We present spectroscopic, crystallographic, DFT, and antifungal studies of the imine coumarin, ICOU [7-(3,5- diiodohydroxybenzylideneamino)-4-methylcoumarin]. The spectroscopic and photophysical properties of ICOU were investigated using stationary UV-Vis spectroscopy, fluorescence spectroscopy with resonance light scat- tering (RLS), and fluorescence lifetime measurements using time-correlated single photon counting (TCSPC). Studies have shown that ICOU molecules exhibit a strong tendency to aggregate (dimerize). Fluorescence spectra revealed dual-band emission, attributed to monomer and dimer emission, indicating a dependence of the monomer/dimer equilibrium on the environment. Crystallographic analyses confirmed the presence of dimers, primarily in the card pack conformation, and at higher concentrations, additional aggregation interactions were observed. The spectroscopic and crystallographic results were supported by DFT calculations, which determined the energies of the formed aggregates. Furthermore, the antifungal potential of ICOU against cereal fungal pathogens was assessed. This compound, which has been previously published and demonstrated very high antifungal potential, also represents a promising compound in the fight against increasingly dangerous crop pathogens. It is worth noting that this study documents the ICOU molecule as exhibiting interesting spectroscopic properties and exhibiting properties that may be important in the fight against cereal pathogens, which could translate into benefits for modern sustainable agriculture and food production.