Charge Delocalization and Global Aromaticity in a Partially Fused 12-Porphyrin Nanoring

07 March 2024, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Aromatic and antiaromatic ring currents can reveal global electronic delocalization around the circumference of pi-conjugated macrocycles, although these phenomena are poorly understood in large rings. Here we present the template-directed synthesis of a fully pi-conjugated cyclic porphyrin 12-mer consisting of six b,meso,b-edge-fused porphyrin dimers connected by six butadiyne bridges. The lowest energy pi-pi* absorption band of this partially fused nanoring is shifted far into the NIR, confirming the strong pi-conjugation around the circumference of the macrocycle. Investigation of the oxidized and reduced nanoring-template complex by 1H and 19F NMR spectroscopy demonstrates the presence of coherent global (anti)aromatic ring currents, consistent with DFT calculations. The stronger -conjugation enables global charge delocalization even at low levels of oxidation or reduction. These findings open new avenues for the engineering of cyclic molecular wires.


ring currents
nuclear magnetic resonance
host-guest complex
template-directed synthesis

Supplementary materials

Supplementary Information
Experimental details and supplementary data.


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