Photoinduced nitric oxide release from a nitrobenzene derivative in mitochondria

We report a novel NO donor (RpNO), containing a 2,6-dimethylnitrobenzene moiety for photocontrollable NO release and a rhodamine moiety for targeting to mitochondria. Photorelease of NO from RpNO in aqueous solution was confirmed by means of ESR analysis. Cellular release of NO from RpNO was confirmed with the aid of DAF-FM DA, an NO-specific fluorescence probe. RpNO was colocalized with MitoTracker Green FM, a mitochondrial stain, in HCT116 colon cancer cells and exhibited photodependent cytotoxicity. Our results indicate that RpNO is an effective NO donor for time-controlled, mitochondria-specific NO treatment.     

Photoinduced in situ generation of a DNA-binding benzothiazoloquinolinium derivative

A styrylbenzothiazole substrate that has no significant affinity towards DNA was transformed photochemically into a DNA-binding benzothiazoloquinolinium ion. The photoreaction may be performed directly in the presence of DNA thus establishing the DNA-ligand interaction in situ with temporal control.     

Photocurrent generation from semiconducting manganese oxide nanosheets in response to visible light

Unilamellar nanosheet crystallites of manganese oxide generated the anodic photocurrent under visible light irradiation (lambda < 500 nm), while the nanosheets themselves were stable as revealed by in-plane XRD and UV-visible absorption spectra. The band gap energy was estimated to be 2.23 eV on the basis of the photocurrent action spectrum. The molecular thickness of approximately 0.5 nm may facilitate the charge separation of excited electrons and holes, which is generally very difficult for strongly localized d-d transitions. The monolayer film of MnO2 nanosheets exhibited the incident photon-to-electron conversion efficiency of 0.16% in response to the monochromatic light irradiation (lambda = 400 nm), which is comparable to those for sensitization of monolayer dyes adsorbed on a flat single-crystal surface. The efficiency declined with increasing the layer number of MnO2 nanosheets, although the optical absorption was enhanced. The recombination of the excited electron-hole pairs may become dominant when the carriers need to migrate a longer distance than 1 layer through multilayered nanosheets.     

8-羟基喹啉衍生物对某些阴离子的双重光谱响应

本文以5-甲酰基-8-羟基喹啉(5M8Q)作为阴离子识别探针,通过紫外、荧光等光谱仪考察其对阴离子识别作用。实验显示:在乙腈溶液中5M8Q对F-、CH3COO-和H2PO4-等阴离子有灵敏的识别作用:F-、CH3COO-和H2PO4-可诱导5M8Q吸收光谱红移,吸收峰位置由322nm红移至400nm。当F-、CH3COO-和H2PO4-浓度为5M8Q两倍当量时,5M8Q荧光显著增强且分别增强至103、60和13倍。结果表明:5M8Q对F-、CH3COO-和H2PO4-有灵敏的双重光谱响应,并且表现出荧光增强型识别性质。     

Second harmonic generation from small gold metallic particles: from the dipolar to the quadrupolar response

Hyper Raleigh scattering, a common technique to investigate the second harmonic light scattered from a liquid suspension of molecular compounds and to determine their quadratic hyperpolarizability, has been used for aqueous suspensions of gold nanoparticles, the diameter of which ranges from 20 up to 150 nm. The hyper Rayleigh signal intensity was recorded as a function of the angle of polarization of the incident fundamental wave. For the particles with a diameter smaller than 50 nm, the response is dominated by the dipolar contribution arising from the deviation of the particle shape from that of a perfect sphere. For larger diameter particles, retardation effects in the interaction of the electromagnetic fields with the particles cannot be neglected any longer and the response deviates from the pure dipolar response, exhibiting a strong quadrupolar contribution. It is then shown that in order to quantify the relative magnitude of these two dipolar and quadrupolar contributions, a weighting parameter zeta(V) which equals unity for a pure quadrupolar contribution and vanishes for a pure dipolar response, can be introduced.     

The hydrogenation of nitrobenzene to aniline: a new mechanism

The Haber mechanism describing the process of hydrogenating nitrobenzene to aniline is shown to be incorrect and a new mechanism is proposed.     

Novel rearrangement reaction of a 6,14-endoethanomorphinan derivative to a benzomorphan derivative

Treatment of 7α-hydroxymethylendoethenomorphinan derivative with trifluoromethanesulfonic anhydride at rt and subsequent toluene reflux afforded a novel lactone by rearrangement reaction. The skeleton of the lactone is analogous to that of the benzomorphan like pentazocine, which is a useful analgesic. The rearrangement reaction opens the door to a facile synthesis from the 4,5-epoxymorphinans to the benzomorphan derivatives. On the basis of careful examination of the reaction intermediates, a reaction mechanism was proposed.     

Synthesis of a cisplatin derivative from lithocholic acid

A new steroidal-platinum(II) hybrid compound was synthesized using a simple and efficient methodology. The synthesis was performed by a convergent approach with cross metathesis (CM) as a key step. An olefin derived from lithocholic acid and a vinyl substituted ethylenediamine derived from l-serine were used as chiral building blocks, which were combined in the CM step. The most important advantage of this method was the utilization of l-serine as a cheap, stereoisomerically pure substrate. A steroid with a diamino system in the side chain was subjected to reaction with potassium tetrachloroplatinate to obtain the target platinum(II) complex. Attempts to synthesize similar diamine systems using the asymmetric Strecker reaction were unsuccessful.     

