Contributed Speaker
Letizia Savio
Self-organization of Pd-cyclometalated compounds on HOPG
Ola Alayan1,2, Giovanni Carraro2, Marco Smerieri2, Luca Vattuone1,2, Mario Agostino
Rocca1,2, Martina dell’Angela3, Roberto Costantini3, Albano Cossaro3,4, Gianangelo Bracco1,2, Letizia Savio2
¹ DIFI, UniGe, Via Dodecaneso 33, 16146 Genova, Italy
² IMEM-CNR, UOS Genova, Via Dodecaneso 33, 16146 Genova, Italy
3CNR-IOM, Strada Statale 14 – km 163.5, 34149 Trieste, Italy
4Dipartimento di Scienze Chimiche e Farmaceutiche, UniTs, via L. Giorgieri 1, 34127 Trieste, Italy
Organometallic complexes containing Ni, Pt or Pd atoms are interesting mainly for their polyvalent applications in different fields, spanning from catalysis [1], to biochemistry [2] and materials science [3]. Pd-containing compounds have been broadly studied as catalysts and nowadays, the synthesis of Pd containing molecules with engineered properties is possible. Despite these compounds participate in various surface processes, their interaction with surfaces remains largely unexplored.
We studied the interaction of different Pd-cyclometallated compounds (CyPd) with Ag (110), finding that the substrate was too reactive to allow for the formation of an ordered C-based network with Pd atoms acting as active sites [4-6]. Therefore, we moved to the less interactive highly oriented pyrolytic graphite (HOPG): three different CyPd complexes were deposited on freshly cleaved HOPG either by sublimation from a crucible under UHV conditions or by drop-casting from a DMF solution. The systems were comparatively studied by X-ray photoelectron spectroscopy (XPS - ALOISA beamline of the Elettra Synchrotron radiation source) to determine the chemistry and thermal evolution of the self-assembled layers, while the morphology at the mesoscale of drop-casted samples was investigated by non-contact atomic force microscopy (nc-AFM - model NX10 by Park Systems).
We found that all the molecular complexes adsorb intact and that, when deposited by drop-casting, they arrange on the surface forming islands of few mm in size and with highly corrugated edges. Upon mild annealing, the islands get more compact. When the temperature is increased further a different thermal evolution sets in competing with desorption for the three different compounds and leads eventually to the appearance of neutral Pd adatoms (Pd(0)) above a critical temperature.
References
[1] H. Chen, Y. Li, S. Liu, Q. Xiong, R. Bai, D. Wei, Y. Lan., Coord. Chem. Rev. 437 (2021) 213863.
[2] M. Mauro, A. Aliprandi, D. Septiadi, N. S.Kehr, L. De Cola., Chem. Soc. Rev. 43 (2014) 4144.
[3] V. W. W. Yam, V. K. M. Au, S. Y. L. Leung., Chem. Rev. 115 (2015) 7589.
[4]M. Stojkovska, et al., Appl. Surf. Sci. 606 (2022) 154960.
[5] J. E. Barcelon, et al., Appl. Surf. Sci. 609 (2023) 155307.
[6] M. Stojkovska, et al., submitted for publication