The need for homogenous titanium compounds as catalysts has been increasing gradually due to their non-toxic properties and catalytic activities. In this article, titanium salicylate complexes 1–7 were produced by reaction of titanium(IV) isopropoxide with salicylic, 5-chlorosalicylic, 5-nitrosalicylic, 4-hydroxysalicylic, 3-methylsalicylic, 4-methylsalicylic, and 3,5-ditertbutylsalicylic acids with 1:2 mol ratio in isopropanol. These complexes 1–7 were structurally characterized using a variety of instrumental techniques such as high resolution mass spectrometry (HRMS), FTIR and NMR spectroscopies, elemental and thermogravimetric (TG) analysis. Also, complexes 1–7 were applied as catalysts in the ring-opening polymerization (ROP) of ε-caprolactone and were highly efficient catalysts. Polycaprolactone (PCL) was analyzed using NMR spectroscopy, differential scanning calorimetry (DSC), and gel permeation chromatography (GPC) techniques. In the ROP reactions of ε-CL monomer, the catalysts containing electron donating groups on salicylate ligands were more effective than the catalysts containing electron withdrawing groups.

Graphic Abstract

中文翻译：

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无毒环保的钛配合物及其对and-己内酯聚合的影响

由于其无毒特性和催化活性，对均相钛化合物作为催化剂的需求已逐渐增加。在本文中，水杨酸钛配合物1-7是通过异丙醇钛（IV）与水杨酸，5-氯水杨酸，5-硝基水杨酸，4-羟基水杨酸，3-甲基水杨酸，4-甲基水杨酸和3,5-二叔丁基水杨酸反应制得的在异丙醇中的摩尔比为1：2。使用各种仪器技术，例如高分辨率质谱（HRMS），FTIR和NMR光谱，元素和热重（TG）分析，对这些配合物1-7进行了结构表征。此外，复合物1–7将其用作ε-己内酯的开环聚合（ROP）中的催化剂，是高效的催化剂。使用NMR光谱，差示扫描量热法（DSC）和凝胶渗透色谱（GPC）技术分析了聚己内酯（PCL）。在ε-CL单体的ROP反应中，在水杨酸酯配体上包含给电子基团的催化剂比包含吸电子基团的催化剂更有效。

图形摘要