Jadwiga Rzeszotarska

Anomalous (S2 → S0) luminescence of some derivatives of triphenylmethane dyes and their complexes with rare earth metals

Abstract Anomalous S 2 → S 0 fluorescence and T 2 → S 0 phosphorescence have been found in several triphenylmethane derivatives. This phenomenon can be explained by a large energy gap between the S 2 and S 1 levels, approximately 14000 cm −1 . Some of the investigated compounds exhibit also a normal long-wave fluorescence in spite of the fact, that the S 2 − S 1 energy gap does not change significantly. However, in these cases absorption spectra reveal a high oscillator strength of the S 1 → S 0 transition. The coordination of a lanthanide ion quenches in several cases the normal S 1 → S 0 fluorescence whereas the S 2 → S 0 one is not affected significantly.

Spectrophotometric studies on the solvatochromism of the Fe(CN)2(phen)2 complex

SummaryThe solvatochromic behaviour ofbis-(cyano)-bis-(9,10-phenanthroline)-iron(II) has been reexamined spectrophotometrically in a series of 19 solvents including water, alcohols and dipolar. aprotic media. Satisfactory correlations between the wave numbers of the long-wavelength band and solvent acceptor numbers are obtained in all media; only values, for carboxylic acids deviate from the regression line.ZusammenfassungDas solvatochrome Verhalten vonbis-(Cyano)-bis-(9,10-phenanthrolin)-eisen(II) wurde in 19 Lösungsmitteln, darunter Wasser, Alkohole und dipolare aprotische Medien, spektrophotometrisch überprüft. In allen Medien wurden zufriedenstellende Korrelationen zwischen den Wellenzahlen der langwelligen Bande und den Akzeptorzahlen der Lösungsmittel erhalten; lediglich die Werte für Carbonsäuren weichen von der Ausgleichgeraden ab.

POLAROGRAPHIC STUDY OF TL+, LI+, NA+, K+, AND CS+ COMPLEXES WITH MONENSIN ANION IN DIPOLAR APROTIC SOLVENTS

SummaryThe stability constants,Ksof monensin complexes with Li+, Na+, K+ and Cs+ ions were studied by a competitive polarographic method using the Tl+/Tl(Hg) redox couple as a sensitive electrochemical probe. TheKsvalues are strongly influenced by the solvents (acetonitrile, propionitrile, acetone, N,N-dimethylformamide, N-methyl pyrolidinone, N,N-dimethylacetamide, dimethylsulfoxide, N,N-diethylformamide and N,N-diethylacetamide were used in experiments) and vary inversely with the Gutmann donicity scale. Molecular mechanics computations revealed the probable structures of the complexes.ZusammenfassungEs wurden die StabilitätskonstantenKsvon Monesin-Komplexen mit Li+-, Ma+- und Cs+-Ionen mittels einer competitiven polarographischen Methode unter Verwendung der Tl+/Tl(Hg)-Redoxelektrode als sensitiver elektrochemischer Sonde bestimmt. DieKs-Werte werden stark vom Lösungsmittel (Acetonitril, Propionitril, Aceton, N,N-Dimethylformamid, N-Methylpyrrolidinon, N,N-Dimethylacetamid, Dimethylsulfoxid, N,N-Diethylformamid und N,N-Diethylacetamid) beeinflußt, wobei sie invers zurGutmann schen Donizitätsskala variieren. Die wahrscheinliche Struktur der Komplexe wurde mittels molekularmechanischer Berechnungen ermittelt.

Acoustic emission signals from the sol–gel transition of tetraethoxysilan (TEOS) and sodium silicate solutions

Sol–gel processes have been used extensively to prepare oxide materials (glasses and ceramics). The acoustic emission (AE) method with broadband piezoelectric transducer (up to 500 kHz) was used to control the evolution of slow gel formation from organic TEOS and fast formations from sodium silicate as the precursors of silica. The obtained dependencies of the AE count rate and rms values versus time characterize the dynamic of the cross‐linking and desolvation processes under ambient conditions. The frequency distribution analysis of individual power spectra provides an activity estimation of integral parts of processes. In sodium silicate solutions the spectra of low frequency (17–70 kHz) were mainly observed. On the other hand, the most representative spectra from the gelation of TEOS display at three basic ranges; 16–20 kHz, 200–230 kHz, and 400–470 kHz. The relative intensities of spectra in these ranges were changed considerably during the gel formation. [Work partly supported by KBN Grant No. T 07B...

Photoacoustic cells for liquids and solids investigation

The photoacoustic (PA) cell containing the sample of material under investigation is considered as one among the most important parts of the photoacoustic spectroscope. Examples of newly designed cells for liquids and solids investigation are presented. The special photoacoustic cell for laser beam intensity measurement, together with its preliminary test results, is described.

Investigations of the luminescence of N-alkenylcarbazoles and their charge-transfer complexes with 2,4,7-trinitro-9-fluore-none and 7,7,8,8-tetracyanoquinodimethane

Abstract The efficiency of flourescence quenching of N-alkenylcarbazoles was higher for TCNO than for TNF and increased with the carbon chain lenght. The flourescence of CT complexes of N-alkenylcarbazoles consisted of two superimposed bands corresponding to two orientational isomers. The energy distribution in the CT band depended on the excitation wavelenth.