CHEMICAL & ENGINEERING
NEWS OF THE WEEK MARCH 25, 2002 - EDITED BY JANICE LONG & JANET S. DODD
MATERIALS
SCIENCE
world have been looking for materials with periodicity in the walls," he says, "thisfindingcan be considered a breakthrough." To make the hybrid, Inagaki and coworkers begin with an organosilane monomer, (C2H50)3Si-C6H4-Si(C2H50)3, useful. Most striking, the pore that they heat in basic solution walls themselves are completely with a surfactant template. They regular, composed of orderly lay- think interactions among indiers of benzene rings linked to al- vidual precursor molecules, as ternating layers of silicate chains. well as among the precursors and The benzene rings can be func- the surfactant, direct the assemtionalized, opening the door to bly into an ordered framework. the vast range of organic trans"We can control the pore size formations that can lead to spe- using different-sized surfactants, cially tailored properties [Nature, such as alkyltrimetJiylammonium 416,304(2002)}. compounds with various alkyl "To date, all conventional chain lengths and triblock copolymesoporous materials have had mers," Inagaki says. By varying amorphous pore-wall structures the surfactant, the group has synthat restrict their applications," thesized hybrids with pore diamnotes chemist Shinji Inagaki, eters ranging between 30 and 50 leader of the Frontier Research Â. No matter what the pore size, Group at Toyota Central R&D all the materials had the same regLaboratories, Nagakute. Inagaki ular arrangement in the walls. synthesized and characterized In a step that could prove of the new material with visiting re- practical importance in the near searcher Shiyou Guan and To- term, Inagaki's team sulfonated hoku University physics profes- the material without destroying sors Tetsu Ohsuna and Osamu its meso- or molecular-scale peTerasaki. riodicity The resulting sulfonic "Our discovery of a synthetic acid-functionalized mesoporous approach to formation of meso- material has "great potential as a porous materials with crystalline solid acid catalyst for eco-friendpore walls will open a newfieldof ly chemical processes and as an materials science due to their electrolyte for fuel cells," Inagameso- and molecular-scale hier- ki says. Both the sulfonated and archically ordered structures," In- unsulfonated materials are stable agaki tells C&EN. "The result will up to 500 °C in air or nitrogen. impact a wide range of research "The future of these kinds of fields—not only catalysis and ad- materials will be very great since sorption, but also electrical, mag- they are opening the possibility netic, and optical devices." of controlling chemical and physProfessor Ferdi Schuth of the ical properties in the pores and in Max Planck Institute for Coal the framework at the same time," Research agrees that the Toyota notes chemistry professor Robresearch represents a significant ert J. P. Corriu of the University advance. Schùth is chair of the of Montpellier, France, who also International Zeolite Associa- carries out research in the area. tion's new Commission on Or- "They are opening wide possidered Mesoporous Materials. bilities in materials science and "Since researchers all over the catalysis."-PAMELA ZURER
A BEAUTIFUL MELD
Benzene-silica hybrid assembles into framework with crystalline pore walls
W
HETHER PLANT BREEDER
or chemist, hybridizers hope to blend the best features of the parents into optimal offspring. That's what a team of scientists in Japan has accomplished with the creation of a benzene-silica hybrid that assembles itself into a crystalline mesoporous material. The new material exhibits the periodic array of medium-sized pores that have made inorganic mesoporous molecular sieves so
HIGH ORDERS Alternating rings of hydrophobic benzene layers and hydrophilic silicate layers make up crystalline walls of mesoporous solid. The channels, in turn, line up in a hexagonal array. In this model of the pore surface, silicon atoms are shown as orange; oxygen, red; carbon, white; and hydrogen, yellow.
8
C&EN / MARCH 25. 2002
HTTP://PUBS.ACS.ORG/CEN
