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Showing papers on "Benzophenone published in 2010"


Journal ArticleDOI
TL;DR: In this paper, the authors reported efficient phosphorescence from the crystals of benzophenone and its derivatives with a general formula of (X-C6H4)2C═O (X = F, Cl, Br) as well as methyl 4-bromobenzoate and 4,4′-dibromobiphenyl under ambient conditions.
Abstract: Phosphorescence has rarely been observed in pure organic chromophore systems at room temperature. We herein report efficient phosphorescence from the crystals of benzophenone and its derivatives with a general formula of (X-C6H4)2C═O (X = F, Cl, Br) as well as methyl 4-bromobenzoate and 4,4′-dibromobiphenyl under ambient conditions. These luminogens are all nonemissive when they are dissolved in good solvents, adsorbed on TLC plates, and doped into polymer films, because active intramolecular motions such as rotations and vibrations under these conditions effectively annihilate their triplet excitons via nonradiative relaxation channels. In the crystalline state, the intramolecular motions are restricted by the crystal lattices and intermolecular interactions, particularly C−H···O, N−H···O, C−H···X (X = F, Cl, Br), C−Br···Br−C, and C−H···π hydrogen bonding. The physical constraints and multiple intermolecular interactions collectively lock the conformations of the luminogen molecules. This structural rigi...

656 citations


Journal ArticleDOI
TL;DR: In this paper, the X-ray crystal structure of N-(5,5-dimethyl-2-oxo-2λ 5 -[1,3,2]dioxaphosphinan-2,yl-methyl)-N-methyl-p-toluidine was determined.
Abstract: The dehydrogenative α-phosphonation of substituted N,N-dialkylanilines by dialkyl H-phosphonates was achieved under mild conditions by using environmentally benign iron(II) chloride as catalyst and tert-butyl hydroperoxide as oxidant. The reaction proceeded in the presence of electron-donating (methoxy, methyl, benzyl) and electron-withdrawing ring-substitutents (bromo, carbonyl, carboxyl, m-nitro) in moderate to good yields. The X-ray crystal structure of N-(5,5-dimethyl-2-oxo-2λ 5 -[1,3,2]dioxaphosphinan-2-yl-methyl)-N-methyl-p-toluidine was determined. Bis-(4-(dimethylamino)phenyl)methane and bis-4,4'-(dimethylamino)benzophenone underwent bisphosphonation selectively by respective monophosphonation at the remote dimethyl-amino groups. Furthermore, the use of excess dialkyl H-phosphonate and oxidant allowed us to functionalize both methyl groups of N(CH 3 ) 2 in N,N-dimethyl-p-toluidine and N,N-dimethylaminomesidine, respectively, to obtain α,α'-bisphosphonato-amines in high yield.

111 citations


Journal ArticleDOI
TL;DR: In this article, N-heterocyclic carbene-boryl radicals (NHC-BH2•) derived from readily available N-Heterocyclics carbene−boranes are found to be efficient initiators for acrylate photopolymerization.
Abstract: Newly discovered N-heterocyclic carbene-boryl radicals (NHC-BH2•) derived from readily available N-heterocyclic carbene−boranes are found to be efficient initiators for acrylate photopolymerization. Laser flash photolysis (LFP) experiments were used to generate three carbene-boryl radicals, which were characterized by their transient absorption spectra with the aid of DFT calculations. Rate constants were measured for the generation of the carbene-boryl radicals by hydrogen abstraction with tert-butoxyl radical, a ketophosphonyl radical, and triplet benzophenone. Rate constants were also measured for the reactions of the carbene-boryl radicals with oxygen, three alkenes, two alkyl chlorides, and diphenyliodonium hexafluorophosphate. The observed trends were interpreted with the aid of measured oxidation potentials of the carbene−boranes and calculated ionization potentials of the carbene-boryls. N-Heterocyclic carbene−boranes show excellent potential as both photopolymerization co-initiators and mediators...

