Theses supervised by Prof. Dr. Engin Umut Akkaya
42 theses · İhsan Doğramacı Bilkent University
Terapötik uygulamalar için hedeflenmiş fotoduyarlaştırıcılar ve kontrollü singlet oksijen üretimi
Photodynamic therapy of cancer plays a pivotal role due to its many superior features and potential. Considering the pathways for improving the practice of PDT of cancer is gradually increasing, enhancing the selectivity of photodynamic action is an obvious choice. Being the source of reactive oxygen species in the body, mitochondrion is one of the most proper organelles to target. There is plethora of findings suggesting that triphenlyphosphonium cation is a very favorable mitochondria targeting agent. Another aspect of PDT requires creation of smart molecules which respond to either the increased temperature or ion concentrations in order to release 1O2. Cyclic endoperoxides of naphthalene and anthracene could help in achieving the desired objective of storing 1O2 and regenerating it again when appropriate conditions meet. The half-life cycloreversion of 1,4-Dimethylnaphthalene could be changed at least 100-fold when 2-position of the naphthalene is sterically hindered. Taking advantage of the fact that fluoride ions' silicophile nature, a novel perspective for drug design can be proposed. In the final project, a certain level magnetic hyperthermia, large enough to cause endoperoxide cycloreversion, but not large enough to cause necrotic death, is being sought after. Controlled generation singlet oxygen by the application of tissue penetrating alternating magnetic fields is the ultimate goal for that project.
Mekanokimyasal yöntemlerle singlet oksijen üretimi
Singlet oxygen is a short-lived reactive species which is involved a number of biochemical processes and implicated as the primary photo-generated cytotoxic agent in photodynamic therapy (PDT) of cancer. Precise chemical control of singlet oxygen generation and or storage is therefore of immense interest. In this particular study, the possibility of mechanochemical release of singlet oxygen in cross-linked polymers carrying anthracene 9,10-endoperoxides was explored. 9,10-Diphenylanthracenes are stable at room temperature but undergo thermal cycloreversion when heated to produce singlet oxygen. Thus, a cross-linked polyacrylate was synthesized, incorporating anthracene-endoperoxide modules with chain extensions at the 9,10-positions. Previously in our lab, thermal lability of the anthracene endoperoxides were shown when attached to gold nanorods. In this work, it was demonstrated that on mechanical agitation in a cryogenic ball mill, fluorescence emission due to anthracene units in the polymer is enhanced, with a concomitant generation of singlet oxygen as proved by detection with a selective probe, SOSG. Also, a cross-linked polyacrylate and a PDMS elastomer incorporating anthracene-endoperoxide modules with chain extensions at the 9,10-positions were synthesized as the polymeric matrix for a better manifestation of mechanochemical process.
Terapötik otomatlara gidiş ve hipoksi ile aktive olan singlet oksijen üreticileri
Photodynamic therapy (PDT) is a treatment modality depends on the efficient generation of singlet oxygen (1O2) through excitation of a particular chromophore (sensitizer) followed by an energy transfer to the dissolved oxygen in tumor tissues. Cytotoxic singlet oxygen and other secondary products (reactive oxygen species, ROS) are responsible for the apoptotic and necrotic deaths of the tumor cells. We present a molecular 1:2 demultiplexer (DEMUX) which acts as a "terminator" automaton: once powered up by photoexcitation, the agent releases singlet oxygen to kill cancer cells. Once the cancer cells start apoptosis, the agent interacts with the exposed phosphatidylserines on the external leaflet, and autonomously switches to the signaling mode, turning on a bright emission signal, and turning off singlet oxygen generation. So, the output can switch between singlet oxygen and a confirmatory fluorescence emission for apoptosis, which are mutually exclusive in this design. The automaton that we present here, is based on logic gate considerations and a sound photophysical understanding of the system, and should be a very convincing case of molecular logic with a clear path of progress towards practicality. In another project, we are very much interested in transforming PDT into a more manageable and broadly applicable therapeutic protocol. Our approach to achieve that is to separate photosensitization event from the delivery of singlet oxygen, which is the primary cytotoxic agent of PDT. Thus, a storage compound (endoperoxide) for singlet oxygen has to be designed, which can react with molecular oxygen under typical photosensitization conditions, and then the metastable compound has to be transferred to the tumor site which would release its cargo in response to a chemical or enzymatic cue. This approach assumes that singlet oxygen produced stoichiometrically (as opposed to catalytically through photosensitization) by the chemical transformation of the carrier molecule, would be enough to trigger apoptotic response in cancer cells.
