Novel Highly Luminescent Amine-Functionalized Bridged Silsesquioxanes

• Autor(a) principal: Pereira, Rui F. P.
• Data de Publicação: 2017
• Outros Autores: Nunes, Sílvia C, Toquer, Guillaume, Cardoso, Marita A, Valente, Artur J. M., Ferro, Marta C., Silva, Maria M., Carlos, Luís D., Ferreira, Rute A. Sá, de Zea Bermudez, Verónica
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10316/107607; https://doi.org/10.3389/fchem.2017.00131
• topic: bis[(3-trimethoxysilyl)propyl]amine; luminescence; morphology; sol-gel chemistry; solvent-assisted structuring

Amine-functionalized bridged silsesquioxanes (BSs) were synthesized from bis[(3-trimethoxysilyl)propyl] amine via a solvent-mediated route. BS-1 and BS-2 were obtained at neutral pH with sub- and stoichiometric amounts of water, respectively, and high tetrahydrofuran content. BS-3 was prepared with hyperstoichiometric water concentration, high tetrahydrofuran content, and hydrochloric acid. BS-4 was synthesized with hyperstoichiometric water concentration, high ethanol content, and sodium hydroxide. BS-1 and BS-2 were produced as transparent films, whereas BS-3 and BS-4 formed white powders. Face-to-face stacking of flat or folded lamellae yielded quasi-hydrophobic platelets with emission quantum yields of 0.05 ± 0.01 (BS-1 and BS-2) or superhydrophilic onion-like nanoparticles with exciting emission quantum yields of 0.38 ± 0.03 (BS-3) and 0.33 ± 0.04 (BS-4), respectively. The latter two values are the largest ever reported for amine-functionalized siloxane-based hybrids lacking aromatic groups. Fast Grotthus proton hopping between = [Formula: see text]/ = NH groups (BS-3) and = N-/ = NH groups (BS-4), promoted by H+ and OH- ions, respectively, and aided by short amine-amine contacts provided by the onion-like morphology, account for this unique optical behavior.