Engineering cofacial porphyrin dimers using lacunary polyoxotungstates

Abstract

Cofacial porphyrin dimers have garnered extensive attention for their unique photophysical and catalytic properties, which strongly depend on structural configurations. However, precisely controlling key parameters, such as lateral and rotational displacements, interfacial distance, and stability, remains challenging. Herein, we present a novel strategy for engineering porphyrin dimer structures and properties using multivacant lacunary polyoxometalates (POMs), [SiW₁₀O₃₆]⁸⁻ or [SiW₉O₃₄]¹⁰⁻, as linkers. By adjusting the types and coordination modes of lacunary POMs, three distinct hybrids were obtained via the self-assembly of two 5,10,15,20-tetra(4-pyridyl)porphyrin molecules and four lacunary POM units, each exhibiting modulated stacking geometries, interfacial distances and interactions, and photophysical properties. These hybrids demonstrated efficient visible-light-responsive photosensitized reactions to generate singlet oxygen from ground-state triplet oxygen (³O₂), leading to the photooxidation of various organic substrates. Notably, hybrid II, constructed using [SiW₁₀O₃₆]⁸⁻, exhibited the strongest π–π interactions, distinct optical properties, and enhanced resistance to -induced degradation. These findings highlight the potential of POMs as versatile tools for the precise control of porphyrin dimer architectures and the development of materials with tailored photophysical and catalytic functions.