Boosting the Emission Quantum Yield of Urea Cross-Linked Tripodal Poly(oxypropylene)/Siloxane Hybrids Through the Variation of Catalyst Concentration
authors Freitas, VT; Lima, PP; Bermudez, VD; Ferreira, RAS; Carlos, LD
nationality International
journal EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
author keywords Organic-inorganic hybrid composites; Sol-gel processes; Luminescence; Quantum yield
keywords CARBOXYLIC-ACID SOLVOLYSIS; METAL ACTIVATOR IONS; BRIDGED SILSESQUIOXANES; LIGHT EMISSION; PHOTOLUMINESCENCE; PHOSPHORS
abstract Transparent monoliths of urea cross-linked tripodal siloxane-based hybrids, named tri-ureasils, were prepared by the solgel process, using a wide concentration range of hydrochloric acid catalyst (1.0 x 10(-3) = [HCl] <= 2.0 M). The gelation time of the monoliths was controlled by varying the amount of water (2.2 and 22.2 mmol) and HCl (between 4.0 x 10(-5) and 8.0 x 10(-2) mmol) incorporated. Their local structure was characterized by X-ray diffraction, Si-29 and C-13 nuclear magnetic resonance, mid-infrared and ultraviolet/visible absorption spectroscopy, and photoluminescence in steady-state and time resolved modes. The effect of [HCl] in the enhancement of the emission quantum yield was quantified. Although all the hybrids display emission at room temperature in the blue spectral region, it was observed that maximum and constant quantum yield values of 0.13 +/- 0.01 are achieved for 0.01 <= [HCl] <= 0.1 M.
publisher WILEY-V C H VERLAG GMBH
issn 1434-1948
year published 2012
issue 32
beginning page 5390
ending page 5395
digital object identifier (doi) 10.1002/ejic.201200823
web of science category Chemistry, Inorganic & Nuclear
subject category Chemistry
unique article identifier WOS:000310687300033

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