Spectrophotometric and computational studies of CT complexes of heterocyclic non-steroidal anti-inflammatory drugs with iodine as σ – Acceptor

Abstract

Abstract Understanding the charge transfer process between bioactive molecules and inorganic or organic molecules is significant as this interaction can be used to interpret the bioactive molecules–receptor interactions. An exhaustive literature survey on the heterocyclic non-steroidal anti-inflammatory drugs (HNSAID), revealed that analysis using iodine as analytical reagent has not been reported. Accordingly, spectrophotometric method has been developed for the determination of HSNAID using iodine (I2) as σ – acceptor. This method is based on the element of decrease in intensity of colour produced by the reaction of HSNAID with I2 in ethylene dichloride at room temperature. The spectrophotometric measurement has been made at absorption maximum 362 nm. All formed complexes exhibit well resolved charge transfer bands in this region where neither donor nor acceptor has appreciable absorption at 362 nm. The binding ratio of complexation has been determined to be 1:1 for the iodine with the HSNAID. The spectroscopic parameters like association constant (K), extinction coefficient (emax), ionization potential (IP), energy of the charge transfer complex (ECT), resonance energy (RN), dissociation energy (W) and standard Gibbs free energy (ΔG0) have been computed. Based upon spectrophotometric method the association constant of HSNAID with I2 is found to be in the order of Indometacin > Ketorolac. In order to support experimental study, computational study has been carried out using GAMESS computations as a package of chem Bio 3D ultra 12.0. A good consistency between experimental and computational results has been found.