232
National ACS Meeting
San
Francisco, September 10-14, 2006
Temple
University Presentations
Temple
University, 1901 N.13th Street, Philadelphia,
PA 19122
SUNDAY
8:00
AM-12:00 PM, Grand Hyatt -- Bayview; .
Frontiers
in Molecular Biophysical Dynamics: Experiment
and Theory
9:00
a.m. PHYS 33 Spiridoula
Matsika
and Kurt Kistler. Dept. of Chemistry.
Two-
and three-state conical intersections involved
in the photophysical properties of pyrimidine
bases .
Conical
intersections between two and three states of
the same symmetry have been found to play a key
role in nonadiabatic processes. Here we present
studies where the importance of conical intersections
is being investigated in photoinitiated processes
of biologically relevant systems, and particularly
the nucleobases and their analogs. We investigate
the excited states of the pyrimidine nucleobases
and compare them with other pyrimidine molecules
that fluoresce in an effort to understand the
underlying mechanism and cause of the different
S1 deactivation patterns. Large scale ab initio
multireference configuration interaction methods
(MRCI) are being used. Our results show the presence
of many seams of two- or three-state conical intersections
that can complicate the potential energy surfaces
and dynamics of these systems.
6:00
PM-8:00 PM, Moscone Conv Ctr -- Hall D, Poster;
General Papers:
Polymers in Nanotechnology
POLY
122 Sunil
Kulkarni ,
Stephanie L. Wunder, and George Baran. Dept.
of Chemistry & Center for Bioengineering
and Biomaterials.
Investigation
of T g
in crosslinked methacrylate resins using DSC and
fluorescence spectroscopy. Fluorescence
probes are used to detect glass transition temperatures,
Tg, in linear glassy polymers near interfaces,
such as in ultrathin films or under nanoscale
confinement. The change in slope of the fluorescent
intensity with temperature can sometimes be correlated
with Tg, depending on the strength of Tg, the
type of probe and its interaction with the polymer
of interest. Since many composites are prepared
from glass fillers and crosslinked resins, in
which the interphase region is of interest, it
would be useful to determine whether changes in
Tg or crosslink density in the bulk, and subsequently
at the interface, could be invested using fluorescence
techniques. We have prepared a series of lightly
crosslinked methacrylate based resins from methyl
methacrylate (MMA)/triethylene glycol dimethacrylate
(TEGDMA) or MMA/bisphenol A glycidylmethacrylate
(BisGMA), in which a Tg could be observed calorimetrically,
and measured the temperature dependent fluorescence
using pyrene or the intrinsic fluorescence of
BisGMA
7:00
PM-9:00 PM, Moscone Convention Center -- Hall
D; Poster Session.
MEDI
71 Muralidhar
R Mallireddigari ,
V R Pallela, S C Cosenza, S C Bell, B Akula,
V Billa, R Patti, E. P Reddy, and MVR Reddy.
Fels Institute for Cancer Research, Temple
University School of Medicine & Department
of Medicinal Chemistry, Onconova Therapeutics
Inc, Lawrenceville, NJ.
Design,
synthesis and testing of novel styryl benzyl sulfones
as potent anti-cancer agents .
The
lack of selectivity of many cancer agents and
the occurrence of intrinsic or acquired resistance
of tumors to chemotherapy have been a major obstacles
in the treatment of cancer. The efficacy of chemotherapeutic
treatment of cancers is limited by the development
of drug resistance. Among the multiple mechanisms
involved, it is likely that defects in apoptotic
pathways are responsible for reduced cell ability
to undergo drug-induced apoptosis. Apoptosis,
MONDAY
8:10
AM-12:00 PM, Moscone Convention Center -- Room
135. Peptide
Bond Isosteres
10:10
a.m. ORGN 250 Scott
McN. Sieburth ,
Wondwossen D. Arasho, Madhusudhan Purushotham,
Sushmita Sen, Jin Kyung Kim, and Richard P.
Gaines. Department of Chemistry.
Silanediols
as neutral, stable hydrated carbonyl mimics for
protease inhibitor design .
Silicon,
the element most similar to carbon, differs from
carbon by its inability to form strong double
bonds. Silanediols are therefore analogous to
stable, hydrated carbonyls. We have prepared and
evaluated three structures as nonhydrolyzable
dipeptide analogues. In each case, derivatives
of these central components provided low nanomolar
inhibition of metallo- and aspartic proteases.
Advances in efficient methods for their asymmetric
synthesis now makes these silanediols readily
accessible. Application of silanediol inhibitors
to the inhibition of serine proteases will also
be discussed.
