TY  - JOUR
A1  - Rauch, Florian
A1  - Endres, Peter
A1  - Friedrich, Alexandra
A1  - Sieh, Daniel
A1  - Hähnel, Martin
A1  - Krummenacher, Ivo
A1  - Braunschweig, Holger
A1  - Finze, Maik
A1  - Ji, Lei
A1  - Marder, Todd B.
T1  - An Iterative Divergent Approach to Conjugated Starburst Borane Dendrimers
JF  - Chemistry – A European Journal
N2  - Using a new divergent approach, conjugated triarylborane dendrimers were synthesized up to the 2nd generation. The synthetic strategy consists of three steps: 1) functionalization, via iridium catalyzed C−H borylation; 2) activation, via fluorination of the generated boronate ester with K[HF\(_{2}\)] or [N(nBu\(_{4}\))][HF\(_{2}\)]; and 3) expansion, via reaction of the trifluoroborate salts with aryl Grignard reagents. The concept was also shown to be viable for a convergent approach. All but one of the conjugated borane dendrimers exhibit multiple, distinct and reversible reduction potentials, making them potentially interesting materials for applications in molecular accumulators. Based on their photophysical properties, the 1st generation dendrimers exhibit good conjugation over the whole system. However, the conjugation does not increase further upon expansion to the 2nd generation, but the molar extinction coefficients increase linearly with the number of triarylborane subunits, suggesting a potential application as photonic antennas.
KW  - density functional calculations
KW  - electron storage
KW  - luminescence
KW  - redox
KW  - triarylborane
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-218345
VL  - 26
IS  - 57
SP  - 12951
EP  - 12963
ER  - 
TY  - JOUR
A1  - Merz, Julia
A1  - Dietz, Maximilian
A1  - Vonhausen, Yvonne
A1  - Wöber, Frederik
A1  - Friedrich, Alexandra
A1  - Sieh, Daniel
A1  - Krummenacher, Ivo
A1  - Braunschweig, Holger
A1  - Moos, Michael
A1  - Holzapfel, Marco
A1  - Lambert, Christoph
A1  - Marder, Todd  B.
T1  - Synthesis, Photophysical and Electronic Properties of New Red-to-NIR Emitting Donor-Acceptor Pyrene Derivatives
JF  - Chemistry - A European Journal
N2  - We synthesized new pyrene derivatives with strong bis(para ‐methoxyphenyl)amine donors at the 2,7‐positions and n ‐azaacene acceptors at the K‐region of pyrene. The compounds possess a strong intramolecular charge transfer, leading to unusual properties such as emission in the red to NIR region (700 nm), which has not been reported before for monomeric pyrenes. Detailed photophysical studies reveal very long intrinsic lifetimes of >100 ns for the new compounds, which is typical for 2,7‐substituted pyrenes but not for K‐region substituted pyrenes. The incorporation of strong donors and acceptors leads to very low reduction and oxidation potentials, and spectroelectrochemical studies show that the compounds are on the borderline between localized Robin‐Day class‐II and delocalized Robin‐Day class‐III species.
KW  - orylation
KW  - K-region
KW  - luminescence
KW  - polycyclic aromatic hydrocarbons
KW  - redox
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-207486
VL  - 26
IS  - 2
ER  -