Chloranilic Acid Research Articles

Facile Charge Transfer between Barbituric Acid and Chloranilic Acid over g-C3N4: Synthesis, Characterization and DFT Study

The molecular complexes between barbituric acid (BU) and chloranilic acid (ChA) over graphitic nitride (g-C3N4) are investigated. The molecular complexes and the nanocomposite were investigated both in solid state and in methanol. The solid complexes and the corresponding nanocomposite were investigated using FTIR, TGA, and UV-Vis spectroscopy. The structures were explored using DFT calculations using wB97XD/ and def2-TZVP basis set. The DFT calculations revealed the formation of hydrogen-bonded complexes, which initiate the proton transfer from ChA to BU. Immobilization of the BUChA complex over the g-C3N4 sheet was stabilized by weak non-covalent interactions, such as π–π interactions. g-C3N4 facilitated the charge transfer process, which is beneficial for different applications.

Selective Construction of Trefoil knots and a Molecular Borromean Ring Induced by Steric Hindrance of Thioether Ligands.

Two Cp*-RhIII based trefoil knots were obtained in high yield under ambient conditions via the coordination-driven self-assembly of semi-rigid thioether dipyridyl ligand 1,4-bis[(pyridin-4-ylthio)methyl]benzene (L1 ), ligand chloranilic acid (H2 -CA) and 6,11-dihydroxytetracene-5,12-dione (H2 -TtDo) with Cp*RhIII metal corner units, respectively. Furthermore, using the bulkier 4,4'-{[(2,5-dimethyl-1,4-phenylene)bis(methylene)]bis(sulfanediyl)}dipyridine (L2 ) in the place of ligand L1 in the construction process resulted in the formation of a teranuclear metallacycle and a template-free Borromean ring in high yields thanks to significantly altered intermolecular forces between the constituent ligands induced by the sterically-hindering methyl groups of L2 , as demonstrated via a detailed X-ray crystallographic analysis and NMR spectroscopy.

Interplay between Electronic, Magnetic, and Transport Properties in Metal Organic–Radical Frameworks

Development of modern electronic and spintronic technologies depends in large part on the ability to design materials exhibiting switchable magnetic and electrical properties. Here, motivated by the successful demonstration of reversible redox switching of magnetic order and electrical conductivity in 2dimensional metal-organic frameworks (MOFs) based on benzoquinoid linkers, we perform hybrid density functional theory calculations to investigate this phenomenon at the atomistic level. Electronic, magnetic and charge transport properties have been systematically investigated for oxidized and reduced forms of Mn and Fe benzoquinoid frameworks (i.e., (Me 4 N) 2 [Mn 2 L 3 ], (Me 4 N) 2 [Fe 2 L 3 ] and Na 3 (Me 4 N) 2 [Mn 2 L 3 ], Na(Me 4 N) 2 [Fe 2 L 3 ], respectively with deprotonated chloranilic acid as L). We demonstrate that the experimentally observed large increase in electronic conductivity upon ligand-centered reduction in the Mn MOF (10 9 S•cm −1), is due to cooperative effects arising from band gap reduction and the presence of electrons with lower effective mass. Superior conductivity (by at least 3 orders of magnitude) of the redox pair of the Fe benzoquinoid framework as compared to the Mn analog stems from similar factors and, notably, a large increase in electron delocalization for the reduced Fe compound.

Heteroleptic LaIII Anilate/Dicarboxylate Based Neutral 3D-Coordination Polymers.

Three new 3D metal–organic frameworks of lanthanum based on mixed anionic ligands, [(La2(pQ)2(BDC)4)·4DMF]n, [(La2(pQ)2(DHBDC)4)·4DMF]n, [(La2(CA)2(BDC)4)·4DMF]n (pQ—dianion of 2,5-dihydroxy-3,6-di-tert-butyl-para-quinone, CA—dianion of chloranilic acid, BDC-1,4-benzenedicarboxylate, DHBDC-2,5-dihydroxy-1,4-benzenedicarboxylate and DMF-N,N′-dimethylformamide), were synthesized using solvothermal methodology. Coordination polymers demonstrate the rare xah or 4,6T187 topology of a 3D framework. The homoleptic 2D-coordination polymer [(La2(pQ)3)·4DMF]n was obtained as a by-product in the course of synthetic procedure optimization. The thermal stability, spectral characteristics and porosity of coordination polymers were investigated.

