Influence of fused aromatic ring on the stability of charge transfer complex between iodine and some five membered heterocyclic molecules through ultrasonic and spectral studies V. Ulagendran, P. Balu, V. Kannappan, R. Kumar, S. Jayakumar Journal of Molecular Structure, 2017 The charge transfer (CT) interaction between two fused heterocyclic compounds with basic pyrrole group as donors, viz., indole (IND) and carbazole (CAR), and iodine (acceptor) in DMSO medium is investigated by ultrasonic and UV–visible spectral methods at 303 K. The formation of CT complex in these systems is established from the trend in acoustical and excess thermo acoustical properties with molar concentration. The frequency acoustic spectra (FAS) is also carried out on these two systems for two fixed concentrations 0.002 M and 0.02 M, and in the frequency range 1 MHz-10 MHz to justify the frequency chosen for ultrasonic study. The absorption coefficient values in solution are computed and discussed. The formation constants of these complexes are determined using Kannappan equation in ultrasonic method. The formation of 1:1 complexes between iodine and IND, CAR was established by the theory of Benesi – Hildebrand in the UV–visible spectroscopic method. The stability constants of the CT complexes determined by spectroscopic and ultrasonic methods show a similar trend. These values also indicate that the presence of fused aromatic ring influences significantly when compared with K values of similar CT complexes of parent five membered heterocyclic compound (pyrrole) reported by us earlier.
Structural analysis and investigation of molecular properties of Cefpodoxime acid, a third generation antibiotic S. Suganthi, P. Balu, V. Sathyanarayanamoorthi, V. Kannappan, M.G. Mohamed Kamil, R. Kumar Journal of Molecular Structure, 2016 Extensive quantum mechanical studies are carried out on Cefpodoxime acid (CA), a new generation drug by Hartree–Fock (HF) and B3LYP methods to understand the structural and spectral characteristics of the molecule. The most stable geometry of the molecule was optimized and the bond parameters were reported. The spectroscopic properties of this pharmaceutically important compound were investigated by FT-IR, FT-Raman, UV and 1 H NMR techniques. The scaled vibrational frequencies of CA in the ground state are calculated by HF and B3LYP methods with 6–311++G (d, p) basis set and compared with the observed FT-IR and FT-Raman spectra. The vibrational spectral analysis indicates the presence of two intra molecular hydrogen bonds in the molecule which is supported by theoretical study. 1 H NMR chemical shifts ( δ ) were calculated for the CA molecule and compared with the experimental values. The theoretical electronic absorption spectral data in water and ethanol solvents were computed by TD-DFT method. UV–Vis absorption spectra of CA are recorded in these two solvents and compared with theoretical spectra. The spectral data and natural bond orbital (NBO) analysis confirm the occurrence of intra molecular interactions in CA. The electronic distribution, in conjunction with electrophilicity index of CA was used to establish the active site and type of interaction between CA and beta lactamases. Mulliken population analysis on atomic charges is also carried out and thermodynamic properties of the title compound are calculated.
Functionalization of N 2 to NH 3 via direct N ≡ N bond cleavage using M(III)(NMe 2 ) 3 (M=W/Mo): A theoretical study SAMBATH BASKARAN, PERUMAL BALU, CHINNAPPAN SIVASANKAR Journal of Chemical Sciences, 2015 Atmospheric N2 can be cleaved directly to yield metal-nitride (before proceeding to the functionalization of Nα of coordinated N2) and subsequently functionalized to ammonia using M(III)(NMe2)3 (M = W/Mo) as a catalyst, and suitable proton and electron sources. The calculated energies of thermodynamic and kinetic states of the various intermediates and transition states in the reaction coordinate to yield ammonia confirmed the viability of the proposed reaction pathway. Rationale of different pathways have been examined and discussed in detail. Changes in the structural features of the catalyst and some important intermediates and transition states have also been examined. Graphical AbstractN2 can be cleaved directly to form nitride complex and subsequently can be converted to ammonia in the presence of protons and electrons using M(III)(NMe2)3 (M = Mo/W) in a homogeneous solution under normal experimental conditions. The proposed pathway seems to be feasible based on the calculated thermodynamic and kinetic barriers.
Determination of thermodynamic properties for protonation equilibrium between isomeric cresols and N,N-dimethylaniline in n-hexane medium R. Rajesh, R. Raj Muhamed, P. Balu, V. Kannappan, R. Kumar Journal of Molecular Liquids, 2015 The formation of hydrogen bonded complexes of o -cresol (OC), m -cresol (MC) and p -cresol (PC) with N,N -dimethylaniline (DMA) in n -hexane solutions is investigated by ultrasonic velocity, density and dynamic viscosity measurements in the equimolar concentration of solutes ([cresol] = [DMA]) ranging from 0.05 to 0.22 mol kg − 1 at 293 K, 298 K, 303 K and 308 K and at atmospheric pressure. The variations in the acoustical and excess acoustical parameters with concentration in the three ternary systems establish the existence of strong solute–solute interactions, probably the formation of hydrogen bonded salts between tertiary amine and cresols. The formation constants (K) of the protonated species are determined using Kannappan equation. It is observed that the formation constant is influenced by the structure of cresol. K values are correlated with the molecular properties of cresols computed by B3LYP method. Thermodynamic parameters such as ΔG, ΔH and ΔS for the three equilibria are determined.
A possibility of functionalizing the dinitrogen in a Chatt complex by H2: Density functional studies Perumal Balu, Sambath Baskaran, Venu Kannappan, Chinnappan Sivasankar Polyhedron, 2012 DFT calculations have been performed to explore the possibility of functionalizing the coordinated N 2 in a Chatt type complex by H 2 , using some suitable organic co-catalysts in a homogeneous fashion. The calculated thermodynamic barriers further revealed that there is the possibility to produce ammonia by the reaction of a Chatt type complex with H 2 in different organic solvents. The electronic features of the various intermediates have also been analyzed.
Hydrogenation of dinitrogen to ammonia in [WF(PH2(CH 2)2PH2)2N2] using H 2: Insights from DFT calculations Perumal Balu, Sambath Baskaran, Venu Kannappan, Chinnappan Sivasankar New Journal of Chemistry, 2012 A new methodology has been proposed to reduce the molecular dinitrogen to ammonia in [WF(PH2(CH2)2PH2)N2] (1) and tested for thermodynamic feasibility by DFT calculations in three different solvents. The calculated barriers for 1 revealed that N2 can be reduced by H2 in organic solvents.
