UNIVERSITY OF CALIFORNIA, SAN DIEGO Design and Optimization of Polymeric Silole and Boronate Photoluminescent Probes for Improved Explosives Detection Applications A Dissertation submitted in partial satisfaction of the requirements for the degree Doctor of Philosophy in Chemistry by Jason C. Sanchez Committee in charge: Professor William C. Trogler, Chair Professor Seth Cohen Professor David Hendrickson Professor Andrew Kummel Professor Yuhwa Lo 2008 Copyright© Jason C. Sanchez, 2008 All rights reserved The dissertation of Jason C. Sanchez is approved, and it is acceptable in quality and form for publication on microfilm. Chair University of California, San Diego 2008 iii DEDICATION For my wife Erin who brings true happiness to my life and is a constant reminder of how lucky I really am. For our baby boy that she carries inside her, no need for self- motivation now! For my parents who continue to make life easy for us and set a positive example for our family. For my sisters who find a way everyday to make me a proud brother. For my grandparents who give more than they have, take less then they should, and understand the meaning family. iv TABLE OF CONTENTS Signature Page..............................................................................................................iii Dedication.....................................................................................................................iv Table of Contents...........................................................................................................v List of Symbols and Abbreviations............................................................................xiii List of Figures...........................................................................................................xviii List of Schemes..........................................................................................................xxv List of Tables.............................................................................................................xxii Acknowledgements....................................................................................................xxx Vita, publications, and patents................................................................................xxxiii Abstract of the Dissertation....................................................................................xxxvi Chapter I Review of Polycarbosilanes, Catalytic Hydrosilylation, and Current Explosives Detection Applications.............................................................................1 1.1 Polycarbosilanes...................................................................................................2 1.1.1 Electronic Properties of Silicon…..................................................................2 1.1.2 Synthesis of Polycarbosilanes…….................................................................3 1.1.3 Electronic Delocalization in Polycarbosilanes................................................5 1.2 Hydrosilylation Catalysts and Mechanisms…......................................................5 1.3 Poly(silyl-vinylene)s...........................................................................................11 1.3.1 Optimization of Reaction Conditions...........................................................11 1.3.2 Photoactive Polymers....................................................................................14 v 1.3.3 Catalyst Modification....................................................................................14 1.3.4 Applications..................................................................................................17 1.4 Polysiloles...........................................................................................................18 1.4.1 Introduction to Siloles...................................................................................18 1.4.2 Polymerization Methods...............................................................................19 1.5 Explosives Detection Using Luminescent Sensors.............................................20 1.5.1 Targeted Explosive Analytes…....................................................................20 1.5.2 Improving Sensor Properties.........................................................................22 1.5.2.1 Particle Sampling....................................................................................24 1.5.3 Luminescent Polymer Sensors......................................................................25 1.6 Objectives of the Dissertation.............................................................................28 1.7 Acknowledgements.............................................................................................31 1.8 References...........................................................................................................32 Chapter II Synthesis, Characterization, and Evaluation 1,1-Tetraphenylsilole- and 1,1-Silafluorene-vinylene Polymers for Explosives Detection..........................41 2.1 Abstract...............................................................................................................42 2.2 Introduction.........................................................................................................44 2.3 Results and Discussion.......................................................................................48 2.3.1 Model Compounds........................................................................................48 2.3.2 Polymerizations.............................................................................................52 2.3.3 Photoluminescence.......................................................................................54 2.3.3.1 Solution-phase Photoluminescence........................................................54 vi 2.3.3.2 Solid-state Photoluminescence...............................................................56 2.3.3.3 Solution-phase Quantum Efficiencies of Fluorescence..........................59 2.3.4 Explosives Detection by Fluorescence Quenching.......................................60 2.3.4.1 Solution-phase Stern–Volmer Analysis..................................................60 2.3.4.2 Probing Explosive Analyte Binding by 29Si NMR.................................62 2.3.4.3 Surface Detection of Explosive Particulates...........................................74 2.3.4.4 Theoretical Calculations.........................................................................78 2.3.4.5 Detection Interferents..............................................................................81 2.4 Conclusions.........................................................................................................82 2.5 Experimental.......................................................................................................83 2.5.1 General Synthetic Techniques......................................................................83 2.5.2 29Si NMR Data..............................................................................................84 2.5.3 X-ray Crystal Structure Determination.........................................................85 2.5.4 Theoretical Methods.....................................................................................86 2.5.5 Solid-state Explosives Detection..................................................................87 2.5.6 Synthesis of 1,1-diethynylsilafluorene (DESF)............................................88 2.5.7 Synthesis of Methyl(tetraphenyl)silole-vinylene Trimer..............................89 2.5.8 Synthesis of Methyl(tetraphenyl)silole-silafluorene-vinylene Cotrimer......89 2.5.9 Synthesis of Methylsilafluorene-vinylene Trimer........................................90 2.5.10 Synthesis of Poly(tetraphenyl)silole-vinylene............................................90 2.5.11 Synthesis of Poly(tetraphenyl)silole-silafluorene-vinylene........................91 2.5.12 Synthesis of Poly(silafluorene-vinylene)....................................................91 vii 2.5.13 Synthesis of 1-methyl-1-vinyl(tetraphenyl)silole.......................................92 2.5.14 Synthesis of 1-methyl-1-vinylsilafluorene..................................................92 2.6 Acknowledgements.............................................................................................94 2.7 Appendix............................................................................................................95 2.8 References...........................................................................................................99 Chapter III Divinylbenzene Bridged Silole and Silafluorene Polymers. Improved Applications to Surface Imaging of Explosive Particulates...................................105 3.1 Abstract.............................................................................................................106 3.2 Introduction.......................................................................................................107 3.3 Results and Discussion.....................................................................................111 3.3.1 Model Compounds......................................................................................111 3.3.2 Catalyst Optimization and Polymerization.................................................117 3.3.3 Photoluminescence.....................................................................................119 3.3.3.1 Solution-phase