Bodıpy boyasının moleküler sensörler, ışık hasat edebilen sistemler ve fotodinamik terapi uygulamaları için rasyonel tasarımı ve sentezi
BODIPY dyes have been addressed in many applications due to highly important features. These unique properties can be summarized as high photostability, high extinction coefficient, easy functionality, etc. Thus, tremendous studies have been published and, ion sensing, photodynamic therapy, dye-sensitized solar cells and light harvesting are some of the areas that BODIPY dyes have been utilized. In this thesis, BODIPY dyes were functionalized to be used for different concepts. In the first study, the main purpose was to seek for ion signaling differences of two isomeric tetra-styryl BODIPY dyes with charge donor ligand located at 1,7 versus 3,5 positions. Second work focuses on the light harvesting concept with the use of tetra-styryl BODIPY derivatives. Third study describes the coupling of energy transfer with internal charge transfer to monitor the alterations in intensity ratios, so, dynamic range of the fluorescent probe is improved. Design and synthesis of BODIPY dyes for detection of biological thiols in aqueous solution both chromogenically and fluorogenically was given in fourth study. Another biologically important molecule, hydrogen sulfide is selectively detected via BODIPY-based probe and depicted in the fifth study. In the sixth work, persistent luminescent nanoparticles are attached to BODIPY-based photosensitizer to activate the photodynamic action.
Fotodinamik aksiyon için fotoduyarlaştırıcılar ve moleküler demultiplekser modüllerinin sentezi
Photodynamic therapy (PDT) is a new therapeutic methodology that uses light as a distinguishing tool for the treatment of diseased cells. In recent years PDT has become one of the most preferred therapies because it is innocent for the healthy cells and tissues while diagnosing and curing the malignant cells and tissues. Bodipy is one of the most favorite fluorophore in this field due to its excellent chemical and physical properties. Logic gates are widely used in modern technology as the fundamentals of logical operations for the development of science. The progressive advances leads to the emergence and growth of molecular logic gates. Molecular logic gates can be used for the diagnosis and therapies of disease which are originated from the heredity. In addition, they occupy an important place in the theoretical and practical use of photodynamic therapy. In the first part of my thesis, we designed and synthesized a calix[4]arene-Bodipy conjugate molecule as a carrier for the photodynamic therapy agents. It is an amphiphilic delivery molecule that is utilized for the curing of tumor tissues. In the second part, we synthesized modules for molecular logic gate function, DEMUX (demultiplexer), serving as a theranostic device which selects either singlet oxygen channel or energy transfer between the modules depending on the inputs. The superiority of the project is that it serves a realistic pathway for the PDT. Keywords: Calixarenes, Logic gates, photodynamic therapy, demultiplexer
Biyolojik tiyollerin tanısı ile fotosensitizör aktivasyonu ve 1,2-dioksetan temelli kemilüminesan problar
Biologically important biothiols like Cystein (Cys), Homocystein (Hcy) and Glutathione (GSH) are vital for the maintenance of cellular redox status and alterations in their levels is linked to a number of severe diseases such as AIDS, cancer and Alzheimer's therefore the design and synthesis of nitroolefin functionalized bodipy dyes responding to biological thiols by both absorbance and emission changes have been accomplished. Through the incorporation of hydrophilic groups, bright signaling of biothiols in the longer wavelength region of the visible spectrum is deemed to operate in biological environment. With this knowledge, bioconjugation of the nitroolefin functionalized dyes with thiol groups like those belonging to cysteine residues on proteins has been proved via large spectral changes and targeted to visualize dynamics of proteins, cell-cell interactions, mechanisms of life cycles of proteins. Hence, the result suggests that nitroolefin functionalization of BODIPY dyes is a promising way to sense biological thiols and hence labeling proteins having thiol groups. Since GSH plays vital roles in the oxidative stress exists within the cells and thus, high concentration of it is the indication of cancer development, design and synthesis of cancer related parameter based activation of bodipy based photosensitizers have been achieved to enhance spatiotemporal selectivity in photonic sensitization of dissolved molecular oxygen and thus, improves the potential and practice of photodynamic therapy and their effectiveness are validated by cell culture studies. Chemiluminescence in principle can provide a rapid, qualitative and/or quantitative test for analytes of interest; because of that synthesis of novel probes for the sensing of biologically important (fluoride) anion have been devised to combine the power of chemiluminescence and self immolative amplifiers which offers a chemical avenue for enhancing the signal produced in response to a given analyte. Through the development of chemiluminogenic perspective for sensing of palladium ions, rapid and selective response of probe to palladium ions with regardless of their charge in aqueous environment have been accomplished. Considering the convenience of the methods and substantial results, we are confident that other probes combining the power of chemiluminescence will emerge.
