Browsing by Author "Zhang, Sai (TTU)"
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Item A new chiral phenomenon of orientational chirality, its synthetic control and computational study(2023) Jin, Shengzhou; Xu, Ting; Tang, Yao (TTU); Wang, Jia Yin; Wang, Yu; Pan, Junyi; Zhang, Sai (TTU); Yuan, Qingkai (TTU); Rahman, Anis Ur (TTU); Aquino, Adelia J.A. (TTU); Lischka, Hans (TTU); Li, Guigen (TTU)A new type of chirality, orientational chirality, consisting of a tetrahedron center and a remotely anchored blocker, has been discovered. The key structural element of this chirality is characterized by multiple orientations directed by a through-space functional group. The multi-step synthesis of orientational chiral targets was conducted by taking advantage of asymmetric nucleophilic addition, Suzuki-Miyaura cross-coupling and Sonogashira coupling. An unprecedented catalytic species showing a five-membered ring consisting of C (sp2)-Br-Pd-C (sp2) bonds was isolated during performing Suzuki-Miyaura cross-coupling. X-ray diffraction analysis confirmed the species structure and absolute configuration of chiral orientation products. Based on X-ray structures, a model was proposed for the new chirality phenomenon to differentiate the present molecular framework from previous others. DFT computational study presented the relative stability of individual orientatiomers. This discovery would be anticipated to result in a new stereochemistry branch and to have a broad impact on chemical, biomedical, and material sciences in the future.Item Aggregation-induced polarization (AIP) of derivatives of BINOL and BINAP(2022) Tang, Yao (TTU); Yuan, Qingkai (TTU); Wang, Yu; Zhang, Sai (TTU); Wang, Jia-Yin; Jin, Shengzhou; Xu, Ting; Pan, Junyi; Guilbeau, Collin Ray (TTU); Pleasant, Alyssa Jenae (TTU); Li, Guigen (TTU)The relationship between optical rotations of small chiral molecules with water% in THF has been established. The typical aggregation co-solvent systems resulted in optical rotation amplification and adjustment, defined as aggregation-induced polarization (AIP). The AIP work can serve as a new tool to determine molecular aggregation, especially for those that cannot display aggregation-induced emission (AIE). Therefore, AIP and AIE are anticipated to complement each other. In addition, AIP can also serve as a new transmission tool providing adjusting right- or left-hand polarized lights of a series of individual wavelengths. Since chiral phosphine derivatives are among the most important ligands, this work would benefit research using chiral aggregates to control asymmetric synthesis and catalysts. Therefore, it will find many applications in chemical and materials sciences.Item Aggregation-Induced Polarization (AIP): Optical Rotation Amplification and Adjustment of Chiral Aggregates of Folding Oligomers and Polymers(2022) Tang, Yao (TTU); Zhang, Sai (TTU); Xu, Ting; Yuan, Qingkai (TTU); Wang, Jia-Yin; Jin, Shengzhou; Wang, Yu; Pan, Junyi; Griffin, Isaac (TTU); Chen, Daixiang; Li, Guigen (TTU)The phenomenon of aggregation-induced polarization (AIP) was observed showing optical rotation amplification and adjustment. The relationship between optical rotations of chiral aggregates of multilayered chiral folding oligomers and polymers with water% in THF (fw) has been established accordingly. New multilayered chiral oligomers were synthesized under the asymmetric catalytic systems established by our laboratory recently. These products were well-characterized by UV-vis, NMR, and MALDI-TOF spectra. Absolute stereochemistry (enantio- and diastereochemistry) was assigned by comparison with similar asymmetric induction by the same catalyst in our previous reactions. The present AIP work can serve as a new tool to determine chiral aggregates, especially for those that cannot display emission. AIP would also complement AIE-based CPL since AIP serves as a new tool providing enhanced right- or left-hand polarized lights with individual wavelengths. It will find many applications in chemical and materials science in the future.Item C(sp)-C(sp) Lever-Based Targets of Orientational Chirality: Design and Asymmetric Synthesis(2024) Xu, Ting; Wang, Jia Yin; Wang, Yu; Jin, Shengzhou; Tang, Yao (TTU); Zhang, Sai (TTU); Yuan, Qingkai (TTU); Liu, Hao (TTU); Yan, Wenxin; Jiao, Yinchun; Yang, Xiao Liang; Li, Guigen (TTU)In this study, the design and asymmetric synthesis of a series of chiral targets of orientational chirality were conducted by taking advantage of N-sulfinylimine-assisted nucleophilic addition and modified Sonogashira catalytic coupling systems. Orientational isomers were controlled completely using alkynyl/alkynyl levers [C(sp)-C(sp) axis] with absolute configuration assignment determined by X-ray structural analysis. The key structural element of the resulting orientational chirality is uniquely characterized by remote through-space blocking. Forty examples of multi-step synthesis were performed, with modest to good yields and excellent orientational selectivity. Several chiral orientational amino targets are attached with scaffolds of natural and medicinal products, showing potential pharmaceutical and medical applications in the future.Item Central-to-Folding Chirality Control: Asymmetric Synthesis of Multilayer 3D Targets With Electron-Deficient Bridges(2022) Jin, Shengzhou; Wang, Jia Ying; Tang, Yao (TTU); Rouh, Hossein (TTU); Zhang, Sai (TTU); Xu, Ting; Wang, Yu; Yuan, Qingkai (TTU); Chen, Daixiang; Unruh, Daniel (TTU); Li, Guigen (TTU)New multilayer 3D chiral molecules have been designed and synthesized asymmetrically through the strategy of center-to-multilayer folding chirality control and double Suzuki couplings. Individual diastereoisomers were readily obtained and separated via flash column chromatography. The key diastereoisomer was further converted into corresponding enantiomers. These enantiomers possess electron-deficient aromatic bridges layered with top and bottom aromatic scaffolds. X-ray structural analysis has unambiguously confirmed the configuration, and intermolecular packing results in regular planar patterns in solid crystals. The synthesis was achieved in a total of ten steps starting from commercially available starting materials.Item Four-layer folding framework: design, GAP synthesis, and aggregation-induced emission(2023) Zhang, Sai (TTU); Chen, Daixiang; Wang, Jia Yin; Yan, Shenghu; Li, Guigen (TTU)The design and synthesis of a type of [1 + 4 + 2] four-layer framework have been conducted by taking advantage of Suzuki–Miyaura cross-coupling and group-assisted purification (GAP) chemistry. The optimized coupling of double-layer diboronic esters with 1-bromo-naphth-2-yl phosphine oxides resulted in a series of multilayer folding targets, showing a broad scope of substrates and moderate to excellent yields. The final products were purified using group-assisted purification chemistry/technology, achieved simply by washing crude products with 95% EtOH without the use of chromatography and recrystallization. The structures were fully characterized and assigned by performing X-ray crystallographic analysis. UV–vis absorption, photoluminescence (PL), and aggregation-induced emission (AIE) were studied for the resulting multilayer folding products.