G RAJARAJAN - Academia.edu (original) (raw)
Papers by G RAJARAJAN
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2015
, electronic structure investigation of 3-pentyl-2,6-di(furan-2-yl)piperidin-4-one by FT-IR, FT-R... more , electronic structure investigation of 3-pentyl-2,6-di(furan-2-yl)piperidin-4-one by FT-IR, FT-Raman and UV-visible spectral studies and ab initio/DFT calculations
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, Jan 3, 2015
The structural and spectroscopic studies of 3t-pentyl-2r,6c-diphenylpiperidin-4-one semicarbazone... more The structural and spectroscopic studies of 3t-pentyl-2r,6c-diphenylpiperidin-4-one semicarbazone (PDPOSC) were made by adopting B3LYP/HF levels theory using 6-311++G(d,p) basis set. The FT-IR and Raman spectra were recorded in solid phase, the fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. DFT method indicates that B3LYP is superior to HF method for molecular vibrational analysis. UV-vis spectrum of the compound was recorded in different solvents in the region of 200-800nm and the electronic properties such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies were evaluated by time-dependent DFT (TD-DFT) approach. The polarizability and first order hyperpolarizability of the title molecule were calculated and interpreted. The hyperconjugative interaction energy (E((2))) and electron densities of donor (i) and acceptor...
![Research paper thumbnail of ChemInform Abstract: 1H NMR Spectral Study of Some 4-Hydroxy-2,6-diphenylpiperidines and a Systematic Analysis of 1H Chemical Shifts in Some Piperidines and 3,7-Diazabicyclo[3.3.1]nonane Derivatives](https://attachments.academia-assets.com/92742585/thumbnails/1.jpg)
](ChemInform, 2010
H NMR spectra have been recorded for c(4)-hydroxy-r(2),c(6)-diphenylpiperidine 7a and its t(3)-me... more H NMR spectra have been recorded for c(4)-hydroxy-r(2),c(6)-diphenylpiperidine 7a and its t(3)-methyl, t(3)-ethyl , t(3)-isopropyl, 3,3-dimethyl and t(3), t(5)-dimethyl derivatives 8a-12a and the corresponding axial 4-hydroxy epimers 7b-12b, at 270 MHz. Various 1 H chemical shifts and coupling constants have been determined by analysis of the spectra. The vicinal coupling constants suggest that boat form may make a slight contribution to the equatorial alcohols. The ~bea value for the 5-methylene protons is less in the axial alcohol than in the corresponding equatorial alcohol and in the case of lib this value is negative. The effects of methyl, ethyl, isopropyl and hydroxyl groups on the chemical shifts of ring protons are discussed. Analysis of the reported proton chemical shifts of 9-hydroxy-3,7-diazabicyclo[3 .3.l]nonanes la-4a suggests that the 3,7-diphenyl compounds should exist in boat-chair conformation.
Arabian Journal of Chemistry, 2016
Two chalcones namely, 1,5-bis(4-hydroxy-3-methoxyphenyl)pentan-1,4-dien-3-one (BHMPD) and 2,5-bis... more Two chalcones namely, 1,5-bis(4-hydroxy-3-methoxyphenyl)pentan-1,4-dien-3-one (BHMPD) and 2,5-bis(4-hydroxy-3-methoxybenzylidene)cyclopentanone (BHMBC) have been synthesised and characterized by microanalysis, FT-IR, mass spectra and NMR (1 H and 13 C) techniques. The thermal decomposition of these compounds was studied by TGA and DTA under dynamic nitrogen atmosphere at different heating rates of 10, 15 and 20 K min À1. The kinetic parameters were calculated using model-fitting (Coats-Redfern, CR) and model-free methods (Friedman, Kissinger-Akahira-Sunose, KAS and Flynn-Wall-Ozawa, FWO). The decomposition process of BHMPD and BHMBC followed a single step mechanism as evidenced from the data. Existence of compensation effect was noticed for the decomposition of these compounds. Invariant kinetic parameters are consistent with the average values obtained by Friedman and KAS isoconversional method in both compounds.
Journal of the Serbian Chemical Society, 2009
The kinetics of oxidation of a number of meta- and para-substituted N,?-diphenylnitrones (nitrone... more The kinetics of oxidation of a number of meta- and para-substituted N,?-diphenylnitrones (nitrone) by dichloramine-T (DCT) was investigated in the presence of alkali in aqueous acetonitrile medium. The order with respect to DCT was one and to OH- an inverse fractional order. The reaction was first order with respect to nitrone. Both electron releasing and withdrawing substituents suppress the reaction rate. The observed rate constant for the substituents were plotted against the Hammett constant, ?, and a non-linear concave downward curve was obtained. The electron withdrawing substituents fall on one side of the curve, having a negative ? value and the electron releasing substituents fall on the other side, with a positive ? value. A mechanism is proposed and the derived rate law is in conformity with the observed results.
