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Senge_PicketFencePor.pdf (2.38 MB)

Strategic Synthesis of ‘Picket Fence’ Porphyrins Based on Nonplanar Macrocycles

submitted on 23.01.2021, 16:39 and posted on 25.01.2021, 12:19 by Karolis Norvaisa, Kathryn Yeow, Brendan Twamley, Marie Roucan, Mathias O.. Senge
Traditional ‘picket fence’ porphyrin systems have been a topic of interest for their capacity to direct steric shielding effects selectively to one side of the macrocycle. Sterically overcrowded porphyrin systems that adopt macrocycle deformations have recently drawn attention for their applications in organocatalysis and sensing. Here we explore the combined benefits of nonplanar porphyrins and the old molecular design to bring new concepts to the playing field. The challenging ortho-positions of meso-phenyl residues dodecasubstituted porphyrin systems led us to transition to less hindered para- and meta-sites and develop selective demethylation based on the steric interplay. Isolation of the symmetrical target compound [2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetrakis(3,5-dipivaloyloxyphenyl)porphyrin] was investigated under two synthetic pathways. The obtained insight was used to isolate unsymmetrical [2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetrakis(2-nitro-5-pivaloyloxyphenyl)porphyrin]. Upon separation of the atropisomers, a detailed single-crystal X-ray crystallographic analysis highlighted intrinsic intermolecular interactions. The nonplanarity of these systems in combination with ‘picket fence’ motifs provides an important feature in the design of supramolecular ensembles.


Science Foundation Ireland (IvP 13/IA/1894)

Irish Research Council (GOIPG 2017/1172)

Technical University of Munich – Institute for Advanced Studies (Hans Fischer Senior Fellowship)

European Union’s Horizon 2020 research and innovation program (FET Open grant agreement No. 828779)


Email Address of Submitting Author


Trinity College Dublin, the University of Dublin



ORCID For Submitting Author


Declaration of Conflict of Interest

The authors declare no conflict of interest.

Version Notes

Version 1.0