Crystal growth, spectral, structural and optical studies of π-conjugated stilbazolium crystal: 4-bromobenzaldehyde-4'-N'-methylstilbazolium tosylate

Static/dynamic first and second order hyperpolarizabilities, optimized structures, IR, UV-Vis, 1H and 13C NMR spectra for effective charge transfer compounds: A DFT study

The effective charge transfer compounds, 4-N,N-dimethylamino-4'-N'-methyl-stilbazolium m-trifluoromethylbenzene-sulfonate (DSMFS) and 4-N,N-dimethylamino-4'-N'-methyl-stilbazolium p-trifluoromethylbenzene-sulfonate (DSPFS), were simulated in terms of geometric structure, IR, UV-Vis, ¹H NMR and ¹³C NMR spectra. UV-vis spectra for both molecules give two peaks at 290 and 436 nm assigned as n-π* and π-π* transitions. The HOMO-LUMO energy gap for DSMFS (2.8174 eV) was calculated as lower than that of DSPFS (4.6649 eV). The detailed frontier molecular orbital analysis also indicated that the intra- and inter-molecular charge transfers occur in DSMFS and DSPFS. The static and dynamic (ω = 532 and 1064 nm) nonlinear optical properties were also investigated by using B3LYP/6-311++G(d,p) level. Static first and second order hyperpolarizabilities (β and γ) of DSMFS were obtained 1.5726 × 10^-28 esu and 271.63 × 10^-36 esu, and those for DSPFS were obtained as 1.5528 × 10^-28 esu and 303.31 × 10^-36 esu. The dynamic β and γ were obtained as higher than the static corresponding parameters. However, the increasing wavelength in dynamic NLO calculations led to a decrease in β and γ parameters.

Growth, structural, thermal, dielectric and optical studies on HBST crystal: A potential THz emitter

The efficient organic nonlinear optical material 4-hydroxy benzaldehyde-N-methyl 4-stilbazolium tosylate (HBST) was grown from methanol by slope nucleation method combined with slow cooling (SNM-SC) for the first time. The optimum growth conditions based on the cooling rate was further investigated. The single crystal X-ray diffraction (XRD) revealed that the chromophores of HBST crystal make an angle of about 33° with respect to the a-axis, which is close to the optimum of Terahertz (THz)-wave generation and electro-optics applications. NMR and FT-IR spectral studies have been performed to ascertain various functional groups present in the sample. Futhermore, the thermal stability and decomposition stages were analyzed through TG-DTA and DSC techniques. The dielectric constant and dielectric loss of HBST crystal have been studied. Critical optical properties like the absorption coefficient, refractive index, cut-off wavelength and band gap energy were calculated. Photoluminescence (PL) exication studies indicated green emission occured at 507nm. All the results of HBST crystal make it a promising candidate in the fields of optoelectronic and the generation of THz.

Studies on the growth, structural, spectral and third-order nonlinear optical properties of ammonium 3-carboxy-4-hydroxy benzenesulfonate monohydrate single crystal

An organic nonlinear optical bulk single crystal, Ammonium 3-carboxy-4-hydroxy benzenesulfonate monohydrate (ACHBS) was successfully grown by solution growth technique. Single crystal X-ray diffraction study confirms that, the grown crystal belongs to P21/c space group. Powder X-ray diffraction and high resolution X-ray diffraction analyses revealed the crystallinity of the grown crystal. Infrared spectral analysis showed the vibrational behavior of chemical bonds and its functional groups. The thermal stability and decomposition stages of the grown crystal were studied by TG-DTA analysis. UV-Visible transmittance studies showed the transparency region and cut-off wavelength of the grown crystal. The third-order nonlinear optical susceptibility of the grown crystal was estimated by Z-scan technique using He-Ne laser source. The mechanical property of the grown crystal was studied by using Vicker's microhardness test.