University of Marburg

About: University of Marburg is a education organization based out in Marburg, Germany. It is known for research contribution in the topics: Population & Virus. The organization has 23195 authors who have published 42907 publications receiving 1506069 citations. The organization is also known as: Philipps University of Marburg & Philipps-Universität.

Asymmetric photoredox transition-metal catalysis activated by visible light

Abstract: Asymmetric catalysis is seen as one of the most economical strategies to satisfy the growing demand for enantiomerically pure small molecules in the fine chemical and pharmaceutical industries. And visible light has been recognized as an environmentally friendly and sustainable form of energy for triggering chemical transformations and catalytic chemical processes. For these reasons, visible-light-driven catalytic asymmetric chemistry is a subject of enormous current interest. Photoredox catalysis provides the opportunity to generate highly reactive radical ion intermediates with often unusual or unconventional reactivities under surprisingly mild reaction conditions. In such systems, photoactivated sensitizers initiate a single electron transfer from (or to) a closed-shell organic molecule to produce radical cations or radical anions whose reactivities are then exploited for interesting or unusual chemical transformations. However, the high reactivity of photoexcited substrates, intermediate radical ions or radicals, and the low activation barriers for follow-up reactions provide significant hurdles for the development of efficient catalytic photochemical processes that work under stereochemical control and provide chiral molecules in an asymmetric fashion. Here we report a highly efficient asymmetric catalyst that uses visible light for the necessary molecular activation, thereby combining asymmetric catalysis and photocatalysis. We show that a chiral iridium complex can serve as a sensitizer for photoredox catalysis and at the same time provide very effective asymmetric induction for the enantioselective alkylation of 2-acyl imidazoles. This new asymmetric photoredox catalyst, in which the metal centre simultaneously serves as the exclusive source of chirality, the catalytically active Lewis acid centre, and the photoredox centre, offers new opportunities for the 'green' synthesis of non-racemic chiral molecules.

The utility of a broader conceptualization of organizational identification: Which aspects really matter?

Abstract: Predictions of social identity and self-categorization theories about the relevance of social identification in organizational contexts are presented We propose that different foci of identification (eg with own career, team, organization, occupation) as well as different dimensions of organizational identification (cognitive, affective, evaluative, and behavioural) can be separated Furthermore, these different aspects of organizational identification are assumed to be differentially associated with work-related attitudes and behaviours Predictions are first tested in a questionnaire study of 515 German school teachers Confirmatory factor analyses demonstrated that dimensions and foci can indeed be differentiated In addition, results indicate that different aspects correlate differentially with different criteria The results are cross-validated in two samples of 233 German school teachers and 358 bank accountants, respectively

Factors that impact on quality of life in Parkinson's disease: results from an international survey

Abstract: Current management guidelines for the treatment of patients with Parkinson's disease (PD) are limited due to the lack of knowledge of factors that influence health‐related quality of life (HRQL). To assess the HRQL of people with PD, and to systematically identify and evaluate those factors (other than disease severity and medication, which could have an impact), we undertook a cross‐sectional, randomized selection, multicenter international survey of patients with PD, caregivers, and clinicians. Face‐to‐face interviews were conducted with subjects in six countries. Disease severity, medication, and other factors hypothesized to influence HRQL were assessed using a combination of specially developed questionnaires and validated instruments including the Parkinson's Disease Questionnaire‐39 (HRQL), Hoehn and Yahr Stage (disease severity), and Beck's Depression Inventory (BDI; depression). Multiple linear regression models were used to demonstrate whether the factors investigated contribute significantly to HRQL. The results obtained indicated that Hoehn and Yahr stage and medication explained only 17.3% of the variability in HRQL of patients with PD, although both were significant (R2 = 0.173, P < 0.05). Other factors increased the explanatory power to adjusted R2 = 0.597, with BDI being the most significant predictor of variability in HRQL (adjusted R2 = 0.582; P < 0.001), followed by “Satisfaction with the explanation of the condition at diagnosis” and “Current feelings of optimism” (both P < 0.05). These factors, in addition to disease severity and medication, explain 59.7% of the variability in HRQL across the population. In conclusion, depression (as measured by the BDI) in PD, “satisfaction with the explanation of the condition at diagnosis” and “current feelings of optimism” have a significant impact on HRQL. The completion of this initial analysis is the first step towards developing management guidelines that truly influence the HRQL of patients with PD. © 2001 Movement Disorder Society.