Effects of removing boron from subphthalocyanines: a theoretical perspective

The element hosted within the inner cavity of phthalocyanines (Pcs) dictates the wide functional versatility of these well-known macrocycles. Subphthalocyanines (SubPcs), by contrast, are only known as boron complexes, yet they exhibit a range of emerging properties unattainable with other compounds. The effects of replacing the boron atom in these macrocycles, however, remain unclear. Herein, we present a comprehensive theoretical investigation of non-boron SubPc complexes incorporating various metal and non-metal elements. Specifically, we use density functional theory (DFT) to assess the impact of boron replacement on bowl depth, dipole moment, charge distribution, key frontier molecular orbitals, UV-vis absorption properties, ionization potential, and electron affinity of SubPcs. Our findings reveal that substituting the boron atom induces significant alterations across these properties, with pronounced variability depending on the group, atomic size, and oxidation state of the central element. Altogether, this study underscores the functional versatility that non-boron SubPcs could introduce within the broader field of porphyrinoid chemistry, paving the way for disruptive materials with tailored electronic and photophysical properties.