My group is currently investigating associative ionization electron imaging spectroscopy using the imaging technique. The experimental set-up consists of three lasers: an excimer and two Nd:YAG lasers. The excimer first dissociates a precursor molecule containing an H atom to yield a free ground state H atom. Next, the two Nd:YAG lasers simultaneously hit the molecular beam and, using REMPE (resonance-enhanced multi-photon excitation), the dissociated H atoms are brought up to a high rydberg state (a high energy state such as n=100). These excited H atoms collide with target molecules and result in associative ionization creating cations that are hard to prepare by any other means. The electrons emitted in the collision land on a 2-D detector and their positions are recorded. After enough electrons hit the detector, an image emerges that reveals the translational energy distribution used to deduce vibrational and rotational characteristics of the cations. The goal of this project is to accomplish two experiments creating both CH5+ and HeH+ in order to study their spectroscopic properties and the associative ionization dynamics. If our experiments are successful we will be able to compare theoretical predictions with experimental data.

This research was funded by NSF Grant CHE-0139256.

The Synthesis of Amine-Triphenolate and Amine-Trithiolphenolate Ligands
Maximillian Bailor, Grinnell College; Chris Oliveri and Stephen Koch, Department of Chemistry, Stony Brook University

It has been shown by Cutler et al. (Nuclear Medicine and Biology, Vol. 26, pp. 305,1999) that amine-trithiolphenolate ligands when combined with gallium (III) or indium (III) are useful in providing a means for brain and myocardial uptake. Needless to say, further interest has arisen in other analogs of amine-trithiolphenolates which may serve as potential candidates for brain imaging agents. To this end, we have been attempting to synthesize various amine-trithiolphenolate compounds beginning with their corresponding phenol components. Using various substituted 2,4-dialkylphenols, we have been synthesizing the corresponding amine-triphenolate in one step by way of a mannich reaction. The product is then allowed to undergo a simple conversion of its hydroxyl to a thiolcarbamate, which after a simple hydrolysis can readily be converted to the desired thiol. Currently, work is being done to convert 2-(hydroxyl-3,5-dimethylbenzyl)amine (NO3') into its corresponding 2-(N,N-dimethylthiocarbamate-3,5-dimethlybenzyl)amine, while progress on the corresponding 2-(hydroxyl-3,5-di-tert-butylbenzyl)amine (NO3") has been slowed due to difficulties in synthesizing the amine compound. The reaction for the formation of the NO3" would seem to show a preference for the product 3-(2-hydroxy-3,5-di-tert-butylbenzyl)-6,8-di-tert-butyl-3,4-dihydro-2H-1,3-benzoxazine; however, progress has been made to avoid formation of this benzoxazine ring. Currently, research on NO3" is focused on converting the now easily synthesized secondary amine into its desired tertiary form. Progress is also readily being made with a third amine-triphenolate: 2-(hydroxyl-5-ethyldibenzyl)amine (NO3"') - which has nearly been synthsized. This research was funded by NSF Grant CHE-0139256.

Derivatization of Single-Walled Carbon Nanotubes Using a Functionalized Organic Crown Ether
Mark Cheng and Stanislaus S. Wong, Department of Chemistry, Stony Brook University

In recent years, intensive study on single-walled carbon nanotubes (SWNTs) has been conducted to gain insight into its unique structure-dependent mechanical, electrical and electromechanical properties. , The chemical functionalization of SWNTs is an important area of research because it enhances the solubility of the tubes to allow for photophysical analysis of the SWNTs to be conducted in order to understand the properties of the SWNTs. Moreover, it allows for molecular devices to be developed. So far, SWNTs have been fluorinated4 by means of reaction with elemental fluorine; derivatized in organic solutions with thionychloride and octadecylamine , as well as with chlorine through the use of dichlororcarbene; ultrasonicated in monochlorobenzene solutions of poly(methyl metacrylate); and noncovalently functionalized using a bifunctional molecule, 1-pyrenebutanoic acid, succinimidyl ester to form amide bonds for protein immobilization. In addition, Michael G. C. Kahn, Sarbajit Banerjee and Stanislaus S. Wong have recently achieved functionalization of SWNTs using organic crown ethers. The previous work completed produced a yield of functionalized SWNT-CE adduct of approximately 10mg. The work completed this summer employed a modified procedure used by Kahn and co-workers to produce a higher yield of the same SWNT-CE. It is an intrinsically difficult problem to scale up nanotube functionalization. This research was funded by NSF Grant CHE-0139256.

