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French group prepares copper complexes that resemble "inside-out" DNA Copper complexes that mimic the elegant double-helical structure of DNA but turn the structure insideout have been prepared for the first time by chemists at Louis Pasteur University in Strasbourg, France. The new molecules, while not themselves DNA, may enable scientists to gain insights into how it interacts with other molecules. Such studies could eventually lead to the development of new drugs that target DNA. The new molecules, prepared by professor Jean-Marie Lehn and coworkers Ulrich Koert and Margaret M. Harding, consist of an organic "spiral staircase" curling around a column of three or five copper ions. The staircase is fashioned from two intertwined strands of a linear oligomer containing bipyridine units. Attached to each bipyridine unit and flaring outward is a pair of deoxynucleosides, such as deoxythymidine. In DNA, the deoxynucleosides are inside the double helix and stacking interactions between them hold the two strands together. The overall charge of DNA is negative. In Lehn's molecules, by contrast, the deoxynucleosides are outside the helix and the stacking is between pyridines. The overall charge, due to the copper ions, is positive. The structure of these so-called nucleohelicates is "strikingly reminiscent of Linus Pauling's original proposal for the structure of DNA," notes coordination chemist Edwin C. Constable of the University of Cambridge, U.K. That proposal, which was later shown to be incorrect, put the deoxynucleosides on the outside and the charged phosphate groups facing in. Remarkably, the nucleohelicates assemble spontaneously when the bipyridine chains are allowed to interact with copper ions. Scientists aren't sure what drives this spontaneous assembly, although Constable thinks an important controlling factor is the stacking of coplanar pyridine rings. Lehn has been studying such selfassembling helicates for years, but the new twist is the addition of nu-
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cleoside appendages. He says other groups can also be attached to the helix, such as amino acids, sugars, and electroactive and photoactive Q . units. ;V>VAN' Lehn's compounds H > * ,0 + may help shed light on \ OR i (cu ) r u RO ^\ N H the ways biological molecules are built up and )Ho how they recognize and HN/> RO interact with other molecules, Constable says. Lehn's octathymidino-trihelicate In particular, the nucleoterf-butyldimethylsilyl helicates might be used to probe a new type of molecular recognition— Double-helical complexes, which "the recognition of one helix for another helix," he tells C&EN. They are being studied by several other "might intercalate or enter into tri- groups as well, might also be enviple-helix hydrogen-bonding inter- sioned as a model for a molecular actions with DNA," he notes in a wire, Constable observes. Extended companion article to Lehn's paper in indefinitely, the complex essentially last week's issue of Nature [346, 339 would be a metallic filament en(1990)]. In addition, double-helical cased inside an organic insulator. At complexes with photoactive metal least that's "the way I think about it centers might be developed to target in grant proposals," Constable specific nucleic acid sequences on laughs. DNA, he says. Ron Dagani
Chemical industry in China on rebound After hobbling through what one Chinese publication calls "a rough and turbulent time" last year and early this year, China's economy and industry and its foreign business ties show signs of bottoming out, according to official figures just issued. However, Chinese and U.S. sources caution, many serious problems remain. Overall industrial output has started up, with monthly growth rates of 1.4, 2.0, 4.2, and 5.9% in March through June, compared with 1989, and 2.2% growth for the first half of 1990. This follows declines starting last October—down 0.9% in January and February, for example. Afflicted by an austerity program, major infrastructure deficiencies, and world reaction to the political crackdown that began in Beijing's Tiananmen Square on June 4, 1989, China's industrial output grew just
6.8% in 1989, only a third of the 1988 rate (C&EN, Feb. 19, page 6). Chemical industry led the rebound with a 6.5% increase in the first half, three times higher than industry overall, after also stagnating in January and February. Reflecting the top priority China gives agriculture, fertilizer and pesticides made the most dramatic leaps. China produced 45.9 million metric tons (gross weight) of chemical fertilizer in the first half, up 8.4% from last year's first half, and 119,000 metric tons of pesticides, up 16%, exceeding plan targets by 2.7% and 6.7%, respectively. Of 16 major chemicals, 14 fulfilled their half-year goals. Foreign investment also rose in May and June, following a decline in the second half of 1989 and through April this year. China approved 530 foreign-funded projects in May with promised foreign capital of $540 milJuly 30, 1990 C&EN
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News of the Week lion, up 47% from May 1989. Last month, it approved 644 such projects with promised foreign capital of $576 million, up 24%. Comparisons are not skewed, the Chinese say, because last year's turmoil did not affect foreign investment until July and August. Moreover, in the offing is a $5.6 billion loan package from Japan for 1990-95, which will fund 42 projects, including fertilizer plants. Several U.S. chemically related firms are starting or expanding joint ventures. For example, Pfizer is building a joint-venture pharmaceutical plant at Dalian to start up in mid-1992, notes George Suter, vice president for operations at Pfizer International. "After June 4, we reassessed the investment, but we decided to go ahead/'
