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    Comparative Study of Enzymatic and Oxidative Polymerization of a Benzothiazole-Based Schiff Base and Its Antibacterial Properties
    (Springer Heidelberg, 2025) Kaya, Ismet; Solmaz, Adnan; Abuawad, Mohammed Majed Shible
    In this study, the Schiff base 1-(((6-nitrobenzo[d]thiazol-2-yl) imino)methyl)naphthalen-2-ol (NBTIMN) was synthesized and subsequently polymerized by two different methods. Oxidative polymerization in the presence of organic (o-(NBTIMN)-O) and aqueous alkaline media (o-(NBTIMN)-A) was one of the techniques. The other was enzyme-catalyzed oxidative polymerization (o-(NBTIMN)-E), which was conducted at room temperature with hydrogen peroxide and the enzyme horse radish peroxidase (HRP). The structures of the obtained oligomers were characterized using FT-IR, 1H-13C-NMR, UV-Vis, CV, and GPC analyses, and their electrochemical and optical band gaps were determined as 2.68, 2.66, and 2.49 eV, and 3.08, 2.90, and 3.07 eV for o-(NBTIMN)-O, o-(NBTIMN)-A, and o-(NBTIMN)-E, respectively. Thermal analyses demonstrated that the o-(NBTIMN)-O and o-(NBTIMN)-A derivatives exhibited enhanced thermal stability, characterized by higher decomposition temperatures and LOI values. SEM analyses revealed distinct differences in surface morphologies depending on the polymerization conditions. Antibacterial assays showed that o-(NBTIMN)-O exhibited the strongest broad-spectrum inhibition, whereas NBTIMN displayed pronounced activity against S. aureus. In contrast, o-(NBTIMN)-A and o-(NBTIMN)-E were found to be inactive. These results highlight the critical influence of polymerization conditions on both the physicochemical characteristics and the biological activities of the synthesized structures. Importantly, the comparative design of enzymatic and chemical polymerization demonstrates the potential for environmentally friendly synthesis strategies. The distinct electrochemical and thermal properties suggest applicability in electronics and sensor-related fields, while the pronounced antibacterial activity of o-(NBTIMN)-O holds promise for biomedical and antimicrobial applications.
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    High thermal stability and dielectric performance of phenylhydrazine-based Schiff base oligomers obtained via oxidative polycondensation
    (Springer, 2025) Solmaz, Adnan; Kaya, Ismet; Bayir, Erdal
    In this study, the 2-PHMBD Schiff base, synthesized through the condensation of 2,4-dihydroxybenzaldehyde (2,4-DHBA) with phenylhydrazine (PH), was subjected to oxidative polymerization in a basic medium using hydrogen peroxide (H2O2), sodium hypochlorite (NaOCl), and molecular oxygen (O2) as oxidizing agents. Three oligomers, designated as o-(2-PHMBD)-P, o-(2-PHMBD)-H, and o-(2-PHMBD)-O, were successfully obtained and comprehensively characterized by FT-IR, 1H-13C-NMR, UV-Vis, CV, GPC, SEM, TGA, and DSC analyses. Spectroscopic results confirmed the successful polymerization, while morphological and thermal analyses revealed the distinct physical characteristics of the oligomers. According to GPC data, o-(2-PHMBD)-H exhibited the highest average molecular weight of 4700 Da, and TGA analysis demonstrated that o-(2-PHMBD)-O had the highest thermal stability with a residue of 46% at 1000 degrees C. The DSC results showed the highest glass transition temperature of 132 degrees C for o-(2-PHMBD)-H. UV-Vis and CV measurements indicated reduced optical and electrochemical band gaps compared with the monomer, with the lowest optical band gap determined as 2.74 eV. Dielectric measurements revealed that o-(2-PHMBD)-H displayed the highest dielectric constant of 2.57 and conductivity of 2.49 x 10(-)7 S cm(-)1. These results demonstrate that phenylhydrazine-based Schiff base oligomers possess high thermal stability and favorable dielectric properties, making them promising materials for optoelectronic and dielectric device applications.
