Anion Recognition by a Pincer-Type Host Constructed from Two Polyamide Macrocyclic Frameworks Jointed by a Photo-Addressable Azobenzene Switch
A sterically crowded light-responsive host was synthetized with a 93% yield by applying a post-functionalization protocol utilizing the double amidation of 4,4'-azodibenzoyl dichloride with a readily available 26-membered macrocyclic amine. X-ray structures of two hydrates of - demonstrate a ve...
Saved in:
Published in | Materials Vol. 15; no. 2; p. 692 |
---|---|
Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
Switzerland
MDPI AG
17.01.2022
MDPI |
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | A sterically crowded light-responsive host
was synthetized with a 93% yield by applying a post-functionalization protocol utilizing the double amidation of 4,4'-azodibenzoyl dichloride with a readily available 26-membered macrocyclic amine. X-ray structures of two hydrates of
-
demonstrate a very different alignment of the azobenzene linkage, which is involved in
-shape or parallel-displaced π⋯π stacking interactions with the pyridine-2,6-dicarboxamide moieties from the macrocyclic backbone. Despite the rigidity of the macrocyclic framework, which generates a large steric hindrance around the azobenzene chromophore, the host
retains the ability to undergo a reversible
⟷
isomerization upon irradiation with UVA (368 nm) and blue (410 nm) light. Moreover, thermal
→
back-isomerization (ΔG
= 106.5 kJ∙mol
,
= 141 h) is markedly slowed down as compared to the non-macrocyclic analog.
H NMR titration experiments in DMSO-
/0.5% water solution reveal that
-
exhibits a strong preference for dihydrogenphosphate (H
PO
) over other anions (Cl
, MeCO
, and PhCO
), whereas the photogenerated metastable
-
shows lower affinity for the H
PO
anion. |
---|---|
Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 1996-1944 1996-1944 |
DOI: | 10.3390/ma15020692 |