I expect the reader may now be wondering what all of this has got to do with the field of zeolite science. The connection emerged from my desire to take the insights gained from my work on metal atom cryochemistry and these classes of newfound nanomaterials out of the cold and into the real world of ambient temperatures where detailed studies of their structure, property, function, utility, and the relations between them could be undertaken . In this context it occurred to me that, because these low nuclearity Mn and MnLm nanomaterials were inherently metastable with respect to further undesired agglomeration reactions leading towards thermodynamically stable bulk materials, they had to be stabilized by some kind of surface protecting sheath and one way to accomplish this was to perform the nucleation and growth reactions within the voids of zeolites. This was the commencement of my early career relationship with zeolites as porous hosts for synthesizing and characterizing a variety of metal, semiconductor and insulator-based nanomaterials.
While this was a prolific and exciting phase of my materials chemistry and nanochemistry research there were aspects of the work that I found frustrating. One related to the scientific philosophy of the zeolite community whose conferences I would attend and discover to my dismay the narrow focus of their interests on the properties and applications of zeolites in catalysis or gas separation.
Being trained as a materials chemist I preferred to look at zeolites as solids filled with nanometer dimension voids and wondered how they could perform and compete in the advanced materials research space that was concerned more with their electrical, optical and magnetic properties and potential utility in areas such as electronic, optoelectronic, optical and photonic devices, information processing and storage media, photovoltaic, battery and fuel cells, photocatalysis, electrocatalysis and photoelectrochemistry, chemical sensors, chemical and pharmaceutical storage and delivery systems.
I worked with Edith Flanigen and Robert Bedard at Union Carbide in Tarrytown, New York for five years to reduce some of these new ideas to practice and our vision of the future direction of the field was expounded in a 1989 Advanced Materials paper in Angewandte Chemie written with co-authors Andreas Stein and Alex Kuperman entitled ‘Advanced Zeolite Materials Science’ . Today this is a vibrant field of basic research with a global reach, which has led to many examples of new technologies and it is satisfying to see that zeolite journals and conferences now include sessions on advanced zeolite materials science as well as their staple diet of zeolite catalysis, gas separation and ion-exchange applications.
Around this time Edith Flanigen’s Union Carbide team made the extraordinary discovery that microporous materials could be templated from many elements of the periodic table thereby greatly expanding the composition field of zeolites way beyond that of aluminosilicates and silicas. I was fortunate enough to join their research and development effort that focused attention on advanced materials applications of microporous metal chalcogenides, working on the novel idea of semiconductors filled with nanometer holes; these can be viewed as anti-dot superlattices to be compared with superlattices of semiconductor dots and were investigated for use in molecular size and shape specific chemical sensing, providing an early proof-of-concept of a electronic nose .