scholarly journals Towards a selective synthetic route for cobalt amino acid complexes and their application in ring opening polymerization of rac-lactide

RSC Advances ◽  
2021 ◽  
Vol 11 (27) ◽  
pp. 16326-16338
Author(s):  
Andrés Castro Ruiz ◽  
Krishna K. Damodaran ◽  
Sigridur G. Suman
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Oxidation States ◽  
Synthetic Route ◽  
Coordination Properties ◽  
Amino Acid Complexes ◽  
Ligand Coordination

Catalysts based on Co, amino acids, and 2,2-bipyridine present an attractive and economic alternative in ring opening polymerization, and possess advantageous ligand coordination properties combined with a variety of accessible oxidation states and coordination geometries.

Use of samarium(III)–amino acid complexes as initiators of ring-opening polymerization of cyclic esters

2017 ◽  
Vol 75 (3) ◽  
pp. 1253-1263 ◽  
Author(s):  
Dimas A. Medina ◽  
Jesús M. Contreras ◽  
Francisco J. López-Carrasquero ◽  
Eduardo J. Cardozo ◽  
Ricardo R. Contreras
Keyword(s):  
Amino Acid ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Cyclic Esters ◽  
Amino Acid Complexes

A switchable dimeric yttrium complex and its three catalytic states in ring opening polymerization

2021 ◽  
Author(s):  
Shijie Deng ◽  
Paula L. Diaconescu
Keyword(s):  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Oxidation States ◽  
Cyclic Esters

A dimeric yttrium phenoxide complex can be oxidized in a stepwise fashion to access three oxidation states. The three states show different activity in the ring opening polymerization of cyclic esters and epoxides.

Biodegradable Polymers Derived from Amino Acids for Biological Applications

2010 ◽  
Vol 76 ◽  
pp. 30-35 ◽  
Author(s):  
Naomi Cohen-Arazi ◽  
Ilanit Hagag ◽  
Michal Kolitz ◽  
Abraham J. Domb ◽  
Jeoshua Katzhendler
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Ring Opening ◽  
Building Blocks ◽  
Ring Opening Polymerization ◽  
Microwave Assisted Synthesis ◽  
Hydroxy Acids ◽  
Natural Amino Acids ◽  
Direct Condensation ◽  
Positively Charged

Optically active α-hydroxy acids derived from amino acids have been synthesized and polymerized into new biodegradable polyesters. The variety of functional side chains enables the design of positively charged, negatively charged, hydrophobic and hydrophilic chiral building blocks or any combination of these constituents. Hydroxy acids of 15 natural amino acids were prepared with retention of configuration using a straightforward and reliable method of diazotization of α-amino acids. Polyesters were synthesized from these hydroxy acids by a number of methods: direct condensation in bulk, microwave assisted synthesis and ring opening polymerization. The molecular weight of the prepared polymers ranges between 2000 to 5000Da for the direct condensation and the microwave methods, whereas the ring opening polymerization results in high molecular weight polymers (20000 to 30000Da). The polymers were analyzed for their optical activity (Circular Dichroism Spectroscopy), thermal properties (DSC), solubility, molecular weight and polydispersity (GPC), and aqueous degradation. These polymers were tested for their compatibility to neuronal cells growth and differentiation.

Circular dichroism spectra of amino acid complexes. II. Chelated amino acid complexes with the CoN5O chromophore

1970 ◽  
Vol 23 (9) ◽  
pp. 1735 ◽  
Author(s):  
CJ Hawkins ◽  
PJ Lawson
Keyword(s):  
Amino Acids ◽  
Circular Dichroism ◽  
Amino Acid ◽  
Visible Region ◽  
Optically Active ◽  
Circular Dichroism Spectra ◽  
Amino Acid Complexes ◽  
Similar Series ◽  
Cotton Effects ◽  
Circular Dichroïsm

The circular dichroism spectra of a series of optically active (α-aminocarboxylato)tetraamminecobalt(111) complexes have been measured in aqueous solution, and in the presence of salts of polarizable anions. The observed spectra in the visible region have been analysed to determine the signs of the Cotton effects of the three components of the 1A1g ↔ 1T1g cobalt(111) transition. For L-amino acids, the transition with A2g(D4h) parentage is negative, and the two transitions with Eg(D4h) parentage have opposite signs. Published circular dichroism spectra of complexes of the type [Co(en)2(L-am)]2+ were similarly interpreted in terms of a perturbed tetragonal chromophore, and it was shown that the vicinal effect of the L-amino acids imposed the same signs onto the component transitions as for the tetraammines and for a similar series of pentaamminecobalt(111) complexes.

The role of ligand redox non-innocence in ring-opening polymerization reactions catalysed by bis(imino)pyridine iron alkoxide complexes

2017 ◽  
Vol 46 (38) ◽  
pp. 12971-12980 ◽  
Author(s):  
K. R. Delle Chiaie ◽  
A. B. Biernesser ◽  
M. A. Ortuño ◽  
B. Dereli ◽  
D. A. Iovan ◽  
...  
Keyword(s):  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Oxidation States ◽  
Polymerization Catalysts ◽  
Iron Based

The reactivity of iron-based ring opening polymerization catalysts is compared when the catalyst is in three different oxidation states.

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