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...

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Published inMaterials Vol. 15; no. 2; p. 692
Main Authors Niedbała, Patryk, Ceborska, Magdalena, Mehmet, Mart, Ignacak, Wiktor, Jurczak, Janusz, Dąbrowa, Kajetan
Format Journal Article
LanguageEnglish
Published Switzerland MDPI AG 17.01.2022
MDPI
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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.
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ISSN:1996-1944
1996-1944
DOI:10.3390/ma15020692