6.1 Future work

Through the course of this work, different molecules have been examined separately on several surfaces. This has been beneficial in understanding their individual behaviours, however the next step seems clear, to take this information and combine the molecules on the same surface.

Taking the dechlorinated Mn(III)TPP/Ag(111) system as the starting point, fullerenes can act as ligands in organometallic chemistry, and their size is comparable with that of the TPP molecule, so it is possible that the C60 may ligate to the undercoordinated Mn(III) centre. This would be an interesting result, as C60 has been shown to form a 1:1 mixture with octaethyl-porphyrins, but to completely replace the first layer of TPP on Ag(110) [230, 231].

Control over the orientation of a C60 molecule adsorbed on top of a CeTPP dyad has been shown using STM, with large changes in the conductance depending on the C60 orientation [232]. If the C60 was more strongly bound to the porphyrin however, as in the case of C60 ligating to MnTPP, it may not be possible to switch its orientation using the STM tip, but their relative orientation may determine charge injection through the system, and so it may be possible to distinguish between C60 orientations by their apparent height in STM even at room temperature.

On the Ag(111) surface, the number and size of substituent groups has been shown to determine the ordering of fullerene/porphyrin adlayers [8], and so it may be interesting to compare the small, linear NiDPP molecules’ effect on the co-adsorption with the square MnClTPP molecules.

Another interesting avenue of exploration would be to test the effect of other gases on the Mn(III)TPP/Ag(111) system. If the central Mn(III) ion could be shown to bind selectively to other oxygen-containing gases such as CO, CO2 or the oxides of nitrogen: combustion by-product NO; greenhouse gas N2O; or pollutant and toxin NO2; the molecule’s sensitivity and selectivity as a gas sensor could be examined, which could have prospects for future applications.