Structural design and characterization of a new type of organic nonlinear optical flavanone crystal

• Published in: Journal of molecular structure 2025-02, Vol.1322, p.140305, Article 140305
• Main Authors: Zhai, Yumeng, Ma, Jinkang, Liu, Xinran, Xuan, Fanghao, Hu, Kaiwen, Wang, Shoubo, Feng, Xiaoyu, Cao, Lifeng, Teng, Bing
• Format: Article
• Language: English
• Subjects: Chalcone; Flavanone; Molecular design approach; Molecular twisting; Nonlinear optical crystal
• ISSN: 0022-2860
• DOI: 10.1016/j.molstruc.2024.140305

•Two new crystals based on chalcone and flavanone were designed and grown.•The nonlinear properties of flavanone derivatives were reported for the first time, and the second-order nonlinear efficiency is 11 times that of the standard KDP.•Improvement of nonlinear optical properties by changing the degree of molecular torsion.•The crystal has excellent optical properties, with a high transmittance of 88 % in the range of 650nm-1 650nm. Two new crystals were designed and obtained: the chalcone derivative HMMP (1-(2‑hydroxy-4-methoxyphenyl)-3-(4-(methylthio)phenyl)prop‑2-en-1-one) and the flavanone derivative 7M4MC (7‑methoxy-2-(4-(methylthio)phenyl)chroman-4-one). Yellow bulk 7M4MC single crystal with dimensions of 3 × 2 × 1 mm3 and orange-yellow needle-like HMMP single crystal were grown by solution evaporation. 7M4MC crystal belongs to the P21 space group of the monoclinic structure, which has a non-centrosymmetric structure. HMMP crystal monoclinic, belongs to the P21/m space group with a centrosymmetric structure. In the 7M4MC molecule, the methoxy and methylthio groups act as electron donors (D) and the carbonyl group acts as an electron acceptor (A), forming a d-π-A-π-D structure with an electron gradient. 7M4MC exhibits a high degree of second-harmonic generation intensity (11 × KDP), a broad transmission range (600–1600 nm, >88 %), an elevated optical energy bandgap (Eg = 2.57 eV), high thermal stability (Tm = 105 °C) and excellent dielectric properties (εr ≈ 2.1). This work not only provides two new crystals but also offers a viable molecular design option by changing the degree of intramolecular distortion by altering the backbone structure. [Display omitted]