Synthetic Studies Towards the Total Synthesis of SNF 4435 C and SNF 4435 D
Elizabeth A. Clizbe, Baldwin-Wallace College; Yeon-Hee Lim and Kathlyn A. Parker, Department of Chemistry, Stony Brook University

SNF 4435 C and D were recently discovered in a cultured strain of Streptomyces spectabilis, a gram-positive soil microbe collected in 2001 in Okinawa, Japan. The SNF compounds were shown to have potential immunosuppressive activity in vitro. They were also shown to reverse multidrug resistance in tumor cells, making them potentially useful in anticancer therapy. These two compounds are stereoisomeric natural products that contain five stereocenters. Their skeletons are based on a nitrophenyl substituted bicyclo[4.2.0]octadiene system containing a spiro-fused tetrahydrofuran ring and g-pyrone ring moiety, which is unique among natural products. SNF 4435 C and D are most likely diastereomers in which a single stereocenter (C-6) has the same absolute stereochemistry and the other four are inverted. The absolute stereochemistry of SNF C and D are assigned as indicated by Figure 1. The hypothesized biosynthesis of the SNF compounds involves conrotatory 8p-electrocylization to produce the cyclooctatrienes with some induction provided by the stereocenter on the tetrahydrofuran ring (C-6). A stereoselective disrotatory 6p-electrocylization proceeds resulting in SNF 4435 C and D.

A four step synthesis starting with p-nitrobenzaldehyde and 2-(triphenylphosphoranylidene)- propionaldehyde through a Wittig reaction has resulted in a,b-unsaturated (E)-vinylaldehyde, followed by the Stork-Zhao olefination in order to generate a trisubstituted (E, Z)-diene, one of the building blocks for the SNF compounds. For the other analogue, a six step synthesis starting with p-nitrobenzaldehyde and Still-Gennari reagent has resulted in a,b-unsaturated (Z)-vinylester, followed by reduction with diisopropylaluminum hydride (DiBAL-H) and oxidation with manganese dioxide (MnO2) in order to afford a,b-unsaturated (Z)-vinylaldehyde. Then, the Stork-Zhao olefination was employed again to generate (Z, Z)-diene.

For the model system of g-pyrone moiety in the other building block, cyclohexanemethanol was tosylated with p-toluenesulfonyl chloride and followed by alkylation with diethyl malonate. One of the ester groups in alkylated diethyl malonate will be decarboxylated and the other ester will react with 2-methyl-3-oxo-pentanoic acid ethyl ester, which was generated from the dianion reaction, to produce the corresponding diketoester. The cyclization of diketoester by using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in benzene with heating will lead to a-pyrone moiety. Methylation of a-pyrone with methyl fluorosulfonate will undergo the desired isomerization to methoxy g-pyrone. This research was funded by the National Science Foundation REU Grant (CHE-0139256).

Synthesis of Norbornyl Fertilinß Polymers as Probes of Sperm-Egg Interactions
Nicole D. Facompre, Lehigh University; Kenny S. Roberts, and Nicole S. Sampson, Department of Chemistry, Stony Brook University

