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Group Heterocycles for Semiconducting Polymers Main Group Heterocycles for Semiconducting Polymers Dissertation zur Erlangung des Doktorgrades der Mathematisch-Naturwissenschaftlichen Fakultät der Christian-Albrechts-Universität zu Kiel vorgelegt von Julian Linshöft Kiel 2014 1. Gutachterin: Prof. Dr. Anne Staubitz 2. Gutachter: Prof. Dr. Ulrich Lüning Tag der mündlichen Prüfung: 24. November 2014 Zum Druck genehmigt: 24. November 2014 gez. Prof. Dr. Wolfgang J. Duschl, Dekan Die vorliegende Arbeit wurde unter Anleitung von Prof. Dr. Anne Staubitz am Otto-Diels-Institut für Organische Chemie der Christian-Albrechts-Universität zu Kiel in der Zeit von Mai 2011 bis Oktober 2014 angefertigt. Hiermit erkläre ich, Julian Linshöft, an Eides statt, dass ich die vorliegende Dissertation selbstständig und nur mit den angegebenen Hilfsmitteln angefertigt habe. Inhalt und Form dieser Arbeit sind, abgesehen von der Beratung durch meine Betreuerin Prof. Dr. Anne Staubitz, durch mich eigenständig erarbeitet und verfasst worden. Die Arbeit entstand unter Einhaltung der Regeln guter wissenschaftlicher Praxis der Deutschen Forschungsgemeinschaft. Weder die gesamte Arbeit noch Teile davon habe ich an anderer Stelle im Rahmen eines Prüfungsverfahrens eingereicht. Dies ist mein erster Promotionsversuch. Kiel, den 2. Oktober 2014 ________________________________ (Julian Linshöft) Danksagung An dieser Stelle möchte ich mich bei all denen bedanken, die dazu beigetragen haben, dass ich diese Arbeit fertigstellen konnte. Dazu gehört an erster Stelle die Unterstützung, die in direktem Zusammenhang zu dieser Arbeit steht: Vielen Dank an Prof. Dr. Anne Staubitz! Danke für das spannende und fordernde Thema sowie die ausgezeichnete und immer sehr engagierte Betreuung und Beratung. Vielen Dank für das Vertrauen in mich und all die gewährten Freiheiten. Ein großes Dankeschön geht auch an die Deutsche Bundesstiftung Umwelt (DBU), die meine Promotion über 3 Jahre finanziert hat. Die Seminare (und die Verleihungen der Umweltpreise, Woche der Umwelt, …) jedes Jahr waren nicht nur sehr lehrreich, sondern haben wirklich viel Spaß gebracht und ich habe viele nette Menschen kennengelernt. Prof. Dr. Ulrich Lüning möchte ich für die Übernahme des Zweitgutachtens danken. Diese Arbeit wäre außerdem nicht möglich gewesen ohne die Mitarbeiter dieses Instituts: Danke, dass ihr immer so bereitwillig und hervorragend geholfen habt, auch wenn man mal bei einem „Spezialfall“ Hilfe benötigte. Vielen Dank an Prof. Dr. Frank Sönnichsen für die Hilfe bei dem einen oder anderen verwirrenden Spektrum, und dafür, dass Sie immer bereitwillig neue Kerne eingerichtet haben. Danke an die gesamte spektroskopische Abteilung für die Messungen all dieser Spektren! Vielen Dank auch an Prof. Dr. Christian Näther und seine Mitarbeiter für die Röntgenstrukturanalysen. Ich danke außerdem Tobias Tellkamp für das Korrekturlesen dieser Arbeit. I would like to thank Dr. Paul Gates for all the high resolution mass spectra. Many thanks to my interns Stephan Segler, Evan Baum, Andreas Hussain and Nils Lüdecke: thanks for all your work and the fun time we spent together! Den gesamten Arbeitskreisen Staubitz und Sönnichsen danke ich für die sehr schöne und witzige Zeit, die wir beim Arbeiten, beim Essen und auch zwischendurch miteinander verbracht haben. Meiner Laborkollegin Annika Heinrich möchte ich zusätzlich für die sehr gute Zusammenarbeit über all die Jahre in unserem kleinen Labor danken. Viele Leute haben mich auch eher indirekt beim Gelingen dieser Arbeit unterstützt: immer wenn ich Abwechslung brauchte, habt ihr für sie gesorgt – und zum Glück auch dann, wenn man eigentlich gar keine Abwechslung brauchte :) Vielen lieben Dank an meine Freunde für die wundervolle Zeit! Danke an meine Familie für den Rückhalt und das Verständnis, wenn ich mal keine Zeit für euch hatte. Grace, ich habe keine Ahnung, wer ich wäre, wo ich wäre und wie ich wäre, wenn ich dich nicht (kennengelernt) hätte. Vielen Dank, dass ich es nicht herausfinden musste :) Achja, und vielen Dank an den/die Mitarbeiter/in aus dem Studierendensekretariat: hätten Sie damals nicht so eine nette Antwortkarte geschrieben, dass meine Bewerbungsunterlagen für den Studiengang gut angekommen sind, hätte ich vielleicht einen anderen Studienort gewählt. Zusammenfassung In dieser Arbeit wurde das Konzept der Nucleophil-selektiven Kreuzkupplung entwickelt und auf Thiophen, welches ein klassischer Baustein für halbleitende Polymere ist, angewendet. Zwei Metallfunktionalitäten unterschiedlicher Reaktivität wurden an den Heteroaromaten angebracht - eine Zinn-Gruppe und ein Borester. Diese neue Verbindung ermöglichte Nucleophil-selektive Kreuzkupplungsreaktionen in hohen Ausbeuten: Im ersten Schritt läuft die Stille-Reaktion ab, während im zweiten Schritt nach