Dilek Şenol

Synthesis and characterization of polyphenol derived from Schiff bases containing methyl and carboxyl groups in the structure

In this study, a series of Schiff bases (CBAA4MP, CBAA5MP, and CBAA3MP) which differ from each other based on the position of methyl group were synthesized. The derived monomers were changed into their polymer kind (P-CBAA4MP, P-CBAA5MP, and P-CBAA3MP) by oxidative polycondensation in aqueous alkaline medium using NaOCl as the oxidant. The structures of the synthesized compounds were enlightened using FT-IR, UV–vis, 1H-NMR, and 13C-NMR analyses. The 1H-NMR and 13C-NMR results showed that polymerization preceded by C–C and C–O–C couplings of the monomer units (phenylene and oxyphenylene groups). The molecular weight dispersion of the polymers was designated by size exclusion chromatography analysis. Electrochemical () and optical (Eg) band gaps of the synthesized substances are measured using CV and UV–vis techniques, in order of. Solid state electrical conductivities of both doped and undoped states of the synthesized polymers were evaluated. Also, the effects to the electrochemical band gaps values of ortho, meta, and para positions of methyl group in the structures of polymers were examined from CV measurements.

SYNTHESIS, CHARACTERIZATION AND ANTIMICROBIAL PROPERTIES OF 4-[(4-HYDROXYBENZYLIDENE) AMINO] PHENOL AND ITS POLYMER

The oxidative polycondensation reaction conditions of 4-[(4-hydroxybenzylidene) amino] phenol (4-HBAP) were studied with H2O2, air oxygen and NaOCl in an aqueous alkaline medium between 50 and 90°C. The structures of the obtained monomer and polymer were confirmed by FT-IR, UV-Vis, 1H- and 13C-NMR and elemental analysis. The characterization was made by TG-DTA, size exclusion chromatography (SEC) and solubility tests. At the optimum reaction conditions, the yield of poly[4-(4-hydroxybenzylidene amino) phenol] (P-4-HBAP) was found to be 48.3% (for H2O2 oxidant), 80.5% (for air O2 oxidant) and 86.4% (for NaOCl oxidant). According to the SEC analysis, the number-average molecular weight (Mn), weight-average molecular weight (Mw) and polydispersity index (PDI) values of P-4-HBAP was found to be 8950, 10970 g mol-1 and 1.225, respectively, using H2O2; and 11610, 15190 g mol-1 and 1.308 respectively, using air O2 and 7900, 9610 g mol-1 and 1.216, respectively, using NaOCl. According to TG-DTA analyses, P-4-HBAP was more stable than 4-HBAP against thermal decomposition. The weight loss of P-4-HBAP was found to be 49.27% at 1000°C. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) values calculated from electrochemical measurement. Electrochemical energy gaps (Eg′) of 4-HBAP and P-4-HBAP were found to be -5.46, -5.28; -2.26, -2.67; 3.20 and 2.61 eV, respectively. According to UV-Vis measurements, optical band gap (Eg) of 4-HBAP and P-4-HBAP were found to be 3.34 and 3.01 eV, respectively. Also, antimicrobial activities of 4-HBAP and P-4-HBAP were examined against selected some bacteria. The electrical conductivity of the polymer was measured after doping with iodine.

Synthesis and Characterization of Oligo-Salicylidene-3-Amino-1, 2, 4-Triazole and Oligo-2-Hydroxy Naphthalidene-3-Amino-1, 2, 4-Triazole

