Third-order nonlinear responses of symmetrical meso-substitutes porphyrin derivatives

Abstract

A series of porphyrin derivatives with an electron-accepting group (EAG), electron-donating group (EDG) attached in phenyl at a meso-position have been prepared and studied using the Z-scan technique. Due to EAG and EDG effects, the nonlinear refractive index, n2 and nonlinear absorption coefficient, β were measured with the order of 10−5(cm2/W)and 100(cm/W), respectively. Herein, Hydroxy and methoxy groups as electron donor indicate better result in comparison with electron accepting groups like methoxycarbonyl substituted in phenyl group or pyridine attached at a meso-position of porphyrin. Although the cobalt as substituted in porphyrin can increase nonlinearity responses, EDG has more effective in enhancement of nonlinearity than metal substituted. Nonlinear optical properties of the products were discussed to the effect of cobalt ion substitution at the core of porphyrin structure. The main results indicated some symmetric porphyrins can have higher nonlinearity responses than some asymmetric porphyrins. Considering results, symmetric porphyrins can more improve nonlinearity responses than metal substituted in porphyrins. The good results of these type of porphyrins causes to be a good candidate in nonlinear optical devices.