The main thrust of this thesis is the development of facile synthetic routes for simple boryl anilines and study their structure-property correlations in both solid and solution states and to utilize this information to design functional materials with desired properties such as aggregation induced emission, mechanofluorochromism, and thiol sensors. This thesis contains eight chapters and the contents of each chapter are described below. Chapter 1 The first chapter is an introduction to the theme of the thesis and presents a general review on the present work with emphasis on photophysics of triarylboron based donor-acceptor systems and their applications in various fields. In addition, advances in boron chemistry in the new frontier areas such as aggregation induced emission and mechanochromism are discussed in brief. Chapter 2 The second chapter deals with the general experimental techniques and synthetic procedures utilized in this work. Chapter 3 This chapter describes the rational design and synthesis of triarylborane bearing Unsubstituted amines, namely borylanilines (3.1-3.5). Compounds 3.1-3.4have similar donor and acceptor centres but differ their molecular conformations and also differ in the relative positions of amine moiety (para and meta). Compounds 3.1-3.4 contain one amine group while 3.5 contains two amine moieties. These compounds exhibit fascinating electrostatic intermolecular interactions, N −H- - -π in the crystal structure of 3.1, 3.2 and 3.4 and N −H--N interactions in crystal structure of 3.5. The solution state optical properties of 3.1-3.5 are typical of donor-acceptor (D-A) systems. Interestingly, compounds 3.3 and 3.5 showed unprecedented mechanochromic luminescent properties. Upon grinding, compound 3.3 showed color changes from blue to cyan blue and 3.5 showed intriguing color changes from blue to green and these color changes were found to be reversible. Single crystal X-ray diffraction analysis of 3.5BP (blue emission color crystal) and 3.5GP (green emission color crystal) clearly show that the color changes are due to the difference in their solid state packing. Chapter 4 In chapter 4, the design and facile synthesis of boron based donor-acceptor (D-A) systems such as borylanilines 4.4-4.9 (D= -NH2 for 4.4-4.6 and -NMe2 for compounds 4.7-4.9) are reported. Compounds 4.4, 4.5 and 4.6 contain one, two or three -NH2 moiety(ies), respectively. Compounds 4.7, 4.8 and 4.9 contain one, two or three –NMe2 moiety(ies), respectively. A systematic investigation has been carried out to rationalize the effect of donor-acceptor ratio on the ICT process in borylanilines 4.4-4.9. The aryl spacer between donor amine and acceptor boron is kept the same in all the compounds to avoid the electronic effect of spacer on the ICT characteristics of these compounds. In the case of compounds 4.4-4.6, the increase in the number of donor -NH2 moieties does not affect their absorption profile, while in the case of compounds 4.7-4.9, the absorption spectra are shifted bathochromically with an increase in the number of donor-NMe2 moieties. Photoluminescence (PL) of 4.4-4.6 is significantly blue shifted with an increase in number of –NH2 moieties, while the PL of 4.7-4.9 was slightly blue shifted. The absorption and PL features of 4.4-4.6 are sensitive to the polarity of the solvent medium. In contrast, absorption profiles of 4.7-4.9 are not sensitive to the polarity of the solvent medium. The PL of these compounds is affected by the polarity of the solvent medium. Chapter 5 This chapter deals with triarylboron based fluorescent probes (5.1-5.4) for the selective detection of thiophenols over aliphatic thiols. The probes were constructed by conjugating luminescent borylanilinies with luminescent quencher 2,4-dinitrobenzene sulfonyl (DNBS) moiety. In compound 5.1 and 5.2 the DNBS moiety is positioned at the para position with