November 2002 Meeting
The three hundred and thirty eighth meeting of the Section will be held on Wednesday, November 13 at 8:00 pm at Lycoming College in Williamsport, PA. The guest speaker, Dr. Robert Minard from Penn State University, will present a talk entitled "Studies in Chemical Evolution and the Origin of Life".Directions: From I-80, take Route 15 N (exit 30-B). Travel approximately 15 miles to Williamsport. Continue on 15 N over the Market Street Bridge (stay in the left lane). Follow the sign for the Business District. Go to the third traffic light and make a right on to Little League Blvd. Go 1 block to the stop sign and turn left on to Mulberry Street. Travel to the first traffic light and turn right on to Washington Blvd. The entrance to the parking lot will be on your right.
Dinner: 5:30 pm at the Bullfrog Brewery and Restaurant, 229 W. Fourth Street, Williamsport. Call 570-326-4700 for directions. Dinner will be from the menu. Please call or e-mail your reservations to Laura Printzenhoff (570-321-4180, printz@lycoming.edu) by November 6.
Studies in Chemical Evolution and the Origin of Life
Where did we come from? Are we alone in the Universe? What does the future hold for us? (and perhaps others "out there"?) These are questions that will receive considerable attention in this new millennium as we explore our universe and investigate plausible scenarios for the origin of life on this and other worlds.
Hydrogen cyanide is known to be present in interstellar clouds, comets, and certain planetary or lunar atmospheres. It is also formed in experiments simulating the material composition and energy fluxes thought to exist on the primitive earth and other young planetary systems. Hydrogen cyanide polymers--heterogeneous solids ranging in color from yellow to orange to brown to black-- form spontaneously from HCN and traces of base catalysts and may be among the organic macromolecules most readily formed within the solar system. The observation that these polymers can be degraded to amino acids and nitrogen heterocycles makes it probable that they played an important role in the early stages of chemical evolution. Nevertheless, their full structural characterization has still not been accomplished. A number of mass spectrometric methods have now been applied to this structural problem including FAB-MS, thermal desorption EI-MS, ESI-MS, APCI-MS and off-line TMAH thermochemolysis/GC-MS. This latter method causes bond cleavage and in situ methylation producing a suite of products which provides valuable insight into the substructural features of HCN polymers and serves as a sensitive diagnostic tool for detecting the presence of HCN polymers in samples from diverse sources. From these data, it appears that the polymer has segments containing amino acid precursors such as glycine, alanine, aspartic acid and glutamic acid, and nitrogen herterocycles such as adenine, xanthine, and uracil (Minard et al. 1998). Recent solid state NMR studies confirm the presence of amide linkages in HCN polymer.
In experiments simulating Titan's atmospheric chemistry, Khare et al. (1984) have reported the production of solids - Titan tholins - whose observed spectral properties closely match those of this satellite's orange aerosol haze. Analysis of these solids by TMAH thermochemolysis/GC-MS reveals a large number of degradation products matching those derived from analysis of HCN polymers by this same method (Minard et al. 1999). These results provide evidence that N2/CH4 tholins contain HCN polymers, which could thus be major components of Titan's atmosphere.
Much more research needs to be done in order to obtain definitive structural details, a mechanism of formation, and the full scope of reactions of these complex, heterogeneous HCN polymers. The conjecture that these polymers may have been the original biopolymer, with self-replicating capabilities, makes this puzzle all the more exciting to solve.
Dr. Robert Minard is Senior Lecturer in Chemistry and Director of the Organic Chemistry Labs at the Pennsylvania State University. His research involves application of instrumental methods, particularly gas and liquid chromatography, mass spectrometry, and NMR, to problems involving chemical evolution and the origin of life, marine chemistry and biopolymer/macromolecular analysis. Dr. Minard holds a bachelors degree in chemistry from St. Olaf College and a Ph.D. in organic chemistry from the University of Wisconsin.
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