Repository logo
 

Influence of non-covalent preorganization on supramolecular effective molarities.


Change log

Authors

Sun, Hongmei 
Navarro, Cristina 
Hunter, Christopher A 

Abstract

A family of closely related zinc porphyrin-pyridine complexes were used to examine the influence of linker preorganization on supramolecular effective molarities for formation of intramolecular H-bonds. Each pyridine ligand was equipped with a side-chain containing two H-bond acceptors, one on the end of the chain (terminal) and one in the middle of the chain (linker). These H-bond acceptors make intramolecular interactions with phenol H-bond donors on the porphyrin periphery. Two different H-bonding acceptors were used as linker groups in order to construct frameworks with significantly different degrees of preorganization: ester linkers populate the H-bonded state 60-70% of the time, whereas amide linkers populate the H-bonded state 90-100% of the time. Thus the amide linkers provide a significantly more preorganised ligand framework than the ester linkers. Effective molarities (EM) for intramolecular H-bonds between the terminal H-bond acceptor groups on the ligands (esters and amides) and the porphyrin phenol groups were quantified using 32 chemical double mutant cycles. The values of EM for interactions with the terminal H-bond acceptors are independent of the nature of the linker H-bond acceptor (weakly bonded ester or strongly bonded amide), which indicates that preorganization of the linker has no effect on chelate cooperativity in these systems.

Description

Keywords

0306 Physical Chemistry (incl. Structural)

Journal Title

Org Biomol Chem

Conference Name

Journal ISSN

1477-0520
1477-0539

Volume Title

13

Publisher

Royal Society of Chemistry (RSC)
Sponsorship
We thank the EPSRC, the China Scholarship Council, and the University of Sheffield for funding.