title: Surfactants induced release of a red emitting dye from the nanocavity of a molecular container: A spectroscopic and calorimetric study.
abstract: Supramolecular interaction of a red emitting dye Nile blue A (NBA) with Cucurbit[7]uril (CB7) in aqueous solution was studied and the release of the dye from the hydrophobic cavity of CB7 was reported. To investigate the supramolecular host-guest complex formation and release of dye, we have used the steady state absorption, fluorescence and time resolved fluorescence emission spectroscopy, (1)H NMR spectroscopy and isothermal titration calorimetry (ITC). The spectral properties of NBA were changed in the presence of CB7. The change in spectral features of NBA in presence of CB7 indicates the formation of supramolecular host-guest complexes. By using the SED equation the diameter of the complex was estimated. The complex formation further affirmed by the (1)H NMR study. Upfield and downfield shifts of the protons of NBA was observed in both the aliphatic and aromatic region. From the ITC measurement, we have drawn up the forces involved for the complexation of NBA with CB7. We have studied the release of NBA from the hydrophobic cavity of CB7 by using ionic, neutral surfactants and ionic liquid with the help of spectroscopic and calorimetric techniques. It is observed that on addition of SDS and ionic liquid (<cmc) ion-pair formation takes place between NBA and surfactant monomer whereas, it was not observed for neutral and cationic surfactant. Above cmc of the surfactants, complex is formed between NBA and micelle.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Patna, Patna 801103, Bihar, India.
authors.forename: Sayeed Ashique
authors.initials: SA
authors.lastname: Ahmed
authors.affiliation: Department of Chemistry, Indian Institute of Technology Patna, Patna 801103, Bihar, India.
authors.forename: Aninda
authors.initials: A
authors.lastname: Chatterjee
authors.affiliation: Department of Chemistry, Indian Institute of Technology Patna, Patna 801103, Bihar, India.
authors.forename: Banibrata
authors.initials: B
authors.lastname: Maity
authors.affiliation: Department of Chemistry, Indian Institute of Technology Patna, Patna 801103, Bihar, India. Electronic address: debabrata@iitp.ac.in.
authors.forename: Debabrata
authors.initials: D
authors.lastname: Seth
mesh_terms: D001952:Bridged-Ring Compounds / Q000737:chemistry; D002151:Calorimetry; D004396:Coloring Agents / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry; D052578:Ionic Liquids / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D049329:Nanostructures / Q000737:chemistry*; D010078:Oxazines / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils
chemical_list: D001952:Bridged-Ring Compounds; D004396:Coloring Agents; D007093:Imidazoles; D052578:Ionic Liquids; D010078:Oxazines; D013501:Surface-Active Agents; D014867:Water; C456276:cucurbit(7)uril; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils; C008619:Nile Blue
keywords: Cucurbit[7]uril; Ionic liquid; Isothermal titration calorimetry; Nile blue A; Release of dye; Supramolecular complex