Light-Driven Photoconversion of Squaramides with Implications in Anion Transport

Abstract

Simple, clean and fast photoconversion of anilinederived squaramides was achieved by flashlight illumination. UV irradiation enabled the photochemical squaramide ring-opening to generate 1,2-bisketenes, which DMSO trapped as the nucleophilic oxidant. The only photoproducts isolated were 3,4-arylamino maleic anhydrides, which present conformational preferences very different from those of their parent squaramides. Similar photoconversion was achieved in MeOH. The UV-mediated time-dependent anion transport inhibition was demonstrated, establishing a new approach for modulating the transport abilities of AD-squaramides.

Squaramide-based receptors in anion supramolecular chemistry: insights into anion binding, sensing, transport and extraction

“…Another example of transport modulation by light was recently reported by Costa, Rotger and co-workers. 106 As shown in Fig. 47(A), upon irradiation at 365 nm, squaramide 110 was photo-converted to maleic anhydride 110a which is not able to act as chloride transporter as demonstrated by the lucigenin assay.…”

Phototriggered Butenolide Formation from a Cyclobutenedione and an Acidic Nucleophile

“…Carbon and nitrogen substituted bisketenes are not stable and rapidly revert to cyclobutenedione, while silyl substituted bisketenes are relatively stable and isolable at room temperature . The produced bisketenes can react with various chemical species such as alcohol, − amine, alkene, imine, and aldehyde (Scheme a). In the reactions involving bisketene, various products including butenolide derivatives can be produced.…”