bulky salicylaldimine—an approach developed by Maurice S. Brookhart, chemistry professor at the University of North Carolina, Chapel Hill. The Caltech team synthesized a number of variants. They were able to produce polyethylene with a molecular weight of more than 250,000, narrow molecular weight distribution, and very little branching. They were also able to copolymerize ethylene and olefins functionalized with polar groups such as hydroxyl. 'These are exciting results that represent a significant step forward in our understanding of transition-metal olefin polymerization catalysis," says Tobin J. Marks, chemistry and materials science and engineering professor at Northwestern University, Evanston, 111. "It's impressive work and has meaningful industrial implications," says John J. Murphy, director of metallocene and single-site catalyst programs at Catalyst Group in Spring House, Pa. However, he says, it's not an unanticipated development. "It's a very logical extension of where the technology is going in industry," he says. The Grubbs group is continuing to work on its catalyst family. "It will be interesting to see how this area develops as the scope and mechanism are further explored," Marks notes. Elizabeth Wilson
EPA issues guidelines on planting Bt corn The Environmental Protection Agency has issued new guidelines for growing Bt corn—corn that is genetically modified to contain a gene from the soil microorganism Bacillus thuringiensis, enabling the corn to produce its own insecticide. The measures are designed to protect against the emergence of insects that are resistant to the Bt toxin and to protect monarch butterfly caterpillars and other nontarget organisms. Every cell of Bt corn, including the pollen, produces a specific toxin that kills the European corn borer. Last May, John E. Losey, an entomologist at Cornell University, reported lab research that shows that Bt corn pollen can kill monarch butterfly caterpillars [Nature, 3 9 9 , 214 (1999)]. Since May, environmentalists have been demanding that EPA take steps to protect the monarch butterfly from possible harm from Bt corn pollen. Studies to determine whether Bt corn
pollen harms monarchs in thefieldare so insects. "We strongly advise that [seed producers] provide technical assistance far inconclusive. In its guidelines, EPA says manufac- to the growers to help place refugia [returers and sellers of Bt corn seed must quired plots of non-Bt corn] where they impose certain contractual require- can serve both goals of managing resisments on farmers. If manufacturers tance and minimizing nontarget expodon't, their products, which are up for sure," writes Janet L. Andersen, director reregistration in 2001, won't be reregis- of EPA's Biopesticides & Pollution Pretered. First, at least 20% of their corn- vention Division, in a letter to Monsanfields must be planted in traditional, non- to, a major producer of Bt corn seed. 'The measures commu| nicated by the EPA . . . are I nothing new for us or our £ customers, since most of 1 them were already in ^ place," Monsanto says in a I statement. The company £ has not released any grow< er contracts that would show exactly what it required of growers last year. However, Jane Rissler, senior staff scientist at the Union of Concerned Scientists, contends that "these regulations show EPA is EPA's guidelines won't satisfy protesters such as these taking the resistance matin Washington, D.C. ter and the monarch issue Bt corn. Cornfields in cotton-growing ar- seriously. This shows EPA believes the eas must contain more—50%—non-Bt issue is far from settled." Rebecca J. Goldburg, senior scientist corn, because more than half of the cotton grown in the U.S. is Bt modified. In at the Environmental Defense Fund, addition, EPA is asking seed producers to says these new requirements may level ensure that farmers plant some of this tra- the playing field for the different types ditional corn around the edges of the field of Bt corn. Previously, recommendaor so as to protect monarch caterpillars tions as to the extent of Bt corn refugia and other nontarget organisms from ex- varied from 5 to 20% depending on the exact variety of Bt corn, and they were posure to Bt corn pollen. Furthermore, EPA is demanding that not mandatory, she explains. But, she seed producers expand their monitor- says, the new guidelines are not strong ing activities to provide early warning of enough to protect the monarch. Bette Hileman any potential resistance to Bt toxin by
Monsanto sued for breach of merger contract Delta & Pine Land, the leading U.S. cottonseed producer, is suing Monsanto for failing to complete its 19-month-long attempt to buy the company. The Scott, Miss.-based company is seeking at least $1 billion in compensatory damages as well as punitive damages. The $1.9 billion deal fell apart the day after Monsanto agreed to merge with Pharmacia & Upjohn (C&EN, Jan. 3, page 7). The deal was terminated, Monsanto says, due to continued delays in U.S. government reviews and burdensome demands by the Department of Justice. Delta & Pine Land alleges that Monsanto breached its contractual obligations to use "commercially reasonable ef-