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    Öğe
    Synthesis and characterization of oligomers contain phenylhydrazyne unit via oxidative polycondensation: Adsorption studies, kinetic modeling and validation methods
    (Elsevier, 2025) Bayir, Erdal; Solmaz, Adnan; Kaya, Ismet; Yagmur, Hatice Karaer
    In this study, 4-((2-phenylhydrazono)methyl)benzene-1,2-diol (4-PHBD) Schiff base was obtained from the condensation reaction between 3,4-dihydroxybenzaldehyde (3,4-DHBA) and phenylhydrazine (PH). The obtained Schiff base (4-PHBD) was polymerized using H2O2, NaOCl, and O2 oxidants in an aqueous basic medium (10 % KOH) and 4-PHBD was converted to o-(4-PHBD)-P (by H2O2 oxidant), o-(4-PHBD)-H (by NaOCl oxidant) and o-(4-PHBD)-O (by O2 oxidant). The structures of Schiff base and oligomers were characterized with FT-IR, NMR, SEM, TGA, UV-Vis, CV and GPC measurements. The Cyclic Voltammetry and UV-Vis measurements were used to ascertain the compounds' optical (Eg) and electrochemical (Eg') band gaps, respectively. The Eg values of o-(4-PHBD)-P, o-(4-PHBD)-O and o-(4-PHBD)-H were found be 2.99, 2.63 and 3.26 eV, respectively. o-(4-PHBD)-O was used as an adsorbent in the removal of methylene green (MG) from an aqueous solution. The obtained data were applied to pseudo-first order and pseudo-second order kinetic models. It was determined that the adsorption process obeyed the pseudo first order kinetic model. The kinetic model was validated with R2, RMSE, SSE, SD, Delta qe (%), MSE and ARE validation methods. The activation energy (Ea) was calculated as 7.31 kJ mol-1 using the Arrhenius equation. It was determined that the adsorption of MG on o-(4-PHBD)-O was physical adsorption.
  • Küçük Resim
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    Synthesis, characterization and thermal properties of chalcone methacrylamide polymers containing methoxy group in side chain
    (Springer, 2021) Solmaz, Adnan; İlter, Zülfiye; Kaya, İsmet
    In this study, thermal and dielectric properties of chalcone methacrylamide polymers containing methoxy group in side chain were studied. At first the chalcone compounds abbreviated as CHAL1, CHAL2, and CHAL3 containing the methoxy group in the side chain were synthesized. Then, the monomers abbreviated as M1, M2 and M3 were synthesized by the reaction of chalcone compounds with methacryloylchloride. The chalcone methacrylamide polymers abbreviated as P1, P2 and P3 were prepared via the free radical polymerization at 70 C-o in DMF solution. The structures of synthesized chalcone compounds were characterized by FT-IR, UV-Vis, H-1 and (13) C-NMR. Thermal behavior of polymers was investigated with DSC and TGA measurements. The glass transition temperatures (T-g) of P1, P2 and P3 were found at 85, 95 and 140 C-o, respectively, from DSC measurements. According to the Flynn-Wall-Ozawa (FWO) method, the average decomposition activation energy of the P2 was calculated to be 113.60 kJ mol(- 1) by TGA curves at different heating rates such as 5, 10, 15 and 20 C-o min(- 1). For investigating the dielectric properties of polymers, dielectric constant (epsilon'), dielectric loss factor (epsilon"), and ac conductivity values were measured using an impedance analyzer in the frequency range of 100 Hz-10 kHz frequencies. The results were plotted as a function of frequency. The conductivity values of P1, P2 and P3 were found to be 1.74, 2.24 and 2.63 x 10(- 9) S cm(- 1), respectively. The surface morphologies of the polymers were examined by SEM. The optical properties of polymers were examined by UV-Vis. The biological activities of polymers were determined by disk diffusion method. Polymers have exhibited good antimicrobial property against Staphylococcus aureus, Klebsiella pneumonia and have exhibited good antifungal property against Candida albicans.
