Molecular Structure Design, Crystal Growth, and Characterization of New Types of Organic Nonlinear Optical Chalcone Crystals

Abstract

Chalcone structures obtained by structural tailoring are an important class of molecular organic nonlinear optics (NLO) crystals that can be used for multiple purposes. In this work, two novel chalcone compound crystals with noncentrosymmetric structures, 6MN3MPP (C 21 H 18 O 3 , Pca2 1 ) and 6MN4MPP (C 21 H 18 O 3 , Pn), were designed and grown by extending the π-conjugation and structure-modifying strategy. On this basis, the second harmonic generation (SHG) efficiency, thermal stability, transmission spectra, dielectric constant, and photoluminescence properties of the crystal were characterized, and the hyperpolarizability of the crystal was theoretically calculated. The results show that the synthesized crystals exhibit higher crystal transparency (≥70%), higher melting point, and lower dielectric constant (ε r ≈ 6.5) compared with other reported chalcone NLO crystals. In particular, the SHG intensity of the 6MN3MPP crystal is 4.3 times higher than that of the KDP crystal. All of the results show that the two newly synthesized compounds have good application prospects as NLO crystals.

Synthesis and characterization of a new isoxazolone-based nonlinear optical crystal: MPMOI

“…The SHG properties of organic nonlinear optical crystals with similar ketone-methoxy group structures reported in recent years are listed in Table S2 †. When having the same electron donor CH 3 O– group, the SHG intensities of simple ketone structures, such as DMPP, 51 BMP, 52 and 6MN4MPP, 15 are 1–2 times that of KDP ( d 36 = 0.39 pm V −1 at 1064 nm) 53,54 /urea ( d 36 = 1.2 ± 0.1 pm V −1 at 1064 nm), 55 which are smaller than that of MPMOI. Besides, among molecule-type ketone-based nonlinear optical crystals, as shown in Table S2,† MPMOI shows a moderate second harmonic generation intensity.…”

“…[11][12][13] Compared to inorganic crystals, their organic counterparts also have promising applications in some specific regions (e.g., terahertz range) because of their superior macroscopic optical nonlinearity, ultrafast response time, and phase-matching capability. [14][15][16][17][18][19] In the past few decades, many organic nonlinear optical crystals have been discovered. [20][21][22][23][24][25][26][27][28] The selection of acceptors in the D-π-A structures is crucial in order to design organic nonlinear optical crystals with large nonlinear optical susceptibilities.…”

“…, terahertz range) because of their superior macroscopic optical nonlinearity, ultrafast response time, and phase-matching capability. 14–19…”

Non-Negligible Modulation Role of the Solvent in the Asymmetric Growth of α-Resorcinol

“…Nonlinear optical (NLO) crystals are widely used in laser frequency conversion, phase modulation, and optical signal holographic storage due to their large second-harmonic generation (SHG). , What is more is that organic polar crystals are expected to surpass inorganic crystals as the new generation of functional materials owing to their advantages of fast nonlinear optical coefficient response, high laser damage threshold, and strong molecular designability. − However, organic polar crystals inevitably fall into the growth dead zone or generate crystal defects during the incubation process, resulting in the formation of imperfect crystals. , Therefore, it is imperative to investigate the asymmetric growth of organic polar crystals in solution, which is influenced by many factors, such as supersaturation, solvent type, , and additive. , Among them, the solvent is non-negligible since it tends to change the growth behavior significantly.…”

Design Novel Chalcone Crystals for Enhancement of Nonlinear Optical Activity and Higher Molecular Structural Stability

“…Furthermore, in the 1,5-diphenylpenta-2,4-dien-1-one (DDO) series molecules based on the chalcone structure (Figure b), the hyperpolarizability β of the molecule is determined by the competition between the two electron donors (EDs) (R 1 and R 2 ) . Although the 6MN3MPP (C 21 H 18 O 3 , Pca 2 1 ) and 6MN4MPP (C 21 H 18 O 3 , Pn ) crystals and the 6MNPP (C 20 H 16 O 2 , Pca 2 1 ) crystal structure were reported, , which were designed from the chalcone configuration to the new configuration in Figure c, their NLO properties can still be improved and worth exploring.…”