Chloranilic Acid Research Articles

Unprecedented strong intrinsic chemiluminescence generation from degradation of halogenated hydroxy-quinoid pollutants by Co(II)-mediated advanced oxidation processes: The critical role of site-specific production of hydroxyl radicals

We found previously that an unusual two-step hydroxyl radical (OH)–dependent chemiluminescence (CL) can be produced by the carcinogenic tetrachloro-1,4-benzoquinone (TCBQ, also known as p-chloranil) and H2O2. However, neither OH generation nor CL emission could be observed between H2O2 and chloranilic acid (CA), the dihydroxylation product of TCBQ. Here we found, unexpectedly, that distinct CL could be produced from CA/H2O2 in the presence of a variety of transition metal ions, among them Co(II) was found to be the most effective. Interestingly, the kinetic profiles of CL production, CA degradation, and reactive oxygen species (ROS) generation were found to be markedly changed with the molar ratios of Co(II):CA. When compared with the classic Fe(II)-mediated Fenton system, we found that the much stronger CL emission and more effective degradation of CA induced by Co(II)-mediated Fenton-like system is mainly due to the highly reactive OH generated site-specifically by Co(II)/H2O2, although other ROS such as O2− and 1O2 were also detected. More interestingly, not only CA, other halogenated anilic acids and catechols could also produce significant CL by Co(II)-mediated Fenton-like system. This is the first report on the distinct CL emission from degradation of halogenated hydroxyl-quinones by Co(II)-mediated Fenton-like advanced oxidation process, which is dependent on the site-specifically produced OH. These findings may have potential applications in measuring halogenated hydroxyl-quinones, and developing more effective techniques to degrade these types of important environmental pollutants.

Synthesis, characterization, antimicrobial and DNA binding properties of an organic charge transfer complex obtained from pyrazole and chloranilic acid

The chemistry of an organic charge transfer complex (CT complex) between pyrazole (donor) and chloranilic acid (acceptor) has been explored in ethanol at room temperature. The synthesized complex has been characterized by various techniques such as FTIR, NMR, Single crystal X-ray diffraction and UV-visible spectroscopy. These techniques indicate that the cation and anion are joined together by the weak hydrogen bonding. This molecular framework is a result of inter N+-H⋯O- bonding between donor and acceptor moieties. The elemental analysis and FTIR spectrum of semi-crystal complex along with Job's plot indicate the formation of 2: 1 HBCT-complex. The bioorganic chemistry of the present CT complex is established well toward antimicrobial screening and DNA binding capabilities. Antimicrobial activity was screened for gram positive and gram negative bacteria and various fungi. Molecular docking shows that the CT complex binds perfectly with the B-DNA and reveals free energy of binding (FEB) value of -198.4kcalmol-1. TD-DFT calculations using basis set B3LYP/6-311G** give theoretical confirmation along with HOMO (-3.9421eV)→LUMO (-2.4903eV) electronic energy gap (ΔE) to be 1.4521eV. Theoretical analysis corroborates well the biological properties.

SPECTROPHOTOMETRIC DETERMINATION OF DASATINIB IN PHARMACEUTICAL FORMULATIONS

Objective: A new, simple, sensitive, precise and reproducible bioanalytical method was developed for the determination of Dasatinib in pharmaceutical formulations with Chloranilic acid.
 Methods: The method is based on formation of violet colored complex. The UV spectrum of Dasatinib in methanol showed λ max at 521 nm. Beer’s law is valid in the concentration range of 10-60 μg/ml. This method was validated for linearity, accuracy, precision, ruggedness and robustness.
 Results: The method has demonstrated excellent linearity over the range of 10-60 μg/ml with regression equation y = 0.021x-0.083 and regression correlation coefficient r2= 0.997. Moreover, the method was found to be highly sensitive with LOD (2.96μg/ml) and LOQ (8.98μg/ml).
 Conclusion: Based on results the proposed method can be successfully applied for the assay of Dasatinib in various pharmaceutical dosageforms.

