Studies on the Reaction of α‐Chloroformylarylhydrazine Hydrochloride with Imidazole and 1,2,4‐Triazole

α‐Imidazolformylarylhydrazine 2 and α‐[1,2,4]triazolformylarylhydrazine 3 have been synthesized through the nucleophilic substitution reaction of 1 with imidazole and 1,2,4‐triazole, respectively. 2,2′‐Diaryl‐2H,2′H‐[4,4′]bi[[1,2,4]‐triazolyl]‐3,3′‐dione 4 was obtained from the cycloaddition of α‐chloroformylarylhydrazine hydrochloride 1 with 1,2,4‐triazole at 60 °C and in absence of n‐Bu₃N. The inducing factor for cycloaddition of 1 with 1,2,4‐triazole was ascertained as hydrogen ion by the formation of 4 from the reaction of 3 with hydrochloric acid. 4 was also acquired from the reaction of 3 with 1 and this could confirm the reaction route for cycloaddition of 1 with 1,2,4‐triazole. Some acylation reagents were applied to induce the cyclization reaction of 2 and 3.1 possessing chloroformyl group could induce the cyclization of 2 to give 2‐aryl‐4‐(2‐aryl‐4‐vinyl‐semicarbazide‐4‐yl)‐2,4‐dihydro‐[1,2,4]‐triazol‐3‐one 6. 7 was obtained from the cyclization of 2 induced by some acyl chlorides. Acetic acid anhydride like acetyl chloride also could react with 2 to produce 7D . 5‐Substituted‐3‐aryl‐3H‐[1,3,4]oxadiazol‐2‐one 8 was produced from the cyclization reaction of 3 induced by some acyl chlorides or acetic acid anhydride. The 1,2,4‐triazole group of 3 played a role as a leaving group in the course of cyclization reaction. This was confirmed by the same product 8 which was acquired from the reaction of 1 , possessing a better leaving group: Cl, with some acyl chlorides or acetic acid anhydride.     

Optical excitation and absorption spectra of C50Cl10

C50Cl10 [S. Y. Xie et al., Science 304, 699 (2004)] has been synthesized in large quantities enabling the capture of the labile fullerene C50. In this Communication, we report ab initio calculations on the optical excitation and absorption spectra of C50Cl10. We successfully explain and assign the measured UV-visible absorption spectrum of C50Cl10. The first singlet excitation for C50Cl10 is optically forbidden, and its optical absorption gap is redshifted by 0.6 eV (110 nm) relative to that of C60. We demonstrate that passivating C50 with 10 hydrogen atoms and replacing one Cl in C50Cl10 by one methoxy group lead to 100 nm blueshift and 90 nm redshift of the optical gap predicted for C50Cl10, respectively, suggesting C50 derivatives are suitable for tunable optical applications.     

Electron-transfer transitions during the collision of O2, N2, NO and CO with their respective ions

An improved theory of electron transfer absorption is proposed. The possibility of such absorption during the collision of ion-molecule pairs is discussed and frequencies for the O₂O₂⁺, O₂O₂^?, NONO^?, COCO⁺ and N₂N₂⁺ pairs are estimated. Oscillator strengths are also estimated for the O₂O₂⁺ pair.     

Comparing micellar electrokinetic chromatography and microemulsion electrokinetic chromatography for the analysis of preservatives in pharmaceutical and cosmetic products