Acta Crystallographica Section E Structure Reports Online, 2007
In the title molecule, C 19 H 23 NO, the piperidine ring adopts a chair conformation. The two phe... more In the title molecule, C 19 H 23 NO, the piperidine ring adopts a chair conformation. The two phenyl rings, and the hydroxy and ethyl groups attached to the piperidine ring, have equatorial orientations. The dihedral angle between the two phenyl rings is 54.5 (1). The hydroxy and amino H atoms are each disordered over two positions, with approximately equal site occupancies. Intermolecular O-HÁ Á ÁO, O-HÁ Á ÁN and N-HÁ Á ÁO hydrogen bonds contribute to the stability of the crystal packing. Related literature The conformation of the title molecule was established by 1 H and 13 C NMR spectroscopy by Manimekalai & Rajarajan (1996). Pandiarajan et al. (2000) and Balamurugan et al. (2006, 2007) have reported the crystal structures of di-2-furylpiperidin-4-one derivatives, where the piperidine ring adopts chair and twist-boat conformations, respectively. Experimental Crystal data C 19 H 23 NO M r = 281.38 Monoclinic, P2 1 =c a = 11.6611 (3) Å b = 12.4948 (4) Å c = 12.0089 (3) Å = 117.308 (1) V = 1554.73 (7) Å 3 Z = 4 Mo K radiation = 0.07 mm À1 T = 160 (1) K 0.25 Â 0.23 Â 0.08 mm Data collection Nonius KappaCCD area-detector diffractometer Absorption correction: none 42996 measured reflections 4522 independent reflections 3412 reflections with I > 2(I) R int = 0.090 Refinement R[F 2 > 2(F 2)] = 0.075 wR(F 2) = 0.193 S = 1.13 4522 reflections 205 parameters 4 restraints Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: CV2239).
Acta Crystallographica Section E Structure Reports Online, 2009
International Journal of Advanced Chemistry, 2017
The molecular structure and conformational aspects of 3t-pentyl-2r,6c-di(naphthalen-1-yl)piperidi... more The molecular structure and conformational aspects of 3t-pentyl-2r,6c-di(naphthalen-1-yl)piperidin-4-one oxime (3-PDNPO) were studied by using B3LYP level with 6-31G(d,p) p basis set. The optimized geometrical parameters are in agreement with analogue available single XRD data. The optimized parameters showed that the piperidin-4-one ring adopts chair conformation.The FT- IR and FT-Raman spectra were recorded within the region 4000-400 cm-1 and 4000-10 cm-1, respectively. It was found by experimental wavenumbers and DFT wavenumbers were in good agreement. Electronic properties are investigated using TD-DFT/B3LYP method using 6-31G (d,p) basis set and compared with experimental UV-visible spectra. Additionally, the ΔE gap investigated three phases follows the order of CHCl3…
Journal of King Saud University - Science, 2012
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2015
, electronic structure investigation of 3-pentyl-2,6-di(furan-2-yl)piperidin-4-one by FT-IR, FT-R... more , electronic structure investigation of 3-pentyl-2,6-di(furan-2-yl)piperidin-4-one by FT-IR, FT-Raman and UV-visible spectral studies and ab initio/DFT calculations
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, Jan 3, 2015
The structural and spectroscopic studies of 3t-pentyl-2r,6c-diphenylpiperidin-4-one semicarbazone... more The structural and spectroscopic studies of 3t-pentyl-2r,6c-diphenylpiperidin-4-one semicarbazone (PDPOSC) were made by adopting B3LYP/HF levels theory using 6-311++G(d,p) basis set. The FT-IR and Raman spectra were recorded in solid phase, the fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. DFT method indicates that B3LYP is superior to HF method for molecular vibrational analysis. UV-vis spectrum of the compound was recorded in different solvents in the region of 200-800nm and the electronic properties such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies were evaluated by time-dependent DFT (TD-DFT) approach. The polarizability and first order hyperpolarizability of the title molecule were calculated and interpreted. The hyperconjugative interaction energy (E((2))) and electron densities of donor (i) and acceptor...
ChemInform, 2010
H NMR spectra have been recorded for c(4)-hydroxy-r(2),c(6)-diphenylpiperidine 7a and its t(3)-me... more H NMR spectra have been recorded for c(4)-hydroxy-r(2),c(6)-diphenylpiperidine 7a and its t(3)-methyl, t(3)-ethyl , t(3)-isopropyl, 3,3-dimethyl and t(3), t(5)-dimethyl derivatives 8a-12a and the corresponding axial 4-hydroxy epimers 7b-12b, at 270 MHz. Various 1 H chemical shifts and coupling constants have been determined by analysis of the spectra. The vicinal coupling constants suggest that boat form may make a slight contribution to the equatorial alcohols. The ~bea value for the 5-methylene protons is less in the axial alcohol than in the corresponding equatorial alcohol and in the case of lib this value is negative. The effects of methyl, ethyl, isopropyl and hydroxyl groups on the chemical shifts of ring protons are discussed. Analysis of the reported proton chemical shifts of 9-hydroxy-3,7-diazabicyclo[3 .3.l]nonanes la-4a suggests that the 3,7-diphenyl compounds should exist in boat-chair conformation.
