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Photostability of laser dyes in sol-gel-derived hosts Item Type text; Dissertation-Reproduction (electronic) Authors Suratwala, Tayyab Ishaq, 1970- Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 05/10/2021 13:21:09 Link to Item http://hdl.handle.net/10150/290697 INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly fi-om the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. 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Contact UMI directly to order. UMI A Bell & Howell Infonnation Company 300 North Zeeb Road, Ann Aibor MI 48106-1346 USA 313/761-4700 800/521-0600 PHOTOSTABILITY OF LASER DYES IN SOL-GEL DERIVED HOSTS by Tayyab Ishaq Suratwala Copyright © Tayyab Ishaq Suratwala 1996 A Dissertation Submitted to the Faculty of the DEPARTMENT OF MATERIALS SCIENCE AND ENGINEERING In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 1996 DMI Nxjmber: 9720676 Copyright 1996 by- Sura twala, Tayyab Ishaq All rights reserved. UMI Microform 9720676 Copyright 1997, by UMI Company. All rights reserved. This microform edition is protected against wiauthorized copying under Title 17, United States Code. UMI 300 North Zeeb Road Ann Arbor, MI 48103 2 THE UNIVERSITY OF ARIZONA ® GRADUATE COLLEGE As members of the Final Examination Committee, we certify that we have read the dissertation prepared by Tayyab Suratwala entitled Photostability of Laser Dyes in Sol-Gel Derived Hosts and recommend that it be accepted as fulfilling the dissertation requirement for the Degree of Doctor of Philosophy W. Bickel Date C Date ////J /9^ Date Date Date Final approval and acceptance of this dissertation is contingent upon the candidate's submission of the final copy of the dissertation to the Graduate College. I hereby certify that I have read this dissertation prepared under my d^ect;i9n and recommejid—trKat it be accepted as fulfilling the dissertation Dissertation Director D.R. Uhlmann Date 3 STATEMENT BY AUTHOR This dissertation has been submitted in partial fiilfillment of requirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library. Brief quotations from this dissertation are allowable without special permission, provided that accurate acknowledgement of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the copyright holder. SIGNED: 4 ACKNOWLEDGEMENTS First of all, I would like to thank my parents. Their love, feith, prayers, and encouragement have been a foundation for my successes. Without their contributions, I would not be where I am today. I would like to thank Professor D-R. Uhlmann "boss" for his advisement, his enthusiasm, and his support. His knowledge and insight on science, technology, industry, and an infinite number of other topics has made discussions with him invaluable. He is a wonderfiil mentor and role model, and I have benefited greatly as a scientist by being his student. Research help and collaboration have been crucial to the successes of this work. Thank you to Professor Zack Gardlimd for the synthesis of the silylated dyes and for the endless number of discussions and advice about the research project and life in the industrial world. Thank you to Kevin Davidson for his help with the lab work and his devotion to the project. Thanks to the collaborators at Optical Sciences, especially Jason Watson and Sandra Bonilla, for the optical measurements and their contributions to this project. I would also like to thank Professor Nasser Peyghambarian for the use of his facilities. Thank you to the other members of my committee. Professor Brian Zelinski, Professor William Bickel, and Professor Elizabeth Krupinski, for reading my dissertation and your comments. Thank you to the financial supporters of this work including the Air Force Office of Scientific Research, the Coming Foundation Fellowship, and the Chapman Fellowship. I would like to thank all my fiiends here in Arizona including my roommates (Sajiv, Joe, Ryan, and JeflO who have made evenings eventful and stress relieving and AML fiiends who were always willing to help with those little things. They made my time spent in Tucson fim and exciting. Finally, thank you to Mustafe, a life-long fiiend, who has always provided me motivation and has driven me to strive for the best of everything. 