1:00
PM-5:00 PM, Moscone Conv Center -- Room 131. Asymmetric
Reactions and Syntheses
2:00
p.m. ORGN 302 Peiling
Chen & Scott McN. Sieburth .
Dept. of Chemistry.
Rearrangements
and reactivities of 2-pyridone [4+4] photoadducts
.
Application
of the efficient [4+4] photocycloaddition of 2-pyridones
to two classes of natural products has been studied
in model systems. A sequence of [4+4] cycloaddition
– [3,3] rearrangement – and retro-Mannich reactions
assembles unsymmetrically coupled piperidines
with predictable stereochemistry. In a second
model study, intramolecular [4+4] cycloaddition
of a pyridone and a furan yields a pentacyclic
cyclooctadiene. The transannular cyclization
of this intermediate was expected to give the
tetraquinane framework of the crinipellins has
led to several new reaction pathways for these
strained photoadducts
1:30
PM-4:45 PM, Moscone Convention Center -- Room
262. Frontiers
in Geochemistry: Commemorating the 25th Anniversary
of the ACS-Geochemistry Division
3:25
p.m. GEOC 74 Daniel
R. Strongin ,
Jun Hao, Eelin Lim, & Martin A Schoonen.
Department of Chemistry, Center for Environmental
Molecular Science & Department of Biology,
Temple University, & Stony Brook University,
Stony Brook.
Effect
of adsorbed lipid on pyrite oxidation under abiotic
and biotic conditions .
Acid
Mine drainage (AMD) is a significant environmental
problem. Bacteria play a significant role in causing
AMD, since they play a large role in catalyzing
the oxidation of pyrite (a root cause of AMD)
and the subsequent development of acidic conditions.
The chemolithoautotrophic species, Acidithiobacillus
ferrooxidans, and the heterotrophic species, Acidiphilium
acidophilum were investigated on the pyrite surface
with atomic force microscopy (AFM) and aqueous
batch reaction rate measurements. AFM was used
to investigate the growth of these bacteria on
the pyrite surface at a pH close to 2, with and
without an adsorbed organic layer of phosphocholine
lipid. Specifically, 1,2-bis(10,12-tricosadiynoyl)-sn-Glycero-3-Phosphocholine
lipid (23:2 Diyne PC)was used, which shows a strong
inhibitory effect on both the abiotic and biotic
oxidation rate of pyrite. AFM showed that under
the experimental conditions used in this study,
the lipid formed a bilayer-structure on the mineral
surface, which was stable for long periods (>25
days) of time in the presence of the bacteria.
In situ AFM also showed that the adsorption of
the phosphocholine lipid resulted in a decrease
in the amount of surface-bound bacteria (relative
to a lipid-free surface), due to the strong interaction
of the phosphate functional group of the lipid
and the pyrite surface.
8:00
PM-10:00 PM, Moscone Convention Center -- Hall
D, Sci-Mix
PMSE
326 Quan
Wan ,
George Baran, Sunil Kulkarni, and Solomon Praveen.
Center for Bioengineering and Biomaterials &
Department of Chemistry, Temple University,
& Department of Chemistry, Drexel University.
Bio-inspired
polymer dental composites with ordered filler
arrangement .
Structural
optimization is a key factor in improving physical
and mechanical properties of polymer matrix composites.
Inspired by a variety of hierarchically ordered
materials in nature (e.g. nacre and teeth), we
have synthesized novel composites with ordered
filler arrangement for the application of dental
restorations. Using colloidal crystallization
as our primary strategy, we were successful in
obtaining millimeter scale composite materials
with silica particles regularly arranged in a
crosslinking resin matrix. We demonstrate that
ordering of monodisperse silica beads (500 nm)
in triethyleneglycol dimethacrylate (TEGDMA) matrix
can be realized through either colloidal dispersion
or solvent sedimentation of the filler beads.
Scanning electron microscopy (SEM) showed that
the cured composites had a face-centered cubic
(fcc) structure. Compressive mechanical testing
indicates that our ordered composites have slightly
lower modulus but significantly higher strength
and failure strain compared with non-ordered composites.
Our ordering approach may also provide the potential
of enhancing composite toughness.
POLY
122 Sunil
Kulkarni ,
Stephanie L. Wunder, and George Baran. Department
of Chemistry & Center for Bioengineering
and Biomaterials.
Investigation
of T g
in crosslinked methacrylate resins using DSC and
fluorescence spectroscopy .
