Probing Peripheral H-Bonding Functionalities in BN-Doped Polycyclic Aromatic Hydrocarbons.

The replacement of carbon atoms at the zigzag periphery of a benzo[]tetracenyl derivative with an NBN atomic triad allows the formation of heteroatom-doped polycyclic aromatic hydrocarbon (PAH) isosteres, which expose BN mimics of the amidic N functions. Their ability to form H-bonded complexes has never been touched so far. Herein, we report the first solution recognition studies of peripherally NBN-doped PAHs to form H-bonded DD·AA- and ADDA·DAAD-type complexes with suitable complementary H-bonding acceptor partners.

Toward Fractioning of Isomers through Binding-Induced Acceleration of Azobenzene Switching.

The E/Z isomerization process of a uracil-azobenzene derivative in which the nucleobase is conjugated to a phenyldiazene tail is studied in view of its ability to form triply H-bonded complexes with a suitably complementary 2,6-diacetylamino-4-pyridine ligand. UV-vis and H NMR investigations of the photochemical and thermal isomerization kinetics show that the thermal Z → E interconversion is 4-fold accelerated upon formation of the H-bonded complex. DFT calculations show that the formation of triple H-bonds triggers a significant elongation of the N═N double bond, caused by an increase of its π* antibonding character.

Trapping of Charged Gold Adatoms by Dimethyl Sulfoxide on a Gold Surface.

We report the formation of dimethyl sulfoxide (DMSO) molecular complexes on Au(111) enabled by native gold adatoms unusually linking the molecules via a bonding of ionic nature, yielding a mutual stabilization between molecules and adatom(s). DMSO is a widely used polar, aprotic solvent whose interaction with metal surfaces is not fully understood. By combining X-ray photoelectron spectroscopy, low temperature scanning tunneling microscopy, and density functional theory (DFT) calculations, we show that DMSO molecules form complexes made by up to four molecules arranged with adjacent oxygen terminations.