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FRET-Selective and Ion-Exchange Responsive Smart Nano-GUMBOS from Functionalized Pyrene: First Observation of Excited State Aggregation (Exciaggremer) Inside Crystalline Nanoball

2020; American Chemical Society; Volume: 124; Issue: 8 Linguagem: Inglês

10.1021/acs.jpcc.9b09797

1932-7455

Prabal Pramanik, Sudhir Kumar Das, Mintu Halder,

Molecular Sensors and Ion Detection

In this report, a novel ionic-liquid-comprised group of uniform materials based on organic salt (GUMBOS) has been assembled by incorporating pyrene butyrate with quaternary phosphonium ionic liquid (IL) via simple ion-exchange process. By reprecipitation method, we have developed a new kind of water suspended crystalline pyrene assimilated nanoparticles, i.e., nanomaterials derived from a GUMBOS (nano-GUMBOS). The nanocrystallinity and the molecular level stacking of the aromatic fluorophores inside the nanoparticles have been confirmed by several spectroscopic, microscopic and calorimetric measurements. The fluorophore moieties within the nanocrystal have been found to show high propensity to undergo self-association upon excitation and exhibit new kind of excited state association induced emission (ESAIE). Here we have demonstrated the association of organic molecules in their electronic excited state (we name this as exciaggremer formation) for the first time which is attributed to something beyond the process of simple excimeric dimerization. Due to the presence of bathochromically shifted strong aggregation induced emission and hydrophobic scaffolds, this nanoparticle further promotes the fluorescence resonance energy transfer to several hydrophobic organic dyes unlike the free fluorophore in bulk solvent. Moreover, some soft anions like iodide can assist disintegration of the organic moieties form the ionic-liquid backbone that results in ion-exchange mediated freeing up of the fluorophores. This ion-exchange mediated disintegration can indeed become a new dimension in the area of sensing and delivery.