Extended arm polyphenylene dendrimers [Elektronische Ressource] : synthesis and characterization / vorgelegt von Ekaterina Vladimirovna Andreitchenko

Katya

Informations

• Publié par: johannes_gutenberg-universitat_mainz
• Publié le: 01 janvier 2006
• Nombre de lectures: 19
• Langue: English
• Poids de l'ouvrage: 6 Mo

Extrait

Extended Arm Polyphenylene Dendrimers:

Synthesis and Characterization




Dissertation zur Erlangung des Grades
‚‚Doktor der Naturwissenschaften’’
am Fachbereich Chemie und Pharmazie
der Johannes Gutenberg-Universität in Mainz

vorgelegt von



Ekaterina Vladimirovna Andreitchenko
geb. in Sankt-Petersburg, Russland














Mainz, 2006


Die vorliegende Arbeit wurde in der Zeit von Mai 2002 bis November 2005 am Max-Planck-
Institut für Polymerforschung in Mainz unter der Leitung von Prof. Dr. K. Müllen
durchgeführt.





























Herrn Professor Dr. K. Müllen danke ich für die sehr interessante Themenstellung and für
seine wissenschaftliche Förderung.
Contents

1 Introduction

1.1 The dendrimer concept 1
1.2 Chemical synthesis of dendrimers 2
1.3 Flexible dendrimers 5
1.4 Molecular structure 5
1.5 Properties of dendritic macromolecules compared to linear polymers 7
1.6 Rigid dendrimers 8
1.7 Synthesis of polyphenylene dendrimers through Diels-Alder cycloaddition 10
1.7.1 Divergent synthesis 12
1.7.2 Convergent synthesis 12
1.8 The influence of the cores and the branching units on the shape of the polyphe-
nylene dendrimers 15
1.9 Functionalization of polyphenylene dendrimers 16
a) Prior group introduction, the cyclopentadienone route 17
b) Posteriori Group Introduction 19
c) Electrophilic Aromatic Substitution 19
1.10 Practical applications of dendrimers 20
1.11 Motivation 21
1.12 Literature for Chapter 1 24


2 Extended Arm Polyphenylene Dendrimers

2.1 Introduction 28
2.2 Synthesis of the new branching unit 2.1 bearing tris-(para-phenylene ethynylene)arms 28
2.3 Synthesis of the new extended arm branching unit 3.1 30
2.4 The synthesis of ''exploded'' dendrimers up to the sixth generation 35
2.5 MALDI-TOF MS applied to the extended dendrimers 38
12.6 H NMR analysis of exploded dendrimers 49
2.7 Size exclusion chromatography (SEC) 52
2.8 Multi-angle laser light scattering size exclusion chromatography (MALLS-SEC) 62
2.9 Vibrational spectroscopy (IR/Raman) 63
2.10 Visualisation of the exploded dendrimers by structural simulation 64
2.11 Dynamic light scattering (DLS) 65
2.12 Transmission electron microscopy (TEM) 68
2.13 Atomic Force Microscopy (AFM) 74
2.14 Guest molecules and their monitoring by the quartz microbalance (QMB) technique 81
2.15 Shortening the arms slightly: ‘‘semi-extended’’ dendrimers bearing a
biphenyl - instead of a terphenyl spacer 87
2.16 Characterization of the dendrimers with biphenyl spacer 90
2.17 Outlook: dendrimers with biphenyl spacers for future application 92
2.18 Literature for Chapter 2 95


3 Synthesis and Hydrogenation of Dendrimers possessing internal -C≡C-
Triple bonds

3.1 Introduction 101
3.2 Synthesis of new cyclopentadienone branching unit bearing the para-phenylene
ethynylene arms (5.1) 101
3.3 Synthesis of the first-generation dendrimer with branching unit 5.1 104
3.4 Synthesis of the second- and third-generation dendrimers bearing eight internal
triple bonds 108
3.5 Heterogeneous catalysis of hydrogenation: some principal considerations 110
3.6 Hydrogenation of the second-generation dendrimer 5.6 113
3.7 Hydrogenation of the third-generation dendrimer 5.7 116
3.8 Further effects caused by hydrogenation of internal -C≡C- triple bond
3.8.1 UV-Vis absorption of the second- and third-generation dendrimers 118
3.8.2 Raman spectroscopy of the third-generation dendrimers 5.7 and 5.9 119
3.8.3 Diffusion-ordered 2D NMR (DOSY) of the third-generation
dendrimers 5.7 and 5.9 120
3.8.4 Incorporation of guest molecules 122
3.9 Literature for Chapter 3 123

