A set of water-soluble 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) derivatives, has been prepared and their spectroscopic properties examined. These dyes can be used as either donor or acceptor in synthesis of through-bond energy transfer cassettes. Sulfonation conditions were developed for several BODIPY dyes to give the mono-sulfonated and di-sulfonated products. Compounds with an aryl iodide could be used for organometallic couplings. Similarly, BODIPYs with an aromatic bromide, but also two chlorine atoms could be replaced via SNAr reactions. The amine sulfonated BODIPY is amenable to couple to biomolecules via acylation reactions. A diazotization/azide reaction sequence was used to convert the amines into azides; the latter may be functionalized via click reactions. Spectral data for these materials indicates they are highly fluorescent probes in aqueous environments. We have also prepared some lipophilic BODIPY derivatives, which can be used for SNAr reactions and make some through-bond, energy transfer cassettes. DichloroBODIPYs can also be used for labeling proteins successfully.

In the development of covalent organic frameworks (COFs), often the scaffold linkers are assumed to be electro- and photoinactive, and this was also to be the case for 2,3,6,7,10,11-hexahydroxytriphenylene, a tritopic linker. However, as demonstrated in the present study, the reaction product of this linker, hexaoxatriphenylene, is electron rich and when connected to a suitable photosensitizer engages itself in an efficient excited-state charge separation process. In the present study, we have employed BF2-chelated dipyrromethenes (BODIPYs) as sensitizers, which are connected to hexaoxatriphenylene through the center boron, rendering paddle-wheel-type structures. Systematic photophysical, electrochemical, computational, and photochemical studies involving pump-probe femtosecond transient spectroscopy have been performed to establish efficient charge separation in these novel supramolecular structures.

Yes / The structural features required for mitochondrial uptake of BODIPY-based optical imaging agents have been explored. The first derivatives of this class of dyes shown to have mitochondrial membrane potential-dependent uptake in both cancer and heart cells have been developed. / Daisy Appeal Charity (Grant: DAhul0211), the University of Hull scholarship, Newcastle University, EPSRC and High Force Research Ltd, EPSRC Fellowship (EP/G005206/1)

BODIPYs são compostos fluorescentes que possuem uma ampla gama de aplicações tecnológicas em diversas áreas do conhecimento, recebendo considerável destaque na literatura, tanto do ponto de vista fotoquímico, quanto sintético. Entretanto, a reatividade química desses fluorórofos ainda não é totalmente compreendida. Neste sentido, neste trabalho utilizou-se a química de sais de diazônio aplicada aos BODIPYs, explorando uma série de perspectivas para diversificação estrutural desses fluoróforos. Como estratégias para a obtenção do BODIPY funcionalizado com o grupo diazo foram testados três diferentes métodos, que envolvem a utilização de NOBF4, NaNO2/HCl e NaNO2/HBF4. O método que envolve a utilização de NOBF4 não levou a obtenção do composto diazotado, no entanto, resultou na obtenção de compostos nitrosilados. Quando utilizado NaNO2/HCl, o composto diazotado foi obtido in situ, seguido pela reação de acoplamento diazóico. Com o método que envolve o uso de NaNO2/HBF4 foi possível obter melhores rendimentos para as reações de acoplamento diazóico, e abriu a possibilidade de novas explorações química dos sais de diazônio-BODIPY / BODIPYs are fluorescent compounds which have a wide range of technological applications in different areas of knowledge. They have remarkable presence in the literature because of their synthetic and photochemical properties. However, the chemical reactivity of these fluorophores are not fully known. Considering this, our study applied the diazonium salts chemistry to BODIPYs aiming to explore the structure diversification of these fluorophores. Three different methods were used to obtain the diazo derivatives of BODIPYs: NOBF4, NaNO2/HCl and NaNO2/HBF4. The method using the NOBF4 instead of afford the diazotized compound as expected, a nitrosylated compound was obtained. When NaNO2/HCl was used, the diazotized compound was obtained in situ, followed by diazo coupling reaction. The best yields diazo coupling reactions were obtained when NaNO2/HBF4 was used. The reactions described in our work showed new possibilities of chemical tractability of BODIPY compounds.

