ZnO nanoparticles have been synthesized by using biodegradable natural biopolymer viz. Gum Tragacanth. This single step approach is very cost effective and reproducible. The reaction time and concentration of precursor zinc acetate play a major role in the nature and growth of ZnO nanoparticles. ZnO nanoparticles were characterized by X-ray diffraction, SEM, FTIR, EDAX, UVvisible spectroscopy and TEM. ZnO nanoparticles with 20-30 nm in diameter and hexagonal morphology were found; dispersed uniformly. Raman spectrum shows the mode E 2 high at 437 cm ¡1 that is related to the vibration of wurtzite Zn-O bond in crystal structure of ZnO. The space between adjacent lattice fringes is » sharp 2.42 A . UV-visible absorption spectrum shows the sharp absorption band at 308 nm assigned to the intrinsic transition from valance band to conduction band. The ZnO nanoparticles display superior catalytic activity of conversion of aldehyde to acid as compared to bulk-ZnO material, because of high surface area of ZnO nanoparticles. A trace amount of ZnO nanoparticles catalyst required for organic conversion. The ZnO nanoparticles as catalyst are highly stable, recyclable and efficient in its activity.

Abstract. The catalytic performance study of polyindole as a heterogeneous catalyst is reported for the synthesis of 3,3'-arylmethylene-bis-1H-Indole derivatives using various substituted aldehydes and indole under reflux reaction condition with good to excellent yield. Polyindole was synthesized by chemical oxidative polymerization using citric acid as a dopant. The synthesized polymer was well characterized by various spectroscopic techniques like FT-IR, XRD, FESEM, etc. The XRD pattern confirms the partially crystalline nature of polyindole. The FESEM images of polyindole revealed the formation of irregularly shaped particulate nature with size in the range of 0.2 to 6 micron. In FT-IR spectrum, the major peak at ∼ 3400 cm −1 indicates N-H stretching and at 1564−1624 cm −1 indicates C-C stretching of benzenoid ring of indole. The presence of peak at ∼ 3400 cm −1 indicates that the polymerization does not occur at nitrogen. The present protocol has certain advantages like recyclability, low loading of the catalyst, low-cost and efficient use of polyindole as a heterogeneous catalyst.

Poly(o-toluidine) doped with acrylic acid and without it was synthesized by using chemical oxidative polymerization technique. With the help of this method the polymer, poly(o-toluidine) was synthesized in the form of emeraldine salt. The oxidizing agent used for this method is the ammonium persulphate .The polymer products were characterized by UV-Visible and FTIR spectroscopy. The polymer, poly(o-toluidine) doped with acrylic acid was highly soluble in common organic solvents like m-cresol, NMP, DMF etc. The FTIR studies demonstrate that the acrylic acid doped poly(o-toluidine) shows broad and intense band at 3250-3000 cm -1 and 1160-1100 cm -1 account for the higher degree of doping. These results are well supported by conductivity measurements.

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