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.