Biyolojik tiyollerin floresan tayini ve aksiyal kiral bodipy türevleri ve fotodinamik etki için alternatif yollar ile singlet oksijen üretimi
Calorimetric and luminescent detection of biological thiols namely cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) have attracted great interest due to the their biological significance. There are many reported fluorescent probes for Cys and Hcy, however selective probe designs for GSH remained elusive. We represented in thesis (Chapter 3) a BODIPY based selective fluorescent probe for the in vitro detection of GSH in cancer cell lines. Photodynamic therapy (PDT) is one of the promising and developing treatment modality for certain indications. Therapeutic action is achieved by the generation of cytotoxic singlet oxygen (SO). Most critical compartment of SO production pathway is the sensitizer molecule. In order to get effective inter-system crossing, which is highly needed for singlet oxygen generation, common strategy is to incorporate heavy atoms on sensitizers. However, presence of heavy atoms increases the dark toxicity that is not desired in clinical applications. In Chapter 4, we are introducing a new concept for activatable heavy atom free sensitization of PDT by designing novel orthogonal BODIPY derivatives and detailed computational analysis of this new concept. While dealing with orthogonal BODIPYs, we synthesized for the first time two axially chiral BODIPY derivatives and characterized the enantiopure products, which holds great promise for enantioselective sensing applications (Chapter 5). PDT has two major problems, which are light penetration depth of the incident light and the hypoxia. These two restrictions are addressed in chapter 6, by combining gold nanorods and aromatic endoperoxides.
Trimer dik bodipy yapılarının dizayn, sentez ve karakterizasyonu ve singlet oksijen algılayıcısının gelişımi
Several methods of fighting cancer have been proposed over the years after it was discovered. Photodynamic therapy (PDT) has been part of these methods for many years therefore; too much financial effort has been spent on this field. Since PDT relays on three important components namely: Sensitizer, molecular oxygen and light, our group has worked and published several photosensitizers derived from BODIPY over the years. In this thesis two different ideas to be used in PDT are introduced. First, Heavy atom free orthogonal BODIPY trimmers are introduced for the first time in literature and they are believed to work according to DS-TR principle. Effective singlet oxygen productions were obtained up to 0.53 quantum yields. The second topic is the use of BODIPY and 1,3-DiphenylIsobenzofuran hybrids as a singlet oxygen sensor. This sensor is meant to work based on PeT and ICT mechanisms. No further experimental methods were applied to this molecule after synthesis however; we intend to use it for in-vivo singlet oxygen experiments in the future.
Tek adımda kovalent bağlarla kendiliğinden bir araya gelen enerji transferi sistemi
Light harvesting mechanisms include absorption of energy by donor and transfer of the absorbed energy to acceptor. The aim of this process is the channeling of the light at certain wavelength. In this study, energy transfer process was sustained by BODIPY based Förster type light harvesting cascade. The donor and acceptor units of the cascade were synthesized to be combined by self-assembly. Passerini reaction was used in the assembly of the three units. Designed molecule consists of three moieties: BODIPY, monostyryl- BODIPY and distyryl-BODIPY. The expected process of energy transfer starts with the absorption of light at around 502 nm and ends with the emission at around 674 nm. The spectral overlap between donors and acceptors were shown. Under the light of the results, the designed molecule is promising to work as an effective energy transfer cascade.