O desenvolvimento de técnicas analíticas, espectroscópicas e de imagem baseadas na detecção da fluorescência está associado com a necessidade por marcadores fluorescentes com variadas características e aplicabilidades. Dentre os diversos marcadores fluorescentes disponíveis, os derivados de borodipirrometenos (BODIPY), descobertos no final da década de 1960, passaram a ser amplamente utilizados desde o final da década de 1980. Esta tese de doutorado se trata de um estudo pioneiro no Brasil, envolvendo a síntese, modificação química e caracterização fotofísica de BODIPYs. Na primeira etapa do projeto métodos de obtenção de BODIPYs foram estabelecidos e aplicados na síntese de uma biblioteca de sondas fluorescentes. O estudo fotofísico dessa biblioteca de fluoróforos nos possibilitou identificar e estudar particularidades de alguns fluoróforos, como o solvatocromismo, halocromismo e ionocromismo. A segunda etapa do projeto envolveu o estabelecimento de métodos de modificação química de BODIPYs visando a diversificação fotofísica e estrutural da biblioteca de compostos. Foram sintetizados BODIPYs reativos que foram submetidos a reações de substituição nucleofílica, Suzuki, Sonogashira, Knoevenagel e arilação direta, levando à obtenção de compostos com propriedades ópticas diversas. Por fim, na terceira etapa do projeto, está descrito o desenvolvimento de novos métodos de modificação química de fluoróforos BODIPY. Foi desenvolvido um método simples de tiocianação direta dessa classe de compostos com bons rendimentos, baseado na utilização de tiocianato de amônio e oxone ®. O escopo e as limitações do novo método de tiocianação foi estudado em BODIPYs com propriedades eletrônicas diversas. Foi mostrada ainda a conversão de BODIPYs tiocianados a derivados tioalquilados com características ópticas particulares. Em conclusão, com esta tese de doutorado foi estabelecida uma linha de pesquisa inovadora envolvendo a síntese e modificação química de uma classe de compostos com ampla aplicação tecnológica. / The development of fluorescence-based analytical, spectroscopic and image techniques is associated with the necessity of fluorescent probes with diverse properties and applications. Among the available fluorescent probes, borondipyrromethene (BODIPY) derivatives, discovered in the late 1960`s, became widely applied since the late 1980`s. This PhD thesis is a pioneering study in Brazil, concerning the synthesis, chemical modification and photophysical characterization of BODIPYs. In the first stage of the project some methods for the synthesis of BODIPYs were stablished and then applied in the development of a library of fluorescent probes. The photophysical study of this fluorophore library enabled us to identify and further study particularities of some fluorophores, such as solvatochromism, halochromism and ionochromism. The second stage of the project involved the establishment of methods for the chemical modification BODIPYs, aiming at the photophysical and structural diversification of the library. Reactive BODIPYs were synthesized and subjected to reactions such as nucleophilic substitution, Suzuki, Sonogashira, Knoevenagel and direct arylation, resulting in the obtainment of compounds with diverse optical properties. Finally, in the third stage of the project, it is described the development of new methods for the chemical modification of BODIPY fluorophores. It was developed a simple and high yielding method for the direct thiocyanation of this class of compounds, based on the use of ammonium thiocyanate and oxone ®. The scope and limitations of the new thiocyanation method has been studied in BODIPYs with different electronic properties. It was also shown the conversion of thiocyanated BODIPYs to thioalkylated derivatives bearing particular optical characteristics. In conclusion, in this PhD thesis an innovative research line involving the synthesis and chemical modification of a class of compounds with broad technological application has been established.

BODIPYs são compostos fluorescentes que possuem uma ampla gama de aplicações tecnológicas em diversas áreas do conhecimento, recebendo considerável destaque na literatura, tanto do ponto de vista fotoquímico, quanto sintético. Entretanto, a reatividade química desses fluorórofos ainda não é totalmente compreendida. Neste sentido, neste trabalho utilizou-se a química de sais de diazônio aplicada aos BODIPYs, explorando uma série de perspectivas para diversificação estrutural desses fluoróforos. Como estratégias para a obtenção do BODIPY funcionalizado com o grupo diazo foram testados três diferentes métodos, que envolvem a utilização de NOBF4, NaNO2/HCl e NaNO2/HBF4. O método que envolve a utilização de NOBF4 não levou a obtenção do composto diazotado, no entanto, resultou na obtenção de compostos nitrosilados. Quando utilizado NaNO2/HCl, o composto diazotado foi obtido in situ, seguido pela reação de acoplamento diazóico. Com o método que envolve o uso de NaNO2/HBF4 foi possível obter melhores rendimentos para as reações de acoplamento diazóico, e abriu a possibilidade de novas explorações química dos sais de diazônio-BODIPY / BODIPYs are fluorescent compounds which have a wide range of technological applications in different areas of knowledge. They have remarkable presence in the literature because of their synthetic and photochemical properties. However, the chemical reactivity of these fluorophores are not fully known. Considering this, our study applied the diazonium salts chemistry to BODIPYs aiming to explore the structure diversification of these fluorophores. Three different methods were used to obtain the diazo derivatives of BODIPYs: NOBF4, NaNO2/HCl and NaNO2/HBF4. The method using the NOBF4 instead of afford the diazotized compound as expected, a nitrosylated compound was obtained. When NaNO2/HCl was used, the diazotized compound was obtained in situ, followed by diazo coupling reaction. The best yields diazo coupling reactions were obtained when NaNO2/HBF4 was used. The reactions described in our work showed new possibilities of chemical tractability of BODIPY compounds.

