SPECTROSCOPIC STUDIES OF CUTANEOUS PHOTOSENSITIZING AGENTS. XVIII. INDOMETHACIN

Abstract— The photochemistry, photophysics, and photosensitization (Type I and II) of indomethacin (IN) (N-[p-chlorobenzoyl]-5-methoxy-2-methylindole-3-acetic acid) has been studied in a variety of solvents using NMR, high performance liquid chromatography-mass spectroscopy, transient spectroscopy, electron paramagnetic resonance in conjunction with the spin trapping technique, and the direct detection of singlet molecular oxygen (^l O₂) luminescence. Photodecomposition of IN (λ_ex > 330 nm) in degassed or air-saturated benzene proceeds rapidly to yield a major (2; N-[p-chlorobenzoyl]-5-methoxy-2-methyl-3-methylene-indoline) and a minor (3; N-[p-chlorobenzoyl]-5-methoxy-2, 3-dimethyl-indole) decarboxylated product and a minor indoline (5; 1-en-5-methoxy-2-methyl-3-methylene-in-doline), which is formed by loss of the p-chlorobenzoyl moiety. In air-saturated solvents two minor oxidized products 4 (N-[p-chlorobenzoyl]-5-methoxy-2-methylindol-3-aldehyde) and 6 (5-methoxy-2-methyl-indole-3-aldehyde) are also formed. When photolysis was carried out in ¹⁸O₂-saturated benzene, the oxidized products 4 and 6 contained ¹⁸O, indicating that oxidation was mediated by dissolved oxygen in the solvent. In more polar solvents such as acetonitrile or ethanol, photodecomposition is extremely slow and inefficient. Phosphorescence of IN at 77 K shows strong solvent dependence and its emission is greatly reduced as polarity of solvent is increased. Flash excitation of IN in degassed ethanol or acetonitrile produces no transients. A weak transient is observed at 375 nm in degassed benzene, which is not quenched by oxygen. Irradiation of IN (λ_ex > 325 nm) in N₂-gassed C₆H₆ in the presence of 5, 5-dimethyl-1-pyrroline-N-oxide (DMPO) results in the trapping of two carbon-centered radicals by DMPO. One adduct was identified as DMPO/^.COC₆H₄-p-CI, while the other was probably derived from a radical formed during IN decarboxylation. In air-saturated benzene, (hydro) peroxyl and alkoxyl radical adducts of DMPO are observed. A very weak luminescence signal from ¹O₂ at 1268 nm is observed initially upon irradiation (λ_ex= 325 nm) of IN in air-saturated benzene or chloroform. The intensity of this ¹O₂ signal increases as irradiation is continued suggesting that the enhancement in ¹O₂ yield is due to photoproduct(s). Accordingly, when 2 and 3 were tested directly, 2 was found to be a much better sensitizer of ¹O₂ than IN. In air-saturated ethanol or acetonitrile no IN ¹O₂ luminescence is detected even on continuous irradiation. The inability of IN to cause phototoxicity may be related to its photo stability in polar solvents, coupled with the low yield of active oxygen species (¹O₂, O₂^?_-) upon UV irradiation.     

Simultaneous Kinetic‐Spectrophotometric Determination of Hydrazine and its Derivatives by Partial Least Squares and Principle Component Regression Methods

Simultaneous kinetic‐spectrophotometric determination of a ternary mixture of hydrazine (HZ) and its derivatives by principal component regression (PCR) and partial least squares (PLS) calibration is described. The methods were based on the difference observed in the reduction rate of iron(III) with HZ, thiosemicarbazide (TSCZ) and phenylhydrazine (PHZ) in the presence of 2,2′‐bipyridine (Bpy). The colored complex of [Fe(Bpy)₃]²⁺ was formed in sodium dodecyl sulfate (SDS) as micellar media, and then monitored at 520 nm. The results showed that simultaneous determination of HZ, TSCZ and PHZ could be performed in their concentration ranges of 1.0–70.0, 0.2–6.0 and 0.1–10.0 μg mL^?1, respectively. The root mean squares errors of prediction (RMSEP) of HZ, TSCZ and PHZ were 0.719, 0.164 and 0.105 (for PLS) 0.788, 0.166 and 0.993 (for PCR), respectively. Both methods (PCR and PLS) were validated using a set of synthetic sample mixtures and then applied for simultaneous determination of HZ, TSCZ and PHZ in water samples.     

