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Synthesis and Characterization of Metallo-tetraarylazadipyrromethene Complexes Anne Lam Damali Greenaway Mentors: Dr. Chris Hansen and Dr. Jianguo Shao.

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Presentation on theme: "Synthesis and Characterization of Metallo-tetraarylazadipyrromethene Complexes Anne Lam Damali Greenaway Mentors: Dr. Chris Hansen and Dr. Jianguo Shao."— Presentation transcript:

1 Synthesis and Characterization of Metallo-tetraarylazadipyrromethene Complexes Anne Lam Damali Greenaway Mentors: Dr. Chris Hansen and Dr. Jianguo Shao July 05, 2013

2 Objectives To synthesize a ligand and metal complexes To characterize complexes using Electro- chemistry, IR, and UV-visible Spectroscopy

3 Causes for Study Metallo-tetraarylazadipyrromethene complexes exhibit potential application as – fluorescent chemosensors - molecules that change their fluorescence in response to substrate binding – in vitro fluorophores – molecules employed in biochemistry, protein studies, and cell analysis – photosensitive drugs in Photodynamic Therapy

4 Jablonski Diagram for the PDT process Our compounds exhibit strong absorption in the visible range (400 – 780 nm).

5 1,4 Michael Addition Reflux with CH 3 CO 2 NH 4 Synthesis of Free-base Ligand Products confirmed by H-NMR

6 Synthesis of Metallo-complexes Reflux with Ni(CH 3 CO 2 ) 2 · 4H 2 O 22 h Reflux with CH 3 CO 2 NH 4 and CoCl 2 · 6H 2 O 22 h Reflux with Cu(CH 3 CO 2 ) 2 1 h Product purities tested with TLC Ni Co Cu (pure) (free-base ligand)

7 IR Spectra CpdStrong IR Peaks (cm -1 ) FB , 1543, 1351, 1264, 1242, 962, 904, 762 Co 1520, 1476, 1448, 1367, 1248, 1131, 982, 930 Ni 1521, 1476, 1448, 1367, 1249, 1131, 985, 930 Cu 1521, 1476, 1448, 1366, 1250, 1131, 987,928 Ni complex 1 Free Base (tetraarylazadipyrromethene)

8 UV-Visible Spectra in CH 2 Cl 2 Wavelength (nm) Cu FB Co Ni Cpd B-Band (nm) Q-Band (nm) ΔQ (nm) FB Co Ni Cu Free Base (tetraarylazadipyrromethene)

9 UV-Visible Spectra in DMF Wavelength (nm) Cpd B-Band (nm) Q-Band (nm) ΔQ (nm) FB Co Ni Cu Cu FB Co Ni 1 Free Base (tetraarylazadipyrromethene)

10 Electrochemical Introduction A potential is applied to an electrode immersed in a solution, forcing the oxidation/reduction of the analyte. The concentration ratio of the Oxidized and Reduced species (near the electrode) adopts a value consistent with the Nernst Equation. The magnitude of the current is then determined by – Electron-Transfer – the oxidation or reduction of analyte – Mass- Transfer- the transport (diffusion) of analyte to or from the electrode surface in an attempt to equalize the concentrations

11 11 (+) OxidationReduction E 1/2 (-) Cyclic Voltammetry (Theory) (Electron Withdrawal)(Electron Addition) A-A- A+A+ A A + e - - e -

12 Oxidation Reduction Cyclic Voltammetry CH 2 Cl 2,0.1M TBAP Potential (V vs SCE) * * Potential (V vs SCE)

13 Oxidations in CH 2 Cl 2, 0.1M TBAP Potential (V vs SCE)

14 Reductions in CH 2 Cl 2, 0.1M TBAP Potential (V vs SCE) * *

15 Reductions in Pyridine, 0.1M TBAP Potential (V vs SCE) * *

16 Copper Reductions Potential (V vs SCE) DPV CV a) In Pyridine b) In CH 2 Cl 2

17 Different Scan Rates, CH 2 Cl 2, 0.1 M TBAP Potential (V vs SCE) mV/s Potential (V vs SCE) A B C E D Diffusion-Controlled

18 Different Scan Rates, CH 2 Cl 2, 0.1 M TBAP Potential (V vs SCE) mV/s Potential (V vs SCE) A B C E D Diffusion-Controlled

19 Conclusion All three metallo-complexes exhibit two common reversible oxidations with greater relative ease as compared to the free base ligand. Ni and Co complexes share reductive properties from 1 st and 2 nd pyrrole electron additions and 3 rd (and likely 4 th ) phenyl electron additions. Cu complex displays unique electro-reduction properties and the first reduction takes place on the Cu(II) center. All redox processes are diffusion-controlled.

20 Future Work Purification is needed for Co and Ni complexes. Fluorescence spectra will be examined. Are Co, Ni and Cu complexes active catalysts for the DDT reductive dechlorination? To find the solution why Cu complex has a special electro-reduction behavior as respect to Ni and Co complexes. Different substituted groups can be introduced into phenyl rings to fine-tune the properties.

21 Acknowledgments This research was supported by Midwestern State Universitys UGROW program and funded by the Welch Foundation. Thanks to MSU chemistry department, Dr. Rincon, program director, and Drs. Hansen and Shao for advice and mentorship.

22 References Besette, A.; Ferreira, J. G.; Giguere, M.; Belanger, F., Desilets, D.; Hanan, G. S. Inorg. Chem. 2012, 51, OConnor, A.; Mc Gee, M.; Likar, Y.; ponomarev, V.; Callanan, J. J.; Oshea, D. F.; Byrne, A.; Gallagher, W. Int. J. Canc. 2011, 130, Aniello, P.; Gallagher, J.F.; Muller-Bunz, H.; Wolowska, J.; McInnes, E. J.L.; OShea, D. F. Dalton Trans. 2009, Teets, T.; Partyka, J.; Updegraff III, J. J.; Gray, T. Inorg. Chem. 2008, 47, Gorman, A.; Killoran, J.; OShea, C.; Kenna, T.; Gallagher,W.M.; OShea, D. F. J. Am. Chem. Soc. 2004, 126, Kissinger, P. T.; Heineman, W. R.; J. Chem. Educ. 1983, 60,

23 Questions?


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