Nujol Mull Research Articles

Experimental and theoretical quantum chemical studies of 2-(2-acetamidophenyl)-2-oxo-N-(pyridin-2-ylmethyl)acetamide and its copper(II) complex: molecular docking simulation of the designed coordinated ligand with insulin-like growth factor-1 receptor (IGF-1R)

Newly synthesized ligand 2-(2- acetamidophenyl)-2-oxo-N-(pyridin-2-ylmethyl)acetamide and its copper(II) complex were characterized by elemental analyses, FT-IR, UV–Vis., ESR, 1H-NMR, and thermal analysis along with the theoretical quantum chemical studies. Combined experimental and theoretical DFT (density functional theory) studies showed the ligand to be a tridentate ligand with three coordinate bonds. The complex was suggested to be in a distorted octahedral structure with dx2-y2 ground state. The activation energy, ΔE*; entropy ΔS*; enthalpy ΔH* and order of reaction has been derived from differential thermogravimetric (DTA) curve, using Horowitz–Metzeger method. The nujol mull electronic spectrum of the ligand and Cu(II) complex have been recorded and the difference of the excited and ground state densities has also been theoretically calculated and plotted to investigate the movement of electrons on excitation. The Cu(II) complex was evaluated for its antibacterial activity against two bacterial species, namely Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Antifungal screening was performed against two species (Condida albicans and Aspergillus flavus). The complex under investigation was found to possess notable biological activity. Molecular docking investigation predicted different types of non-covalent interactions of the synthesized ligand towards Insulin-like growth factor 1 receptor (ID: 5FXR).

Investigation and assessment of epoxy resin adhesives using Fourier‐transform infrared spectrometry

AbstractEpoxy resin adhesives are very attractive for many industries, especially in the aerospace and automotive industries because they eliminate heavy connection elements, such as bolts and screws, and reduce the total weight. This study assesses developed epoxy resin adhesives using Fourier‐transform infrared spectrometry. The curing reaction between Epikote 828 epoxy resin and Epikure polyamidoamine curing agent 3090, and the chemical structure of the additives (CAB‐O‐SIL TS‐720) used for rheology control and six different types of fillers (calcite with particle diameters of 700 nm, 5 μm, and 10 μm, coated calcite with a particle diameter of 900 nm, and barite and calcite with a particle diameter of 5 μm) employed in the adhesives are investigated. The Fourier‐transform infrared spectrometry results of the epoxy resin and curing agent demonstrate that 83.5 % epoxy conversion is achieved at a temperature of 25 °C. The chemical composition of the additives with six different types of fillers and 1 %, 3 %, and 5 % additions of CAB‐O‐SIL TS‐720 prepared in both nujol mull and potassium bromide discs is characterized using Fourier‐transform infrared spectrometry. The potassium bromide discs yield higher intensities owing to good packing of cubic particles of potassium bromide with nano particle size CAB‐O‐SIL TS‐720 and all filler types.

Protonation of the Dodecahydro-closo-Dodecaborate Anion in CH3CN/CF3COOH

The behavior of the [B12H12]2– anion in CH3CN, CF3COOH, and the CH3CN/CF3COOH system is studied by IR spectroscopy. Based on the IR spectroscopy data correlated with the data obtained when studying the protonation processes of boron cluster anions [B6H6]2– and [B10H10]2–, the possibility to prepare the protonated form of the closo-dodecaborate anion, namely monoanion [B12H13]–, is concluded in CF3COOH and the CH3CN/CF3COOH system. In the IR spectra of salts of the protonated forms of anions [BnHn]2– (n = 6, 10, 12) in solutions and Nujol mulls, a high-frequency shift of the ν(BH) absorption bands is observed as compared with the spectra of salts of non-protonated anions Cat2[BnHn] (Δν = 70–100 cm–1).

