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Fabrication of tailor-made 2D crystalline and freestanding supramolecular- and metal-organic networks : use of interfacial assembly of amphiphilic calix[4]arenes

Moradi, Mina. Fabrication of tailor-made 2D crystalline and freestanding supramolecular- and metal-organic networks : use of interfacial assembly of amphiphilic calix[4]arenes. 2018, Doctoral Thesis, University of Basel, Faculty of Science.

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Official URL: http://edoc.unibas.ch/diss/DissB_13253

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Abstract

This thesis reports new strategies for the fabrication of two-dimensional (2D) free-standing
and crystalline tailor-made organic networks via bottom-up assembly of calix[4]arene organic
building blocks. Three major areas of work were conducted in this project:
1- Formation of novel 2D metal-organic coordination networks (MOCNs) of calix[4]arene
amphiphiles, i.e. a 2D MOCN of C3-p-carboxy-calixarene.
2- Fabrication of the first reported free-standing and crystalline linker-free 2D supramolecular
organic network (SON) through dipole-dipole interactions between C3-p-me-cyano-calixarene
building units.
3- In-situ synthesis of a bilayered MOCN of C3-p-me-carboxy-calixarene synthons with control
over the degree of bilayer formation.
The physical and chemical properties of 2D atomically ordered organic and inorganic
architectures, including strong in-plane and weak out-of-plane bonding, are unique and
distinct to those of the corresponding 3D structures. Thus, 2D materials have both
fundamental and applied importance to various applications ranging from superconductors to catalysis.1 Rational design and synthesis of 2D hybrid frameworks that enables control over
the resulting structures and functionalities can be achieved by applying the concepts of supramolecular and reticular chemistry.2 Numerous 2D supramolecular organic networks
have been produced by taking advantage of non-covalent interactions between organic
building units. In addition to supramolecular interactions, coordination bonds have also been
employed to link organic building blocks and single metal/metal complex nodes to synthesize 2D architectures, namely 2D MOCNs.3 A wide range of possible organic and inorganic building
blocks that possess coordination centers and electron donator/acceptor properties and
containing various selective functional groups and catalytic centers have been used to fabricate 2D architectures with desirable structures, properties and functions.3
Several bottom-up techniques for the fabrication of 2D materials have been reported,
including wet chemistry synthesis such as direct crystal growth from solvothermal solution,
chemical vapor deposition, surfactant-directed synthesis and interfacial self-assembly reactions.2 In bottom-up fabrication methods, the interfaces - where the reaction happens -
plays a pivotal role in the nucleation and growth of 2D materials. Interfacial self-assembly is d
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riven by reduction of the interfacial energy between the media.4 Assembly of nanomaterials
at interfaces with various geometries (e.g. nanosheets) has led the development of advanced
applications in many sectors such as polymer-based photovoltaic devices, magnetic data
storage media, polymer composites, oil and mineral refining, coatings, detergents and pharmaceuticals.5
In spite of the great progress in the field of 2D organic networks, there is a lack of practical
and versatile strategies to design, fabricate and characterize free-standing and crystalline 2D
nano-architectures. The research work described in this thesis led to development of a new
approach to produce free-standing and crystalline 2D organic networks of calix[4]arene
amphiphilic macrocycles. This work demonstrates 2D organic networks with specific desirable
properties and functions can be fabricated by tailoring the structure of the amphiphilic
calix[4]arene backbone. Indeed, this technique provides precise control over the organization
of the molecular building blocks down to the atomic level, i.e. enables molecular design.
The first chapter of this thesis reports the first example of a 2D MOCN of calix[4]arene organic
building blocks with tunable crystallinity. We show that carefully functionalized calix[4]arene
macrocycles containing carboxy functional groups at the upper rim and propyl chains at the lower rim form a free-standing and crystalline MOCN upon coordination with Cu2+ ions at the
air-liquid interface.
The second chapter provides the first report of linker-free 2D SON that is stabilized via
synergistic interactions of the dipole-dipole forces between calix[4]arene derivative building
blocks. A functionalized calix[4]arene synthon bearing methyl cyano functional groups at the
upper rim and propyl chains at the lower rim was designed. This amphiphilic calix[4]arene self
assembles and forms a crystalline 2D SON at the air-water interface. The crystalline layer can
be transferred from the interface onto a solid substrate, while maintaining the homogeneity
and crystallinity of the layer. Furthermore, free-standing layers of the 2D SON exhibit high
stability and can span perforated substrates with pores as large as 3 × 3 µm. Electron
diffraction analysis confirmed the crystallinity of the free-standing 2D SON.
The in-situ formation of a bilayered MOCN, at the air-liquid interface, from a functionalized
calix[4]arene carrying methyl carboxy groups at the upper rim and propyl chains at the lower
rim is reported in the third chapter. Calix[4]arene derivatives are shown to form monolayers
or bilayers upon changing the transition metal ion in the subphase. In the presence of Cu2+
ions, a free-standing and crystalline MOCN bilayer forms, in which the degree of bilayer
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formation can be kinetically controlled. Substituting the Cu2+ ions with Ni2+ ions results in
formation of a crystalline and free-standing monolayer of MOCN. These observations
confirmed that the conformational freedom and flexibility of the modified calix[4]arene
building components enable adoption of different coordination geometries in the MOCN,
depending on the transition metal ion employed.
These highly stable 2D calix[4]arene-based organic networks can potentially be applied as a
new generation of sample supports for transmission electron microscopy imaging and X-ray
analysis of single biomolecules/assemblies and single-magnetic nanoparticles. Indeed, some
examples of biomolecule, assembly and nanoparticle deposition experiments on free-standing
coordination networks of calix[4]arene amphiphiles are presented in this thesis. Further work
is currently underway to extend this research and define advanced methods to enhance the
structural analysis of single biomolecules and the magnetic properties of nanoparticles
deposited on free-standing monolayers of calixarenes and related compounds.
Keywords: supramolecular chemistry, reticular chemistry, 2D metal-organic coordination
network, 2D supramolecular-organic network, self-assembly, Langmuir-Blodgett technique,
calix[4]arene amphiphile, amphiphilic bilayers.
Advisors:Jung, Thomas and Shahgaldian, Patrick and Therrien, Bruno
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Growth & Development > Biochemistry (Spiess)
Item Type:Thesis
Thesis Subtype:Doctoral Thesis
Thesis no:13253
Thesis status:Complete
Bibsysno:Link to catalogue
Number of Pages:1 Online-Ressource (viii, 129, 2 Seiten)
Language:English
Identification Number:
Last Modified:05 Sep 2019 09:29
Deposited On:05 Sep 2019 09:27

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