Chalcone-based molecules: Experimental and theoretical studies on the two-photon absorption and molecular first...

Area of Science:

• Materials Science
• Organic Chemistry
• Nonlinear Optics

Background:

• Chalcones are versatile organic compounds with significant nonlinear optical (NLO) properties.
• Understanding structure-property relationships in chalcones is crucial for designing advanced optical materials.
• Previous studies have explored various chalcone derivatives, but systematic investigation of specific substituents is ongoing.

Purpose of the Study:

• To synthesize and characterize five novel chalcone-based molecules.
• To investigate the nonlinear optical properties, specifically two-photon absorption (TPA) and molecular hyperpolarizability, of these compounds.
• To correlate molecular structure with observed NLO behavior and validate findings with theoretical calculations.

Main Methods:

• Synthesis of chalcone derivatives (C-3 to C-7) via Claisen-Schmidt condensation.
• Experimental determination of TPA cross-sections (σ^TPA) using the Z-scan technique with femtosecond pulses.
• Experimental determination of first molecular electronic hyperpolarizabilities (β^HRS) using hyper-Rayleigh scattering (HRS) with picosecond pulses.
• Theoretical calculations using time-dependent density functional theory (TD-DFT) to simulate spectra and predict β^HRS.

Main Results:

• Compound C-7 displayed the highest TPA cross-section (40 GM) for the HOMO-LUMO transition, while C-6 had the lowest (13 GM).
• Compound C-4 exhibited the maximum first molecular hyperpolarizability (38 × 10^-30 cm⁴ statvolt^-1), and C-3 showed the minimum (16 × 10^-30 cm⁴ statvolt^-1).
• TD-DFT calculations successfully simulated absorption spectra and predicted hyperpolarizability values, aligning with experimental data.

Conclusions:

• The synthesized chalcone derivatives possess significant nonlinear optical properties.
• Molecular structure, particularly the presence of methoxy and naphthyl groups, influences TPA cross-section and hyperpolarizability.
• These findings highlight the potential of these chalcones for applications in optoelectronics and photonics.