Structural, spectral, magnetic and thermal studies of 5-(thiophene-2-ylmethine azo) uracil metal complexes

Mono- and bimetallic 5-(thiophene-2-ylmethine azo) uracil complexes were prepared in a pure ethanol or ammoniacal solution. The complexes were characterized by elemental analyses, thermal analyses, magnetic moment and spectroscopic measurements. The infrared and 1H-NMR studies revealed that the ligand reacts with all metal ions in a neutral keto form. Also, the ligand behaves as a tridentate or bidentate and coordinated with metal ions by ONS, NS and ON donors atoms, where azomethane nitrogen atom, and/or sulfur atom of thiophene ring and oxygen atom of uracil ring are participated to construct mononuclear Co(II), Ni(II), Zn(II), bimetallic Cd(II); mononuclear Cu(II) and Mn(II) complexes, respectively. However, in case of bimetallic Co(II) 7 and Ni(II) 8 ammine complexes, the ligand bridge is considered to indicate the ligand has tetra- and pentadentate character toward two metal ions, respectively. The magnetic moment values and the Nujol mull electronic spectra showed that all complexes have an octahedral geometry, except Cu(II) complex, 4 has a square planar structure. All the thermal decomposition processes led to formation of metal oxides. The hydrated complexes displayed a higher thermal stability than that of ammine complexes. Theoretical investigations have also been carried out at CAM-B3LYP/LANL2DZ to study the structure of the ligand and its Mn(II) complex. The results confirmed the experimental discussion.

INFRARED SPECTRA OF THIOSACCHARINATES OF CADMIUM AND LEAD COMPARISON WITH THE ANALOGOUS METAL SACCHARINATES

A b s t r a c t: The Fourier transform (FT) infrared spectra of thiosaccharinates of cadmium and lead in the 4000–400 cm–1 region were studied. Although the observed resemblance between the spectra recorded in KBr pellets suggests a possible similarity between their structures as well, the powder X-ray diagrams show that these two compounds are not isomorphous. The presence of broad and intense bands in the region of the HOH stretchings shows that thiosaccharinate of cadmium is a crystalline hydrate and the spectral picture in the region of the O-D stretchings of the isotopically isolated HOD molecules in the partially deuterated analogue indicates that present in its structure are at least two types of crystallographically different water molecules involved in the formation of weak hydrogen bonds. The room temperature (RT) spectrum of lead thiosaccharinate in the region of the ν(HOH) modes differs significantly from the spectrum recorded at the boiling temperature of liquid nitrogen (LNT), which may perhaps be interpreted as an indication that a phase transition is taking place on lowering the temperature. The spectrum of lead thiosaccharinate was recorded in a Nujol mull as well. While the KBr and Nujol spectra are essentially identical in the region below 1600 cm–1, no bands are observed in the HOH stretching region of the mull spectra. In fact, it was shown that the appearance of the spectra of lead thiosaccharinates depends on the emulsion preparation rate. A comparison of the spectral characteristics of the thiosaccharinates of cadmium and lead with those of the corresponding saccharinates (their crystal structures are known) was made, special attention being paid to the analysis of the SO2 stretching region in the saccharinate and thiosaccharinate compounds.

Vibrational spectroscopic, optical and thermal properties of a hybride pyridazine perchlorate complex—An experimental and theoretical study

Various methods of experiment: differential scanning calorimetry (DSC), differential thermal analysis (DTA), thermogravimetric analysis (TGA) and infrared (IR) spectroscopy have been used to investigate the phase transitions in pyridazine perchlorate crystal. DSC showed the existence of phase transition at T = 341 K. The vibrational IR spectra in Nujol and Perfluorolube mulls were studied in a wide temperature range, from room temperature to 380 K. Special attention was put on the temperatures near the phase transition temperature. The temperature changes of wavenumbers, gravity center and band intensities were analyzed to clarify the phase transition molecular mechanism. Information about hydrogen bonds was obtained. For more detailed band assignment and overall spectral presentation Raman and far infrared (FT–FIR) spectra at room temperature have been carried out. The experimental data interpretation was supported by theoretical calculations based on density functional theory, with the B3LYP method and 6–311++G(d,p) basic set. Some theoretical conformations were analyzed. Calculated normal vibrational modes of the molecule, their frequencies and intensities were compared with these recorded in experiment.

