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UV absorbers for treating cotton textiles with the aim of increased protection against harmful effects of UV component of solar radiation have been prepared by reactions of five different aminophenylsulfobenzotriazoles with the condensation product of 4-aminophenyl-sulfatoethylsulfone and cyanuric chloride. The UV absorbers with two different reactive groups (monochlorotriazine and aromatic vinylsulfone), capable of formation of covalent bonds with hydroxyl groups of cellulose, were applied to one cellophane foil and two cotton fabrics of different porosities. This treatment increased the ultraviolet protection factor from a value of UPF 5 3 to UPF 5 100 and above. For attaining a high UPF value, the cotton material should exhibit low porosity. The UV absorbers with 2-hydroxyphenyl group are stable in light and do not fluoresce on the fabric on contrary to derivatives without 2-hydroxyphenyl group or with 2-methoxyphenyl group. The high photostability of absorbers is explained by the possibility to disperse the absorbed energy of UV radiation in the form of harmless energy such as IR radiation (heat) through the reversible hydrogen bond between phenolic hydroxyl group and triazine cycle. The UV filters block the effect of optical brightening agents on cotton by quenching the fluorescence.

The reaction between 5‐nitro‐2,1‐benzisothiazole‐3‐diazonium species and N‐substituted anilines produces the 1‐(5‐nitro‐2,1‐benzisothiazol‐3‐yl)‐3,3‐disubstituted triazenes 1. These triazenes are highly stable, and even in strongly acidic medium (0.5 mol⋅L−1 H2SO4) they are only slowly decomposed back to the diazonium ion and substituted anilinium ion (for the N‐ethyl derivative in 0.5 mol·L−1 H2SO4 at 25 °C, t1/2 ≈︁ 7 h). A series of six triazenes were characterised by their 1H and 13C NMR spectra and mass spectra. Two of the triazenes were also identified by X‐ray crystallography. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

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Occurrence of radical molecular ions in atmospheric pressure chemical ionization mass spectra of heterocyclic compoundsIt is well-known that the use of atmospheric pressure ionization (API) techniques, such as electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI), is associated with the formation of even-electron ions, 1 for example, protonated molecules [M C H] C , adducts with alkali metal ions [M C Na] C and [M C K] C , adducts with ammonium ions [M C NH 4 ] C in the positive-ion mode and deprotonated molecules [M H] and some adducts with small inorganic anions in the negative-ion mode. The relative abundances of fragment ions are generally low to negligible and mostly they have also even number of electrons, otherwise even-electron rule would be contradicted. Odd-electron ions do not typically occur in ESI/APCI mass spectra, but some exceptions are known, 2 for example, radical molecular ions M ž formed by an electron capture 3 or charge exchange mechanisms 4,5 in the negative-ion APCI mode, and radical molecular ions M C ž formed by the charge exchange mechanism in case of nonpolar polyaromatic hydrocarbons. 6,7 In the present communication, we would like to highlight few well-pronounced examples on the formation of radical molecular ions both in the positive-ion and negative-ion APCI modes using an ion trap Esquire 3000 (Bruker Daltonics, Bremen, Germany) or a single quadrupole Platform (Micromass, Manchester, UK) under the following experimental conditions: the mass range m/z 50-1000, the target mass m/z 250 and the compound stability 20% for alkyl series from C2 to C4, the target mass m/z 350 and the compound stability 100% for alkyl series from C5 to C10, pressure of the nebulizing gas 15 psi, the drying gas flow rate 4 l/min, temperature of the ion source 350°C and temperature of drying gas 300°C. The samples were dissolved in acetonitrile and delivered into the system by an infusion pump at the flow rate of 5 µl/min. In some experiments, different solvents (methanol, benzene, or water) were used to compare results with the measurements in acetonitrile.Unlike the conventional electron ionization, the formation of odd-electron molecular ions is quite unusual in API mass spectra. The preference of radical ion formation depends on the structure, the ionization mode, and the experimental conditions, for example solvents used for the analysis. In ESI, the occurrence of molecular radical ions is very rare and it is usually attributed to the electrochemical processes on the electrospray needle or different oxidation states of metal ions. On the other hand, the presence of radical molecular ions in the latest API technique, atmospheric pressure photoionization (APPI), is relatively common due to the different ionization mechanism. 5 The presence of molecular radical ions is not typical for APCI, but some examples have been reported for polyaromatic hydrocarbons without other functionalities in the positive-ion mode 6,7 or for compounds with the high electron affinity and low gas-phase...