106 citations


Journal ArticleDOI
18 Jun 2010-Science
TL;DR: It is shown that the dominant TT mechanism switches from tunneling to wire-like hopping between bridge lengths 1 and 2, and the crossover observed for TT can be determined by direct observation of the bridge-occupied state.
Abstract: Triplet energy transfer (TT), a key process in molecular and organic electronics, generally occurs by either strongly distance-dependent single-step tunneling or weakly distance-dependent multistep hopping. We have synthesized a series of pi-stacked molecules consisting of a benzophenone donor, one to three fluorene bridges, and a naphthalene acceptor, and studied the rate of TT from benzophenone to naphthalene across the fluorene bridge using femtosecond transient absorption spectroscopy. We show that the dominant TT mechanism switches from tunneling to wire-like hopping between bridge lengths 1 and 2. The crossover observed for TT can be determined by direct observation of the bridge-occupied state.

102 citations


Journal ArticleDOI
TL;DR: Under optimal conditions, practically 100% of the initial substrate and COD were eliminated in approximately 35 min of electrolysis; indicating that the early CV by-products were completely degraded by the electrochemical system.

96 citations


Journal ArticleDOI
TL;DR: The behavior of six cyclic acetals and related compounds in the photoinitiation step of a radical photopolymerization was investigated in this article, where the photochemical mechanisms of the production of initiating radicals and explain the differences in reactivity were investigated.
Abstract: The behavior of six cyclic acetals and related compounds in the photoinitiation step of a radical photopolymerization was investigated. As shown by the photopolymerization kinetic data obtained from FTIR spectroscopy, most of them are efficient coinitiators in the presence of benzophenone (BP) with efficiencies close to a reference amine coinitiator (ethyl dimethylaminobenzoate, EDB). Laser flash photolysis and ESR spin trapping technique were used to study the photochemical mechanisms of the production of initiating radicals and explain the differences in reactivity. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

77 citations


Journal ArticleDOI
TL;DR: The reductions of benzophenone and anthracene with dimeric magnesium(I) complexes lead to thermally stable magnesium ketyl and magnesium anthracenes complexes, respectively; both have been structurally characterised.

58 citations


Journal ArticleDOI
TL;DR: Investigations contradicted the published conclusions on the aqueous coordination chemistry of AT(2)12C4, but also confirmed the unique and unexpected selectivity of the macrocycle for Fe(3+) in nonaqueous solvents.
Abstract: The non-siderophoric Fe3+ photocage FerriCast (4,5-dimethoxy-2-nitrophenyl)-[4-(1-oxa-4,10-dithia-7-aza-cyclododec-7-yl)phenyl] methanol (2) has been prepared in high yield using an optimized two-step reaction sequence that utilizes a trimethylsilyl trifluoromethanesulfonate (TMSOTf) assisted electrophilic aromatic substitution as the key synthetic step. Spectrophotometric assessment of Fe3+ binding to FerriCast revealed a binding stoichiometry and metal ion affinity dependent on the nature of the counterion. Exposure of FerriCast to 350 nm light initiates a photoreaction that converts FerriCast into FerriUnc (4,5-dimethoxy-2-nitrosophenyl)-[4-(1-oxa-4,10-dithia-7-aza-cyclododec-7-yl)phenyl]-methanone), which binds Fe3+ less strongly owing to resonance delocalization of the anilino lone pair into the benzophenone π-system. The release of Fe3+ upon photolysis of FerriCast also was evaluated using a previously reported turn-on fluorescent sensor that utilizes the same macrocyclic ligand (4-(1-oxa-4,10-dithi...

51 citations


Journal ArticleDOI
TL;DR: A diversity‐oriented solution‐phase approach featuring alkylation of N‐terminal benzophenone semicarbazone aza‐Gly‐Xaa dipeptides using different alkyl halides in the presence of potassium tert‐butoxide as base may provide useful tools for studying peptide science.
Abstract: Aza-peptides have been used as tools for studying SARs in programs aimed at drug discovery and chemical biology. Protected aza-dipeptides were synthesized by a solution-phase submonomer approach featuring alkylation of N-terminal benzophenone semicarbazone aza-Gly-Xaa dipeptides using different alkyl halides in the presence of potassium tert-butoxide as base. Benzophenone protected aza-dipeptide tert-butyl ester 31c was selectively deprotected at the C-terminal ester or N-terminal hydrazone to afford, respectively, aza-dipeptide acid and amine building blocks 36c and 40c, which were introduced into longer aza-peptides. Alternatively, removal of the benzophenone semicarbazone protection from aza-dipeptide methyl esters 29a-c led to intramolecular cyclization to produce aza-DKPs 39a-c. In light of the importance of aza-peptides and DKPs as therapeutic agents and probes of biological processes, this diversity-oriented solution-phase approach may provide useful tools for studying peptide science.

