Transcript Slide 1

Novel Materials for Energy Conservation and Sensors
Samantha D. Hastings, Qun Zhao, Jason L. Freeman, Justin T. Sheff, Samuel B. Owens Jr.,
Yuanli Zhang, Jianwei Wang, Christopher M. Lawson, and Gary M. Gray
Department of Chemistry, University of Alabama at Birmingham, 901 14th St S, Birmingham, AL, 35294
Introduction
Our group has been involved in a collaborative effort to develop new materials that can be useful in two areas, energy conservation and sensors. The element that unites these diverse topics of research is the study of the linear and non linear optical
properties of novel materials. Specifically, we have developed a series of fluorescent molecules that fall into two classes, phosphorus-substituted bithiophenes and metallacrown ethers. This effort is headed up by University of Alabama at Birmingham
(UAB) Chemistry and Physics researchers, and the work involves collaborative work with several NSF EPSCoR RII research thrusts. Other collaborators include research groups from the Chemistry Department of the University of Mississippi, the
Chemistry Department of the University of Montevallo, and Redstone Arsenal.
LEDs
b
λexc(nm) λem(nm)

[nm]
F
a
9O
9S
9Se
10O
10S
322
328
333
321
339
385
395
397
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395
a
In CH2Cl2 solution. b Fluorescence Stokes shift.
(10%) relative to quinine sulfate in 0.1 M H2SO4.
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67
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59
56
c
QF
Sensor Protection
Light emitting Diodes (LEDs) are
increasingly being incorporated
into electronic devices including
lights sources and electronic
displays, as they are more energy
efficient than the current
technology. Phosphorussubstituted bithiophenes
synthesized by our group have
been shown to have high quantum
yields in the blue region of visible
light, making them candidates to
be used in light-emitting diodes.
a,c
0.14
0.27
~0
0.07
0.21
Fluorescence quantum yield
F
L
U
O
R
E
S
C
E
N
C
E
Catalysis
Rate (k) Regioselectivity
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2
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5
6
sec -1
5.5x10-4
2.3 x10-4
2.6x10-4
1.1x10-4
9.6x10-5
9.1x10-5
%Iso:%N
77:23
83:17
83:17
43:57
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Alkali
Pressure
Salt
-1xLiBPh4*3dme
1xNaBPh4
-1xLiBPh4*3dme
1xNaBPh4
atm
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20
5
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5
Conditions (all ratios are molar): CO/H2 1:1, T 80 0C P (CO/H2), substrate/Rh 1000, k (s_1) at ligand/Rh = 1.2. No
hydrogenation was observed. % iso/% n ratio was determined when pressure change was no longer observed using
1H NMR. The differences in the % iso and % n were less than 2% for duplicate runs.% Conversion of styrene for all
reactions was greater than 99%. The pseudo first order rate constant (k) was obtained from a first order fit of pressure
drop vs. time using Graphical Analysis software
Alkene Hydroformylation is an important industrial reaction that is
responsible for the production of 15 billion pounds of aldehydes
per year. The use of catalysts in these reactions greatly reduces the
energy spent and waste produced. Our group has synthesized a
remarkably versatile bimetallic catalyst that displays
unprecedented tunability of the regioselectivity in the
hydroformylation of styrene while maintaining high reaction rates.
Decreasing the syn gas pressure greatly increases the selectivity for
the linear aldehyde while increasing the syn gas pressure and
adding an alkali metal salt greatly increases the selectivity for the
iso aldehyde.
Optical Power Limiters are
materials that can prevent eye and
optical sensor damage.
All systems have a light intensity
threshold for damage, therefore
lasers and other sources of high
energy light sources can render
sensors permanently or
temporarily ineffective. The
criteria for OPLs are that most of
the low intensity incident light
passes through the material yet
most of the high intensity incident
light is absorbed by the material.
O
C
O
C
R2 O
P
Sensing Element
O
Mo
C
O
C P
R2 O
O
O
C
O
O
n
Molecular Sensors are molecules with a signature spectroscopic
signal that can bind ions and small molecules. Once bound, the
spectroscopic signal changes, resulting in a highly sensitive,
quantitative method that can detect a variety of chemical species.
31P NMR, IR, and fluorescence spectroscopy can be used to
monitor the binding event. Our group has rigorously studied the
binding of alkali metal salts to a model metallacrown ether
compound via 31P NMR. Our new approach to analyzing the
binding allows both the number of solvent molecules displaced
and the intrinsic binding constant to be calculated. These
provided insight into the binding mechanism and may allow
improved molecular sensors to be developed.
R2 O
P
C
C
O
O
O
C
+ MX
P
R2 O
O
O
n
C
O
C
O
The authors would like to thank UAB-Chemistry and Physics Department, Nathan Hammer at the University of Mississippi, Houston Byrd at the University of Montevallo,
Henry Everitt at the Redstone Arsenal, Junpeng Guo at UAH, Army Research Laboratories Cooperate Research Agreement, GRSP NSF-EPSCoR Fellowship and NSFEPSCoR UAB Center for Optical Sciences and Spectroscopies for funding and support.
http://www.coss.phy.uab.edu/
O
R2 O
P
O
+
M
Mo
MX = LiBPh4, NaBPh4; n = 0, 1; R2 = O O
Acknowledgments
Center for Optical Sciences and Spectroscopies
O
C
O
Mo
O
O
O
C
P
R2 O
O
O
n