Porphyrins with extended π-electronic networks are promising candidates for a wide range of applications from medicine to nanotechnology owing to their unique optical and electronic properties. This dissertation is focused on synthesis, characterization and application of β-functionalized π-extended porphyrins. This dissertation is comprised of seven chapters. Chapter 1 focuses on the importance and objective of this work. Chapter 2 gives brief introduction to porphyrins and π-extended porphyrins. In chapter 3, a class of β-functionalized linear push-pull zinc dibenzoporphyrins YH1-YH3 were designed, synthesized, and utilized as light harvesters for DSSCs. In chapter 4, in order to further enhance the photovoltaic performance of β-functionalized benzoporphyrin dyes based DSSCs, a new class of push-pull dibenzoporphyrins YH4-YH7 bearing the phenylethynyl bridge was designed, synthesized and utilized as light harvesters for DSSCs. In chapter 5, in order to solve the photodegradation problem associated with YH7, a new series of push-pull dibenzoporphyrins YH8-YH10 bearing different diarylamino push groups was designed and synthesized. This class of push-pull porphyrins shows improved photostability and enhanced DSSC performance. In chapter 6, a new pentacene-fused diporphyrin with high stability and solubility was prepared and characterized. Chapter 7 includes the summary of this dissertation and describes possible future work.

Membrane technology is one of the most promising technologies for addressing the global water crisis as well as in many other applications. One of the drawbacks of current ultra- and nanofiltration membranes is the relatively broad pore size distribution. Block copolymer membranes with ultrahigh permeability and very regular pore sizes have been recently demonstrated with pores being formed by the supramolecular assembly of core/shell micelles. Our study aimed at developing an innovative and economically efficient alternative method to fabricate isoporous membrane by self-assembly of magnetic nanoparticle with a polystyrene shell, mimicking the behavior of block copolymer micelle. Fe3O4 nanoparticles of ~13 nm diameter were prepared by co-precipitation as cores. The initiator for ATRP was covalently bonded onto the surface of magnetic nanoparticles with two strategies. Then the surface initiated ATRP of styrene was carried out to functionalize nanoparticles with polystyrene through a “grafting from” method. Finally, the nanocomposite membrane was cast from 50 wt % Fe3O4@PS brush polymer solution in DMF via non solvent phase inversion. Microscopies reveal an asymmetric membrane with a dense thin layer on top of a porous sponge-like layer. This novel class of asymmetric membrane, based on the pure assembly of functionalized nanoparticles was prepared for the first time. The nanoparticles are well distributed however with no preferential order yet in the as-cast film.I would like to thank my committee chair and advisor, Prof. Suzana Nunes, and other committee members, Prof. Klaus-Viktor Peinemann and Prof. Gary Amy, for their guidance and support throughout the course of this research. My appreciation also goes to my colleagues in our group for useful discussions and suggestions. I also want to extend my gratitude to the staff from the KAUST Core Lab for Advanced Nanofabrication, Imaging and Characterization, especially Dr. Ali Reza Behzad, Dr. Rachid Sougrat, and Dr. Long Chen, for their assistance for various microscopy measurements. Finally, my heartfelt gratitude is extended to my parents and all my friends. I cannot finish this thesis without their encouragement and support.

No description available.

