Theoretical Study of Metal−Ligand Interaction in Sm(III), Eu(III), and Tb(III) Complexes of Coumarin-3-Carboxylic Acid in the Gas Phase and Solution (original) (raw)
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Chemical Physics, 2006
The binding mode of coumarin-3-carboxylic acid (HCCA) to La(III) is elucidated at experimental and theoretical level. The complexation ability of the deprotonated ligand (CCA À ) to La(III) is studied using elemental analysis, DTA and TGA data as well as FTIR, 1 H NMR and 13 C NMR spectra. The experimental data suggest the complex formula La(CCA) 2 (NO 3 )(H 2 O) 2 . B3LYP, BHLYP, B3P86, B3PW91, PW91P86 and MPW1PW91 functionals are tested for geometry and frequency calculations of the neutral ligand and all of them show bond length deviations bellow 1%. B3LYP/6-31G(d) level combined with large quasi-relativistic effective core potential for lanthanum is selected to describe the molecular, electronic and vibrational structures as well as the conformational behavior of HCCA, CCA À and La-CCA complex. The metal-ligand binding mode is predicted through molecular modeling and energy estimation of different La-CCA structures. The calculated atomic charges and the bonding orbital polarizations point to strong ionic metal-ligand bonding in La-CCA complex and insignificant donor acceptor interaction. Detailed vibrational analysis of HCCA, CCA À and La(C-CA) 2 (NO 3 )(H 2 O) 2 systems based on both calculated and experimental frequencies confirms the suggested metal-ligand binding mode.
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 2011
Novel Ni(II), Co(II), Zn(II) and Mn(II) complexes of coumarin-3-carboxylic acid (HCCA) were studied at experimental and theoretical levels. The complexes were characterised by elemental analyses, FT-IR, (1)H NMR, (13)C NMR and UV-Vis spectroscopy and by magnetic susceptibility measurements. The binding modes of the ligand and the spin states of the metal complexes were established by means of molecular modelling of the complexes studied and calculation of their IR, NMR and absorption spectra at DFT(TDDFT)/B3LYP level. The experimental and calculated data verified high spin Ni(II), Co(II) and Mn(II) complexes and a bidentate binding through the carboxylic oxygen atoms (CCA2). The model calculations predicted pseudo octahedral trans-[M(CCA2)(2)(H(2)O)(2)] structures for the Zn(II), Ni(II) and Co(II) complexes and a binuclear [Mn(2)(CCA2)(4)(H(2)O)(2)] structure. Experimental and calculated (1)H, (13)C NMR, IR and UV-Vis data were used to distinguish the two possible bidentate binding ...
Vibrational Spectroscopy, 2007
New complexes of cerium(III) and neodymium(III) with coumarin-3-carboxylic acid (HCCA) were synthesized and characterized. The elemental, DTA and TGA analyses showed the general formula, Ln(CCA) 2 (NO 3 )(H 2 O) (Ln = Ce, Nd). To suggest the binding mode of HCCA a detail vibrational investigation based on Raman, FTIR and DFT/B3LYP/SVP studies of HCCA, its deprotonated form (CCA À ), KCCA and Ln(CCA) 2 (NO 3 )(H 2 O) species, was performed. Two bidentate binding modes of CCA À to Ln(III) were modeled: (1) through the deprotonated carboxylic and the carbonylic oxygens and (2) through both the carboxylic oxygens. The vibrational analysis and the electronic energy calculations pointed to the first binding as more probable. The calculated vibrational spectra of the Ln(III) complexes with the second type binding (through both carboxylic oxygens) showed inconsistencies with the experimental spectra of the complexes. It was shown further that the direct comparison of the vibrational spectra of HCCA and Ln(III) complexes could be informative only to suggest the binding of CCA À to the Ln(III) ions but it does not give reliable information about the type of the binding mode. The model calculations indicated that the vibrational spectrum of KCCA is a better base for comparison with the Ln(III) complex spectra when it is used for prediction of the CCA À binding mode in the complexes studied. #
Experimental and Theoretical Studies on Biologically Active Lanthanide (III) Complexes
The complexation ability and the binding mode of the ligand coumaiin-3-carboxyIic acid (HCCA) to La(III), Ce(III), Nd(III), Sm(III), Gd(III) and Dy(III) lanthanide ions (Ln(III)) are elucidated at experimental and theoretical level. The complexes were characterized using elemental analysis, DTA and TGA data as well as 'H NMR and "C NMR spectra. FTIR and Raman spectroscopic techniques as well as DFT quantum chemical calculations were used for characterization of the binding mode and the structures of lanthanide(III) complexes of HCCA. The metal-Ugand binding mode is predicted through molecular modeling and energy estimation of different Ln-CCA structures using B3LYP/6-31G(d) method combined with a large quasirelativistic effective core potential for lanthanide ion. The energies obtained predict bidentate coordination of CCA" to Ln(III) ions through the carbonylic oxygen and the carboxylic oxygen. Detailed vibrational analysis of HCCA, CCA" and Ln(III) complexes based on both calculated and experimental frequencies confirms the suggested metal-Iigand binding mode. The natural bonding analysis predicts strongly ionic character of the Ln(III)-CCA bonding in the" complexes studied. With the relatively resistant tumor cell line K-562 we obtained very interesting in-vitro results which are in accordance with our previously published data concerning the activity of lanthanide(III) complexes with other coumarin derivatives.