Fluorescence
probes are used to detect glass transition temperatures,
Tg, in linear glassy polymers near interfaces,
such as in ultrathin films or under nanoscale
confinement. The change in slope of the fluorescent
intensity with temperature can sometimes be correlated
with Tg, depending on the strength of Tg, the
type of probe and its interaction with the polymer
of interest. Since many composites are prepared
from glass fillers and crosslinked resins, in
which the interphase region is of interest, it
would be useful to determine whether changes in
Tg or crosslink density in the bulk, and subsequently
at the interface, could be invested using fluorescence
techniques. We have prepared a series of lightly
crosslinked methacrylate based resins from methyl
methacrylate (MMA)/triethylene glycol dimethacrylate
(TEGDMA) or MMA/bisphenol A glycidylmethacrylate
(BisGMA), in which a Tg could be observed calorimetrically,
and measured the temperature dependent fluorescence
using pyrene or the intrinsic fluorescence of
BisGMA
PMSE
369 Sunil
Kulkarni ,
Rahul Ranade, Rajesh Madathingal, and Stephanie
L. Wunder. Department of Chemistry
Mechanical
properties of silica colloidal crystals/methacrylate
nanocomposites .
Composite
materials prepared using nanoparticle fillers
are of increasing interest, but are difficult
to blend at high volume fractions due to their
high viscosity. One approach to preparing these
materials is to first form a colloidal crystal
of the filler and the neat resin, followed by
polymerization to form the ordered composite.
We have prepared ordered composites from monodisperse
250 and 500 nm SiO2 beads, and disordered composites
from mixtures of the 250 and 500nm SiO2 beads.
In both cases, the resin matrix was crosslinked
TEGDMA/MMA. Comparison of mechanical property
data showed that there was a two-fold improvement
in the flexural modulus for the ordered compared
with the disordered composite, and both increased
with respect to the neat resin. The flexural and
compressive strength were similar for the ordered
and disordered composites at the same composition
and thus same interfacial area.
ORGN
122 Franklin
A Davis, He Xu , Yongzhong
Wu, and Junyi Zhang. Department of Chemistry.
Asymmetric
synthesis of cis-2,5-disubstituted pyrrolidines
from sulfinimine-derived pyrrolidine 2-phosphonates
and its application to the synthesis of pyrrolidine
225C .
The
Horner-Wadsworth-Emmons reaction of aldehydes
with sulfinimine derived 3-oxo pyrrolidine phosphonates
represents new methodology for the asymmetric
synthesis of ring-functionalized cis-2,5-disubstituted
3-oxo pyrrolidines. This methodology is demonstrated
with the asymmetric synthesis of pyrrolidine 225C.
TUESDAY
8:00
AM-12:10 PM, Moscone Convention Center -- Room
134.
Arthur
C. Cope Award and Arthur C. Cope Scholar Awards
10:45
a.m. ORGN 339 Franklin
A. Davis ,
Department of Chemistry.
Award
Address (Arthur C. Cope Scholar Awards, sponsored
by Arthur C. Cope Fund). Adventures in sulfur-nitrogen
chemistry .
A
brief history of the discovery of N-sulfonyloxaziridines
and sulfinimines (N-sulfinyl imines) will be presented.
Recent developments in the application of sulfinimine-derived
chiral building blocks for the asymmetric synthesis
of amine derivatives will be discussed.
WEDNESDAY
8:30
AM-12:40 PM, Grand Hyatt -- Portrero. Environmental
Interfaces
12:10
p.m. COLL 463 Daniel
R. Strongin ,
Gang Liu, Sudeep Debnath, Kristian W. Paul,
F. Marc Michel, John B. Parise, & Donald
Sparks. Department of Chemistry &
Center for Environmental Molecular Science,
Temple University, University of Delaware, &
Stony Brook University.
Surface
reactivity of ferrihydrite nanoparticles toward
gaseous SO 2.
Nanoparticles
with nominal sizes of 3 and 6 nm were assembled
within ferritin, an iron storage protein. The
crystallinity and structure of the particles,
after removal of the protein coat by heating to
373 K in a reactive ozone environment, were evaluated
using electron microscopy and atomic force microscopy
(AFM), and scanning tunneling microscopy (STM).
