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self-assisted stereospecific polymerization of unmasked polar 4-methylthio-1-butene

Science China Chemistry 2019年第6期62卷 761-766页

作者： Yunjie Chai Chunji Wu Dongtao Liu Mingtao Run Dongmei Cui College of Chemistry and Environmental Science Hebei University State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences

Stereospecific polymerization of polar olefins has always been an attractive but challenging project because the Lewis basic polar groups of monomers are usually poisonous to the Lewis acidic metal centers of the catalysts. In this contribution,thiophene-fused cyclopentadienyl scandium complexes 1-3 were successfully synthesized. Combined with alkylaluminium and organoborate, these complexes showed extremely low activity and no selectivity for 1-hexene polymerization. Surprisingly,highly stereo-selective coordination polymerization of unprotected polar 4-methylthio-1-butene has been achieved in high activity for the first time under the same polymerization conditions. High-molecular-weight(M_n=110×10~3) and perfectly syndiotactic(rrrr>99%) poly(4-methylthio-1-butene)(P(MTB)) was afforded. Thus the methylthio-group-assisted mechanism that the unmasked methylthio group promoted the polymerization through σ-π chelation to the active scandium center together with the vinyl group was proposed. Moreover, the methylsulfonyl functionalized syndiotactic poly(1-butene) was also easily prepared by the oxidation of P(MTB). These results provided a new route for the synthesis of functionalized stereo-regular polyolefins.

关键词： self-assisted polymerization stereoselectivity polar α-olefin rare-earth metal catalyst functionalized poly(1-butene)

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Error-heralded generation and self-assisted complete analysis of two-photon hyperentangled Bell states through single-sided quantum-dot-cavity systems

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Science China(Physics,Mechanics & Astronomy) 2019年第7期62卷 46-54页

作者： YanYan Zheng LeiXia Liang Mei Zhang Department of Physics Applied Optics Beijing Area Major Laboratory Beijing Normal University

Hyperentangled-Bell-state analysis(HBSA) is critical for high-capacity quantum communication. Based on a recent proposal by Wang et al. [Opt. Express 24, 28444(2016)], we design two independent schemes for error-heralded deterministic generation and self-assisted complete HBSA of two-photon systems entangled in both polarization and spatial-mode degrees of freedom(DOFs).Unlike previous programs, we firstly propose an error-heralded block with a singly charged quantum dot inside a single-sided optical microcavity, with which errors due to imperfect interactions between photons and quantum dot systems can be *** error-heralded block, ensures that the fidelity of the two schemes for hyperentangled-Bell-state generation and complete HBSA reaches unity. Moreover, hyperentanglement makes it possible to analyze the polarization state with the assistance of the measured spatial-mode state. The self-assisted mechanism of HBSA greatly simplifies the analytical process and significantly relaxes the requirements of nonlinearities. Therefore, these schemes promise to be implemented more easily in experiments,taking a step closer to long-distance high-capacity quantum communication.

关键词： quantum hyperentanglement error-heralded self-assisted high-capacity quantum communication

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