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  • Title: Mono- and ditopic models of binding of a photochromic chromene annelated with an 18-crown-6 ether with protonated amino acids.
    Author: Paramonov S, Fedorov Y, Lokshin V, Tulyakova E, Vermeersch G, Delbaere S, Fedorova O.
    Journal: Org Biomol Chem; 2012 Jan 21; 10(3):671-82. PubMed ID: 22159499.
    Abstract:
    In this work, the interaction of protonated amino acids with a chromene bearing a fused 18-crown-6 ether moiety was studied by UV-vis and NMR spectroscopy. Initial closed forms of the chromene form monotopic 1 : 1 complexes, the ammonium group being localized inside the crown ether cavity. UV-irradiation leads to transformation of the ring-closed species into the ring-opened form. Depending on the amino acid length, either ditopic or monotopic 1 : 1 complexes are formed. Such complexes are stabilized by the additional H-bonding between the carboxylic group of the acid and the carbonyl oxygen atom of the ring-opened form. Cessation of the irradiation results in ring-closure to the chromene with concomitant change of the complexation mode.
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