biostudies-literatureUnknown16(31)Vinod KEumelanin, a ubiquitous pigment in animals, is known for its ability to protect against UV-induced damage by efficiently dissipating energy as heat. Despite its importance, the mechanisms underlying eumelanin's broadband absorption and ultrafast energy relaxation remain unclear, primarily due to the inherent structural complexity of the pigment. To address this, we employed model eumelanin multimers, including a monomer (DMICE), dimer (DMICE-D), and trimer (DMICE-T), and investigated their optical properties in both solution and aggregated thin films. Our results reveal that increasing multimer size and aggregation significantly broaden the absorption spectrum, a phenomenon attributed to amplified excitonic interactions. The non-radiative decay processes, governed by internal conversion anChemical science14304-14313https://www.ebi.ac.uk/biostudies/studies/S-EPMC12243186biostudies-literatureStructural disorder as a key to photoprotection in eumelanin multimers.PMC12243186Thomas DVinod KHariharan MfalseStructural disorder as a key to photoprotection in eumelanin multimers.Eumelanin, a ubiquitous pigment in animals, is known for its ability to protect against UV-induced damage by efficiently dissipating energy as heat. Despite its importance, the mechanisms underlying eumelanin's broadband absorption and ultrafast energy relaxation remain unclear, primarily due to the inherent structural complexity of the pigment. To address this, we employed model eumelanin multimers, including a monomer (DMICE), dimer (DMICE-D), and trimer (DMICE-T), and investigated their optical properties in both solution and aggregated thin films. Our results reveal that increasing multimer size and aggregation significantly broaden the absorption spectrum, a phenomenon attributed to amplified excitonic interactions. The non-radiative decay processes, governed by internal conversion an2025-01-01T00:00:00Z2025 Aug2026-03-31T11:45:22.301Z2025-09-01T03:05:45.806ZS-EPMC122431864065653210.1039/d5sc00920k