In this study, separation and determination of nine preservatives ranging from hydrophilic to hydrophobic properties, which are commonly used as additives in various pharmaceutical and cosmetic products, by micellar electrokinetic chromatograpy (MEKC) and microemulsion electrokinetic chromatography (MEEKC) were compared. The effect of temperature, buffer pH, and concentration of surfactant on separation were examined. In MEKC, the separation resolution of preservatives improved markedly by changing the sodium dodecyl sulfate concentration. Temperature and pH of running buffers were used mainly to shorten the magnitude of separation time. However, in order to detect all preservatives in a single run in a MEEKC system, a microemulsion of higher pH was needed. The separation resolution was improved dramatically by changing temperature, and a higher concentration of SDS was necessary for maintaining a stable microemulsion solution, therefore the separation of the nine preservatives in MEEKC took longer than in MEKC. An optimum MEKC method for separation of the nine preservatives was obtained within 9.0 min with a running buffer of pH 9.0 containing 20 mM SDS at 25 degrees C. A separation with baseline resolution was also obtained within 16 min using a microemulsion of pH 9.5 which composed of SDS, 1-butanol, and octane, and a shorter capillary column at 34 degrees C. Finally, the developed MEKC and MEEKC methods determined successfully preservatives in various cosmetic and pharmaceutical products.     

Theory of vibrationally coupled pairwise charge transfer in a linear conjugated molecular chain

A model describing the electron charge transfer along a linear conjugated molecular chain based on a double harmonic oscillator picture is presented. Qualitatively, the model predicts three temperature regions of distinct conductivity characteristics: semiconductor-like (low temperature, TR-A), metal-like (high temperature, TR-C) and a narrow transition temperature region (TR-B) between the above two. In ideal cases, where the π-bond transfer frequency ω, coincides with the antisymmetric normal model of vibration frequency, υ, a cooperative pairwise charge transfer (“covalon”) is expected to take place leading to an anomalously high conductivity.     

Control of nanoparticle location in block copolymers

A simple procedure is described to incorporate gold nanoparticles and control their location within symmetric poly(styrene-b-2 vinyl pyridine) (PS-PVP) diblock copolymers. Gold nanoparticles coated with thiol-terminated PS and/or PVP homopolymer chains (Mn approximately 1300 and 1500 g/mol, respectively) are incorporated into alternating lamellar layers of PS and PVP (total Mn approximately 196 500 g/mol). The location of the particles is controlled by varying the composition of ligands on the particle surfaces. In particular, gold particles coated with 100% PS or PVP reside near the center of the respective polymer domains, while particles coated with a mixture of both homopolymers reside at the interfaces between the two blocks.     

Chemical constituents of Antrodia camphorata submerged whole broth

One new compound, 10-hydroxy-gamma-dodecalactone (1) and three natural new compounds, 11-hydroxy-gamma-dodecalactone (2), 2-(2-hydroxyethyl)phenol (3) and 12-hydroxydodecanoic acid methyl ester (4), together with eight known compounds, ergostatrien-3beta-ol, ergosterol peroxide, methyl (4-hydroxyphenyl)acetate, vanillin, 4-hydroxybenzaldehyde, hexadecanoic acid, 5-methoxymethylfuran-2-carbaldehyde and 5-hydroxymethylfuran-2-carbaldehyde, all were isolated from the submerged whole broth of Antrodia camphorata. The structures of 1 and 2 were principally elucidated by spectral evidence and the absolute configuration was elucidated by the modified Mosher's method.     

Composite nano-titanium oxide-chitosan artificial skin exhibits strong wound-healing effect-an approach with anti-inflammatory and bactericidal kinetics

A composite nano-TiO2-chitosan with collagen artificial skin (NTCAS) showed promising characteristics of moderate water absorptivity (110 wt.-%), fine thickness (0.34 mm), low density (0.33 mg x mm(-3)), moderate biodegradability (<3.0%), and favorable time-dependent biodegradability (0.0521 mg x mL(-1) x h(-1) on Day 0; 0.0006 mg x mL(-1) x h(-1)on Day 3 post covering). More importantly, it showed uniquely potent bactericidal (sterilization) property with relatively large values of pseudo first-order kinetic coefficients (0.1736-0.0360 min(-1)) for TiO2 contents ranging from 2.63 x 10(-5) to 2.11 x 10(-4) mg x cm(-2). In wounded subjects, NTCAS showed a steady level of TNF-alpha, while the IL-6 level reached a peak on Day 7, although significantly lower than in the control and Duoderm groups. In the animal model, NTCAS showed better and faster recovery than the other groups, which can be attributed to the unique bactericidal effect of nano-TiO2 and immune-enhancing effect of chitosan. NTCAS is a promising artificial skin substitute and is superior to any other market product currently in use.     

