Pusat Pengajian Sains Fizik - Tesis

Browse

Browsing Pusat Pengajian Sains Fizik - Tesis by Author "Ai, Wong Qin"

Now showing 1 - 1 of 1
  • Thumbnail Image
    Publication
    Synthesis, Characterization, Structure-Property Relationship And Non-Linear Optical (Nlo) Studies Of Halogenated Chalcones
    (2025-05)
    Ai, Wong Qin
    The influence of electron-withdrawing (ew) and electron-donating (ed) substituents on chalcone derivatives concerning the photophysical and third-order non-linear optical (nlo) properties was comprehensively studied using a combination of experimental and computational approaches. Three series with a total of eleven halogenated chalcone compounds, which include thienoyl- and benzoyl-based chalcones, were designed and synthesized. Characterization was performed using ftir and nmr spectroscopies, whereas crystal structures were investigated using scxrd analysis. Quantum-chemical studies revealed that changes in electronic properties are driven by substituent effects, including ed/ew character, electron delocalization, aromaticity and polarity govern. Derivatives with strong edgs and extended ring system exhibited higher molecular polarity, cyanine-like bond length alternation (bla) in enone moiety and narrower homo-lumo gap (< 3.7 ev). Uv-vis absorption spectroscopy confirms broad transparency (> 500 nm) across all derivatives, indicating their suitability for optical applications. Hole-electron analysis, ifct spectrum and aatcm heat map revealed excitation mechanisms governed by substituent positioning. Para-substituted edgs on b-ring facilitated long-distance electron redistribution, whereas steric hindrance from substituents proximal to π-conjugation bridge weakened charge delocalization.