respect to the triarylborane moiety, while in 5.3 and 5.4 the DNBS moiety(ies) is(are) at the meta position(s). Probes 5.1-5.4 showed selective turn-on fluorescence response towards thiophenol. The fluorescence “off-on” switching mechanism of 5.1-5.4 against thiophenols was fully elucidated by theoretical calculations. Probes 5.1-5.4 are also capable of detecting thiophenols in the intra cellular environments. Chapter 6 Design, facile synthesis and aggregation induced emission properties of a new series of novel triarylboron tethered N-aryl-1,8-naphthalimides (TAB-NPIs) 6.1-6.7 are described in this chapter. Systematic structural perturbation has been used for fine-tuning the optical and morphological properties of TAB- NPIs in both solid as well as in aggregated state. Compounds 6.1-6.7 are weekly luminescent in solutions. In contrast, all compounds (except compound 6.4) are strongly luminescent in the solid state and aggregated state in THF-H2O mixtures. The presence of sterically hindered boryl unit in 6.1-6.7 has endowed these molecules with unique AIE characteristics by preventing co-facial arrangements of NPI moieties. The propeller shape arrangement of TAB moiety in 6.1, 6.2, 6.5, 6.6 and 6.7 effectively prevents the aggregation induced emission quenching (AIEQ) and induce strong emission in the condensed state. In the solid state, compounds 6.1, 6.4, 6.5, and 6.6 generate an interesting supramolecular structure via intermolecular C-H--- and C-H---O interactions. No face to face intermolecular π---π interactions were found in the crystal structures of 6.1, 6.4, 6.5, and 6.6. This precludes the excimer formation which can be detrimental to the radiative process in these molecules. The scanning electron microscopy (SEM) images of as prepared samples of 6.1-6.7 clearly indicate that the morphology of these compounds strongly depends on the molecular conformations and number of naphthalimide moieties in the TAB-NPI conjugates. Chapter 7 This chapter deals with design, synthesis and optical properties of novel dimesitylboryl appended perylenediimides. A simple synthetic strategy has been developed for the construction of novel TAB-PDIs conjugates. These conjugates can be conveniently synthesised by condensation of boryl anilines with perylene tetracarboxylic acid anhydride. The incorporation of TAB moiety enhanced the solubility of perylen bisimides in common organic solvents. The PL quantum yield of both 7.1 and 7.2 strongly depends on the excitation wavelength. Lower Pl efficiency observed for 7.1 and 7.2 upon excitation in the boryl dominated absorption region may be due to the photon induced electron transfer form mesityl units of boryl to perylene bisimide moiety. The morphology as well as emission colours of supramolecular architectures of both 7.1 and 7.2 can be modulated by controlling the concentrations of DCM solutions of these compounds. Both the compounds showed selective fluorogenic response for F-1 and CN-1 anions. The simple synthetic strategy reported in this chapter can be conveniently exploited for the construction of TAB conjugates of semiconducting organic anhydrides. Chapter 8 Novel planar chiral Lewis acids 8.3(SP, SS), 1-phosphino-2-borylferrocenes 8.4(SP) and 2-phosphino-1-borylferrocenes 8.4(RP) have been synthesized from a readily accessible ferrocene sulphinate precursor. Adopting a simple synthetic approach and a single precursor, enantiomerically pure SP and RP isomers have been prepared. It would be worthwhile to investigate the catalytic properties of compounds 8.3(SS), 8.4(SP) and 8.4(RP). It would also be interesting to replace the mesityl groups on boron with other electron deficient groups like pentafluorophenyl and 1,3,5-trifluoromethylphenyl to fine tune the Lewis acidity of boron center and to set-up a general route to enantiomerically pure Planar Chiral Frustrated Lewis Pairs (PCFLP’s).

