Synthesis of four pyrene-containing chalcone derivatives: Achieving excellent third-order nonlinear optical properties by optimizing halopyridines

Four chalcone derivatives 3a-3d based on pyrenyl donor and different halopyridyl acceptors were synthesized successfully. The resultant chromophores 3a-3d were characterized by nuclear magnetic resonance (NMR), high resolution mass spectra (HR-MS) and ultraviolet (UV) spectra. The theoretical calculations and thermal properties of the materials 3a-3d were systematically studied to illustrate structure-performance relationship. Further, a novel and unique method, 4f phase coherent imaging technology, was introduced to investigate the third-order nonlinear optical properties of title compounds 3a-3d with 4 ns laser pulses at 460 nm. The thermal properties, the theoretical calculations and the experimental results consistently indicate that the compound 3b, namely 3-(5-bromopyridin-2-yl)-1-(pyren-1-yl) prop-2-en-1-one, is a more promising candidate for optoelectronic and nonlinear optical devices. Its third-order nonlinear absorption coefficient (β), refraction index (n2) and polarization (χ(33)) are found to be up to such order of magnitude as 10−9 m/W, 10−16 m2/W and 10−11 esu, respectively.