Spectroscopic Characterization, Molecular Modeling and DFT/TD-DFT/PCM Calculations of Novel Hydrogen-Bonded Charge Transfer Complex between Chloranilic Acid and 2-Amino-4,6-Dimethylpyridine

A charge transfer hydrogen bonded complex between the electron donor (proton acceptor) 2-amino-4,6-dimethylpyridine with the electron acceptor (proton donor) chloranilic acid has been synthesized and studied experimentally and theoretically. The stability constant recorded high values indicating the high stability of the formed complex. In chloroform, ethanol, methanol and acetonitrile were found the stoichiometric ratio 1:1. The solid complex was prepared and characterized by different spectroscopy techniques. FTIR, 1H and 13C NMR studies supported the presence of proton and charge transfers in the formed complex. Complemented with experimental results, molecular modelling using the density functional theory (DFT) calculations was carried out in the gas, chloroform and methanol phases where the existence of charge and hydrogen transfers. Finally, a good consistency between experimental and theoretical calculations was found confirming that the applied basis set is the suitable one for the system under investigation.

Thermodynamic Study and Spectroscopic Analysis of a Charge-Transfer Complex between 3,5-Diamino-1,2,4-Triazole and 6-Methyl-1,3,5-Triazine-2,4-Diamine with Chloranilic Acid

Studying of charge-transfer (CT) and proton transfer interactions is essential due to their important role in many biological field and industrial applications. The current work will add more information’s about the nature of interaction between 3,5-diamino-1,2,4-triazole (DAT) and 6-methyl-1,3,5-triazine-2,4-diamine (MTDA) with 3,6-dichloro-2,5-dihydroxy-p-benzoquinone (chloranilic acid CLA) which was studied spectrophotometrically in Ethanol (EtOH) and Methanol (MeOH) solvents at different temperatures. The molecular composition of the formed complexes was studied by applying continuous variation and spectrophotometric titration methods and found to be 1:1 charge transfer complex for both Complex (DAT:CLA) and (MTDA:CLA) which are produced. Minimum-Maximum absorbance’s method has been applied to calculate the formation constant KCT and molecular extinction coefficient (ε); they recorded high values confirming high stability of the produced complexes. Oscillator strength (f), transition dipole moment (μ), ionization potential (IP) and dissociation energy (W) of the formed CT-complexes were also determined and evaluated; they showed solvent dependency. It is concluded that the formation constant (KCT) of the complexes is found to depend on the nature of both electron acceptor and donors and on the polarity of solvents.

Crystal structures of organic salts of chloranilic acid and 2,2′-bi(3-hydroxy-1,4-naphthoquinone) acting as proton donors to 4,4′-Bipyridine and 1,4-Diazabicyclo[2.2.2]octane: 3D networks with bifurcated N+-H···O−/O or N+-H···O/Cl synthons

Five organic salts were prepared by proton transfer from organic acids to nitrogenous bases using chloranilic acid (H2CLA) or the Lawsone dimer (H2LD) as proton donors and 1,4-diazabicyclo[2.2.2]octane (DABCO) or 4,4′-bipyridine (BPY) as proton acceptors, viz., [(H2BPY)(CLA)]⋅4H2O, [(HDABCO)2(CLA)]⋅2H2O, [(HDABCO)2(CLA)]⋅6H2O, [(H2DABCO)(HCLA)2]⋅2H2O, and [(H2DABCO)(LD)]⋅H2O. The molecular crystal salts were characterized by elemental analysis, single-crystal X-ray diffraction (SCXRD) analysis, infrared spectroscopy and TG-DSC measurements. The SCXRD studies revealed that the molecular crystals studied herein are all hydrates with extensive and diverse hydrogen bonds of the N+−H⋅⋅⋅O−/O, N+−H⋅⋅⋅O/Cl, Ow−H⋅⋅⋅O−/O, Ow−H⋅⋅⋅Cl, Ow−H⋅⋅⋅N, Ow−H⋅⋅⋅Ow, and C–H⋅⋅⋅N type, which in some cases were accomplished by π–π, Cl⋅⋅⋅Cl or Cl⋅⋅⋅O contacts. Common to all crystal structures is the presence of cation-anion aggregates formed through bifurcated N+−H⋅⋅⋅O−/O or N+−H⋅⋅⋅O/Cl hydrogen bonds. All compounds constitute infinite 3D supramolecular networks based essentially on hydrogen bonding or a combination of hydrogen bonding and π-π interactions.In addition, ecofriendly preparative methods were tested for the preparation of the organic molecular crystal salts studied herein, viz., neat grinding, liquid-assisted grinding, slurry and precipitation.

