Ami Thesis 1 inch 011310

344 Pages·2010·3.31 MB·English

FUNCTIONALIZED ORGANOBORON POLYMERS AND
SUPRAMOLECULAR STRUCTURES OF
PENTAFLUOROPHENYLCOPPER
By Ami P. Doshi
A dissertation submitted to the
Graduate School-Newark
Rutgers, The State University of New Jersey
in partial fulfillment of the requirements
for the degree of
Doctor of Philosophy
Graduate Program in Chemistry
Written under the direction of
Professor Frieder Jäkle
and approved by

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Newark, New Jersey
January, 2010
ABSTRACT OF THE THESIS

FUNCTIONALIZED ORGANOBORON POLYMERS AND
SUPRAMOLECULAR STRUCTURES OF
PENTAFLUOROPHENYLCOPPER

By Ami Doshi
Thesis Director: Professor Frieder Jäkle

This thesis is divided into four different parts. The first three chapters discuss the
development of synthetic routes to new boron containing polymers for their potential use
as supported borane reagents (Ch. 1.) and photoluminescent materials (Ch. 2. and Ch. 3.).
The last chapter (Ch. 4.) discusses the formation of supramolecular structures of
pentafluorophenylcopper upon complexation with pyridine nucleophiles and electron rich
aromatic π-systems. The individual research projects are briefly summarized in the
following.
Ch. 1. The functionalization of synthetic polymers with organoborane moieties has been
extensively studied for applications as supported catalysts, sensors, stimuli responsive
polymers, flame retardants, preceramic materials, and as intermediates for the preparation
of other functional organic polymers. A polystyrene derivative in which the para-
positions of the phenyl rings are selectively functionalized with BH moieties (PS-BH )
2 2
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has been prepared from poly(4-trimethylsilyl styrene). The polymer was successfully
isolated in the form of its polymeric acid-base complexes PS-BH •D (D = tBuPy,
2
PPh Me). The selective and nearly quantitative placement of the BH functionalities was
2 2
confirmed by multinuclear NMR spectroscopy and IR spectroscopy. Their thermal
properties were studied by differential scanning calorimetry and thermogravimetric
analysis.
Ch. 2. Boron containing water soluble polymers could find a variety of applications as
polyelectrolytes, for anion recognition in aqueous media and in various biological fields.
We have previously shown that polystyrene based side chain functionalized triarylborane
polymers can be employed as sensors for the recognition of cyanide and fluoride in
organic media. Here we have persued the synthesis of polystyrene that bears Lewis acidic
boron centers and dimethylamino-functionalized mesityl groups in the side chain.
Attachment of these mesityl groups to the boron center has been realized by the use of
boron-silicon exchange, followed by the replacement of the bromine on boron by suitable
Grignard reagents. The polymers and model compounds show interesting photophysical
properties and have the potential to be applied for anion sensing in aqueous media.
Ch. 3. Main chain organoboron conjugated polymers have been established as an
important class of materials due to their unusual optoelectronic properties. This behavior
arises as a result of overlap between the empty p-orbital on boron and the conjugated π-
system. The hydroboration polymerization and in situ Grignard synthesis have been
employed for the preparation of such polymers. Here we have synthesized boron-
functionalized distyryl monomers, which can be polymerized via ADMET
polymerization. All monomers and ADMET products were characterized by multinuclear
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NMR spectroscopy. Moderate to high molecular weights in the range of 5,000-10,000
have been obtained. Photophysical data show that polymer emits in the blue-green region.
Ch. 4. Treatment of organocopper species with strongly coordinating ligands is known to
lead to break-down of the aggregated structures. One such example is the 1:1 complex of
pentafluorophenylcopper with pyridine. The monomeric pyridine adduct shows an
intriguing supramolecular structure governed by cuprophilic interactions. This complex
was also found to display strong blue luminescence in the solid state at room temperature.
To further examine the structural and photophysical properties of this new class of
complexes, the pentafluorophenylcopper tetramer was treated with different substituted
pyridine ligands. The coordination of these ligands to copper was confirmed by 1H, 19F,
13C NMR spectroscopy, x-ray crystallography and elemental analysis.
Treatment of pentafluorophenylcopper with π-bases such as bithiophene, naphthalene
anthracene or pyrene lead to novel luminescent supramolecular structures that feature the
intact organocopper aggregate as the building block. Formation of bis-adducts with two
equivalents of arenes was realized and the formation of sandwich-like structures of the
intact tetramer and the corresponding arene was observed via single crystal x-ray
analyses. Interestingly, the 1:1 complexes form extended binary stacks in the solid state,
where the intact tetramer alternates with the arene.

