Showing papers on "Benzophenone published in 2013"
TL;DR: In this paper, thermolysis of 2 in an attempt to favor a monomeric ketyl radical species unexpectedly led to cleavage of the C-O bond to generate a Zr/Co μ-oxo species featuring an unusual terminal Co−CPh2 carbene linkage.
Abstract: Single electron transfer from the ZrIIICo0 heterobimetallic complex (THF)Zr(MesNPiPr2)3Co–N2 (1) to benzophenone was previously shown to result in the isobenzopinacol product [(Ph2CO)Zr(MesNPiPr2)3Co–N2]2 (2) via coupling of two ketyl radicals. In this work, thermolysis of 2 in an attempt to favor a monomeric ketyl radical species unexpectedly led to cleavage of the C–O bond to generate a Zr/Co μ-oxo species featuring an unusual terminal Co═CPh2 carbene linkage, (η2-MesNPiPr2)Zr(μ-O)(MesNPiPr2)2Co═CPh2 (3). This complex was characterized structurally and spectroscopically, and its electronic structure is discussed in the context of density functional theory calculations. Complex 3 was also shown to be active toward carbene group transfer (cyclopropanation), and silane addition to 3 leads to PhSiH2O–Zr(MesNPiPr2)3Co–N2 (5) via a proposed Co–alkyl bond homolysis route.
89 citations
TL;DR: In this article, benzophenone derivatives in combination with an iodonium salt (and optionally N-vinylcarbazole) or amines have been used as photoinitiating systems.
Abstract: Newly developed benzophenone derivatives in combination with an iodonium salt (and optionally N-vinylcarbazole) or amines have been used as photoinitiating systems. Their abilities to initiate cationic photopolymerization of epoxides and/or radical photopolymerization of acrylates under very soft visible halogen lamp, LED and laser diodes irradiations have been investigated. One of them (BPD5) is particularly efficient for the cationic and radical photopolymerization of an epoxide/acrylate blend in a one-step hybrid cure and leads to the formation of an interpenetrated polymer network IPN upon the house hold blue LED bulb exposure (1 min for getting tack free coatings). The performances attained with some derivatives are better than those obtained with camphorquinone, used as reference photoinitiator, highlighting their high initiating abilities. These systems can be useful to overcome the oxygen inhibition for very low light intensity. The photochemical mechanisms are studied by molecular orbital calcula...
77 citations
TL;DR: This is the first study of the detailed biodegradation pathway of MG by Micrococcus sp.
73 citations
TL;DR: The tris(phosphinoamide)-linked heterobimetallic Co/Zr complex (THF)Zr(MesNPiPr2)3CoN2 (1) has been investigated as a catalyst for the hydrosilylation of ketones with PhSiH3 as discussed by the authors.
71 citations
TL;DR: In this article, a cross-dehydrogenative coupling between anilides and aromatic aldehydes was achieved under aqueous conditions, and a wide variety of the desired benzophenone derivatives was isolated in good to excellent yield.
Abstract: Palladium-catalyzed cross-dehydrogenative coupling between anilides and aromatic aldehydes was achieved under aqueous conditions. A wide variety of the desired benzophenone derivatives was isolated in good to excellent yield. The reaction rate acceleration effect of acid and detergent
has been demonstrated. Mechanistic insight has been obtained from quantum chemical calculations.
71 citations
TL;DR: Aqueous solutions of 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BPTCD) were successfully employed in treatment of cotton fabrics to bring multiple functions onto the cotton cellulose to investigate the overall reaction mechanism of the chemical finishing process.
55 citations
TL;DR: A photo-cross-linkable poly(acrylic acid) (PAA) polymer functionalized with a photoreactive benzophenone group was synthesized and examined as a binder for Si-based anodes.
