So Far, Fullerene Studies Dominate Chemical Citations In The 1990s

Sidebar:The Most-Cited Chemistry Papers of 1991-93 chemistry papers published from 1991 to 1993 and reported in the July/August 1994 issue of the newsletter Science Watch, articles on fullerenes and related molecules still are among the most cited in the field. The dominance of fullerenes aside, several other areas of chemistry are also on the move: asymmetric synthesis, surface chemistry, computational chemistry, macromolecular structures, and new reagents. This analysis was conducted using the Science Citation Index of the Philadelphia-based Institute for Scientific Information (ISI). Following is Science Watch's report, written for the newsletter by John Emsley, science writer in residence at the department of chemistry, Imperial College, London. The article is reprinted with the permission of Science Watch and ISI, its publisher. Government agencies need an objective assessment of the scientists and research that they are expected to fund. So do independent or charity-based research institutes, whose trustees must also closely monitor what their staff is achieving. And so does industry--although people there are often better placed to understand what is going on, whom to sponsor, and what the return on the investment will be. The Science Citation Index (SCI) provides one means of objective assessment. SCI logs every new paper as it appears and subsequently records its citations by other researchers. In general, the more a paper is cited, the more important that piece of work is. It is part of my role as science writer in residence at Imperial College, London, to keep in touch with the active areas of my subject--chemistry. If I were asked to indicate the most interesting areas at the moment I would say asymmetric synthesis, surface chemistry, new materials, molecular recognition, self-replication, catalysis, analysis, and molecular modeling. I would also include fullerenes (sometimes called buckminsterfullerenes, after architect R. Buckminster Fuller), the best example of which is the C60 carbon soccerball-shaped molecule. But I would not give them undue emphasis. When I spoke to the editors of Science Watch and asked if there was any way of confirming my intuitive choices, they offered to carry out a three-year analysis of chemistry papers and their citations. There duly arrived a complete printout of all chemistry papers published for the years 1991-93 that had collected 10 or more citations. * papers attracting 50 or more citations; n=131 ** papers attracting 25 or more citations; n=125 *** papers attracting 10 or more citations; n=16 Source:ISI's Science Indicators Database, 1991-93< SUBJECT1991*1992**1993*** Fullerenes and carbon tubules464263 Surface chemistry and semiconductors 912 0 Organic and asymmetric synthesis 911 6 Theory (includes computational) 9 9 0 Natural and biologically active products 8 613 Organometallic Chemistry 5 4 0 Analytical techniques 5 313 Molecular recognition and self-assembly 4 3 0 Polymers 3 0 0 Proteins 2 5 0 Others 1 4 6 What was I to make of these raw data? There were thousands of papers, but relatively few that were highly cited. The top-cited papers for 1991-93 are shown in the table on page 15. Of these, 29 had attracted more than 100 citations. All of these papers were published in 1991, as we might expect. Most are about fullerene chemistry. Discovered in the mid-1980s, fullerenes immediately seized the imagination of chemists in all branches of the field: organic, inorganic, physical, and theoretical. A more detailed analysis of the papers of each year is needed to eliminate the distorting presence of fullerenes. I chose a progressively less demanding cut-off point for each year: 50 citations or more for 1991 papers; 25 or more for 1992 papers; and 10 for 1993 papers. I then grouped them under several subject headings (see table on this page). In 1991's crop of papers, 29 were cited more than 100 times, with 21 of these devoted to fullerenes. The nonfullerene papers fall into the following categories: computational chemistry, protein structure, molecular recognition, substituent constants, mass spectra of biopolymers, and the immunosuppressant FK-506. The most-cited paper of 1991--cited 280 times (attracting 227 of these in 1993)--is about protein structure and was published in the Journal of Applied Crystallography. It was by Per Kraulis, then of Cambridge University, United Kingdom, and describes a program to produce schematic plots of protein structures. Although this paper appeared in what is essentially a structural chemistry journal, it has naturally also been cited by molecular biologists. It might have been expected that many of these highly cited papers would be review