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Dedicated to my Late Father
Mr. Pravinchandra O. Doshi

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Acknowledgments

I wish to express my sincere thanks to my supervisor, advisor and mentor, Prof. Frieder
Jäkle, for his helpful support, guidance and encouragement throughout my Ph.D. study. I
would also like to thank him for always being helpful, understanding and patient through
any ups and downs, both on a personal as well as the professional front.
I would like to thank my committee members, Prof. Elena Galoppini, Prof. Philip
Huskey and Prof. Sergiu Gorun of NJIT at Newark, NJ, for spending their time reading
and correcting my thesis, and for their helpful advice and encouragement.
I would like to thank Prof. Ralf Peetz and his student Arijit Sengupta (CUNY-Staten
Island) for their collaboration, helpful discussions and all their help with synthesis and
characterization of the boron containing ADMET polymers. I would specially like to
thank Prof. Roger A. Lalancette for his help with solving and determination of structural
parameters. I would also like to thank Dr. Lazaros Kakalis for helping me with NMR
measurements. Thanks to Prof. Arnold L. Rheingold, of University of California, San
Diego, and Dr. Krishnan Venkatasubbaiah of Rutgers University, Newark, for performing
x-ray crystal structure determinations. I also thank all my professors who taught me
throughout my graduate program. In addition, I would like to thank my colleagues and
former group members for their help and support.
Finally, I am very grateful to my family and friends for giving me continuous
support and encouragement. I would like to dedicate this thesis to my late father Mr.
Pravinchandra O. Doshi, my mother Mrs. Sudha P. Doshi and my dearest husband Kshitij
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Parab; whose support, patience, understanding and unconditional love gave me strength
and enthusiasm to pursue my dreams and aspirations.

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Disclaimer

The x-ray crystal determination for 4-MePy-CuC F (18), 4-ClPy-CuC F (20), (Bt) -
6 5 6 5 2
CuC F (28), (Pyr) -CuC F (33) on pages 198, 200, 216, and 227 was carried out by
6 5 2 6 5
Prof. Arnold L. Rheingold at University of California, San Diego.
The x-ray crystal determination for 2-MePy-CuC F (19), 2-ClPy-CuC F (21), and
6 5 6 5
(Naph)-CuC F (29) on pages 200, 201, and 218 was carried out by Dr. Krishnan
6 5
Venkatasubbaiah at Rutgers University, Newark, NJ.
The ADMET polymerization of monomer (29), on page 159 was carried out by Arijit
Sengupta at College of Staten Island, The City University of New York.

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Table of Contents

Abstract of Thesis ii
Dedication v
Acknowledgements vi
Disclaimer viii
Table of Contents ix
List of Figures xvii
List of Schemes xxi
List of Tables xxiii
List of Charts xxiv
Chapter 1. General Introduction. 1
1.1 Organoboron Polymers. 1
1.2 Synthesis of Boron Containing Polymers. 2
1.2.1 Direct Polymerization of Boron Monomers. 2
1.2.2 Polymer Modification Reactions. 8
1.2.2.1 Modification of Polyolefins. 8
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1.2.2.2 From Mercuriated Polystyrene. 9
1.2.2.3 Side-chain Functionalized Organoboron 10
Polymers via Si-B Exchange Reactions.
1.3 Applications of Boron Containing Polymers. 11
1.3.1 Applications in Organic Synthesis and Catalysis. 12
1.3.2 Applications as Sensor Materials. 12
1.3.3 Other Applications. 15
1.4 References and Notes. 16
Chapter 1A. Boron Polymers as Supported Reagents. 22
1A.1 Polymers Supported Reagents. 22
1A.2 Synthesis of Supported Borane Reagents. 23
1A.3 Hydroboration Chemistry. 29
1A.4 Results and Discussion. 34
1A.4.1 Synthesis. 34
1A.4.2 Structural Characterization. 37
1A.4.2.1 Multinuclear NMR Spectroscopy. 37
1A.4.2.2 IR Spectroscopy. 39
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