Abstract: A new photo-cross-linkable poly(acrylic acid) (PAA) polymer functionalized with a photoreactive benzophenone group (PAA-BP) was synthesized and examined as a binder for Si-based anodes. Upon UV irradiation, the PAA-BP binders formed an irreversible cross-linked structure through the formation of a new three-dimensional C–C bond network between the benzophenone moiety and the PAA backbone. The photo-cross-linked PAA-BP binder demonstrated a marginal volume expansion (38%) after full lithiation, compared to conventional binders and this resulted in an improved cycle performance of the Si anode over 100 cycles with a high reversible capacity of ca. 1600 mA h g−1. We attributed this phenomenon to the enhanced mechanical properties of the photo-cross-linked PAA-BP binder, which were evaluated using nanoindentation and swelling measurements.
54 citations
TL;DR: The transformation of two benzophenone UV filters was examined over the pH range 6-11 in the presence of excess aqueous chlorine, and intrinsic rate coefficients from the k(int) were developed as a function of pH for both UV filters.
51 citations
TL;DR: Implementing light-responsive spiropyran functions in polymer films linked to solid surfaces could allow for switching of the chemical and optical surface properties in a fast and spatially controlled fashion.
Abstract: Surface-attached polymer networks that carry light-responsive nitrospiropyran groups in a hydrophilic PDMAA matrix were prepared on planar silicon and glass surfaces and were characterized with respect to their switching behavior under the influence of an external light trigger. Functional polymers bearing light-responsive units as well as photo-cross-linkable benzophenone groups were first synthesized using free radical copolymerization. The number of spiropyran groups in the copolymer was controlled by adjusting the concentration of the respective monomer in the copolymerization feed. The polymer films were prepared by spin-coating the functional polymers from solution and by ultraviolet light (UV)-induced cross-linking utilizing benzophenone photochemistry. On substrates with immobilized benzophenone groups, the complete polymer network is linked to the surface. The dry thickness of the films can be controlled over a wide range from a few nanometers up to more than 1 μm. The integration of such light-switchable organic moieties into a surface-attached polymer network allows one to increase the overall number of light-responsive groups per surface area by adjusting the amount of surface-attached polymer networks. The spiropyran’s function in dry (solvent-free) and swollen polymer films can be reversibly switched by UV and visible irradiation. In addition, the switching in water is faster than in the dry state. Therefore, implementing light-responsive spiropyran functions in polymer films linked to solid surfaces could allow for switching of the chemical and optical surface properties in a fast and spatially controlled fashion.
50 citations
TL;DR: The products obtained from benzophenone adsolubilization presented good adsorption in the full UV region, from UVC to UVA, and good stability to UV radiation, which makes them good candidates for the development of a new generation of sunscreens.
48 citations
TL;DR: The UV-filter BP-4 (2-hydroxy-4-methoxybenzophenone-5-sulfonic acid) has been frequently observed in the environment, showing high potentials to invade drinking water, swimming water, or wastewater reclamation treatment systems, and its possible transformation routes have been investigated.
TL;DR: Malachite green in both the anode and cathode tanks exhibited similar catalytic degradation pathways, and was degraded into oxalic acid as a small molecular organic acid, which was degraded by processes such as demethylation, deamination, nitration, substitution, addition, and other reactions.
TL;DR: In this paper, a benzophenone-based Schiff base was used as a fluorescence chemosensor for the selective detection of Al3+ in one step, and the probe was synthesized in a single step and found to be non-fluorescent due to a combination of photoinduced electron transfer (PET), excited state intramolecular proton transfer (ESIPT) and E/Z isomerism.
Abstract: A benzophenone-based Schiff base 1 has been utilized as a fluorescence chemosensor for the selective detection of Al3+. The probe was synthesized in one step, and found to be non-fluorescent due to a combination of photoinduced electron transfer (PET), excited state intramolecular proton transfer (ESIPT) and E/Z isomerism. Upon addition of Al3+ to a methanolic solution of 1, the development of a strong fluorescence signal was observed with an attractive glowing green emission. This was due to the inhibition of PET, ESIPT and E/Z isomerism, and the activation of chelation enhanced fluorescence (CHEF). The quantum yield of 1–Al3+ was found to be 0.17. The selectivity was tested with 24 different metal and non-metal ions, and established using various spectroscopic tools. The strong affinity of compound 1 for Al3+ was also proven by 1H NMR and mass spectroscopy.
