title: Direct Observation of Siloxane Chirality on Twisted and Helical Nanometric Amorphous Silica.
abstract: Synthesis of chiral inorganic or hybrid nanomaterials through sol-gel transcription of chiral organic templates has attracted a great deal of interest for more than a decade. However, the chiral nature of these inorganic matrices has never been directly observed. For the first time, we report a direct evaluation of chirality on noncrystalline silica chiral nanoribbons by vibrational circular dichroism (VCD) measurements. Strong Cotton effect around 1150-1000 cm-1from Si-O-Si asymmetric stretching vibration was observed. Surprisingly, calcination of these hybrid nanoribbons doubled the intensity of Cotton effects. On the basis of transmission electron microscopy observations, IR, VCD, NMR, and Raman spectroscopies, we demonstrate that the silica chirality originates from twisted siloxane network composed of chiral arrangement of the Si-O-Si bonds. Our findings clearly prove the presence of chiral organization of amorphous silica network, making them very promising chiral platforms for chiral recognition, optical applications, or asymmetric catalysis.
authors: Department of Applied Chemistry and Biochemistry, Kumamoto University , 2-39-1 Kurokami, Chuo-ku Kumamoto 860-8555, Japan.
authors: Yutaka
authors: Y
authors: Okazaki
authors: Institut des Sciences Moléculaires, (UMR5255 ISM), CNRS, University of Bordeaux , 33405 Talence, France.
authors: Thierry
authors: T
authors: Buffeteau
authors: Institut des Sciences Moléculaires, (UMR5255 ISM), CNRS, University of Bordeaux , 33405 Talence, France.
authors: Elise
authors: E
authors: Siurdyban
authors: Institut des Sciences Moléculaires, (UMR5255 ISM), CNRS, University of Bordeaux , 33405 Talence, France.
authors: David
authors: D
authors: Talaga
authors: Materials Development Department, Kumamoto Industrial Research Institute , 3-11-38 Higashimachi, Higashi-ku Kumamoto 862-0901, Japan.
authors: Naoya
authors: N
authors: Ryu
authors: Department of Applied Chemistry and Biochemistry, Kumamoto University , 2-39-1 Kurokami, Chuo-ku Kumamoto 860-8555, Japan.
authors: Ryohei
authors: R
authors: Yagi
authors: Institute of Chemistry and Biology of Membranes and Nanoobjects (UMR5248 CBMN), CNRS - Universite Bordeaux - Bordeaux INP , 2 rue Robert Escarpit, 33607 Pessac, France.
authors: Emilie
authors: E
authors: Pouget
authors: Department of Applied Chemistry and Biochemistry, Kumamoto University , 2-39-1 Kurokami, Chuo-ku Kumamoto 860-8555, Japan.|Kumamoto Institute for Photo-Electro Organics (PHOENICS) , 3-11-38 Higashimachi, Higashi-ku Kumamoto 862-0901, Japan.
authors: Makoto
authors: M
authors: Takafuji
authors: Department of Applied Chemistry and Biochemistry, Kumamoto University , 2-39-1 Kurokami, Chuo-ku Kumamoto 860-8555, Japan.|Kumamoto Institute for Photo-Electro Organics (PHOENICS) , 3-11-38 Higashimachi, Higashi-ku Kumamoto 862-0901, Japan.
authors: Hirotaka
authors: H
authors: Ihara
authors: Institute of Chemistry and Biology of Membranes and Nanoobjects (UMR5248 CBMN), CNRS - Universite Bordeaux - Bordeaux INP , 2 rue Robert Escarpit, 33607 Pessac, France.
authors: Reiko
authors: R
authors: Oda
keywords: Chiral nanostructures; VCD; chiral enhancement; chiral transcription; origin of inorganic chirality