Related Experiment Video
Updated: Jan 9, 2026

Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes
Published on: November 21, 2017
Titanium Alkoxide Complexes of Phenoxy-Azo and Phenoxy-Imine Ligands for Cyclic Ester (Co)Polymerization Studies:
Wasan Joopor1,2, Worawat Wattanathana3, Chawakorn Chansaenroch1
1Laboratory of Catalysts and Advanced Polymer Materials, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
Abstract:
Two series of titanium complexes supported by monoanionic phenoxy-azo (1-7) and phenoxy-imine (8-12) ligands were successfully synthesized and fully characterized. X-ray structure analysis of the bis(phenoxy-azo)titanium complexes 1 and 4 revealed that the titanium atom was in a distorted octahedral geometry, with the trans-O, cis-N, cis-OiPr configuration. All complexes were active for the ring-opening polymerizations of rac-lactide, ε-caprolactone, and ε-decalactone. For rac-LA polymerization, the bis(phenoxy-azo)titanium complex bearing alkyl phenoxy substituents exhibited superior catalytic activity compared to its bis(phenoxy-imine)titanium analogue with identical substituents. In contrast, a reverse trend was observed upon introducing halogenated phenoxy substituents. Kinetic investigations revealed the origin of the diminished catalytic activity of the halogenated bis(phenoxy-azo)titanium complexes. Perfect diblock copolymers, poly(CL-b-rac-LA) and poly(CL-b-l-LA), were successfully synthesized via a sequential-feed copolymerization, while a single-feed copolymerization of rac-LA/l-LA and ε-CL afforded practically random copolymers. This study demonstrated that the catalytic activity of bis(phenoxy-imine)titanium complexes was enhanced by substituting the imine unit with an azo moiety, highlighting that catalytic activity can be fine-tuned through ligand design.
More Related Videos
09:22Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives
Published on: February 7, 2017
10:17Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
Related Concept Videos
Ziegler–Natta Chain-Growth Polymerization: Overview
Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)
Olefin Metathesis Polymerization: Acyclic Diene Metathesis (ADMET)
Similar to cross-metathesis, ADMET also involves the formation of metallacyclobutane intermediate by [2+2] cycloaddition of one of the double bonds of a terminal diene with...
Olefin Metathesis Polymerization: Overview
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists of a...
Preparation of Epoxides
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of peroxy acids to...
Complexometric Titration: Ligands