Molecular beam scattering experiments are used to investigate the extent of thermal accommodation of Ne, CD4, ND3, and D2O in collisions with long chain CH3, NH2, and OH terminated self-assembled monolayers (SAMs) on gold. Surface rigidity, internal degrees of freedom of the impinging gas, and potential energy surface well depths have been explored as a way to predict the outcome of a gas-surface collision. Ne is used to assess the mechanical rigidity of the SAMs. The order of rigidity is CH3 < NH2 ~ OH. The NH2 and OH terminated SAMs are more rigid due to the intermolecular hydrogen bonding structure at the gas-surface interface. Despite the hydrogen bonding nature of the NH2 and OH terminated SAMs CD4, ND3, and D2O are extensively thermally accommodated on the surfaces, therefore surface rigidity is no solely responsible for energy transfer dynamics. It was found that the number of degrees of freedom do not predict how extensively a gas will thermally accommodate on a surface capable of hydrogen bonding. A qualitative correlation between increasing potential energy well depths and the extent of thermal accommodation has been established as a result of these scattering experiments. / Master of Science

III-nitride mainly GaN semiconductors are the most important materials for a wide range of applications, in particular high-power devices, due to the tunable direct bandgap, their chemical, and thermal stability. However, their growth on suitable substrates is still problematic, and low UV GaN efficiency hinders the efforts aimed at improving the performance of emitting devices. This dissertation presents novel growth and device fabrication methods capable of overcoming these issues using different novel strategies. The work reported in this dissertation comprises five parts. The first two parts demonstrate a new low-cost pulsed laser deposition (PLD)-based strategy for large-scale applications. This was developed to grow high-quality dislocation-free GaN NWs epitaxially on any bulk, flexible, or two-dimensional (2D) substrates without a catalyst, irrespective of the lattice mismatch or type of the substrate. As part of the work reported here, Si, p-GaN, Ga2O3, sapphire, graphene, MXene, and transition-metal dichalcogenide (TMD) substrates were utilized. Also, the adopted growth mechanisms are discussed, along with the advanced structural and optical characterizations. Advanced structural and optical characterizations further confirm the growth mechanism and demonstrate the superior optical and structural quality of GaN NWs. In the third part, a novel multiple quantum wells (MQWs)-based structure grown on the NWs is described, indicating that these NWs can be used as a template to grow III-nitride-based devices. In the fourth part of the work, the significance of these GaN NWs is further demonstrated by reporting on the fabrication of a high-performance self-powered broadband photodetector incorporating these NWs hybridized by two perovskite types: organic/inorganic as well as all-inorganic perovskites (CH3NH3PbI3 and CsPbBr3), revealing two different self-powered photodetector characteristics with high photo-responsivity at 0V. In the last part of this work, the focus is given to a new environmentally friendly strategy to enhance the device UV emission efficiency by functionalizing GaN NWs with solution-processed p-MnO quantum dots (QDs) characterized by much wider bandgap energy than that of GaN. The energy transfer mechanism from QDs to NWs is also discussed using different structural and optical characterizations. This novel strategy is based on drop-casting QDs on NWs, which is simple, cost-effective, and applicable for large-scale applications.

Metal ion contamination in surface and ground water is a major threat as it has a direct implication on the health of terrestrial and aquatic flora and fauna. Lead (Pb2+), mercury (Hg2+), cadmium (Cd2+), nickel (Ni2+), copper (Cu2+) and cobalt (Co2+) are few of these metal ions which are classified under the high risk category. Of these, lead and mercury are of greater concern, as even nanomolar concentrations can be lethal, as they can be bio-accumulated and result in physiological as well as neurological disorders. In Asian countries like India and China, heavy metal pollution is more prevalent, as a consequence of poor governmental policies or ineffective or inadequate measures to combat this problem. In recent times, the monitoring and assessment of water pollution is a critical area of study, as it has a direct implication for its prevention and control. The major techniques used for metal ion detection are atomic absorption spectroscopy (AAS), X-ray fluorescence, ion chromatography, neutron activation, etc. Alternatively, the electrochemical, optical and electrical methods provide a platform for the fabrication of portable devices, which can facilitate the on-site analysis of samples in a rapid and cost-effective manner. This has led to a new field of research called chemical sensors or chemo sensory devices. The main aim of this study is to develop various chemosensory materials and test their response towards metal ion sensing. In this study, electroactive