Browsing by Author "Lloyd, Julian A."

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Citation - WoS: 16
Dynamics of Spatially Confined Bisphenol a Trimers in a Unimolecular Network on Ag(111)
(Amer Chemical Soc, 2016) Lloyd, Julian A.; Papageorgiou, Anthoula C.; Fischer, Sybille; Oh, Seung Cheol; Saglam, Ozge; Diller, Katharina; Duncan, David A.
Bisphenol A (BPA) aggregates on Ag(111) shows a polymorphism between two supramolecular motifs leading to formation of distinct networks depending on thermal energy. With rising temperature a dimeric pairing scheme reversibly converts into a trimeric motif, which forms a hexagonal superstructure with complex dynamic characteristics. The trimeric arrangements notably organize spontaneously into a self-assembled one-component array with supramolecular BPA rotors embedded in a two-dimensional stator sublattice. By varying the temperature, the speed of the rotors can be controlled as monitored by direct visualization. A combination of scanning tunneling microscopy and dispersion corrected density-functional tight-binding (DFTB-vdW(surf)) based molecular modeling reveals the exact atomistic position of each molecule within the assembly as well as the driving force for the formation of the supramolecular rotors.
Citation - WoS: 11
Citation - Scopus: 11
Isomerism Control of Diethylstilbestrol by Metal Surface Induced O-H Cleavage
(Royal Soc Chemistry, 2018) Oh, Seung Cheol; Lloyd, Julian A.; Fischer, Sybille; Saglam, OEzge; Papageorgiou, Anthoula C.; Diller, Katharina; Duncan, David A.
Diethylstilbestrol (DES) is studied on Ag(111) and Cu(111) surfaces using X-ray photoelectron spectroscopy (XPS) and scanning tunnelling microscopy (STM). We find that DES molecules on the silver surface adsorb intact and adopt a trans-conformation. On the more reactive copper surface, O-H bond cleavage results in molecular adsorption in the cis-conformation, thus providing the means of obtaining different adsorption geometries. The difference in isomerism is reflected in the observed self-assemblies which exhibit room-temperature stability.