der Zugabe eines weiteren Elektrophils, Wasser und einer Base die Suzuki-Kreuzkupplung stattfindet. Die Vielseitigkeit der Reaktion wurde an Hand von elektronenneutralen, elektronenreichen und elektronenarmen Elektrophilen gezeigt. Polymerisation Eine Syntheseroute zu Stannolmonomeren des AA-Typs wurde entwickelt und das erste stannolhaltige halbleitende Polymer wurde hergestellt. Für die Polymerisation wurde die Stille- Kreuzkupplung verwendet, wobei das Problem, dass der Stannolring unter diesen Reaktionsbedingungen reagieren könnte, durch sterische Abschirmung des Stannolrings verhindert wurde. Dies führte zu einer Nucleophil-selektiven Kreuzkupplung, die zwischen zwei Zinnfunktionalitäten unterscheiden kann. Der Erfolg der Polymerisation wurde durch NMR- Spektroskopie, MALDI Massenspektrometrie, GPC und UV/Vis Messungen bestätigt. Die Stannole haben sich als Heterocyclen mit einem hohen Potential für halbleitende Polymere herausgestellt, da sie starke bathochrome Verschiebungen in den Absorptionsspektren zeigen. Ein Stannolmonomer vom AB-Typ wurde für eine Kettenwachstumspolymerisation hergestellt und polymerisiert. Das erhaltene Polymer war schwerlöslich und eine Untersuchung der Kinetik war nicht möglich. Wichtige Schritte auf dem Weg zum ersten Polymer mit einem antiaromatischen Borol wurden unternommen. Hierfür wurde ein stark abgeschirmtes Zirconacyclopentadien regioselektiv hergestellt. Abstract The concept of nucleophile selective cross-coupling reactions was developed for thiophene, a motif that is typically used in semiconducting polymers. Two metal functional groups of different reactivity were attached to the heteroaromatic compound, a stannyl group and a boronic ester. This new compound allowed high yielding, fully nucleophile selective cross-coupling reactions, where the Stille reaction occurs first, and in a second step, after adding another electrophile, water and a base, the Suzuki cross-coupling reaction takes place. The versatility of the reaction was shown with electron rich, electron neutral and electron poor electrophiles. Polymerization A synthetic route to AA-type stannole monomers was developed, and the first stannole containing semiconducting polymer was synthesized. The Stille cross-coupling reaction was used for the polymerization, and the problem that the stannole ring could react under these conditions was eliminated by steric shielding of the stannole ring. This led to nucleophile selective cross-coupling reactions that distinguish between two stannyl functionalities. The success of the polymerization was proved by NMR spectroscopy, MALDI spectrometry, GPC and UV/Vis measurements. The stannoles have a high potential as heterocycles for semiconducting polymers, as they caused strong bathochromic shifts in the absorption spectra. An AB-type stannole monomer for a polymerization that may proceed via a chain-growth mechanism was developed and polymerized. The obtained polymer was poorly soluble and an investigation of the kinetics was impossible. Major steps on the way to the first polymer containing an antiaromatic borole were undertaken. For this purpose, the regioselective formation of a highly shielded zirconacyclopentadiene was achieved. Abbreviations ATR attenuated total reflectance calcd. calculated COSY correlated spectroscopy Cp cyclopentadienyl CV column volume d doublet (NMR) DCM dichloromethane DMF dimethylformamide DMSO dimethyl sulfoxide EI electron ionization ESI electrospray ionization FT Fourier transform GPC gel permeation chromatography HH head-to-head HMBC heteronuclear multiple bond coherence HOMO highest occupied molecular orbital HRMS high resolution mass spectrometry HSQC heteronuclear single quantum coherence HT head-to-tail IR infrared LDA lithium diisopropylamide LUMO lowest unoccupied molecular orbital m medium (concerning the intensity) (IR) m multiplet (NMR) M.p. melting point MALDI matrix-assisted laser desorption/ionization MW microwave NIS N-iodosuccinimide NMR nuclear magnetic resonance OFET organic field effect transistor OLED organic light emitting diode ORTEP oak ridge thermal ellipsoid plot OSC organic solar cell P3AT poly(3-alkyl)thiophene PA polyacetylene PDI polydispersity index PE polyethylene PEDOT polyethylene dioxythiophene PPP polyparaphenylene PPV polyparaphenylene vinylene PPy polypyrrole pyr pyridine Rf retardation factor RFID radio frequency identification rr regioregular s strong (concerning the intensity) (IR) s singlet (NMR) TEA triethylamine THF tetrahydrofuran TLC thin layer chromatography TMS tetramethylsilane TOF time-of-flight TT tail-to-tail UV ultraviolet Vis visible Abbreviations for building blocks in polymer names: B benzothiadiazole St stannole T thiophene A Guide to this Thesis This thesis is divided into 5 chapters (see table of contents).
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