The self-assembly of non-toxic well-consumed small caffeine molecules into well-defined structures has important implications for future medical applications seeking to target the transport of small drugs in human body. Particularly, the solvation of the microenvironments of the self assembly ultimately dictates the interaction with the drug molecules and their therapeutic efficacy. We present femtosecond-resolved studies of the dynamics of aqueous solvation within self-assembled dimeric structure of caffeine molecules. We have placed small hydrophobic probes 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl) 4H-pyran (DCM), coumarin 500 (C500) into the caffeine dimer to enable spectroscopic examinations of the interior. While molecular modeling and NMR studies of the probes in the caffeine dimers reveal a well-defined location (stacked in between two caffeine molecules), dynamical light …