TY - JOUR
AU - Pereira, Rui F. P.
AU - Nunes, Sílvia C.
AU - Toquer, Guillaume
AU - Cardoso, Marita A.
AU - Valente, Artur J. M.
AU - Ferro, Marta C.
AU - Silva, Maria M.
AU - Carlos, Luís D.
AU - Ferreira, Rute A. S.
AU - de Zea Bermudez, Verónica
PY - 2018
M3 - Original Research
TI - Novel Highly Luminescent Amine-Functionalized Bridged Silsesquioxanes
JO - Frontiers in Chemistry
UR - https://www.frontiersin.org/articles/10.3389/fchem.2017.00131
VL - 5
SN - 2296-2646
N2 - 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 = NH2+/ = 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.
ER -