Bodipy tabanlı fotoindüklemeli elektron transferi sistemleri aracılığıyla homojen hidrojen fotojenerasyonu
The key technology to fulfill the energy needs in the future is the generation of fuels by harvesting solar energy. Due to high abundance and low prices of cobalt, water-splitting (based on cobalt) method has received a lot of attention compared to noble metals. Several times cobaltoxime based catalysts were studied for proton reduction. In this project, our aim was to produce a homogeneous photocatalytic system for photogeneration of hydrogen with high efficiency. To do so, we synthesized ten integrated molecules in which we are making use of the highly quantum efficient and photostable BODIPY chromophore. After the synthesis and characterization of target molecules, we achieved to demonstrate hydrogen evolution with five of our molecules.
Altın nanoparçacıkların plasmonik ısıtılması ile singlet oksijen üretimi
Photodynamic therapy (PDT) is the up-and-coming and developing methodology in order to treat various cancer tissues. The success of therapeutic action is directly related to the presence of cytotoxic singlet oxygen (SO) in tumor tissues. However, the feasibility of PDT is bounded by two major factors, hypoxia and the requirement of incident light penetration through cancer tissue. With these considerations, we have combined aromatic endoperoxides and gold nanorods so as to accomplish the possible restrictions. In this project, we synthesized and characterized both PEGylated anthracenic endoperoxides and gold nanorods separately and then further characterization was achieved for the combination of gold nanorods and aromatic endoperoxides. We have successfully proved that the thermal decomposition of endoperoxide molecule was carried out by irradiation of gold nanorods that resulted in the generation of both singlet and molecular oxygen.
Fotodinamik terapi için kızıl ötesi ışığı soğurabilen yeni fotoduyarlaştırıcı ve ağır atom içermeyen fotoduyarlaştırıcıların tasarlanması
Photodynamic therapy (PDT) is a promising and emerging noninvasive treatment modality for the treatment of a great number of malignant and non-malignant diseases. Therapeutic strategy in PDT is performed by combining a photosensitizer which can potently and specifically kill diseased cell and a light source, preferentially near-IR light (650-800 nm). In spite of the fact that numerous studies have been published and notable progress has been made in tumor biology and photochemistry which let us to design novel therapeutic agents, the number of the new therapeutic agents which have been recently got approval for clinical application are relatively low. We aimed to produce novel photosensitizers. In the chapters 3, 4 and 5 BODIPY dyes which are amenable to functionalization have been used to produce a novel series of BODIPY-based photosensitizers. We synthesized and characterized a series of novel BODIPY-based photosensitizers. The first part describes novel near-IR BODIPY-based photosensitizers. In the second part, the main goal was to design and synthesize heavy atom free BODIPY-based photosensitizers. In this respect, a new modification of the BODIPY dyes, novel orthogonal BODIPYs were synthesized and their computational analysis were done. A cell culture assay with cancer cell lines was performed in order to demonstrate photocytotoxicity of the orthogonal BODIPY. The third study underlines the importance of micelle-embedded BODIPY-based photosensitizers for photodynamic therapy.
TERMAL ENDOPEROKSİT DEKOMPOZİSYONUNDAKI ÜRETİM HIZININ KİMYASAL MODÜLASYONU & HİPERFOSFORİLE OLMUŞ TAU PROTEİNLERİNİ ALGILAYABİLEN ÖZGÜN FLORESAN DUYAÇLARI
Chemical control over singlet oxygen generation is an open to improvement because of the importance of this reactive species in biological systems. In the first project, we aimed to synthesize a silylated 1,4-dimethylnaphthalene endoperoxide derivative which is expected to release singlet oxygen on thermolysis at a relatively slow rate at room temperature. Upon the deprotection of the silyl units with fluorine ions, it is expected it to release singlet oxygen at a much higher rate, giving rise to a control over the release of the product. The absorption and the fluorescence measurement with a trap molecule which consumes the generated singlet oxygen reveals promising results for the future work for the control of singlet oxygen generation rates. In the second part of this thesis, we focused on the synthesis of a novel fluorescent sensor of a BODIPY derivative which is capable of sensing Zinc cations. The zinc complex is also expected to have a further usage for the sensing of hyperphosphorylated tau proteins, which are commonly produced in the brains of people with Alzheimer's disease. With this, it has a potential usage in the field of early detection of Alzheimer's disease.
