Aminopiperidine based complexes for lactide polymerisation
Herein we report the synthesis and characterisation of a series of salalen and salan ligands derived from 2-(aminomethyl)piperidine. Depending on the choice of starting salicylaldehyde, a bicyclic salan type ligand ( 1-3 H 2 ) or imino salalen type ligand ( 4-6 H, 7-9 H 2 ) were prepared. The ligand...
Saved in:
Published in: | Dalton transactions : an international journal of inorganic chemistry 2016-01, Vol.45 (12), p.5374-5387 |
---|---|
Main Authors: | , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
Summary: | Herein we report the synthesis and characterisation of a series of salalen and salan ligands derived from 2-(aminomethyl)piperidine. Depending on the choice of starting salicylaldehyde, a bicyclic salan type ligand (
1-3
H
2
) or imino salalen type ligand (
4-6
H,
7-9
H
2
) were prepared. The ligands were successfully complexed to group 4 metals and aluminium; with hafnium and zirconium octahedral complexes, M(
1-3
)
2
, were realised; whilst with aluminium tetrahedral and trigonal bipyramidal complexes, Al(
1-9
)Me
x
(
x
= 1,2), were isolated. The complexes have been characterised in solution
via
1
H and
13
C{
1
H} NMR spectroscopy and in the solid state by X-ray crystallography. The group 4 complexes were observed to have a
fac
-
fac
arrangement of ligands and there were two isomers present when
3
H
2
was ligated. The imino aluminium complexes Al(
7-9
)Me were isolated as a mixture of diastereoisomers. The resultant complexes were trialed in the ring opening polymerisation of
rac
-lactide with both heterotactic and isotactic PLA being demonstrated. Tacticity was found to be dependent on the nature of the ligand and metal used; the M(
1-3
)
2
complexes were generally found to have a heterotactic preference (
P
r
= 0.67-0.76) and the aluminium polymerisation outcome was dictated more by the steric influence of the ligand, particularly for Al(
4
/
6
)Me
2
/Al(
7
/
9
)Me.
A series of new ligands based on a 2-(aminomethyl)piperidine motif have been prepared. An interesting diversity in structure is observed, all complexes have been trialled for the polymerisation of
rac
-lactide. |
---|---|
ISSN: | 1477-9226 1477-9234 |
DOI: | 10.1039/c5dt04695e |