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ABSTRACT:In this study, oligo-2-hydroxy-1-naphthaldehyde (OHNA) was synthesized from the oxidative polycondensation of 2-hydroxy-1-naphthaldehyde (HNA) with air oxygen, NaOCl, and H 2 O 2 in an aqueous alkaline medium at 50 -95°C. We determined the products and the oxidative polycondensation reaction conditions of HNA with oxidants such as air oxygen, NaOCl, and H 2 O 2 . In these reactions, H 2 O 2 was more active than air oxygen and NaOCl and their optimum reaction conditions were studied. The products were characterized by 1 H-NMR, FTIR, UV-visible, and elemental analysis. The respective number-average molecular weight, mass-average molecular weight, and polydispersity index values of OHNA and its Schiff base oligomers (compounds 1, 2, and 3) were found to be 500 g mol Ϫ1 , 1880 g mol Ϫ1 , and 3.75 for OHNA; 670 g mol Ϫ1 , 2490 g mol Ϫ1 , and 3.71 for compound 1; 390 g mol Ϫ1 , 1080 g mol Ϫ1 , and 2.77 for compound 2; and 320 g mol Ϫ1 , 670 g mol Ϫ1 , and 1.85 for compound 3. At the optimum reaction conditions, the yields of the reaction products were found to be 77.0% O 2 , 78.0% H 2 O 2 , and 75.4% NaOCl. About 80% of the HNA was converted into OHNA. In addition, new Schiff based oligomers were synthesized from the condensation reaction of OHNA with p-aminophenol, triethyleneglycol bis(4-aminophenyl ether), and aniline and their structures and properties were determined. Thermogravimetric and dynamic thermal analyses showed OHNA and its Schiff base oligomers to be stable against thermooxidative decomposition. The weight losses of OHNA and its Schiff base oligomer compounds 1, 2, and 3 were found to be 5% at 175, 225, 190, and 230°C, respectively; 50% at 900, 590, 650, and 620°C, respectively; and 60, 80, 85, and 82%, respectively, at 1000°C.

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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.

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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, 1 H-NMR, and 13 C-NMR analyses. The 1 H-NMR and 13 C-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 (E 0 g ) and optical (E g ) 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.