Solid Charge-transfer Complexes Research Articles

Liquid− and solid−state study of charge-transfer (CT) interaction between drug triamterene as a donor and tetracyanoethylene (TCNE) as an acceptor

In this work, the liquid–liquid and solid–solid charge-transfer (CT) interactions of drug triamterene (TA) with tetracyanoethylene (TCNE) were reported. The soluble TA-TCNE CT complex was easily generated by mixing acetonitrile solution of TA as the donor and TCNE as the acceptor at room temperature. The solid TA-TCNE CT complex was easily generated by grinding equimolar amounts of TA and TCNE in powder form without any solvent. The results confirmed that the donor interacted with the acceptor via a strong, liquid-state or solid-state reaction generating a CT complex linked by an n → π* transition. The TEM results showed that the CT complex was composed of mixed spherical, oval, and elliptical particles with a mean diameter of ~15 nm. The solid–solid approach proved to be a highly efficient, time- and cost-effective, eco-friendly, and straight-forward means of forming a CT complex with excellent yield (96%).

Solution, and solid investigations on the charge–transfer complexation between seproxetine as a selective serotonin reuptake inhibitor drug with six kinds of π–electron acceptors

The study in this article deals with the donor–acceptor interaction between seproxetine (SRX) donor and π–electron acceptors such as picric acid, dinitrobenzene, p-nitro benzoic acid, 2,6-dichloroquinone-4-chloroimide, 2,6-dibromoquinone-4-chloroimide, and 7,7′,8,8′-tetracyanoquinodi methane which can be referred to by the following chemical abbreviations “PA, DNB, p-NBA, DCQ, DBQ, and TCNQ” respectively, in a liquid medium, and the associated complexes in the solid form were also isolated and characterized. A spectrophotometric titration method was employed to the quantitative analyses of seproxetine HCl in pure form. The stoichiometric analysis based on the molar ratio technique was found to be 1:1 (SRX: π–acceptor) regarding the charge–transfer interactions between the electrons of donor and acceptors. The different physical spectroscopic parameters “formation constant (KCT), molar extinction coefficient (εCT), standard free energy (∆Go), oscillator strength (ƒ), transition dipole moment (μ), resonance energy (RN) and ionization potential (ID)” were calculated according to the spectroscopic data. The charge–transfer complexes which isolated in solid form were well characterized using some of analytical tools “microanalytical, molar conductance, FTIR, 1H-NMR and X-ray powder diffraction”. Thermal stability of solid charge transfer complexes was investigated using TG/DTG thermogravimetric technique. The kinetic thermodynamic values were calculated upon the thermal decomposition diagrams. The surface morphology, particle size and the elementary percentages of the solid SRX charge–transfer complexes were investigated with the help of scanning (SEM) and transmission (TEM) electron microscopies as well as energy-dispersive X-ray spectroscopy (EDX)

Charge Transfer Complex of Neostigmine with 2,3-Dichloro-5,6-Dicyano-1,4-Benzoquinone: Synthesis, Spectroscopic Characterization, Antimicrobial Activity, and Theoretical Study.

BackgroundElectron donor–acceptor interactions are important molecular reactions for the activity of pharmacological compounds. The aim of the study is to develop a charge transfer (CT) complex: synthesis, characterization, antimicrobial activity, and theoretical study.Method and ResultsA solid CT complex of neostigmine (NSG) with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) was synthesized and characterized by infrared spectra, NMR, and UV–visible spectroscopy. The results confirm the formation of a CT complex. The stability of the CT complex between NSG and DDQ in acetonitrile was determined in solution via spectrophotometric measurement, ie, by calculating the formation constant, molar extinction coefficient, and different spectroscopic parameters. The stoichiometry of the formed NSG–DDQ complex was determined using Job's method. The absorption band of the NSG–DDQ complex can be used for the quantification of NSG.ConclusionThe DFT geometry optimization of NSG, DDQ, and the CT complex and the UV comparative study of both theoretical and experimental structures are presented. The experimental results confirm the charge transfer structure. The bacterial study shows that the NSG–DDQ complex has good antibacterial activity against both Gram-positive and Gram-negative bacteria as well as antifungal activity against Candida albicans.

Synthesis, spectroscopic, thermal, structural investigations and biological activity studies of charge-transfer complexes of atorvastatin calcium with dihydroxy-p-benzoquinone, quinalizarin and picric acid

The charge-transfer interactions between n-electron donor, atorvastatin calcium (ATC) and the electron acceptors, 2,5-dihydroxy-1,4-benzoquinone (DHBQ), 1,2,5,8-tetrahydroxy-9,10-anthraquinone (quinalizarin, Quiz), and 2,4,6-trinitrophenol (picric acid, PA) as π-acceptors have been studied spectrophotometrically in methanol by giving highly colored charge transfer complexes. The isolated solid charge-transfer complexes were characterized by elemental, IR, NMR, mass and thermal analysis to elucidate the chemical structure of the obtained solid CT complexes. The stoichiometry of the complexes was found to be 1:2 in [ATC]:[reagent] at DHBQ, quinalizarin, picric acid. This ratio gave the formed charge-transfer complexes in the formulas [(ATC)(DHBQ)2], [(ATC)(Quiz)2], and [(ATC)(PA)2] which was also confirmed by elemental and mass analysis. Their biological activities were also screened against various bacterial organisms. The obtained results are suitable for the estimation of antihyperlipidemic drug, ATC in pharmaceutical dosage forms.