TL;DR: In this paper, the existence of two stable and competitive interaction modes between an alternating poly(dA-dT) decamer and benzophenone, a minor groove adduct and a double insertion structure in which the central base pair is ejected, with hydrogen bonding with proximal groups, locking the DNA-drug complex.
Abstract: From explicit solvent molecular dynamics simulations, we probe the existence of two stable and competitive interaction modes between an alternating poly(dA-dT) decamer and benzophenone, a minor groove adduct and a double insertion structure in which the central base pair is ejected, with hydrogen bonding with proximal groups, locking the DNA–drug complex. The extensive analysis of noncovalent interactions provides a rationale for the existence of this mode, never reported yet between DNA and any organic photosensitizer. We evidence a highly characteristic signature in our simulated circular dichroism spectra that may provide useful guidance for the future experimental efforts, as well as for theoretical investigations aiming at elucidating the energy-transfer mechanism between benzophenone and thymines.
TL;DR: A benzodioxole derivative, 4-(2-(benzodioxol-5-yloxy)ethoxy)benzophenone (BPC2BDO), based on 4-hydroxy benzophenone and sesamol was synthesized, and used as a one-component Type II photoinitiator.
Abstract: A benzodioxole derivative, 4-(2-(benzodioxol-5-yloxy)ethoxy)benzophenone (BPC2BDO), based on 4-hydroxybenzophenone and sesamol was synthesized, and used as a one-component Type II photoinitiator. The structure of BPC2BDO was characterized by elementary analysis, APCI-MS, (1)H NMR, and (13)C NMR. The rate of decomposition (R(d)) of BPC2BDO in acetonitrile was studied by UV-Vis spectroscopy and found that R(d) was proportional to light intensity. Real-time near-IR was used to study the kinetics of photopolymerization of the photoinitiator. As the benzophenone (BP) moiety and hydrogen donor were introduced into one molecule in BPC2BDO, radicals could be generated through intra-molecular reaction due to the close vicinity of the hydrogen donor and BP, which might be faster than inter-molecular reaction. The results also showed that the rate of polymerization of acrylates was significantly higher than that of methacrylates at the same polymerization conditions; the functionality of acrylates, concentration of BPC2BDO, and light intensity affected the polymerization rate and the final conversion.
TL;DR: In this article, the degradation mechanisms of tetraphenyl butadiene (TPB) coatings of the type used in neutrino and dark matter liquid argon experiments were investigated.
Abstract: We report on studies of degradation mechanisms of tetraphenyl butadiene (TPB) coatings of the type used in neutrino and dark matter liquid argon experiments. Using gas chromatography coupled to mass spectrometry we have detected the ultraviolet-blocking impurity benzophenone. We monitored the drop in performance and increase of benzophenone concentration in TPB plates with exposure to ultraviolet (UV) light, and demonstrate the correlation between these two variables. Based on the presence and initially exponential increase in the concentration of benzophenone observed, we propose that TPB degradation is a free radical-mediated photooxidation reaction, which is subsequently confirmed by displaying delayed degradation using a free radical inhibitor. Finally we show that the performance of wavelength-shifting coatings of the type envisioned for the LBNE experiment can be improved by 10-20%, with significantly delayed UV degradation, by using a 20% admixture of 4-tert-Butylcatechol.
TL;DR: With the exception of triphenyl phosphate, detected in one foodstuff, all the packaging material contained the substance(s) found in the food.