The diploma thesis deals with resonance energy transfer in hydrogel matrix enviroment. In the theoretical part, all the important features of these systems and their components are summarized and all the principles for explaining the method used are described. The work also includes a short literary background research. In the experimental part, the resonance energy transfer was measured in micellar solutions and hydrogels in 0.15 M NaCl medium. The hydrogels were formed on the basis of interaction of the surfactant with the oppositely charged polyelectrolyte. As a positively charged surfactant, carbethopendecinium bromide (Septonex) was chosen and hyaluronan as the negatively charged polyelectrolyte. Perylene with fluorescein and perylene were selected as fluorescent pairs for RET. It has been found that increasing concentration of the acceptor molecule increases the intensity of RET, in other word the rate of acceptor binding to the donor. In the study of fluorescent pair of perylene with DiO was observed, that it was not appropriate to use fluorescence probe DiO at higher concentrations. Experiments were carried out to determine whether RET changes in the time from the point of mixing the donor and acceptor fluorescence probes together. This phenomenon has not been confirmed. In hydrogels, the effect of increasing surfactant concentration and molecular weight of hyaluronan was observed. The resulting analysis showed that the molecular weight of hyaluronan has a significant effect on RET efficiency in hydrogels.

This dissertation focuses on the design, synthesis, and characterization of a variety of organic dyes, semiconducting materials, and surface redox-active modifiers of potential interest to organic-based emerging photovoltaics. A discussion of the materials’ optoelectronic properties, their ability to modify and promote electron transfer through an organic/transparent conducting-oxide interface, and finally their effect on the photovoltaic properties of devices utilizing them as light-harvesters is provided where relevant. The first two research chapters discuss mono-chromophoric asymmetric squaraine-based sensitizers and covalently linked, dual-chromophoric, porphyrin-squaraine sensitizers as light absorbers in dye-sensitized solar cells (DSSCs), in an attempt to address two problems often encountered with DSSCs utilizing this class of near infra-red sensitizers; The lack of panchromatic absorption and aggregation on the surface. Also, this dissertation discusses the design and synthesis of asymmetric perylene diimide phosphonic acid (PDI-PA) redox-active surface modifiers, and reports on the electron-transfer rates and efficiencies across the interface of an ITO electrode (widely used in organic-electronic devices) modified with these perylene diimides. Finally two series of hole-transport materials based on oligothiophenes and benzodithiophenes are reported: optoelectronic properties and preliminary performance of organic photovoltaic (OPV) devices fabricated with them is discussed.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Energy from the sun can be converted to low cost electricity using dye-sensitized solar cells (DSCs). Dye molecules adsorbed to the surface of mesoporous TiO2 absorb light and inject electrons into the semiconductor. They are then regenerated by the reduced redox species from an electrolyte, typically consisting of the iodide/tri-iodide redox couple in an organic solvent. In a solid state version of the DSC, the liquid electrolyte is replaced by an organic hole conductor. Solid state DSCs using 2,2'7,7'-tetrakis-(N,N-di-p-methoxyphenyl-amine)-9,9'-spirobifluorene (spiro-MeOTAD) have reached conversion efficiencies of up to 6 %, which is about half of the efficiency of the best iodide/tri-iodide cells.   Measurement techniques, such as spectroelectrochemistry and photo-induced absorption spectroscopy (PIA), were developed and applied to study the working mechanism of organic dyes in solid state DSCs under solar cell operating conditions. The energy alignment of the different solar cell components was studied by spectroelectrochemistry and the results were compared to photoelectron spectroscopy. PIA was used to study the injection and regeneration processes. For the first time, it was shown here that the results of PIA are influenced by an electric field due to the electrons injected into the TiO2. This electric field causes a shift in the absorption spectrum of dye molecules adsorbed to the TiO2 surface due to the Stark effect.   Taking the Stark effect into consideration during the data analysis, mechanistic differences between solid state and conventional DSCs were found. A perylene dye, ID176, was only able to efficiently inject electrons into the TiO2 in presence of lithium ions and in absence of a solvent. As a result, the sensitiser worked surprisingly well in solid state DSCs but not in liquid electrolyte ones. Regeneration of oxidised dye molecules by spiro-MeOTAD was found to be fast and efficient and spiro-MeOTAD could even reduce excited dye molecules.

