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    Swallow tail bay-substituted novel perylene bisimides: Synthesis, characterization, photophysical and electrochemical properties and DFT studies
    (Elsevier Science Sa, 2020) Al-Khateeb, Basma; Dinleyici, Meltem; Abourajab, Arwa; Kok, Cansu; Bodapati, Jagadeesh B.; Uzun, Duygu; Koyuncu, Sermet
    Novel, one bay-substituted perylene bisanhydride (6) and two bay-substituted perylene bisimides (7, 10) have been successfully synthesized with a large and swallow tail type, 2-decyl-1-tetradecanoyl substituents at the bay area (1 and 7 positions). The non-bay-substituted perylene bisimides with the same N-substituents were prepared as model compounds (3, 9) for comparison. Absorption and fluorescence, electrochemical, spectro-electrochemical, morphological properties of the compounds were investigated, and then, density functional theory (DFT) simulations were conducted. The compounds 6, 7 and 10 have shown J-aggregated featureless, very broad absorbance through the UV-vis-NIR region with a strong fluorescence quenching attributed to efficient intramolecular electron transfer from electron donor 2-decyl-1-tetradecanoyl substituent to PDI acceptor and scaffolds allow pi-pi intermolecular interactions, induced molecular aggregation. The absolute positions of LUMO and HOMO values for 3, 9, 6, 7 and 10 in solutions were - 3.91/ - 6.09 eV, - 3.93/ - 6.08 eV, -4.02/ - 5.90 eV, - 4.02/- 5.91 eV and - 4.02/ - 5.97 eV, respectively. The onset reduction potential of compounds 6, 7 and 10 are lower than those of compounds 3 and 9. Similarly, the onset oxidation potential values of the compounds 6, 7 and 10 are smaller than those of the non-bay-substituted perylene dyes 3 and 9. The synthesized compounds (3 with 7; 9 with 10) can be exploited as an off-on fluorescence probes for photonic applications.
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    Öğe
    Synthesis, photophysical, electrochemical and morphological properties of a novel cross-linked chitosan-based fluorescent polymer: A fluorescence sensor for single-stranded DNA
    (Pergamon-Elsevier Science Ltd, 2023) Yucekan, Ilke; Dinleyici, Meltem; Temurlu, Selin; Rashid, Rebwar; Bodapati, Jagadeesh B.; Al-Khateeb, Basma; Abourajab, Arwa
    This report details the first-time use of the perylene-3,4,9,10-tetracarboxylic dianhydride as a cross-linker to synthesize a novel fluorescent, chitosan-based cross-linked polymer (3). The polymer has single-stranded DNA (ssDNA) binding properties that can be used in sensor production for detecting salmon sperm DNA. Chitosan polymer's solubility is poor and restricted to only acidic media. In contrast, this new fluorescent chitosan polymer was soluble in various organic solvents and aqueous solutions at different pHs. Its absorption, photo physical, electrochemical and morphological properties were investigated in detail. Gel permeation chromatography determined the weight average molecular mass (Mw) of polymer 3 as 21300 g/mol. Seventeen hydrophobic perylene units were determined in the cross-linked network. The energy levels of the highest occupied molecular orbitals and lowest unoccupied molecular orbitals of the new polymer 3 were calculated as-6.24 and-3.96 eV, corresponding to the band gap of 2.28 eV. Fluorescence and ultraviolet spectroscopy techniques were used to study the interaction between ssDNA and polymer 3. The interaction pointed to the intercalative mode, and the cross-linked chitosan can be used as a stable and sensitive platform for ssDNA detection. These results show a new class of organic biopolymers that could yield promising potential in many biomedical applications.