49 citations


Journal ArticleDOI
TL;DR: In this paper, a main chain polymeric benzophenone photoinitiator (PBP) was synthesized by using Thiol-ene Click Chemistry and characterized with 1H NMR, FTIR, UV, and phosphorescence spectroscopies.
Abstract: Main chain polymeric benzophenone photoinitiator (PBP) was synthesized by using “Thiol-ene Click Chemistry” and characterized with 1H NMR, FTIR, UV, and phosphorescence spectroscopies. PBP as a polymeric photoinitiator presented excellent absorption properties (e294 = 28,300 mol−1L−1cm−1) compared to the molecular initiator BP (e252 = 16,600 mol−1L−1cm−1). The triplet energy of PBP was obtained from the phosphorescence measurement in 2-methyl tetrahydrofurane at 77 K as 298.3 kJ/mol and according to phosphorescence lifetime, the lowest triplet state of PBP has an n-π* nature. Triplet–triplet absorption spectrum of PBP at 550 nm following laser excitation (355 nm) were recorded and triplet lifetime of PBP was found as 250 ns. The photoinitiation efficiency of PBP was determined for the polymerization of Hexanedioldiacrylate (HDDA) with PBP and BP in the presence of a coinitiator namely, N-methyldiethanolamine (MDEA) by Photo-DSC. The initiation efficiency of PBP for polymerization of HDDA is much higher than for the formulation consisting of BP. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

45 citations


Journal ArticleDOI
TL;DR: Star polymers with thermoresponsive arms, synthesized via atom transfer radical polymerization (ATRP), exhibit the low critical solution temperature (LCST) at 27 °C, slightly lower than LCST of either MI or Bzp-MI.

Journal ArticleDOI
TL;DR: The chemistry of three N-heterocyclic carbene (NHC) complexes of GeR2, where R = Cl (1), OtBu (2), Mes (3) (Mes = 2,4,6-trimethylphenyl), toward 2,3-dimethylbutadiene (DMB), 3,5-di-tert-butylorthoquinone, methyl iodide, pivalic acid, and benzophenone is reported as mentioned in this paper.

Journal ArticleDOI
TL;DR: A general two-step synthesis of substituted 3-aminoindazoles from 2-bromobenzonitriles involving a palladium-catalyzed arylation of benzophenone hydrazone followed by an acidic deprotection/cyclization sequence is described.
Abstract: A general two-step synthesis of substituted 3-aminoindazoles from 2-bromobenzonitriles involving a palladium-catalyzed arylation of benzophenone hydrazone followed by an acidic deprotection/cyclization sequence is described. This procedure offers a general and efficient alternative to the typical S(N)Ar reaction of hydrazine with o-fluorobenzonitriles.

Journal ArticleDOI
TL;DR: In this article, the electronic structure of various types of model carbonyl silaylides was investigated using DFT calculations, and the diversity of the reaction modes was explained by invoking the substituent effects on the electronic nature of the initially formed carbonylsides.

Journal ArticleDOI
TL;DR: A series of thiosemicarbazone analogs based on the benzophenone, thiophene, pyridine, and fluorene molecular frameworks has been prepared by chemical synthesis and evaluated as small-molecule inhibitors of the cysteine proteases cathepsin L and cat hepsin B.

Journal ArticleDOI
TL;DR: In this article, the photopolymerization ability of photosensitized alkoxyamines has been investigated, and electron spin resonance and density functional theory allow to support the interactions encountered between the photosensitizer (benzophenone and isopropylthioxanthone) and the alkoxyamine (CO bond breaking and hydrogen transfer).
Abstract: The photopolymerization ability of photosensitized alkoxyamines has been investigated. These compounds behave as interesting two-component photoinitiators. Laser flash photolysis, electron spin resonance, and density functional theory allow to support the interactions encountered between the photosensitizer (benzophenone and isopropylthioxanthone) and the alkoxyamines (CO bond breaking and hydrogen transfer) and the side reactions of the nitroxide radical with photosensitizer (electron transfer). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2910–2915, 2010

