Experimental (FT-IR, FT-Raman, H, C NMR) and theoretical study of alkali metal 2-aminonicotinates

The influence of lithium, sodium, potassium, rubidium and cesium on the electronic system of 2-aminonicotinic acid (2-ANA) was studied by the methods of molecular spectroscopy. The vibrational (FT-IR, FT-Raman) and NMR (¹H and ¹³C) spectra of 2-aminonicotinic acid and its alkali metal salts were recorded. Characteristic shifts and changes in intensities of bands along the metal series were observed. The changes of chemical shifts of protons (¹H NMR) and carbons (¹³C NMR) in the series of studied alkali metal 2-aminonicotinates (2-AN) were observed too.Optimized geometrical structures of the studied compounds were calculated by the B3LYP method using the 6-311++G** basis set. Aromaticity indices, atomic charges, dipole moments and energies were also calculated. The theoretical chemical shifts in ¹H and ¹³C NMR spectra and theoretical wavenumbers and intensities of IR and Raman spectra were determined. The calculated parameters were compared to the experimental characteristics of the studied compounds.     

Spectral analysis (FT-IR,FT-Raman,UV and NMR), molecular docking,ADMET properties and computational studies: 2-Hydroxy-5-nitrobenzaldehyde

The hybrid correlation method was used to examine the spectra of 2-Hydroxy-5-nitrobenzaldehyde (2H5NB) in the FT-IR, FT-Raman, UV–Vis and NMR ranges. For the best molecular shape, vibrational wavenumbers, infrared intensities, and Raman activity using density functional theory, B3LYP and the 6–311++G(d,p) basis set were used. The MOLVIB software was tasked with providing an in-depth interpretation of the vibrational spectra. Intermolecular charge transfer is a result of bonding orbitals participating as donors and acceptors in all phases of NBO analysis, which stabilizes molecules. High gastrointestinal absorption, but no brain-blood barrier penetration or cytochrome P450 inhibition, were observed despite the expected ADMET characteristics and expected gastrointestinal absorption (1A2, 2C19, 2C9, 2D6 and 3A4). Following CFN and EDE, the results of molecular docking showed that 2H5NB had the highest negative mean binding affinity of ?5.717 kcal/mol, followed by CFN and EDE. 2H5NB also had a more significant hydrogen bond with the amino acid residues of selected receptor proteins. As a result, the current compound may be described as a possible analeptic agent.     

FT-IR and FT-Raman spectroscopy study of di-urethanesil hybrids doped with Mg(CF3SO3)2

In the present work di-urethane cross-linked poly(oxyethylene) (POE)/siloxane hybrids (di-urethanesils) incorporating magnesium triflate (Mg(CF₃SO₃)₂) with 100 ≥ n ≥ 2 (where n, composition, is the molar ratio of oxyethylene repeat units per Mg²⁺ ion) have been characterized by Fourier transform infrared and Raman spectroscopy to elucidate the Mg²⁺/POE, Mg²⁺/urethane, Mg²⁺/CF₃SO₃⁻ and hydrogen bonding interactions. The Mg²⁺ ions bond to POE chains and to the carbonyl oxygen atoms of the urethane linkages over the whole range of salt content studied. A crystalline POE/Mg(CF₃SO₃)₂ complex of unknown stoichiometry is formed at n = 5. “Free” and weakly coordinated CF₃SO₃⁻ ions are present in all the materials examined. Contact ion pairs emerge at n ≤ 20 and higher ionic aggregates appear at n ≤ 5.     

Vibrational spectra of Zn(II) complexes of the amino acids with hydrophobic residues

The infrared and Raman spectra of the bis-chelated Zn(II) complexes of the amino acids glycine, alanine, valine, leucine, isoleucine and phenylalanine were recorded and analyzed in relation to its structural peculiarities. Some comparisons between the recorded spectra are also presented and the characteristics of the carboxylate motions as well as those of the metal-to-ligand vibrations are discussed in detail.     

