A study of substituent effects on hydrogen-to-arene nonbonded interactions
摘要:
The polycylic aromatic hydrocarbon 9,14-diphenylbenzo[b]triphenylene is strongly twisted due to nonbonded interactions between hydrogen atoms on the polycyclic nucleus and the pi systems of the phenyl groups. Ten derivatives of 9,14-diphenylbenzo[b]triphenylene, with a wide variety of substituents on the phenyl groups, were synthesized and crystallographically characterized in order to test for the presence of electronic substituent effects on the magnitude of these hydrogen-to-arene nonbonded repulsions. The observed end-to-end twists in these compounds were the following: 9,14-diphenylbenzo[b]triphenylene (3) 40.4 +/- 0.4-degrees; 9,14-bis(4-nitrophenyl)-bezo[b]triphenylene (4), adopted a nontwisted conformation; 9,14-bis(4-methoxyphenyl)benzo[b]triphenylene (5), 36.8 +/- 1.3-degrees;9,14-bis[4-(methylthio)phenyl]benzo[b]triphenylene (6), 40.5+/-0.6-degrees;9,14-bis(4-chlorophenyl)-benzo[b]triphenylene (7), 39.4 +/- 0.5-degrees; 9,14-bromophenyl)benzo[b]triphenylene (8), 39.4+/-0.8-degrees;9,14-bis[4-(trifluoromethyl)phenyl]benzo[b]triphenylene (9), 36.3+/-1.5-degrees and 33.0 +/- 1.5-degrees (two crystallographically independent molecules); 9,14-bis(4-cyanophenyl)benzo[b]triphenylene (10), 38.2+/-0.5-degrees; 9,14-bis(4-methyl-phenyl)benzo[b]triphenylene (11), 43.1 +/- 0.4-degrees; 9,14-bis(4-nitrophenyl)-11-methylbenzo[b]triphenylene (12), 40.4 +/- 0.9-degrees and 33.4+/-0.9-degrees (two crystallographically independent molecules). The effects of the substituents and of crystal packing forces on the solid-state conformations of these compounds are discussed.
Tuning the Singlet-Triplet Gap in Metal-Free Phosphorescent π-Conjugated Polymers
作者:Debangshu Chaudhuri、Henning Wettach、Kipp J. van Schooten、Su Liu、Eva Sigmund、Sigurd Höger、John M. Lupton
DOI:10.1002/anie.201003291
日期:2010.10.11
Glow in the dark: A tunable singlet–triplet exchange gap arises in optically active conjugated polymers that exhibit both strong fluorescence from the singlet state and pronounced phosphorescence from triplet excitations (see picture). The polymers were incorporated into organic light‐emitting diodes (OLEDs).
Spatially Controlled Surface Immobilization of Nonmodified Peptides
作者:Thomas Pauloehrl、Alexander Welle、Michael Bruns、Katharina Linkert、Hans G. Börner、Martin Bastmeyer、Guillaume Delaittre、Christopher Barner-Kowollik
DOI:10.1002/anie.201302040
日期:2013.9.9
A phencyclone derivative is used to achieve light‐controlledimmobilization of peptides possessing only natural amino acids. The photoactive precursor (blue in picture) is formed in a Diels–Alder reaction and can undergo light‐triggered ring‐opening reactions with amines. Successful surface patterning with a genuine c(RGDfK) peptide (green) is evidenced by imaging time‐of‐flight secondary‐ion mass