Reactivity and molecular modeling of new solvatochromic mixed-ligand copper(II) chelates of 2-acetylbutyrolactone and dinitrogen bases

A new series of solvatochromic mononuclear mixed ligand chelates with the general formula: Cu(AcBL)(L)X; where AcBL=2-acetylbutyrolactonate, L=N,N,N′,N′-tetramethylethylenediamine (Me4en), N,N,N′,N′-tetramethylpropylene diamine (Me4pn), 1,10-phenanthroline (Phen) or 2,2′-bipyridyl (Bipy) and X=ClO4−, NO3− or Br− have been synthesized and characterized by the analytical and spectral methods, as well as magnetic and molar conductance measurements. The d–d absorption bands of Me4en-chelates as Nujol mulls or weak donor solvents solutions revealed square-planar, distorted octahedral and/or distorted trigonal bipyramid geometries for the perchlorate, nitrate and bromide chelates, respectively. However, an octahedral structure is identified for chelates in strong donor solvents. Perchlorate chelates show a remarkable color change from violet to green as the Lewis basicity of the donor solvent increases, whereas bromide chelates are mainly affected by the Lewis acidity of solvent. Specific and non-specific interactions of solvent molecules with the chelates were investigated on the basis of unified solvation model. Structural parameters of the free ligands and their Cu(II)-chelates have been calculated on the basis of semiempirical PM3 level and correlated with the experimental data.

ChemInform Abstract: First Example of a New Multicomponent Reaction of a Tetrahydropyridine Ring Expansion.

In a continuation of work on the synthesis of eightand nine-membered nitrogen-containing heterocycles [1-3] and on the use of the Ugi reaction in the synthesis of benzodiazepine derivatives [4], we decided to develop a new isocyanide multicomponent reaction (MCR) using the reaction which we have discovered for the tandem expansion of heteroannelated tetrahydropyridines and azepines under the influence of activated alkynes. The experimental data we obtained earlier allowed us to suggest with certainty that propiolic acid, in contrast to its esters did not give products of the ring expansion with heteroannelated tetrahydropyridines. We have proposed that if propiolic acid was used as the carboxylic component in the Passerini reaction [5] then the oxoethylpropiolate A formed in situ, being an activated alkyne, might react with heteroannelated tetrahydropyridines introduced in this reaction as a fourth component. As a model experiment, we studied a MCR with tetrahydrothienopyridine 1 [6], butyraldehyde (2), propiolic acid (3), and isonitrile 4. The reaction was carried out at a temperature of -5 to 0°C in an atmosphere of argon. As a result the required thienoazocine 5 was isolated from the reaction mixture in a yield of 32%. Thus, we have found the first example of a multicomponent reaction for the expansion of a tetrahydropyridine ring. Despite the small yield of the required azocine, this reaction may serve as an effective method for the synthesis of difficult to obtain derivatives of medium nitrogen heterocycles. H and C NMR spectra were recorded with a Bruker WP-400 spectrometer (400 and 100 MHz respectively) in CDCl3 solution with TMS as internal standard. The assignment of the signals in the H NMR spectra was based on the data from the H-H COSY experiment. IR spectra of nujol mulls were recorded on an Infralum FT-801 Fourier spectrometer. The LC/MS spectra were obtained with a system which included an Agilent 1100 series liquid chromatograph and an Agilent Technologies LC/MSD VL mass spectrometer (electrospray injection, APCI), ELSD Sedex 75 detector. Butyraldehyde (2), propiolic acid (3), and the isonitrile 4 were commercial products. The aldehyde 2 was distilled at normal pressure under argon before use in the reaction, the other reagents were used without additional purification.

