**Acknowledgements**

The Coimbra Chemistry Centre is supported by the Fundação para a Ciência e a Tecnologia (FCT), Portuguese Agency for Scientific Research, through the Projects PEst-OE/QUI/ UI0313/2014 and POCI-01-0145-FEDER-007630. Sandra M.A. Cruz thanks the postdoc grant from Coimbra Chemistry Centre (Contract DPDRH-56-15-401). Tânia F.G.G. Cova also acknowledge the PhD research Grant SFRH/BD/95459/2013 assigned by FCT.