Abstract: Three hundred and fifty foodstuffs packaged in printed paper/board were purchased from UK retail outlets. Solvent extracts of all foods and associated quality assurance samples were analysed by gas chromatography-mass spectrometry (GC-MS) to determine the presence and concentrations of 20 printing ink compounds: benzophenone, 4-methylbenzophenone, 2-methylbenzophenone, 3-methylbenzophenone, 4-hydroxybenzophenone, 2-hydroxybenzophenone, 4-phenylbenzophenone, methyl-2-benzoylbenzoate, 1-hydroxycyclohexyl phenyl ketone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethyl-9H-thioxanthen-9-one, 2,2-dimethoxy-2-phenylacetophenone, 2-methyl-4'-(methylthio)-2-morpholinopropiophenone, 4-(4-methylphenylthio)benzophenone, ethyl-4-dimethylaminobenzoate, 2-ethylhexyl-4-(dimethylamino)benzoate, N-ethyl-p-toluene-sulphonamide, triphenyl phosphate and di-(2-ethylhexyl) fumarate. The presence of one or more of the compounds benzophenone, 4-phenylbenzophenone, methyl-2-benzoylbenzoate, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, 4-(4-methylphenylthio)benzophenone, ethyl-4-dimethylaminobenzoate, 2-ethylhexyl-4-dimethylaminobenzoate and triphenyl phosphate was confirmed in some food samples. Analysis of the associated packaging material was also carried out to confirm whether or not it was likely that the occurrence of these compounds in the foods was due to migration from the printed paper/board packaging. With the exception of triphenyl phosphate, detected in one foodstuff, all the packaging material contained the substance(s) found in the food.
TL;DR: In this article, the reaction of 2 with gaseous H2 in toluene solution at room temperature is described, by which the corresponding H2 addition product 4 was formed.
01 Jan 2013
TL;DR: 2 dimensional and 3 dimenional quantitative structure-activity relationships indicated that hydrogen-bond interactions and electrostatic effects were determinants for the genotoxicity of the BPs.
Abstract: Benzophenones (BPs) are widely used in UV filters, fragrance enhancers, and plastic additives. In this study, the genotoxicity of 14 BPs was tested using the SOS/umu assay, and the related substituent contribution was disclosed. The results of this study revealed that the major contributor to the genotoxicity of the BPs was the ortho,para-di-substitution, and the increasing hydroxy substitution on the benzene ring. In addition, the higher the dispersion of the substituent species on the two benzene rings, the lower the genotoxicity exhibited by the compound. Furthermore, 2 dimensional and 3 dimenional quantitative structure-activity relationships (2D- and 3D-QSAR) studies indicated that hydrogen-bond interactions and electrostatic effects were determinants for the genotoxicity of the BPs. The current results provide useful information for the assessment of the potential ecological risk and health effects of BP-type UV filters.
TL;DR: In this paper, the authors compared the efficacy of monofunctional benzophenone and bifunctional bis-benzophenone photoinitiators for inducing radical chain branching reactions in glassy polystyrene (PS) and rubbery poly(n-butyl acrylate) (PnBA).
Abstract: The general mechanism for photo-cross-linking of preformed polymers is studied by comparing the efficacy of monofunctional benzophenone (BP) and bifunctional bis-benzophenone (BP-BP) photoinitiators for inducing radical chain branching reactions in glassy polystyrene (PS) and rubbery poly(n-butyl acrylate) (PnBA). Upon UV irradiation, macroradicals form and initiate a variety of cross-linking and scission reactions. The kinetics and mechanisms of these macroradical reactions were monitored by gel permeation chromatography (GPC) measurements of changes in the polymer molecular weight distributions. Molecular weight increases are associated with chain branching while decreases in molecular weight are indicative of chain scission. We study the early stages of radical recombination where branching is manifest as the formation of three- and four-arm star polymers that are soluble and can be detected/differentiated by GPC. Branching is observed even in glassy PS; however, the reactions are much faster in rubber...
TL;DR: The experimental results as well as DFT quantum chemical calculations clearly indicate that these benzophenone derivatives all react as n-π* excited ketones, and the rate aswell as the activation energy of the reduction steps change parallel with the reaction enthalpies, the determining factor being the stability of the forming aromatic ketyl radicals.
