Premium
Dynamic Aminal‐Based TPA Ligands
Author(s) -
Zhou Yuntao,
Yuan Yaofeng,
You Lei,
Anslyn Eric V.
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201500105
Subject(s) - chemistry , aminal , substituent , amine gas treating , dynamic covalent chemistry , covalent bond , stereochemistry , supramolecular chemistry , combinatorial chemistry , organic chemistry , molecule
The use of dynamic covalent reactions (DCRs) is gaining popularity for the construction of self‐assembling architectures. We have recently introduced DCRs that exchange alcohols and aldehydes to create hemiaminal ethers within tri(2‐picolyl)amine (TPA) ligands, all of which are templated by Zn II . To expand the scope of this assembly, aromatic imines derived from pyridine‐2‐carboxyaldehyde were explored as dynamic covalent receptors for di(2‐picolyl)amine in the presence of Zn II to create TPA ligands that contain aminal linkages. This represents another metal‐templated in situ multicomponent assembly. The stability of the assembly was successfully modulated through substituent effects, and the equilibrium constants from imines to aminals were correlated by a linear free energy relationship (LFER) with σ + values. Dynamic component exchange was investigated as a means of probing multiple equilibriums quantitatively in the system. Further, the mechanism was analyzed with a qualitative kinetics study. NMR spectra reveal the different extents of two competing pathways for assembly depending upon whether the aromatic amine has electron‐withdrawing or electron‐donating groups on the ring. Finally, mass spectral evidence supports the presence and differing extents of dominance of the two pathways as a function of the substituents.