Fertilinß and cyritestin are ADAM (a disintegrin and a metalloprotease) proteins located on the surface of the sperm membrane. Their disintegrin domains mediate sperm-egg binding in mammalian fertilization. Mutagenesis studies in mice have shown that the ECD consensus sequence of the disintegrin loop of fertilinß is important for sperm-egg adhesion. In cyritestin the consensus sequence is QCD. Peptide mimics that contain the binding sequence of fertilinß or cyritestin inhibit sperm-egg binding and fusion in vitro. Linear peptide monomers are only modest inhibitors of fertilization in vitro. The approach of this project is to synthesize multivalent peptide mimics containing truncated binding sequences from fertilinß and cyritestin. Multivalent ligand interactions are stronger than their monovalent counterparts. The ligand-receptor interaction in this approach may also give insight as to the affinity of the multivalent ligands. We synthesized peptide monomers with the sequences ECD (found in the binding sequence of fertilinß), ESA (a fertilinß mutant peptide), and QCD (a truncated version of the binding sequence of cyritestin) for use in ring opening metathesis polymerization (ROMP). To synthesize the peptide norbornyl monomers, we used solution phase peptide chemistry, enabling us to synthesize large quantities of peptide in its protected form. We carried out the amino acid couplings under argon, in dry dichloromethane, with 2-(1H-Benzotriazol-1-yl)-1,1,3,3-Tetramethyluronium Tetrafluorobate/1-Hydroxybenzotriazole and Diisopropylethylamine. The amino termini of the peptides were protected with Cbz, unless cysteine was present in the peptide, in which case Fmoc was used. Cbz-protected peptides were deprotected by catalytic hydrogenation and Fmoc-protected peptides were deprotected by treatment with octanethiol and a catalytic amount of 1,8,Diazabicyclo[5,4,0]undec-7-ene. We purified the peptides after each coupling step in order to obtain pure material for polymerization. The peptide monomers were coupled to norbornene and polymerized by ROMP. A more active catalyst (Grubbs 3rd Generation bispyridine complex) was synthesized from the N-heterocyclic carbene [(H2IMeS)(PCy3) (Cl)2Ru=CHPh] and was used to synthesize peptide oligomers of 10 and 100mers. Future in vitro fertilization assays in mice will monitor the effect of these norbornyl fertilinß peptides on in vitro fertilization. Studying these effects may provide a better understanding of cell adhesion at the molecular level, as well as insight to the causes of certain types of infertility. This work was supported by a grant form the National Institute of Child Health and Human Development (HD38519) and by NSF Grant CHE-0139256.

Investigating the Initial Steps in the Biosynthesis of Menaquinone
Michelle Ferguson and Jacque Zwahlen, Department of Chemistry, Stony Brook University

Tuberculosis kills more than two million people each year and due to the emergence of multi-drug resistant strains of M. tuberculosis new drug targets are required. An ideal drug target is menaquinone, which is the bacteria's sole quinone involved in respiration. In order to investigate menaquinone biosynthesis, the first three enzymes of the pathway were cloned and expressed. Chorismate, a critical metabolite, is the starting point of the pathway. M. tuberculosis has two isochorismate synthases EntC and MbtI. EntC is thought to be the first enzyme of the pathway, while MbtI catalyzes the identical reaction as part of the biosynthesis of the virulence factor, mycobactin. A comparison of these enzymes from different pathways catalyzing identical reactions will be interesting. The previously cloned M. tuberculosis genes MenD, MenC, EntC and MbtI were expressed in various E. coli cell lines. MbtI was the only enzyme to result in soluble protein. Optimization of expression of the other proteins is ongoing. Currently, EntC and MenD have been recloned into Novagen's pET43.1B vector containing a Nus-Tag to increase protein solubility. In addition the E. coli MenF and MenD homologues are being cloned as model systems. Assays for these enzymes have been proposed and involve both HPLC and UV based methods. In addition E. coli EntB has been cloned and purified for use in MenF, EntC and MbtI assays. This research has been funded by NSF Grant CHE-0139256.

Synthesis of Nanoscale Wires for Molecular Computing
Heidi Hsieh and Andreas Mayr, Department of Chemistry, Stony Brook University

Molecular computing utilizes molecular components in lieu of traditional electronic features. This field was developed due to the necessity to create smaller and faster computers. A type of molecular component favored by research groups in molecular electronics is oligo phenyleneethynylenes (OPE) due to their electron transport properties and extended linear shape.

The Stony Brook Moletronics group utilizes OPEs containing strong central electron acceptor groups. These electron acceptor groups behave as single electron islands. Previous efforts in synthesizing these linear molecules, similar to compound 1 shown below, was accomplished by adding phenyleneethynylene units to a center group in a step-wise manner. This approach suffered from diminishing yields with increasing length of the linear molecule. In this study, we developed a flexible procedure, where phenylene and ethynylene groups are added to both the center and end pieces. This efficient synthesis can control the length of the structures by melding small building blocks (4-8) to form intermediate-sized components (2 and 3) which are then combined to yield the final compounds 1. This procedure also allows for the convenient introduction of different terminal groups and electron accepter center pieces. This series of nanomolecules all possess essentially the same electrical properties despite differences in their length. As a result, these nanowires can bridge gaps of varying distances between two electrodes on a nanoscale computer chip. Research was funded by the National Science Foundation's Research Experience for Undergraduates at SUNY Stony Brook.