Reaction of hydroquinone with 2-ethoxyvinylphosphonyl dichloride

Earlier, we have reported a one-step method for the synthesis of new cage-type phosphonates based on the condensation of 2-ethoxyvinylphosphonyl dichloride1 (1) with resorcinol and its derivatives in dioxane in the presence of trifluoroacetic acid.2,3 The presence of hydroxyl groups in the composition of bicyclic phosphonates having a rigid cage structure opens a possibility for the preparation of new macrocyclic and polymeric compounds. Vector 22 (Bruker) Fourier-spectrometer in the range of 400—3800 cm–1 for the Nujol mulls, MALDI-TOF mass spectrum was obtained on a ULTRAFLEX III mass spectrometer using plastic and metal plates, 2,5dihydroxybenzoic acid (2,5-DHB) was used as a matrix. 6,12-Dihydroxy-1-oxo-2,16-dioxa-1phosphatetracyclo[7.7.1.03,8.010,15]heptadeca-3,5,7,10,12,14hexaene (3). 2-Ethoxyvinylphosphonyl dichloride 1 (1.0 g, 5.3 mmol) was added dropwise to a refluxed mixture of hydroquinone 2 (1.17 g, 10.6 mmol) and trifluoroacetic acid (1.21 g, 10.6 mmol) in toluene (25 mL) (see Ref. 1) and the mixture was refluxed for 3 h with stirring. A precipitate formed was filtered off, washed with distilled water, and dried in vacuo until the weight was constant to obtain compound 3 (1.2 g, 78%), m.p. >350 °C. Found (%): C, 57.31; H, 3.71; P, 10.62. C14H11O5P. Calculated (%): C, 57.93; H, 3.79; P, 10.69. 1H NMR, δ: 2.59 (dd, 2 H, PCH2, JH,H = 3.58 Hz, JP,H = 16.14 Hz); 4.60 (dt, 1 H, CH, JH,H = 3.58 Hz, JP,H = 34.43 Hz); 6.60 (dd, 2 H, o-CH arom., JH,H = 8.60 Hz, JP,H = 1.79 Hz); 6.83 (s, 2 H, o-CH arom.); 6.85 (d, 2 H, m-CH arom., JH,H = 8.60 Hz); 9.73 (br.s, 2 H, OH). 31P NMR, δ: 15.05. IR, ν/cm–1: 1270 (P=O), 1594 (arom.), 3250—3550 (OH). MS (MALDI), m/z: 312. 68 [M + Na]+, 328.70 [M + K]+. In order to broaden the scope of bicyclic phosphonates of this series, we carried out the reaction of dichlorophosphonate 1 with hydroquinone (2) (Scheme 1), which resulted in the obtaining of the cage-type phosphonate 3. It should be noted that we considerably modified the procedure. The reaction was carried out in refluxing toluene instead of dioxane used earlier, in this case the reaction required 3 h instead of several days, and the product precipitated from the reaction mixture virtually did not require additional purification.

First example of a new multicomponent reaction of a tetrahydropyridine ring expansion

