Polyphenylene Dendrimers - Design and Synthesis of Monodisperse Functional Nanoparticles Dissertation zur Erlangung des Grades "Doktor der Wissenschaften" am Fachbereich Chemie und Pharmazie der Johannes Gutenberg-Universität in Mainz vorgelegt von Stefan Bernhardt geb. in Hofheim a. Ts. Mainz 2005 Dekan: Herr Prof. Dr. P. Langguth 1. Berichterstatter: 2. Berichterstatter: Tag der mündlichen Prüfung: 26.06.2006 Die vorliegende Arbeit wurde in der Zeit von März 2002 bis März 2005 am Max-Planck- Institut für Polymerforschung in Mainz unter Anleitung von Herrn Prof. Dr. K. Müllen durchgeführt. Dedicated to my wife If we knew what we were doing it wouldn't be research. Einstein, Albert Index of Abbreviations: AFM atomic force microscopy Anal. analysis calcd. calculated TBAF tetrabutylammoniumfluoride-hexahydrate CD2Cl2 deuterated methylenechloride δ chemical shift / ppm d doublet d8THF deuterated tetrahydrofuran DEE diethylether DMF dimethylformamide DMSO dimethylsulfoxide eq. equivalent EtOH ethanol FD field desorption G1, G2, G3, first-, second-, and third-dendrimer generation GS ground state h hours J coupling constant / Hz LE locally-excited state m multiplett m / g weight in gram MALDI-TOF matrix-assisted laser desorption/ionization-time of flight MCH methylcyclohexane MeOH methanol MS mass spectrometry n refractive index NMR nuclear magnetic resonance PE petroleum ether, low boiling PMI perylene monoimide PPh3 triphenylphosphine ppm parts per million (chemical shift in NMR spectroscopy) RT room temperature s singulet SM single molecule T temperature / °K or °C t triplet TCSPC time-correlated single photon counting TEA triethylamine THF tetrahydrofuran TIPS tri-iso-propylsilyl TPA triphenylamine UV ultraviolett Фflu fluorescence quantum yield τflu decay time of fluorescence kfwd and krev forward and reverse electron transfer rate constants CS charge-separated state Table of contents 1 INTRODUCTION................................................................................................. 1 1.1 Dendrimer Chemistry, a Short Overview............................................................................................. 1 1.1.1 Linear Building Blocks ........................................................................................................................ 3 1.1.2 Branched Building Blocks ................................................................................................................... 4 1.2 Polyphenylene Dendrimers .................................................................................................................... 5 1.3 Synthesis of Polyphenylene Dendrimers............................................................................................... 6 1.3.1 Palladium Catalysed Aryl-Aryl Coupling Reactions ........................................................................... 6 1.3.2 Diels-Alder Cycloaddition ................................................................................................................... 7 1.3.2.1 Divergent Synthesis.................................................................................................................... 8 1.3.2.2 Convergent Synthesis ................................................................................................................. 9 1.4 Diversification of Shape........................................................................................................................ 10 1.4.1 Core.................................................................................................................................................... 10 1.4.2 Branching Units ................................................................................................................................. 11 1.5 Shape Persistence.................................................................................................................................. 12 1.5.1 Solid-State NMR................................................................................................................................ 12 1.5.2 PFM-AFM Measurements ................................................................................................................. 13 1.5.3 SANS Experiments ............................................................................................................................ 13 1.6 Functionalization .................................................................................................................................. 13 1.6.1 Postsynthetic ...................................................................................................................................... 14 1.6.2 Presynthetic........................................................................................................................................ 15 1.7 Nomenclature ........................................................................................................................................ 15 1.8 Motivation ............................................................................................................................................. 16 1.9 References.............................................................................................................................................. 16 2 PYRENE AS CHROMOPHORE AND ELECTROPHORE - ENCAPSULATION IN A RIGID POLYPHENYLENE SHELL .................................................................. 18 2.1 Introduction .......................................................................................................................................... 18 2.2 Synthesis of Dendronized Pyrenes....................................................................................................... 24 2.2.1 Synthesis of the Pyrene Core 1,3,6,8-Tetraethynyl-pyrene................................................................ 24 2.2.2 Synthesis of First- to Fourth-Generation Dendronized Pyrenes......................................................... 24 2.2.3 Improving the Film Forming Ability ................................................................................................. 27 2.2.4 Dendronized Pyrenes with a Higher Symmetry................................................................................. 28 2.2.5 Modification of the Pyrene Core – Toward New Dendrimer Shapes................................................. 29 2.3 Characterization of the Cores and the According Dendrimers ........................................................ 32 2.3.1 Characterization of the Cores............................................................................................................. 32 2.3.2 Characterization of the Dendrimers ................................................................................................... 33 2.4 Visualization and Simulation............................................................................................................... 35 2.4.1 Crystal Structure of a First-Generation Dendrimer............................................................................ 35 2.4.2 Molecular Modeling........................................................................................................................... 36 2.5 Pyrene as Chromophore....................................................................................................................... 39 2.5.1 Absorption and Emission in Solution ................................................................................................ 39 2.5.2 Absorption and Emission in Solid-State ............................................................................................ 43 2.5.3 Fluorescence Quenching Experiments............................................................................................... 45 2.5.4 Temperature Dependent Fluorescence Spectroscopy......................................................................... 47 2.6 Pyrene as Electrophore ........................................................................................................................ 49 2.6.1 Reduction of Dendronized Pyrenes on a Potassium Mirror ............................................................... 49 2.6.2 Electrochemical Studies..................................................................................................................... 52 2.7 Organic Light-Emitting Diodes ........................................................................................................... 54 2.8 Conclusion ............................................................................................................................................. 56 2.9 References.............................................................................................................................................. 58 3 BENZOPHENONE FUNCTIONALIZED POLY-PHENYLENE DENDRIMERS – FROM INSIDE TO OUTSIDE ................................................................................... 62 3.1 Introduction .......................................................................................................................................... 62 3.2 Multiple Benzophenones in the Dendrimer Backbone ...................................................................... 67 3.2.1 Synthesis of the Branching Reagent .................................................................................................. 67 3.2.2 Synthesis of the Dendrimers .............................................................................................................