O desenvolvimento de técnicas analíticas, espectroscópicas e de imagem baseadas na detecção da fluorescência está associado com a necessidade por marcadores fluorescentes com variadas características e aplicabilidades. Dentre os diversos marcadores fluorescentes disponíveis, os derivados de borodipirrometenos (BODIPY), descobertos no final da década de 1960, passaram a ser amplamente utilizados desde o final da década de 1980. Esta tese de doutorado se trata de um estudo pioneiro no Brasil, envolvendo a síntese, modificação química e caracterização fotofísica de BODIPYs. Na primeira etapa do projeto métodos de obtenção de BODIPYs foram estabelecidos e aplicados na síntese de uma biblioteca de sondas fluorescentes. O estudo fotofísico dessa biblioteca de fluoróforos nos possibilitou identificar e estudar particularidades de alguns fluoróforos, como o solvatocromismo, halocromismo e ionocromismo. A segunda etapa do projeto envolveu o estabelecimento de métodos de modificação química de BODIPYs visando a diversificação fotofísica e estrutural da biblioteca de compostos. Foram sintetizados BODIPYs reativos que foram submetidos a reações de substituição nucleofílica, Suzuki, Sonogashira, Knoevenagel e arilação direta, levando à obtenção de compostos com propriedades ópticas diversas. Por fim, na terceira etapa do projeto, está descrito o desenvolvimento de novos métodos de modificação química de fluoróforos BODIPY. Foi desenvolvido um método simples de tiocianação direta dessa classe de compostos com bons rendimentos, baseado na utilização de tiocianato de amônio e oxone ®. O escopo e as limitações do novo método de tiocianação foi estudado em BODIPYs com propriedades eletrônicas diversas. Foi mostrada ainda a conversão de BODIPYs tiocianados a derivados tioalquilados com características ópticas particulares. Em conclusão, com esta tese de doutorado foi estabelecida uma linha de pesquisa inovadora envolvendo a síntese e modificação química de uma classe de compostos com ampla aplicação tecnológica. / The development of fluorescence-based analytical, spectroscopic and image techniques is associated with the necessity of fluorescent probes with diverse properties and applications. Among the available fluorescent probes, borondipyrromethene (BODIPY) derivatives, discovered in the late 1960`s, became widely applied since the late 1980`s. This PhD thesis is a pioneering study in Brazil, concerning the synthesis, chemical modification and photophysical characterization of BODIPYs. In the first stage of the project some methods for the synthesis of BODIPYs were stablished and then applied in the development of a library of fluorescent probes. The photophysical study of this fluorophore library enabled us to identify and further study particularities of some fluorophores, such as solvatochromism, halochromism and ionochromism. The second stage of the project involved the establishment of methods for the chemical modification BODIPYs, aiming at the photophysical and structural diversification of the library. Reactive BODIPYs were synthesized and subjected to reactions such as nucleophilic substitution, Suzuki, Sonogashira, Knoevenagel and direct arylation, resulting in the obtainment of compounds with diverse optical properties. Finally, in the third stage of the project, it is described the development of new methods for the chemical modification of BODIPY fluorophores. It was developed a simple and high yielding method for the direct thiocyanation of this class of compounds, based on the use of ammonium thiocyanate and oxone ®. The scope and limitations of the new thiocyanation method has been studied in BODIPYs with different electronic properties. It was also shown the conversion of thiocyanated BODIPYs to thioalkylated derivatives bearing particular optical characteristics. In conclusion, in this PhD thesis an innovative research line involving the synthesis and chemical modification of a class of compounds with broad technological application has been established.

Electrochemical and electrogenerated chemiluminescence properties of the BODIPY (boron dipyrromethene) dyes are presented. Some specific features of the BODIPY dyes are obtained and described in the current dissertation. Separation of around 1.0-1.2 V is noticed between two oxidation and reduction waves for one center which is very different from 0.5 V seen for the polycyclic hydrocarbons. Cathodic and anodic stability is shown to depend upon absence or presence of certain degree of substitution. Different ways of electrochemical dimerization are explored and compared with the chemical dimerization. Photophysical and electrochemical properties of monomer, chemically synthesized dimer, trimer and polymer are described and the characteristic features determined. / text

