Structural and optical properties of new organic crystal 1-[4-(methylsulfanyl) phenyl]-3-(2,4,5-trimethoxyphenyl) prop-2-en-1-One for optical limiting applications

摘要

A new organic crystal belonging to chalcone family 1-[4-(methylsulfanyl) phenyl]-3-(2,4,5-trimethoxyphenyl) prop-2-en-1-One (4MSTP) with molecular formula C_(19)H_(20)O_4S has been synthesized by Claisen Schimidt condensation method. 4MSTP was crystallized by slow evaporation technique using methanol solution at ambient temperature. Crystals of 4MSTP were characterized by Fourier transform infrared (FTIR) spectroscopy, NMR spectroscopy, single crystal and powder X-ray diffraction (XRD) technique, thermal analysis and UV-Vis spectroscopy. Nonlinear optical properties of 4MSTP crystals were investigated using Nd:YAG laser at 532 nm wavelength. The presence of functional groups were confirmed by FTIR and the structural elucidation was done using proton and carbon NMR spectral analysis. The X-ray diffraction peaks are indexed by the least square fit method. From the single crystal XRD study it is found that 4MSTP crystallizes in monoclinic system with a centro symmetric space group P21/c. The unit cell parameters of the crystal are: a = 19.2413(6) ?, b = 8.9504(3) ?, c = 10.3608(4) ?, α = 90°, β = 104.45°(2) and γ = 90°. Linear optical studies were carried out using UV visible spectral technique. The studies revealed that the 4MSTP crystals can be exploited for the nonlinear optical applications. TGA-DSC experiments indicated that the melting point of the material is 165.91 °C and the crystals showed absence of phase transition before melting point. Calculated excited state absorption (σ_(ex)) is greater than the ground state absorption (σ_g) and thus the condition for Reverse Saturable Absorption (RSA) is achieved in 4MSTP. The open aperture Z-Scan curve showed minimum transmittance at the focus and hence 4MSTP crystals have maximum nonlinear absorption. The variation of nonlinear transmission with input intensity of laser showed that 4MSTP crystals can be used as an optical limiter.