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Amino-functionalized nitrogen-doped graphene quantum dots and silver-graphene based nanocomposites: Ultrafast charge transfer and a proof-of-concept study for bioimaging applications
(Elsevier B.V., 2022) Karatay, Ahmet; Erdener, Diğdem; Gürcan, Cansu; Yıldız, Elif Akhüseyin; Yılmazer, Açelya; Boyacıoğlu, Bahadır; Yıldız, Mustafa
Recent advances in nanotechnology have led to the use of graphene quantum dots (GQDs) for functional imaging and cancer therapy. Thanks to the physicochemical properties of graphene, GQDs have been functionalized and modified to improve their biological properties. In this study, polyethyleneimine functionalized nitrogen-doped graphene quantum dots (PEI N-doped GQDs) and silver nanoparticles/nitrogen-doped graphene quantum dots (AgNPs/PEI N-doped GQDs) nanocomposites have been developed. The PEI N-doped GQDs show a strong emission spectrum at maximum 446 nm with 356 nm excitation wavelength while AgNPs/PEI N-doped GQDs nanocomposites indicate weak fluorescence intensity at maximum 446 nm with 344 nm excitation wavelength. Based on the femtosecond transient absorption spectroscopy measurements, this emission quenching can be attributed that the excited state lifetime of PEI N-doped GQDs decreasing in the presence of AgNPs due to ultrafast electron transfer from PEI N-doped GQDs to AgNPs. It is also supported by theoretical results sensing ability of AgNPs/PEI N-doped GQDs nanocomposite is better than that of PEI N-doped GQDs. When lung adenocarcinoma cells (A549) were treated with GQDs, material-specific fluorescent signals were obtained from the cytoplasm of cells only treated with Ag/PEI N-doped GQDs, as compared with N-doped GQDs. Overall, this study shows that Ag/PEI N-doped GQDs are promising nanosystems for bioimaging applications.
Anilino ve fenoksi fosfazen türevlerinin sentezi, yapılarının spektroskopik yöntemlerle incelenmesi
(Çanakkale Onsekiz Mart Üniversitesi, 2011) Erdener, Diğdem; Yıldız, Mustafa
Bu çalışmada halkalı fosfazenler trimer ve tetramerin aromatik aminler ve fenoller ile reaksiyonları incelendi. Anilino reaksiyonları için aminopodand 5, 6, 7 ve 8 sentezlenerek, ticari dianilinler satın alınarak kullanıldı. Amino podandlar ile trimerin reaksiyonundan spiro 9, 10 ve ansa 11 bileşikleri, tetramerin reaksiyonundan spiro 12 fosfazen bileşiği elde edildi. Ticari dianilinler ile trimerin reaksiyonundan bino bileşikleri 13, 14 ve 15 sentezlendi. Trimerin bisfenol ile reaksiyonundan mono-spiro fenoksifosfazen 16 ve di-spiro fenoksifosfazen 17 bileşiği, tetramerin reaksiyonundan mono-spiro fenoksifosfazen 18 bileşiği hazırlandı. Bileşik 16 ve 17'nin aminopodand 6 ile reaksiyonundan bino 19 ve spiro 20 bileşiği elde edildi. Bileşik 17' nin aminopodand 5 ve bisfenol ile reaksiyonundan spiro 21 ve 22 bileşikleri sentezlendi.Sentezlenen fosfazen bileşiklerinin yapıları, element analizi, MS, IR, 1H-NMR, 13C-NMR ve 31P-NMR spektroskopik yöntemleri ile aydınlatıldı.
Chromogenic sensing, biological, and optical properties of Schiff bases of 2-amino-6-methoxybenzothiazole
(Elsevier B.V., 2024) Akhüseyin Yıldız, Elif; Pepe, Yasemin; Erdener, Diğdem; Karatay, Ahmet; Boyacıoğlu, Bahadır; Ünver, Hüseyin; Yapar, Gönül; Demir, Neslihan; Yıldız, Mustafa
In this study, a new series of Schiff base benzothiazole derivatives were synthesized and their structures were characterized by elemental analysis, FTIR, UV–VIS and NMR spectroscopy. The biological, sensory and photophysical properties of the benzothiazole derivatives were investigated. The sensing properties of the compounds were investigated UV–VIS spectroscopically, calorimetrically and theoretically. All compounds showed colorimetric, fluorometric and spectroscopic sensor properties for F−, CN−, AcO−, H2PO4− and OH− anions. Furthermore, DNA binding, DNA cleavage and antioxidant activities of compounds 1-4 were investigated. All compounds affected pBR322 DNA both hydrolytically and oxidatively, interacted with DNA in electrostatic mode, and also compounds 1 and 2 exhibited antioxidant activity close to standard BHT. In addition, the effects of electron donating and accepting substituents on the emission properties and charge transfer dynamics were investigated by fluorescence and femtosecond transient absorption spectroscopy measurements, respectively. According to fluorescence measurements, compounds 3 and 4 showed emission signal, while compounds 1 and 2 showed fluorescence quenching and weaker emission signal.