Synthesis and spectroscopic studies of novel Cu(II), Co(II), Ni(II) and Zn(II) mixed ligand complexes with saccharin and nicotinamide

Four novel mixed ligand complexes of Cu(II), Co(II), Ni(II) and Zn(II) with saccharin and nicotinamide were synthesised and characterised on the basis of elemental analysis, FT-IR spectroscopic study, UV–Vis spectrometric and magnetic susceptibility data. The structure of the Cu (II) complex is completely different from those of the Co(II), Ni(II) and Zn(II) complexes. From the frequencies of the saccharinato CO and SO₂ modes, it has been proven that the saccharinato ligands in the structure of the Cu complex are coordinated to the metal ion ([Cu(NA)₂(Sac)₂(H₂O)], where NA — nicotinamide, Sac — saccharinato ligand or ion), whilst in the Co(II), Ni(II) and Zn(II) complexes are uncoordinated and exist as ions ([M(NA)₂(H₂O)₄](Sac)₂).     

X-ray,FT-IR,ESI MS and PM5 studies of Schiff base of gossypol with allylamine and its complexes with alkali metal cations and perchlorate anion

Crystals of the Schiff base derivative of gossypol with allylamine (GSBAL) were grown and subsequently examined by X-ray diffraction and FT-IR methods. The crystal space group is C2/c with a = 16.057(1) Å, b = 14.112(1) Å, c = 27.185(2) Å, β = 99.371(5)? and Z  = 8. In the crystal, GSBAL exists in the enamine–enamine tautomeric form. The FT-IR spectral features of the crystals are in agreement with the X-ray data indicating that both parts of the molecule are similarly intramolecular hydrogen-bonded but different intermolecular hydrogen-bonded, although the molecule is symmetrically substituted. On the basis of the electrospray ionization mass spectrometry (ESI MS) experiments, it has been shown for the first time that Schiff base of gossypol forms complexes with the perchlorate anion and metal cations simultaneously. The ESI MS spectra of the 1:1:1 mixtures of GSBAL:GOS:M⁺, in the positive and negative ion detection mode, have indicated the preferential formation of the 1:1 complexes of GSBAL with M⁺ (Li, Na or K) and ClO₄ ^? over the respective complexes forming between GOS and the metal cation or the anion. The PM5 semiempirical calculations have allowed visualization of the most energetically favourable structures of these two types of GSBAL complexes.     

FT-Raman, FT-IR and NMR spectra, vibrational assignments and density functional studies of 1,3-bis(benzimidazol-2-yl)-2-thiapropane ligand and its Zn(II) halide complexes

1,3-bis(benzimidazol-2-yl)-2-thiapropane (L) ligand and its zinc halide ZnX₂ (X = Cl, Br, I) complexes have been synthesized. The compounds were characterized using the elemental analysis, molar conductivity, FT-Raman, FT-IR (mid i.r., far i.r.), ¹H and ¹³C NMR spectra, and quantum chemical calculations performed with Gaussian 03 package program set. The optimized geometries and vibrational frequencies of the ligand and [Zn(L)Cl₂] complex were calculated using the DFT/B3LYP method with a 6–31g(d) basis set. The geometry optimization of [Zn(L)Cl₂] yields a slightly distorted tetrahedral environment around Zn ion, while the molecule clearly reveals the Cs symmetry. The molar conductivity data reveals that the complexes are neutral. The ligand is bidentate, via two of the imine nitrogen atoms in the bis-imidazole ring units, and together with the monodentate coordination of the two halides to the metal centre.     

Vibrational spectra and structure of some oxalic acid/substituted pyridine (methyl-, amino-, and dihalogeno-) complexes: Hydrogen bond features

The Raman and infrared spectra of some polycrystalline substituted pyridine/oxalic acid complexes have been investigated and assignments in terms of group frequencies are given. Various hydrogen bonds (NH?O, OH?O, OH?N) are distinguished and crystal structures are proposed. For the stronger bases (methyl- or aminopyridines with pk_a ≈ 6) proton transfer occurs. The 1/1 complex contains infinite chains of hydrogen oxalate ions linked by strong OH?O hydrogen bonds with vOH between 2000 and 800 cm⁻¹. R_OH?O distances are 2.47–2.62 Å). The substituted pyridinium cations are linked to the chain backbone by medium NH?O hydrogen bonds with NH?O lengths of 2.71–2.81 Å. The 3,5-dichloropyridine forms a 2/1 adduct without proton transfer, in accordance with its pk_a (0.6), and strong OH?N hydrogen bonds occur (vOH about 2000 cm⁻¹ and ). Finally, the 2,6-dihalogenopyridine derivatives do not form complex with oxalic acid, presumably because of steric hindrance.     

