0000000001306109
AUTHOR
Alfonso Zoleo
Electron Paramagnetic Resonance and petrographic analysis for dating Mesolithic and Neolithic pottery from Al Khiday (Sudan)
Abstract Electron Paramagnetic Resonance (EPR) dating, like luminescence techniques, is based on the time-dependent accumulation of trapped charges at mineral defect centres. However, Fe(III) ions prevent the common Continuous Wave (CW-EPR) approach for dating pottery, which always contains iron. The Pulsed method (ED-EPR) allowed this limitation to be overcome, with recording of radiation-induced defect signals, as shown by increased signal intensity after artificial irradiation of samples. The method was applied to studying Mesolithic and Neolithic pottery from Al Khiday (Central Sudan), characterized by quartz-rich tempers and coming from dated contexts. As the occurrence of a natural ED…
Au25(SEt)18 a nearly naked thiolate-protected Au25 cluster Struct. analysis by single crystal X-ray crystallograp. and electron nuclear double res
X-ray crystallography has been fundamental in discovering fine structural features of ultrasmall gold clusters capped by thiolated ligands. For still unknown structures, however, new tools capable of providing relevant structural information are sought. We prepared a 25-gold atom nanocluster protected by the smallest ligand ever used, ethanethiol. This cluster displays the electrochemistry, mass spectrometry, and UV-vis absorption spectroscopy features of similar Au25 clusters protected by 18 thiolated ligands. The anionic and the neutral form of Au25(SEt)18 were fully characterized by (1)H and (13)C NMR spectroscopy, which confirmed the monolayer's properties and the paramagnetism of neutr…
A magnetic look into the protecting layer of Au25 clusters
The field of molecular metal clusters protected by organothiolates is experiencing a very rapid growth. So far, however, a clear understanding of the fine interactions between the cluster core and the capping monolayer has remained elusive, despite the importance of the latter in interfacing the former to the surrounding medium. Here, we describe a very sensitive methodology that enables comprehensive assessment of these interactions. Pulse electron nuclear double resonance (ENDOR) was employed to study the interaction of the unpaired electron with the protons of the alkanethiolate ligands in four structurally related paramagnetic Au25(SR)0 18 clusters (R ¼ ethyl, propyl, butyl, 2-methylpro…
Gold Nanowired: A Linear (Au25)n Polymer from Au25 Molecular Clusters
Au25(SR)18 has provided fundamental insights into the properties of clusters protected by monolayers of thiolated ligands (SR). Because of its ultrasmall core, 1 nm, Au25(SR)18 displays molecular behavior. We prepared a Au25 cluster capped by n-butanethiolates (SBu), obtained its structure by single-crystal X-ray crystallography, and studied its properties both experimentally and theoretically. Whereas in solution Au25(SBu)18(0) is a paramagnetic molecule, in the crystal it becomes a linear polymer of Au25 clusters connected via single Au-Au bonds and stabilized by proper orientation of clusters and interdigitation of ligands. At low temperature, [Au25(SBu)18(0)]n has a nonmagnetic ground s…
CCDC 984217: Experimental Crystal Structure Determination
Related Article: Tiziano Dainese, Sabrina Antonello, José A. Gascón, Fangfang Pan, Neranjan V. Perera, Marco Ruzzi, Alfonso Venzo, Alfonso Zoleo, Kari Rissanen, and Flavio Maran|2014|ACS Nano|8|3904|doi:10.1021/nn500805n
CCDC 998586: Experimental Crystal Structure Determination
Related Article: Marco De Nardi, Sabrina Antonello, De-en Jiang, Fangfang Pan, Kari Rissanen, Marco Ruzzi, Alfonso Venzo, Alfonso Zoleo, Flavio Maran|2014|ACS Nano|8|8505|doi:10.1021/nn5031143
CCDC 1453036: Experimental Crystal Structure Determination
Related Article: Mikhail Agrachev, Sabrina Antonello, Tiziano Dainese, José A. Gascón, Fangfang Pan, Kari Rissanen, Marco Ruzzi, Alfonso Venzo, Alfonso Zoleo, Flavio Maran|2016|Chemical Science|7|6910|doi:10.1039/C6SC03691K
CCDC 1427512: Experimental Crystal Structure Determination
Related Article: Tiziano Dainese, Sabrina Antonello, José A. Gascón, Fangfang Pan, Neranjan V. Perera, Marco Ruzzi, Alfonso Venzo, Alfonso Zoleo, Kari Rissanen, and Flavio Maran|2014|ACS Nano|8|3904|doi:10.1021/nn500805n