title: Recognition-mediated light-up of thiazole orange with cucurbit[8]uril: exchange and release by chemical stimuli.
abstract: This article reports a convenient supramolecular strategy to construct fluorescent photoswitchable molecular assemblies between a macrocyclic host, cucurbit[8]uril (CB8), and a fluorogenic dye, thiazole orange (TO). The interaction mechanism and the stable stoichiometric host-guest arrangements have been claimed on the basis of the optical absorption, steady-state and time-resolved fluorescence lifetime and anisotropy measurements, and also the geometry optimization studies. The CB8 recognized TO in its 2:2 stoichiometry exhibited spectacular fluorescence enhancement of the order of 1700 fold, which is the largest directly determined value so far reported for a dye in an organic macrocyclic system. This prospective 2CB8:2TO assembly responded to selected chemical stimuli such as metal ions, adamantylamine, and tryptophan, providing different dissociation mechanisms and demonstrating a controlled exchange and release action desired with such noncovalently linked assemblies. Positively, considering the aqueous solubility and biocompatibility of the host-guest constituents, this methodology can evolve into a general approach to deliver and operate intracellularly functional molecular components under chemical/thermal/optical trigger control, especially for therapeutic applications.
authors.affiliation: Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Mumbai, India. jyotim@barc.gov.in
authors.forename: Jyotirmayee
authors.initials: J
authors.lastname: Mohanty
authors.forename: Neha
authors.initials: N
authors.lastname: Thakur
authors.forename: Sharmistha Dutta
authors.initials: SD
authors.lastname: Choudhury
authors.forename: Nilotpal
authors.initials: N
authors.lastname: Barooah
authors.forename: Haridas
authors.initials: H
authors.lastname: Pal
authors.forename: Achikanath C
authors.initials: AC
authors.lastname: Bhasikuttan
mesh_terms: D000547:Amantadine / Q000737:chemistry; D052160:Benzothiazoles / Q000737:chemistry*; D001952:Bridged-Ring Compounds / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D008670:Metals / Q000737:chemistry; D011804:Quinolines / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D014364:Tryptophan / Q000737:chemistry; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils
chemical_list: D000547:Amantadine; D052160:Benzothiazoles; D001952:Bridged-Ring Compounds; D007093:Imidazoles; D008670:Metals; D011804:Quinolines; D014364:Tryptophan; C507198:cucurbit(8)uril; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils; C051000:thiazole orange