Ion valence-gated photochromism of an aza-crowned diarylethene.

A non-photochromic diarylethene 2o with an N-phenylaza-15-crown-5 was synthesized. When the nitrogen atom in the aza-crown ring was protonated, it became photochromic due to the prevention of a twisted intramolecular charge transfer (TICT). Although addition of a monovalent metal cation (Li, Na, K, Rb, Cs, Cu, Ag) in acetonitrile could not stop the TICT so that it was not photochromic, the addition of a multivalent metal cation (Mg, Ca, Sr, Ba, Fe, Ni, Al, Sb) changed 2o to be photochromic due to the strong attraction of the lone pair on the nitrogen atom.

Photoexcited triplet state and singlet oxygen generation of quinine, an antimalarial drug.

Energy transfer from the lowest excited triplet (T) state of quinine (QN) to ground-state molecular oxygen produces singlet oxygen. In aqueous solutions, a neutral form QN, a singly protonated cation QNH and doubly protonated cation QNH are present according to their pK values. To the best of our knowledge, the pH dependence of QN-photosensitized singlet oxygen generation has not been reported.

Suppression of menthyl anthranilate (UV-A sunscreen)-sensitized singlet oxygen generation by Trolox and α-tocopherol.

Menthyl anthranilate (MA, tradename meradimate) is a UV-A absorber. The interactions of ground-state molecular oxygen with the long-lived triplet state of MA produce singlet oxygen through energy transfer. The quantum yield of singlet oxygen generation is 0.

A novel characteristic of salicylate UV absorbers: suppression of diethylhexyl 2,6-naphthalate (Corapan TQ)-photosensitized singlet oxygen generation.

2-Ethylhexyl salicylate (EHS, octyl salicylate) and homomenthyl salicylate (HMS, homosalate) are UV-B absorbers used in cosmetic sunscreens. Diethylhexyl 2,6-naphthalate (DEHN, tradename Corapan TQ) used as a mildly effective photostabilizer for labile butylmethoxydibenzoylmethane, the most widely used UV-A absorber, is an efficient singlet oxygen photosensitizer with a high quantum yield of singlet oxygen generation ΦΔ = 0.44 in ethanol.

Suppression of riboflavin-sensitized singlet oxygen generation by l-ascorbic acid, 3-O-ethyl-l-ascorbic acid and Trolox.

Riboflavin (RF), a water-soluble vitamin B, is an endogenous singlet oxygen photosensitizer in human skin and eye. Time profiles of the near-infrared phosphorescence of singlet oxygen generated by RF have been measured in the absence and presence of l-ascorbic acid (AA, vitamin C), 3-O-ethyl-l-ascorbic acid (3-EtAA) and Trolox (TX, a water-soluble analogue of vitamin E) in phosphate buffer (pH 6.8).

Photophysical properties of diethylhexyl 2,6-naphthalate (Corapan TQ), a photostabilizer for sunscreens.

Diethylhexyl 2,6-naphthalate (DEHN, tradename Corapan TQ) is used as a photostabilizer for a widely-used UV-A absorber, butylmethoxydibenzoylmethane (BMDBM). The photophysical properties of DEHN have been studied through measurements of the transient absorption, fluorescence, phosphorescence and EPR spectra in ethanol. The energy level of the lowest excited singlet state of DEHN is higher than that of BMDBM (enol form).

Chitin digestibility is dependent on feeding behaviors, which determine acidic chitinase mRNA levels in mammalian and poultry stomachs.

Chitin, a polymer of N-acetyl-D-glucosamine (GlcNAc), functions as a major structural component in chitin-containing organism including crustaceans, insects and fungi. Recently, we reported that acidic chitinase (Chia) is highly expressed in mouse, chicken and pig stomach tissues and that it can digest chitin in the respective gastrointestinal tracts (GIT). In this study, we focus on major livestock and domestic animals and show that the levels of Chia mRNA in their stomach tissues are governed by the feeding behavior.

Photophysical properties of hexyl diethylaminohydroxybenzoylbenzoate (Uvinul A Plus), a UV-A absorber.

Hexyl diethylaminohydroxybenzoylbenzoate (DHHB, Uvinul A Plus) is a photostable UV-A absorber. The photophysical properties of DHHB have been studied by obtaining the transient absorption, total emission, phosphorescence and electron paramagnetic resonance spectra. DHHB exhibits an intense phosphorescence in a hydrogen-bonding solvent (e.

[Use of a New Video-laryngoscope (McGRATH® X-blade™) in Patients with Difficult Airways].

We describe the use of a new video-laryngoscope (McGRATH® X-blade™, X-blade) in patients with difficult airways. We report four cases of difficult and failed tracheal intubation using a conventional Machintosh laryngoscope and McGRATH® MAC in which tracheal intubation was accomplished swiftly and easily using a newly designed videolaryngoscope, the X-blade. The whole glottis was easily visible (Cormack-Lehane grade 1) with the X-blade.

