title: Lower rim 1,3-di{4-antipyrine}amide conjugate of calix[4]arene: synthesis, characterization, and selective recognition of Hg2+ and its sensitivity toward pyrimidine bases.
abstract: The structurally characterized lower rim 1,3-di{4-antipyrine}amide conjugate of calix[4]arene (L) exhibits high selectivity toward Hg(2+) among other biologically important metal ions, viz., Na(+), K(+), Ca(2+), Mg(2+), Mn(2+), Fe(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+), Pb(2+), and Ag(+) as studied by fluorescence, absorption, and ESI MS. L acts as a sensor for Hg(2+) by switch-off fluorescence and exhibits a lowest detectable concentration of 1.87 ± 0.1 ppm. The complex formed between L and Hg(2+) is found to be 1:1 on the basis of absorption and fluorescence titrations and was confirmed by ESI MS. The coordination features of the mercury complex of L were derived on the basis of DFT computations and found that the Hg(2+) is bound through an N(2)O(2) extending from both the arms to result in a distorted octahedral geometry with two vacant sites. The nanostructural features such as shape and size obtained using AFM and TEM distinguishes L from its Hg(2+) complex and were different from those of the simple mercuric perchlorate. L is also suited to sense pyrimidine bases by fluorescence quenching with a minimum detection limit of 1.15 ± 0.1 ppm in the case of cytosine. The nature of interaction of pyrimidine bases with L has been further studied by DFT computational calculations and found to have interactions through a hydrogen bonding and NH-π interaction between the host and the guest.
authors.affiliation: Bioinorganic Laboratory, Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
authors.forename: Jayaraman
authors.initials: J
authors.lastname: Dessingou
authors.forename: Khatija
authors.initials: K
authors.lastname: Tabbasum
authors.forename: Atanu
authors.initials: A
authors.lastname: Mitra
authors.forename: Vijaya Kumar
authors.initials: VK
authors.lastname: Hinge
authors.forename: Chebrolu P
authors.initials: CP
authors.lastname: Rao
mesh_terms: D000042:Absorption; D000577:Amides / Q000737:chemistry*; D000632:Aminopyrine / Q000031:analogs & derivatives* / Q000737:chemistry; D000983:Antipyrine / Q000737:chemistry*; D047250:Calixarenes / Q000737:chemistry*; D060326:Chemistry Techniques, Synthetic / Q000379:methods*; D008628:Mercury / Q000737:chemistry*; D000432:Methanol / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry; D010636:Phenols / Q000737:chemistry*; D011743:Pyrimidines / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013379:Substrate Specificity
chemical_list: C572388:1,3-di(4-antipyrine)amide; D000577:Amides; D010636:Phenols; D011743:Pyrimidines; C121325:calix(4)arene; D000632:Aminopyrine; D047250:Calixarenes; D008628:Mercury; C030986:pyrimidine; D000983:Antipyrine; D000432:Methanol