Electron microscopy showed that both amorphous
and crystalline nanoparticles were present, with
the degree of crystallinity improving with increasing
size of the particles. The dominant phase of the
crystalline nanoparticles was ferrihydrite. The
morphology and electronic structure of the nanoparticles
supported on Au(111) were characterized using
a combination of AFM and STM. Scanning tunneling
spectroscopy (STS) measurements of the band gap
associated with the 6 nm nanoparticles were consistent
with bulk ferrihydrite, whereas a smaller band
gap was measured for the 3 nm nanoparticles. The
interaction of gaseous SO2 with the ferrihydrite
nanoparticles was investigated using attenuated
total reflectance Fourier transform infrared (ATR-FTIR)
spectroscopy, and the results were interpreted
with the aid of molecular orbital/density functional
theory (MO/DFT) frequency calculations. The reaction
of SO2 with the nanoparticles resulted in a variety
of sulfur oxyanion surface species. In particular,
the reaction led to the formation of a mixture
of sulfite, bisulfite, sulfate and bisulfate.
The relative ratio of sulfur oxyanions and the
rate in which they formed was a sensitive function
of the ferrihydrite particle size.
7:30
PM-10:00 PM, Moscone Convention Center -- Hall
D. Poster
Session
PHYS
514 Goutham
Kodali and Robert J. Stanley .
Department of Chemistry
Electronic
properties of 2-aminopurine as measured by Stark
spectroscopy.
2-Aminopurine
(2Ap) is an adenine analog that has a high fluorescence
quantum yield. Its fluorescence yield decreases
significantly when the base is incorporated into
DNA. This makes it a very useful real-time probe
of DNA structure. However, the basic mechanism
underlying 2Ap fluorescence quenching by base
stacking is not well understood. A critical element
in approaching this problem is obtaining an understanding
of the electronic structure of the excited state.
We have explored the excited state properties
of 2Ap in frozen LiCl salt solutions using Stark
spectroscopy. The difference dipole moment from
our experiment is in good agreement with theoretical
calculations reported by other groups. Using the
direction of the transition dipole moment as a
reference, we estimated the magnitude and direction
of the excited state dipole moment of the state
reached upon absorption of near-UV light.
THURSDAY
8:00
AM-12:00 PM, Moscone Convention Center -- Room
131.
Proteins,
Peptides, Amino Acids, and Enzyme Inhibitors
8:00
a.m. ORGN 874 Sushmita
Sen
& Scott McN. Sieburth. Dept. of Chemistry.
Fluorosilanes:
Synthesis and applications in silanediol-based
protease inhibitors .
The
Si-F bond is one of the strongest covalent bonds.
Fluorosilanes, unlike chlorosilanes are moisture
stable and can be easily prepared. A novel method
to synthesize butenyl-diphenyl-fluorosilanes had
been developed. This intermediate can react with
metallated amines to give á
-amino
silanes. Alternatively, treatment with lithium
yields the silyl anion, which reacts with activated
imines to also give á
-amino
silanes. These products are then readily converted
to silanediol protease inhibitors.
6:00
PM-8:00 PM, Moscone Conv Center -- Hall D,
Joint PMSE/POLY Poster Session
PMSE
326 Quan
Wan ,
George Baran, Sunil Kulkarni, and Solomon Praveen.
Center for Bioengineering and Biomaterials &
Department of Chemistry, Temple University,
& Department of Chemistry, Drexel University.
Bio-inspired
polymer dental composites with ordered filler
arrangement. Structural
optimization is a key factor in improving physical
and mechanical properties of polymer matrix composites.
Inspired by a variety of hierarchically ordered
materials in nature (e.g. nacre and teeth), we
have synthesized novel composites with ordered
filler arrangement for the application of dental
restorations. Using colloidal crystallization
as our primary strategy, we were successful in
obtaining millimeter scale composite materials
with silica particles regularly arranged in a
crosslinking resin matrix. We demonstrate that
ordering of monodisperse silica beads (500 nm)
in triethyleneglycol dimethacrylate (TEGDMA) matrix
can be realized through either colloidal dispersion
or solvent sedimentation of the filler beads.
Scanning electron microscopy (SEM) showed that
the cured composites had a face-centered cubic
(fcc) structure. Compressive mechanical testing
indicates that our ordered composites have slightly
lower modulus but significantly higher strength
and failure strain compared with non-ordered composites.
Our ordering approach may also provide the potential
of enhancing composite toughness.
PMSE
369 Sunil
Kulkarni ,
Rahul Ranade, Rajesh Madathingal, and Stephanie
L. Wunder. Department of Chemistry.
Mechanical
properties of silica colloidal crystals/methacrylate
nanocomposites .
Composite
materials prepared using nanoparticle fillers
are of increasing interest, but are difficult
to blend at high volume fractions due to their
high viscosity. One approach to preparing these
materials is to first form a colloidal crystal
of the filler and the neat resin, followed by
polymerization to form the ordered composite.