Abstract: In this study, the oxidative polycondensation reaction conditions of oligo-salicylidene-3-amino-1, 2, 4-triazole (OSAT) and oligo-2-hydroxy naphthalidene-3-amino-1, 2, 4-triazole (OHNAT) with air O2, H2O2, and NaOCl were studied in an aqueous alkaline medium at 80°C. The oligo-salicylidene-3-amino-1, 2, 4-triazole and oligo-2-hydroxy naphthalidene-3-amino-1, 2, 4-triazole were characterized by 1H-nuclear magnetic resonance (NMR), Fourier transform-infrared (FT-IR), ultraviolet-visible spectrometry (UV-Vis), size exclusion chromatography (SEC), and elemental analysis techniques. According to the SEC analysis, the number average–molecular weight (Mn), weight average–molecular weight (Mw), and polydispersity index (PDI) values of OSAT and OHNAT were found to be 1980 g mol−1, 5115 g mol−1, and 2.58 and 1752 g mol−1, 4300 g mol−1, and 2.45, respectively. Also, thermogravimetric (TG) analyses were shown to be unstable for oligo-salicylidene-3-amino-1, 2, 4-triazole and oligo-2-hydroxy naphthalidene-3-amino-1, 2, 4-triazole against thermo-oxidative decomposition. The weight losses of OSAT and OHNAT were found to be 97.30% and 98.48% at 900°C, respectively.

Investigation of Thermodynamic Properties of PIBMA-PVC (50%/50%) and P-4-t-BS-PVC (50%/50%) Blends Systems by Inverse Gas Chromatography

ABSTRACT The specific retention volumes, , values of the poly (isobutyl methacrylate)-poly (vinyl chloride) (PIBMA-PVC) (50%/50%) and poly (-4-tert-butyl styrene)-poly (vinyl chloride) (P-4-t-BS-PVC) (50%/50%) blends-probe systems were calculated between 383 and 423 K by inverse gas chromatography technique. According to these data, the thermodynamic properties such as the sorption enthalpy ( ), sorption free energy ( ), sorption entropy ( ), the partial molar free energy ( ), and the partial molar heat of mixing, ( ) at infinite dilution were determined for the interactions of (PIBMA-PVC) (50%/50%) and (P-4-t-BS-PVC) (50%/50%) blends with alcohols and aromatics and CHCl3 by inverse gas chromatography method in the temperature range of 383–423 K. The sorption values and values were observed to be exothermic, and , , and values were observed to be endothermic. The values of PIBMA-PVC (50%/50%) and P (-4-t-BS)-PVC (50%/50%) blends-alcohols systems changed from 9.73 to 18.17 kJ/mol and from 10.00 to 16.83 kJ/mol, respectively. Flory-Huggins interaction parameters, χ12, χ13, χ14, χ1(23) and χ1(24) values of PVC, PIBMA, P (4-t-BS), PIBMA-PVC (50%/50%) and P (-4-t-BS)-PVC (50%/50%) blend systems were determined at 413–423 K. In addition, χ23′ and χ24′ values of alcohols changed from 1.191 to 2.473 and from 1.342 to 1.839 for PIBMA-PVC (50%/50%) and P (-4-t-BS)-PVC (50%/50%) blends, respectively, at 413 K.

Study of Changes in Polymer–Probe Interactions with Stabilization Temperature of a Column Contained Polyacrylonitrile by Using Inverse Gas Chromatography

Abstract A column filled with chromosorb W (45–60 mesh) coated with poly-acrylonitrile (PAN) was conditioned at different temperature, 150, 175, 200, 225, 260, and 275°C under nitrogen current. After each stabilization the specific retention volumes, , of probes were determined by using inverse gas chromatography (IGC) techniques for acetone, acetonitrile, p-xylene, n-propanol, pyridine, and n-hexane as probes in the temperature range 50–150°C. When temperature changed from 150 to 275°C specific retention volumes, , and values of probes were increased. Also, values of polar probes were higher than those of unpolar probes. A film of PAN homopolymer was heated in an oven at 150, 175, 200, 225, 260, and 275°C under nitrogen current (the conditions are the same as those of coated PAN in the column). After each heating event, PAN films were used for Fourier transform infrared spectroscopy (FT-IR) measurements. The FT-IR spectra of PAN film (when temperature increased from 150 to 275°C), showed some new peaks at the 740–3350 cm−1 region and increased intensity of some peaks between 2900–3500 cm−1 and 1100–1700 cm−1. According to differential scanning calorimeter (DSC) analysis, the glass transition temperature of PAN found to be 130°C.