Optical and electron paramagnetic resonance studies of the excited triplet states of UV-B absorbers: 2-ethylhexyl salicylate and homomenthyl salicylate.

The energy levels and lifetimes of the lowest excited triplet (T1) states of UV-B absorbers, 2-ethylhexyl salicylate (EHS) and homomenthyl salicylate (HMS), and their deprotonated anions (EHS(-) and HMS(-)) were determined through measurements of phosphorescence and electron paramagnetic resonance (EPR) spectra in rigid solutions at 77 K. The observed T1 energies of EHS and HMS are higher than those of butylmethoxydibenzoylmethane, the most widely used UV-A absorber, and octyl methoxycinnamate, the most widely used UV-B absorber. The T1 states of EHS, HMS, EHS(-) and HMS(-) were assigned to almost pure (3)ππ* state from the observed T1 lifetimes and zero-field splitting parameters.

Photoexcited triplet states of UV-B absorbers: ethylhexyl triazone and diethylhexylbutamido triazone.

The excited states of UV-B absorbers, ethylhexyl triazone (EHT) and diethylhexylbutamido triazone (DBT), have been studied through measurements of UV absorption, fluorescence, phosphorescence, triplet-triplet absorption and electron paramagnetic resonance spectra in ethanol. The energy levels of the lowest excited singlet (S1) and triplet (T1) states and quantum yields of fluorescence and phosphorescence of EHT and DBT were determined. In ethanol at 77 K, the deactivation process of EHT and DBT is predominantly fluorescence, however, a significant portion of the S1 molecules undergoes intersystem crossing to the T1 state.

Pyogenic granuloma of the ileum diagnosed by double-balloon enteroscopy.

A pyogenic granuloma (PG) is a capillary hemangioma that usually occurs on the skin or in the oral cavity; it is rarely observed in the gastrointestinal tract. We herein describe a case of a 86-year-old woman who presented with anemia. Esophagogastroduodenoscopy and colonoscopy did not reveal any significant bleeding focus, but capsule endoscopy revealed a bleeding focus in the small intestine.

Photoexcited states of UV absorbers, benzophenone derivatives.

The UV absorption, phosphorescence and phosphorescence-excitation spectra of benzophenone (BP) derivatives used as organic UV absorbers have been observed in rigid solutions at 77 K. The triplet-triplet absorption spectra have been observed in acetonitrile at room temperature. The BP derivatives studied are 2,2',4,4'-tetrahydroxybenzophenone (BP-2), 2-hydroxy-4-methoxybenzophenone (BP-3), 2,2'-dihydroxy-4,4'-dimethoxybenzophenone (BP-6), 5-chloro-2-hydroxybenzophenone (BP-7) and 2-hydroxy-4-n-octyloxybenzophenone (BP-12).

Triplet-triplet energy transfer from a UV-A absorber butylmethoxydibenzoylmethane to UV-B absorbers.

The phosphorescence decay of a UV-A absorber, 4-tert-butyl-4'-methoxydibenzolymethane (BMDBM) has been observed following a 355 nm laser excitation in the absence and presence of UV-B absorbers, 2-ethylhexyl 4-methoxycinnamate (octyl methoxycinnamate, OMC) and octocrylene (OCR) in ethanol at 77 K. The lifetime of the lowest excited triplet (T1) state of BMDBM is significantly reduced in the presence of OMC and OCR. The observed quenching of BMDBM triplet by OMC and OCR suggests that the intermolecular triplet-triplet energy transfer occurs from BMDBM to OMC and OCR.

Optical and time-resolved electron paramagnetic resonance studies of the excited states of a UV-B absorber (4-methylbenzylidene)camphor.

The excited states of UV-B absorber (4-methylbenzylidene)camphor (MBC) have been studied through measurements of UV absorption, phosphorescence, triplet-triplet (T-T) absorption, and steady-state and time-resolved electron paramagnetic resonance spectra in ethanol. The energy level and lifetime of the lowest excited triplet (T(1)) state of MBC were determined. The energy level of the T(1) state of MBC is much lower than that of photolabile 4-tert-butyl-4'-methoxydibenzoylmethane.

Photoexcited singlet and triplet states of a UV absorber ethylhexyl methoxycrylene.

The excited states of UV absorber, ethylhexyl methoxycrylene (EHMCR) have been studied through measurements of UV absorption, fluorescence, phosphorescence and electron paramagnetic resonance (EPR) spectra in ethanol. The energy levels of the lowest excited singlet (S1) and triplet (T1) states of EHMCR were determined. The energy levels of the S1 and T1 states of EHMCR are much lower than those of photolabile 4-tert-butyl-4'-methoxydibenzoylmethane.