We have prepared ordered composites from monodisperse
250 and 500 nm SiO2 beads, and disordered composites
from mixtures of the 250 and 500nm SiO2 beads.
In both cases, the resin matrix was crosslinked
TEGDMA/MMA. Comparison of mechanical property
data showed that there was a two-fold improvement
in the flexural modulus for the ordered compared
with the disordered composite, and both increased
with respect to the neat resin. The flexural and
compressive strength were similar for the ordered
and disordered composites at the same composition
and thus same interfacial area.
PMSE
365 Jiangyue
Zhang
and Stephanie L. Wunder. Department of Chemistry.
Investigation
of supported lipid layers on OTS modified spherical
silica surfaces.
Supported
lipid layers are used in applications such as
biosensor devices. In the current investigation,
silica nanometer size beads were investigated
as spherical solid supports. Ocatdecyltrichlorosilane
(OTS) self-assembled monolayers (SAMs) were formed
on monodisperse silica beads with sizes ranging
from 20nm to 500nm. Both bead diameters and OTS
modified bead diameters were measured by dynamic
light scattering (DLS). Lipid DPPC monolayers
were formed on the OTS modified surface by fusion
of the lipid vesicles. The amount of OTS and lipid
attached to the silica surface was investigated
by thermogravimetric analysis (TGA) as a function
of incubation time and temperature.
also
known as programmed cell death, is a physiologic
cell suicide mechanism that controls cell number
in the tissues of metazoans. Apoptosis is a major
modality by which tumor cells can be eliminated
and the identification of new drugs able to induce
the death program in different tumor cell types
is an important goal in cancer therapy and may
provide new useful tools for the treatment of
patients with drug-resistant malignancies. Because
of our ongoing program in the antitumor evaluation
of novel chemical structures that induce apoptosis
in different cancer cell types, we became interested
in the synthesis of styryl benzyl sulfones, which
are altogether belong to a new class of anti-tumor
agents. Herein we report the synthesis,
structure activity relationship, in vitro kinase
activity and cytotoxicity studies of some novel
styryl benzyl sulfones.
8:00
PM-10:00 PM, Moscone Convention Center -- Hall
D, Poster Asymmetric
Reactions and Syntheses, Metal-Mediated Reactions,
Combinatorial, Parallel, and Solid-Phase Chemistry
ORGN
122 Franklin
A Davis, He Xu , Y. Wu, &
J. Zhang. Dept. of Chemistry.
Asymmetric
synthesis of cis-2,5-disubstituted pyrrolidines
from sulfinimine-derived pyrrolidine 2-phosphonates
and its application to the synthesis of pyrrolidine
225C .
The
Horner-Wadsworth-Emmons reaction of aldehydes
with sulfinimine derived 3-oxo pyrrolidine phosphonates
represents new methodology for the asymmetric
synthesis of ring-functionalized cis-2,5-disubstituted
3-oxo pyrrolidines. This methodology is demonstrated
with the asymmetric synthesis of pyrrolidine 225C.
ORGN
123 Franklin
A Davis, He Xu , and Junyi Zhang.
Department of Chemistry.
Asymmetric
synthesis of trans-2,6-disubstituted piperidines
from sulfinimine-derived d
-amino
b
-ketophosphonates.
Total synthesis of (-)-myrtine .
N
-Sulfinyl
d
-
amino
b
-
ketophosphonates,
readily prepared from enantiopure sulfinimines,
are transformed to dihydropyridones, which are
subject to Michael addition and dephosphonylation
to afford trans-2,6-disubstituted piperidines.
The total synthesis of (-)-myrtine is described.
ORGN
125 Alexander
Augustine ,
Franklin A. Davis & J. Zhang. Dept. of Chemistry.
Asymmetric
synthesis of pseudodistomin E from N-sulfinyl
d-amino b-ketoester enaminones .
N
-Sulfinyl
d
-
amino
b
-
ketoester
enaminones 1 , undergo an intramolecular
Michael addition followed by a retro-Michael type
elimination upon one pot hydrolysis, to give enantiopure
2,4,5-trisubstituted-2,3-dihydropyridones. These
dihydropyridones can be transformed into the corresponding
all cis -2,4,5-trisubstituted piperidines
by hydrogenation and controlled borohydride reduction.
Utilization of this methodology led to the first
asymmetric syntheses of the marine alkaloid pseudodistomin
E, a potential anti-tumor agent.
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