Experimental and theoretical studies on vibrational spectra of 4-(2-furanylmethyleneamino)antipyrine, 4-benzylideneaminoantipyrine and 4-cinnamilideneaminoantipyrine

This work deals with the IR and Raman spectroscopy of 4-(2-furanylmethyleneamino) antipyrine (FAP), 4-benzylideneaminoantipyrine (BAP) and 4-cinnamilideneaminoantipyrine (CAP) by means of experimental and quantum chemical calculations. The equilibrium geometries, harmonic frequencies, infrared intensities and Raman scattering activities were calculated by density functional B3LYP method with the 6-31G(d) basis set. The comparisons between the calculated and experimental results covering molecular structures, assignments of fundamental vibrational modes and thermodynamic properties were investigated. The optimized molecular geometries have been compared with the experimental data obtained from XRD data, which indicates that the theoretical results agree well with the corresponding experimental values. For the three compounds, comparisons and assignments of the vibrational frequencies indicate that the calculated frequencies are close to the experimental data, and the IR spectra are comparable with some slight differences, whereas the Raman spectra are different clearly and the strongest Raman scattering actives are relative tightly to the molecular conjugative moieties linked through their Schiff base imines. The thermodynamic properties (heat capacities, entropies and enthalpy changes) and their correlations with temperatures were also obtained from the harmonic frequencies of the optimized strucutres.     

Synthesis,spectroscopic studies,antimicrobial activity,and crystal structure of a Zn(II) complex based on Voriconazole

[Zn(FZ)₂Cl₂] (1) (FZ = Voriconazole, (2R,3S)-2-(2,4-difluorophenyl)-3(5-fluoropyrimidin-4-yl)-1-(1H-1,2,4-triazol-1-yl)butan-2-ol), has been obtained through the reaction of zinc chloride and FZ and has been characterized by FT-IR, UV–vis and fluorescence spectra, elemental analysis (EA), single crystal X-ray diffraction, powder X-ray diffraction and thermogravimetric analysis (TGA). FZ was also characterized by FT-IR, UV–vis spectra, single crystal X-ray diffraction and TGA. FZ crystallizes in the chiral space group P2₁ and 1 crystallizes in chiral space group P₁ with a mononuclear structure. In 1, there are three kinds of hydrogen bonding interactions and weak stacking interactions which generate a 3-D architecture. The primary antimicrobial results show that 1 exhibits potent activity against Aspergillus (Aspergillus niger, Aspergillus terreus, Aspergillus fumigatus and Aspergillus flavus) and Candida species (Candida albicans, Candida krusei, Candida glabrata and Cryptococcus neoformans), higher than that of free FZ. Fluorescence spectra of 1 and FZ have been discussed.     

FT-Raman and high-pressure infrared spectroscopic studies of dicalcium phosphate dihydrate (CaHPO4·2H2O) and anhydrous dicalcium phosphate (CaHPO4)

The FT-Raman spectra and the pressure dependence of the infrared spectra of the hydrated and anhydrous forms of dicalcium phosphate, CaHPO₄ · 2H₂O and CaHPO₄, have been studied. The hydrated salt exhibits a phase transition at 21 kbar (1.0 kbar=0.1 Gpa) but no high pressure transition was observed for anhydrous dicalcium phosphate. The O–H stretching frequencies of the water molecules in CaHPO₄·2H₂O all showed negative pressure dependences and correlate with the OO distances. The PO–H stretch increased with increasing pressure, indicating a strong hydrogen bond. The frequencies associated with the phosphate ion showed a normal pressure dependence.     

Synthesis,characterization and cytotoxic/cytostatic activity of Sm(III) and Gd(III) complexes

New Sm(III) and Gd(III) complexes of deprotonated 4-hydroxy-3[1-(4-nitrophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one (Acenocoumarol) were synthesized and characterized using FT-IR, FT-Raman, NMR spectra, and elemental analyses. The vibrational study gave evidence for the coordination of ligand to lanthanide ions. The ligand and its lanthanide(III) complexes were tested for their cytotoxic/cytostatic activity against two tumor cell lines and peritoneal mouse macrophages. The Sm(III) and Gd(III) complexes exhibit good activity against melanoma B16 and fibrosarcoma L929 and are stronger inhibitors of tumor cell proliferation than the ligand. Besides their cytotoxicity to tumor cells, Acenocoumarol and its gadolinium(III) and samarium(III) complexes modulate NO generation in activated macrophages.     