In a continuation of work on the synthesis of eightand nine-membered nitrogen-containing heterocycles [1-3] and on the use of the Ugi reaction in the synthesis of benzodiazepine derivatives [4], we decided to develop a new isocyanide multicomponent reaction (MCR) using the reaction which we have discovered for the tandem expansion of heteroannelated tetrahydropyridines and azepines under the influence of activated alkynes. The experimental data we obtained earlier allowed us to suggest with certainty that propiolic acid, in contrast to its esters did not give products of the ring expansion with heteroannelated tetrahydropyridines. We have proposed that if propiolic acid was used as the carboxylic component in the Passerini reaction [5] then the oxoethylpropiolate A formed in situ, being an activated alkyne, might react with heteroannelated tetrahydropyridines introduced in this reaction as a fourth component. As a model experiment, we studied a MCR with tetrahydrothienopyridine 1 [6], butyraldehyde (2), propiolic acid (3), and isonitrile 4. The reaction was carried out at a temperature of -5 to 0°C in an atmosphere of argon. As a result the required thienoazocine 5 was isolated from the reaction mixture in a yield of 32%. Thus, we have found the first example of a multicomponent reaction for the expansion of a tetrahydropyridine ring. Despite the small yield of the required azocine, this reaction may serve as an effective method for the synthesis of difficult to obtain derivatives of medium nitrogen heterocycles. H and C NMR spectra were recorded with a Bruker WP-400 spectrometer (400 and 100 MHz respectively) in CDCl3 solution with TMS as internal standard. The assignment of the signals in the H NMR spectra was based on the data from the H-H COSY experiment. IR spectra of nujol mulls were recorded on an Infralum FT-801 Fourier spectrometer. The LC/MS spectra were obtained with a system which included an Agilent 1100 series liquid chromatograph and an Agilent Technologies LC/MSD VL mass spectrometer (electrospray injection, APCI), ELSD Sedex 75 detector. Butyraldehyde (2), propiolic acid (3), and the isonitrile 4 were commercial products. The aldehyde 2 was distilled at normal pressure under argon before use in the reaction, the other reagents were used without additional purification.

Vibrational spectroscopic, optical and thermal properties of a deuterated ferroic crystal, [(CH2OD)3CND3]2SiF6—An experimental and theoretical study

[(CH2OD)3CND3]2SiF6 ferroic crystal, abbreviated as D-(TRIS)2SiF6 crystal was investigated. Optical (linear birefringence) and thermal (differential scanning calorimetry, DSC) measurements indicated a solid–solid phase transition (PT) of the first order at 185K. The vibrational infrared spectra of powdered D-(TRIS)2SiF6 crystal in Nujol and Fluorolube mulls were studied in the wide range of temperature, from 308K to 133K. The temperature changes of wavenumber, width, centre of gravity position and intensity of the bands were analyzed to clarify the molecular mechanism of the phase transition and the contribution of SiF62− and CH2OD groups to the PT. A wide range (4000–400cm−1) of internal vibrations of the DTRIS+ and SiF62− ions was investigated and the assignment of the observed infrared absorption bands was discussed. Raman spectra of the crystal at room temperature (RT) were recorded and discussed in relation to the structure of isostructural (TRIS)2SiF6 crystal in the range (4000–400cm−1). Theoretical calculations were made based on density functional theory (DFT). The calculated normal vibrational modes of the molecules, their intensities and frequencies were compared with those obtained from experimental data.

Kinetics of interconversion of sulphamethoxydiazine crystal forms.

Abstract A quantitative Nujol mull technique is described for the determination of sulphamethoxydiazine crystal forms in mixtures, so that the rates of their interconversion may be determined. The technique is applied to the transformations taking place in the more thermo-dynamically active as well as biologically available crystal form (Form II). Kinetic parameters indicate a highly temperature dependent transformation (Ea ⋍ 100 kcal mol−1; 418·6 kJ mol−1) of Form II to the more stable Form I. Suspension in water results in a much faster transformation of Form II (Ea ⋍ 20 kcal mol−1; 83·7 kJ mol−1, t1/2 ⋍ 15 min) to the water-stable Form III. Water and water vapour are shown to be important factors in the transformation of Form II at room temperature.

