Control of Porphyrin Planarity and Aggregation by Covalent Capping: Bissilyloxy Porphyrin Silanes

Burhan A. Hussein, Zainab Shakeel, Andrew T. Turley, Aisha N. Bismillah, Kody M. Wolfstadt, Julia E. Pia, Melanie Pilkington, Paul R. McGonigal, Marc J. Adler*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Porphyrins are cornerstone functional materials that are useful in a wide variety of settings, ranging from molecular electronics to biology and medicine. Their applications are often hindered, however, by poor solubilities that result from their extended, solvophobic aromatic surfaces. Attempts to counteract this problem by functionalizing their peripheries have been met with only limited success. Here, we demonstrate a versatile strategy to tune the physical and electronic properties of porphyrins using an axial functionalization approach. Porphyrin silanes (PorSils) and bissilyloxy PorSils (SOPS) are prepared from porphyrins by operationally simple κ4N-silylation protocols, introducing bulky silyloxy "caps"that are central and perpendicular to the planar porphyrin. While porphyrins typically form either J-or H-aggregates, SOPS do not self-associate in the same manner: The silyloxy axial substituents dramatically improve the solubility by inhibiting aggregation. Moreover, axial porphyrin functionalization offers convenient handles through which optical, electronic, and structural properties of the porphyrin core can be modulated. We observe that the identity of the silyloxy substituent impacts the degree of planarity of the porphyrin in the solid state as well as the redox potentials.

Original languageEnglish
Pages (from-to)13533-13541
Number of pages9
JournalInorganic Chemistry
Issue number18
Early online date30 Aug 2020
Publication statusPublished - 21 Sept 2020

Bibliographical note

Funding Information:
The authors would like to thank Ryerson University for funding. B.A.H. acknowledges the Engineering and Physical Sciences Research Council (EPSRC) Centre for Doctoral Training in Soft Matter and Functional Interfaces (SOFI) for a PhD studentship. A.T.T. and A.N.B. acknowledge EPSRC Doctoral Training Grants. M.P. acknowledges NSERC RTI for support. The authors also thank Bryan Koivisto and Stefania Impellizzeri (Ryerson University) for advice and support.

Publisher Copyright:
© 2020 American Chemical Society.

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