Big macrocyclic assemblies of carboranes (big MACs): synthesis and crystal structure of a macrocyclic assembly of four carboranes containing alternate ortho- and meta-carborane icosahedra linked by para-phenylene units

The macrocyclic compound, [1,2-C₂B₁₀H₁₀-1,4-C₆H₄-1,7-C₂B₁₀H₁₀-1,4-C₆H₄]₂ (5)—a novel cyclooctaphane, was prepared by condensation of the C,C′-dicopper(I) derivative of meta-carborane with 1,2-bis(4-iodophenyl)-ortho-carborane. The X-ray crystal structure of 5·C₆H₆·6C₆H₁₂ was determined at 150 K, revealing an extremely loose packing mode. Molecule 5 has a crystallographic C_s and local C_2v symmetry; the macrocycle adopts a butterfly (dihedral angle 143°) conformation with the ortho-carborane units at the wingtips and the phenylene ring planes roughly perpendicular to the wing planes. Multinuclear NMR spectra suggest that molecule 5 in solution inverts rapidly via the planar D_2h geometry, which (from ab initio HF/6-31G* calculations) is only 1 kcal mol⁻¹ higher in energy than the C_2v one. An attempt to prepare an even larger macrocycle, comprising three para-carborane and three ortho-carborane units linked by six para-phenylene units, was unsuccessful.     

NMR and ab initio studies of Mg,Ca, Zn,Cu alizarin complexes

Complexation of Mg²⁺, Ca²⁺, Zn²⁺ and Cu²⁺ with alizarin, characterized by NMR and theoretical studies (DFT, B3LYP/6-31G(d,p) PCM and NMR GIAO B3LYP/IGLOIII), indicated that the metal ion is attached to two hydroxyl groups in a bidentate mode. The alternative complexation in the bidentate mode, with only one hydroxyl group and a carbonyl oxygen, is less possible as it has a higher energy.     

Vibrational spectroscopic studies of 4,4′-bipyridyl metal(II) tetracyanonickelate complexes and their clathrates

The infrared spectra of M(4,4-bipyridyl)Ni(CN)₄ complexes (M=Ni or Cd) and their dioxane, benzene, toluene, aniline andN,N-dimethylaniline clathrates are reported. Additional information regarding the structure of the host lattice is obtained from the Raman spectra of the M=Cd complex. It is shown that the structure of the host lattice consists of infinite polymeric layers of {M-Ni(CN)₄} analogous to those of Hofmann type clathrates that have tetragonal symmetry. Bidentate 4,4-bipyridyl molecules form bridges between the metal atoms {M} in the adjacent {M-Ni(CN)₄} layers. It is found that the 4,4-bipyridyl molecules are centrosymmetric in this structure.Presented at the Fourth International Symposium on Inclusion Phenomena and the Third International Symposium on Cyclodextrins, Lancaster, U.K., 20–25 July 1986     

FT-Raman and FTIR spectra, normal coordinate analysis and ab initio computations of (2-methylphenoxy)acetic acid dimer

The Fourier Transform Raman and infrared spectra of the crystallized herbicide (2-methylphenoxy)acetic acid (MPA) have been recorded in the region 4000–400 cm⁻¹. The geometry, intermolecular hydrogen bond, and harmonic vibrational frequencies of MPA have been investigated with the help of B3LYP density functional theory (DFT) methods. The calculated molecular geometry has been compared with the experimental data obtained from XRD data. The assignments of the vibrational spectra have been carried out with the aid of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMFF). The strong doubly hydrogen bonded interface of the dimerized system is well demonstrated by the red shift in OH stretching frequency concomitant with the elongation of bond length. The most stable structure of the dimer possesses center of symmetry and interaction energy of −83.642 kJ mol⁻¹ after the basis set superposition error (BSSE) correction by the counterpoise (CP) method. The natural bond orbital analysis (NBO) ascertains that the delocalization of unpaired electron of oxygen atom onto the CO bond causes double bond character.     