Effect of group electronegativity on spectroscopic, biological, chromogenic sensing and optical properties of 2-formyl-benzene sulfonic acid sodium salt-based Schiff bases
(Elsevier B.V., 2023) Akhüseyin Yıldız, Elif; Pepe, Yasemin; Erdener, Diğdem; Karatay, Ahmet; Boyacıoğlu, Bahadır; Ünver, Hüseyin; Yapar, Gönül; Demir, Neslihan; Yıldız, Mustafa; Elmalı, Ayhan
In this study, 2-formylbenzenesulfonic acid sodium salt-based Schiff bases were synthesized from the reactions of 2-formylbenzenesulfonic acid sodium salt with 2-amino-4-chlorophenol and 2-amino-4-methylphenol. The structure of the compounds was determined by FTIR, UV–Vis and NMR spectroscopy methods using both experimental and DFT methods. The anion sensor properties of the compounds were investigated both UV–Vis spectroscopically and calorimetrically. In addition, the antimicrobial activities, interactions with DNA, DNA cleavage and antioxidant activities of Schiff bases were investigated. Additionally, the effects of group electronegativity on the spectroscopic, biological, chromogenic sensing and optical properties of chlorine and methyl side groups and sodium 2-sulfobenzalidene-aminophenol-based Schiff bases were investigated.
Sübstitüe halkalı fosfazenlerin sentezi ve yapılarının spektroskopik yöntemlerle incelenmesi
(Çanakkale Onsekiz Mart Üniversitesi, 2006) Erdener, Diğdem; Yıldız, Mustafa
SÜBSTİTÜE HALKALI FOSFAZENLERİN SENTEZİ VE YAPILARININSPEKTROSKOPİK YÖNTEMLERLE İNCELENMESİÖZETBu çalışmada 2,2'-metilenbis(4-klorofenol)'un sodyum tuzu ile hekzaklorosiklotrifosfazenTHF ortamında etkileştirildi. Di sübstitüe fenoksi fosfazen (2, 3) bileşikleri sentezlendi. Fenoksifosfazen (2, 3) ile ter-butil aminin aşırısının THF ortamındaki reaksiyonundan geminal-di(ter-butilamino)fenoksi fosfazen (4, 5) bileşikleri elde edildi.Sentezlenen fosfazen bileşiklerinin yapıları, element analizi, IR, 1H-, 13C-, 31P-NMR ve MSspektroskopik verilerinden faydalanılarak aydınlatıldı. Ayrıca bileşik 2' nin yapısı X-ışınlarıkristallografisi metoduyla aydınlatıldı.Anahtar sözcükler : Hekzaklorosiklotrifosfazen, Fenoksi Fosfazen, Geminal fosfazen,Spektroskopi, X-ışınları kristallografisi
Synthesis and characterization of a highly selective turn-on fluorescent chemosensor for Sn2+ derived from diimine Schiff base
(Elsevier, 2021) Kolcu, Feyza; Erdener, Diğdem; Kaya, İsmet
This study is exploratory in proposing a Schiff base (Ligand=L), which was designed and synthesized through one-step condensation reaction using 2,2 '-bithiophene-5-carboxaldehyde and 4,4'-diaminotriphenylamine (DATPA), was employed for fluorescent detection of the presence of Sn2+ ions. The ligand was well-characterized by infrared (FT-IR), UV-vis spectroscopy, H-1 and C-13 nuclear magnetic resonance (NMR) analyses. The chelation of the ligand with Sn2+ ion caused a decrease in the optical band gap in the UV-vis absorption spectrum of the ligand upon the addition of Sn2+ ions. The binding of L to Sn2+ caused a blue shift due to an internal charge transfer (ICT). The synthesized L was conceivable to be an outstanding receptor to detect Sn2+ ions with a remarkable fluorescent enhancement due to a potent chelation enhanced fluorescence (CHEF) effect. Non fluorescent ligand executed a fast response and highly sensitive turn-on fluorescent sensing behavior to detect Sn2+ ions via 1:2 (ligand:metal) complexation without any interference from other metal cations. The ligand's specificity was indicated with an observation of no transition in colour with any other metal cations. The selectivity of the probe for Sn2+ was confirmed by the absence of any interference from other competitive cationic species. The calculated limit of detection (LOD) and binding constant (K-a) were found to be 3.14 x 10(-7) M and 6.8 x 10(9) M-2, respectively. The synthesized ligand was of use for the devise of metal sensors based on diimine Schiff base.