Arabian Journal of Chemistry, 2016
Two chalcones namely, 1,5-bis(4-hydroxy-3-methoxyphenyl)pentan-1,4-dien-3-one (BHMPD) and 2,5-bis... more Two chalcones namely, 1,5-bis(4-hydroxy-3-methoxyphenyl)pentan-1,4-dien-3-one (BHMPD) and 2,5-bis(4-hydroxy-3-methoxybenzylidene)cyclopentanone (BHMBC) have been synthesised and characterized by microanalysis, FT-IR, mass spectra and NMR (1 H and 13 C) techniques. The thermal decomposition of these compounds was studied by TGA and DTA under dynamic nitrogen atmosphere at different heating rates of 10, 15 and 20 K min À1. The kinetic parameters were calculated using model-fitting (Coats-Redfern, CR) and model-free methods (Friedman, Kissinger-Akahira-Sunose, KAS and Flynn-Wall-Ozawa, FWO). The decomposition process of BHMPD and BHMBC followed a single step mechanism as evidenced from the data. Existence of compensation effect was noticed for the decomposition of these compounds. Invariant kinetic parameters are consistent with the average values obtained by Friedman and KAS isoconversional method in both compounds.
Journal of the Serbian Chemical Society, 2009
The kinetics of oxidation of a number of meta- and para-substituted N,?-diphenylnitrones (nitrone... more The kinetics of oxidation of a number of meta- and para-substituted N,?-diphenylnitrones (nitrone) by dichloramine-T (DCT) was investigated in the presence of alkali in aqueous acetonitrile medium. The order with respect to DCT was one and to OH- an inverse fractional order. The reaction was first order with respect to nitrone. Both electron releasing and withdrawing substituents suppress the reaction rate. The observed rate constant for the substituents were plotted against the Hammett constant, ?, and a non-linear concave downward curve was obtained. The electron withdrawing substituents fall on one side of the curve, having a negative ? value and the electron releasing substituents fall on the other side, with a positive ? value. A mechanism is proposed and the derived rate law is in conformity with the observed results.
Acta Crystallographica Section E Structure Reports Online, 2007
In the title molecule, C 19 H 23 NO, the piperidine ring adopts a chair conformation. The two phe... more In the title molecule, C 19 H 23 NO, the piperidine ring adopts a chair conformation. The two phenyl rings, and the hydroxy and ethyl groups attached to the piperidine ring, have equatorial orientations. The dihedral angle between the two phenyl rings is 54.5 (1). The hydroxy and amino H atoms are each disordered over two positions, with approximately equal site occupancies. Intermolecular O-HÁ Á ÁO, O-HÁ Á ÁN and N-HÁ Á ÁO hydrogen bonds contribute to the stability of the crystal packing. Related literature The conformation of the title molecule was established by 1 H and 13 C NMR spectroscopy by Manimekalai & Rajarajan (1996). Pandiarajan et al. (2000) and Balamurugan et al. (2006, 2007) have reported the crystal structures of di-2-furylpiperidin-4-one derivatives, where the piperidine ring adopts chair and twist-boat conformations, respectively. Experimental Crystal data C 19 H 23 NO M r = 281.38 Monoclinic, P2 1 =c a = 11.6611 (3) Å b = 12.4948 (4) Å c = 12.0089 (3) Å = 117.308 (1) V = 1554.73 (7) Å 3 Z = 4 Mo K radiation = 0.07 mm À1 T = 160 (1) K 0.25 Â 0.23 Â 0.08 mm Data collection Nonius KappaCCD area-detector diffractometer Absorption correction: none 42996 measured reflections 4522 independent reflections 3412 reflections with I > 2(I) R int = 0.090 Refinement R[F 2 > 2(F 2)] = 0.075 wR(F 2) = 0.193 S = 1.13 4522 reflections 205 parameters 4 restraints Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: CV2239).
Acta Crystallographica Section E Structure Reports Online, 2009
International Journal of Advanced Chemistry, 2017
The molecular structure and conformational aspects of 3t-pentyl-2r,6c-di(naphthalen-1-yl)piperidi... more The molecular structure and conformational aspects of 3t-pentyl-2r,6c-di(naphthalen-1-yl)piperidin-4-one oxime (3-PDNPO) were studied by using B3LYP level with 6-31G(d,p) p basis set. The optimized geometrical parameters are in agreement with analogue available single XRD data. The optimized parameters showed that the piperidin-4-one ring adopts chair conformation.The FT- IR and FT-Raman spectra were recorded within the region 4000-400 cm-1 and 4000-10 cm-1, respectively. It was found by experimental wavenumbers and DFT wavenumbers were in good agreement. Electronic properties are investigated using TD-DFT/B3LYP method using 6-31G (d,p) basis set and compared with experimental UV-visible spectra. Additionally, the ΔE gap investigated three phases follows the order of CHCl3…
Journal of King Saud University - Science, 2012