Vibrational Spectroscopic Studies on the tn-Td-Type Mn(tn)Zn(CN)4_2C6H6 and the Chelated tn-Td-Type Zn(tn)Zn(CN)4_2C6H6 Clathrates

IR spectra of Mn(trimethylenediamine)Zn(CN)₄2C₆H₆ and IR and Raman spectra of Zn(trimethylenediamine)Zn(CN)₄_2C₆H₆ are reported. The spectral data suggest that the host frameworks of these compounds are similar to those of the tn-Td-type Cd(trimethylenediamine)M(CN)₄_2benzene (M = Cd or Hg) and the chelated pn-Td-type Cd(propylenediamine)Cd(CN)₄_1,2-dichloro-ethane clathrates, respectively.     

Preparation and structural studies on dibutyltin(IV) complexes with pyridine mono- and dicarboxylic acids

A number of organotin(IV) complexes with pyridine mono- and dicarboxylic acids (containing ligating -COOH group(s) and aromatic {N} atoms) were prepared in the solid state. The bonding sites of the ligands were determined by means of FT-IR spectroscopic measurements. It was found that in most cases the -COO⁻ groups form bridges between two central {Sn} atoms, thereby leading to polymeric (oligomeric) complexes. On this basis, the experimental ¹¹⁹Sn Mössbauer spectroscopic data were treated with partial quadrupole splitting approximations. The calculations predicted the existence of complexes with octahedral (oh) and trigonal-bipyramidal (tbp) structures, but the formation of complexes with pentagonal-bipyramidal (pbp) structures could not be ruled out. Single-crystals of 2-picolinic and pyridine-2,6-dicarboxylic acid Bu₂Sn(IV)²⁺ complexes were obtained. The X-ray diffraction studies revealed that the central {Sn} atoms are in a pbp environment with bond distances characteristic of organotin(IV) compounds. The two butyl groups are located in axial positions. ¹¹⁹Sn NMR measurements in dmso solution and in the solid state indicated that the polymeric structures of the complexes are not retained in solution. The results of the solid-state ¹¹⁹Sn NMR measurements for compounds 1a, 2a and 6a are in agreement with the structures predicted by Mössbauer spectroscopy and revealed by X-ray diffraction.     

Synthesis,characterization and screening of biological activity of Zn(II), Fe(II) and Mn(II) complexes with trithiocyanuric acid

New Zn(II), Fe(II) and Mn(II) complexes with a combination of nitrogen-donor ligands and trithiocyanuric acid (ttcH₃) were prepared and characterized by elemental analysis, IR and UV–Vis spectroscopies. The antitumor activity of the prepared complexes, together with already known Ni(II) species, were assayed in vitro against G-361 (human malignant melanoma), HOS (human osteogenic sarcoma), K-562 (human chronic myelogenous leukaemia) and MCF-7 (human breast adenocarcinoma) tumor cell lines. The IC₅₀ values of the Fe(II) and Mn(II) compounds turned out to be lower than those of cisplatin and oxaliplatin. The antimicrobial activities were evaluated by MIC against bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis). The molecular structure of [Zn(taa)(ttcH)] · H₂O (taa = tris(2-aminoethyl)amine) was determined by X-ray diffraction. The central atom is pentacoordinated by four N atoms of taa and one N atom of the ttcH dianion.     

Synthesis and structural studies of complexes of Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with substituted chalcones

Complexes of Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with 3-(2-pyridyl)-1-(2-hydroxy phenyl)-2-propen-1-one (PHPO), 3-(1-naphthyl)-1-(2-hydroxy phenyl)-2-propen-1-one (NHPO) and 3-(3,4-dimethoxy phenyl)-1-(2-hydroxy phenyl)-2-propen-1-one (DMPHPO) have been synthesized and characterized by analytical, conductivity, thermal, magnetic, infrared, electronic and electron spin resonance data. Based on analytical data the stoichiometry of the complexes has been found to be 1 : 2. The conductivity data show that all these complexes are non-electrolytes. The infrared spectral data indicate that the ligand PHPO acts as uninegative tridentately towards Co(II) and Ni(II) and bidentately with Cu(II), Zn(II) and Cd(II). Ligands like NHPO and DMPHPO act as uninegative bidentately with all the metal ions. The electronic spectral data suggest that all the Co(II) complexes and Ni(II) of PHPO complex are octahedral and all the Cu(II) and Ni(II) of NHPO and DMPHPO complex are square-planar. The complex of Zn(II) and Cd(II) are tetrahedral. ESR parameters of Cu(II) complexes have been calculated and relevant conclusions have been drawn with respect to the nature of bonds present in them.