transition metal complexes; electron transfer; dyads; artificial photosynthesis; Quantum Dots
LucariniFiorella, RuggiAlbert (2018), Heptacoordinate Co(II) Catalyst for Light-driven Hydrogen Production in Fully Aqueous Medium, in Chimia
, 72(4), 203-206.
Lucarini Fiorella, Pastore Mariachiara, Vasylevskyi Serhii, Varisco Massimo, Solari Euro, Crochet Aurelien, Fromm Katharina M., Zobi Fabio, Albert Ruggi (2017), Heptacoordinate CoII Complex: A New Architecture for Photochemical Hydrogen Production, in Chemistry-A European Journal
, 23(28), 6768-6771.
The development of technologies aimed to produce fuels from widely available sources in an economic and sustainable way is one of the most important scientific challenges of XXI century, considering the economical impact of the current raise of energy demand and the environmental effects deriving from the massive use of fossil fuels. Amongst the traditional strategies currently used to produce green energy from renewable sources, the possibility of obtaining a highly energetic and environmental friendly fuel like hydrogen using sunlight and water as starting sources would have an enormous impact on the everyday life. A system capable of realising water splitting by using sunlight has been the “Holy Grail” of scientific research for at least three decades. Semiconductor Quantum Dots have recently been object of a growing attention for application in solar cells and optoelectronic devices, due to their bright performances in terms of light absorption and photostability. However, only a very few system based on Quantum Dots have been reported so far in the field of artificial photosynthesis and in most cases such systems have been only poorly characterised in terms of electron transfer dynamics. Here we propose a new approach based on a family of dyads and triads containing a semiconductor Quantum Dot as sensitizer and transition metals-based catalysts. The objectives of this proposal can be summarized as follows:1) Synthesis of dyads containing oxidising moieties based on Ir(III) and Fe(II) complexes functionalised with spacers of different length and chemical nature and with a dithiocarbamate connecting unit. 2) Synthesis of dyads containing reducing moieties based on Co(III) and Co(II) complexes functionalised with spacers of different length and chemical nature and with a dithiocarbamate connecting unit.3) Synthesis of triads containing oxidation and reducing moieties connected to a rigid scaffold. 4) In-depth study of the photophysical properties of such dyads and triads, with special attention to the electron/hole transfer dynamics taking place between the Quantum Dot (sensitizer) and the metal complexes (photocatalysts) aimed at the realization of an optimised integrated system for water splitting.Compared to the systems so far realized in this field, our strategy shows several advantages: • Semiconductor Quantum Dots show high photostability (in the presence of suitable capping units) and high molar extinction coefficients, thus they are ideal light harvesting units.• Transition metal complexes can be attached to the Quantum Dots surface by dithiocarbamate functional groups, which can be easily prepared starting from primary amines. • The modularity of the system enables to optimise separately the two catalytic moieties.• The study of the electron transfer mechanisms in dyads will enable us to develop a strategy to avoid back-electron transfer upon induction of a kinetic-controlled unidirectional electron transfer in triads. We argue that the research presented in this proposal represents a major step towards the definition of a straightforward method for the realization of integrated systems (triads) for light-driven water splitting. Besides the evident impact of such systems on the everyday life, the in-depth investigation of the photoinduced electron transfer process is expected to give a remarkable contribution to the photochemical research in the field of artificial photosynthesis.