Synthesis, spectroscopic, theoretical and antimicrobial studies on molecular charge-transfer complex of 4-(2-thiazolylazo)resorcinol (TAR) with 3, 5-dinitrosalicylic acid, picric acid, and chloranilic acid

Charge-transfer complex of 4-(2-thiazolylazo) resorcinol (TAR) with 3, 5-dinitrosalicylic acid (3,5-DNSA), picric acid (PA), and chloranilic acid (CLA) were synthesized and characterized spectroscopically and investigated theoretically. Molecular composition of the prepared complexes was determined by mole ratio method. It was found that the stoichiometry of all prepared complexes is 1:2 (donor: acceptor) in methanol solvent. Stability constant of the prepared complexes were determined by using modified Benesi-Hildebrand equation. High values of formation constant of the complexes were signifying the high stability of the complexes. Different spectroscopic parameter as ionization potential (ID) of donor, oscillator strength (f), transition dipole moment (μEN), etc. were determined using UV–Vis spectroscopy in same solvent. The effect of solvent polarity on the charge-transfer spectra was also verified in four different solvents. The infrared spectrum studies of the solid complexes explore the presence of charge-transfer interaction through a hydrogen bonding interaction. TGA-DTA of the prepared complexes was also done to find out the thermal nature and stability of the complex. Synthesized complexes were checked for antibacterial and antifungal activities against different bacterial and fungal strains and complexes shows potent antibacterial and antifungal activity. DFT method was employed to view the molecular structure, electronic and spectroscopic nature of the studied complexes. MEP calculation, HOMO and LUMO energies, interaction energy, NBO analysis were performed on optimized structures of the complexes.

Spectroscopic investigation of π-acceptors in the determination and photoinduced degradation of Sulfacetamide.

The presence of expired and unused Sulfacetamide (SA) drug in water led to a global need for the development of effective advanced method for the quantitative analysis and for minimizing its occurrence in the nature. To find new effective photochemical decomposition method close to that obtained by the well-known Fenton reaction, the photodegradation of SA was investigated in presence of dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and/or other common additives at two different wavelengths (365 and 256nm). The role of DDQ in the degradation process of SA was evaluated in comparison to the other investigated π-acceptor systems (Chloranilic acid (CHL) and Picric acid (PA)). While the photodegradation process of SA was hardly to proceed in the absence of a catalyst and/or additive, addition of DDQ and NaNO2 to the solution of SA induced decomposition of about 94% of SA within 25min upon the exposure to light source at 256nm. On the other hand, SA was quantitatively analyzed by recording the absorbance of its charge transfer (CT) products with DDQ, CHL and PA at a certain wavelength. CHL is preferred with concentrated samples of SA, while PA is recommended for diluted samples of SA. SA→DDQ has a widely range of stability over the pH range of 4.5-12.0. While SA→CHL is stable only in the acidic medium (pH=4.8-5.6), SA→PA is steady in the basic medium (pH=7.5-11.0). The nature of the DDQ CT complex was investigated in the solid state. The electronic structures of the complexes were studied by calculating the time dependent density functional theory (TDDFT) spectra.

