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The Study of Dithienyl Quinoxaline Complexes and Their ApplicationsMichael Morgan
Molecules of Interest
(MWM5)(NiEB4)
PhotosensitizerPossible pH Sensor
TICT Background
Synthesis
46%
(1)
Synthesis
(MWM5)
19.3%
(1)
AcOH
Synthesis
Synthesis
55%
(EB4) (NiEB4)
Phthalocyanines for PDT• PDT=Photodynamic Therapy
• Need a photosensitizer to produce singlet oxygen
• Singlet oxygen is known to cause apoptosis in nearby cells
How Do Photosensitizers Produce Singlet Oxygen?
How Does Singlet Oxygen Kill Cells?
Experimental• 1,3-diphenyllisobenzofuran (DPBF) has been known to
undergo the reaction below when singlet oxygen is present
• This reaction results in a decrease of absorbance at 415nm (breaking conjugation)
Results
300 400 500 600 700 8000
0.2
0.4
0.6
0.8
1
Irradiation Study ZnEB4
Wavelength (nm)
Absorbance
Q Band
ZnEB4 Absorbance Spectra
280 330 380 430 480 530 580 630 6800
0.02
0.04
0.06
0.08
0.1
0.12
0.14
ZnEB4 in Toluene
Wavelength (nm)
Absorbance
Soret Band
Q Band
Results
0 20 40 60 80 100 120 140 1600
0.05
0.1
0.15
0.2
0.25
0.3
f(x) = 0.00175697493214615 x + 0.00248226534639431R² = 0.999468562082012
f(x) = 0.00133643620308353 x + 0.00121087201860499R² = 0.995688629537078
f(x) = 0.00304793620140097 x + 0.00349389886740831R² = 0.998344049634408
Singlet Oxygen Generation
ZnEB4(Toluene)
Linear (ZnEB4(Toluene))
EB4
Linear (EB4)
NiEB4
Linear (NiEB4)
Irradiation Time (s)
ln(A0/A)
Singlet Oxygen Quantum Yield
Compound Quantum Yield
EB4 0.022
ZnEB4 0.050
NiEB4 0.030
Equation: ΦZnPc=0.58slope of ZnPc irradiation plot=0.0349
Φ=ΦZnPc (slope of irradiation plot/slope of standard irradiation plot)
Pc Conclusions• Successful generation of singlet oxygen
• Results suggest that Zn and Ni were coordinated to EB4• Still awaiting mass spectrometry results for confirmation of
structure
• Molecules need to be synthesized and tested for body toxicity for photodynamic therapy
• Further studies could include different metal ion centers, and different substituents for base EB4 molecule
Possible pH Sensor• Characterized new molecule by 13C and 1H NMR spectroscopy
• Characterized absorbance properties by UV/Vis and fluorescence spectroscopy
• Absorbance changes when pH is varied
(MWM5)
Absorbance of MWM5
300 320 340 360 380 400 420 440 4600
0.01
0.02
0.03
0.04
0.05
0.06
0.07
Absorbance in Different Solvents
DMSO
Acetonitrile
Dichloromethane
Ethanol
Wavelength (nm)
Molar Absorptivity (cm-1 uM-1)
Fluorescence of MWM5
400 450 500 550 6000
2000
4000
6000
8000
10000
12000
14000
Fluorescence of MWM5
KOH:EtOH (0.331 uM)
DMSO (1.07uM)
Acetonitrile (0.01mM)
Wavelength (nm)
Fluorescence Intensity
(counts/s)
pH Study
320 370 420 470 520 5700
0.2
0.4
0.6
0.8
1
pH Study MWM5
pH 11.89pH 10.79pH 9.56pH 7.34pH 5.27pH 3.85
Wavelength (nm)
Absorbance
Absorbance vs. pH
3 4 5 6 7 8 9 10 11 12 130.4
0.5
0.6
0.7
0.8
0.9
1
Absorbance (366nm)
Absorbance (366nm)
pH
Absorbance
Conclusions• Possible pH sensor
• Solution turns yellow at higher pH
• Further studies could include fluorescence studies at varyingpH
• Could change substituents and position of alcohol group
• Want sensitive range at physiological pH
Special Thanks• Dr. Kevin Schultz
• Goucher College Chemistry Department
• Emma Baker
• Claasen Fund
References• Ali ErdoGmus, Diphenylethoxy-substituted metal-free and metallophthalocyanines as
potential photosensitizer for photodynamic therapy: synthesis and photophysical and photochemical porperties; Turkish Journal of Chemistry; 2014; 38, 1083-1093.
• Thomas B. Rauchfuss, π-Complexes of Phthalocyanines and Metallophthalocyanines; Organometallics; 2000; 19, 4767-4774.
• Xian-Fu Zhang, The photostability and fluorescence properites of diphenylisobenzofuran; Journal of Luminescence; 2011; 131, 2263-2266.
• Zihui Chen, Octathienyl/phenyl-substituted zinc phthalocyanines J-aggregated through conformational planarization; Dalton Transactions; 2011; 40, 393.
• Josefsen, L.; Boyle, R.; “Photodynamic Therapy and the Development of Metal-Based Photosensitizers”; Metal-Based Drugs, 2008, ID: 276109.