  • Küçük Resim
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    Synthesis, characterization, thermal and kinetic properties of chalcone methacrylamide polymers containing halogen group in side chain
    (Springer Science and Business Media Deutschland GmbH, 2022) Solmaz, Adnan; İlter, Zülfiye; Kaya, İsmet
    Abstract: In this study, first the chalcone compounds abbreviated as CHAL-F, CHAL-Cl and CHAL-Br containing the halogen group in the side chain were synthesized in medium alkaline at 0 °C. Then, chalcone methacrylamide monomers abbreviated as M-F, M-Cl and M-Br containing halogen group in side chain were synthesized by the reaction of the chalcone compounds with methacryloylchloride at 0–5 °C in the presence of triethylamine (E3N). The chalcone methacrylamide polymers abbreviated as P-F, P-Cl and P-Br were prepared by the free radical polymerization at 70 °C, in DMF solution and by 2,2ʹ-azobisizobutyronitrile (AIBN) initiator. The structures of synthesized compounds were characterized by FTIR, UV–Vis and 1H-13C-NMR. Thermal characterizations of polymers were performed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The glass transition temperature (Tg) of P-F, P-Cl and P-Br was found at 103, 129 and 110 °C, respectively, from DSC measurements. According to the Flynn–Wall–Ozawa (FWO) method, the average decomposition activation energy of the P-Br was found as 76.84 kJ mol−1 from the TGA thermograms at different heating rates such as 10, 15 and 20 °C min−1. The contribution of the polar functional groups carried by the synthesized chalcone methacrylamide polymers to some dielectric behavior was examined through the impedance analyzer as a function of frequency. The conductivity values of P-F, P-Cl and P-Br were found 2.00 × 10–9, 2.04 × 10–9 and 1.91 × 10–9 S cm−1, respectively. The SEM images were used to investigate the morphologies of polymers. The surface morphologies and molecular weight distributions of the polymers were imaged by scanning electron microscopy (SEM) and gel permeation chromatography (GPC), respectively. The optical properties of polymers were investigated by UV–Vis and their antimicrobial activities determined by disk diffusion method. The polymers have exhibited good antimicrobial property against Staphylococcus aureus, Klebsiella pneumonia and have exhibited good antifungal property against Candida albicans.
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    Synthesis, Characterization, Thermal Behavior, and Dielectric Properties of Methacrylate Polymers Containing Imine Bonding
    (Springer, 2021) Solmaz, Adnan; İlter, Zülfiye; Kaya, İsmet
    Two diferent Schif bases, viz. 1-{4-[(5-bromo-2-hydroxybenzyliden)amino]phenyl}ethanone (5-Br-2HBAPE) and 1-{4-[(4-hydroxybenzylidene)amino]phenyl}ethanone (4-HBAPE), have been prepared by condensation of 5-bromosalicylaldehyde and 4-hydroxybenzaldehyde with 4-aminoacetophenone in ethanol at molar ratio of 1:1. Then, Schif base methacrylate monomers, i.e., 2-(((4-acetylphenyl)imino)methyl)-4-bromophenylmethacrylate (APIMBPM) and 2-(((4-acetylphenyl)imino)methyl)phenylmethacrylate (APIMPM), were synthesized by reaction of each Schif base compound with methacryloylchloride at 0°C to 5°C. Schif base methacrylate polymers poly(APIMBPM) and poly(APIMPM) were then prepared by free-radical polymerization in tetrahydrofuran (THF) at 70°C using azobisisobutyronitrile (AIBN) as initiator. The structure of 5-Br-2HBAPE, 4-HBAPE, APIMBPM, APIMPM, poly(APIMBPM), and poly(APIMPM) was confrmed by Fourier-transform infrared (FT-IR) and 1 H and 13C nuclear magnetic resonance (NMR) spectroscopy. The thermal behavior of poly(APIMBPM) and poly(APIMPM) was studied by diferential scanning calorimetry (DSC) and thermogravimetry (TG). The glass-transition temperature (Tg) of poly(APIMBPM) and poly(APIMPM) was found to be 113°C and 108°C, respectively. The residual amount of poly(APIMBPM) and poly(APIMPM) at 1000°C was found to be 45.60% and 26.35%, respectively. Dielectric and conductivity measurements were carried out on the Schif base methacrylate polymers by impedance analysis as a function of frequency. The conductivity of poly(APIMBPM) and poly(APIMPM) was found to be 1.30 × 10−9 S cm−1 and 2.14 × 10−9 S cm−1, respectively. Scanning electron microscopy (SEM) was used to investigate the morphology of the Schif base methacrylate polymers, and their antimicrobial activity against bacteria and fungus was determined by disk difusion method. Poly(APIMBPM) exhibited good antibacterial property against Klebsiella pneumonia. Poly(APIMBPM) and poly(APIMPM) exhibited good antifungal action against Candida albicans. We thus describe the synthesis of diferent Schif base methacrylate polymers and their thermal behavior, electrical properties, and antimicrobial activities.