Absorption and exciton emission by an aggregated cyanine dye occluded within mesoporous SBA-15

We report the formation of monomeric and J-aggregated 1,1'-diethyl-3,3'-di(4-sulfobutyl)-5,5',6,6'-tetrachlorobenzimidazolocarbocyanine (referred to as TDBC) encapsulated within a silicate mesostructure, specifically SBA-15, under different pH conditions. To facilitate incorporation of TDBC, it was necessary to functionalize the interface of the synthesized SBA-15 for proper guest-host electrostatic interaction between the anionic dye and the inner core surface charge, through use of a silylation reagent, (aminopropyl)triethoxysilane, which at high pH values results in formation of -NH3+ surface species. XRD, UV-vis absorption and fluorescence measurements are used as spectroscopic tools to characterize SBA-15 host samples as well as composites consisting of the host and encapsulated molecules. J-aggregated TDBC occluded within SBA-15 represents a robust, new superradiant fluorescent nanomaterial.