Journal ArticleDOI
TL;DR: Two new prenylated benzophenone peroxide derivatives, peroxysampsones A and B, together with a known compound, plukenetione C, were isolated from the roots of the Chinese medicinal plant Hypericum sampsonii, and their structures were elucidated by detailed spectral analysis.
Abstract: Two new prenylated benzophenone peroxide derivatives, peroxysampsones A and B (1 and 2, resp.), together with a known compound, plukenetione C (3), were isolated from the roots of the Chinese medicinal plant Hypericum sampsonii, and their structures were elucidated by detailed spectral analysis. These compounds are the unusual peroxides of polyprenylated benzophenone derivatives, containing the unique caged moiety of 4,5-dioxatetracyclo[9.3.1.1(9,13).0(1,7)]hexadecane-12,14,15-trione. In the biological test, peroxysampsone A (1) showed comparable activity with norfloxacin against a NorA over-expressing multidrug-resistant (MDR) strain of Staphylococcus aureus SA-1199B.

Journal ArticleDOI
TL;DR: In this paper, 4-Chloropyridine can be converted for about 70% into a complex magnesium compound, which reacts in the manner of a Grignard compound with aldehydes or ketones, forming (4-pyridyl)-carbinols.
Abstract: 4-Chloropyridine can be converted for about 70% into a complex magnesium compound, which reacts in the manner of a Grignard compound with aldehydes or ketones, forming (4-pyridyl)-carbinols; with orthoformic ester, (4-pyridyl)-methanal-acetal is formed. The reaction of 4-lithiopyridine with benzophenone and with ethyl benzoate respectively leads to the formation of (4-pyridyl)-diphenyl-carbinol and to bis-(4-pyridyl)-phenyl-carbinol respectively. With aromatic nitriles, (4-pyridyl)-aryl ketones are formed. The reactions of 4-lithiopyridine with cyanopyridines or with pyridine-carboxylic esters lead to the formation of bis-pyridyl ketones, e.g., bis-(4-pyridyl) ketone. Quinolyl ketones are obtained by starting from 3-lithioquinoline.

Journal ArticleDOI
19 Jan 2010-Langmuir
TL;DR: The successful covalent linking of green fluorescence protein and streptavidin to patterned benzophenone-modified boron-doped diamond (BDD) electrodes is demonstrated and the preservation of the biological activity was furthermore underlined by photoimmobilization of peptides directly onto Benzophenone modified BDD using a photomask.
Abstract: The successful covalent linking of green fluorescence protein and streptavidin to patterned benzophenone-modified boron-doped diamond (BDD) electrodes is demonstrated. Photoreactive benzophenone moieties were covalently grafted to oxidized diamond surfaces via an esterification reaction. Patterned BDD surfaces were obtained using a UV/ozone lithographic approach either on hydrogen-terminated BDD or on poly(ethylene)-glycol-modified BDD surfaces. UV light (λ = 365 nm) irradiation of the patterned BDD surfaces in the presence of green fluorescence protein (GFP) or streptavidin resulted in the covalent immobilization of the proteins. The presence of poly(ethylene) glycol chains reduces significantly the nonspecific adsorption of the proteins. The success of the photoimmobilization of streptavidin was evidenced through biomolecular interaction with avidin. The preservation of the biological activity was furthermore underlined by photoimmobilization of peptides directly onto benzophenone modified BDD using a p...

Journal ArticleDOI
TL;DR: In this article, the cleavage of four coumarin dimers, the syn-head-to-tail (ht) dimer of parent coumarins (syn-ht-CC1), the anti-and syn-hh dimers of 6-methylcoumarin (anti-hh-CC2 and syn-HH-CC3), were studied by UV-vis and IR spectroscopy and HPLC upon direct 254nm irradiation as well as sensitized excitation.
Abstract: The cleavage of four coumarin dimers, the syn-head-to-tail (ht) dimer of parent coumarin (syn-ht-CC1), the anti- and syn-hh dimers of 6-methylcoumarin (anti-hh-CC2 and syn-hh-CC2, respectively) and the anti-hh dimer of 6-dodecylcoumarin (anti-hh-CC3), was studied by UV–vis and IR spectroscopy and HPLC upon direct 254 nm irradiation as well as sensitized excitation. The quantum yield of dimer splitting is Φsp = 0.1–0.3 in various solvents and the effects of structure and solvent polarity are small. In certain solvents some of the dimers produced CO2 along with the monomers in the splitting reaction. Electron transfer from dimers to the triplet state of sensitizers, such as benzophenone or 9,10-anthraquinone, was observed in acetonitrile.

