SCIENCE & TECHNOLOGY
DALTON CROSSES THE POND European inorganic chemistry meeting comes to Berkeley to showcase MAIN-GROUP CHEMISTRY ELIZABETH K. WILSON, C&EN WEST COAST NEWS BUREAU
THE DALTON DISCUSSIONS, venerable,
After the presentations come conversations. Attendees sit together, and the discussion centers around chemistry as a whole, rather than just one talk, Arnold says. “It’s like being back in graduate school and having a group meeting,” says Frances H. Stephens, a chemist at Los Alamos National Laboratory who presented a poster at the meeting. “It is very interactive, and you have a lot of time to talk to people about the intricacies of their research.”
DD11 built upon the foundation laid by a large main-group chemistry sympointimate yearly conferences focusing on sium held at the 2004 American Chemical inorganic chemistry and sponsored by the HYDROGEN STORAGE materials (C&EN, Society meeting in Anaheim, Calif., in Royal Society of Chemistry (RSC), have Jan. 28, page 67) generated a lot of buzz honor of the 70th birthday of University always been held in Europe. at the meeting, as did silicon nanowires of Texas, Austin, chemistry professor Not this year. The 11th Dalton Discus(C&EN, Jan. 14, page 12) and polymers and modern main-group chemistry piosions (DD11) for the first time ventured (C&EN, Aug. 6, 2007, page 9). neer Alan H. Cowley (C&EN, May 10, across the pond, all the way to the UniverFrom the German labs of University of 2004, page 39). Since then, the field has sity of California, Berkeley, to highlight Regensburg chemistry professor Manfred continued to burgeon, particularly in arthe renewed and invigorated field of mainScheer (C&EN, Oct. 22, 2007, page 48) and eas such as materials chemistry, hydrogen group chemistry. University of Karlsruhe chemistry professtorage, polymers, and nanowires, Arnold Main-group chemistry, that broad subsors Hansgeorg Schnoeckel and Andreas says. field of inorganic chemistry that includes Schnepf came reports of new metalloid The unusual format of the Dalton Disgroups 1, 2, and 13 to 18 on the periodic taclusters. “The complexity of these molcussions allows intense interactions that ble, was once considered rather dry. Tradiecules is really unprecedented,” Arnold are not always possible in a typical meeting, tionally, when people heard of main-group says. chemistry, “they thought of very old chemistry,” says John Arnold, a chemistry professor at UC Berkeley. Mes – – – – Mes Mes Mes What would come to mind F F F F B Hg B Hg B Hg – B B B are staid compounds that Mes Mes Mes F Mes Mes Mes weren’t considered to be very Mes Mes reactive, such as cements and silicates. But that’s no longer the Mes = mesityl picture. Main-group chemistry is experiencing an ongoFLUORIDE TRAPPERS A chelator Ph Ph Mes Mes ing renaissance as chemists complex from Gabbaï’s lab features Me Me devise syntheses of ever F Mes B + P Mes B P both boron and mercury as binding sites F– more elaborate molecules Ph Ph for fluoride ions (top). A phosphonium/ with atoms such as boron, borane Lewis acid also has a strong fluorine, mercury, and tin affinity for fluoride (bottom). that have exotic bonding Ph = phenyl, Mes = mesityl, Me = methyl characteristics and intricate structures. participants say. The format is modeled “The message of this meeting is there is Boron, which is similar to carbon yet after that of another RSC meeting, the lot of very interesting new chemistry aselectron deficient, continues to play a Faraday Discussions, which focus on physisociated with main-group elements,” says prominent role in main-group chemistry. cal chemistry. Arnold, a coorganizer of the conference. For example, Frieder Jäkle, chemistry Rather than a series of moderate-sized UC Berkeley, the UC system’s flagship professor at Rutgers University, described talks, each Dalton Discussions session campus, seemed a natural locale choice compounds that contain two boron atleads off with a keynote speaker, followed for the meeting organizers because of the oms that form a rigid bridge between two by three or four very short presentations. university’s “large community of synthetic ferrocene groups. His team varied the To bring participants up to speed on each chemists who work in the area of mainproperties of these complexes by changothers’ work even before the meeting congroup chemistry,” says Rebecca Quine, ing constituents on the bridge. By placing venes, all of the talks are prepublished in a manager of conference promotions and electron-withdrawing groups on the boron, special issue of Dalton Transactions. logistics for RSC. for instance, Jäkle reported that he could WWW.C E N- ONLI NE .ORG