Multimodlu tedavi uygulamalarına yönelik bodıpy türevlerinin sentezi
Photodynamic therapy (PDT) is a promising and developing strategy to treat various types of cancers. Either on its own, or combined with surgical interference, it provides easy treatment without destructive side effects of chemotherapy. Its success is straightly dependent on the presence of singlet oxygen (SO) in the tumor tissues. Upon the activation of the photosensitizer, SO gets produced, harming the surrounding tissues. The destructive effect can be increased by a simultaneous treatment with a cytotoxic cancer drug. In this project, we have combined a BODIPY photosensitizer and a Camptothecin (CPT) drug moiety with a (Z)-1,2-bis(alkyl-thio)ethane linker to produce a macromolecule with higher destructive power for tumors. Upon irradiation with a light source, it is expected of the BODIPY sensitizer to convert triplet ground state oxygen to singlet excited state, which then would react with the linker to release CPT.
Metal iyonu salımı ve moleküler mantık devrelerinde sinyalizasyon
Mimicking the biological structures is one of the main goals of the natural sciences, because processes are well-organized in nature despite its amazing complexity. On account of this, releasing metal ions at molecular level is a crucial topic owing to similar process in living organisms. In this thesis, we designed novel cage compounds for this purpose. Our novel cage molecule is activated with near-IR light while almost all of the cage compounds in the previous literature function in the UV region. Consequently, it is appropriate for using in biological systems. Release of zinc ions that has critical roles in human body successfully achieved by our novel compound in Part 2 of the thesis work. Molecular logic concept is one of the promising areas of chemistry. Today, electronic devices consists of silicon based circuits that process information by using binary logic. Molecular logic offers alternative for silicon based devices. Using molecules to process data is a promising idea in the fields from electronics to biotechnology. In part 3, we proposed AND gate whose inputs are pH and glutathione while the response is singlet oxygen which can be used to destroy cancer cells. It is possible to process much complicated information by combining more than one logic gate. In first part of the thesis study, we designed modular molecular logic gates by cascading of three logic gates via metal ion signals. In the last part, a fluorescent chemosensor was proposed for dopamine molecule, which is crucial in a number of biological processes at the human body. Keywords: molecular logic gate, cage compounds, fluorescence, glutathione, photosensitizer, metal ion release, BODIPY, dopamine.
BODIPY türevli singlet oksijen sensörünün sentezi ve karakterizasyonu
Singlet oxygen is a biochemically produced reactive species, which can trigger various cellular responses. It is also produced by photosensitization by the intermediacy of photosensitizer therapy of cancer. Real-time imaging of singlet oxygen is very important to assess the progress of cellular changes leading to apoptosis. We targeted a long wavelength dye, which responds to singlet oxygen with a change in emission color. Color change in emission is particularly important, as it allows internal referencing. Keywords: Bodipy, Photodynamic therapy, singlet oxygen sensor
Sentetik uygulamalar için singlet oksijen doldurulabilir kaynaklar olarak silika kaplı demir oksit nanoparçacıklar
In the rapidly developing world of synthetic chemistry, there is a constant need for high-efficient catalyst. Besides this, reusable and easily removable catalysts are highly desired to reduce costs for environmentally friendly synthesis for both synthetic and manufacturing requirements. Magnetic nanoparticles (MNPs) are promising candidates for effortlessly removable structures due to their ability of being removed by magnetic field. Iron oxide nanoparticles have a well distin- guished place among MNPs since they have unique properties and they can be prepared and functionalized easily. Combination of photosensitizers with MNPs is a new approach for synthetic applications due to the fact that singlet oxygen is a reactive specie for various types of reactions. Herein, BODIPY with 2-pyridone moiety on silica coated iron oxide nanoparticle is designed as a magnetically removable nanostructure that can generate, store and release singlet oxygen. The efficiency is studied by the oxidation of organic sulfides to sulfoxides since they are at the core of many biological processes. Furthermore, this design can produce recyclable and reusable catalysts for additional transformations with high efficieny.