Experimental and theoretical study of the IR spectrum of [(CH2OH)3CNH3]2SiF6 crystal

[(CH2OH)3CNH3]2SiF6, (tris(hydroxymethyl)aminomethane)2SiF6 crystal, abbreviated as (TRIS)2SiF6 crystal, exhibits a solid–solid phase transition (PT) at 182K. The phase transition is connected with reorientational motion of SiF62− and –CH2OH groups. The vibrational infrared spectra of powdered (TRIS)2SiF6 crystal in Nujol and Fluorolube mulls were studied in the wide range of temperatures, from 320K to 133K. A wide region of internal vibrations of the TRIS+ and SiF62− ions was investigated. Temperature changes of wavenumber, width, centre of gravity, and intensity of bands were analyzed to clarify the molecular mechanism of the phase transitions. Theoretical calculations were made based on density functional theory (DFT). The calculated normal vibrational modes of the molecules, their frequencies and intensities were compared with those obtained from experimental data.

Synthesis, spectral, thermal and antimicrobial studies of some new tri metallic biologically active ceftriaxone complexes

Iron, cobalt, nickel and copper complexes of ceftriaxone were prepared in 1:3 ligand:metal ratio to examine the ligating properties of the different moieties of the drug. The complexes were found to have high percentages of coordinated water molecules. The modes of bonding were discussed depending on the infrared spectral absorption peaks of the different allowed vibrations. The Nujol mull electronic absorption spectra and the magnetic moment values indicated the Oh geometry of the metal ions in the complexes. The ESR spectra of the iron, cobalt, and copper complexes were determined and discussed. The thermal behaviors of the complexes were studied by TG and DTA techniques. The antimicrobial activities of the complexes were examined and compared to that of the ceftriaxone itself.

ChemInform Abstract: Complexes of Tin(II) and Tin(IV) Halides with p-Nitrosodimethylaniline and p-Nitrosodiethylaniline.

Abstract Eleven new complexes of tin(II) and tin(IV) halides with p-nitrosodimethylaniline and p-nitrosodiethylaniline have been synthesized and characterized by their magnetic and spectral properties. Coordination numbers of one, two and four with respect to the ligands have been observed for these compounds. The electronic spectra of the complexes consist of intraligand transitions in methanol, nitromethane and as nujol mulls. The infrared spectra indicate that the ligands coordinate through the nitroso group, while the magnetic data show that the molecules are unsymmetrical. Tetrahedral coordination about the tin atom has been proposed for the tin(II) complexes while the tin(IV) complexes are presumed to be octahedral.

Potential anti‐fouling agents: metal complexes of 3‐(2‐furylidene)hydrazino‐5,6‐diphenyl‐1,2,4‐triazine

PurposeThe purpose of this paper is to develop a number of new anti‐fouling agents that are friendlier to the environment.Design/methodology/approachSeven copper(II) and cobalt complexes of 3‐(2‐furylidene) hydrazine‐5,6‐diphenyl‐1,2,4‐triazine (L) were prepared by interacting 3‐(2‐furylidene) hydrazino‐5,6‐diphenyl‐1,2,4‐triazine (L) with cobalt(II) and copper salts. The structures of the prepared complexes were confirmed by elemental analyses, IR and nujol mull electronic spectra, as well as magnetic susceptibility measurements. The anti‐fouling activity was measured on barnacle larvae.FindingsThe in vitro toxicity of the organic ligand and its cobalt and copper complexes on barnacle larvae was measured. The results indicated that the toxicity of the ligand increased upon complexation and that copper complexes are the most active ones.Originality/valueSuccessful development of some new copper(II) and cobalt complexes of 1,2,4‐triazine that have in vitro anti‐fouling activity against barnacle larvae and might be safe to the marine environment.

Raman and IR spectra of the unstable ionic species potassium trimethylsilanolate: The role of the counterion in its theoretical interpretation

AbstractWe have accomplished a reliable assignment of the vibrational spectra of the ionic species potassium trimethylsilanolate, which is unstable towards hydrolysis and self‐condensation, by means of the combined use of experimental data and theoretical density functional theory (DFT) calculations. We report the first record of the Raman spectrum of the pure solid. Additionally, we have newly recorded its IR spectrum in Nujol mull and for the first time in Fluorolube mull, completing the experimental data available in the literature about this chemical species. Further, in order to discuss the convenience of including the counterion in the model used for the quantum‐mechanical calculations of its vibrational spectra, we have compared the performance of three different theoretical models, namely, the isolated trimethylsilanolate anion, a theoretical monomer of potassium trimethylsilanolate and a simplified ionic cluster model based on its crystalline structure. Copyright © 2007 John Wiley & Sons, Ltd.

