title: Quenching of pyrene fluorescence by calix[4]arene and calix[4]resorcinarenes.
abstract: Interactions involving calixarene and its derivatives are of major importance due to their widespread applications as unique hosts. Fluorescence from a common probe pyrene is used to study interactions involving calix[4]resorcinarene [1a] and its tetra-morpholine derivative [1b] in 1 M aqueous NaOH. These compounds efficiently quench the pyrene fluorescence. A comparison with the fluorescence quenching behavior of N-methylmorpholine clearly indicates the presence of long-range interactions involving 1a and 1b; the interactions are specific to the calixarene molecular framework. This is not the case for a tetra-nitro-substituted calix[4]arene [2b], an electron/charge acceptor quencher, as p-nitrophenol also shows similar interactions with pyrene. Effectiveness of cesium as the quencher of pyrene fluorescence is reduced in the presence of electron/charge donating 1b; fluorescence enhancement is observed upon addition of cesium as the concentration of 1b is increased in the solution. The role of calixarene framework in interactions involving such compounds is established.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India. sipandey@chemistry.iitd.ac.in
authors.forename: Shubha
authors.initials: S
authors.lastname: Pandey
authors.forename: Maroof
authors.initials: M
authors.lastname: Ali
authors.forename: Anjali
authors.initials: A
authors.lastname: Bishnoi
authors.forename: Amir
authors.initials: A
authors.lastname: Azam
authors.forename: Siddharth
authors.initials: S
authors.lastname: Pandey
authors.forename: H M
authors.initials: HM
authors.lastname: Chawla