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    Conjugated diazochalcone-phosphazene hybrids: Design, synthesis, and substituent effects on optical and electrical properties
    (Elsevier, 2026) Aydin, Derya; Cetiner, Rumeysa; Caliskan, Eray; Aslan, Fehmi; Biryan, Fatih; Koran, Kenan
    Phosphazene derivatives have gained an important place in functional materials chemistry thanks to their versatile structural regularity and chemical stability, while diazochalcone structures are compounds with remarkable potential in organic electronic and photonic applications as photosensitive conjugated systems. In this study, two new hybrid structures, CRG-4F and CRG-4DMA, functionalized with a dual diazochalcone group on the cyclotriphosphazene core, obtained by combining these two important structures, were synthesized, characterized, and their optoelectronic properties were studied in detail. In the optical investigations by UV-Vis spectroscopy, the maximum absorption wavelength of CRG-4F was determined as similar to 350 nm, and that of CRG-4DMA as similar to 405 nm due to the broadening of the conjugation. The direct band gaps calculated by the Tauc method are 2.95 eV and 2.62 eV, respectively, revealing the band gap narrowing effect of the electron-donating dimethylamino group. Both compounds were tested in a diode configuration in Al/organic material/p-Si configuration and exhibited forward conduction and reverse low current characteristics. CRG-4F exhibited superior diode behavior with a higher rectification ratio, while CRG-4DMA stood out as a photosensitive compound by generating more pronounced photoresponse with increasing light intensity under reverse voltage. The results show that the combination of phosphazene core with diazochalcone offers an effective design strategy to develop a new generation of organic-inorganic semiconductors with tunable band gap, solvent-sensitive optical properties, and functional diode performance depending on the nature of the substituent. The findings highlight the potential of these materials in opto-electronic devices, especially in visible region sensitive photodetectors, organic light emitting components, and sensor technologies.
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    Synthesis of New Cinnamoyl-Amino Acid Conjugates and in Vitro Cytotoxicity and Genotoxicity Studies
    (Wiley-V C H Verlag Gmbh, 2022) Caliskan, Eray; Ozturk, Dilara Altay; Koran, Kenan; Tekin, Suat; Sandal, Suleyman; Erkan, Sultan; Gorgulu, Ahmet Orhan
    Amino acid conjugates are described by the reaction of amino acids with bioactive organic groups such as vitamins, hormones, flavonoids, steroids, and sugars. In this study, 12 new conjugates were synthesized by reaction of cinnamic acid derivatives with various amino acids. Cytotoxic studies against four different human cancer cells (MCF7, PC-3, Caco-2, and A2780) were carried out by MTT assay method at five different concentrations. The structure-activity relationships based on the cell viability rates were evaluated. To compare the anticancer activities of the compounds using computational chemistry methods, they were docked against A2780 human ovarian cancer, Michigan Cancer Foundation-7 (MCF7), human prostate cancer (PC-3) and human colon epidermal adenocarcinoma (Caco-2) cell lines and compared with the standard 5-Fluorouracil. The results indicate that the efficacy of cinnamic acid derivatives increases with the presence of amino acids. Comet assay was conducted to understand whether the cell deaths occur through DNA damage mechanism and the results exhibit that the changes in the specified parameters were statistically significant (p<0.05). Our study demonstrated that the compounds cause cell death through the formation of DNA damage mechanism.
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    The first peptide derivatives of dioxybiphenyl-bridged spiro cyclotriphosphazenes: In vitro cytotoxicity activities and DNA damage studies
    (Academic Press Inc Elsevier Science, 2023) Koran, Kenan; Caliskan, Eray; Ozturk, Dilara Altay; Capan, Irfan; Tekin, Suat; Sandal, Suleyman; Gorgulu, Ahmet Orhan
    In this study, we aimed to synthesize new peptide-substituted cyclotriphosphazenes from a series of tyrosine -based peptides and dioxyphenyl-substituted spirocyclotriphosphazenes, and to evaluate their in vitro cytotox-icity and genotoxicity activities. Genotoxicity studies were conducted to understand whether the cytotoxic compounds cause cell death through DNA damage. The structures of the novel series of phosphazenes were characterized by FT-IR, elemental analysis, MS, 1D (31P, 1H, and 13C-APT NMR), and 2D (HETCOR) NMR spectroscopic techniques. In vitro cytotoxic activities were carried out against human breast (MCF-7), ovarian (A2780), prostate (PC-3), colon (Caco-2) cancer cell lines and human normal epithelial cell line (MCF-10A) at different concentrations by using an MTT assay. The compounds showed considerable reductions in cell viability against all human cancer cell lines. Especially, the compounds exhibited notable effects in A2780 cell lines (p < 0.05). The IC50 values of the compounds in the A2780 cell line were calculated to be 1.914 mu M for TG, 20.21 mu M for TV, 20.45 mu M for TA, 4.643 mu M for TP, 5.615 mu M for BTG, 1.047 mu M for BTV, 27.02 mu M for BTA, 0.7734 mu M for BTP, 21.5 mu M for DTG, 1.65 mu M for DTV, 2.89 mu M for DTA and 4.599 mu M for DTP. DNA damage studies of the compounds were conducted by the comet assay method using tail length, tail density, olive tail moment, head length, and head density parameters, and the results showed that the cell death occurred through DNA damage mechanism. In a nutshell, these compounds show promising cytotoxic effects and can be considered powerful candidate molecules for pharmaceutical applications.