During the last decades, intensive efforts have been devoted to the synthesis of porphyrin assemblies, and many synthetic routes have been reported. One of the most promising synthetic route to obtain multi-porphyrin assemblies makes use of metal ions as connectors between porphyrins. The versatility of the coordination bonds in terms of geometry and stability is of interest to synthesize original multi-porphyrin assemblies in few synthetic steps compared to more tedious chemical transformations usually needed to link porphyrins with covalent bonds. However, the use of metal ions as connectors between porphyrins is most of the time not suitable in terms of interactions between individual porphyrins, especially when the coordination site is poorly conjugated with the aromatic core of the macrocycle. To overcome this issue, we designed several flat porphyrin building-blocks having external coordination sites fully conjugated with the aromatic core of the porphyrins. We will show (i) how these porphyrins were prepared,[1] (ii) how they can be used as building-blocks to synthesize discrete multi-porphyrin assemblies,[2] and (iii) which systems offer best opportunities to observe strong interactions between individual porphyrins through the assembling metal ions.[3]

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[1] a) Richeter, S.; Jeandon, C.; Gisselbrecht, J.-P.;  Ruppert, R.; Callot, H. J. J. Am. Chem. Soc. 2002, 124, 6168; b) Richeter, S.; Jeandon, C.; Gisselbrecht, J.-P.; Graff, R.; Ruppert, R.; Callot, H. J. Inorg. Chem. 2004, 43, 251; c) Richeter, S.; Jeandon, C.; Gisselbrecht, R.; Ruppert, R.; Callot, H. J. Inorg. Chem. 2007, 46, 10241; d) Lefebvre, J.-F.; Leclercq, D.; Gisselbrecht, J.-P.; Richeter, S. Eur. J. Org. Chem. 2010, 1912; e) Lo, M.; Lefebvre, J.-F.; Leclercq, D.; van der Lee, A.; Richeter, S. Orga. Lett. 2011, 13, 3110.

[2] a) Richeter, S.; Jeandon, C.; Ruppert, R.; Callot, H. J. Chem. Commun. 2002, 266; b) Callot, H. J.; Ruppert, R.; Jeandon, C.; Richeter, S. J. Porphyrins Phthalocyanines 2004, 8, 111; c) Richeter, S.;  Hadj-Aïssa, A.; Taffin, C.;  van der Lee, A.;  Leclercq, D. Chem. Commun. 2007, 2148.

[3] a) Abdelhameed, M. Karsenti, P.-L.; Langlois, A.; Lefebvre, J.-F.; Richeter, S.; Ruppert, R.; Harvey, P. D. Chem. Eur. J. 2014, 20, 12988; b) Abdelhameed, M. Karsenti, P.-L.; Richeter, S.; Ruppert, R.; Harvey, P. D. Chem. Eur. J. 2014, 20, 12988; b) Abdelhameed, M.; Langlois, A.; Karsenti, P.-L.; Richeter, S.; Ruppert, R.; Harvey, P. D. Chem. Commun. 2014, 50, 14609.