Host-guest effect on chirality transfer from a binaphthyl derivative to a host nematic liquid crystal

A novel dichiral compound possessing both an asymmetric axis and a chiral centre induces opposite twist senses and distinct helical pitches in different host nematic liquid crystals; the host-guest effect on chirality transfer is discussed in terms of molecular recognition.     

New cyclitol derivative from a sponge Sarcotragus species

Guided by the brine shrimp lethality assay, a new cyclitol derivative, sarcotride D (1), was isolated from a marine sponge Sarcotragus species. The structure was established based on NMR and MS analyses.     

Tetraaddition of PhLi to a ketocalixarene derivative

[reaction: see text] Reaction of a ketocalixarene with 2.2 equiv or an excess of PhLi affords diaddition and tetraaddition products, respectively. Ionic hydrogenation of the tetraalcohol 8a yields a calix[4]arene monosubstituted by phenyl groups at all four methylene bridges.     

一个苯并咪唑衍生物的基于晶态-晶态转变的余辉刺激响应行为

通过苯并咪唑-5,6-二羧酸和间氨基苯磺酸的缩合得到有机物3-(5,7-dioxoimidazo[4,5-f]isoindol-6(1H,5H,7H)-yl) benzenesulfonic acid (DIBS),进而通过在不同温度下重结晶获得2种固态相： DIBS (10℃)和DIBS (60℃)。DIBS (10℃)具有寿命为721.55 ms的绿色室温磷光,而DIBS (60℃)的黄绿色余辉由寿命分别为259.78和336.33 ms的延迟荧光和室温磷光组成。2种相的不同发光行为可归因于DIBS分子在2种相中不同的构型及堆积结构。有趣的是,在研磨或加热刺激下,DIBS (10℃)可转变为DIBS (60℃),显示出罕见的余辉刺激响应行为。     

Transfer of tetra-n-alkylammonium ions from water to nitrobenzene: Chronopotentiometric determination of kinetic parameters

The transfer from water to nitrobenzene of tetraethylammonium (TEA), tetrapropyl-ammonium (TPA) and tetrabutylammonium (TBA) ions is investigated under galvanostatic conditions. The current density range extends from 10 to 100 μA cm^?2. A treatment similar to that which is already established in the chronopotentiometric study of the metal—solution semi-reversible electrochemical process is applied for the determination of the kinetic parameters of the water—nitrobenzene ion transfer.     

Synthesis of highly fluorescent diketopyrrolopyrrole derivative and two-step response of fluorescence to acid

A highly fluorescent diketopyrrolopyrrole derivative with amino groups was synthesized from Pigment Red 254 by a Pd-catalyzed amination reaction. The amino-substituted diketopyrrolopyrrole exhibits a two-step response of fluorescence depending on acidity. This optical property can be applied to a colorimetric detection of acids in the gas phase.     

2-Hydroxy-5-nitrobenzyl as a diazeniumdiolate protecting group: application in NO-releasing polymers with enhanced biocompatibility

The 2-hydroxy-5-nitrobenzyl group is shown to be an effective protecting group for diazeniumdiolates. O(2)-(2-hydroxy-5-nitrobenzyl)-substituted diazeniumdiolates display enhanced thermal stability, but efficiently release nitric oxide (NO) in pH 7.4 aqueous solutions. A lipophilic analogue incorporated into hydrophobic polymers shows NO surface flux rates comparable to that of the natural endothelium. Importantly, these polymer formulations also show significantly enhanced biocompatibility in vivo with use of a porcine implant model.     

Eucleanal: a new napthalene derivative from Euclea divinorum

A new naphthalene derivative, named eucleanal (1), was isolated from Euclea divinorum Hiern., and its structure elucidated by detailed spectroscopic (1H, 13C NMR, COSY, HMQC, HMBC) and HREIMS analysis.     

Justicidone, a novel p-quinone-lignan derivative from Justicia hyssopifolia

An uncommon, previously unreported p-quinone-lignan compound called justicidone (4-(1,3-benzodioxol-5-yl)-6-methoxynaphtho[2,3-c]furan-1,5,8(3H)-trione) (2), along with the known savinin (1) were isolated from Justicia hyssopifolia (Acanthaceae). Their structures were determined by spectroscopic methods.     

Cysteine-S-trityl a key derivative to prepare N-methyl cysteines

S-Trt Cys are used as precursors for the synthesis of protected NMe-Cys. N-Methylation of Alloc-Cys(Trt)-OH and Boc-Cys(Trt)-OH gives the corresponding N-methylated derivatives in good yields and purities, which can be further derivatized in solution to obtain a myriad of S-protected derivatives. To further broaden the scope of this methodology, the N (alpha)-amino protecting group of the NMe- S-protected Cys can be replaced easily either on the solid phase (from the Alloc precursor) or in solution (from the Boc precursor). Thus, this convenient route allows us to obtain many different protected NMe-Cys, which were of limited accessibility until now.