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Intersystem Crossing and Energy Transfer in Charge-Transfer Complexes

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Intersystem Crossing and Energy Transfer in Charge-Transfer Complexes Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1962 Intersystem Crossing and Energy Transfer in Charge-Transfer Complexes. Nicholas D. Christodouleas Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Christodouleas, Nicholas D., "Intersystem Crossing and Energy Transfer in Charge-Transfer Complexes." (1962). LSU Historical Dissertations and Theses. 770. https://digitalcommons.lsu.edu/gradschool_disstheses/770 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. This dissertation has been 63-2764 microfilmed exactly as received CHRIS TODOULEAS, Nicholas D., 1932- INTERSYSTEM CROSSING AND ENERGY TRANS­ FER IN CHARGE-TRANSFER COMPLEXES. Louisiana State University, Ph.D., 1962 Chemistry, physical University Microfilms, Inc., Ann Arbor, Michigan Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. INTERSYSTEM CROSSING AND ENERGY TRANSFER IN CHARGE-TRANSFER COMPLEXES A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Chemistry by Nicholas D. Christodouleas University of Athens (Greece), 1956 August, 1962 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ACKNOWLEDGMENTS I wish to express my gratitude to Dr. S. P. McGlynn, who directed this research and who aided me patiently and understandingly. I wish to express my appreciation to Professor H. Williams to whom I owe my being at Louisiana State University. Finally, I thank Dr. J. Nag-Chaudhuri for her valuable assistance during the course, of this work. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TABLE OF CONTENTS CHAPTER PAGE ACKNOWLEDGMENTS ....................................... ii LIST OF TABLES....................................... v LIST OF FIGURES....................................... vi ABSTRACT ............................................. viii PART I (THEORETICAL) A. ORGANIC MOLECULAR COMPLEXES ............................ 1 Introduction ......................................... 1 The Origin of Charge-Transfer Theory ................. 2 Formulation of the Theory ........................... 3 Resonance in the Charge-Transfer Complexes ........... 5 Polarization of Charga-Transfer Transition........... 8 Charge-Transfer Ground State Interaction and Intensity of Charge-Transfer B a n d ........................... 9 Paths of Excitation and Energy distribution.......... 13 The Perturbation of the Donor-Triplct State in the Charge-Transfer Complexes ......................... 15 B. THEORETICAL CONSIDERATIONS OF SPIN-ORBITAL COUPLING INTERACTION......................................... 17 PART II (RESULTS OF THE PRESENT RESEARCH) A. ELECTRONIC ABSORPTION SPECTRA OF CHARGE-TRANSFER COMPLEXES OF NAPHTHALENE WITH HEAVY ATOM CONTAINING ACCEPTORS . 22 Introduction ......................................... 22 Experimental ......................................... 23 Results and Discussion . 2 3 Stability Constants (Kx) and Electronegativity of the Acceptors....................................... 24 Comparison of the Values of Molar Absorption Coeffi­ cients Ec and Oscillator Strengths F ' s .......... 24 Free Energy of Formation of Naphthalene Tetrahalo- phthalic Anhydride Complexes ................... 27 Correlation of Ec or Ex and Kx of the Complexes with _^max of C-T B a n d ............................. 27 iii Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CHAPTER PAGE Geometrical Structures of C-T Complexes ............ 28 Width of Complex Absorption Bands ................. 29 The Effect of Solvent on the Stability Constants of the Complexes................................... 29 B. INTERSYSTEM CROSSING IN CHARGE-TRANSFER COMPLEXES OF NAPHTHALENE WITH HEAVY ATOM CONTAININGACCEPTORS .... 40 Introduction ........................................ 40 Experimental ....................................... 41 Results........................................ 43 Discussion......................................... 46 Addendum........................................... 63 C. CHARGE-TRANSFER EMISSION SPECTRA..................... 68 Introduction ....................................... 68 Experimental ....................................... 70 Result and Discussion ............................. 72 BIBLIOGRAPHY ......................................... 