Investigation of the Structural, Geometric, Spectroscopic, and Nonlinear Optical Properties of (E)-2-(2,4-dihydroxybenzylidene) thiosemicarbazone and (E)-2-[(1H-indol-3-yl)methylene] thiosemicarbazone complexes: A DFT Study

Abstract

The optimized molecular geometries, vibrational frequencies, and both ¹H and ¹³C NMR spectra of (E)-2-(2,4-dihydroxybenzylidene)thiosemicarbazone (1) and (E)-2-[(1H-indol-3-yl)methylene]thiosemicarbazone (2) complexes were investigated using density functional theory (DFT) methods at the HSEh1PBE/6–311++G(d,p) and B3LYP/6–311++G(d,p) levels. NMR chemical shifts play a crucial role in elucidating the relationship between molecular structure and electronic properties. In addition, frontier molecular orbitals (FMOs) are essential for understanding the reactivity, as well as the electrical and optical properties, of molecules. The FMOs and related global reactivity descriptors—chemical hardness (η), electronegativity (χ), chemical potential (μ), and softness (S)—were also calculated using the same computational methods. Density Functional Theory (DFT) calculations were performed to investigate the nonlinear optical (NLO) properties of complexes 1 and 2. The results indicate that both complexes exhibit promising NLO behavior, with high second harmonic generation (SHG) efficiency.

Keywords

• Density functional theory
• Molecular geometry
• Infrared
• Nuclear magnetic resonance.

(E)-2-(2,4-dihidroksibenziliden)tiyosemikarbazon ve (E)-2-[(1H-indol-3-il)metilen]tiyosemikarbazon komplekslerinin yapısal, geometrik, spektroskopik ve doğrusal olmayan optik özelliklerinin incelenmesi: Bir DFT çalışması

Abstract

(E)-2-(2,4-dihidroksibenziliden)tiyosemikarbazon (1) ve (E)-2-[(1H-indol-3-il)metilen]tiyosemikarbazon (2) komplekslerinin optimize edilmiş moleküler geometrileri, titreşim frekansları ve hem ¹H hem de ¹³C NMR spektrumları, HSEh1PBE/6–311++G(d,p) ve B3LYP/6–311++G(d,p) seviyelerinde yoğunluk fonksiyonel teorisi (DFT) yöntemleri kullanılarak incelenmiştir. NMR kimyasal kaymaları, moleküler yapı ve elektronik özellikler arasındaki ilişkiyi aydınlatmada çok önemli bir rol oynar. Ek olarak, sınır moleküler orbitaller (FMO'lar), moleküllerin reaktivitesinin yanı sıra elektriksel ve optik özelliklerini anlamak için de gereklidir. Aynı hesaplama yöntemleri kullanılarak FMO'lar ve ilgili küresel reaktivite tanımlayıcıları—kimyasal sertlik (η), elektronegatiflik (χ), kimyasal potansiyel (μ) ve yumuşaklık (S)—hesaplandı. 1 ve 2 komplekslerinin doğrusal olmayan optik (NLO) özelliklerini incelemek için Yoğunluk Fonksiyonel Teorisi (DFT) hesaplamaları yapıldı. Sonuçlar, her iki kompleksin de yüksek ikinci harmonik üretim (SHG) verimliliği ile umut vadeden NLO davranışı sergilediğini göstermektedir.

Keywords

• Yoğunluk fonksiyonel teorisi
• Moleküler geometri
• Kızılötesi
• Nükleer manyetik rezonans.

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