INSTITUTO DE QUIMICA, FISICA DE LOS MATERIALES, MEDIOAMBIENTE Y ENERGIA
Unidad Ejecutora - UE
Self-Assembled monolayers of disulphide Cu porphyrins on Au surfaces: adsorption induced reduction and demetalation
M. V. RIVAS; L. P. MENDEZ DE LEO; M. HAMMER; R. CARBALLO; F. J. WILLIAMS
AMER CHEMICAL SOC
Año: 2011 vol. 27 p. 10714 - 10714
Metalloporphyrinmolecules have a wide range of potential applications in diverse technological areas ranging from electronics to optoelectronics, electrochemistry, photophysics, chemical sensors, and catalysis. In particular, selfassembled monolayers of porphyrin molecules have recently attracted considerable interest. In this work we have studied for the first time the self-assembly of a novel Cu deutero porphyrin functionalized with disulfide moieties using electrochemical techniques, UVvis absorption spectroscopy, polarization modulation infrared reflection absorption spectroscopy, and photoelectron spectroscopies (XPS and UPS). Experimental results indicate that the molecule adsorbs retaining its molecular integrity without forming molecular aggregates via the formation of AuS covalent bonds. Furthermore, the monolayer consists of a packed array of molecules adsorbed with the plane of the porphyrin molecule at an angle of around 30 with respect to the surface normal. Interestingly, adsorption induces reduction of the Cu center and its consequent removal from the center of the porphyrin ring resulting in porphyrin demetalation. Our results are important in the design of self-assembled monolayers of metallo porphyrins where not only blocking of the metal center by the functional groups that drive the self-assembly should be considered but also possible adsorption induced demetalation with the consequent loss in the properties imparted by the metal center.