polymers have been synthesized for various sensor applications. The focus has been to design synthesize and test various functionalized electroactive polymers (FEAP) for the development of electrochemical, optical and chemoresistive sensors. Electroactive polymers like polyaniline, polypyrrole, polypyrrole grafted to exfoliated graphite oxide and dipyrromethene conjugated with p-(phenylene vinylene) have been synthesized and evaluated after functionalizing with metal coordinating ligands. These metal coordinating ligands were selected, in order to enhance their metal uptake capacity. Various metal ligands like imidazole, tertiary amine group, iminodiacetic acid, and dipyrromethene incorporated either in the polymer backbone or as a part of the backbone have been chosen for the metal binding. These functionalized electroactive polymers (FEAP) served as active material for metal ion sensing. The present investigation is subdivided into three sections. The first part includes design and chemical synthesis of the functionalized polymers by a series of organic reactions. The synthesis has been followed up by characterization using spectroscopic methods including NMR, FTIR, GCMS and Mass spectrometry. In the second part of the investigation, the synthesized polymer has been characterized for the changes in electronic, electric and optical properties after interaction with the selected metal ions. For this, the FEAP is allowed to interact with various metal ions and the changes in the relevant properties have been measured. This includes the study of changes in the conductivity, electronic properties like absorption or emission of the polymer, changes in the redox properties, etc. The third phase of investigation deals with the fabrication of the devices using the active FEAP. The sensor devices comprised of either films, or electrode modified with FEAP or solution of the FEAP, in combination with an appropriate technique has been used for the sensing. The major objectives are enumerated below 1. Functionalzation of polyaniline with imidazole functional group to get imidazole functionalized polyaniline (IMPANI) and study of the electronic, electrical and optical properties of the same. 2. Preparation of films of IMPANI and study of the change in conductivity of the film upon interaction with various metal ions, namely Cu2+, Co2+ and Ni2+ in their chloride form. 3. Synthesis of amine functionalized aniline monomer and chemical graft polymerization onto exfoliated graphite oxide as a substrate to synthesise the amine funtionalised polyaniline grafted to exfoliated graphite oxide (EGAMPANI). Modification of the carbon paste electrode (CPE) with EGAMPANI and study of the electrode characteristic. 4. Study of the electrode properties of EGAMPANI modified carbon paste electrode. 5. Evaluation of the EGAMPANI modified carbon paste electrode as a multi-elemental voltammetric sensor for Pb2+, Hg2+ and Cd2+ in aqueous system. 6. Functionalization of polypyrrole with iminodiacetic acid and characterization of the polymer to synthesis iminodiacetic acid functionalized polypyrrole (IDA-PPy). 7. Modification of the CPE with IDA-PPy by drop casting method and evaluation of the Pb2+ sensing properties. 8. Study of the effect of other metal ions say Hg2+, Co2+, Ni2+, Zn2+, Cu2+ and Cd2+ on the anodic stripping current of Pb2+ using EGAMPANI modified CPE. 9. Synthesis of dipyrromethene-p-(phenylene vinylene) conjugated polymer for heavy metal ion sensing. 10. Study of the changes in the optical absorption and emission properties of the polymer in THF and evaluation of the change in these optical properties upon interaction with the metal ions as analyte. The salient findings of the research work are highlighted as follows, In the first synthesis, aniline has been functionalized with imidazole group and this monomer has been chemical oxidatively polymerized to obtain imidazole functionalized polyaniline (IMPANI). The synthesized polymer possesses a nano-spherical structure, as confirmed from the morphological characterisation using scanning electron microscopy. The IMPANI has been interacted with a representative metal ion, copper (II) chloride, and the copper complexed polymer (Cu-IMPANI) has been subjected to various studies. The coordination of copper with IMPANI results in an increase of molecular weight of the polymer as a result of aggregation, as observed from dynamic light scattering measurements. Apart from this, a significant finding is the decrease of the pH of the system after copper ion coordination attesting to the generation of a secondary hydrochloride ion during the coordination of the copper to the imidazole side chain. This is further confirmed by an increase in conductivity of the Cu-IMPANI compared to IMPANI, measured using the four-probe technique. The increase of conductivity due to copper coordination is one order of magnitude higher. The films which have been prepared from IMPANI and Cu-IMPANI exhibit different morphology. The Cu-IMPANI film prepared by prior co-ordination of Cu ion with IMPANI powder shows a flaky structure, which is not preferable for the conductivity measurements, as a consequence of