Incorporation of isolated Ti sites into mesoporous silica thin films by sugar surfactant complexation

Mohammed Shahidur Rahman, Jyothirmai Ambati, Suvid Joshi, Stephen E. Rankin

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


One of the challenges in transition metal heterogeneous catalysis is the generation of supports with well-defined porosity containing transition metal sites of uniform coordination, complexity, and spacing. For instance, tetrahedrally coordinated titanium atoms incorporated into a silica network are believed to be the active oxidation sites for heterogeneous epoxidation catalysis. Sol-gel chemistry provides an opportunity to produce well mixed metal oxides, but the high reactivity of titanium precursors compared to silicon precursors impedes the uniform incorporation of isolated tetracoordinated Ti(IV) sites. Here, a homogeneous distribution of titanium at the pore surface is promoted by a ligand-assisted templating method with n-dodecyl β-d-maltoside (C12G2) surfactant. Preferential interactions or complexation between the titanium and maltose headgroups of this surfactant are hypothesized to promote homogeneous incorporation of titania only at the micelle/silica interface. To generate well-ordered materials with controlled titania site density, a mixed surfactant system of C 12G2 and cetyltrimethylammonium bromide (C 16TAB) is used for pore templating. A series of Si-Ti mixed oxide thin films with different levels of titanium loading (from 1.15 to 11.1 atom% of cations) is synthesized by a solvent evaporation-driven self-assembly method with staged precursor addition to facilitate complexation between C 12G2 and the titanium precursor. The degrees of homogeneity (indicated by tetracoordinated Ti) in these films are compared with those of films synthesized with the same loading of titanium but without C 12G2 surfactant or without pre-complexation. The titanium in films synthesized using maltoside complexation is highly dispersed, while some fraction of octahedrally coordinated titanium atoms is generated without C12G2 surfactant and without pre-complexation.

Original languageEnglish
Pages (from-to)74-83
Number of pages10
JournalMicroporous and Mesoporous Materials
StatePublished - May 15 2014

Bibliographical note

Funding Information:
This material is based upon initial film synthesis work supported by the National Science Foundation under Grant No. CBET-0967390 and the Kentucky Science and Engineering Foundation under Grant No. KSEF-1204-RDE-009 , and further characterization by FTIR and XRD performed as part of a U.S. Department of Energy EPSCoR Implementation Award under Grant number DE-FG02-07ER46375. We thank Prof. Barbara Knutson for access to the UV–vis spectrometer and Dr. Alan Dozier for help with STEM.


  • Complexation
  • Mixed surfactant
  • Self-assembly
  • Templating
  • Titanosilicate

ASJC Scopus subject areas

  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials


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