IR Spectral Investigations Research Articles

Non-template synthesis of ‘N 4’ di- and tetra-amide macrocylic ligands with variable ring sizes

Nine new macrocyclic ligands containing two- or four-amide groups have been prepared by the cyclization reaction of three different diamines with acid chlorides (oxalyl dichloride or malonyl dichloride), diesters (diethyl oxalate or diethyl malonate) or 1,2-dichloroethane. The macrocycles prepared are four tetraaza-14-crown-4, four tetraaza-15-crown-4 and one tetraaza-16-crown-4. All the macrocyclic ligands were characterized by elemental analysis and, IR, UV, NMR and mass spectral investigations.

Induced Smectic-G Phase Through Intermolecular Hydrogen Bonding, Part XIII: Impact of a Nematogen on Phase Behaviour of Hydrogen-Bonded Liquid Crystals

A series of hydrogen-bonded mesogens, p-( p′-methoxybenzylidene)-cyanoaniline:p-n-alkoxybenzoic acids (MBCA:nABA), is synthesised by using liquid-crystalline p-n-alkoxybenzoic acids (nABA) (where n represents alkoxy carbon numbers, 3-10 and 12) and a nematogen, p-( p′-methoxybenzylidene)-cyanoaniline (MBCA). The thermal and phase behaviour of these compounds is studied by thermal microscopy (TM) and differential scanning calorimetry (DCS) techniques. These studies reveal the induction of smectic-G phase in all the compounds. The structural elucidation pertaining to the formation and stabilisation of intermolecular hydrogen bonding is carried out by a detailed IR spectral investigation. The impact of imino group of the nematogen, MBCA, on the liquid-crystallinity of the present series is realised from the comparative studies made on the reported analogous series, p-aminobenzonitrile:p-n-alkoxybenzoic acids (ABN:nABA).

Thermoanalytical and IR-spectral investigation of Fe(III) complexes with nicotinamide

The paper describes the synthesis, characterization and thermal decomposition of the complexes FeBr 3(na) 3·3H 2O( I), Fe 2O(Clpr) 4(na) 4·4H 2O( II) and Fe 3O(ac) 6(NO 3)(na) 5·Me 2CO( III), (where na=nicotinamide, Clpr=CH 3CHClCOO −, ac=CH 3COO − and Me=methyl). Characterization and chemical composition of the complexes were carried out using elemental analysis, complexometric titration and IR spectra. Schemes of thermal destruction of these complexes are suggested. Heating of these compounds first resulted in a release of solvent molecules. The thermal stability of these complexes can be ordered in the sequence: III<I= II. The thermal decomposition of the complexes produced FeO ( I) and Fe 2O 3 ( II and III) as the final solid products. Nicotinamide was coordinated to Fe(III) through the nitrogen atom of its heterocyclic ring. IR data suggested the bridging coordination and ionic bond of carboxylates in complex II and bridging coordination of carboxylates in complex III to Fe(III).

Induced Smectic-G Phase through Intermolecular Hydrogen Bonding, Part XII: Thermal and Phase Behaviour of p-aminobenzonitrile: p-n-alkoxybenzoic acids

New liquid crystalline compounds involving intermolecular hydrogen bonding between mesogenic p-n-alkoxybenzoic acids (nABA) (where n denotes the alkoxy carbon number varying from propylto decyl- and dodecyl-) and p-aminobenzonitrile (ABN) are synthesized. The thermal and phase behaviour of these materials is studied by Thermal Microscopy and Differential Scanning Calorimetry. Adetailed IR spectral investigation in solid and solution states confirms the formation of H-bonding between cyano and −COOH groups of ABN and nABA, respectively. Comparative thermal analyses of both free p-n alkoxybenzoic acids and H-bonded complexes suggest the induction of smectic-G phase in all the complexes.