Binuclear Oxidovanadium(IV) Complex with the Bridging Chloranilate Ligand: Synthesis and Magnetic Properties

The binuclear oxidovanadium(IV) complex [VO(Dbbpy)Cl(Ca)Cl(Dbbpy)VO] (I) is synthesized by the reaction of [VO(Dbbpy)(H2O)Cl2] (Dbbpy is 4,4'-di-tert-butyl-2,2'-bipyridyl) with chloranilic acid H2Ca in acetonitrile in the presence of Et3N in a yield of 79%. Complex I is reduced at Е1/2 = –842 mV (vs. Ag/AgCl), which is shown by cyclic voltammetry for a solid sample using the paste electrode. The EPR spectra and magnetochemical measurements for complex I confirm the existence of two paramagnetic vanadium(IV) centers with the total spin S = 1 and the antiferromagnetic character of the exchange interaction between the centers.

Chemical and biological studies on charge-transfer complexes of cimetidine with various electron acceptors

Abstract Interaction of Cimetidine drug (CIM) with π-acceptors as Tetracyanoethylene (TCNE) and 7,7′,8,8′-Tetracyanoquinodimethane (TCNQ), chloranilic acid (H2CA) picric acid (HPA) resulted through the initial formation of ionic intermediate to charge transfer (CT) complex which detected by spectroscopic studies. The molar ratio was found to be 1:1 between cimetidine drug and different acceptor. The formed CT complexes have been characterized using various techniques such as the elemental analyses, UV–Vis., IR, and 1H NMR spectra, and thermal analyses (TG, DTG). The antibacterial activity of the complexes were estimated.

A simple RGB-type chromogenic sensor based on color modulation of chloranilic acid for moisture determination of alcohols

A simple RGB-type chromogenic sensor based on color modulation of chloranilic acid for moisture determination of alcohols

X-ray crystal structure, spectroscopic and DFT computational studies of H-bonded charge transfer complexes of tris (hydroxymethyl)aminomethane (THAM) with chloranilic acid (CLA)

The crystal and molecular structures of two new synthesized charge transfer complexes produced from the reaction of tris(hydroxymethyl)aminomethane, THAM and 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid, CLA) in the mole ratios (2:1) [I] and (1:1) [II], have been studied. The; FT-IR and 1H NMR spectral data of the complexes are confirmed by single-crystal X-ray crystallography. The single-crystal X-ray crystallography, indicated the formation of both inter- and intra-molecular hydrogen bonding as well as the proton transfer from CLA to THAM. The electronic transition spectra of these two complexes as acetonitrile (AN), methanol (MeOH), ethanol (EtOH) solutions are recorded. The molecular compositions of the formed complexes in the three solvents determined by Job's method, support 1:1 mol ratio complex, whatever the polarity of the solvent. The high values of charge transfer complex formation constants, KCT determined by applying the minimum–maximum absorbance method, indicated the formation of stable CT-complexes, with the order Ethanol > Methanol ≫ Acetonitrile. Computational study incorporated the use of TD-DFT with PCM as solvation model are applied for energy minimization and estimation of the stabilization energy for the produced complexes. The geometrical parameters (bond lengths and angles) of the formed CT complexes are computed and analyzed. Furthermore, Mulliken atomic charges, molecular potential energy surface, HOMO and LUMO molecular orbitals of the formed complexes are presented. A good agreement between experimental and DFT computational analysis has been found.

A Strategic High Yield Synthesis of 2,5-Dihydroxy-1,4-benzoquinone Based MOFs.

Metal organic frameworks (MOFs) of the type NBu4M(DHBQ)1.5 (M = Ni2+, Fe2+, and Co2+; DHBQ = 2,5-dihydroxy-1,4-benzoquinone) were prepared with improved yield up to 100% via a simple benchtop aqueous addition reaction. For the first time, the crystalline phase of this formula polymer was synthesized without in situ generation of the DHBQ ligand from 2, 5-diamino-1,4-benzoquinone (DABQ). Powder X-ray diffraction and elemental analysis confirm the crystalline phase and composition of products. Infrared and electron dispersive spectroscopy further confirm that the materials are homologous to the reported single crystalline polymers. The present MOF synthesis can be extended to halide-substituted ligands, i.e., 3,6-dichloro-2,5-dihydroxy-1,4-benzoquinone (chloranilic acid, CAN) and 3,6-difluoro-2,5-dihydroxy-1,4-benzoquinone (fluoranilic acid, FAN).

