title: Triazole-linked-thiophene conjugate of calix[4]arene: its selective recognition of Zn2+ and as biomimetic model in supporting the events of the metal detoxification and oxidative stress involving metallothionein.
abstract: Supramolecular calix[4]arene conjugate (L) has been developed as a sensitive and selective sensor for Zn(2+) in HEPES buffer among the 12 metal ion by using fluorescence, absorption and ESI MS and also by visual fluorescent color. The structural, electronic, and emission properties of the calix[4]arene conjugates L and its zinc complex, [ZnL], have been demonstrated using ab initio density functional theory (DFT) combined with time-dependent density functional theory (TDDFT) calculations. The TDDFT calculations reveal the switch on fluorescence behavior of L is mainly due to the utilization of the lone pair of electrons on imine moiety by the Zn(2+). The resultant fluorescent complex, [ZnL], has been used as a secondary sensing chemo-ensemble for the detection of -SH containing molecules by removing Zn(2+) from [ZnL] and forming {Cys/DTT·Zn} adducts as equivalent to those present in metallothioneins. The displacement followed by the release of the coordinated zinc from its Cys/DTT complex by heavy metal ion (viz. Cd(2+) and Hg(2+)), as in the metal detoxification process or by ROS (such as H(2)O(2)) as in the oxidative stress, has been well demonstrated using the conjugate L through the fluorescence intensity retrieval wherein the fluorescence intensity is the same as that observed with [ZnL], which in turn mimics the zinc sensing element (MTF) in biology.
authors: Bioinorganic Laboratory & Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India.
authors: Rakesh Kumar
authors: RK
authors: Pathak
authors: Vijaya Kumar
authors: VK
authors: Hinge
authors: Milon
authors: M
authors: Mondal
authors: Chebrolu Pulla
authors: CP
authors: Rao
mesh_terms: D032701:Biomimetics / Q000379:methods*; D002021:Buffers; D047250:Calixarenes / Q000138:chemical synthesis* / Q000378:metabolism; D018360:Crystallography, X-Ray; D004583:Electrons; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D007097:Imines / Q000737:chemistry; D008658:Inactivation, Metabolic; D009682:Magnetic Resonance Spectroscopy; D008668:Metallothionein / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D018384:Oxidative Stress; D011789:Quantum Theory; D013050:Spectrometry, Fluorescence; D021241:Spectrometry, Mass, Electrospray Ionization; D013816:Thermodynamics; D013876:Thiophenes / Q000737:chemistry*; D014230:Triazoles / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry / Q000378:metabolism*
chemical_list: D002021:Buffers; D007097:Imines; D013876:Thiophenes; D014230:Triazoles; D047250:Calixarenes; D008668:Metallothionein; D006861:Hydrogen Peroxide; D015032:Zinc