Onur Akyıldırım

A novel determination of curcumin via Ru@Au nanoparticle decorated nitrogen and sulfur-functionalized reduced graphene oxide nanomaterials

We report the synthesis of Ru@Au nanoparticle involved L-cysteine functionalized reduced graphene oxide (rGO) composites (NSrGO/Ru@AuNPs). The nanocomposites were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The electrochemical determination of curcumin (CR) has been studied using square wave voltammetry (SWV) on a glassy carbon electrode (GCE) modified with NSrGO/Ru@AuNP composites (NSrGO/Ru@AuNPs/GCE). The effective surface areas (ESAs) of the rGO/GCE and NSrGO/Ru@AuNPs/GCE were calculated to be 347 cm2 mg−1 and 1289 cm2 mg−1, respectively. These results show that the electrochemical surface area of the NSrGO/Ru@AuNPs/GCE is 3.71 times higher than that of the rGO/GCE. The developed method was also applied successfully for the determination of CR in plasma and the linearity range of CR was 0.001–0.1 nM with a detection limit of 2.0 × 10−13 M.

Synthesis, In Vitro Antimicrobial and Antioxidant Activities of Some New 4,5-Dihydro-1H-1,2,4-triazol-5-one Derivatives

A series of compounds derived from 4,5‐dihydro‐1H‐1,2,4‐triazol‐5‐one were synthesized and characterized by spectral data. The 12 new compounds were analyzed for their potential in vitro antioxidant activities by three different methods. Compound 4f showed the best activity for the iron binding. In addition, the compounds 4 were titrated potentiometrically with tetrabutylammonium hydroxide in non‐aqueous solvents. The RP‐HPLC capacity factors (k′) of the series were also determined on a C18 column, with methanol/water as the mobile phase. The correlation between log k′ with the percentage of methanol in the mobile phase was used for the determination of the log kw values for these compounds. The antimicrobial activities of these compounds were also screened against bacteria and yeast.

Synthesis and In Vitro Antioxidant Evaluation of New 1,3,5-Tri-{2-methoxy-4-[(4,5-dihydro-1-1,2,4-triazol-5-on-4-yl)-azomethine]-phenoxycarbonyl}-Benzene Derivatives

Nine new 4,5-dihydro-1H-1,2,4-triazol-5-one derivatives were synthesized and characterized by elemental analyses and IR, 1H-NMR, 13C-NMR and UV spectral data. The synthesized compounds were analyzed for their in vitro potential antioxidant activities in three different methods. Those antioxidant activities were compared to standard antioxidants such as BHA, BHT and 𝛼-tocopherol. Compounds 4e, 5a and 5d showed best activity for iron binding. In addition, the compounds 4 were titrated potentiometrically with tetrabutylammonium hydroxide (TBAH) in four non-aqueous solvents (isopropyl alcohol, tert-butyl alcohol, acetone and N,N-dimethyl formamide). Thus, the half-neutralization potential values and the corresponding p𝐾a values were determined in all cases.

2-N-Formilaminotiyofenol Bileşiğinin Spektroskopik Karakterizasyonu, Elektronik ve Çizgisel Olmayan Optik Özellikleri

Bu calismada, 2-N-formilaminotiyofenol bilesiginin teorik spektroskopik ozellikleri incelenerek bazi deneysel verilerle mukayese edilmistir. Bu amacla, oncelikle calisilan bilesik B3LYP, HF yontemleri ve 6-311G++(d,p) temel seti kullanilarak optimize edilmistir. Elde edilen optimize yapi yardimiyla GIAO metoduna gore 1H-NMR ve 13C-NMR kimyasal kayma degerleri Gaussian G09W programi vasitasiyla gaz fazinda hesaplanmistir. δ exp=a+b. δ calc. esitligine gore teorik degerler ile deneysel veriler SigmaPlot programi kullanilarak grafige gecirilmistir. Elde edilen sonuclara gore teorik verilerin deneysel verilerle uyumlu olduklari gorulmustur. Calismanin teorik kisminda ayrica, ayni metodlar ve temel set kullanilarak sentezlenen bilesigin IR frekans degerleri hesaplanmis, bulunan degerler belirli uyum faktorleri ile carpilmistir. Teorik infrared spektrumlari HF ve B3LYP yontemlerine gore elde edilmistir. UV-vis degerleri de etanollu ortamda teorik olarak hesaplanmistir. Ilaveten, molekulun bag uzunluklari, bag acilari, Mulliken atomik yukleri, HOMO-LUMO enerjileri, dipol momentleri, toplam enerjileri, iyonlasma potansiyeli, elektron ilgisi, molekuler yumusaklik, molekuler sertlik ve elektronegatifligi ayni metodlar ve ayni set kullanilarak hesaplanmistir. Son olarak, ilgili bilesigin, cizgisel olmayan optik ozellikleri; tek nokta enerji hesabinda polar hesaplari yapilarak polarizebiliteleri, hiperpolarizebilite degerleri hesaplanmistir.