Journal ArticleDOI
TL;DR: Two colorimetric anion sensors have been synthesized where both a benzophenone group and a nitrophenyl group were used as signalling units and urea/thiourea moieties as binding sites as discussed by the authors.
Abstract: Two new colorimetric anion sensors have been synthesised where both a benzophenone group and a nitrophenyl group were used as signalling units and urea/thiourea moieties as binding sites. The receptors, effectively and selectively, recognised fluoride and carboxylate anions from other anions such as chloride, bromide, iodide, perchlorate, hydrogen sulphate and nitrate in DMSO.

Journal ArticleDOI
TL;DR: In this article, a hybrid photoinitiator for visible light photopolymerization, (η 6 -3-benzoyl-4-chlorodiphenylamine) ( η 5 -cyclopentadienyl) iron hexafluorophosphate (Fc-NBP), was synthesized and studied.

Journal ArticleDOI
TL;DR: The ripe edible fruits of Psidium guajava L. was phytochemically investigated, and new benzophenone glycosides were discovered, and the complete spectroscopic assignments for 3 were reported.

Journal ArticleDOI
TL;DR: In this paper, the efficiency of thiol-functionalized photoinitiators in combination with amine co-initiator was compared to benzophenone and isopropylthioxanthone with co-innitiators, and the cleavage of 2, 2-dimethoxy-1,2-diphenylethan-1-one in acrylic resins.


Journal ArticleDOI
TL;DR: In this article, the triplet state of benzophenone nanocrystals was studied by laser flash photolysis transmission spectroscopy in the presence of several possible quenchers: anionic and cationic surfactants, dissolved oxygen, and as a function of solvent deuteration.

Journal ArticleDOI
TL;DR: In this paper, the experimental results of UV measurements made on an extensive series of unsymmetrically substituted methylbenzophenones in solution (ethanol and iso-octane) were compared with their previously published UV measurements on symmetric substituted benzophenones and correlated with literature data on the UV absorption of acetophenones.
Abstract: This article gives the experimental results of UV measurements made on an extensive series of unsymmetrically substituted methylbenzophenones in solution (ethanol and iso-octane). The results obtained are compared with our previously published UV measurements on symmetrically substituted benzophenones and correlated with literature data on the UV absorption of acetophenones. From this investigation it appears that for the benzophenone series the oscillator strength f is an additive quantity, a fact which is very useful in comparing the various ketones with one another. The comparison with acetophenone - in which not only f, but also the wavelength of the conjugative absorption band plays a part - supplied useful information on the position of the phenyl rings relative to the CO group.

Journal ArticleDOI
TL;DR: Two diamine diamine monomers, Bis-4,4′[(4-aminophenyl-2,2′-isopropylidene phenyloxy)] diphenylsulfone and benzophenone were synthesized in this paper.
Abstract: Two novel aromatic diamine monomers, Bis-4,4′[(4-aminophenyl-2,2′-isopropylidene phenyloxy)] diphenylsulfone and Bis-4,4′[(4-aminophenyl-2,2′-isopropylidene phenyloxy)] benzophenone were synthesize...

Journal ArticleDOI
TL;DR: In this article, a photo-differential scanning calorimetry experiment was conducted on a bimolecular photoinitiators (PIs) for radical polymerization of acrylates.
Abstract: Typical bimolecular photoinitiators (PIs) for radical polymerization of acrylates show only poor photoreactivity because of the unwanted effect of back electron transfer. Therefore, a PI system consisting of benzaldoxime esters and 4-methyl benzophenone was investigated by photo-differential scanning calorimetry experiments. Surprisingly, reactivities are comparable to that of classical monomolecular Type I PIs like Darocur 1173, probably because of an energy transfer from the triplet state of the benzophenone-based sensitizer to the oxime ester initiator. Furthermore, sufficient thermal stability was proven by TGA and storage stability experiments of a resin formulation under elevated temperature. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

Journal ArticleDOI
TL;DR: Intermolecular radical amination reactions of various primary, secondary, and tertiary alkyl radicals by using trimethylstannylated benzophenone imine A as a novel radical acceptor to provide imines of type B are described.