Synthesis, Characterization, Electrical Conductivity and Fluorescence Properties of Polyimine Bearing Phenylacetylene Units.

In this study, a Schiff base was synthesized by the condensation reaction of 4-bromobenzaldehyde and 4-aminophenol. Then, phenylacetylene substituted Schiff base monomer (IPA) was obtained by HBr elimination reaction of IPA with phenylacetylene through Sonogashira reaction. IPA was polymerized via chemical oxidative polycondensation reaction. FT-IR and NMR measurements were used for the structural analyses of the synthesized substances. Fluorescence and UV–Vis analyses were carried out for optical characterization. Electrochemical characteristics, electrical conductivities and thermal properties were determined using cyclic voltammetry (CV), four-point probe conductometer, TG-DTA and DSC methods. The main purpose of the present study was to investigate the effects of phenylacetylene bearing units on the properties of conjugated aromatic polyimines. The spectral analysis signified a green light emission behavior when irradiated at different wavelengths. Combined with fluorescent behavior and good thermal stability, the electrical conductivity was found to be very crucial for π-conjugated polymer.

Synthesis and characterization of oligo-4-[(pyridin-3-ylimino)methyl]phenol

The oxidative polycondensation of 4-[(pyridin-3-ylimino)methyl]phenol (4-PIMP) with O2, H2O2, and NaOCl was studied in an aqueous alkaline medium between 50°C and 90°C. Oligo-4-[(pyridin-3-ylimino)methyl]phenol (O-4-PIMP) prepared was characterized by 1H-NMR, 13C-NMR, FT-IR, UV-VIS, size-exclusion chromatography, and elemental and thermal analyses techniques. At the optimum reaction conditions, the yield of O-4-PIMP was 18.9%, 39.4%, and 46.8% using H2O2, O2, and NaOCl oxidant, respectively. According to the TG analysis, the initial degradation temperature of O-4-PIMP was 218°C, which was by 50°C higher than that of 4-PIMP. Thermal analyses of 4-PIMP and O-4-PIMP were carried out in N2 atmosphere at 15–1000°C. The highest occupied molecular orbital, the lowest unoccupied molecular orbital, and electrochemical energy gaps of 4-PIMP and O-4-PIMP were determined from the onset potentials for n-doping and p-doping, respectively. Also, optical band gaps of 4-PIMP and O-4-PIMP were determined according to UV-VIS measurements.

Synthesis, Characterization, and Thermal Properties of Oligo-2-Hydroxyphenylbenzaldimine

Abstract In this study, the oxidative polycondensation reaction conditions of 2-hydroxyphenylbenzaldimine (HPBA) with air oxygen and NaOCl were studied in an aqeous alkaline medium between 50 and 90°C. The product was characterized by 1H-NMR, FT-IR, UV-Vis, size exclusion chromatography (SEC), and element analysis techniques. Solubility testing of oligo-2-hdroxyphenylbenzaldimine was investigated by organic solvents such as DMF, THF, DMSO, methanol, ethanol, CHCl3, CCl4, toluene acetonitrile, ethyl acetate, conc. H2SO4, and aqueous alkaline solution. 2-Hydroxyphenylbenzaldimine (96%) was converted to oligomer by oxidation in an aqueous alkaline medium. According to solubility in water, oligo-2-hydroxyphenylbenzaldimine separated into two fractions: oligo-2-hydroxyphenylbenzaldimine (OHPBA-I, undissolved in water) and oligo-2-hydroxyphenylbenzaldimine (OHPBA-II, dissolved in water). According to the SEC technique, the number average molecular weight (M n), mass average molecular weight (M w), and polydispersity index (PDI) values of OHPBA-I and OHPBA-II were found to be 2166 g mol−1, 2591 g mol−1, and 1.196; 1736 g mol−1, 2509 g mol−1, and 1.445, respectively. Also, differential thermal analysis (DTA) and thermo gravemetric analyses (TGA) were shown to be stable of oligo-2-hydroxyphenylbenzaldimine against thermo-oxidative decomposition. The weight loss of OHPBA was found to be 93.63% at 1000°C.