Computational Design\nof (B)Chl Models: Structural\nand Chemical Modifications toward Enriched Properties

The functional units of natural photosynthetic systems\ncontrol\nthe process of converting sunlight into chemical energy. In this article,\nwe explore a series of chemically and structurally modified bacteriochlorophyll\nand chlorophyll pigments through computational chemistry to evaluate\ntheir electronic spectroscopy properties. More specifically, we use\nmulticonfigurational and time-dependent density functional theory\nmethods, along with molecular dynamics simulations, to compute the\nmodels’ energetics both in an implicit and explicit solvent\nenvironment. Structural modifications aimed at reducing the planarity\nof the macrocycle through alkyl-bridge anchoring reveal the significant\nrole of the curvature in fine-tuning spectral properties, which mimics\nprotein scaffold effects on naturally occurring pigments. Furthermore,\nchemical substitutions with a carbonyl group show potential for expanding\nabsorption spectra toward the blue region, while incorporating an\nadditional double bond decreases absorption efficiency. These insights\nlay the groundwork to design novel synthetic pigments, with potential\napplications in artificial light-harvesting systems and more efficient\nphotovoltaic devices.