ACS MEETING NEWS: Manual for safe
handling, storage, and disposal of chemicals receives a makeover
T
HE WIDELY USED manual of laboratory safety,
“Prudent Practices in the Laboratory: Handling and Disposal of Chemicals,” has been revised for the first time in 16 years by a committee of the National Research Council (NRC). Several committee members presented the updated manual last week at the American Chemical Society national meeting in Anaheim, Calif. “We looked at every page of the previous book and either verified that the information was good or updated it,” one of the meeting speakers, Peter Reinhardt, director of Yale University’s Office of Environmental Health & Safety, told C&EN in a separate interview. The new edition of the book—published by the National Academies, which encompasses NRC—contains updated information on handling, storage, and disposal of hazardous chemicals, as well as guidelines for handling biohazardous or radioactive material, the NRC committee said. Committee members said it also cov-
SINGLE-MOLECULE POTENTIOMETERS ACS MEETING NEWS: Moving electrode changes conductance of single-molecule device
T
HE CONDUCTANCE THROUGH a single-mole-
cule molecular wire can be controlled by changing where an electrode contacts it, chemist Colin P. Nuckolls of Columbia University reported last week at the American Chemical Society national meeting in Anaheim, Calif., and in a recent Nano Letters paper (DOI: 10.1021/nl104411f). The resulting device behaves as a single-molecule potentiometer, a variable resistor that can control electronic devices. Nuckolls, physicist Latha Venkataraman, and their coworkers connected both ends of oligoacetylene molecular wires to gold electrodes and measured the system’s conductance. They found that the conductance through the molecule depends on where the electrode binds to it. The electrodes can contact the molecules at their terminal sulfides or at any point along the conductive conjugated backbone, Nuckolls said. Nuckolls likens the double bonds in the oligoacetylene chain to the rungs of a ladder. Each time the elec-
ers new topics, including nanomaterials, green chemistry, lab security, and lab decommissioning. NRC committee cochair William F. Carroll Jr., vice president of Occidental Chemical and a past-president of ACS, told C&EN that he has one message for chemists about the new edition of the book: “No matter who you are, if you think this book isn’t for you, you’re wrong—it is.” The book is designed to be useful in academic, industrial, and government laboratories, NRC committee members said. Aside from chemistry, they said, the manual also applies to biology, engineering, or other laboratories that handle chemicals. The previous edition was published in 1995 and combined and updated two manuals from the 1980s. The committee for the current update began its work in 2008 and was composed of laboratory safety experts from academia, industry, and government. The book is available to order or view online at the National Academies website, nap.edu/catalog. php?record_id=12654. The update project received funding from the Department of Energy, NSF, and NIH, in addition to several chemical and materials companies, the Howard Hughes Medical Institute, and ACS, which publishes C&EN.—JYLLIAN KEMSLEY
NRC’s Kathryn Hughes (from left), revision committee member Russell Phifer, and Meridian Life Science’s Cynthia Perrine look at the revised manual.
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‘PRUDENT PRACTICES’ UPDATED
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NEWS OF THE WEEK
trode steps past a rung, “it changes the resistance conductance state because you’ve changed the effective length of the molecule you’re measuring through,” he told C&EN. X The Columbia team performed the experiments using a scanning tunneling microscope. When the gold STM tip moves repeatedly toward and away from a gold substrate, it exposes gold atoms on the electrodes where oligoacetylene chains can bind. The tip then steps along and binds at different points along the I conjugated backbone. The system’s conductance NC decreases stepwise as the tip binds the molecular wire farther from the substrate, Nuckolls said. CN “Very often, papers in the molecular electronics community present simplified, idealized diagrams of molecular junctions, showing two sharp metal electrodes bridged neatly by a fully extended molecule, nicely bound at both ends to the apexes of the electrodes,” said Douglas Natelson, a molecular electronics expert at Rice University. “This work X is particularly important because it highlights that this does not have to be the case. Molecules may be contacted asymmetrically, even somewhere in the middle of a long molecule, and contribute in a well-defined way to the overall conductance.” Where an electrode binds—at the In the future, Nuckolls plans to use end of a molecule (as shown here) single-molecule measurements to study or along its backbone—determines the effects of dopants on single-molecule the conductance through a singleelectronics.—CELIA ARNAUD molecule device.
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