Incorporating porphyrin-Pt in light-harvesting metal-organic frameworks for enhanced visible light-driven hydrogen production

Molecular catalysts for H2-evolution are of interest for their integration into light-harvesting complexes for photocatalytic water splitting. Here, we report the meso-tetra (4-carboxyphenyl) porphine [(TCPP)PtII] complex as a molecular H2-evolving photocatalyst using chloranilic acid (CA) as a sacrificial electron donor, the choice of which is critical to the stability of the photocatalyst. When triethanolamine was used, [(TCPP)PtII] decomposed to form Pt nanoparticles. Density functional theory calculations together with evidence from electrochemical and spectroscopic analyses suggested that the catalysis was possibly initiated by a proton-coupled electron transfer (PCET) to form [(TCPP)PtI]-N-H, followed by another electron injection and protonation to form a [(TCPP)PtII-hydride]-N-H intermediate that can release H2. As the whole catalytic cycle involves the injection of multiple electrons, a light-harvesting network should be helpful by providing multiple photo-induced electrons. Thus, we integrated this molecular catalyst into a light-harvesting metal-organic framework to boost its activity by ~830 times. This work presents a mechanistic study of the photocatalytic H2 evolution and energy transfer and highlights the importance of a light-harvesting network for multiple electron injections.

Correlations between spectroscopic data for charge-transfer complexes of two artificial sweeteners, aspartame and neotame, generated with several π-acceptors

Charge-transfer (CT) interaction of two artificial sweeteners, aspartame (Asp) and neotame (Neo), with three organic π-acceptors was investigated by UV–visible and Infrared (IR) spectrophotometric measurements. The target sweeteners interacted with the 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), chloranilic acid (CA), and picric acid (PA) molecules in methanol solvent at room temperature. Spectral results suggest that the unshared electron pair of nitrogen atoms (-NH2 in Asp molecule, and -NH in Neo molecule) donate electronic charge to the aromatic ring of the acceptor (Asp→acceptor; Neo → acceptor) forming the CT complex via a n → π* transition. The 1:1 Benesi-Hildebrand method was used to calculate several spectroscopic data, such as the formation constant (KCT) and the molar extinction coefficient (εmax), and other physical parameters. The correlation test indicates strong relationships among several of the physical parameters.

Exploring the charge-transfer chemistry of fluorine-containing pyrazolin-5-ones: The complexation of 1-methyl-3-trifluoromethyl-2-pyrazoline-5-one with five π-acceptors

Pyrazole derivatives play an important role in medicinal chemistry. In this study, we investigated the charge-transfer (CT) chemistry of one of these derivatives, 1-methyl-3-trifluoromethyl-2-pyrazoline-5-one, referred to as FP. This target compound was interacted with five π-acceptors; picric acid, chloranilic acid, fluoranil, DDQ, and TCNQ in methanol. The elemental and spectral results indicate that the synthesized CT complexes formed with 1:1 FP to acceptor stoichiometry in an exothermic, spontaneous reaction via an n → π* transition (FP → acceptor) into stable, colored products. Physical parameters such as the molar extinction coefficient (εmax), formation constant (KCT), and other spectroscopic data were calculated using the 1:1 Benesi-Hildebrand method. Pearson's correlation coefficient analysis revealed strong statistically significant correlations between several of the spectroscopic parameters.

Mechanistic Study on Chemiluminescence of Chloranilic Acid by Co(II)-Mediated Fenton-like System.

