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Second coordination sphere effects in [FeFe]-Hydrogenase mimics

Zaffaroni, R.

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Citation for published version (APA):Zaffaroni, R. (2017). Second coordination sphere effects in [FeFe]-Hydrogenase mimics

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Download date: 21 Nov 2018

Second coordination sphere effects in [FeFe]-Hydrogenase mimics

Cover design and artistic images by Riccardo Zaffaroni and Ilenia Galia

ISBN 978-94-6295-507-3

Printed by ProefschriftMaken | www.proefschriftmaken.nl

Second coordination sphere effects in [FeFe]-Hydrogenase mimics

ACADEMISCH PROEFSCHRIFT

ter verkrijging van de graad van doctor

aan de Universiteit van Amsterdam

op gezag van de Rector Magnificus

prof. dr. ir. K.I.J. Maex

ten overstaan van een door het College voor Promoties ingestelde commissie,

in het openbaar te verdedigen in de Agnietenkapel

op donderdag 22 juni 2017, te 12:00 uur

door

Riccardo Zaffaronigeboren te Como, Italië

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Promotiecommissie

Promotor: prof. dr. J.N.H. Reek Universiteit van Amsterdam

Copromotores: dr. ir. J.I. van der Vlugt Universiteit van Amsterdam

dr. R.J. Detz Universiteit van Amsterdam

Overige leden: prof. dr. B. de Bruin Universiteit van Amsterdam

prof. dr. T.B. Rauchfuss University of Illinois

prof. dr. E. Bouwman Universiteit van Leiden

prof. dr. M.T.M. Koper Universiteit van Leiden

prof. dr. J.H. van Maarseveen Universiteit van Amsterdam

prof. dr. S. Woutersen Universiteit van Amsterdam

Faculteit: Faculteit der Natuurwetenschappen, Wiskunde en Informatica

The research described in this thesis was performed at the Van ‘t Hoff Institute for Molecular Sciences, University of Amsterdam, the Netherlands.

This work is part of the research programme of the Foundation for Fundamental Research on Matter (FOM), which is part of the Netherlands Organisation for Scientific Research (NWO).

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he noblest pleasure is the joy of understanding T“ “Leonardo da Vinci

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Second coordination sphere effects

in [FeFe]-Hydrogenase mimics

Contents

Chapter 1. Introduction ............................................................................................. 1

The energy problem .................................................................................... 2 Natural photosynthesis .............................................................................. 3 Hydrogenases ................................................................................................. 5 Artificial photosynthesis ........................................................................... 8 Artificial photosynthesis devices ........................................................... 10 Molecular catalysts ...................................................................................... 14 Iron-Iron hydrogenase synthetic models ........................................... 17 Thesis layout................................................................................................... 23 References ....................................................................................................... 25

Chapter 2. Proton relay effect in pyridyl appended hydrogenase mimics 31

Introduction .................................................................................................... 32 Strategy ............................................................................................................. 34 Results and discussion ............................................................................... 36 Synthesis and characterization ........................................................ 36 Cyclic voltammetry studies in CH2Cl2 ............................................ 42 Reactivity of the complexes upon reduction .............................. 46 Proton reduction from weak acid in CH2Cl2................................ 51 Study of the complexes in CH2Cl2 with strong acid ................. 56 Catalysis in diluted H2SO4 ................................................................... 57 Conclusions ..................................................................................................... 61 Experimental .................................................................................................. 62 Appendix .......................................................................................................... 67 References ....................................................................................................... 70

Chapter 3. Hydrogenase mimics immobilized on FTO electrodes; a strategy towards solar fuel devices ............................................... 73

Introduction .................................................................................................... 74 Strategy ............................................................................................................. 75 Results and discussion ............................................................................... 76 Synthesis and characterization ........................................................ 76 Cyclic voltammetry studies in homogeneous solution .......... 80

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Second coordination sphere effects

in [FeFe]-Hydrogenase mimics

Electrochemical measurements of modified electrodes ....... 88 Conclusions ..................................................................................................... 93 Experimental .................................................................................................. 94 Appendix .......................................................................................................... 99 References ....................................................................................................... 102

Chapter 4. Fundamental studies of electron transfer processes across the rim of M12L24 nano-spheres .............................................. 105

Introduction .................................................................................................... 106 Strategy ............................................................................................................. 107 Results and discussion ............................................................................... 108 Synthesis and characterization of building blocks .................. 108 Preparation and characterization of M12L24 cages ................... 112 Electrochemistry .................................................................................... 118 Structural integrity of the supramolecular structure

of the cage upon the electrochemical event ............................... 128 Conclusions ..................................................................................................... 131 Experimental .................................................................................................. 132 Appendix .......................................................................................................... 145 References ....................................................................................................... 151

Chapter 5. Building charges in M12L24 nano-spheres. Does the Faraday principle still hold for molecular objects? .... 155

Introduction .................................................................................................... 156 Strategy ............................................................................................................. 157 Results and discussion ............................................................................... 158 Large size electrolyte synthesis ....................................................... 158 Samples preparation ............................................................................ 163 Electrochemistry .................................................................................... 164 Conclusions ..................................................................................................... 173 Experimental .................................................................................................. 174 Appendix .......................................................................................................... 178 References ....................................................................................................... 179

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Second coordination sphere effects

in [FeFe]-Hydrogenase mimics

Chapter 6. Proton preorganization effect in M12L24 nano-spheres containing hydrogenase mimics ........................................................ 183

Introduction .................................................................................................... 184 Strategy ............................................................................................................. 185 Results and discussion ............................................................................... 187 Synthesis and characterization of building blocks .................. 187 Preparation and characterization of M12L24 cages ................... 189 Electrochemistry .................................................................................... 195 Conclusions ..................................................................................................... 205 Experimental .................................................................................................. 206 References ....................................................................................................... 212

Summary ............................................................................................................................ 215

Samenvatting .................................................................................................................... 223

Acknowledgments ............................................................................................................... 231

About the author .................................................................................................................. 239

Dedicato a

Alessia

spiraglio di luce e supporto insostituibile in ogni singolo momento da otto anni ad oggi. Senza la tua presenza giornaliera, gli infiniti consigli, suggerimenti e vicinanza

sia nei momenti piacevoli che in quelli meno belli non avrei mai potuto arrivare a completare il PhD e nemmeno questo libro

grazie di essermi vicina ti amo

mamma

nessuno dei miei successi sarebbe stato possibile senza la tua costante motivazione grazie di aver riposto in me la tua fiducia spero in qualche modo di poterla ripagare

grazie di cuore