Induced Smectic-G Phase through Intermolecular Hydrogen Bonding. Part VI: Thermal and phase Behavior of 2-(4-Decyloxybenzylidene Imino)-5-Chloropyridine (Dacp : Aba) Complexes

A novel series of liquid-crystalline complexes involving intermolecular hydrogen bonding between p - n -alkoxybenzoic acids (ABA) (where alkoxy = propoxy- to decyloxy- and dodecyloxy-) and 2-(4-decyloxybenzylidene imino)-5-chloropyridine (DACP) have been synthesized and their thermal and phase behaviour are studied by Thermal Microscopy (TM) and Differential Scanning Calorimetry (DSC). A detailed IR spectral investigation in solid and solution states confirms the formation of H-bonding between pyridine ring nitrogen and -COOH group of DACP and ABA respectively. Comparative thermal analyses of both free p - n -alkoxybenzoic acids and H-bonded complexes suggest the inducement of smectic-G phase in all the complexes, with a simultaneous quenching of smectic-C phase. The comparative thermal and phase behaviour with analogous series 2-(4-nonyloxybenzylidene imino)-5-chloropyridine : p - n -alkoxybenzoic acids (NACP : ABA) and 2-amino-5-chloropyridine : p - n -alkoxybenzoic acids (ACP : ABA) also imply the stabilization of the induced phase with a wide thermal span.

Subsolidus phase relations in the SnO2–CuSb2O6 binary system

Abstract The SnO 2 –CuSb 2 O 6 binary system plays a significant role in the SnO 2 –Sb 2 O 3 –CuO ternary system, delimiting the compositional ranges and their sensor and catalytic properties. The initial compositions expressed as (1− x ) SnO 2 – x CuSb 2 O 6 were treated both non-isothermally using DTA up to 1500 °C and iso-thermally at temperatures between 1000 and 1200 °C. Phase analysis of the samples was determined by XRD and IR spectroscopy. It was established that SnO 2 –CuSb 2 O 6 is a pseudobinary system with a solid solubility limit of the end members. The determined lattice parameters of the unit cell of the obtained rutile and trirutile solid solutions obeyed Vegard's rule. From IR spectral investigations it was inferred that Sn 4+ might be preferentially incorporated on Sb 5+ sites into the CuSb 2 O 6 lattice.

Induced crystal G phase through intermolecular hydrogen bonding VII. Influence of non-covalent interactions on mesomorphism and crystallization kinetics

A series of intermolecular hydrogen bonding complexes, 2,2'-bipyridine: p- n-alkoxybenzoic acids (BP : nABA) was isolated from liquid crystalline p-n-alkoxybenzoic acids (nABA) (where n represents alkoxy carbon numbers, 3 to 10 and 12) and a non-mesogen, 2,2'-bipyridine (BP). The thermal and phase behaviour of these complexes was studied by thermal microscopy and differential scanning calorimetry (DSC). These studies revealed the induction of tilted smectic F and crystal G phases. The structural elucidation pertaining to the formation of intermolecular hydrogen bonding was carried out by a detailed IR spectral investigation. Comparative crystallization kinectic studies using DSC, performed on two representative compounds, showed different forms of the crystallization process. The magnitudes of the Avrami exponent n suggests two different mechanisms operate for individual members leading to sporadic three-dimensional growth. Nevertheless, an overall unique mechanism is predicted to operate at each crystallization temperature investigated, while the Avrami constant b shows a temperature dependence suggesting a strong influence of alkoxy terminal groups on the rates of nucleation.

Induced Smectic-G Phase Through Intermolecular H-Bonding: Part III. Influence of Alkyl Chain Length of p-n-Alkoxybenzoic Acids on Thermal and Phase Behaviour

A novel series of intermolecular hydrogen bonding complexes have been synthesized by using p-n-alkoxybenzoic acids (alkyl chain length varies from propyl- to decyl and dodecyl-) (ABA) and a non-mesogenic moiety, 2-amino-5-chloro-pyridine (ACP), The thermal and phase behaviour of these complexes are studied by thermal microscopy (TM) and differential scanning calorimetry (DSC) techniques. The stabilization of intermolecular hydrogen bonding is studied by IR spectra. A detailed IR spectral investigation in solid and solution states suggest that both acid and pyridine nitrogens are complementary to one another by acting as proton donor and acceptor respectively. The comparative thermal studies with free benzoic acids and the corresponding analogous hydrogen bonded complexes reveal the inducement of a monotropic smectic-G phase with simultaneous quenching of nematic and smectic-C phases.