Le but de cette thèse était d’auto-assembler des entités triarylamines donneurs d’électrons et capables de s’empiler en fibres conductrices sous l’action de la lumière, avec des entités accepteurs d’électrons de manière à obtenir des hétérojunctions supramoléculaires. Ces objectifs ont été atteints dans des versions dites statiques (distances constantes entre canauxdonneur et accepteur d’électrons) mais aussi dans une version dynamique ou la distance entre unités électroactives change grâce à l’action contrôlée d’un muscle moléculaire intégré. Ces systèmes auto-assemblés fonctionnels ont montré des changements très importants de leurs propriétés optoélectroniques en réponse à des stimuli orthogonaux comme la lumière et le pH. / The aim of this thesis was to self-assemble electron-donating triarylamine units, capable of aggregation into conducting fibers triggered by light, with electron-accepting entities to obtain supramolecular heterojunctions. These objectives were attained, that is in static versions (with constant distances between electron-donating and -accepting channels) and in a dynamicversion wherein the distance between the electroactive units changes owing to the controlled action of an integrated molecular muscle. These functional self-assembled systems showed very important changes in their optoelectronic properties in response to orthogonal stimuli such as light and pH.

Le contrôle de la morphologie de la couche active en optoélectronique organique représente un objectif majeur du fait de son impact sur la stabilité et les performances des dispositifs. En particulier, le degré d'autoorganisation d'un mélange de deux composés à caractère donneur (D) et accepteur (A) d’électrons, ainsi que leurs orientations sont déterminants pour obtenir à la fois un de transfert de charges efficace et des chemins de percolation continus jusqu'aux électrodes. Durant ce travail de thèse, nous avons synthétisé plusieurs séries de co-oligomères à blocs donneur-accepteur capables de s’auto-organiser pour former des lamelles alternées D/A à longue distance. Les co-oligomères présentent une architecture moléculaire de type diade (DA) ou triade (DAD ou ADA), et sont constitués d’une longueur de bloc D variable. Les molécules sont toutes composées d'un bloc A à base de perylène diimide et d'un bloc D contenant les motifs thiophène, fluorène et benzothiadiazole. Une attention particulière a été portée sur l'étude des propriétés optiques, électrochimiques, photophysiques, structurales ou encore opto-électroniques de nos matériaux. En particulier, nous nous avons montré que l’organisation lamellaire était très fortement dépendante de l’architecture moléculaire, puisque seuls les systèmes AD et ADA conduisent à une structuration à longue distance. Par ailleurs, en ajustant la densité électronique au sein du bloc D, nous avons montré qu’il était possible de contrôler à la fois le temps de formation et la durée de vie des états à transfert de charges. Enfin,les premiers résultats de caractérisation du transport de charges et des propriétés photovoltaïques démontrent l’intérêt de ces matériaux dans la réalisation de dispositifs photovoltaïques organiques mono-composants. / In the field of organic opto-electronics, the good control of the active layer morphology in devices represents a major objective to improve the stability and the photovoltaic performances. Especially when blends of selforganizing electron donor (D) and acceptor (A) moieties are combined, their mutual orientation and the degree of supramolecular ordering are determinant in controlling the fundamental energy, the electron transfer processes and the existence of continuous percolation pathways for charge carriers. In this work, we have designed and synthesized different series of donor-acceptor block co-oligomers able toself-assemble in a lamellar structure at very long range. The co-oligomers are made of a dyad (AD) or triad (DAD, or ADA) molecular architecture, and have a variable length of the D block. The A block is constituted of a perylene diimide unit, and the D block of benzothiadiazole, thiophene and fluorene segments. A particular attention was paid on the studies of optical, electrochemical, photophysical, structural and opto-electronical properties. In particular, we showed that the lamellar organization was strongly dependent on the molecular architecture, since only the AD and ADA systems lead to long-range organization. Moreover, by tuning the electronic density along the D block, it has been possible to control both the formation and lifetime of the charge transfer states. Finally, the first results on charge transport and photovoltaic properties demonstrate the high interest of these materials for the elaboration of single component organic photovoltaic devices.