HPTLC Procedure for Determination of Levonorgestrel in the Drug-Release Media of an In-situ-Forming Delivery System

JPC – Journal of Planar Chromatography – Modern TLC -     

Activities of Individual Ions From Infinite Dilution to Saturated Solutions

A new procedure, which provides a closer approximation for the junction potentials than the Henderson equation, is tested to reduce new emf data for the chloride ion in CsCl solutions and previously measured data for individual ions in aqueous solutions of KCl, NaCl, and NaBr. The liquid junction potential is calculated from numerical integration of its basic equation without assuming constant mobility or using concentrations instead of activities. The mean ionic activity coefficients of the salts, obtained from the activity coefficients of the individual ions, show good agreement with values reported in the literature. The activity coefficients of the individual chloride ion at 25°C in aqueous solutions of CsCl up to 3 molal and in KCl solutions were measured using a chloride ion-selective electrode. It has been confirmed that the activity of the chloride ion is equal to the activity of the cation in CsCl solutions and, contrary to the prediction of hydration theory, it is higher than the activity of the cation in aqueous KCl solutions. The New Hydration Theory has been developed to overcome the shortcomings of the older hydration theory and has been used to smooth the experimental activity coefficients of the individual ions in aqueous solutions and to extrapolate them up to the saturated solution.     

Ketoconazol‐Triiodide Ion Pair Complex as a Suitable Carrier in an Iodide Selective Membrane Electrode

A novel membrane sensor for selective monitoring of iodide, consisting of a triiodide‐ketoconazole ion pair complex dispersed in a PVC matrix, plasticized with a mixture of 2‐nitrophenyl octyl ether and dioctylphtalate with unique selectivity toward iodide ions, is described. The influence of membrane composition, pH of test solution and foreign ions on the electrode performance were investigated. The optimized membrane demonstrates a near‐Nernstian response for iodide ions over a wide linear range from 1.0 × 10^?2 to 1.0 × 10^?5 M, at 25 ± 1 °C. The electrode could be used over a wide pH range 3–10 and has the advantages of high selectivity, fast response time and good lifetime (over 4 months). It was successfully used as indicator electrode in potentiometric titrations and direct potentiometric assay of iodide ions.     

One-pot Three-component Condensation Reactions in Water. An Efficient and Improved Procedure for the Synthesis of Furan Annulated Heterocycles

Summary. The environment-friendly one-pot three-component condensation reactions of 4-hydroxycoumarin or 4-hydroxy-6-methylpyrone, p-substituted benzaldehyde, and alkyl or aryl isocyanides to afford furocoumarines or furopyranones in water in good yields after about one hour at 75°C are reported.     

New computer program to calculate the symmetry of molecules

In this paper we, present some MATLAB and GAP programs and use them to find the automorphism group of the Euclidean graph of the C₈₀ fullerence with connectivity and geometry of I _h symmetry point group. It is proved that this group has order 120 and is isomorphic to I _h ≊Z₂×A₅, where Z₂ is, a cyclic group of order 2 and A₅ is the alternating group on five symbols.     

Die Reaktion von Tellurhexafluorid mit Trimethylamin,Strukturen der TeF5−- und SeF5−-Anionen

Reaction of Telluriumhexafluoride and Trimethylamine, Structures of the TeF₅^? and SeF₅^? Anions The reaction of TeF₆ and (CH₃)₃N is of the redox kind, resulting in reduction of tellurium: X-ray single crystal analysis reveals the compounds (CH₃)₂N? CH₂? N(CH₃)₂⁺TeF₅^? and [(CH₃)₃NH⁺]₅(TeF₅^?)₃(HF₂^?)₂. By comparison with published data it can be shown that this mixture is identical to previously published [(CH₃)₃N]₂TeF₆. The latter was supposed to be one of the few examples of tellurium in a coordination state of eight. (CH₃)₄N⁺TeF₅^? and (CH₃)₄N⁴SeF₅^? are obtained and their structure is investigated by single crystal x-ray methods also. The anions SF₅^?, SeF₅^? and TeF₅^? are discussed in terms of weak interactions.     

Solid State Regeneration of Carbonyl Compounds from Oximes and Semicarbazones with Poly [N‐Bromo‐Benzene‐1,3‐Disulfonylamide]

Poly [N‐bromo‐benzene‐1,3‐disulfonylamide] [ PBBS ] is a novel and efficient reagent for the conversion of oximes and semicarbazones under solid state to their corresponding carbonyl compounds in high yields.     

Gravitomagnetic Effects on Collective Plasma Oscillations in Compact Stars

The effects of gravitomagnetic force on plasma oscillations are investigated using the kinetic theory of homogeneous electrically neutral plasma in the absence of external electric or magnetic field. The random phase assumption is employed neglecting the thermal motion of the electrons with respect to a fixed ion background. It is found that the gravitomagnetic force reduces the characteristic frequency of the plasma thus enhancing the refractive index of the medium. The estimates for the predicted effects are given for a typical white dwarf, pulsar, and neutron star.