Accessing New Charge-Transfer Complexes by Mechanochemistry: A Tetrathiafulvalene Chloranilic Acid Polymorph Containing Segregated Tetrathiafulvalene Stacks

Two polymorphs of tetrathiafulvalene chloranilic acid (TTF-CAH2) have been synthesized by mechanochemistry. The previously known "ionic" polymorph (form I) was prepared by liquid-assisted grinding (LAG) using various highly polar solvents as well as protic but moderately polar solvents, such as alcohols of one to four carbon atoms. A new TTF-CAH2 polymorph (form II) was obtained by LAG and slurry mechanochemistry using aprotic, low-polarity solvents, as well as nonpolar solvents and neat grinding. The crystal structure of the new TTF-CAH2 polymorph was determined from the combined analysis of synchrotron powder X-ray diffraction and neutron powder diffraction data at room temperature. The material displays segregated stacks of TTF and CAH2 molecules. Fourier transform infrared spectroscopy as a function of the temperature (10-300 K) indicates that TTF-CAH2 form II is an electrical semiconductor with a small band gap of ∼0.115 eV (versus ∼0.146 eV for the "ionic" form I), and there is no indication of phase transitions in that temperature interval. The examination of the frequency regions wherein the absorption bands of TTF and TTF+• species occur suggests that TTF-CAH2 form II is most likely a neutral phase.

Synthesis, spectroscopic characterization and structural investigation of new charge-transfer complexes of piroxicam with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and chloranilic acid: Experimental and theoretical studies

Synthesis, spectroscopic characterization and structural investigation of new charge-transfer complexes of piroxicam with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and chloranilic acid: Experimental and theoretical studies

Charge transfer complexes of brucine with chloranilic acid, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and tetracyanoquinodimethane: Synthesis, spectroscopic characterization and antimicrobial activity

Three new charge transfer (CT) complexes consisting of brucine (Bru) as the electron donor and chloranilic acid (ChA), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) or 7,7,8,8-tetracyanoquinodimethane (TCNQ) as the electron acceptors were synthesized. These complexes were characterized using different analytical tools, nuclear magnetic resonance (NMR), infrared spectroscopy (IR) and mass spectrometry (MS). Spectroscopic studies were carried out to estimate different physical parameters, such as resonance energy, oscillator strength, transition dipole moment, ionization potential, energy of interaction, molar extinction coefficient and free energy.Stoichiometry in liquid was determined by applying Job's method, and a 1:1 ratio was found in line with the results of the Benesi-Hildebrand equation. The determination of brucine with good reliability was carried out using CT complexes formation. Data analysis demonstrated the formation of the CT complexes and their antimicrobial activity was investigated; the screening data acquired herein show a potential antimicrobial effect superior to the brucine by itself.

Characterization of charge transfer products obtained from the reaction of the sedative-hypnotic drug barbital with chloranilic acid, chloranil, TCNQ and DBQ organic acceptors

The barbital (Bar) is one of the barbituric acid derivatives. It possesses a potent sedative-hypnotic property. Structural, thermal and morphological properties of the charge transfer (CT) products obtained from the reaction of barbital (Bar) with chloranilic acid (CLA), chloranil (CHL), TCNQ and DBQ π-acceptors were reported. The products were prepared in methanol media, isolated and fully characterized spectroscopically, thermally and morphologically using IR, 1H NMR, Raman, UV–Vis., TG, XRD and SEM techniques. Experimental results obtained by spectroscopic titrations and elemental analysis suggested that the reaction stoichiometry is 1:1, and the synthesized products were [(Bar)(CLA)], [(Bar)(CHL)], [(Bar)(TCNQ)], and [(Bar)(DBQ)]. The complexation of Bar with CHL, TCNQ and DBQ acceptor was taking place through n→π* interaction, while its complexation with CLA acceptor was taking place by the formation of intermolecular hydrogen bond. Formation of the products was thermally stable as indicated by the TG analysis. SEM and XRD analyses indicate that the products possess uniform microstructures with well-organized nano-sized particles having a main diameter in the range around ~50nm.

