New routes towards supramolecular columnar assemblies [Elektronische Ressource] / Janis Lejnieks

Lejnieks_20110203135217

Informations

• Publié par: rheinisch-westfalischen_technischen_hochschule_-rwth-_aachen
• Publié le: 01 janvier 2011
• Nombre de lectures: 64
• Langue: English
• Poids de l'ouvrage: 7 Mo

Extrait

New routes towards supramolecular
columnar assemblies


Von der Fakultät für Mathematik, Informatik und Naturwissenschaften der RWTH Aachen
University zur Erlangung des akademischen Grades eines Doktors der Naturwissenshaften
genehmigte Dissertation


vorgelegt von

Master of Science
Jānis Lejnieks
aus Riga, Lettland



Berichter: Universitätsprofessor Dr. rer. nat. Martin Möller
Universitätsprofessor Dr. rer. nat. Andrij Pich


Tag der mündlichen Prüfung: 26.01.2011






Diese Dissertation ist auf den Internetseiten der Hochschulbibliotek online verfügbar



























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Maniem vecākiem

Dedicated to my Parents

3 Acknowledgment

I would like to thank Professor Dr. Martin Möller for giving me opportunity to do my PhD
work at DWI an der RWTH Aachen e.V. and Institute of Technical and Macromolecular
Chemistry, RWTH Aachen and giving me vast freedom in choosing research topics.

I am grateful Dr. Helmut Keul for direct, magnificent supervision of my PhD work.

I wish to thank Dr. Xiaomin Zhu for great discussions about liquid crystals.

I would like to thank Dr. Dimitri Ivanov and Denis Anokhin (Institut de Sciences des
Matériaux de Mulhouse, France) for synchrotron XRD analyis of my most interesting
compounds.

I wish to thank Dr. Aleksandra Bystrova, Jingbo Wang and Dr. Ahmed Mourran for SFM
measurements and interesting discussions concerning self-assembly.

Many thank to Cristian Vaida, Nicolas Pasquier, Vishal Goel and Yingchun He for excellent
NMR service.

I wish to thank Rainer Haas for excellent solving any technical problem in lab.

Though, many have not been mentioned, none is forgotten.







4 Publications:

1. Jānis Lejnieks, Ahmed Mourran, Xiaomin Zhu, Helmut Keul, Martin Möller, Denis
Anokhin, Dimitri Ivanov. Synthesis and Self-Assembly of Wedge-shaped Monodendrons
with L-Alanine at the Focal Point, manuscript

2. Jānis Lejnieks, Xiaomin Zhu, Jingbo Wang, Ahmed Mourran, Helmut Keul, Martin
Möller, Denis Anokhin, Dimitri Ivanov. Self-Assembly of a Low-Symmetry Monodendron
Containing Two Asymmetrically - Linked Molecular Wedges, ChemPhysChem 2010, 11,
3638 – 3644

3. Jānis Lejnieks, Ahmed Mourran, Walter Tillmann, Helmut Keul, Martin Möller. Thin film
of poly(acrylic acid-co-allyl acrylate) as sacrificial protective layer for hydrophilic self
cleaning glass. Materials 2010, 3(5), 3369-3384.























5
Content


Chapter 1 Introduction……………………………………………………………………...…9

Chapter 2 Self-assembly in thin films of wedge-shaped monodendrons functionalized with
L-alanine at the Focal Point ………………………………………………………………….15

Chapter 3 Self-assembly in bulk of wedge-shaped monodendrons functionalized with L-
alanine at the Focal Point……………………………………………………………………..37

Chapter 4 Synthesis of wedge-shaped monodendritic azlactone coupler………………...…50

Chapter 5 Self-Assembly of a Low-Symmetry Monodendron Containing Two
Asymmetrically-Linked Molecular Wedges………………………………………………….64

Chapter 6 Towards supramolecular columns via self-assembly of halogen-bonded charge
transfer complexes…………………………………………………………...……………….96

Appendix A Synthesis of a spacer containing wedge-shaped monondendron functionalized
with L-alanine…………………………………………………………………………….…121

Appendix B Towards dendronized poly((meth)acrylate)s forming columnar mesophases
stabilized via H-bonds……………………………………………….....................................136

Appendix C Ultrathin film of poly(acrylic acid-co-allylacrylate) as protective layer for
Titanium oxide decorated Glass.…………………………………………………………….151