Luminescent boron containing materials find numerous applications in modern technologies such as display/lighting, bio-imaging and sensing. Thus, investigations of structure-property relationships in organic luminescent compounds to understand their molecular and bulk properties are of fundamental importance. The main thrust of this thesis is the development of facile synthetic routes for boron containing novel polyads and study their structure-property correlations and to utilize this information to design functional materials with desired properties such as multiple emission, bio imaging, anion sensing and organic photo voltaic characteristics. This thesis contains seven chapters and the contents of each chapter are described below. Chapter 1 This chapter is a concise overview of the recent developments in the chemistry of boron based molecular systems such as triarylborane and BODIPYs. This chapter also highlights the basic nature of broad emissive materials. In addition, an advance in the frontier areas such as bio imaging is discussed in brief. Chapter 2 This chapter describes the structure and optical properties of a new triad (Borane-Bithiophene-BODIPY) 1. Triad 1 exhibits unprecedented tricolour emission when excited at borane centred high energy absorption band and also acts as a selective fluorescent and colorimetric sensor for fluoride ion with ratiometric response. The experimental results are supported by computational studies. Chapter 3 Two fluorescent compounds with similar absorption profiles and complementarily emissive properties can be regarded as the ideal couple for the generation of white-light. Two structurally close and complementarily fluorescent boron based molecular siblings 2 and 3 were prepared. The luminescence properties of individual triads were modulated to an extent to complement each other by controlling the intramolecular energy transfer in triads by fine-tuning the dihedral angle between fluorophores in 2 and 3. A binary mixture of 2 and 3 emitted white-light. Chapter 4 This chapter deals with a straight forward strategy for the generation of white-light emission in aqueous media. Using a blue-emissive AIE-active (aggregation-induced emission) 1, 8-naphthalimide- based sensitizer and a boron-dipyrromethene based red emitter as a dopant, water dispersible nanostructures with tunable emission features are produced. The white-light emissive (WL) nano-aggregates are stable at neutral pH and have been elegantly utilized for four-colour cell imaging (including near- infrared imaging). Chapter 5 This chapter describes the design and development of a NIR emitting triarylborane decorated styryl-BODIPY (4) via a facile synthetic route. Incorporation of TAB entities results in a significantly red shifted broad emission in 4 (compared to compound M3 which is devoid of TAB unit). The near coplanar orientation of Ar3B planes and BODIPY core results in a highly efficient (TAB to BODIPY) EET process in 4. Conjugate 4 acts as a highly selective and sensitive fluoride sensor with naked eye visual response as well as ratiometric fluorescent response. The dual emission in fluoride bound 4 possibly results from the restricted partial TAB to BODIPY energy transfer. Chapter 6 This chapter describes how the energy of transitions of the broad emissive molecular triads can be fine-tuned by judiciously changing the spacer oligothiophene length. A series of triarylborane and BODIPY conjugates (TAB-π-BODIPY) has been designed, and synthesized by a combined strategy of changing the connection mode between the two units, extending the conjugation size by introducing terthiophene, quaterthiophene, and pentathiophene units. The electrochemical and photophysical behavior of these conjugates were investigated. The experimental findings were rationalized by density functional theory calculations. Chapter 7 This chapter describes design and development of boron based novel electron acceptor BDY for the bulk-heterojunction solar cell. The electron mobility values of BDY was found to be of the order of standard PCBM. Bulk-heterojunction was fabricated using BDY as the electron acceptor layer. The power conversion efficiency of the newly developed solar cells with BDY as electron acceptor is much higher than the value obtained for standard cells with PCBM as the electron acceptor.

Fluorescence microscopy offers the opportunity to image noninvasively biological samples in real time. However, the phenomenon of diffraction limits the resolution of conventional fluorescence microscopes to submicrometer dimensions in both the horizontal and vertical directions. This limitation can be overcome by photoswitchable fluorescent probes able to undergo reversible saturable optically linear fluorescence transitions (RESOLFT). In this study, firstly, a photoswitchable fluorescent probe based on BODIPY fluorophore and Spiropyran photochrome were designed and its photophysical and photochemical properties were investigated in organic and aqueous environments. Also, its imaging with patterned illumination was showed by trapping them in PMMA matrix. Secondly, photochromic [1,3]oxazines with different substituents as well as polymers incorporating them were synthesized and their photochemical and photophysical properties were investigated. Thirdly, to improve the switching speeds and fatigue resistance of the BODIPY-Spiropyran conjugate, the photochromic part was replaced by [1,3]oxazines and dyads incorporating BODIPY fluorophore and [1,3]oxazine photochromes were synthesized. Lastly, a new strategy was designed to switch the fluorescence of fluorophores by a modular approach. It is based on photoinduced elongation of the absorption wavelength of a fluorescent chromophore with the aid of an appended photochromic auxochrome.