Reacting with H2O2, tetrachloro-1,4-benzoquinone (TCBQ) produces chemiluminescence (CL), but chloranilic acid (CA), the dihydroxylation product of TCBQ, does not. However, an unprecedented strong CL generates from CA/H2O2 in the presence of Co(II). Why? We performed quantum chemical calculations on the entire reaction process of CA/H2O2 and CA/H2O2/Co(II) systems. The computational results indicate: for CA/H2O2 system, the reason leading to non-CL as: there is no free •OH produced by CA/H2O2, which prevents the subsequent reaction from taking place; for CA/H2O2/Co(II) system, the chemical process resulting in the CL as: First, a neutral dioxetane is formed via six sequential reactions. Then, the neutral dioxetane decomposes to generate a neutral excited-state (S1) product via a gradually reversible charge transfer initiated luminescence mechanism. A conical intersection of the ground and the S1-state potential energy surfaces facilitates the production of the S1-state product. Ultimately, the neutral S1-state product emits light as a practical light emitter. The key component for forming dioxetane and the following CL is the intrinsically generated •OH, which is roaming around at the region of C2 atoms of the CA moiety, instead of being free. The quantum chemical calculations supported the experimental observation and conclusion by providing the mechanistic explanation in detail.

Gliclazide charge transfer complexes with some benzoquinone acceptors: Synthesis, structural characterization, thermal analyses, DFT studies, evaluation of anticancer activity and utility for determination of gliclazide in pure and dosage forms

The reaction between gliclazide (GLZ, the antidiabetic drug) as n-electron donor with 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid, PCA) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as π-acceptors led to the formation of 1:1 charge-transfer (CT) complexes as the final products. These reactions were utilized for the spectrophotometric quantitative determination of GLZ in its pure and pharmaceutical forms (diamicron and diamedizen tablets) under various optimized conditions and a good linearity was obtained with a wide range of concentrations of 10-450 and 30-500 µg mL−1 using DDQ and PCA reagents, respectively. The limits of detection and quantification, inter-day and intra-day accuracy and precision were optimized. The formed complexes were structurally characterized using different spectral methods. Theoretical DFT/TD-DFT calculations were performed to investigate their optimized geometries, molecular electrostatic potentials (MESP), quantum chemical parameters and electronic spectra. Thermal properties of the formed CT complexes were studied and their anticancer activity were screened against breast cancer MCF-7 cell line.

Experimental and Computational Evaluation of Chloranilic Acid as an Universal Chromogenic Reagent for the Development of a Novel 96-Microwell Spectrophotometric Assay for Tyrosine Kinase Inhibitors.

The tyrosine kinase inhibitors (TKIs) are chemotherapeutic drugs used for the targeted therapy of various types of cancer. This work discusses the experimental and computational evaluation of chloranilic acid (CLA) as a universal chromogenic reagent for developing a novel 96-microwell spectrophotometric assay (MW-SPA) for TKIs. The reaction resulted in an instantaneous formation of intensely purple colored products with TKIs. Spectrophotometric results confirmed that the reactions proceeded via the formation of charge-transfer complexes (CTCs). The physical parameters were determined for the CTCs of all TKIs. Computational calculations and molecular modelling for the CTCs were conducted, and the site(s) of interaction on each TKI molecule were determined. Under the optimized conditions, Beer’s law correlating the absorbances of the CTCs with the concentrations of TKIs were obeyed in the range of 10–500 µg/well with good correlation coefficients (0.9993–0.9998). The proposed MW-SPA fully validated and successfully applied for the determination of all TKIs in their bulk forms and pharmaceutical formulations (tablets). The proposed MW-SPA is the first assay that can analyze all the TKIs on a single assay system without modifications in the detection wavelength. The advantages of the proposed MW-SPA are simple, economic and, more importantly, have high throughput.