82 VITA ................................................. 86 iv Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. L IS T OF TABLES TABLE PAGE I. Spectrophotometric and Thermodynamic Values for Some Naphthalene Complexes 30 II. Molar Absorption Coefficient £e of Some Naphthalene Complexes Calculated on the Basis of Molarity of the Complex 31 III. Spectrophotometric and Thermodynamic Values for Some Naphthalene Complexes in Different Solvents 33 IV. Fluorescence and Phosphorescence Intensities in the Total Emission Spectra of Naphthalene-TCPA Complex 51 V. Fluorescence and Phosphorescence Intensities in the Total Emission Spectra of Naphthalene-TBPA System 52 VI. Fluorescence and Phosphorescence Intensities in the Total Emission Spectra of Naphthalene-TIPA Complex 53 VII. Fluorescence and Phosphorescence Intensities in the Total Emission Spectra of Naphthalene-sym-TNB 54 VIII. Comparison of Fluorescence and Phosphorescence Intensities in the Total Emission Spectra of Naphthalene with TCPA, TBPA and TIPA 55 IX. Relative Fluorescence and Phosphorescence Intensities of Naphthalene-TCPA Measured with the Aminco-Keirs Spectro­ photometer 64 X. Relative Fluorescence and Phosphorescence Intensities of Acenaphthalene-sym-TNB Measured with the Aminco-Keirs Spectrophotometer 65 XI. Relative Fluorescence and Phosphorescence Intensities of Phenanthrene-sym-TNB Measured with the Aminco-Keirs Spectrophotometer 66 XII. Comparison of v^max (Absorption) and ^ m a x (Emission) for Some C-T Complexes 81 v Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LIST OF FIGURES FIGURE PAGE 1 . General Potential Energy Diagram of Charge-Transfer Complexes 7 2 . Plot of Molar Absorption Coefficient £ .* vs. Wave Number of Absorption in the Complexes: Naphthalene-TCPA, Naphthalene-TBPA, Naphthalene-TIPA and Naphthalene-2,4,7 TN-Fluorenone 35 3. Molar Absorption Coefficients £<e vs. Wave Numbers of Absorption for the Complexes in Other Than Chloroform Solvents 36 4. Plot of Molar Absorption Coefficient^* vs. Peak Wave Length of the C-T Band 37 5. Plot of Stability Constants vs. Peak Wave Length of the C-T Bands of the Naphthalene Complexes in Chloroform Solution 38 6 . Charge-Transfer Spectrum of Naphthalene-2,4,7 TN- Fluorenone at Three Different Temperatures 39 7. Molar Absorption Coefficients of (1) Naphthalene in iso-Octane, (2) TCPA in Chloroform and (3) Naphthalene-TC^Jl in Chloroform 56 8. Total Emission of Pure Naphthalene and Naphthalene-sym-TNB 57 9. Total Emission Spectra of Three Solutions of Naphthalene Complex 58 10. Plot of C f? p/ <^f vs. Concentration of TCPA 59 11. Plot of ^ p / ^ f vs. Concentration of TBPA 60 12. Total Emission Spectra of Naphthalene with Equimolar Amounts of TCPA, TBPA and TIPA 61 13. Plot of ^ p / ( j ?f vs. (SOCF)^ of the Halogens 62 14. Total Emission Spectra of Phenanthrene-sym-TNB Complex 67 vi Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. FIGURE PAGE 15. Emission and Absorption of Anthracene-2,4,7 TN-Fluorenone Complex 73 16. Emission and Absorption of Anthracene-sym-TNB Complex 74 17. Emission and Absorption of Anthracene-TCPA Complex 75 18. Emission and Absorption of Tetraphene-sym-TNB Complex 76 19. Emission and Absorption of Coronene-sym-TNB Complex 77 20. Emission and Absorption of 3, 4 Benzotetraphene-sym-TNB Complex 78 21. Emission and Absorption of Phenanthrene-sym-TNB Complex 79 22. Plot of ^ m a x (Absorption) and ^ max (Emissioi) of Some Charge-Transfer Complexes 80 vii Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ABSTRACT A. The charge-transfer spectra of Naphthalene with a number of organic acceptors such as Tetrachlorophthalic anhydride, Tetrabromo- phthalic anhydride, Tetraiodophthalic anhydride, etc., were investigated. Stability constants of complex formation and other thermodynamic and spectroscopic data are presented. From the positions of the maxima of charge-transfer bands and by comparison of the values of stability constants, it is concluded that Tetraiodophthalic anhydride is the strongest electron-acceptor in the Tetrahalophthalic anhydride series. A linear relationship between max and absorption coefficient has been found in the Tetrahalophthalic anhydride series. The concept of "contact C-T" absorption is introduced and is used, by means of a simple quantum mechanical formulation, for the explanation of the variation of oscillator's strengths of C-T absorption in the Tetrahalophthalic anhydride
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