Çok özellikli etmen aracılığı ile singlet oksijen üretimi, saklanması ve iletilmesi
Photodynamictherapy(PDT)relies on the photosensitized generation of sin- glet oxygen(by consuming dissolved oxygen)within tumor tissues whose oxygen level is already low enough to make this treatment self-limiting.In certain ap- plications, hypoxia induced by photosensitizer is minimized by introducing light intermittently(fractional PDT)in order to allow time for the replenishment of cellular oxygen,resulting in more effective treatment.In this particular study, we demonstrated that a photosensitizer with an attached 2-pyridone module to halogenated di-styryl BODIPY would be useful in fractional PDT.Upon illumi- nation of photosensitizer(PYR)with a light at specific wavelength i ntherapeutic window the endoperoxide of 2-pyridone is generated along with singlet oxygen. During the tim erequired for replenishment of cellular oxygen the endoperoxide undergoes cycloreversion to produce singlet oxygen,regenerating the 2-pyridone moiety.Such mechanism enables continuation of photodynamic process in the dark, resulting improved fractional photodynamic therapy drug validated by cell- culture studies in vitro.
Yeni BODIPY bileşikleri ve supramoleküler topluluklarıyla enerji transferi, fotoduyarlaştırma ve algılama
Fluorescent dyes have been used for decades in many applications due to their versatility, sensitivity and many other useful properties. Since their discovery in 1968, BODIPY dyes have come forward and have been used in many fields of research such as photodynamic therapy, anion/cation sensing, dye-sensitized solar cells. In this thesis, novel applications of fluorescent dyes, mainly based on BODIPY fluorophores are reported. In the first project, a photosensitizer derived from erythrosine attached to a luminol derivative is presented. The main purpose was to achieve photosensitization without requiring external excitation with light. In another project, we synthesized and characterized a series of heavy atom substituted BODIPY based photosensitizers. In a related study, the photophysical properties of a BODIPY based chemosensor substituted with benzo-21-crown-7 units were studied in the presence of various -diamino alkanes. Then, we designed a BODIPY based probe sensitive to bioreductive conditions known to be prevalent in hypoxic cancer cells. In the final chapter, we present a mechanically interlocked energy transfer cassette consisted of a distyryl-BODIPY acceptor and two donor units.
Boron dipirin türevlerinde ışık hasatı ve etkin enerji transferi ve boyar madde uyarımlı güneş pillerinde potansiyel kullanıma yönelik türevlendirme
In bichromophoric supramolecular systems light is harvested by antenna components and excitation energy is channeled into an acceptor component. We have designed and synthesized novel energy transfer cassettes which are based on boradiazaindacene (BODIPY) units. Facile synthesis of long wavelength absorbing distyryl BODIPY dyes has been applied successfully in this study. In the first part of the thesis, efficient energy transfer from energy donor BODIPYs to long wavelength absorbing distyryl BODIPY core was demonstrated. To observe the antenna effect quantitatively, we have designed the cassettes with an increasing number of energy donor components. Based on these observations, in the second part of the thesis, we have introduced a light-harvesting photosensitizer for dye-sensitized solar cell (DSSC) purposes. The target molecule absorbs in visible and near-IR region and energy transfer is demonstrated successfully. Our design appears to be highly promising for DSSC.
