general: use spectroscopic and computational tools to study thermodynamic and kinetic aspects of...
TRANSCRIPT
General: Use spectroscopic and computational tools to study thermodynamic and kinetic aspects of different systems
Research Focus
1. Energetics and kinetics in Organometallic Chemistry. Relevance: Agriculture: Rational design of anti-ripening compounds
Is it possible to slow down fruit and flower ripening?
Anti-ripening control: Blocking ethylene action
Burg and Burg, Science, 1965, 148, 1190 Sisler and Serek, Bot. Bull. Acad. Sin. 1999, 40, 1
N N
Some anti-ripening compounds:
Lemmer, D. et al., South African Avocado Grower’s Yearbook, 2002, 25, 25
The most effective compounds anti-ripening are cyclic olefins. What is so special about them??
Anti-ripening control: Blocking ethylene action
•An understanding of the metal-olefin interaction is important in designing anti-ripening compounds.•Why are cyclic olefins so special? Ring strain affects olefin-receptor interaction. •Are there any other effects? Is it possible to control the strength of the metal-olefin bond?
W C O 5(olefin) O ptim ized G eom etries:W C O 5(olefin) O ptim ized G eom etries:
15.0
20.0
25.0
30.0
35.0
1 2 3 4 5 6 7 8 9
Number of Carbons
H o
r E
(kca
l/mo
l)
a)
Cedeño and Sniatynsky, Organometallics, 2005, 24, 3882
General: Use spectroscopic and computational tools to study thermodynamic and kinetic aspects of different systems
Research Focus
2. Effects of molecular structure on yields of triplet state of oxygen photosensitizers. Relevance: Clinical: Rational design of efficient photodynamic therapy compounds and fluorescent diagnostic probes.
Are there efficient ways to use light to treat diseases?
The Rational Design ApproachGoal: Establish correlations between the yield of triplet sensitizer and active oxygen species and the molecular structure of the photosensitizer. Correlations will lead to improved sensitizers with optimum yields of triplet sensitizer and singlet oxygen
NovelPhotosensitizers (Prof. T.D. Lash)
Singlet Oxygen Emission (1270 nm)
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0.25
0.3
0 0.0005 0.001 0.0015
Time (s)
Sig
na
l In
ten
sit
y (
V)
x 1
00
00
1O2 yield (Traps, TRF)
Computational Methods
Triplet yield (PAC)
Photoacoustic Sound Waves
-1.2
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0
Time (s)
No
rma
lize
d S
ign
al
(a.u
.)
Reference
Sample
Emission Spectra: Fluorescence yieldTriplet energy
Absorption Spectra
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
300 400 500 600 700 800 900 1000
wavelength (nm)
Ab
so
rba
nc
e
Applications: Treatment of Leishmaniasis
Figure 4. A confocal microscope image showing light emission (bright spots) from a carbaporphyrin inside Leishmania parasites
Figure 4. A confocal microscope image showing light emission (bright spots) from a carbaporphyrin inside Leishmania parasites
28
6.12
3.3
1.4
1.3
0.54
8.52
0 10 20 30 40
CKOEt
CKOMe
Glucantime
AmphotericinB
EC50 (g/mL)
4h per day
2h per day
no light
>1000