Synthesis of New Spiropyrans With a Polyaromatic or Heteroaromatic Pendant and Their Photochromic Bedhaviors

A series of spiropyrans with a polyaromatic or heteroaromatic pendant was synthesized conveniently.Their photochromic behaviors were investigated with the aid of absorption spectral measurements.The results indicated that the compounds with the same parent spiropyran but different aromatic pendant show significantly different photochromic properties.This may be due to the π-π orbital interaction between the polyaromatic pendant and the open photomerocyanine form of spiropyran.The results obtained are very useful in the molecule design area.     

Destructive adsorption of CCl4 over lanthanum-based solids: linking activity to acid-base properties

The relative activities of a low-surface crystalline and high-surface amorphous LaOCl, further denoted as S1 and S2, have been compared for the destructive adsorption of CCl4. It was found that the intrinsic activity of S2 is higher than that of S1. Both samples were characterized with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2-physisorption, and Raman and infrared (IR) spectroscopy. IR was used in combination with CO2, CO, and methanol as probe molecules. The CO2 experiments showed that different carbonate species are formed on both materials. For S1, a high surface concentration of bidentate carbonate species and a lower concentration of monodentate carbonate were observed. In the case of S2, bulk carbonates were present together with bridged carbonates. CO adsorption shows that S2 and S1 have very similar Lewis acid sites. However, methanol adsorption experiments showed that S2 had a higher number of stronger Lewis acid sites than S1 and that twofold coordinated methoxy species were more strongly bound than threefold coordinated methoxy species. Because of the analogy between methanol dissociation and the removal of the first chlorine atom in the destructive adsorption of CCl4, the sites enabling twofold coordination were likely to be the same Lewis acid sites actively involved in the destructive adsorption of CCl4. La2O3 was less active than the two LaOCl materials, and therefore, the intrinsic activity of the catalyst increases as the strength of the Lewis acid sites increases. S2 contains more chlorine at the surface than S1, which is expressed by the higher number of sites enabling twofold coordination. Moreover, this explains the difference in destructive adsorption capacity for CCl4 that was observed for the samples S1 and S2. Since LaCl3, being the most acidic phase, is not active for the destructive adsorption of CCl4, basic oxygen atoms, however, remain needed to stabilize the reaction intermediate CCl3 as La-O-CCl3.     

On-line determination of carboxylic acids, aldehydes and ketones by high-performance liquid chromatography-diode array detection-atmospheric pressure chemical ionisation mass spectrometry after derivatization with 2-nitrophenylhydrazine

2-Nitrophenylhydrazine (2-NPH) is widely used for the derivatization of carboxylic acids, aldehydes and ketones, in industrial and biological samples. These compounds react with 2-NPH to form derivatives, which are separated by high-performance liquid chromatography (HPLC) and detected with diode array detection (DAD). The UV spectra give information about the functionality of the compounds: carboxylic acid or ketone/aldehyde. Most of the eluting compounds in "known" samples are well characterised by the retention time (comparison with those of standards) of the 2-NPH derivative and their UV spectrum. The identification of different unknown 2-NPH derivatives of carboxylic acids, ketones and/or aldehydes, in industrial or biological samples, based on retention time and/or UV spectrum is not sufficient. These unknown 2-NPH compounds can be identified with on-line atmospheric pressure chemical ionisation mass spectrometry (APCI-MS) based on the molecular mass or/and the fragmentation of the derivative. A novel and specific on-line HPLC-DAD-APCI(-)-MS method is described for the determination of carboxylic acids, ketones and aldehydes, after on-line pre-column derivatization with 2-NHP. The fragmentation of different 2-NPH derivatives were investigated and the possibilities of APCI(-)-MS detection were demonstrated by the on-line identification of an unknown derivative, which turned out to be a side product between 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 2-NPH in the presence of high concentrations of a cyclic amide in the sample solution.     

A new approach in assessing microbiological results in water analysis proficiency testing

Due to the relatively large spread in the results of microbiological proficiency tests, the z-scores are often not able to detect zero or low results as being ‘bad’ results. This paper describes an adapted z-score based on the average or the standard deviation of the 50% ‘highest’ results. The combination of the adapted z-scores of four samples enables a better judgement of the performance of each laboratory. Papers published in this section do not necessarily reflect the opinion of the Editors, the Editorial Board or the Publisher.     

Simultaneous flow injection determination of ammoniacal nitrogen and chloride in industrial effluent water with a combined on-line gas diffusion/dialyser unit

An on-line gas diffusion/dialyser unit has been designed and incorporated into the manifold of a flow injection system for the simultaneous determination of two different species in a single sample injected into the FIA system. A fast and reliable fully automated two-component flow injection procedure has been carried out where a single sample (50 l industrial effluent water) is injected into a carrier stream and simultaneously gas diffused and dialysed in a single on-line gas diffusion/dialyser unit for the determination of ammonia and chloride, respectively. The results obtained for the ammoniacal nitrogen and chloride in industrial effluent water compared well with data obtained by standard methods. The relative standard deviation for industrial effluent water samples with concentrations of ammoniacal nitrogen in the range between 0.050 and 1 g/l and chloride from 0.127 to 2.531 g/l have been better than 1.0% for ammoniacal nitrogen and 0.5% for chloride, respectively. The proposed system could be attractive for routine analyses of industrial effluent water.     

