Sensing ability of fluorescence based chemosensor: Indole7carboxaldehyde (I7C) for environmentally hazardous metal ions (Xn+ = Zn2+, Pb2+, Co2+, Ni2+, Cr3+) has been investigated. Based on excited state proton transfer (ESPT) phenomenon, the sensing capability of I7C is verified experimentally (UVVis, FTIR, NMR) and theoretically (DFT, TDDFT) in aqueous media. Chemical hardness (), electrophilicity () and electronic chemical potentials () confirm the selective reactivity of I7C (Nc and Nt conformers) in the presence of metal ions by the formation of (1:1) metal ion: I7C complex (MX, MX*). MX, MX* are found to display excellent sensing capability for Zn2+ and Pb2+ ions. “TurnOn” response for Zn2+ is observed through the appearance of a new enhanced fluorescence at ~ 430 nm. By strong blue emission I7C establishes its strong candidature as “blue emitter”. “TurnOff” response is observed for Pb2+ through the quenching of the existing fluorescence peak. Keyword: chemosensor, fluorescence, chemical reactivity, Zn2+ ion, ESPT. *Corresponding author, Fax: +91 120 2400986 E-mail: papia.chowdhury@jiit.ac.in 1. Introduction: Sensing of environmentally hazardous metal ions is one of the major challenges to the sustainable development [1] of society now days since metal ions play an important role in a wide range of biological, chemical and environmental processes. With the increase in terrorist activities now it has become an absolute necessity to design accurate, reliable, realtime metal sensors for the detection of explosives, landmines and warfare chemicals that use metal ions as a main component [2]. Especially sensors which induce changes in colour appear to be particularly attractive due to easy detect... ... middle of paper ... ... , (1) where εLUMO and εHOMO are the LUMO and HOMO energies, respectively. represents the escaping tendency of an electron from an equilibrium. Greater value of represents more reactivity of the system as: , (2) Global electrophilicity index () measures the stabilization energy of specific complex. can be calculated as [33] . (3) To establish a correlation between the components of the complexation formed, Binding Energy for complexation can be calculated as (4)
...mputer program’s values. This is due to the fact that the computer program has values that follow specific criteria, and under real circumstance the behavior of a molecule doesn’t always follow this assumed path. The error determined by the error analysis for B which effected following values was of some concern, however this could be alleviated by choosing a better fitting equation for the data with regards to both sets of data. With this in mind the outcome of the experiment is satisfactory as far as calculated values and gained experience is concerned.
A spectrum is a group of light wavelengths that are ordered in relation to their wavelength length. The electromagnetic spectrum consists radio waves, microwaves, infrared, visible, ultraviolet, X-rays and gamma rays. (1)Specifically, this lab looks at the visible light part of the spectrum because one of the colors in the visible light spectrum is shine through the sample. The visible light spectrum consists of colors of red, orange, yellow, green, blue, indigo, and violet. The color chosen to be shine through the sample is affected by the color of sample when mixed with the indicator Ammonium Vanadomolybdate (AMV). The color on the color wheel that is opposite of the solution’s color is the color that is shined through the
We thank the University of Oklahoma and the chemistry faculty for providing the space, instructions, and equipment for the development of this report and experiment.
Mckervey, M. A.; Tuladhar, S. M.; Twohig, M. F. J. Chem. Soc., Chem. Comm., 1984, 129.
From the equation above, A is absorbance of the solution in equilibrium, ε is the molar absurdity of the molecule and l is the cuvette width; the length of which light goes through the cuvette.
middle of paper ... ... Chemistry, the Central Science 11th Edition (p. 1072). (2009). The 'Standard' of the 'Standard'. 25.
Varying the n value carries out the experiment. Absorbencies of each of the ZLn complexes are obtained. The sum of the concentrations of the metal, Z, and the ligand, L, are kept equal. With the ratio of the ligand to the metal in the solution with the maximum absorbance for the ZLn complex, the value of n can be determined as well as the composition of ZLn.
Thickett, Geoffrey. Chemistry 2: HSC course. N/A ed. Vol. 1. Milton: John Wiley & Sons Australia, 2006. 94-108. 1 vols. Print.
David and John Free. (26 Nov 2006). MadSci Network: Chemistry. Retrieved on March 6, 2011, from http://www.madsci.org/posts/archives/2007-02/1171045656.Ch.r.html
23. S. Alwarappan, S. Boyapalle, A. Kumar, C.-Z. Li and S. Mohapatra, J. Phys. Chem. C, 2012, 116, 6556–6559
Individual atoms can emit and absorb radiation only at particular wavelengths equal to the changes between the energy levels in the atom. The spectrum of a given atom therefore consists of a series of emission or absorption lines. Inner atomic electrons g... ... middle of paper ... ... a sensitive multielement inorganic analyses.
In biochemical reactions, the enzyme, E, combines reversibly with its specific substrate, S, to form a complex ES. One result of this temporary formation is a reduction in the energy required to activate the reaction of the substrate molecule so that P, the products of the reaction are formed. In summary: E+SESE+P. The enzyme is not changed in the reaction and can break down additional substrate molecules (Lab Bench).
According to (Biesen) , In a complexometric titration a coordination covalent bond is formed via the ability of most metal ions to receive unshared pairs of electrons from a anion or molecule. Furthermore, a ligand: which is a molecule that contain a lone pair of electrons and can therefore form a bond with a complex ion or metal ion. Therefore a ligand determines the metal ion concentration. [2] Therefore according to (Hussain, 2007), the maximum amount of ligands that can take part in a titration are known as Werner’s Number and allow for complex formation.[13]
Plontke, R. (2003, March 13). Chemnitz UT. TU Chemnitz: - Technische Universität Chemnitz. Retrieved April 1, 2014, from http://www.tu-chemnitz.de/en/
Ionic compounds, when in the solid state, can be described as ionic lattices whose shapes are dictated by the need to place oppositely charged ions close to each other and similarly charged ions as far apart as possible. Though there is some structural diversity in ionic compounds, covalent compounds present us with a world of structural possibilities. From simple linear molecules like H2 to complex chains of atoms like butane (CH3CH2CH2CH3), covalent molecules can take on many shapes. To help decide which shape a polyatomic molecule might prefer we will use Valence Shell Electron Pair Repulsion theory (VSEPR). VSEPR states that electrons like to stay as far away from one another as possible to provide the lowest energy (i.e. most stable) structure for any bonding arrangement. In this way, VSEPR is a powerful tool for predicting the geometries of covalent molecules.