Synthesis of a cationic ruthenium(ii) complex and its non-enzymatic glucose-sensing properties
(Royal Society of Chemistry, 2023) Dayan, Serkan; Özdemir, Namık; Erdener, Diğdem; Dayan, Osman; Çetinkaya, Bekir
The new cationic ruthenium(ii) complex (2) was synthesized via the reaction of N,N′-[1,1′-(pyridine-2,6-diyl)bis(ethan-1-yl-1-ylidene)]bis(2-ethyl-6-methylaniline) and [RuCl2(p-cymene)]2, and it was fully characterized using NMR, FT-IR, single-crystal X-ray diffraction, ESI-MS, UV-vis, CV and thermal analysis methods; theoretical computational characterizations and geometric parameters for 2 were also carried out via quantum chemical calculations using the density functional theory (DFT) method. In addition, the synthesized Ru(ii) complex (2) was immobilized on fabricated RGO-TiO2@FTO to evaluate its non-enzymatic biosensing properties, and the sensing properties of the resulting Ru(ii)-RGO-TiO2@FTO electrode were recorded. As a glucose-sensing model, at an applied potential of +0.34 V, the Ru(ii)-RGO-TiO2@FTO electrode presented a moderately good sensitivity of 62.69 μA mM−1 cm−1. Various modifications of Ru(ii)-RGO-TiO2@FTO-type electrodes, such as the metal complex, and material types and ratios, will enable the design of future biosensor devices with improved performance.
Synthesis of pyrene and pyrrole-appended fluorescent turn-off sensor toward Cr(VI) detection: Chemical oxidative and electrochemical polymerization of carboxamide
(Elsevier B.V., 2024) Kaya, İsmet; Karacan Yeldir, Elif; Kolcu, Feyza; Erdener, Diğdem
A carboxylic amide compound containing pyrrole and pyrene groups, referred to as PP, was synthesized and characterized for its structural, optical, and electrochemical properties. Upon excitation with 320 nm light, PP displayed blue emission at 387 nm, which was found to be quenched due to chelate formation in the presence of Cr(VI). Conducted competition experiments involving chloride salts of Ag+, Al3+, Cd2+, Co2+, Cr3+, Fe3+, Hg2+, K+, Mn2+, Ni2+, Pb2+, Sn2+, and Zn2+ demonstrated the notable selectivity of compound PP towards Cr(VI) ions. This selectivity was evidenced by a pronounced turn-off fluorescent effect, attributed to a chelation-enhanced quenching (CHEQ) mechanism by the formation of 1:2 chelation between Cr(VI) and the ligand PP. Moreover, addition of EDTA to PP– Cr(VI) chelation recovered the fluorescence offering receptor PP as a reversible sensor. The PP probe demonstrated remarkable selectivity in detection Cr(VI) ions among various metallic ions, displaying a limit of detection (LOD) value of 0.106 µM. Chemical oxidative and electropolymerization methods were employed to synthesize two distinct polymers, namely Poly(PP)-O and Poly(PP)-E, respectively. The electropolymerization of PP was carried out in 0.1 M TBAF6P serving as a supporting electrolyte solution, while oxidative polymerization was conducted in the presence of FeCl3. Mass average molecular weight of the oxidative polymerization product was 5200 Da, as determined by GPC analysis. Thermal characterization was performed via TG-DTA-DTG curves. The electropolymerization product of PP coated on the ITO surface was further characterized by SEM.
Synthesis, characterization, and optimum reaction conditions of oligo-2-[(pyridine-2-yl-methylene) amino] phenol
(John Wiley & Sons Inc, 2004) Kaya, İsmet; Moral, Fatma; Erdener, Diğdem
The reaction conditions of the oxidative polycondensation of 2-[(pyridine2-yl-methylene) amino] phenol (2-PMAP) with air O-2, H2O2, and NaOCl were studied in an aqueous alkaline medium between 60 and 90 degreesC. Oligo-2-[(pyridine-2-yl-methylene) amino] phenol (O-2-PMAP) was characterized with H-1 NMR, Fourier transform infrared, ultraviolet-visible, size exclusion chromatography (SEC), and elemental analysis techniques. Moreover, solubility testing of the oligomer was performed in polar and nonpolar organic solvents. With the NaOCl, H2O2, and air O-2 oxidants, the conversions of 2-PMAP into O-2-PMAP were 98, 87, and 62%, respectively, in an aqueous alkaline medium. According to SEC, the number-average molecular weight, weight-average molecular weight, and polydispersity index of O-2-PMAP were 2262 g mol(-1), 2809 g mol(-1), and 1.24 with NaOCl, 3045 g mol(-1), 3861 g mol(-1), and 1.27 with air O-2, and 1427 g mol(-1), 1648 g mol(-1), and 1.16 with air H2O2, respectively. Also, thermogravimetric analysis showed that O-2-PMAP was stable against thermooxidative decomposition. The weight loss of O-2-PMAP was 96.68% at 900 degreesC. (C) 2004 Wiley Periodicals, Inc.

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