title: Metal-ion-mediated assemblies of thiazole orange with cucurbit[7]uril: a photophysical study.
abstract: The formation of molecular superstructures by metal-ion-mediated noncovalent self-assembly has been demonstrated using the macrocycle, cucurbit[7]uril (CB7), and the dye, thiazole orange (TO), as building blocks. Interestingly, the association of these molecular building blocks can be tuned by the chemical environment, leading to self-assembled structures of different stoichiometries, which is supported by absorption, fluorescence, (1)H NMR, and AFM measurements. Most importantly, the self-assembly process of the CB7/TO/metal ion system is observed to be remarkably different for alkali (Na(+)) and alkaline earth (Ca(2+)) metal ions. Fluorescence enhancement is observed in the presence of Ca(2+) ions, which is attributed to the formation of short dimeric structures composed of two 1:1 CB7-TO complexes. Solution turbidity is detected in the presence of Na(+) ions, which is proposed to be due to the formation of extended structures by the assembly of many 1:1 CB7-TO complexes.
authors: Radiation & Photochemistry Division, Bhabha Atomic Research Centre , Mod. Lab., Mumbai 400085, Maharashtra, India.
authors: Meenakshi N
authors: MN
authors: Shinde
authors: Sharmistha
authors: S
authors: Dutta Choudhury
authors: Nilotpal
authors: N
authors: Barooah
authors: Haridas
authors: H
authors: Pal
authors: Achikanath C
authors: AC
authors: Bhasikuttan
authors: Jyotirmayee
authors: J
authors: Mohanty