Editorial Cite This: Chem. Mater. 2018, 30, 4177−4178
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Chemistry of Materials 1k Club: Functionalized Hybrid Mesoporous Networks
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a few months later, Geoffrey Ozin’s group published a letter in Nature.4 More often than not, these three papers are cited together. Since then, the field of periodic mesoporous organosilicates (PMOs) has grown tremendously and has allowed chemists to decorate mesoporous materials with different functionalities at multiple sites. The designed complexity of these nanostructured materials has increased with time, and the materials have been investigated in the context of numerous applications, ranging from catalysis and molecular adsorption to bioimaging and therapeutic imaging. This concept of mixing and matching organic linkers with inorganic nodes is also seen in the highly successful area of metal organic frameworks, which has mushroomed in parallel with PMOs. CM: If you had to put your finger on it, what makes your article special? What are you most happy about when you reread it? AS: It was the right paper at the right time and it is solid work. In addition to describing the idea, synthesis, and structure of the new materials, we demonstrated the ability to carry out in situ chemical reactions with the functional bridges and tested properties, such as hydrophobicity and absorption of organics. In the days before voluminous Supporting Information, my students did a nice job providing extensive structural proof for the materials. One interesting property that I noticed on rereading the paper now and that we did not appreciate at the time, was the small size of the particles, closely approaching the nanoregime (Figure 2). Before we submitted the paper, we had some fun coming up with our own acronym for these novel materials, given the wide adoption of acronyms in the mesoporous materials field (MCM, SBA, FDU···). After some thought, we agreed on UOFMN to honor our institution (unified organically functionalized mesoporous networks, and the University of Minnesota). The first two candidates UOFMN-1 and UOFMN-2 were described in our paper. It turned out that our acronym was too specific and no one else adopted it. Instead, the less location-specific and hence more general acronym coined by Geoffrey Ozin (PMO) became the widely used name for this class of materials. We had a bigger impact in terms of acronyms when, around the same time, we coined the name 3DOM materials for three-dimensionally ordered macroporous materials prepared by colloidal crystal templating. This more general acronym has been widely adopted by the community around the world. CM: What’s your advice to young scientists trying to discover the next breakthrough in material science? AS: Looking back at our experience with the UOFMN material, I have a few recommendations. (1) While it is important to carry out careful analyses of new materials and desirable to optimize their properties, do not always wait for
he Chemistry of Materials 1k Club comprises authors whose papers in the journal have been cited 1000 times or more. The latest members of the club are Andreas Stein and the three coauthors of their 1999 Chemistry of Materials paper entitled “Mesoporous Sieves with Unified Hybrid Inorganic/ Organic Frameworks” (Figure 1).1,2 This paper is still being cited to this day and has had a profound influence on the area of mesoporous materials. In this work, the authors introduced the concept of unified organically functionalized mesoporous networks (UOFMN), in which both the organic and inorganic precursors are of a fixed stoichiometry and are covalently bonded. The elegance of the work derives from the clearly defined inorganic and organic chemistry principles as well as characterization methods (including extensive NMR analyses) applied to achieve a high level of morphological and chemical control over the final mesoporous materials products. We (Chemistry of Materials, CM) spoke with Professor Stein (AS) to ask him about his motivations and those of his coauthors at the time of writing this paper. CM: At what stage of your academic career were you when you submitted this article to Chemistry of Materials? Who were the other authors on the paper, and at what stage were they? Where are they now? AS: When we submitted our paper on “UOFMN materials”, I was an assistant professor in my final year before obtaining tenure at the University of Minnesota. Brian Melde, who synthesized the novel hybrid mesoporous materials, was a third-year Ph.D. student. He is now a research chemist at the US Naval Research Laboratory. Brian Holland (now at Stepan Company) and Chris Blanford (now a senior lecturer at the University of Manchester) were advanced Ph.D. students close to graduation, and they helped Brian with some of the materials characterization. CM: Given the high number of citations of this article, a significant amount of research has been impacted over the years. Where did you think the field was headed when you wrote the review? In your opinion, how has this particular research field evolved ever since? AS: At the time of writing our manuscript, the field of templated mesoporous materials had developed for about a decade. We and others had made contributions to hybrid mesoporous silica materials with organic functional groups that were attached to the silica surfaces either by grafting reactions or by inclusion of organoalkoxysilanes in the precursor mixture. A logical next step was to introduce organic groups into the silica walls themselves, using bis(alkoxysilyl)-based molecules to provide bridging groups of different types between silicon atoms. It is clear that the time was ripe for this idea because three research groups in three different countries independently published seminal papers around the same time: Shinji Inagaki’s group at Toyota in Japan published the first report of mesoporous materials with organic groups in their frameworks in the Journal of the American Chemical Society,3 we published our paper in Chemistry of Materials,1 and © 2018 American Chemical Society
Published: July 10, 2018 4177
DOI: 10.1021/acs.chemmater.8b02574 Chem. Mater. 2018, 30, 4177−4178
Chemistry of Materials
Editorial
Figure 1. New members of the Chemistry of Materials 1k Club: Corresponding author Andreas Stein, Brian Melde, Brian Holland, and Chris Blanford.
