that energy transfer from such ultraviolet absorbers to Astrazon Orange G may occur, and hence the absorbers act as an accelerator on the photofading rate of the dye.The effects of the absorbers, found by the rate measurements, are summarized as follows:(1) Polymer K and HBP act as retarder, while polymer E and PB act as accelerator.(2) The energy transfer from HBP group to the dye does not occur; Stern-Volmer plot (Fig. 9) shows that HBP group acts as quencher.

ACYLATION OF STYRENE-ρ-HYDROXYSTYRENE COPOLYMER AND THE EFFECT OF ACYLATION PRODUCTS ON THE PHOTOFADING RATE OF METHYLENE BLUE

Styrene-ρ-hydroxystyrene copolymer was acylated with benzoyl chloride, o-methoxybenzoyl chloride, salicylic acid and 3-hydroxy-2-naphthoic acid. The structures of the acylated products have been identified by means of IR and UV spectroscopies.Methylene Blue in dioxane-ethanol solution containing the above acylated products or polystyrene was exposed to a xenon-arc lamp. The photofading rate of the Methylene Blue was calculated from the changes in the visible absorption spectra. The acylated products having an aromatic ester acted as a retarder on the rate, while polystyrene showed an accelerating action. The retarding action of the acylated products might be explained by the Photo-Fries rearrangement during the photofading of Methylene Blue.

The Effects of Fluorescent Brightening Agents on the Photofading of Blue Acid Azo Dyes

Blue acid azo dyes (AB 92, AB 116, ABk 1 and AG) have been irradiated with monochropa. atic lights of various wavelengths, and the influences of flurescent brightening agentsts of stilbene (FBg) and pyrazoline type (FwG) on the photofading have been investigated.The light from visible near ultraviolet region gave rise to s1ight fading of dyes. The rates of photodegradation increased sharply on irradiation with the light at the wave length shorter tAan 300Tnm. lrradiation with 252 nm light gave the quantum yield of 3x10dNl, 1x10ews for the air saturated solution. The fluorescent agents faded to a certain extent by the irradiation with the light of the 300-400nm region where the fluorescence had the excitation maximal and the rate of photofading was more rapidly at shorter wavelength. Dissolved oxygen depressed the degradation of the dyes and accelerated that of FwGiT-heVfluorescent'agents'quenched the photofading reaction of thedyes when they were applied without oxygen. Oh the other hand, acceleration of the reaction was observed'.in thg.air sa.tur rated solutfoWn. The acceleration effects were most prominent on 300At400 nm, irradiation(cf.Figs. 5 and 6). The effect of Fwo was three times as strong as FBs. IMTdshe Effects of Fluorescent substances en the phetofading of Celers. 1.

PHOTO-FADING OF 1, 4-DIAMINOANTHRAQUINONE IN THE AQUEOUS SOLUTIONS OF SURFACTANTS

In order to investigate the effects of the surfactants on photo-fading of the aminoanthraquinone disperse dyes, the aqueous solutions of 1, 4-diaminoanthraquinone containing anionic surfactants, nonionic surfactants and polyoxyethylene glycol were exposed to light of the 400-watt high-pressure mercury-vapour lamp (Toshiba H 400 P) and rates of photo-fading of the dye were examined. The experimental results suggested the following:(1) The photo-fading reaction of 1, 4-diaminoanthraquinone in the aqueous solutions is of the first order in the initial stage.(2) Among the samples used in present work, sodium dodecyl sulfate, polyoxyethylene glycol and polyoxyethylene dodecylether accelerate the photo-fading reaction of the dye, while the other four retards the reaction more effectively in the order of sodium dodecylbenzene sulfonate < polyoxyethylene nonylphenylether < sodium butylnaphthalene sulfonate < sodium β-naphthalene sulfonate-formaldehyde condensate. This retardation effect may be attributed to the aromatic ring in these molecules and the naphthalene ring is more effective than benzene ring.(3) The surfactants having aromatic ring exhibit twofold retardation effects on photo-fading reacttion of the dye i.e., the roles as the filter and as the inactivating agent for the activated dye by interacting with the dye.(4) The retardation effect of sodium β-naphthalene sulfonate-formaldehyde condensate, especially exerted by interacting with the dye, is the largest of all the samples used. This may be due to the polymeric feature of the condensate.

セロハン膜上の直接ジスアゾ染料の光退色速度

セロハン膜上の直接ジスアゾ染料の光退色速度