The agencies are monitoring imports, investigating reports of mislabeled products, and looking into falsifications of export and import documents. But illegal CFCs are difficult to track once they get into the stream of commerce. "It's not like a dope case where you walk in, find white powder sitting on the table, and you arrest the person/' says George H. White II, special agent in the Customs Service's Miami office. "These cases are paper intensive. It takes a while to work them up." Pamela Zurer
Molecular wire conducts photonic signal Taking a cue from nature, two chemists at Carnegie Mellon University in Pittsburgh have synthesized a 9-nm-long molecule that absorbs a photon of light at one end, transmits the energy to the other end, and emits a different photon of light. Such a "molecular photonic wire," as its developers call it, might one day be used to transmit signals between molecular-scale devices engaged in information processing, for instance. Although molecular electronics is still only a dream, several groups have been working toward its realization by developing molecular electronic wires that can carry charge (electrons or holes). However, attachment of input and output leads to such wires—known as the "connection problem"—remains a major challenge, says Jonathan S. Lindsey, associate professor of chemistry at Carnegie Mellon. The molecular photonic wire that Lindsey and postdoctoral fellow Richard W. Wagner developed [/. Am. Chem. Soc, 116, 9759 (1994)] does not have a connection problem because the
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ACS spurs National Chemistry Week efforts A special issue of WonderScience—aimed at sparking interest in science among children and parents—and a "Milestones in Chemis- ^. try" calendar, featuring *^^Dfi *·«** important events in chemistry for nearly every day in 1995, are among materials developed by American Chemical Society staff to celebrate National Chemistry Week (NCW), Nov. 6-12. Aimed at communicating chemistry's contributions to society, this will be the fourth fullscale NCW. Observance of NCW began with a single day in 1987, was expanded to a week in 1989, and was made an annual event in 1993. ACS's 187 local sections will conduct exhibits and demonstrations at shopping malls, museums, libraries, and other sites. NCW's national office has distributed more than 1.3 million publications and items to aid local section efforts. And ACS staff has planned a number of projects. For example, on Nov. 7, the ACS Continuing Education Department will offer a live, two-hour satellite TV seminar called "Teaching Chemistry 1994: A Materials Science Anthology"—designed to help educators incorporate materials science concepts into introductory chemistry curricula. On Nov. 10, the ACS Department of Academic Programs will present another TV seminar, this one
signal is sent to and received from the wire using light. Lindsey's inspiration comes from light-harvesting complexes containing chlorophyll that plants use for photosynthesis. These complexes, consisting of hundreds of pigments in a solidstate array, absorb sunlight and quickly convey it to reaction centers, where it is converted into chemical energy.
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aimed at undergraduates and high school students considering chemical industry careers. And on Nov. 6, NCW will be featured, as in past years, in "The Mini-Page," a weekly section for children that appears in some 475 U.S. newspapers, with a total circulation of about 50 million. Linda Ross
Seeking to mimic the process, Lindsey designed a much simpler linear array of five porphyrin-based pigments that absorbs and emits light in solution. Using repetitive coupling methods, Wagner synthesized the photonic wire from three building blocks similar to those in natural photosynthetic lightharvesting complexes. At one end of the wire is a boron-dipyrromethene
Molecular photonic wire is a string of porphyrins
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OCTOBER 31,1994 C&EN
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