Photobinding of 8-methoxypsoralen, 4,6,4'-trimethylangelicin and chlorpromazine to Wistar rat epidermal biomacromolecules in vivo.

Photoinduced binding of drugs to endogenous biomacromolecules may cause both toxic and therapeutic effects. For example, photobinding of certain phenothiazines to biomolecules possibly underlies their phototoxic and photoallergic potential, whereas photobinding of furocoumarins to epidermal DNA is held responsible for their advantageous effects in the photochemotherapy of psoriasis. Usually, the in vitro photobinding of drugs is investigated. However, under in vivo conditions, the metabolism and distribution of the drug and the light absorption by endogenous compounds will significantly affect the photobinding of drugs to biomolecules. Therefore, in the present study, the photobinding of 8-methoxypsoralen (8-MOP), 4,6,4'-trimethylangelicin (TMA) (two therapeutically used furocoumarins) and chlorpromazine (CPZ) (a member of the phenothiazines) was investigated in vivo. The compounds were applied topically on the shaven skin of Wistar rats; one group was exposed to UVA and the other was kept in a dimly lit environment. Immediately, and at certain time intervals after UVA exposure, members of the two groups were sacrificed. By separating epidermal lipids, DNA/RNA and proteins by a selective extraction method, irreversible binding of 8-MOP, TMA or CPZ to each of these biomacromolecules was determined. In contrast with in vitro experiments, photobinding of CPZ to epidermal DNA/RNA was not found in vivo; apparently the bioavailability in the nucleus is very low. Compared with TMA, 8-MOP was observed to bind more extensively to epidermal DNA/RNA (again in contrast with findings from in vitro experiments) and proteins, but less extensively to lipids. The rates of removal of photobound 8-MOP and TMA were comparable. Photobound CPZ was more slowly removed from epidermal proteins and lipids than the furocoumarins. The observed in vivo photobinding is discussed with respect to the UVA-induced (side) effects of these drugs.     

Analysis of impact-excited HeI states by applying magnetic and electric depolarization techniques

The magnetic depolarization of the impact radiation at λ(4¹ D?2¹ P)=492 nm and λ(3¹ D?2¹ P) = 668 nm as well as the splitting of the magnetic depolarisation signals in electric fields were investigated for 10–25 keV H ₂ ⁺ (D ₂ ⁺ )-He collisions (only 492 nm line) and for 5-22.5 keV He-He collisions (both lines). The results are compared with analogous measurements for He⁺- He and Ne⁺ - He collisions and the dynamics of the excitation process are qualitatively discussed. In particular, we emphasize the importance of inertia for the evolution of the electron cloud during the final phase of the collision process.     

The identification of flunitrazepam and its metabolites in urines samples

A thin-layer chromatographic method with fluorescence detection is described for the identification of flunitrazepam and its metabolites in urine. The method is based on the hydrolysis and subsequent formation of acridine derivatives by cyclization in dimethylformamide and is selective for benzodiazepines with a 2-fluorophenyl group. The method is applicable to urine samples even after an oral dose of only 2 mg of flunitrazepam. Flunitrazepam and flurazepam consumption can be distinguished.     

Synthesis of 5′‐O‐(2‐Azido‐2‐deoxy‐α‐D‐glycosyl)nucleosides and Their Antitumor Activities

The 1,3,4,6‐tetra‐O‐acetyl‐2‐azido‐2‐deoxy‐β‐D ‐mannopyranose ( 4 ) or the mixture of 1,3,6‐tri‐O‐acetyl‐2‐azido‐2‐deoxy‐4‐O‐(2,3,4,6‐tetra‐O‐acetyl‐β‐D ‐galactopyranosyl)‐β‐D ‐mannopyranose ( 10 ) and the corresponding α‐D ‐glucopyranose‐type glycosyl donor 9 / 10 reacted at room temperature with protected nucleosides 12 – 15 in CH₂Cl₂ solution in the presence of BF₃?OEt₂ as promoter to give 5′‐O‐(2‐azido‐2‐deoxy‐α‐D ‐glycosyl)nucleosides in reasonable yields (Schemes 2 and 3). Only the 5′‐O‐(α‐D ‐mannopyranosyl)nucleosides were obtained. Compounds 21, 28, 30 , and 31 showed growth inhibition of HeLa cells and hepatoma Bel‐7402 cells at a concentration of 10 μM in vitro.