IR and UV Spectral Investigations of 2-Aminodiphenyldihydropyrimidines

IR and UV Spectral Investigations of 2-Aminodiphenyldihydropyrimidines

Thermochemistry of heteroatomic compounds. Part 13. The study of interaction between the esters of aminophosphonic and dithiophosphorus acids

Abstract The calculated thermodynamical data of complex formation between some derivatives of aminophosphonic and dithiophosphorus acids have been presented in this communication. The magnitudes of the formation enthalpy, Gibb's energy, entropy and equilibrium constant of the complex formation of the mentioned interaction in i-propanol-water mixture were determined. The carried out IR spectral investigations suggested the conclusion, which has been made on the basis of thermochemical research.

Thermoanalytical and IR-spectral Investigation of Mg(II) Complexes with Heterocyclic Ligands

Thermogravimetry (TG), differential thermal analysis (DTA) and other analytical methods have been applied to the investigation of the thermal behaviour and structure of the complexes Mg(pc)(na)3⋅3H2O (I), Mg(pc)(py)2⋅2H2O (II),Mg(pc)(pic)2⋅2H2O (III) and Mg(pc)(caf)2⋅4H2O (IV), where pc=2,6- pyridinedicarboxylate, na=nicotinamide,py=pyridine, pic=γ-picoline and caf=caffeine. The thermal decomposition of these compounds is multi-stage processes. The chemical composition of the complexes, the solid intermediates and the resultant products of thermolysis have been identified by means of elemental analysis and complexometric titration. Schemes of destruction of these complexes are suggested. Heating of these compounds first resulted in a release of water molecules. In complexes I, II and IV the loss of the molecular ligands (na, py and caf) occur (on the TG curves) in one step (-2na, -2py and -2caf) and in complex III in two steps (-pic, -pic). The final product of the thermal decomposition was MgO. The thermalstability of the complexes can be ordered in the sequence: IV<I<III<II. Nicotinamide, pyridine, γ-picoline and caffeine were co-ordinated to Mg(II) through the N atom of the respective heterocyclic ring. IR data suggested a unidentate co-ordination of carboxylates to Mg(II) in complexes I–IV.

Induced crystal G phase through intermolecular hydrogen bonding II. Influence of alkyl chain length of n-alkyl p-hydroxybenzoates on thermal and phase behaviour

A new series of intermolecular hydrogen-bonded complexes have been synthesized using p-n-alkoxybenzoic acid (alkyl chain length varies from propyl- to decyl- and dodecyl-) and methyl p-hydroxybenzoate moieties. The thermal and phase behaviour of these complexes were studied by thermal microscopy and differential scanning calorimetry. Further, the stabilization of intermolecular hydrogen bonding in solution was studied by IR spectroscopy. A detailed IR spectral investigation in the solid and dissolved states suggests that the acid and phenol groups act as proton donor and proton acceptor, respectively. The thermal studies also reveal the inducement of a crystal G phase in the complexes.

Synthesis and study by IR and UV methods of spectral analysis of a complex of Mo(VI) with quercetin

A complex of Mo(VI) with quercetin has been obtained. A hypothetical structure of the complex is proposed on the basis of IR and UV spectral investigations and elementary analysis.

Infrared microscopy and surface-enhanced Raman scattering of Ag colloid-2,2’-bipyridine film

A new methodology of IR spectral investigation of SERS-active surfaces was developed. IR microscopy in reflectance mode was employed for IR spectral mapping of a sample of Ag colloid-2,2’-bipyridine (bpy) film deposited on a substrate consisting of an 100nm Au layer sputtered onto a glass slide. IR spectra obtained from the film itself as well as from the yellow microcrystals observed in the boundary region of deposited film are consistent with the IR spectra of the crystals of a synthetically prepared [Ag(bpy)2]NO3 obtained by the same technique. The structure of the synthetically prepared complex was elucidated by X-ray diffraction. On the basis of the comparison between the IR and SERS spectral data, the time evolution of the SERS signal of adsorbed bpy is attributed to spectral changes induced by illumination of the sample by 514.5nm in the course of SERS spectral measurement.

Synthetic and spectral investigations of fluorinated 4 H-1,4-benzothiazines and their conversion into sulfones

The synthesis of fluorinated 4 H-1,4-benzothiazines and their conversion into sulfones is reported. The fluorinated 4 H-1,4-benzothiazines were prepared by the condensation and oxidative cyclization of 2-amino-3-chloro-5-fluorobenzenethiol with compounds containing active methylene groups in DMSO. The reaction is believed to proceed via an enaminoketone system. Fluorinated 4 H-1,4-benzothiazine sulfones have been synthesized by the oxidation of fluorinated 4 H-1,4-benzothiazines by 30% hydrogen peroxide in glacial acetic acid. IR, NMR and mass spectral investigations are included.