discontinuity in the medium. To overcome this problem, IMPANI films were initially prepared and then interacted with copper ions for a desired duration, before measurement of the conductivity. This latter procedure enabled the preparation of smooth films for the development of chemoresistive sensors. In continuation of the initial study highlighted above, IMPANI films of thickness 0.02 ± 0.001 mm have been prepared using IMPANI and PANI in DMPU in the ratio of 7:3 by mass. After exposure of the films with respective metal chlorides, such as Ni2+, Co2+ and Cu2+, a change in conductivity is observed in the concentration range of 10-2 to 1 M of metal chlorides. The sensor response may be arranged in the sequence: Ni2+ > Cu2+ > Co2+ at 1M concentration. On the contrary, films prepared from PANI-EB under identical conditions do not exhibit any appreciable change in conductivity. The optimum exposure time is determined to be 10 min for a maximum change in conductivity, after exposure to the chosen metal ions. In the second system taken up for investigation, a tertiary amine containing polyaniline (AMPANI) has been grafted to exfoliated graphite oxide. The amine containing polyaniline grafted to exfoliated graphite oxide (EGAMPANI) has been characterised for structural, morphological and elemental composition. The grafting percentage has been determined to be 7 % by weight of AMPANI on the EGO surface. The synthesized EGAMPANI (5 weight %) has been used to modify carbon paste electrode (CPE) for electrochemical sensor studies. Based on the differential pulse anodic stripping voltammetric studies, the electrochemical response may be arranged in the following sequence: Pb 2+>Cd 2+>Hg 2+ The minimum detection levels obtained are 5×10-6, 5×10-7, and 1.0×10-7 M for Hg2+, Cd2+ and Pb2+ ions respectively. In the next study, an iminodiacetic acid functionalized polypyrrole (IDA-PPy) has been synthesized and characterised for its elemental and structural properties. This has been further used to modify the CPE by drop casting method and used for the specific detection of Pb2+ in acetate buffer. Various parameters governing the electrode performance such as concentration of depositing solution, pH of depositing solution, deposition potential, deposition time, and scan rate, have been optimized to achieve maximum performance and found to be 20 μl, 4.5, -1.3 V, 11 min, 8 mV s-1 respectively for the chosen parameters. Additionally, the influence of other heavy metal ions on the lead response has been studied and it is observed that Co, Cu and Cd ions are found to be interfering. Further, the response of Cd, Co, Cu, Hg, Ni and Zn on IDA-PPy functionalized electrode has been evaluated. The selectivity of IDA-PPy modified electrode for Pb2+ is observed in the concentration range of 1 × 10-7 M and below. The IDA-PPy modified CPE shows a linear correlation for Pb2+ concentration in the range from 1×10-6 to 5×10-9 M and with a lowest limit of detection (LLOD) of 9.6×10-9 M concentration. The efficacy of the electrode for lead sensing has also been evaluated with an industrial effluent sample obtained from a lead battery manufacturing unit. The fourth synthesis pertained to the development of an optical sensor for Fe2+, and Co2+ ions. For this, dipyrromethene as a metal coordinating ligand in conjugation with p-phenylenevinylene has been synthesized and tested for its structural as well as optical properties. It is observed that the polymer shows three absorptions, namely at 294 nm, 357 nm and a major absorption observed as a broad band ranging from 484 to 670 nm. The emission spectrum of the polymer excited at 357 nm shows a characteristic blue emission with a maximum intensity centered at 425 nm. The emission quenching in the presence of various metal ions have been tested and are found to be quenched in presence of Fe2+ and Co2+ ions. All the other metal ions tested namely, Cr3+, Cu2+, and Zn2+ are not found to exhibit any change in the emission spectra below the concentration of 1 × 10-4 M. The linear correlation of the emission intensity with the concentration of the Co2+ and Fe2+ ions has been determined using Stern-Volmer plot. For Co2+ the Stern-Volmer regime is observed from 1×10-4 to 9×10-4 M concentration and the quenching constant Ksv is determined to be 8.67 ×103 M-1. For Fe2+, the linearity is found to be in the regime of 1×10-5 to 9×10-5 M and the quenching constant Ksv is determined to be 7.90 × 103 M-1. In conclusion, different electroactive polymers functionalized with metal coordinating ligands have been synthesized, characterised and evaluated for metal sensing applications. Techniques like electrochemical, optical and conductivity have been used to characterise the response of these FEAP towards metal sensing. It is can be concluded that the electrochemical sensors are more reliable for sensing especially at very low concentrations of metal ions such as Pb, Cd and other techniques like optical and conductimetric are good for detecting metal ions namely Fe, Co, Ni, Cu. The selectivity towards the metal ions is a function of the metal chelating ligand and the extent of sensitivity is dependent upon the technique employed.

