Pillared Layered Compounds: Their Synthesis, Structure, and Properties

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This project will focus on two new families of porous materials, newly synthesized and characterized by the PI, with surface areas of 400-600 m2/g and pores in the range of 10-20A. One family consists of organic-inorganic hybrids prepared from alpha, omega-diphosphonic acids interacting with metals in non-aqueous solvents. These compounds contain cavities within a framework of metal phosphate like layers bridged by alkyl or aryl groups of the phosphonic acid. The aryl groups are amenable to functionalization by sulfonic acid groups which converts them into highly reactive Bronsted acids. The aim is to now provide a variety of functionalities, control hydrophobic-hydrophilic character and pore size of these products. The sorption and separation capabilities and catalytic behavior of the compounds as to their combined chemical selectivity and size selective behavior will be probed. The second family of porous materials consists of transition metal oxides-combined with either silica or zirconia also with pores in the 10-20A range prepared in alcohol with hexylamine templates. These two families bridge the gap between zeolites and the new mesoporous materials. They should therefore serve needs in separations science, ion exchange, sensors and catalysis for which other materials are unsuitable. The structure and characterization of these materials will require the use of a broad spectrum of spectroscopic, diffraction and surface tools providing ample opportunities for students to be trained using state of the science equipment in the latest techniques of materials chemistry. This study will be assisted by collaboration with groups in Spain, Poland and India.%%% Porous materials have a variety of uses in separating molecules based upon size, have extensive use in catalysis, sensors, drug delivery, ion exchange and nanoscience. Among the best examples are zeolites, used extensively for most of these purposes but best known as improving the yield of gasoline and home heating oil in petroleum cracking. A disadvantage is that their useful cavities are small, less than 1 nanometer (nm) or one millionth of an inch. A decade ago a new family of inorganic porous materials was discovered with narrow distribution of pores in the 2 to 15 nm range and many potential uses.Two new families of porous materials with pores in the 1 to 2 nm range, just the size that has largely been missin, has been discovered. One group of materials contain organic as well as inorganic groups and can be altered to attract different classes of medium sized molecules for separations, drug delivery and catalytic transformations. The second group is totally inorganic to be used mostly in catalysis as almost any catalytically active metal oxide can be prepared in this form. This research will require the training of students to utilize the state of the science equipment and the latest techniques of materials chemistry. The research will be assisted by collaboration with groups in Spain, Poland and India as well as undergraduates, graduate students and post-doctoral students at Texas A&M University.