Synthesis and characterization of Cu(I) and Cu(II) complexes containing ketiminate ligands

A series of Cu(I) and Cu(II) complexes containing substituted ketiminate ligands was synthesized. Reaction of CuCl₂ with 2 equiv. of Li[OC(Me)CHC(Me)N(Ar)] in toluene generated dark green solid of Cu[OC(Me)CHC(Me)N(Ar)]₂ (1). Similarly, Cu(I) complex, {Cu[OC(Me)CHC(Me)N(Ar)]Li[OC(Me)CHC(Me)N(Ar)]}₂ (2) was synthesized by reacting 2 equiv. of Li[OC(Me)CHC(Me)N(Ar)] with CuCl in toluene at room temperature for 12 h. While the reaction of CuCl with Li[OC(Me)CHC(Me)N(Ar)] in the presence of triphenylphosphine in THF solution at room temperature, a three-coordinated Cu[OC(Me)CHC(Me)N(Ar)](PPh₃) (3) can be isolated in high yield. Replacing the PPh₃ of 3 with N-heterocarbene (NHC) generates Cu[OC(Me)CHC(Me)N(Ar)](NHC) (4) in low yield. Complexes 2, 3, and 4 were characterized by ¹H and ¹³C NMR spectroscopies and all molecules were structurally characterized by X-ray diffractometry. Two coordination modes of ketiminate ligands were found in the molecular structure of 2, one of which is copper-coordinated terminal ketiminates and the other is lithium-copper-coordinated bridging ketiminates.     

The death of human cancer cells following photodynamic therapy: apoptosis competence is necessary for Bcl-2 protection but not for induction of autophagy

Photodynamic therapy (PDT) is an efficient inducer of apoptosis in many types of cells, except in cells deficient in one or more of the factors that mediate apoptosis. Recent reports have identified autophagy as a potential alternative cell death process following PDT. Here we investigated the occurrence of autophagy after PDT with the photosensitizer Pc 4 in human cancer cells that are deficient in the pro-apoptotic factor Bax (human prostate cancer DU145 cells) or the apoptosis mediator caspase-3 (human breast cancer MCF-7v cells) and in apoptosis-competent cells (MCF-7c3 cells that stably overexpress human pro-caspase-3 and Chinese hamster ovary CHO 5A100 cells). Further, each of the cell lines was also studied with and without stably overexpressed Bcl-2. Autophagy was identified by electron microscopic observation of the presence of double-membrane-delineated autophagosomal vesicles in the cytosol and by immunoblot observation of the Pc 4-PDT dose- and time-dependent increase in the level of LC3-II, a component of the autophagosomal membrane. Autophagy was observed in all of the cell lines studied, whether or not they were capable of typical apoptosis and whether or not they overexpressed Bcl-2. The presence of stably overexpressed Bcl-2 in the cells protected against PDT-induced apoptosis and loss of clonogenicity in apoptosis-competent cells (MCF-7c3 and CHO 5A100 cells). In contrast, Bcl-2 overexpression did not protect against the development of autophagy in any of the cell lines or against loss of clonogenicity in apoptosis-deficient cells (MCF-7v and DU145 cells). Furthermore, 3-methyladenine and wortmannin, inhibitors of autophagy, provided greater protection against loss of viability to apoptosis-deficient than to apoptosis-competent cells. The results show that autophagy occurs during cell death following PDT in human cancer cells competent or not for normal apoptosis. Only the apoptosis-competent cells are protected by Bcl-2 against cell death.