Abstract: The kinetics of the photoreduction of four benzophenone derivatives by isopropyl alcohol was examined in acetonitrile, namely, tetra-meta-trifluoromethyl-, di-para-trifluoromethyl-, di-para-methoxy benzophenone, and, for comparison, the unsubstituted molecule itself. The basic spectroscopic (absorption and phosphorescence spectra) and photophysical (quantum yields and excited state energies) properties were established, and the key kinetic parameters were determined by the laser flash photolysis transient absorption technique. The rate coefficients of both the primary and secondary photoreduction reaction show remarkable dependence on ring substitution. This substantial effect is caused by the considerable change in the activation energy of the corresponding process. The experimental results as well as DFT quantum chemical calculations clearly indicate that these benzophenone derivatives all react as n–π* excited ketones, and the rate as well as the activation energy of the reduction steps change parallel...
TL;DR: It was shown that minor changes in molecular structure can result in highly different phototoxic characteristics.
Abstract: Benzophenone is a phototoxic compound with absorption maxima in the ultraviolet A (UVA) and ultraviolet B (UVB) range. Many benzophenone derivatives are known to be photosensitizing. On the other hand, 2-hydroxy-4-methoxybenzophenone is used as a photoprotective agent. The aim of the present study was to analyse a range of benzophenone derivatives and thus examine the effects of molecular changes in the benzophenone molecule on phototoxic behaviour. Phototoxicity was tested by an in vitro photohaemolysis test. The tested compounds were benzophenone itself and the derivatives 2-hydroxybenzophenone, 2-aminobenzophenone, 2-benzoylbenzoic acid, 3-hydroxybenzophenone, and 4-hydroxybenzo-phenone, as well as the structurally similar compounds 9-fluorenone, 9-fluorenone-2-carboxylic acid, cyclohexyl phenyl ketone, and 1,4-naphtho-quinone. It was shown that minor changes in molecular structure can result in highly different phototoxic characteristics.
TL;DR: The results suggest that the confinement, the formation of a stable radical species, and the singlet oxygen photoproduction are responsible for the selective oxidation processes of benzophenone.
Abstract: This manuscript investigates how incorporation of benzophenone, a well-known triplet sensitizer, within a bis-urea macrocycle, which self-assembles into a columnar host, influences its photophysical properties and affects the reactivity of bound guest molecules. We further report the generation of a remarkably stable organic radical. As expected, UV irradiation of the host suspended in oxygenated solvents efficiently generates singlet oxygen similar to the parent benzophenone. In addition, this host can bind guests such as 2-methyl-2-butene and cumene to form stable solid host–guest complexes. Subsequent UV irradiation of these complexes facilitated the selective oxidation of 2-methyl-2-butene into the allylic alcohol, 3-methyl-2-buten-1-ol, at 90% selectivity as well as the selective reaction of cumene to the tertiary alcohol, α,α′-dimethyl benzyl alcohol, at 63% selectivity. However, these products usually arise through radical pathways and are not observed in the presence of benzophenone in solution. I...
TL;DR: The synthesis of α-imino aldehydes has been achieved through the thermal [1,3]-rearrangement of O-alkenyl benzophenone oximes through a copper-mediated C-O bond coupling between benzophen one oxime and alkenyl boronic acids.
TL;DR: In this article, a dioxomolybdenum(VI) complex has been covalently anchored onto mesoporous titania by a silicon-assisted transesterification route.
Abstract: A dioxomolybdenum(VI) complex has been covalently anchored onto mesoporous titania by a silicon-assisted transesterification route. The grafting of the complex to the mesoporous structure was confirmed by diffuse reflectance infrared Fourier transform, Raman and UV–Vis spectroscopy and by nitrogen sorption experiments. The ability of the grafted complex to activate molecular oxygen (O2) has been evaluated in the photooxidation of diphenylmethane to produce benzophenone. The photooxidation of diphenylmethane was monitored continuously by in situ dispersive Raman spectroscopy. A scheme for the activation of molecular oxygen under very mild conditions is proposed. A comparison with the same complex anchored onto commercial titanium P-25 and silica gel revealed both the beneficial effect of the mesoporous structure and the existence of a synergistic effect between MoO/TiO2/O2/light entities, which promotes the photooxidation process under green chemistry conditions. Finally, the heterogeneous catalyst is sustainable; it can be recycled and reused without significant loss in activity or selectivity.