mesoporous organosilicates. The advice not to put all eggs in one basket would have been a good one.
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Carlos Toro, Managing Editor Jillian M. Buriak, Editor-in-Chief AUTHOR INFORMATION
ORCID
Jillian M. Buriak: 0000-0002-9567-4328 Notes
Views expressed in this editorial are those of the authors and not necessarily the views of the ACS.
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REFERENCES
(1) Melde, B. J.; Holland, B. T.; Blanford, C. F.; Stein, A. Mesoporous Sieves with Unified Hybrid Inorganic/Organic Frameworks. Chem. Mater. 1999, 11, 3302−3308. (2) Their paper, reference 1, has been cited 1029 times (Web of Science) and 1274 times (Google Scholar) as of June 16, 2018. (3) Inagaki, S.; Guan, S.; Fukushima, Y.; Ohsuna, T.; Terasaki, O. Novel Mesoporous Materials with a Uniform Distribution of Organic Groups and Inorganic Oxide in Their Frameworks. J. Am. Chem. Soc. 1999, 121, 9611−9614. (4) Asefa, T.; MacLachlan, M. J.; Coombs, N.; Ozin, G. A. Periodic Mesoporous Organosilicas with Organic Groups Inside the Channel Walls. Nature 1999, 402, 867. (5) Holland, B. T.; Blanford, C. F.; Do, T.; Stein, A. Synthesis of Highly Ordered, Three-Dimensional, Macroporous Structures of Amorphous or Crystalline Inorganic Oxides, Phosphates, and Hybrid Composites. Chem. Mater. 1999, 11, 795.
Figure 2. Cryo-TEM of one of their mesoporous network materials, showing the channels within the silicate particle. Reprinted with permission from the American Chemical Society from ref 1.
100% perfection before publishing. If it is important work, that perfection can come in follow-up work by you and others. I found the first entry in Brian’s lab book for these materials dated August 1997. Why did we wait until 1999 to publish? An important reason was to characterize the materials thoroughly. But another reason for the delay was our original goal to form materials with similar beautiful symmetry as the MCM-41 mesoporous silica structures that had inspired us. In the end, we achieved “only” worm-like structures under the reaction conditions we used and published anyway. If we had waited any longer, we would have “joined the bandwagon”. (2) Sometimes, as in our case, the time is ripe for an idea, and you will find that other groups publish work on “your idea”. Do not think of this necessarily as “getting scooped”. Having multiple groups work on an idea not only drives the field through competition, but it provides critical mass. If we had been alone, the field might not have expanded in the way it has. (3) At the time we worked on UOFMN materials, we had also begun to lay the groundwork in the area of colloidal crystal templating of 3DOM materials. Given my small group size at the time, I chose to place greater emphasis on that research direction. This has certainly been a highly fruitful pursuit, and our 1999 Chemistry of Materials paper in that area is well on its way to also joining the 1k Club.5 But both Brian and I have sometimes regretted that we did not put the same emphasis on periodic 4178
DOI: 10.1021/acs.chemmater.8b02574 Chem. Mater. 2018, 30, 4177−4178