Computational Analysis of Triclosan as a Lead Compound in Anti-tuberculosis Drug Discovery
Patrice Leahy, Beloit College; and Carlos Simmerling, Department of Chemistry, Stony Brook University

It has been estimated that one third of the world's population are infected with Mycobacterium tuberculosis, the organism that causes tuberculosis. 10% of these people develop active infections and more than two million people die annually as a result. Tuberculosis is presently treated with isoniazid and rifampicin. These drugs act on the enzyme InhA, the enoyl reductase in the fatty acid biosynthesis pathway that is important for the survival of mycobacteria. A recent pressing concern has been the emergence of multi-drug-resistant tuberculosis (MDRTB). This presents a demand for new lead compounds to counteract these resistant strains. In this study we are using computational methods to investigate triclosan, an antibacterial additive in consumer products, as a lead compound for the inhibition of InhA enzyme. Triclosan is a less powerful inhibitor of InhA, the enoyl reductase in tuberculosis, than it is of FabI, the enoyl reductase in E. Coli. Molecular dynamics simulations were performed with the AMBER program on a fragment of InhA:NAD+:triclosan ternary complex including all atoms within 15Å of triclosan in order to examine the interactions of triclosan in the InhA complex. This information can then be used to explain the reduced binding affinity of triclosan for Inha so that the triclosan complex can be modified accordingly. Stipend support for this study was provided by a NSF funded Summer REU Chemistry Internship at Stony Brook University.

Synthesis of water-soluble chitosan by grafting of poly (ethylene glycol) for biomedical applications
Alexander Lodge and Kwansok Kim, Department of Chemistry, Stony Brook University

Chitosan, a functional and linear polysaccharide, is the second most abundant natural polysaccharide (the most abundant being cellulose). This polysaccharide is found in places such as crustacean shells and insect exoskeletons. Due to chitosan's biocompatibility, biodegradability, and biological activity it has been widely used for biomedical applications. However, chitosan's rigid crystalline structure prevents it from dissolving in organic solvents due to intra- and inter-molecular hydrogen bonds. In order to improve chitosan's poor solubility, hydrophilic poly (ethylene glycol) (PEG), was grafted onto the glucosamines of chitosan. PEG is a biocompatible polymer and will act as a hydrophilic modifier without altering chitosan's fundamental features. In our study, a series of PEG grafted chitosan (PEG-g-chitosan) was synthesized and used for biomedical applications such as carriers for drug and gene delivery. PEG-monoaldehyde was prepared by the oxidation of PEG with dimethyl sulfoxide (DMSO)/acetic anhydride. The yield of PEG-monoaldehyde is ~70%. PEG-monoaldehyde was then reacted with glucosamines of chitosan to form an Schiff-base. Finally, PEG-g-chitosan was obtained from the reduction process of the Schiff-base. The yield of PEG-g-chitosan is >80%. The solubility of PEG-g-chitosan was mainly dependent upon the degree of PEG substitution and the molecular weight of PEG. This research was supported by NSF and the Chemistry REU program at the State University of New York at Stony Brook.

Using autoinduction media, ZYP- 5052, to express pantothenate kinase, phosphopantetheine adenylyltransferase, and dephospho CoA kinase
Yun-An Tseng and Dale G. Drueckhammer, Department of Chemistry, Stony Brook University

This project is designed to express the enzymes, pantothenate kinase (PanK), phosphopantetheine adenylyltransferase (PPAT), and dephospho CoA kinase (DPCK) by using autoinduction media called ZYP-5052. These three enzymes from the CoA biosynthetic pathway are needed in large quantities for the synthesis of analogues of CoA. Expression plasmids for each of these three enzymes were transformed into E. coli and the resulting E. coli were grown in ZYP-5052 media. With the autoinduction media, one does not have to monitor the growth and add an inducer at a specific time. The E. coli cells were harvested and lysed and the enzymes were purified by column chromatography. Standard spectrophotometric assays were used to determine the activity of each enzyme. The results showed that both PanK and PPAT were expressed successfully by ZYP-5052. Their activities were 566 units and 1028 units, respectively. For DPCK, the activity was not as high as we expected, but 12.25 units. SDS polyacrylamide gel electrophoresis was used to access the purity of the three enzymes. This study was supported by NSF undergraduate REU grant CHE-0139256.

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