TL;DR: Undercover agent: Masquerading as a simple donor-acceptor complex, sodium amide substoichiometrically activates tBuZn for the challenging 1,6-addition of a tert-butyl group to benzophenone.
Abstract: Undercover agent: Masquerading as a simple donor-acceptor complex (1), sodium amide substoichiometrically activates tBuZn for the challenging 1,6-addition of a tert-butyl group to benzophenone. In contrast, the nonactivated tBuZn is ineffectual.
TL;DR: In this article, aqueous solutions of poly(ethylene oxide) (PEO) were photocrosslinked by ultraviolet radiation in the presence of benzophenone (BP), indicating the formation of a complex between the reactants.
Abstract: The development of a water-based polymer system that could be photocrosslinked during the drilling of fragile formations could be of a great interest. In this context, aqueous solutions of poly(ethylene oxide) (PEO) were photocrosslinked by ultraviolet radiation in the presence of benzophenone (BP). The photochemical crosslinking reaction showed a rate constant of 1 × 1012 L mol−1 s−1, indicating the formation of a complex between the reactants. The crosslinked PEO was fully characterized showing an yield dependency on the irradiation time, concentration of benzophenone, and on the presence of oxygen. During the study of the effect of BP concentration, it was observed that low concentrations and the presence of oxygen favor chain scission, while crosslinking was the dominant effect at higher BP concentrations. The storage modulus (G′) value for some of the materials was found to be higher than the loss module (G″) suggesting a predominantly elastic solid-like behavior which was corroborated by the scanning electron microscopy (SEM) results. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2458–2467, 2013
Journal Article•
TL;DR: In this article, the photodegradation of polystyrene films has been investigated in the presence of sensitizers such as benzophenone (BP) and thioxanthone (TX).
Abstract: The photodegradation of polystyrene films has been investigated in the presence of sensitizers such as benzophenone (BP) and thioxanthone (TX). The phototransformations were studied by infrared and UV-Vis spectroscopy. The results indicate that these photosensitizers accelerate and increase the efficiency of the photodegradation and the photo-oxidation processes in polystyrene and increase the formation of double bonds in the polymer. In all these process, TX showed a larger photosensitization efficiency than BP. Flash photolysis experiments indicate that the triplet reactivity of both sensitizers towards polystyrene are similar, so that the higher efficiency of thioxanthone when compared with benzophenone should be assigned to its larger absorptivity, as well as to the absorptivity of its degradation products in the irradiating region.
TL;DR: In this paper, a reaction of 3,3',4,4'4'tetrakis(methoxycarbonyl)benzophenone tosylhydrazone with fullerene C60 was used to obtain a novel methano-[60]fullerene derivative bearing four carboxylic groups, whose sodium and potassium salts are water-soluble.
TL;DR: In this paper, steadystate 1H CIDNP, steady-state and laser-flash photolysis in combination with quantum mechanical calculations were applied to study Type I hydrogen abstraction (HA) in three model systems.
Abstract: Cholesterol is one of the most important building blocks of cell membranes. It is also one of the main targets for oxidation via Type I hydrogen abstraction (HA), which leads to a variety of physiological consequences in the human body. To provide a deeper understanding of the oxidation mechanism, steady-state 1H CIDNP, steady-state and laser-flash photolysis in combination with quantum mechanical calculations were applied to study HA in three model systems. The experiments involved photoinduced reactions in a cholesterol–benzophenone mixture and two derivatives, in which aminocholestene and benzophenone are covalently coupled yielding a dyad. It has been found, that a specific orientation of the benzophenone moiety toward the allylic hydrogens of cholesterol/aminocholestene is crucial for the efficient HA. Such a confined topology may play an important role for the particular oxidation of cholesterol in cell membranes.