CHARGE-TRANSFER COMPLEXES OF CHLORPHENOXAMINE HYDROCHLORIDE WITH CHLORANILIC ACID, 2,3-DICHLORO-5,6-DICYANO-1,4-BENZOQUINONE AND 7,7,8,8-TETRACYANOQUINODIMETHANE AS π-ACCEPTORS

Objective: To develop simplified, accurate and precise visible spectrophotometric strategies for the assay of chlorphenoxamine hydrochloride (CPX) in pure drug and in its pharmaceutical preparations.
 Methods: The described methods depended on the formation of charge-transfer (CT) complexes of intense color between CPX as donor with three π-acceptors, chloranilic acid (CLA), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), and 7,7,8,8-tetracyanoquinodimethane (TCNQ) and the colored reaction products were estimated spectrophotometrically at 520 nm, 460 nm and 840 nm for CLA, DDQ, and TCNQ complexes, individually. All the optimum conditions were established. The proposed methods were validated in term of linearity, limit of detection as per the international conference on harmonization guidelines ICH Q2 (R1).
 Results: The complexes obeyed Beer’s law in the concentration range of 16-144, 6-54 and 4-76 μg/mlwith molar absorptivity at 0.30×104, 0.68×104 and 0.58×104 l/mol/cm for CLA, DDQ, and TCNQ, individually. According to Benesi-Hildebrand plots, the association constants and changes of standard free energy were determined. 1:1 was the ratio of composition of the formed CT-complex.
 Conclusion: The obtained results revealed that the developed method can be applied successfully for the determination of CPX in drug formulations samples with good accuracy and precision.

Novel charge transfer-hydrogen bonded complex between 2-amino-4,6-dimethoxy-pyrimidine (ADMP) with chloranilic acid (H2CA): temperature, solvation and DFT computational studies

ABSTRACTNew charge transfer complex associated with hydrogen bonding between 2-amino-4,6-dimethoxypyrimidine (ADMP) with chloranilic acid (H2CA) was studied in solution and solid state. The solution studies were carried out in three polar solvents ethanol (EtOH), methanol (MeOH) and acetonitrile (ACN). The formed complex exhibited new absorption maxima above 500 nm. The molecular composition was done by job and photometric titration methods where the complex proceeded through 1:1 ratio. Moreover, the stability constant was calculated by Bensie-Hildebrand equation, the highest value was in methanol and least one in ethanol. The solid complex was synthesised and characterised by elemental analysis and infrared spectra, and they confirmed the formation of 2:1 (donor: acceptor) complex and its structure included charge transfer besides hydrogen bonding. DFT computations using the hybrid method B3LYP-DFT at the basis set 6-31G(d,p) were running out in gas phase to support the mechanism of complex formation in solid state.

Malleable Electronic Structure of Chloranilic Acid and Its Species Determined by X-ray Charge Density Studies

Herein, we present a detailed X-ray charge density study of the electron delocalization in five species of chloranilic acid: neutral molecule, mono- and dianion, and two chelating modes: bidendate and (bis)bidentate. The experiments provide the electron density at the bond critical points, which yields an accurate measure of bond order (and therefore electron delocalization), and complement previous literature and our data on bond lengths extracted from crystal structures and infrared spectra. Mapping of the electrostatic potential indicates electron-rich and electron-poor areas in the molecule, corresponding to single (electron-poor), double, and delocalized bonds (electron-rich) that can explain stacking interactions of quinoid rings in crystal packing.