Yeni BODIPY-temelli fotodinamik terapi sensitizörü taşıma amaçlı kovalent olmayan SWNT türevlendirmesi ve dendritik ışık hasadı sistemlerinin tasarım ve sentezi
Photodynamic therapy (PDT) is a non-invasive method used for the treatment ofa number of diseases including certain cancers and some cardiovasculardiseases. Photodynamic action depends on absorbance of photosensitizer (PS) innear IR region of the spectrum and subsequent generation of cytotoxic singletoxygen in the vicinity of the PS. Carbon nanotubes are widely used forbiomedical applications due to their inertness, biocompatibility, cellularinternalization, facile and multi-modification. We have synthesized andcharacterized novel water soluble boradiazaindacene (BODIPY)-based PS, noncovalentlyattached on to the single wall carbon nanotube (SWNT). We haveobserved that near infrared absorbing photosensitizer preserve its singlet oxygengeneration capability upon adsorption on SWNT. We have demonstrated thatSWNTs can be used as the delivery vehicle of PS for the use in PDT. In thesecond part of this research, multichromatic cascade-type light harvestingBODIPY dendrimers were synthesized and highly efficient energy transfer wasobserved. Successful channeling of energy in a predefined region of thedendrimer was revealed.
Stiril-bodipy türevlerınde PET ve ICT mekanizmalarının seçici kontrolü: Moleküler mantık devreleri ve metal katyonları için floresans sensörlerde uygulamalar
Recent developments in the Bodipy chemistry, provided new opportunities for modification of this chromophore which, in turn, using appropriate metal-ligand pairs, allowed the control and manipulation of PeT and ICT mechanisms. Exploiting these mechanisms, we demonstrated that photophysical properties of Bodipy can be shaped as desired using metal cation modulators to obtain absorbance signals in accordance with a digital half-adder circuit. In addition, another Bodipy derivative with a simple and rational design, shown to have emission signals equivalent to AND operation in Boolean logic. A molecular three-input AND gate was also synthesized taking the advantage of differential binding affinities of metal cations for different ligands. Our work proves that, with careful design, photophysical properties of a single chromophore can be modified as desired. Hence molecular logic gates, and even molecules performing more complex logic operations can be obtained using metal cations as non-annihilating logic inputs.
Boyar madde uyarımlı güneş pilleri için yeni duyarlaştırıcıların sentezi ve karakterizasyonu
Increasing concerns about the global warming and energy demand force scientists to find out new source of energy supply. Among possible energy sources, solar cells are promising candidates. Production costs unfortunately restrict the usage of these cells. Cheaper and environment friendly dye sensitized solar cells (DSSCs) appear to be successful alternatives to more widely used traditional semiconductor based designs. However, most people would agree that, there is still room for improvement for a few components of a typical DSSC. This is perhaps more apparent for the electrolyte, and the sensitizer dye component itself.In this study, we targeted novel Boradiazaindacene (Bodipy) sensitizers which were studied in two types of DSSCs; liquid electrolyte based (Gratzel type) and solid state DSSC. Six different sensitizers were synthesized and characterized. Effects of design and electrolyte type on solar light to electricity conversion efficiency were investigated.We have demonstrated that Bodipy dyes, through rational design, yield promising new materials in Gratzel type dye sensitized solar cells. Their applicability in solid state electrolyte regime offers additional opportunities for practical applications. Bodipy sensitizers hold significant promise as they can be derivatized as desired and the absorption peaks can be moved along the visible and near IR region.
Hacimli gruplar kullanılarak katı hal emisyonu olan bodipy boyarmaddeleri ve disitiril boyar madde bazlı çinko iyonları için seçici ve duyarlı orantısal yakın ınfrared floresans probu
Dyes having solid state fluorescence are playing an important role for organic light emitting devices (OLED), optoelectronic devices and photoelectric conversion. However, emissive solids are not common because of the quenching resulting from the packing. With these considerations, we have synthesized and characterized novel boradiazaindacene BODIPY-based dye with bulky substituents (3,5-di-tert-butylphenyl) to prevent ?-? stacking of the chromophore. We have succesfully demonstrated that by simple modulation of BODIPY core with very bulky groups lead us to have a bright emissive compounds in solid state. In the second part of this research, we developed BODIPY based near-IR dye as a selective, ratiometric and water-soluble fluorophore for Zn (II) cation. We functionalized the versatile BODIPY from its 3 and 5 positions for long wavelength emission the zinc selective chemosensor.