Doctor of Philosophy / Department of Chemistry / Eric A. Maatta / Polyoxometalates are self-assembled metal-oxygen anionic clusters formed primarily by Mo, W and the Group V transition metals. Their structural, chemical and physical diversity have attracted much attention from fields such as catalysis, imaging, magnetic materials, medicine and photochromism. While many of these inorganic systems are easy to prepare, their conversion to hybrid inorganic-organic materials through functionalization is an ongoing challenge. Two approaches used for functionalization involve the insertion of metal-nitrido fragments into a lacunary polyoxometalate or the direct replacement of the terminal oxo ligands with the isoelectronic organoimido [NR][superscript]2-, hydrazido [NNR[subscript]2][superscript]2-, nitrosonium [NO][superscript]+ and diazenido [NNR][superscript]+ ligands. The later process has been proven successful with a variety of different nitrogenous ligands. One of our group's goals has been to synthesize a functionalized hexamolybdate species capable of metal coordination, with the ultimate goal of forming self-assembled networks. However, previous results have been unsuccessful due to the electron withdrawing effect of the cluster which is transmitted to the metal binding site. In order to overcome this effect, several new organoimido delivery reagents (phosphineimines, isocyanates and arylamines) containing electron donating substituents have been synthesized and characterized. Attempts to attach these species to hexamolybdate are described. The synthesis and characterization of biarylimido ligands bearing remote σ-donor functionalities and their incorporation into the hexamolybdate cluster will be described. A new and exciting avenue of polyoxometalate chemistry will be demonstrated through the successful metal coordination of the biarylimido functionalized hexamolybdate to a ruthenium(II) metalloporphyrin. This also brings the hexamolybdate polyoxometalate one step closer to being capable of forming the supramolecular architectures mentioned earlier. A chromium(V) nitrido polyoxometalate has been synthesized and characterized from a lacunary Keggin precursor, in collaboration with our colleagues in Paris. The ability of this complex as a nitrogen transfer reagent will be explored. An alternative synthetic route to the osmium-nitrido-Dawson species, [(OsN)P[subscript]2W[subscript]17O[subscript]61][superscript]4- will also be described. These nitrido species could be an entry point to other derivatives through reactions with various nucleophiles and electrophiles.