4 Dendronization of a Chromophore Core by means of the New Extended
Arm 3.1

4.1 Introduction 125
4.2 Synthesis of dendronized perylene dyes using the branching unit 3.1 127
4.3 Characterization of dendronized chromophore dendrimers 6.5-6.10 130
4.4 Optical properties
4.4.1 Absorption and emission 132
4.4.2 Fluorescence quenching experiment 135
4.4.3 Fluorescence correlation spectroscopy (FCS) 137
4.5 Literature for Chapter 4 145


5 Summary 147


6 Experimental Part

6.1 Reagents and solvents 158
6.2 Instruments and analysis 159
6.3 General procedures 161
6.4 Synthesis of the extended arm polyphenylene dendrimers (for Chapter 2) 162
6.5 Synthesis of the semi-extended arm polyphenylene dendrimers (for Chapter 2) 178
6.6 Synthesis of the dendrimers possessing eight inner -C≡C- triple bonds and
their hydrogenation (for Chapter 3) 185
6.7 Synthesis of the extended arm polyphenylene dendrimers with perylenedimide core
(for Chapter 4) 195
6.8 Literature for Chapter 6 200





Abbreviations
AFM atomic force microscopy
Calcd. calculated
Da Dalton
DLS dynamic light scattering
DOSY diffusion-ordered (NMR spectrum)
EDA ethylenediamine
FD MS field desorption mass spectrometry
G1-G6 first-sixth generation number
HPLC high performance liquid chromatography
IR infrared
MALDI-TOF matrix assisted laser desorption ionization time of flight (MS)
MALLS multiple angle laser light scattering
MS mass spectrometry
M number average molecular weight n
M weight average molecular weight w
M molecular weight (calculated molecular mass)
NMR nuclear magnetic resonance
PAMAM poly-(amino amine)
PDI 1) poly-dispersity index, 2) perylene-3,4,9,10-tetracarboxdimides
PDs polyphenylene dendrimers
PS poly-(styrene)
RI refractive index
R retention factor F
r.t. room temperature
SEC size exclusion chromatography
TBAF tetrabutylammoniumfluoride trihyrate
Td tetraphenylmethane core
TEM transmission electron microscopy
THF tetrahydrofuran
TiPS triisopropylsilyl group
UV-Vis ultraviolet-visible (light)
QMB quartz microbalance

Introduction Chapter 1

1 Introduction

1.1 The dendrimer concept

1-3]Traditional polymers, according to Staudinger, may be divided into three major
macromolecular architectures: (I) linear (plexiglass, nylon), (II) cross-linked (rubber,
expoxies), and (III) branched (low density polyethylene). As the fourth major of
macromolecular architecture dendritic polymers have evolved; they consist of four sub-
[3-4] [3] [3] [3,5]categories: random hyperbranched, dendigraftes, dendrons, and dendrimers. The
present dissertation is concerned with the last category, namely that of dendrimers,
exclusively.
A dendrimer is generally described as a macromolecule, which is characterized by its
extensively branched 3D structure that provides a high degree of surface functionality and
versatility. Its structure is always built around a central multi-functional core molecule, with
branches and end-groups. Dendrimers are synthesised in a stepwise manner, i.e. each
successive shell, known as a generation, is formed in an individual step.

In 1978 Vögtle and co-workers reported the first preparation, separation and mass
[5-6]spectrometric characterization of a basic dendrimer structure. These authors produced a
cascade in an iterative sequence of reaction steps, in which each additional reaction gave a
higher generation material (Scheme 1.1). The reaction of a monoamine 1.1, as a starting
material, with acrylonitrile via Michael addition led to the synthesis of desired dinitrile 1.2-A
which was reduced to the terminal diamine 1.2-B, serving as a branching unit. Then the
molecule 1.2-B was subjected to the same reaction sequence to generate a heptaamine. This
was the first synthesis of a cascade molecule and during the 1980’s only a handful of
[5]additional research papers on cascade molecules were published.
CN CN
CN CH NHCN 2 2 CN N N
Red.