Dynamic ring-opening polymerization, D-ROP: Applications in coordination polymers

Recent Advances in the Titanium-Based Catalysts for Ring-Opening Polymerization

At present, economic development and daily life cannot be separated from organic synthetic polymers. However, a large number of nondegradable polymers have caused serious pollution to the environment. It is necessary for sustainable development to use biodegradable materials instead of traditional polymers, but it is not yet comparable in performance and cost to the competitor it will replace. Therefore, there is a long way to go to develop effective synthesis methods. Through ring-opening polymerization, some cyclic monomers, such as ε-caprolactone or lactide, can be synthesized into biodegradable polymers, which can not only replace traditional synthetic polymers in some fields but also have applications in drug delivery, surgical consumables, human implant materials, bone materials, etc. Ring-opening polymerization is a potential candidate for solving environmental pollution. For ring-opening polymerization, catalysts are very important, among which titanium catalysts have attracted much attention because of their high efficiency, economy, and nontoxicity. In this paper, the development status of organotitanium compounds as ring-opening polymerization catalysts is reviewed, including the effects of different ligand structures on polymerization behavior and polymer structure, and its development trend is prospected. We hope that this review will be helpful for developing efficient ring-opening polymerization catalysts.

Supramolecular chemistry of organoplatinum(IV) complexes: A syndiotactic polymer with uracil substituents

The reaction of RCH2X with [PtMe2(DPA)], 1, (DPA = di-2-pyridylamine) has given [PtXMe2(CH2R)(DPA)] by cis oxidative addition to give 2a, when R = 6-uracil, X = Cl, or 3a, when R = CO2H, X = Br, but by a mixture of cis and trans oxidative addition to give 4a/4b when R = 4-C6H4CO2H, X = Br. The unusual cis stereochemistry of oxidative addition is rationalized thermodynamically by the formation of an intramolecular hydrogen bond in 2a and 3a but not 4a, and kinetically by the role of the ligand DPA NH group in hydrogen bonding to halide. Complex 2a in the solid state forms an unusual supramolecular syndiotactic polymer by forming two different intermolecular NH..O=C hydrogen bonds to neighbouring molecules.