forts to respond fully and promptly to all inquiries ... and to resolve objections by the Antitrust Division of the Department of Justice in seeking regulatory clearance." Monsanto calls the allegations "unreasonable and without merit" and says it will defend itself vigorously. It's already paid Delta & Pine Land an $81 million termination fee under their May 1998 merger agreement (C&EN, Jan. 10, page 8). "It's disappointing that Delta & Pine Land—a technology partner we've worked with for years—would file this suit when they worked side by side with us in attempting to secure regulatory approval of the merger," Monsanto President Hendrik A. Verfaillie comments. JANUARY 24, 2000 C&EN
15
news of the w e e k "For a year and a half, we exercised every reasonable effort and a tremendous amount of time, energy, and money to make this merger happen," he continues. "After numerous attempts to reach an acceptable compromise, we concluded that the Department of Justice's demands made no sense from a business point of view, and that to accept them would place both Monsanto and Delta & Pine Land at an unfair competitive disadvantage in the marketplace." Roger D. Malkin, Delta & Pine Land's chairman and chief executive officer, says the company regrets having to sue, but it had "no other choice in order to protect the interests of our company and our shareholders." He notes that the company is continuing discussions with Monsanto and hopes to achieve a mutually acceptable resolution. Both companies say the lawsuit will not affect the development or commercialization of their genetically engineered crops. Monsanto, meanwhile, is focusing on its pending merger with Pharmacia & Upjohn and the sale of as much as 20% of its agricultural business to the public. Ann Thayer
Bulk silica imprinted with organic functional groups Researchers have devised a new strategy for imprinting bulk microporous silica with organic functional groups that could lead to the design and synthesis of materials with features modeled on those of enzymes and antibodies. Mark E. Davis, professor of chemical engineering at California Institute of Technology, Pasadena, and coworker Alexander Katz, now assistant professor of chemical engineering at the University of California, Berkeley, used molecular imprinting to generate bulk amorphous silica with specially tailored microcavities containing aminopropyl groups covalently attached to the pore walls [Nature, 403, 286 (2000)]. 'This is a very interesting paper, demonstrating successful imprinting and control over the spatial distribution of organic functional groups in an inorganic support material," comments Andreas Stein, assistant professor of chemistry, University of Minnesota, Minneapolis, and an 16 JANUARY 24, 2000 C&EN
Pore walls anchor functional groups CH 2 -0-C-N-(CH 2 ) 3 -Si-R Polymerization , R-Si-(CH 2 ) 3 -N-C-0-H 2 C
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expert on porous inorganic materials (see page 33). "I would expect this work to spawn a lot of new research." Davis and Katz produced bulk amorphous silica by polymerizing tetraethoxysilane using an acid catalyst and a method for synthesizing three-dimensional networks from metal alkoxides known as sol-gel polymerization. During the polymerization process, they incorporated into the silica framework "imprint molecules" consisting of aromatic rings carrying one, two, or three 3-aminopropyltriethoxysilane side groups. Removal of the aromatic cores created framework cavities in which the aminopropyl groups were anchored. They then established the presence of the imprint-generated microporosity by solid-state nuclear magnetic resonance spectroscopy, physical adsorption experiments, catalytic transformations, and other studies. "The novelty and thus the importance of the work is that the experiments show that imprinting is possible in bulk silica," remarks Kay Severin, senior researcher at Ludwig Maximilians University, Munich, Germany, who recently showed that organometallic catalysis can be enhanced by polymer imprinting with a transition-state analog (C&EN, Jan. 10, page 31). 'Traditional-
R = 0CH 2 CH 3
ly, molecular imprinting has been carried out with organic polymers or in some cases on silica surfaces." According to Davis and Katz, their silica-imprinting concept can be extended to other types of chemical functionalities and imprints of different size and shape, thus making it plausible to incorporate more specificity and activity into imprinted sites. "One can now think of using the transition-state analog approach, which is used in the area of catalytic antibodies, to attempt to create rationally designed heterogeneous catalysts," Davis says. "A major breakthrough would be to create a chiral system. To induce chirality, at least three sites of interaction between solid and guest are needed," he explains. That "is why we developed a methodology for at least three functional groups." Katz tells C&EN that his group at UC Berkeley is aiming to develop imprinting as a general strategy for synthesizing materials-by-design. "One of the issues in particular that we wish to pursue is the amount of complexity it is necessary to incorporate into these materials in order to mimic some of the essential features of binding and catalysis found in biological systems," he says. Michael Freemantle