Spectrophotometric and computational investigations of charge transfer complexes of chloranilic acid with tyrosine kinase inhibitors and application to development of novel universal 96-microwell assay for their determination in pharmaceutical formulations

The tyrosine kinase inhibitors (TKIs) are chemotherapeutic drugs used for targeted therapy of various types of cancer. In literature, there is no existing universal chromogenic reagent used for development of spectrophotometric assay for all TKIs regardless the diversity of their chemical structures. This work discusses, for the first time, the experimental and computational evaluation of chloranilic acid (CLA) as a universal chromogenic reagent for developing a novel 96-microwell spectrophotometric assay (MW-SPA) for TKIs. The reaction of CLA with seven TKIs was examined in different organic solvents of various dielectric constants and polarity indexes. The reaction resulted in an instantaneous formation of intensely purple coloured products with all the investigated TKIs. Spectrophotometric investigations confirmed that the reactions proceeded via the formation of charge-transfer complexes (CTC). The physical parameters (molar absorptivity, molar ratio, association constant and standard free energy) were determined for the CTC of all TKIs. Computational calculations for the relative electron densities on each atom of the TKI molecule and molecular modelling for the CTC were conducted, and the site(s) of interaction on each TKI molecule were determined. Under the optimized conditions, Beer’s law correlating the absorbances of the CTC with the concentrations of TKIs were obeyed in the range of 5–500 µg/well with good correlation coefficients (0.9991–0.9998). The limits of detection and quantitation were in the ranges of 1.89–5.09 and 5.74–15.42 µg/well, respectively. The proposed MW-SPA showed high precisions as the values of the relative standard deviations did not exceed 2.01 and 2.45% for the intra- and inter-assay precision, respectively. The accuracy of MW-SPA was proved by recovery studies as the recovery values were in the range of 98.8–103.7%. The proposed MW-SPA was successfully applied for the determination of all TKIs in their bulk forms and pharmaceutical formulations (tablets) with good accuracy and precisions. The proposed MW-SPA is the first assay that can analyse all the TKIs on a single assay system without modifications in the detection wavelength. Additional advantages of the proposed MW-SPA are simple, economic, and more importantly have high throughput. Therefore, the assay can be helpful and beneficial for routine analysis of TKIs in their pharmaceutical formulations in quality control laboratories.

Exploring the charge transfer dynamics of hydrogen bonded crystals of 2-methyl-8-quinolinol and chloranilic acid: synthesis, spectrophotometric, single-crystal, DFT/PCM analysis, antimicrobial, and DNA binding studies.

The new chemistry of the hydrogen-bonded charge and proton transfer complex (HB CT) between electron-donor 2-methyl-8-quinolinol (2 MQ) and electron-acceptor chloranilic acid (CHLA) has been studied using electronic absorption spectroscopy in acetonitrile (ACN), methanol (MeOH), and ethanol (EtOH) polar media at room temperature. The stoichiometric proportion of the HB CT complex was observed to be 1 : 1 from the Job data and photometric titration process. The association constant (KCT) and molar absorptivity (εCT) of the HB CT complex were determined by using the modified Benesi–Hildebrand equation in three polarities. Other spectroscopic physical parameters like the energy of interaction (ECT), ionization potential (ID), resonance energy (RN), standard free energy change (ΔG°), oscillator strength (f), and transition dipole moment (μ) were also evaluated. The HB CT complex structure was confirmed by different characterization techniques, such as FT-IR, NMR, TGA-DTA, and SEM-EDX analysis. Powder XRD and single-crystal XRD were used to determine the nature and structure of the synthesized HB CT complex. DNA binding studies for the HB CT complex produced a good binding constant value of 2.25 × 104 L mol−1 in UV-visible and 1.17 × 104 L mol−1 in fluorescence spectroscopy. The biological activity of the HB CT complex was also tested in vitro against the growth of bacteria and fungi, and the results indicated remarkable activity for the HB CT complex compared to the standard drugs, ampicillin and clindamycin. Hence, the abovementioned biological results of the synthesized HB CT complex show it could be used as a pharmaceutical drug in the future. Computational analysis was carried out by DFT studies using the B3LYP function with a basis set of 6-31G(d,p) in the gas phase and PCM analysis. The computational studies further supported the experimental results by confirming the charge and proton transfer complex.

