The use of molecular probes for the characterization of dispersions of functionalized silica nanoparticles.
Butoxylated silica nanoparticles (BSN) were prepared by esterification of the silanol groups of fumed silica nanoparticles with butanol and characterized by 13C and 29Si NMR and thermogravimetry. The molecular probes benzophenone (BP) and safranine-T were used to investigate the BSN suspensions in water:acetonitrile. Laser flash-photolysis experiments at lambda(exc)=266 nm performed with BSN suspended in acetonitrile:aqueous phosphate buffer supported previous results of our group obtained by time-resolved phosphorescence experiments and showed that only free and adsorbed excited triplet states of BP and diphenylketyl radicals contribute to the signals. The UV-vis spectroscopic and photophysical properties of safranine-T are strongly solvent-dependent. Thus, the analysis of the emission spectra and fluorescence lifetimes yielded information on the localization of this probe molecule in suspensions of BSN and of the bare silica nanoparticles. The values of the equilibrium constant for the adsorption of the ground-state safranine-T on the particles were found to be (9.2+/-0.8)x10(4), (7.2+/-0.8)x10(5), and (3.0+/-0.1)x10(4) for the BSN in 1:1 acetonitrile:water, SiO2 in 1:1 acetonitrile:water, and SiO2 in acetonitrile, respectively.
Arce
Valeria B
VB
Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), LADECOR, Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina.
Bertolotti
Sonia G
SG
Oliveira
Fernando J V E
FJ
Airoldi
Claudio
C
Gonzalez
Mónica C
MC
Allegretti
Patricia E
PE
Mártire
Daniel O
DO
D000327:Adsorption; D001577:Benzophenones / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D015335:Molecular Probes / Q000032:analysis* / Q000737:chemistry*; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry*; D010619:Phenazines / Q000737:chemistry; D012822:Silicon Dioxide / Q000032:analysis* / Q000737:chemistry*; D012996:Solutions; D013696:Temperature
D001577:Benzophenones; D015335:Molecular Probes; D010619:Phenazines; D012996:Solutions; C047723:benzophenone; D012822:Silicon Dioxide; C009195:safranine T