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POSTER S ESS ION
ACS Inorganic Division Adds U.S. Touch To Dalton Discussions
PAU L O’ BR I EN
boranes for hydrogen storage of their work, using only one ligand complexes as building won the Best Young InvesPowerPoint slide. blocks in supramolecular cotigator Award. She says the “This was a way to give ordination compounds. strategy was useful for her teasers for a lot of posters,” Other poster winners inown poster-visiting planning. says John Arnold, a chemiscluded Joshua Bates of the University of British Columbia; Vivienne Blackstone of the University of Bristol, in England; Stefan Minasian of the University of California, Berkeley; and Michael Huber of the UniversiPOSTER POSTERITY Dalton Transactions Editor Jamie Humphrey (left) gathers ty of Karlsruhe, with poster organizers and winners (from left) Gabbaï, Minasian, Arnold, Bates, in Germany. Stephens, Huber, Blackstone, and Dielmann. Because “Being a busy person, I have try professor at UC Berkeley it’s often difficult to decide only so much time to read the and one of the meeting’s which posters to visit during abstract book,” she says. organizers. a session, Gabbaï also experiBesides, mastering the “It was pretty effective,” mented with a new format, sound bite can be an imporsays Frances H. Stephens, a which he had seen previtant skill for young scientists, Los Alamos National Laboraously at Gordon Research Stephens says. “Presenting tory chemist who gave one Conferences. Conference one’s research in a condensed of the “flash” presentations. attendees gathered while 15 way is probably a really good Stephens’ poster on the deto 20 poster presenters each learning experience.” velopment of liquid amine gave a one-minute summary
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The Royal Society of Chemistry’s traditionally Europebased inorganic chemistry meeting, Dalton Discussions, had a nontraditional U.S. locale this year. It also featured some extra U.S. flavor with help from the American Chemical Society Division of Inorganic Chemistry, which funded the meeting’s poster presentations. Texas A&M University chemistry professor François P. Gabbaï organized the session of some 60 posters. His tasks included obtaining travel grants for students and prize money for a contest. Fabian Dielmann, a graduate student in the lab of Manfred Scheer at the University of Regensburg, Germany, won a contest for best poster by a grad student or postdoctoral fellow for his presentation on the synthesis of phosphorus ligand complexes with extended phosphorus frameworks. The poster also showed how Scheer used the phosphorus
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A GROUP led by François P. Gabbaï, a chemistry professor at Texas A&M University who organized the meeting’s poster session with sponsorship from the ACS Division of Inorganic Chemistry, is designing boron-based receptors that bind with fluorine ions that might also be eventually developed for use in fluoride sensors.
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IRON AND BORON WORKER A diboradiferrocene from Jäkle’s lab has tunable electronic Ar properties that B change with
Fe
the groups B attached Fe Ar to the boron atoms Ar = aryl (phenyl, mesityl, or pentafluorophenyl).
In one of his research projects, Gabbaï is working on chelators that rely on two binding sites to grab a target atom. One of Gabbaï’s strategies employs electron-deficient boron as one binding site and mercury as the other. Despite mercury’s potential toxicity, Gabbaï says, its complexes are stable and compatible with water, and their penchant for phosphorescing at room temperature makes them good candidates for fluoride sensors. RSC has DD12 in the works, and the organization says it is looking at possibly holding future meetings, including Faraday Discussions, in the U.S., Quine says. “The discussion format, especially, is something that American audiences warm to,” she observes. ■ WWW.C E N- ONLI NE .ORG
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increase interactions between the ferrocene moieties. The molecules have numerous potential uses, Jäkle says. Ferrocenes, in addition to being very rigid—which allows them to preserve the complex’s geometry—can be reversibly oxidized. Oxidizing and reducing the ferrocene groups changes the shape of the molecules, making them potentially useful as molecular machines or actuators. And boron’s ability to bind substrates could make the compounds potentially useful for Lewis acid catalysis and for sensing anions such as fluoride, an anticavity additive in drinking water and toothpaste that could be toxic in large quantities.