Sorption properties of technical lignins. III. IR-spectral investigation of the sorption capacity of technical lignins and their derivatives in relation to bile acids

It has been established by IR-spectral investigations that the sorption of bile acids by technical lignins takes place through the formation of hydrogen bonds between the functional groups of thelignins and the bile acids, the form of these bonds being determined by nature of the lignins and acids concerned.

Lanthanide(III) complexes with bidentate biheterocyclic ligands

Eight lanthanide thiocyanate complexes of the type [Ln(NCS) 3(PBH) 2] and [Ln(NCS) 3(MPB) 2], where Ln = La, Pr, Nd, Sm, Eu, Gd, Dy and Y and PBH and MPB are 2-(2-pyridylbenzimidazole) and 1-methyl-2-(2′-pyridyl)benzimidazole, respectively, have been synthesized and characterized by various physicochemical techniques such as conductance and thermogravimetric studies, electronic, IR, NMR ( 1H and 13C), EPR, CV and fluorescence spectral investigations. The v(CC) of the thiocyanate group indicates N coordination in all cases.

IR spectral investigation of the pyrolysis of polymer precursor to diamond-like carbon

Structural changes occurring during pyrolysis of the polymer [C 6H 5C] n (phenylcarbyne), synthesized by an ultrasonic chemical method, were investigated using IR spectra. IR absorption spectra in the wavenumber range 400–4600 cm −1 were measured and analyzed. Analysis of the spectral data indicated that OH, CH, CC, CO, COC stretching bonds etc. existed in the polymer, which suggested that the phenyl ring and impurities (water, methane, tetrahydrofuran, etc.) may be present in the polymer. The IR characteristics of the polymer showed a dependence on the temperature of pyrolysis. When the temperature was below 400°C, the powder was a hydrocarbon polymer with IR absorption indicating several kinds of bands similar to those of the original polymer; when the temperature was between 400 and 600°C, thermal decomposition of the polymer occurred, resulting in a reduction in intensity of various IR absorption bands; an increase in the temperature above 600°C resulted in the conversion to diamond-like carbon (DLC), showing only a few IR absorption bands (OH, CH, CC, CO). It is proposed that the structural changes of the polymer during pyrolysis were due to the evolution of the phenyl ring and impurities (hydrogen, etc.) in the polymer.

Glass formation and structure of glasses in the V2O5MoO3Bi2O3 system

The glass formation region in the V 2 O 5 MoO 3 Bi 2 O 3 system was investigated by the roller-quenching method. Low melting glasses were obtained in the MoO 3 - and V 2 O 5 -rich compositions. Characterization of the glasses was made by X-ray diffraction, differential thermal analysis (DTA) and IR spectroscopy. According to the DTA data, the glass transformation temperature, T g , for the different compositions varied between 200 and 290°C and the cystallization temperature, T X , was within the interval of 225–330°C. Structural models for glasses of th MoO 3 Bi 2 O 3 and V 2 O 5 Bi 2 O 3 systems were suggested on the basis of IR spectral investigations, by comparing with known crystalline structures. It was shown that the glasses possess [MoO 4 ], [MoO 6 ], [VO 4 ], and [BiO 6 ] groups as basic structural units.

Synthetic and spectral investigation of fluorinated phenothiazines and 4 H-1,4-benzothiazines as potent anticancer agents

The syntheses of fluorinated phenothiazines and fluorinated 1,4-benzothiazines are reported.Fluorinated phenothiazines have been prepared via a Smiles rearrangement of N-formylateddiphenylsulphides, synthesized in turn by condensation of substituted 2-aminobenzenethiolswith 2-chloro-5-trifluoromethylnitrobenzene followed by formylation with formic acid.Fluorinated 4 H-1,4-benzothiazines have been prepared by the condensation and oxidativecyclization of substituted 2-aminobenzenethiols with p-fluorobenzoylacetone in DMSO.The reaction is believed to proceed via an enaminoketone system. IR and NMR spectralinvestigations are included.