Photophysical study of the aggregation of naphthyl-, anthryl- and pyrenyl-adamantanebisurea derivatives

Adamantaneurea derivatives 1–13 were synthesized and their photophysical properties investigated. The compounds 1–13 are comprised of a rigid adamantane moiety, 1 or 2 urea groups and different chromophores, as well as methylene spacer between the adamantane and the urea and/or between the urea and the chromophores. Fluorescence quantum yields and singlet excited state lifetimes were measured in CH3CN and DMSO. It was found that molecules with methylene spacer between the adamantane and the urea aggregate in CH3CN, whereas aggregation was not observed in DMSO. The highest tendency to aggregation was observed for 9-aminoanthracene derivative 10 and pyrene derivative 13 which aggregate in both solvents. The aggregation probably takes place due to intermolecular H-bonds between the ureas and π,π-stacking of the aromatic chromophores. Pyrene 13 probably gives rise to excimers and intermolecular aggregates.