However, for first-half 1990, foreign investment still trailed that in 1989, with 2784 approved projects (8.2% fewer), entailing $2.35 billion in foreign capital (down 22%). Most projects are export-oriented, mainly in the priority areas of textiles, petrochemicals, machinery, and electronics. Moreover, say analysts at the U.S.China Business Council, ties with China are still far from "business as usual." Political uncertainty and economic problems remain. Analysts expect several Fortune 500 firms to announce sizable projects in the next few months. But in general, they say, deals will be fewer, scaled back in size, and go slower than before June 1989. Richard Seltzer
Chemical industry apparently has much soul-searching to do about improving cooperation between management and labor to prevent catastrophic explosions in its facilities. That message rang clearly last week at a House hearing on Arco Chemical's July 5 explosion of its Channelview, Tex., petrochemical plant that killed 17 workers. The House Government Operations Subcommittee on Employment & Housing, chaired by Rep. Tom Lantos (D.-Calif.), gained no new insights on the cause of the accident, which is being investigated by federal, state, and Arco teams. What did feature in the hearing was the testimony of persons who were next of kin to two deceased workers. The first, Sandra Davis, said her husband The one person killed in the initial often spoke about inadequate trainexplosion was approaching a fire ing and excessive overtime work by door when it blew off its hinges fellow contract workers who were from the force of the blast, he adds. employees of Austin Industries. The Cincinnati's Occupational Safety other, Bernard Blackstock, said his & Health Administration area direc- son, an Arco employee, disclosed to tor, William Murphy, says all indica- him the need to submit safety rules tions are that the flammable sub- anonymously for fear of retribution stance causing the explosion came by plant managers. Both families are from resin reactor number six. But suing the companies for gross negliOSHA is not yet ready to confirm gence. "I just don't understand, with all the fire department's explanation of the effort we put into communicathe explosion. Contract workers—at issue as fac- tion at Arco, why such a thing tors in recent chemical accidents— would happen," testified Arco chairwere not involved in the BASF ex- man Harold A. Sorgenti. "And I'm plosion. According to a BASF certainly going to look into it." He spokesman, the only contract work- said families of each of the 17 workers present at the site that day were ers who died have been given doing repair work on the front of $250,000 in immediate compensathe building. The International tion, and that a hot line will be Chemical Workers Union, which opened to his office for workers to represents all the workers at the use. But he defended Arco's use of plant, is conducting its own investi- contract workers and the record of Austin Industries. An Austin emgation of the explosion. It is too early to estimate mone- ployee, Jack Maywald, also defendtary damages either to the plant or ed Austin's safety and training practo homes, cars, and facilities in the tices at the hearing. Another witness testifying at the surrounding neighborhood, says the BASF spokesman. Fire chief Miller hearing was Robert Dostal of the says most of the damage outside the Chemical Manufacturers Associaplant affected the city of Norwood tion. Dostal defended industry's use across the railroad tracks at the rear of such workers, but also agreed of the BASF plant, the area of the with Lantos that contractor safety isplant where the exploded reactor sues were a problem in search of a solution. was located. Wil Lepkowski Marc Reisch
BASF plant explosion kills one, injures 71 An explosion in a reaction vessel at BASF's resins plant in Cincinnati on July 19 left one person dead and 71 others injured. The BASF facility manufactures acrylic, alkyd, epoxy, and phenol-formaldehyde resins used a$ can and paper-cup liner coatings. At least seven or eight employees remain in the hospital, three in critical condition, says a BASF spokesman. Cincinnati fire chief William A. Miller believes the explosion occurred when a flammable solvent used to clean a reaction vessel vented into the plant and ignited. It is unclear, he says, whether human or mechanical failure was to blame. But the cleaning solvent was not properly vented to a condenser and separator, he adds, and as a result a pressure seal blew, filling the 80-year-old building with a white vapor cloud. Although several other boilers operated in the immediate area, investigators have not yet determined the source of ignition, notes the chief. "I have never seen such complete destruction of a complex in my life," Miller says. Although most people in the plant, which employs 200, were able to get out on their own, fire personnel had to extract some people using a ladder truck because walls and ceilings collapsed, strewing people, along with debris, "all over the place," Miller continues. S July 30, 1990 C&EN
Contract worker use backed at Arco hearing