articles, which tend to attract more citations than individual papers, but this appears not to be the case. Of the top 10 for 1991, only two papers fall into this category (one in Chemical Reviews and one in Angewandte Chemie International Edition). Of the others, two are in Nature, two in Science, and one in the Journal of the American Chemical Society. Nature and Science, of course, publish across all branches of science and are eagerly read by all kinds of scientists. Clearly, if you want to be highly cited in chemistry, it pays to be published where there are the most readers. Another surprising feature of the top 29 papers is the high proportion that originate from industrial laboratories. AT&T Bell Laboratories in Murray Hill, N.J., has four on fullerenes; IBM Almaden Research Center in San Jose, Calif., has three, again all on fullerenes; and Dupont Co., Wilmington, Del., has one, also on fullerenes. The papers published in 1991 with between 50 and 100 citations give a better picture of the year. There were 102 that fell into this group. Although fullerenes still account for 39 of them, other areas were clearly represented, including surface chemistry (12 papers); asymmetric synthesis (12 papers); theoretical or computational chemistry (nine papers); biologically active molecules and natural products (nine papers); organometallics/clusters (seven papers); and analytical techniques (six papers). Surface chemistry has received a boost with the introduction of such new techniques as scanning tunneling microscopy (STM), which now allow surfaces to be examined atom by atom. Asymmetric synthesis and its importance in the preparation of biologically active molecules both have commanding positions on the list. Again in 1992 it is possible to impose the more demanding test of 50 or more citations, but only 16 papers that were published in 1992 fall into this category. The most-cited paper of 1992 collected 95 citations and is about fullerenes--and so is the second-most-cited paper. Paper No. 3, however, is about an organic process--asymmetric dihydroxylation--which is catalyzed by osmium. This work was done by K. Barry Sharpless's group at the Scripps Research Institute in La Jolla, Calif. Of the remaining papers, 11 are devoted to fullerenes, and three involve organometallic compounds. Clearly, imposing a higher number of citations does not reveal other key areas, so I fell back on a more reasonable limit of 25-50 citations. This produced a further 109 papers, and these were grouped in general classes that reflect those of 1991. The most significant change between 1991 and 1992 was the emergence of protein chemistry as an active area. No paper in 1993 collected 50 citations, which would be a truly remarkable feat. Indeed, only one paper collected more than 25 citations, whereas 16 papers collected 10 or more citations. Ten of these 16 are about fullerenes or the related carbon tubules. The remaining six papers deal with subjects previously mentioned: spectroscopic analytical techniques (two papers); biologically important systems--specifically the enzyme nitrogenase and porphyrins (two papers); the immunosuppressant FK-506 (one paper); and luminescent silicon colloids (one paper). This last paper on colloids comes from the AT&T Bell Labs. Closer inspection also reveals a noticeable change in the direction of fullerene research in 1993. Several papers are about ways of making more stable derivatives. This is a worthwhile goal to aim for because C60 itself decomposes in air. One paper from 1993--authored by C.C. Henderson and P.A. Cahill of the Sandia National Laboratories in Albuquerque, N.M.--claims the first C60 hydrocarbon of formula C60 H2. So what do citations tell us about chemistry in the 1990s? They reveal that fullerenes are of great interest and that those in the fullerene field tend to cite a few papers disproportionately often. Pulling aside the veil of fullerenes reveals other active areas in chemistry: asymmetric synthesis and the objects of this--such as new drugs and natural products; surface chemistry, which impinges on semiconductors, catalysts, and the techniques for monitoring matter at the atomic level, such as STM; computational chemistry, which has been brought to the desktop level, making molecular modeling a powerful technique in designing and understanding molecules and their behavior; macromolecular structures such as polymers and biopolymers, in particular proteins; and new reagents, such as organometallic compounds that can act as templates for molecular synthesis and self-assembly systems that can direct the construction of other molecules.

So Far, Fullerene Studies Dominate Chemical Citations In The 1990s

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