Journal of Scientific and Technical Research (Sharda University, Noida)

N. Radha ¹, M. Swaminathan ²

Affiliations
1 Department of Chemistry, Alagappa Government Arts College, Karaikudi, Tamil Nadu, IN
2 Nanomaterials Laboratory, International Research Centre, Kalasalingam Univeristy, Krihnankoil, Tamil Nadu, IN

Abstract

Fluorescence quenching of four naphthalenediols [1,5-; 1,7-; 2,7-; and 2,3- Naphthalenediols (NDs)] by inorganic anions [Cl−, Br−, SO₄ ²⁻ SO₃ ²⁻, S₂O₂ ²⁻, CO₃ ²⁻, NO₃ ⁻, and HPO₄ ²⁻] have been studied in 95% (v/v) water -ethanol mixture medium. The quenching was found to be dynamic in all systems. The plots of log k_q values with singlet transition energy (E_s) of the fluorophore and with ECTTS of the quencher are linear indicating the presence of electron transfer quenching mechanism. ΔG_TH values for charge transfer quenching have been determined for naphthalenediols.

Keywords

Fluorescence Quenching, Naphthalenediols, Anionic Quenching, Electron Transfer Mechanism.

Full Text

     

P. Siva Kumar ¹, S. Kothai Nayaki ², M. Swaminathan ²

Affiliations
1 Department of Chemistry, Annamalai University, Annamalainagar, Tamilnadu, IN
2 Chemistry Section, Annamalai University, Annamalainagar, Tamilnadu, IN

Abstract

The absorption and fluorescence spectral properties of 2-amino-4,6-diphenylpyrimidine (ADP) have been investigated in a series of organic solvents of different polarity and in aqueous solutions with Ho/pH/H_ in the range -10 to 17. The largely red shifted fluorescence maximum observed in hydrogen bonding solvents can be attributed to dual intermolecular hydrogen bonding interaction between ADP and the solvents. The correlation between the Stokes shifts and the solvent polarity parameters, is better with ET (30) than with BK values. The low value of correlation coefficient may be due to the presence of both intra-and dual intermolecular hydrogen bonding in polar solvents.The acidity constants for various prototropic reactions in So and S1 states are determined and discussed.

Keywords

2-Amino-4,6-Diphenylpyrimidine, Hydrogen Bonding Interactions, Prototropic Reaction, Solvent Polarity Parameters, Acidity Constant Values.

Full Text