Synthesis, and spectroscopic, nanostructure, surface morphology, and density functional theory studies of new charge-transfer complexes of amifampridine with π-acceptors

The charge transfer (CT) complexes formed between the potassium-channel-blocking drug amifampridine (AMFP) and the π-acceptors; chloranilic acid (CLA) and 2,5-dihydroxy-p-benzoquinone (DHBQ) in both MeOH solutions, and the solid-state were synthesized and fully characterized. The stoichiometry of the complexes formed in MeOH is 1:1, while those of the solid complexes are 2:1 and 1:1 (donor: acceptor) for CLA and DHBQ, respectively. The CT complexes were studied in terms of their formation constants (KCT), molar extinction coefficients (εCT), and spectrophysical and thermodynamic properties, and the results demonstrated the high stability of the complexes in MeOH. The limits of detection and quantification for the complexes by UV–Vis spectrophotometry were also determined. The surface morphologies, particle sizes, and elemental compositions of the complexes were determined, utilizing X-ray powder diffraction, scanning electron microscope, and energy-dispersive X-ray techniques. The molecular structures, and the electronic properties of the complexes were investigated using B3LYP and WB97XD DFT calculations employing 6–31++G(d,p) basis sets, revealing that the magnitude of the CT is 0.357 e in AMFP-CLA and 0.317 e in AMFP-DHBQ, indicating that CLA is a better electron acceptor than DHBQ. The UV–Vis spectral bands observed for AMFP-CLA and AMFP-DHBQ experimentally in MeOH at 488 and 535 nm, respectively, while these bands were calculated at 493.0 at 535.6 nm, respectively, in the same solvent (MeOH). Both bands were found to be due to HOMO→LUMO excitation, where that in the AMFP-CLA complex is an internal electronic transition and that in AMFP-DHBQ complex is a charge transfer based transition from AMFP to DHBQ. Natural bond orbital calculations indicated that the CT processes LP(2)O11→LP*(1)H12 (127.62 kcal mol−1) and LP(1)N20→LP*(1)H12 (317.46 kcal mol−1) in AMFP-DHBQ, and LP(2)O9→LP*(1)H10 (94.84 kcal mol−1) and LP(1)N23→ LP*(1)H10 (363.42 kcal mol−1) in AMFP-CLA provide extra stability to the complexes.

Charge-transfer chemistry of azithromycin, the antibiotic used worldwide to treat the coronavirus disease (COVID-19). Part II: Complexation with several π-acceptors (PA, CLA, CHL)

Finding a vaccine or cure for the coronavirus disease (COVID-19) responsible for the worldwide pandemic and its economic, medical, and psychological burdens is one of the most pressing issues presently facing the global community. One of the current treatment protocols involves the antibiotic azithromycin (AZM) alone or in combination with other compounds. Obtaining additional insight into the charge-transfer (CT) chemistry of this antibiotic could help researchers and clinicians to improve such treatment protocols. Toward this aim, we investigated the CT interactions between AZM and three π-acceptors: picric acid (PA), chloranilic acid (CLA), and chloranil (CHL) in MeOH solvent. AZM formed colored products at a 1:1 stoichiometry with the acceptors through intermolecular hydrogen bonding. An n → π* interaction was also proposed for the AZM-CHL CT product. The synthesized CT products had markedly different morphologies from the free reactants, exhibiting a semi-crystalline structure composed of spherical particles with diameters ranging from 50 to 90 nm.

Proton-transfer and charge-transfer interactions between the antibiotic trimethoprim and several σ− and π−acceptors: A spectroscopic study

The σ−acceptor iodine and π−acceptors chloranil (CHL), chloranilic acid (CLA), and picric acid (PA) were complexed with the antibiotic trimethoprim (TMP) as the donor through transfer-type reactions. The spectroscopic properties and structural morphology of the resultant complexes were investigated in both their soluble and solid states; CHN elemental analysis, 1H NMR, 13C NMR, FT−IR, Raman, UV-visible spectroscopies, TEM, and SEM-EDX were used to determine these properties. This work highlights that TMP reacted with iodine and CHL via a CT interaction and with CLA and PA via a PT interaction to form stable solid complexes that ranged in color from yellow (TMP-PA), to violet (TMP-CLA), brown (TMP-CHL), and black (TMP-iodine). The 1:2 stoichiometry between TMP and iodine and 1:1 stoichiometry with the other acceptors was verified by elemental analysis and the spectrophotometric titration method. TEM revealed that the structural morphologies of the TMP complexes were markedly different ranging from spherical particles with the CHL and CLA acceptors to short rods with iodine acceptor to long tubes with the PA acceptor.

