science/ technology concentrates
Saudin, a complex terpenoid, synthesized
that are produced only by eukaryotes— the alkaloid donates electrons to the elecwere found in shales that are 2.7 billion tron-poor bromine atoms covalently bound years old. The molecular fossils are "the in a highly fluorinated environment.^ oldest preserved biological molecules in the world," Brocks says.^
Crystalline networks, by the numbers
Saudin, a terpenoid with hypoglycemic UV produces moon's activity that's been isolated from the sodium atmosphere Commercially important zeolites and leaves of the toxic plant Cluytia richardimany other interesting compounds are ana in Saudi Arabia, has been synthe- The sodium in the moon's tenuous atmo- made up of crystalline networks in which sized by researchers at the University of sphere appears to be released from the each atom is connected to exactly four Pennsylvania \J. Amer. Chem. Soc, 121,lunar surface by ultraviolet light [Nature, neighbors. Using mathematical tiling the7425 (1999) ]. The key step in the synthe- 400, 642 (1999)]. Scientists have specu- ory, Jacek Klinowski, reader in chemistry sis of the highly oxygenated bisketal lated on the source of the sodium, which at the University of Cambridge, England, (shown) is an intramolecular dioxenone must be replenished continuously as the and coworkers now have counted the photocycloaddition reaction atoms rapidly drift off into space or are re- number of variations of that topology that establishes the critical captured by the surface. Postulated [Nature, 400, 644 (1999)]. They deterstereochemical relation- mechanisms included sputtering of the mined that there are exactly nine differship of the quaternary car- surface by the solar wind, thermal de- ent four-connected networks in which bon centers at C-13 and sorption, or micrometeorite impacts. An each vertex is the same (uninodal) and of C-16. Chemistry pro- experiment devised by physics and the simplest kind and at least 145 more uniN\ fessor Jeffrey D. chemistry professor Theodore E. Madey nodal networks with more complicated - 0 Winkler and cowork- and research associate Boris V. Yakshin- vertices. There are 117 topological types er Elizabeth M. Doher- skiy at Rutgers University, Piscataway, with two distinct simple vertices and 926 ty identified a highly functionalized pho- N.J., indicates the likely scenario: When with three. Most of the uninodal nettosubstrate that would lead to saudin. Af- photons strike the lunar surface—com- works are known, but most of the others ter synthesizing the substrate in 11 steps, posed largely of silicon dioxide—the min- are new. Enumerating the possibilities they produced saudin in four additional eral becomes excited and donates elec- may make synthesis and structural detersteps. Overall yield of saudin was 5%, fol- trons to sodium ions in the surface layer. mination of new materials simpler.^ lowing an average yield of 83% per step.«4 The sodium atoms, now neutral, desorb from the surface. The scientists simulated conditions on the moon by preparing Amines from olefins World's oldest in a vacuum thinfilmsof silicon dioxide and ammonia and depositing sodium on top. They then biological molecules bombarded thefilmswith UV photons, A dual-metal catalyst is the key to the first Earlier this month, Roger E. Summons electrons, or ions. Only the photons liber- efficient hydroaminomethylation reacof the Australian Geological Survey Orga- ated sufficient quantities of sodium to ac- tion using ammonia, claim chemists at nization (AGSO) reported that oxygen- count for the lunar atmosphere, the sci- the University of Rostock, Germany, and at Celanese, Oberhausen, Germany [Anproducing cyanobacteria evolved at least entists say.
