Matrix-assisted laser desorption/ionisation mass spectrometry in the study of polycondensation of Ti(OBun)4 in the presence of Si(OEt)4.
The hydrolysis-polycondensation behaviour of alcoholic solutions containing Si(OEt)4 and Ti(OBun)4, in different molar ratios (Si/Ti = 10-0.2), was analysed by laser desorption/ionisation (LDI) and matrix-assisted laser desorption/ionisation (MALDI) mass spectrometry. The solutions were prepared using operating conditions usually employed in the sol-gel synthesis of SiO2-TiO2 materials. In accord with the well-known procedures for controlling the different chemical reactivities of the alkoxides, the pre-hydrolysis of the slower reacting silicon ethoxide and the chelation by acetylacetone of the faster reacting titanium butoxide were performed before mass spectrometric analysis. While LDI-MS did not provide evidence for the presence of mixed Si-Ti species in samples obtained from these reactions, MALDI-MS of samples diluted with chloroform and using 2,5-dihydroxybenzoic acid (DHB) as matrix led to detection of various oligomers with different contents of Si and Ti atoms. The results suggest that the formation of Si-Ti mixed oligomers seems to be the favoured process, especially for solutions in which one of the two components is diluted.
Seraglia
Roberta
R
CNR-ISTM, Istituto di Scienze e Tecnologie Molecolari, Via Marzolo 1, 35100 Padova, Italy. roberta.seraglia@adr.pd.cnr.it
Armelao
Lidia
L
Cristoni
Simone
S
Gross
Silvia
S
Tondello
Eugenio
E
Traldi
Pietro
P
D000465:Algorithms; D001711:Biotransformation; D002851:Chromatography, High Pressure Liquid; D020117:Cisapride / Q000737:chemistry / Q000493:pharmacokinetics; D005444:Flunarizine / Q000737:chemistry / Q000493:pharmacokinetics; D006801:Humans; D066298:In Vitro Techniques; D013058:Mass Spectrometry; D008862:Microsomes, Liver / Q000737:chemistry / Q000378:metabolism; D004364:Pharmaceutical Preparations / Q000737:chemistry / Q000378:metabolism*; D010599:Pharmacokinetics; D011433:Propranolol / Q000737:chemistry / Q000493:pharmacokinetics; D014700:Verapamil / Q000737:chemistry / Q000493:pharmacokinetics
D004364:Pharmaceutical Preparations; D011433:Propranolol; D014700:Verapamil; D005444:Flunarizine; D020117:Cisapride