Progress of Ring-Opening Polymerization of Cyclic Esters Catalyzed by Iron Compounds

Abstract

Aliphatic polyesters such as polylactide (PLA) and polycaprolactone (PCL) have attracted much attention due to their prominent features of environmentally friendly materials with good biocompatibility and biodegradability. The commercialized PLA and PCL materials have been commonly prepared at high temperature using tin octanoate as catalysts: however, a higher temperature of polymerization potentially causes broader dispersity or/and lower molecular weight of the resultant polymers; most importantly, residual tin catalysts in the polymer products may be harmful to mammals and/or other living organisms in the ocean. As an abundant metal in the earth, not only is iron an essential element in the human body but also its compounds play important roles in pharmaceutical and polymerization chemistry. Recently, iron-based compounds have been proved to be efficient promoters of ring-opening polymerization of cyclic esters under mild conditions. Herein the progress of iron compounds used for the ring-opening polymerization (ROP) of cyclic esters is reviewed in order to develop practical catalysts for industrial processes in the future.

Metal-catalyzed stereoselective ring-opening polymerization of functional β-lactones: methylene-alkoxy-fluorinated polyhydroxyalkanoates unveil the role of non-covalent interactions

“…Such polymers exhibiting adjacent stereocenters having the same (isotactic structure), or opposite/alternating (syndiotactic/heterotactic structure) configuration, are indeed valuable for their tunable thermal, mechanical and degradation properties, in comparison with those exhibiting randomly distributed stereocenters (atactic structure). 1–4 Such polyesters typically include polylactide (PLA) and polyhydroxyalkanoates (PHAs), which are commonly prepared by ROP of lactide (LA) and β-lactones, respectively. One advantage (among others), over PLA, of the most common synthetic PHAs, which are derived from 4-substituted β-propiolactones (namely BPL FG s, FG = non-functional or functional group), arises from the FG exocyclic side chain.…”

Extended Hydrogen-Bonded Molybdenum Arrays Derived from Carboxylic Acids and Dianilines: ROP Capability of the Complexes and Parent Acids and Dianilines

“…Ideally, such catalysts should be highly active, inexpensive, and non-toxic. In the case of metals, the use of earth-abundant metals is now attracting attention [25]. In terms of molybdenum-based systems, the limited number that have thus far been reported tend to exhibit activity only at elevated temperatures, with early examples based on ammonium decamolybdate (melt at 150 • C) [26] or bis-(salicylaldhydato)dioxomolybdenum (110 • C in mesitylene) [27].…”

Elucidating the role of the o-methoxy group in the lower rim appended salicylideneamine substituents of calix[4]arene ligands on the molecular and electronic structures of dinuclear Fe(iii)-based diamond-core complexes

“…Fe(III) complexes are of high research interest because of their broad range of application in magnetic material fabrication, [1][2][3][4][5][6][7][8][9][10][11][12][13][14] chemical catalysis, [15][16][17][18][19][20][21][22] environmental protection, 23 biology and medicine. 24,25 Particularly, dinuclear Fe III 2 (μ 2 -O) 2 diamondcore species have attracted significant attention because of their high relevance in biocatalysis as cofactors of nonheme Fecontaining enzymes involved in O 2 fixation/activation.…”