12 research outputs found
PND16 ASSOCIATION OF LONG-TERM MIGRAINE PREVENTIVE MEDICATION USE AND RESOURCE UTILIZATION/PRODUCTIVITY LOSS: RESULTS FROM THE AMERICAN MIGRAINE PREVALENCE AND PREVENTION (AMPP) STUDY
Acylation and Esterification of the Aryloxide Ligand in [AIMe( dbmp),l. Crystal Structures of [Al Me( dbmp) - (bhmap)], Hbhmap and O=C(dbmp)But (Hdbmp = 2,6=di- tert-butyl-4-methylphenol, Hbhmap = 3-tert-butyl-2- hydroxy-5-methylacetophenone) t
13. The molecular structures of 1, 5 and 12 have been confirmed by Xray crystallography
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Using sulfur bridge oxidation to control electronic coupling and photochemistry in covalent anthracene dimers
Covalently tethered bichromophores provide an ideal proving ground to develop strategies for controlling excited state behavior in chromophore assemblies. In this work, optical spectroscopy and electronic structure theory are combined to demonstrate that the oxidation state of a sulfur linker between anthracene chromophores gives control over not only the photophysics but also the photochemistry of the molecules. Altering the oxidation state of the sulfur linker does not change the geometry between chromophores, allowing electronic effects between chromophores to be isolated. Previously, we showed that excitonic states in sulfur-bridged terthiophene dimers were modulated by electronic screening of the sulfur lone pairs, but that the sulfur orbitals were not directly involved in these states. In the bridged anthracene dimers that are the subject of the current paper, the atomic orbitals of the unoxidized S linker can actively mix with the anthracene molecular orbitals to form new electronic states with enhanced charge transfer character, different excitonic coupling, and rapid (sub-nanosecond) intersystem crossing that depends on solvent polarity. However, the fully oxidized SO2 bridge restores purely through-space electronic coupling between anthracene chromophores and inhibits intersystem crossing. Photoexcitation leads to either internal conversion on a sub-20 picosecond timescale, or to the creation of a long-lived emissive state that is the likely precursor of the intramolecular [4 + 4] photodimerization. These results illustrate how chemical modification of a single atom in the covalent bridge can dramatically alter not only the photophysics but also the photochemistry of moleculesThis work was supported by the Basque Government (IT588-13) and the Spanish Government MINECO/FEDER (CT2016-80955-P). C. C. is indebted to the European Research Council (ERC-2016-STG-714870) for a postdoctoral contract. M. O. W. acknowledges support from the Natural Sciences and Engineering Research Council. C. J. B. acknowledges support from the National Science Foundation grant CHE-180018
Examining the Predictive Validity of Gre Scores on Doctoral Education: Students' Success and Methodology Choices in the Dissertation Process
This study examines how GRE scores can be used to better understand Education doctoral candidates\u27 methodology choices for the dissertation as well as their persistence behaviors. Candidates\u27 of one online doctoral education program were examined. Results of a MANOVA suggested that there is no difference in GRE scores based on doctoral candidates\u27 choice of methodology. Although GRE scores did not differ based on methodology choice, results of the regression analysis indicated that the linear combination of candidates\u27 verbal reasoning scores, quantitative reasoning scores, writing scores, and methodology choices accounted for significant variability in the number of semesters it took for them to complete their dissertations. The GRE writing score and methodology choice were the strongest predictors of time to completion