Crystal structure of 4-(dimethylamino)pyridin-1-ium-2,5-dichloro-3,6-dioxocyclohexa-1,4-diene-1,4-bis(olate) 4-dimethylaminopyridine (2:1) water undeca-solvate

The structure of the title compound, 4-(dimethylamino)pyridin-1-ium-2,5-dichloro-3,6-dioxocyclohexa-1,4-diene-1,4-bis(olate) 4-dimethylaminopyridine water undeca-solvate, C57H87Cl5N12O21, obtained from interaction between chloranilic acid (caH2), and dimethyl aminopyridine (DMAP) has been determined by single crystal X-ray diffraction. The title compound, (DMAPH)5(ca)2.5·(DMAP)·11H2O, crystallized in the triclinic crystal system with space group, P (no. 2), a = 13.3824(15) Å, b = 13.4515(17) Å, c = 19.048(2) Å, α = 86.014(4)°, β = 88.821(4)°, γ = 86.367(4)°, V = 3413.3(7) Å3, Z = 2, T = 100(2) K, μ(MoKα) = 0.294 mm-1, Dcalc = 1.414 g/cm3, 59413 reflections measured (3.76° ≤ 2Θ ≤ 56°), 16405 unique (Rint = 0.0517, Rsigma = 0.0589) which were used in all calculations. The final R1 was 0.0460 (I ≥ 2σ(I)) and wR2 was 0.1271 (all data). Using supramolecular chemistry principles, proton donors (chloranilic acid) and acceptor (DMAP) were combined to generate a multicomponent hydrogen-bonded system. Due to the presence of protonated bases (DMAPH+), the dominant interactions are the N+-H···O hydrogen bonds, whereas the negative charges of an acceptor from the chloranilate dianion (ca2-) are delocalized. Additionally, three sets of water clusters in the title compound were identified, namely a cyclic pentamer, a linear, and an acute-shaped trimer water cluster. It was further observed that strong hydrogen bond interactions occurred between the solvated aqua molecule(s) acting as a proton donor and the neutral DMAP acting as a proton acceptor. The crystal packing is further stabilized by O-H···Cl and C-H···Cl weak halogen interactions. The lattice metric strength is further held by observed π-π stacking interactions (centroid-centroid) with inter centroid distances between sets of the DMAPH rings of 3.624(3), 3.642(4), 3.739(3), 3.863(3) and 3.898(3) Å, respectively.

Polymorph and anisotropic Raman spectroscopy of Phz-H2ca cocrystals

The nucleation and growth mechanism and polymorph-property correlations in the molecular cocrystal field are widely sought but currently remain unclear. Herein, a new wire-like morphology of phenazine ( Phz )-chloranilic acid ( H2ca) cocrystal (PHC) is demonstrated for the first time, and the self-assembly of Phz and H2ca is controlled to selectively prepare kinetically stable wires and thermodynamically stable plates. Specifically, low precursor concentration is beneficial for one-dimensional (1D) self-assembly along the [010] crystallographic direction, while only supersaturation can trigger 2D self-assembly along the [100] and [010] directions, respectively. This is understandable in terms of the (020) face showing the largest attachment energy ( E att) and the (002) face possessing the smallest surface energy ( E surf). Moreover, anisotropic Raman spectra related to the mode symmetry and atomic displacements in two types of PHCs are revealed, and the same Raman-active vibrational bands of PHC wire and plate show different polarization responses, which is intrinsically ascribed to their different molecular orientations. Overall, this is the first case that morphologies of cocrystal are precisely tuned with comprehensive investigations of their anisotropic vibrational characteristics.