Excited states of menthyl anthranilate: a UV-A absorber.

The photophysical properties of menthyl anthranilate (MA), a UV-A absorber, have been studied through measurements of UV absorption, fluorescence, triplet-triplet absorption and time-resolved thermal lens in ethanol at room temperature and/or 77 K. The phosphorescence and time-resolved electron paramagnetic resonance spectra have also been observed in ethanol at 77 K. The energy levels of the lowest excited singlet (S(1)) state and triplet (T(1)) state were determined.

Photophysical properties of dioctyl 4-methoxybenzylidenemalonate: UV-B absorber.

Dioctyl 4-methoxybenzylidenemalonate (DOMBM) is an effective stabilizer for photolabile 4-tert-butyl-4'-methoxydibenzoylmethane (BMDBM). DOMBM is superior to the most widely used UV-B absorber, octyl methoxycinnamate (OMC), at preserving its UV-B absorbance in the presence of BMDBM. The energy levels of the lowest excited singlet (S(1)) and triplet (T(1)) states of DOMBM were determined by measuring fluorescence and phosphorescence spectra in ethanol at 77 K.

Photoexcited triplet states of new UV absorbers, cinnamic acid 2-methylphenyl esters.

Phosphorescence spectra of nonphosphorescent or very weakly phosphorescent new UV absorbers, 2-methylphenyl cinnamate (MePC), 2-methylphenyl 4-methoxycinnamate (MePMC) and 2-methylphenyl 4-ethoxycinnamate (MePEC) have been observed by using external heavy atom effects of ethyl iodide in ethanol at 77 K. The lowest excited triplet (T(1)) energies of these new UV absorbers are lower than those of a widely used UV-A absorber, 4-tert-butyl-4'-methoxydibenzoylmethane (BM-DBM), in both keto and enol forms. The intermolecular triplet-triplet energy transfer from photolabile BM-DBM to MePMC was observed by measuring the time-resolved phosphorescence spectra.

Photoinduced diffusive mass transfer in o-Cl-HABI amorphous thin films.

The first demonstration of photoinduced surface relief grating formation using amorphous thin films composed of a radical dissociative photochromic compound, 2,2'-di(ortho-chlorophenyl)-4,4',5,5'-tetraphenylbiimidazole, show that mass transfer occurred from the UV-light-irradiated area to the shaded area by patterned light irradiation (365 nm).

Optical and electron paramagnetic resonance studies of the excited states of 4-tert-butyl-4'-methoxydibenzoylmethane and 4-tert-butyl-4'-methoxydibenzoylpropane.

The excited states of 4-tert-butyl-4'-methoxydibenzoylmethane (BM-DBM) and 4-tert-butyl-4'-methoxydibenzoylpropane (BM-DBP), the model of the keto form of BM-DBM, have been studied through measurements of UV absorption, fluorescence, phosphorescence, and electron paramagnetic resonance spectra in ethanol at 77 K. The energy levels and lifetimes of the lowest excited triplet (T(1)) states of BM-DBP, dibenzoylpropane (DBP), the model of the keto form of dibenzoylmethane (DBM), and the keto and enol forms of BM-DBM and DBM were determined. The energy level of the T(1) state of the keto form is much higher than that of the enol form in BM-DBM.

Ultrafast photodissociation dynamics of a hexaarylbiimidazole derivative with pyrenyl groups: dispersive reaction from femtosecond to 10 ns time regions.

The photodissociation dynamics of a hexaarylbiimidazole (HABI) derivative with two pyrenyl groups was investigated by time-resolved transient absorption spectroscopy and fluorescence measurements. Transient absorption spectroscopy revealed that photodissociation took place in the wide time region of <100 fs to 10 ns. On the other hand, fluorescence time profiles showed the dynamic red shift in the time region <100 ps.

A new family of pi-conjugated delocalized biradicals: Electronic structures of 1,4-bis(2,5-diphenylimidazol-4-ylidene)cyclohexa-2,5-diene.

A new family of pi-conjugated delocalized biradical compound is developed. The solution of 1,4-bis(2,5-diphenylimidazol-4-ylidene)cyclohexa-2,5-diene shows the ESR signal consisting of a moderately broad unresolved line, Delta H(pp) approximately 1 mT, at room temperature. The presence of the thermal equilibrium between a triplet biradical state and a singlet state is confirmed by the ESR measurements, and the spin concentration is determined as 7.

Synthesis and photochemical properties of a photochromic iron(II) complex of hexaarylbiimidazole.

The photochromic ligand bis(terpyridyl)hexaarylbiimidazole (bistpy-HABI) and the Fe(II) complex of bistpy-HABI with formula [{Fe(tpy)}2.bistpy-HABI](PF6)4.4H2O were synthesized and characterized.