5 TABLE OF CONTENTS UST OF FIGURES 7 LIST OF TABLES 12 ABSTRACT 14 1) INTRODUCTION/BACKGROUND 16 1.1) Dye Lasers 16 1.2) Ruorescence and Dye/Host Interactions 18 1.3) Photochemistry 23 1.4) Polymer Hosts 29 1.5) Inorganic Hosts 30 1.6) Polyceram Hosts 33 1.7) Coumarin Dyes 34 1.8) Pyrromethene-BFzDyes 36 1.9) SUylated Dyes 38 1.10) Research Objectives 39 2) EXPERIMENTAL 40 2.1) Synthesis of Laser Dyes 40 2.2) Host Chemistry 45 2.2.1) Synthesis ofXerogel Films 45 2.2.2) Synthesis of Polyceram Monoliths 46 2.3) Optical Characterization 55 2.4) FTIR Monitoring of Hydrolysis Reaction Rates 57 2.5) Dye Extraction Measurements 58 2.6) Surface Area and Porosity Measurements 58 2.7) NMR Spectroscopy 58 3) COVALENT BONDING OF LASER DYES TO HOST 60 3.1) Hydrolysis Reaction Rate 60 3.2) Dye Extraction/Thermal Stability 65 3.3) SoUd-State ^Si NMR 71 3.4) Fluorescence EfiBciency 74 3.5) Photostability 76 3.5.1) Fluorescence Photostability 76 3.5.2) Absorption Photostability 79 3.5.3) Effect of Prehydrolysis of the Dye 82 3.5.4) Xerogel Films 84 3.5.5) Polyceram Films 90 3.5.6) Neat Films 94 6 3.6) Spectroscopy 97 3.6.1) Structure Effects of Dye 97 3.6.2) pH Effects 99 3.6.3) Host Effects 109 3.6.4) Drying/gelling effects 116 3.7) Summary: Advantages of Covalent Bonding 121 4) MECHANISM OF PHOTODEGRADATION 122 4.1) Role of Oxygen 122 4.2) Photodegradation Chemistry 125 4.2.1) Degradation Products ofPM-567 125 4.2.2) Acid vs Base Environment 127 4.2.3) Multi-Step Degradation 129 4.3) Types of oxidation processes 131 4.4) Role of Oxygen in Different Hosts 133 5) POROSITY AND PHOTODEGRADATION KINETICS 137 5.1) Control ofPorosity as a Function of Sol-Gel Processing 137 5.2) Control ofPorosity as a Function of Composition 146 5.3) Photostability 155 5.4) Structural Model of the Polycerams 157 5.5) Models to Explain Fluorescence Photostability Behavior 162 5.5.1) Thermal Degradation 163 5.5.2) Singlet-Triplet Equilibration 168 5.5.3) Dyes Located on the pore surface of host 172 6) ADDITIVES TO IMPROVE PHOSTABILITY 184 7) HOW TO MAKE A PHOTOSTABLE DYE/HOST SYSTEM 194 CONCLUSIONS 198 FUTURE WORK 201 APPENDIX: GAUSSIAN MODEL 203 REFERENCES 207 7 UST OF FIGURES Figure 1.1: Energy diagram for a typical organic molecule' 19 Figure 1.2: Decays pathways for an excited organic molecule 20 Figure 1.3: Photooxidation of 7-(dialkylamino)-4-methyIcoumarin 36 Figure 1.4: Structure of a pyrromethene-BFi complex ^ 37 Figure 2.1 Structure of coumarin dyes: (a) Coum (b) derCoum (c) 2derCoum (d) 2Coum (e) derPCoum (f) 2derPCoum 43 Figure 2.2: Structure ofPyrromethene 567 44 Figure 2.3: Structure of silanol terminated PDMS (n=6-8) 46 Figure 2.4a: Synthetic Route 1: Xerogel Films 49 Figure 2.4b: Synthetic Route 2: Neat Films 50 Figure 2.4c; Synthetic Route 3: Polyceram Acid Route 51 Figure 2.4d: Synthetic Route 4: Polyceram Acid/Base Route: Non Synersis 52 Figure 2.4e: Synthetic Route 5: Polyceram Acid/Base: Synersis 53 Figure 2.4f: Synthetic Route 6: 3AS Polycerams 54 Figure 2.5: Photostability measurement setup 56 Figure 2.6: Photostability setup using a Nd:YAG laser pump 57 Figure 3.1: FTIR spectra of (a) TEOS and (b) derCoum at different hydrolysis times.... 62 Figure 3.2: Hydrolysis rate of TEOS and the silylated coumarin dyes 63 Figure 3.3: Ball and stick model of derCoum in its lowest energy form 64 Figure 3.4: Dye extraction of derCoum and Coum xerogel films at r=0.10 synthesized by Route 1 66 Figure 3.5: Dye extraction of derCoum xerogel films at r=0.10 synthesized by Route 1 with various TM0S:H20 ratios 67 8 Figure 3.6: Dye extraction of Coum xerogel films at r=0.05 synthesized by Route 1 with various