A novel catalytic adsorptive stripping voltammetric method for the determination of germanium ultratraces in the presence of chloranilic acid and the V(IV)\xb7HEDTA complex

A novel, sensitive catalytic adsorptive stripping voltammetric procedure which can be used to determine trace amounts of germanium is described. The method is based on the interfacial accumulation of the complex formed by Ge(IV) and the product of the reduction of chloranilic acid on the hanging mercury drop electrode or the renewable silver amalgam film electrode, and its subsequent reduction from the adsorbed state followed by the catalytic action of the V(IV)·HEDTA complex. The presence of V(IV)·HEDTA greatly enhances the adsorptive stripping response of Ge. The reduction of the Ge(IV) in the presence of chloranilic acid and V(IV)·HEDTA was investigated in detail and the effects of pH, electrolyte composition, and instrumental parameters were studied. Under optimal conditions, the catalytic peak current of germanium exhibited good linearity for Ge(IV) concentrations in the range of 0.75–60 nM (for 60 s of accumulation at −0.1 V, r2 = 0.995) and a low limit of detection (LOD = 0.085 nM). The procedure was successfully applied to determine Ge in water samples.

Synthesis, spectroscopic, thermal, structural characterization and DFT/TD-DFT computational studies for charge transfer complexes of 2,4-diamino pyrimidine with some benzoquinone acceptors

New charge transfer complexes between the donor 2,4-diamino pyrimidine (DAPY) and the π-acceptors, chloranilic acid (CHA) and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) were synthesized and characterized. Investigations were conducted in liquid state using methanol as solvent at different temperatures and in the solid state. The stoichiometry of the complexes was identified as 1:1 using Job's and the photometric titration methods. The formation constant (KCT) of the complexes was determined, and it was revealed that the KCT of [DAPY-CHA] was slightly higher than that of [DAPY-DDQ]. The spectroscopic physical and thermodynamic parameters were also within the accepted values, confirming the stability of the formed CT complexes. A simple, rapid, and accurate spectrophotometric method for the quantitative analysis of DAPY in its pure form was applied and statistically validated. The solid complexes were prepared and characterized using various analytical tools, including FT-IR, 1H NMR, 13C NMR spectra, UV–Vis spectroscopy, TG analysis and powder X-ray diffraction (XRD). The structures of the [DAPY-CHA] and [DAPY-DDQ] complexes were determined using density functional theory (DFT) at wB97X-D and CAM-B3LYP level of theory employing 6-31++G(d,p) basis sets. The charge transfer process revealed that CHA and DDQ were the electron acceptor molecules, while the DAPY was the electron donor. In the [DAPY-CHA] and [DAPY-DDQ] complexes, the amounts of electrons (average value) transferred from the donor to the acceptor were 0.144 e and 0.063 e, respectively. The electronic properties and the UV–Vis spectra of the studied systems were also discussed, and we found that there was consistency between the experimental and theoretical results.

Highly efficient H-bonding charge-transfer complex for microsupercapacitors under extreme conditions of low temperatures

Owing to sluggish ionic mobility at low temperatures, supercapacitors, as well as other energy-storage devices, always suffer from severe capacity decay and even failure under extreme low-temperature circumstances. Solar-thermal-enabled self-heating promises an attractive approach to overcome this issue. Here, we report a unique H-bonding charge-transfer complex with a high photothermal conversion efficiency of 79.5% at 405 nm based on chloranilic acid and albendazole. Integrated with a microsupercapacitor, the chloranilic acid-albendazole complex (CAC) film prompts an apparent temperature increase of 22.7 °C under 1 sun illumination at −32.6 °C, effectively elevating the working temperature of devices. As a result, the rate capability of the microsupercapacitor has been significantly improved with a 17-fold increase in capacitance at a current density of 60 μA cm −2 , leading to outstanding low-temperature performances. Importantly, the integrated device is capable of working at a low temperature of −30 °C in the open air, which demonstrates the potential of CAC in practical applications for low-temperature ultracapacitive energy-storage devices. An unusual H-bonding charge-transfer complex based on chloranilic acid and albendazole with a high photothermal conversion efficiency of 79.5% is developed. Driven by the efficient solar-thermal effect, planar microsupercapacitors exhibit outstanding electrochemical performances under extreme conditions of low temperature.