Multichromophoric cyclodextrins. 1. Synthesis of O-naphthoyl-灏?cyclodextrins and investigation of excimer formation and energy hopping was written by Berberan-Santos, Mario N.;Canceill, Josette;Brochon, Jean Claude;Jullien, Ludovic;Lehn, Jean Marie;Pouget, Jacques;Tauc, Patrick;Valeur, Bernard. And the article was included in Journal of the American Chemical Society in 1992.Formula: C42H63Br7O28 This article mentions the following:
The synthesis and photophys. properties of 灏?cyclodextrins bearing seven 2-naphthoyloxy chromophores in specific positions, either on the primary face or the secondary face, or 14 naphthoyloxy chromophores, seven on each face, are reported. These multichromophoric cyclodextrins are good models for the study of excitation energy migration among chromophores in well-defined positions. The investigation was performed in CH2Cl2 and in a mixture of EtOH and MeOH that can form in a glass at low temperature The absorption spectra show that the interactions between chromophores in the ground state are weak, whereas the fluorescence spectra reveal the existence of excimers at room temperature but not at low temperature in a rigid glass. Further evidence of excimer formation is provided by the fluorescence decays. Since excimers act as energy traps, the energy hopping process was studied in a rigid glass at low temperature by steady-state and time-resolved fluorescence depolarization techniques. The steady-state anisotropy is found to be one seventh of the theor. limiting anisotropy 0.4, which means that excitation energy hops between chromophores with essentially randomly oriented transition moments at a rate much higher than the chromophore intrinsic decay rate. Energy hopping is indeed very fast as shown by the fluorescence anisotropy decay which is at least as fast as the apparatus time resolution (a few tens of picoseconds). In the experiment, the researchers used many compounds, for example, Heptakis(6-Bromo-6-Deoxy)-灏?Cyclodextrin (cas: 53784-83-1Formula: C42H63Br7O28).
Heptakis(6-Bromo-6-Deoxy)-灏?Cyclodextrin (cas: 53784-83-1) belongs to organobromine compounds. Bromo compounds are employed in a variety of metal-catalyzed coupling reactions. They are also ideal candidates for the synthesis of Grignard reagents that have wide-applicability in organic synthesis. alpha-Bromoesters are employed in the Reformatsky reaction for the synthesis of beta-hydroxyesters. The reactivity of organobromine compounds resembles but is intermediate between the reactivity of organochlorine and organoiodine compounds. For many applications, organobromides represent a compromise of reactivity and cost.Formula: C42H63Br7O28
Referemce:
Bromide – Wikipedia,
bromide – Wiktionary