présentée pour obtenir le grade de

THESE
présentée pour obtenir le grade de
DOCTEUR DE L’UNIVERSITE LOUIS PASTEUR
DE STRASBOURG
par
Sylvestre BONNET
2+Ru(terpy)(phen)(L) complexes as a new tool
towards light-controlled molecular machines.
Photoinduced ligand substitution reactions,
photoisomerisation and inclusion in a molecular ring.
Soutenue le 27 septembre 2005 devant la Commission d’examen
Prof. Mir Wais HOSSEINI Président du jury
Prof. Dr. Gerard van KOTEN Rapporteur
Dr. Bruno CHAUDRET
Dr. Jean-Paul COLLIN Co-Directeur de Thèse
Dr. Jean-Pierre SAUVAGEThèse de S. Bonnet
2Thèse de S. Bonnet
présentée pour obtenir le grade de
DOCTEUR DE L’UNIVERSITE LOUIS PASTEUR
DE STRASBOURG
2+Les complexes Ru(terpy)(phen)(L)  : un nouvel outil
pour la construction de machines moléculaires
activées par la lumière.
Photosubstitution de ligands, photoisomérisation,
inclusion dans un anneau.
Soutenue le 27 septembre 2005 devant la Commission d’examen
Prof. Mir Wais HOSSEINI Président du jury
Prof. Dr. Gerard van KOTEN Rapporteur
Dr. Bruno CHAUDRET
Dr. Jean-Paul COLLIN Co-Directeur de Thèse
Dr. Jean-Pierre SAUVAGE
3Thèse de S. Bonnet
4Thèse de S. Bonnet
SOMMAIRE
SOMMAIRE.............................................................................................................................................................................. 5
REMERCIEMENTS ................................................................................................................................................................ 9
GENERAL INTRODUCTION ............................................................................................................................................. 13
I. NATURAL MOLECULAR MACHINES ................................................................................................................................... 13
I.1. Motion in living systems........................................................................................................................................... 13
I.2. A rotating molecular motor: ATPase....................................................................................................................... 14
I.3. Brownian motion in natural molecular machines................................................................................................... 15
I.4. The role of organisation in the use of mechanical energy...................................................................................... 16
II. ARTIFICIAL MOLECULAR MACHINERY............................................................................................................................. 18
II.1. Definitions ............................................................................................................................................................... 18
II.2. How to control motion at the molecular level........................................................................................................ 19
III. ROTAXANES AND CATENANES AS CENTRAL BUILDING BLOCKS OF ARTIFICIAL MOLECULAR MACHINES .................... 20
III.1. Definitions.............................................................................................................................................................. 20
III.2. Application of catenanes and rotaxanes to molecular machines......................................................................... 21
III.3. An alternative: scorpionate molecules.................................................................................................................. 22
IV. EXAMPLES OF ARTIFICIAL MOLECULAR MACHINES....................................................................................................... 22
IV.1. Machines based on donor-acceptor interactions.................................................................................................. 22
IV.1.a. Hydrogen-bond interactions .............................................................................................................................................. 22
IV.1.b. Charge transfer interactions............................................................................................................................................... 23
IV.2. Machines based on photoinduced geometrical rearrangements.......................................................................... 24
IV.2.a. Cis-trans isomerisation of azobenzene.............................................................................................................................. 24
IV.2.b. Cis-trans isomerisation of C=C double bonds.................................................................................................................. 24
IV.3. Machines based on preferred coordination modes............................................................................................... 26
IV.3.a. Cu(I) / Cu(II) redox systems.............................................................................................................................................. 26
IV.3.b. An artificial molecular muscle set in motion by ion exchange........................................................................................ 26
V. RUTHENIUM (II) POLYPYRIDYL COMPLEXES .................................................................................................................. 27
V.1. Photoreactivity......................................................................................................................................................... 27
V.2. Template syntheses.................................................................................................................................................. 29
V.3. Molecular machine prototypes based on ruthenium (II) photochemistry ............................................................. 30
VI. DESIGN OF THE PROJECT ................................................................................................................................................ 32
2+VI.1. Drawbacks of Ru(phen) (L) complexes.............................................................................................................. 322
VI.2. The work of Emma Schofield ................................................................................................................................. 33
VI.3. General overview of this PhD-thesis..................................................................................................................... 34
N+CHAPTER 1: SYNTHESIS OF RU(TERPY)(PHEN)(L) MODEL COMPLEXES AND LIGAND
SUBSTITUTION REACTIONS ........................................................................................................................................... 37
I. INTRODUCTION.................................................................................................................................................................. 37
N+II. SYNTHESIS AND CHARACTERISATION OF RU(TERPY*)(PHEN)(L) COMPLEXES ........................................................... 38
II.1. Synthesis of precursors ........................................................................................................................................... 38
II.2. Thermal ligand exchange reactions ....................................................................................................................... 40
II.2.a. Reactivity ............................................................................................................................................................................. 40
II.2.b. X-ray structures ................................................................................................................................................................... 40
n+II.2.c. Steric hindrance in Ru(terpy*)(phen)(L) where L is a substituted pyridine................................................................... 41
II.3. Photochemical ligand exchange reactions............................................................................................................. 42
n+II.3.a. Absorption spectroscopy of Ru(terpy*)(phen)(L) complexes......................................................................................... 42
II.3.b. Preparative scale reactions .................................................................................................................................................. 43
II.3.c. Kinetic studies by UV-vis absorption spectroscopy........................................................................................................... 43
II.3.d. NMR studies ........................................................................................................................................................................ 45
2+III. ENHANCEMENT OF THE PHOTOSUBSTITUTION EFFICIENCY IN RU(TERPY*)(N-N)(L) WHERE N-N IS A DIIMINE
BIDENTATE CHELATE ............................................................................................................................................................ 46
III.1. Synthesis of complexes with a crowded coordination sphere .............................................................................. 47
III.2. Enhanced photoreactivity with a hindered bidentate chelate .............................................................................. 48
III.2.a. Absorption spectroscopy...................................................