Characterization of Infrared Matrix-Assisted Laser Desorption Ionization Samples by Fourier Transform Infrared Attenuated TotalReflection Spectroscopy

Fourier transform infrared attenuated total reflection (FT-IR ATR) spectroscopy was used to characterize thin films of succinic acid, a matrix compound commonly used with infrared matrix-assisted laser desorption ionization (IR-MALDI) mass spectrometry. IR spectra of succinic acid thin films deposited alone and in combination with the analyte biomolecules insulin and cytochrome c were obtained by FT-IR ATR spectroscopy. Spectra of analyte and matrix alone were similar to those obtained previously from KBr pellets, Nujol mull, or thin-film absorption, although the ATR spectra have significantly lower background interferences. Thin films deposited from mixtures of water and methanol have additional peaks compared to films deposited from a methanol solution. These additional peaks are attributed to carboxylate groups stabilized by residual water molecules. No evidence was found to suggest that residual water absorption contributes to absorption at wavelengths typically used for IR-MALDI. Absorption of energy by analyte vibrational modes with rapid energy transfer to the matrix is suggested as a contributor to desorption and ionization consistent with the FT-IR ATR results.

Thermal and electrical conductivity properties of some CrIII, MnIIand amino alcohol complexes

CrIII, MnII and UO2II amino alcohol complexes were prepared and analyzed. The IR spectra proved that the ligation occurs via oxygen and nitrogen atoms. The nujol mull electronic absorption spectra joined with the room temperature magnetic moment values proved that the complexes are of Oh geometry. The thermal behaviour of the complexes was studied by DTA and TG techniques. The mechanism of the decomposition was suggested. The thermodynamic parameters of the decomposition were evaluated and discussed. The entropy of activation changes, ΔS*, showed that the transition states are more ordered than the reacting complexes. The D.C. electrical conductivity measurements of Cr- and Mn-amino alcohol complexes are of semiconductor behaviour. Empirical equations were deduced for the conduction of the investigated complexes.

Spectral and magnetic properties of phenylazo-6-aminouracil complexes

Complexes of Co II, Ni II and Cu II with substituted phenylazo-6-aminouracils containing (-H, p-OH, p-CH 3, p-OCH 3 p-COOH) have been synthesized and characterized by elemental analysis, magnetic measurements and spectral measurements (IR, UV–Vis, ESR). Infrared spectra assigned the fundamental bands of the major groups, OH, NH, CH, CO, CN, NN, CN and CO (ν, δ and γ modes of vibrations). The absence of ν OH and the appearance of ν CO in the infrared spectra of the free ligands of 5-( p-tolyl and p-anisylazo)-6-aminouracil, assigned the keto structure, whereas in cases of 5-(phenyl, p-hydroxyphenyl and p-carboxyphenylazo)-6-aminouracil ligands, the data showed strong ν OH and ν CO bands to assign keto–enol tautomerisms. The modes of interactions between the ligands and the metals were discussed, where oxygen and nitrogen atoms (of amino–amide groups) are involved in chelation. The azo group was not involved in chelation for all the prepared complexes except those of copper complexes derived from 5-(phenyl, p-tolyl, p-hydroxyphenyl and p-carboxyphenylazo)-6-aminouracils. The room temperature effective magnetic moment values, the Nujol mull spectra and ESR proved that all the prepared complexes were of octahedral geometry, except the nickel complex derived from 5-(phenylazo)-6-aminouracil and cobalt complex derived from 5-( p-carboxy-phenylazo)-6-aminouracil were square planar.