Pyrazole based NLOphores: Synthesis, photophysical, DFT, TDDFT studies

• Novel pyrazole based push–pull dyes were synthesized and characterized.
• Photophysical properties estimated using experimental method are in good agreement with the theoretical results.
• DFT computation was performed for determination of nonlinear optical (NLO) properties.
• Pyrazole based dyes exhibited large second order hyperpolarizabilities.

A series of pyrazole based D-π-A derivatives have been synthesized from 3-(4-nitrophenyl)-1-pheny-1H-pyrazole-3-carbaldehyde with series of active methylene compounds. The dyes were well characterized by FT-IR, 1H NMR, 13C NMR, elemental analysis and mass spectroscopy. The synthesized dyes absorb in the range of 351–432 nm. Experimental absorption wavelengths for compounds are in good agreement with those predicted using the Time-Dependent Density Functional Theory (TD-DFT) [B3LYP/6-31G(d)]. Density Functional Theory calculations were performed to determine the static first hyperpolarizability (β0) and related properties (μ, α, Δα, β0 and γ) for pyrazole based “donor-π-acceptor” dyes 3a–3f, using B3LYP functional with 6-31G (d) basis sets at the ground state. The computed values for these dyes show high first order hyperpolarizability in the range 50.64–256.38 × 10−30 esu and second hyperpolarizability (γ) in the range of 235.71–1580.81 × 10−36 esu.

Figure optionsDownload as PowerPoint slide