Solvent effect on the spectral properties of dipolar laser dyes: Evaluation of ground and excited state dipole moments

The effect of solvents on absorption and fluorescence spectra and dipole moments of two medium sized dipolar laser dyes 2-(2,7-dichloro-6-hydroxy-3-oxo-3H-xanthen-9-yl) benzoic acid (Fluorescein 27) (F27) and N-[6-diethylamino)-9-(2,4-disulfophenyl)-3H-xanthen-3-ylidene]-N-ethylhydroxid (Sulfarhodamine B) (SRB) have been studied comprehensively in polar protic and polar aprotic solvents at room temperature (298 K). The bathochromic shift observed in absorption and fluorescence spectra of F27 and SRB with increasing solvent polarity signifies that the transition involved are π→π*. Solvatochromic correlations were used to obtain the ground and excited state dipole moments. The observed excited state dipole moments are found to be larger than their ground state counterparts in all the solvents studied. The ground and excited state dipole moments of these probes have also been computed from ab initio calculations and compared with those determined experimentally. Further, the experimentally obtained changes in dipole moment (Δμ) were compared with those using normalized polarity terms  from Reichardt equation.

The First to be Destroyed

The Jewish community of the city of Kleczew came into existence in the sixteenth century. It remained large and strong throughout the next four hundred years, and in the eighteenth and nineteenth centuries it constituted 40-60% of the total population. The German army entered Kleczew on September 15, 1939, shortly after the outbreak of World War II. The communities of Kleczew and the vicinity were among the first Jewish collectives in Europe to be totally destroyed. The events presented in this book reveal that the organization of deportations and the methods of mass murder conducted in this district, by Kommando Lange, served as a model that would be applied later in the death camps during the mass extermination of Polish and European Jewry. If so, it was in the woods near Kleczew that the “Final Solution of the Jewish Question” began

Żydzi na Kujawach w latach 1914-1922. Ujęcie porównawcze

Kujawy from 1815 to 1918/1920 was within the borders of Russia (eastern Kujawy) and Prussia (western Kujawy). In both parts, Jewish communities were established that were demographically, culturally, politically and religiously different, the so-called German Jews and Eastern Jews (Ostjuden). After World War I, Kujawy found itself in reborn Poland. The Jews living there had to adapt to the new conditions and confront new challenges such as migration movements, democratization of life, integration and disintegration of individual Jewish communities, the spontaneous development of social, political and cultural life in the eastern part of Kujawy and their regression in the western part. The background was the national and religious changes and the anti-Semitism that was intensifying in the first years of independent Poland

The First to be Destroyed

The Jewish community of the city of Kleczew came into existence in the sixteenth century. It remained large and strong throughout the next four hundred years, and in the eighteenth and nineteenth centuries it constituted 40-60% of the total population. The German army entered Kleczew on September 15, 1939, shortly after the outbreak of World War II. The communities of Kleczew and the vicinity were among the first Jewish collectives in Europe to be totally destroyed. The events presented in this book reveal that the organization of deportations and the methods of mass murder conducted in this district, by Kommando Lange, served as a model that would be applied later in the death camps during the mass extermination of Polish and European Jewry. If so, it was in the woods near Kleczew that the “Final Solution of the Jewish Question” began