caa a22 4500 445328738 CHVBK 20180317142730.0 cr unu---uuuuu 170323e20110201xx s 000 0 eng 10.1007/s10953-011-9648-8 doi (NATIONALLICENCE)springer-10.1007/s10953-011-9648-8 Complexation of Silicic Acid with Tiron in Aqueous Solution Under near Natural Condition [Elektronische Daten] [Shuqin Bai, Yutaka Tsuji, Yoshihiro Okaue, Takushi Yokoyama] The formation of a silicic acid-tiron (a derivative of catechol) complex was investigated in aqueous solution with various molar ratios of tiron to silicic acid (tiron/Si) or with various pH using 29Si NMR. Only the 1:3 silicic acid-tiron complex was detected in despite of the range of tiron/Si molar ratios. This complex is stable in the pH range from 6 to 10. This indicates that the formation of a hydrogen bond (SiOH⋅⋅⋅O− in tiron), due to dissociation of H+ from hydroxy groups of tiron, may be a trigger for the formation of the complex. Around pH=6, the formation of the complex occurs when the tiron/Si molar ratio is larger than 3 and most of silicic acid is converted to the complex when the ratio is larger than 25. Based on the temperature dependence of the 29Si NMR spectra for the complex, the existence of two possible meridional and facial isomers was confirmed. The conditional formation constant for the 1:3 silicic acid-tiron complex was defined as Eq.8 and estimated to be 2.0 mol−1⋅dm3 for the facial complex and 4.1 mol−1⋅dm3 for the meridional complex, respectively. Springer Science+Business Media, LLC, 2011 Silicic acid nationallicence Tiron nationallicence 29Si NMR nationallicence Complexation nationallicence Conditional formation constant nationallicence Bai Shuqin College of Environment and Resources, Inner Mongolia University, No. 235 West University Street, 010021, Hohhot, Inner Mongolia, P.R. China aut Tsuji Yutaka Kurume National College of Technology, Komorino, 830-8555, Kurume, Japan aut Okaue Yoshihiro Department of Chemistry, Faculty of Sciences, Kyushu University, 810-8560, Hakozaki, Higashi-ku, Fukuoka, Japan aut Yokoyama Takushi Department of Chemistry, Faculty of Sciences, Kyushu University, 810-8560, Hakozaki, Higashi-ku, Fukuoka, Japan aut Journal of Solution Chemistry Springer US; http://www.springer-ny.com 40/2(2011-02-01), 348-356 0095-9782 40:2<348 2011 40 10953 https://doi.org/10.1007/s10953-011-9648-8 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10953-011-9648-8 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Bai Shuqin College of Environment and Resources, Inner Mongolia University, No. 235 West University Street, 010021, Hohhot, Inner Mongolia, P.R. China aut NATIONALLICENCE 700 1- Tsuji Yutaka Kurume National College of Technology, Komorino, 830-8555, Kurume, Japan aut NATIONALLICENCE 700 1- Okaue Yoshihiro Department of Chemistry, Faculty of Sciences, Kyushu University, 810-8560, Hakozaki, Higashi-ku, Fukuoka, Japan aut NATIONALLICENCE 700 1- Yokoyama Takushi Department of Chemistry, Faculty of Sciences, Kyushu University, 810-8560, Hakozaki, Higashi-ku, Fukuoka, Japan aut NATIONALLICENCE 773 0- Journal of Solution Chemistry Springer US; http://www.springer-ny.com 40/2(2011-02-01), 348-356 0095-9782 40:2<348 2011 40 10953 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer