English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Irrespective of the dielectric constant (epsilon) or the hydrogen-bonding ability of a pure solvent, the lowest excited singlet state (DBA*) of 9,10-dibromoanthracene (DBA) is quenched by ground-state 2,5-dimethylhexa-2,4-diene (DMHD) giving rise to the appearance of an exciplex emission. By means of sub-picosecond and nanosecond laser photolysis as well as steady-state photolysis, however, the following solvent-dependent results are obtained; (1) in acetonitrile (epsilon = 37.5) and acetone (epsilon = 20.7), an exciplex (DBA-DMHD)* formed between DBA* and DMHD generates the DBA radical anion (DBA(.-)) as an intermediate for formation of 9-bromoanthracene (BA) from DBA; (2) in ethanol (epsilon = 24.6), a-propanol (epsilon = 19.9), l-octanol (epsilon = 10.3), diethyl ether (epsilon = 4.34), and heptane (epsilon = 1.92),, a neutral radical species (NR) generated by decomposition of (DBA-DMHD)* (or by a reaction of DBA* with DMHD) is an intermediate for formation of a dibenzobicyclo[2.2.2]octadiene-type compound (a [4+2] adduct); (3) both DBA(.-) and NR. are generated in methanol (epsilon = 32.7) but the rate (upsilon) of BA formation upon steady-state photolysis of DBA in the presence of 1 M DMHD decreases in the order of upsilon(acetonitrile, epsilon = 37.5) > upsilon(acetone, epsilon = 20.7) > upsilon(methanol, epsilon = 32.7). It thus can be concluded that the mechanism of exciplex decomposition and the reaction of DBA* with DMHD are affected by not only the dielectric constant of a pure solvent but also its hydrogen-bonding ability.

acta physica polonica. a

Solvent-Dependent Quenching of the Lowest Excited Singlet State of 9,10-Dibromoanthracene by Ground-State 2,5-Dimethylhexa-2,4-Diene Yielding 9-Bromoanthracene or the [4+2] Adduct