6

Summary


This doctoral thesis deals mainly with the elaboration of new synthetic routes and self-
assembly studies of monodendrons with wedge-shaped molecular architecture.
The synthesis, thermal behaviour, liquid-crystalline properties and the self-assembly in
bulk and thin films of a series of wedge-shaped monodendrons with various length of the
peripheral alkyl chains (different number of carbon atoms, i.e., C6, C12 and C16)
functionalized with L-alanine at the focal point was studied. A combined differential scanning
calorimetry (DSC) and variable-temperature optical polarizing microscopy (TOPM) analysis
revealed that the monodendron with C6 is a crystalline compound with a melting point of
131.2 °C. Grazing-Incidence Wide-Angle X-ray Scattering GIWAXS studies of N-(3,4,5-
tris(hexyloxy))-benzoyl L-alanine in spin-coated films indicate that a crystalline material with
molecules packed in an orthorhombic crystal system with lattice parameters: a = 39.1Å, b =
16.4 Å, c = 9.7 Å, = = = 90° is formed. The unit cell contains eight monodendrons
organized in four dimers connected by hydrogen bonds with the peripheral hexyl chains
oriented normal to the substrate. The N-(3,4,5-tris(dodecyloxy))-benzoyl L-alanine displays
complex thermal behaviour displaying highly ordered liquid-crystalline phase. At
temperatures below 53 °C the molecules self-assemble into “smectic-like” phase
characterized by an interlayer spacing of 43.0Å, but in the temperature range between
approximately 53 and 76 °C the layer-like phase transforms into a more ordered hexagonal
columnar phase with the lattice parameter of 43.6 Å. The molecules self-assemble in
hydrogen-bonded hexamers organized on a hexagonal 2D lattice. In thin films, the columnar
axes are parallel to the substrate plane. At room temperature GIWAXS pattern of N-(3,4,5-
tris(hexadecyloxy))-benzoyl L-alanine indicate the formation of a columnar rectangular
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agbphase with the columns being parallel to the substrate (lattice parameters: a = 50.0 Å, b = 71.1
Å). At 50 °C the rectangular columnar structure transforms to a monoclinic phase (parameters
a = 43.0 Å; b = 16.8 Å; = 82.3°). The SFM analysis of monodendrons on HOPG showed
that the monodendron with C6 self-assemble into supramolecular helical columns with a
helical pitch of 13.2 nm, while the monodendron with C12 and C16 self-assemble into 2D
columnar structures.
A new low-symmetrical monodendritic molecule functionalized with a carboxylic acid
group at the focal point, 3,4-bis(dodecyloxy)-5-(3,4,5-tris(dodecyloxy)benzyloxy)benzoic
acid, was synthesized in high yield via a simple non-protecting group mediated route starting
from gallic acid ethyl ester. The combined DSC and TOPM analysis revealed a monotropic
liquid-crystalline phase on cooling between 38 °C and 14 °C. It was found that the extruded
fibers of the low-symmetry monodendron exhibits a stable rectangular columnar crystalline
phase and a monotropic smectic liquid-crystalline phase formed upon cooling from the
isotropic melt. In the crystalline structure the columns are formed due to specific arrangement
of crystalline and amorphous domains of alkyl chains. The 100 nm thick film reveals a
hexagonal columnar phase with the columns oriented parallel to the substrate.
The synthetic routes of three new monodendrons with pyridyl- and N,N-
dimethylpropyl- groups at the focal point, i.e., 3,4,5-tris(dodecyloxy)-N-(pyridin-4-
yl)benzamide, 3-(dimethylamino)propyl 3,4,5-tris(octadecyloxy)benzoate,
3-(dimethylamino)propyl 4-(3,4,5-tris(dodecyloxy)benzyloxy)benzoate as electron donor
components for halogen-bonded charge transfer complexes were elaborated. Synthesized
monodendrons were complexed with commercially available perfluorinated alkyl- and
aromatic iodides yielding highly crystalline complexes that do not exhibit any thermotropic
liquid-crystalline phases.
Chemo-(enzymatic) synthesis of two new macromonomers containing an amide bond
prone to form H-bonds, 3-(3,4,5-tris(dodecyloxy)benzamido)propylmethacrylate and 3-(3,4,5-
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gtris(dodecyloxy)benzamido)propylacrylate was elaborated starting from commercially
available gallic acid ethyl ester. Subjecting the monodendritic methacrylate to AIBN initiated
free-radical polymerization in toluene lead to a high-molecular weight polymer (M = w
4.900.000, M /M = 39.2) as well as unconverted macromonomer. w n
A synthetic route to new wedge-shaped monondendrons - N-(4-(3,4,5-
tris(dodecyloxy)benzyloxy))-benzoyl L-alanine methyl ester- and - N-(4-(3,4,5-
tris(dodecyloxy)benzyloxy))-benzoyl L-alanine was elaborated. The DSC analysis suggests
complex thermal behaviour of the prepared monodendrons characterized by several first-order
transitions.
Well-defined poly(acrylic acid-co-allyl acrylate) statistical copolymer