Inorganic Chemistry Communications, 2020
Herein, [M(HL) 2 (H 2 O) 2 ]NO 3 •2H 2 O (M = Sm (III) /or Eu (III); HL = 4-(2-hydroxy benzylidene acetohyrazide)-7hydroxy coumarin) were synthesized and characterized using several spectroscopic methods. The complexes stoichiometry with molar ratio 2L:1M were confirmed by Job's method. Tridentate ligand (HL) was coordinated to the lanthanide ions Sm(III) or Eu(III) through azomethine nitrogen atom, phenolic oxygen of hydrazide, and ketonic oxygen of the amide group. The photophysical properties of the ligand and its complexes were studied in different organic solvents and their fluorescence quantum yields were determined as well. Strong fluorescence emissions to red shifts of europium complex were observed at 580, 593, 617, 653, 693, 704 nm which were attributed to Eu(III) emission of 5
Acta pharmaceutica (Zagreb, Croatia), 2004
A complex of cerium(III) with 4-methyl-7-hydroxycoumarin was synthesized by mixing water solutions of cerium(III) nitrate and 4-methyl-7-hydroxycoumarin sodium salt in a metal-to-ligand molar ratio of 1:2. The complex was characterized and identified by elemental analysis, conductometry, IR, 1H and 13C NMR-spectroscopy, mass spectral data, DTA and TGA. Thermal analysis of the complex indicated the formation of a compound of the composition CeR2(OH).5H2O, R standing for the ligand. The reaction of cerium(III) with 4-methyl-7-hydroxycoumarin was studied in detail by the spectrophotometric method. The stepwise formation of two complexes, vis., CeR2+ and CeR2+, was established in the pH region studied. The equilibrium constants for 1:1 and 1:2 complexes were determined to be 10.72 and 9.22, respectively.
Acta pharmaceutica (Zagreb, Croatia), 2004
A complex of neodymium(III) with 4-hydroxy-3[1-(4-nitrophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one (acenocoumarol) was synthesized by mixing water solutions of neodymium(III) nitrate and the ligand (metal to ligand molar ratio of 1:3). The complex was characterized and identified by elemental analysis, conductivity, IR, 1H NMR and mass spectral data. DTA and TGA were applied to study the composition of the compound. Elemental and mass spectral analysis of the complex indicated the formation of a compound of the composition NdR3 x 6H2O, where R = C19H14NO6-) The reaction of neodymium(III) with acenocoumarol was studied in detail by the spectrophotometric method. The stepwise formation of three complexes, vis., NdR2+, NdR2+ and NdR3 was established in the pH region studied (pH 3.0-7.5). The equilibrium constants for 1:1, 1:2 and 1:3 complexes were determined to be log K1 = 6.20 +/- 0.06; log K2 = 3.46 +/- 0.07 and log K2) = 2.58 +/- 0.05, respectively.
IOSR Journal of Applied Chemistry, 2013
7-hydroxy-4-methyl-8-(p-methylphenylazo)coumarin (L1) and 7-hydroxy-4-methyl-8-(pmethoxyphenylazo)coumarin (L2) have been prepared and characterized by elemental analysis, infrared (IR), proton nuclear magnetic resonance (1 H NMR) and mass spectra. The important infrared (IR) spectral bands corresponding to the active groups in the two ligands and the solid complexes under investigation were studied. Also the important fragments in the ligands and complexes were done using mass spectra and the main peaks were corresponding to the molecular weights of the ligands and complexes. The solid complexes have been synthesized and characterized by elemental and thermal analyses (TG and DTA) as well as by IR, 1 H NMR, magnetic measurements, electronic transition, molar conductance, mass and electron spin resonance (ESR) spectra. The proposed steriochemical structures for the investigated metal complexes suggest octahedral geometry with respect to Mn, Co, Ni, Cu and Zn divalent metal ions with the investigated ligands 1:1 and 1:2 complexes and all of the formed complexes contain coordinated and hydrated water molecules. All of the prepared solid complexes behave as non-electrolytes in chloroform.