<p><p>There are different kinds of recognition molecules that specifically can detect and bind target molecules. Antibodies, with their two light and two heavy chains can detect and bind any kind of antigens. Molecular imprinting is a technology to prepare specific polymers that selectively bind target molecules. The technology has received wide attention in recent years because it provides a viable method for creating a polymer that is complementary in shape and binding sites to a template. The synthesized polymer is called a molecularly imprinted polymer (MIP) or a plastibody. Molecular imprinting shows promise in diverse areas as chromatography, antibody mimics, solid phase extraction and more. An alternative to molecular imprinting and other types of recognition has recently been postulated where DNA polymers based on functionalized polynucleotides build up a polymer network that are able to specifically recognize a target. This approach is characterized by binding of oligonucleotides carrying functional organic groups, to the target molecule followed by connecting the functionalized oligonucleotides forming a DNA polymer that specifically recognizes the target. The polymer is called a DNAbody. Thus, a DNAbody is a polymer structure based on DNA conjugated with functional organic groups which specifically can detect and bind to a template. The DNA-bodies can be copied and produced in larger amounts by PCR. This study showed that at least one functional oligonucleotide was able to interact with the target antibody. It was also seen that some interaction occurred between the DNA and protein. The results also indicated that it is possible to perfom DNA polymerase reactions in presence of an antibody.</p></p>

Conducting polymers have emerged as a promising material for optoelectronics and chemical sensing application. Polyaniline (PANI) is a conductive polymer which can be easily functionalized to be specific for various biomolecules and has ideal sensor characteristics. The protonation and deprotonation of the polyaniline’s backbone by derivatization can result in color and conductive change responses. This makes it ideal for the construction of a real time, naked eye sensor. Derivatized polyaniline has previously been reported as a colorimetric sensor in solution. We plan to create a more practical sensor by synthesizing hydroxyl functionalized polyaniline thin films. In this study, we designed a process to functionalize polyaniline and deposit it as a thin film on quartz or silicon substrate via a dip coating process. To demonstrate the use of derivatized PANI in biosensing applications, derivatized and underivatized PANI thin films were treated with solutions of L-aspartic (Asp) acid at concentrations ranging from 10-8 mM to 103 mM and monitored utilizing UV-Vis spectroscopy. We found that the derivatized thin films change from deep blue to green color upon addition of Asp solution and showed a decrease in the characteristic quinoid ring peak at 600nm and the appearance of a new polaron peak at 425nm. The underivatized PANI films showed no colorimetric response indicating the hydroxyl functionalized PANI films are a more ideal material for a biosensing and naked eye detection. The polyaniline derivative was characterized using FT-IR spectroscopy, 1H NMR spectroscopy, UV-VIS spectroscopy, and Scanning Electron Microscopy. Additionally, conductivity studies were utilized to explore the material’s effectiveness as an electronic sensor using a 4-point probe to measure resistance.

Desenvolveu-se neste trabalho um procedimento para incorporação de nanotubos de carbono (NTC) em uma resina fenol / epóxi a ser utilizado como matriz de um compósito de fibra de carbono. Realizando para tal, a oxidação dos NTC com o uso de micro-ondas e sua funcionalização com 3-amino-propil-tri-etoxi-silano, usado com agente de acoplamento entre a resina e o NTC. Após o processamento, como resultado da adição dos NTC na resina, obteve-se um aumento na sua temperatura de transição vítrea e uma melhora no limite de resistência à flexão e impacto. No material compósito fibra de carbono, obtido por laminação manual, onde a resina fenol / epóxi mais NTC foi usada como matriz, obteve-se o aumento do limite de resistência à tração e ao impacto, confirmado por uma análise de variância com 95% de confiança, mostrando a eficácia no tratamento dos NTC. / This work has developed a procedure for incorporating carbon nanotubes (CNT) on a phenol / epoxy matrix to be used as a carbon fiber composite. Performing for such oxidation of the NTC with the use of microwaves and their functionalization with 3- aminopropyl-triethoxysilane, a coupling agent used between the resin and CNT. After processing, as a result of the addition of CNT, the resin obtained an increase in the glass transition temperature and an improvement in flexural strength and impact resistence. In the carbon fiber composite, hand lay-up prepared, where the phenol / epoxy and CNT was used as a matrix, we obtained the increase in the limit of tensile strength and impact resistance, confirmed by an analysis of variance with 95% confidence, showing efficacy in the treatment of CNT.