Supporting Information for: Oxygenic Polyoxometalates: a New Class of Molecular Propellers Andrea Sartorel,* a Melissa Truccolo, a Serena Berardi, a Martino Gardan, a Mauro Carraro, a Francesca Maria Toma, b Gianfranco Scorrano, a Maurizio Prato b and Marcella Bonchio* a Materials and Methods. Thermogravimetric Analysis (TGA): Thermogravimetric analyses were performed on a TGA Q500 (TA Instruments) and recorded under N 2 or under air, upon equilibration at 100 °C, followed by a ramp of 10 °C/min up to 1000 °C. Resonance Raman (rRaman): Micro-Raman spectra were recorded with a inVia Reflex Renishaw spectrometer equipped with three lasers (532, 632.8 and 785 nm). The laser beam was focused on an area of about 2x2 μm and with power lower than 1 mW. Analysis of O 2 content: An Ocean Optics oxygen sensor system (FOXY R-AF) was used for the quantitative detection of O 2 . The experiments were performed in a custom built reactor, closed with a special cap in which the sensor is inserted. The calibration was performed using a temperature sensor. UV-Vis: UV-Vis spectra were recorded using a Perkin-Elmer Lambda 45 spectrophotometer. Syntheses of transition metal substituted polyoxometalates. The synthesis of the polyoxometalates used in this work was performed as described in the literature. In particular: Ru 4 (SiW 10 ) 2 : A. Sartorel, M. Carraro, G. Scorrano, R. De Zorzi, S. Geremia, N. D. Mc Daniel, S. Bernhard and M. Bonchio, J. Am. Chem. Soc., 2008, 130, 5006. Cu 4 (PW 9 ) 2 : R. G. Finke, M. W. Droege and P. J. Domaille, Inorg. Chem., 1987, 26, 3886. Co 4 (PW 9 ) 2 : T. J. R. Weakley, H. T. Evans, J. S. Showell, G. F. Tourné and C. M. Tourné, J. Chem. Soc., Chem. Commun., 1973, 139; R. G. Finke, M. W. Droege and P. J. Domaille, Inorg. Chem., 1987, 26, 3886. Ni 4 (PW 9 ) 2 , J. M. Clemente-Juan, E. Coronado, J. R. Galán-Mascarós and C. J. Gómez-García, Inorg. Chem., 1999, 38, 55. Mn 4 (PW 9 ) 2 : C. J. Gómez-García, E. Coronado, P. Gómez-Romero and N. Casañ-Pastor, Inorg. Chem., 1993, 32, 3378. Supplementary Material (ESI) for Chemical Communications This journal is (c) The Royal Society of Chemistry 2011