ω-Phenoxyalkyl substituted bis(indenyl)zirconium dichloride complexes as catalysts for homogeneous ethylene polymerization
摘要:
Nine bis(indenyl) zirconium dichloride complexes of the type [C9H6-(CH2)(n)-O-Ar](2)ZrCl2 (n = 3-5; Ar = Ph, t-Bu-Ph) were synthesized, characterized, activated with methylalumoxane (MAO) and tested for ethylene polymerization. Structure-property-relationship studies showed that the activities of the catalysts depend on the length of the bridging chain between the indenyl and the phenoxy group as well as on the bulk at the phenoxy substituent. A t-Bu substituent at the ortho position of the phenoxy group (5a/MAO) gives a much higher catalyst activity (27,500 kg PE/mol cat h) than the isomer 8a/MAO with a t-Bu substituent at the para position of the phenoxy group (16,700 kg PE/mol cat h). Obviously substituents in the ortho position of the phenyl ring generate a bulkier catalyst cation and this can keep the MAO anion at a further distance to allow easier ethylene coordination and chain growth in the polymerization steps. The mono substituted bis(indenyl) complex (C9H7)[C9H6-(CH2)(4)-O-4-t-Bu]ZrCl2 shows lower activity (11,700 kg PE/mol cat h) than 8a indicating that the electronic effect is dominating in this type of catalysts. (C) 2015 Published by Elsevier B.V.
当纹状体中的多巴胺 (DA) 浓度下降到 20% 左右时,就会出现帕金森病 (PD) 的临床症状。对组胺 H 3受体 (H 3 R) 和 MAO B的同时抑制作用可增加大脑中的 DA 水平。设计了一系列化合物并在体外测试了人类 H 3 R ( h H 3 R) 亲和力和对人类 MAO B (hMAO B) 的抑制活性。结果显示化合物对两个生物靶标具有不同的活性。大多数化合物对h H 3 R ( K i > 500 nM) 的亲和力很差,但对 hMAO B (IC 50< 50 纳米)。经过进一步的体外测试(MAO B 抑制的方式、PAMPA 测定中的渗透性、对人星形胶质细胞系的细胞毒性),最有希望的双作用配体 1-(3-(4-(叔丁基)苯氧基)丙基) -2-甲基吡咯烷 ( 13 : h H 3 R: K i = 25 nM; hMAO B IC 50 = 4 nM) 被选择用于体内评估。化合物13在大鼠中的研究,剂量为