Utilization of tannic acid into spherical structured carbons based on charge-transfer complexation with tetracyanoethylene acceptor: Liquid-liquid and solid-solid interactions

In this study, liquid-liquid and solid-solid interactions between tannic acid (TA) as a donor with tetracyanoethylene (TCNE) acceptor were investigated toward understanding the effect of starting material phase on the end product of a charge transfer (CT) reaction. The liquid-liquid interaction generated a reddish-brown, soluble CT complex, while the solid-solid interaction produced a deep-violet, solid CT complex. The stoichiometry of the interaction was obtained using an elemental analysis of the solid product and spectrophotometric titration and Job's method for the soluble product and these data both indicated a 1:5 (TA:TCNE) molar ratio. The UV–visible and IR measurements support the presence of π-π interactions between the TA donor and TCNE acceptor. The two CT complexes obtained from the two interactions were directly carbonized into particles. These resultant carbon particles were fully characterized using IR, XRD, SEM, and TEM. These analyses revealed that carbon particles with spherical morphology were obtained after the carbonization of the CT complex generated through the solid-solid interaction, while the liquid-liquid interaction led to carbon particles with semi-porous, irregular morphology.

Spectrophotometric determination of fenoprofen calcium drug in pure and pharmaceutical preparations. Spectroscopic characterization of the charge transfer solid complexes

Simple, accurate and robust spectrophotometric method was developed for determination of fenoprofen calcium drug (FPC). The proposed method was based on the charge transfer (CT) reaction of FPC drug (as n-electron donor) with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), 2,4,6-trinitrophenol (picric acid, PA) or 1,2,5,8-tetrahydroxyanthraquinone (Quinalizarin, QZ) (as π-acceptors) to give highly colored charge transfer complexes. Different variables affecting the reaction such as reagent concentration, temperature and time have been carefully optimized to achieve the highest sensitivity. Beer's law was obeyed over the concentration ranges of 2–60, 0.6–90 and 4–30μgmL−1 using DDQ, PA and QZ CT reagents, respectively, with correlation coefficients of 0.9986, 0.9989 and 0.997 and detection limits of 1.78, 0.48 and 2.6μgmL−1 for the CT reagents in the same order. Elucidation of the chemical structure of the solid CT complexes formed via reaction between the drug under study and π-acceptors was done using elemental, thermal analyses, IR, 1H NMR and mass spectrometry. X-ray diffraction was used to estimate the crystallinity of the CT complexes. Their biological activities were screened against different bacterial and fungal organisms. The method was applied successfully with satisfactory results for the determination of FPC drug in fenoprofen capsules. The method was validated with respect to linearity, limit of detection and quantification, inter- and intra-days precision and accuracy. The proposed method gave comparable results with the official method.

Spectroscopic, thermal studies and molecular modelling of charge transfer complexation between 5-amino-2-methoxypyridine with chloranilic acid in different polar solvents

Charge transfer (CT) interaction between 5-amino-2-methoxypyridine (5AMPy), as electron donor (proton acceptor), with 3,6-dichloro-2,5-dihydroxy-p-benzoquinone (chloranilic acid, H2CA), as electron acceptor (proton donor), has been investigated spectrophotometrically in the polar protic solvents ethanol (EtOH) and methanol (MeOH) and the aprotic one acetonitrile (AN). Pink-coloured solution is formed instantaneously upon mixing 5AMPy with H2CA solutions in all solvents, which is the hallmark evidence of CT complex formation. Based on Job’s method of continuous variations, as well as spectrophotometric titrations, the stoichiometry of the complex was found to be 1:1 [(5AMPy) (H2CA)] in all solvents. Benesi–Hildebrand equation has been applied to estimate the formation constant of the produced CT complex (KCT) and its molar absorptivity (ε), they reached high values, confirming the complex high stability. Solid CT complex has been synthesised and analysed by elemental analyses and FTIR, 1H NMR spectroscopies, where 2:1 [(5AMPy)2 (H2CA)] CT complex was obtained.

Validated spectrophotometric methods for the determination of bifonazole in pharmaceuticals by charge transfer complexation

Two simple and selective visible spectrophotometric methods were developed for assay of bifonazole in pure drug and in its pharmaceutical formulation. The developed methods were based on the charge transfer complexation reaction of bifonazole with 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (CAA) for method A and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) for method B, resulting in the formation of colored complex. The colored reaction products were quantitated spectrophotometrically at 517nm and 457nm for bifonazole-CAA and bifonazole-DDQ complexes, respectively. The complexes obeyed Beer’s law in the concentration range of 50.00–400.00 and 5.00–50.00μgmL−1 with molar absorptivities at 0.0956×104 and 0.6953×104Lmol−1cm−1 for method A and method B, respectively. The proposed procedures were successfully applied for the quantitative determination of bifonazole in its pharmaceutical formulation. The solid charge transfer complexes of bifonazole with each of the π-acceptor reagent were also synthesized and characterized by FT-IR spectroscopy.

Synthesis, spectroscopic studies and thermal analysis of charge-transfer complex of 2,2′-bipyridine with 4-hydroxybenzoic acid in different polar solvents

The charge-transfer (CT) complex formed between 2,2′-bipyridine with 4-hydroxybenzoic acid has been studied in methanol and acetone at room temperature. The charge-transfer complex was characterized on the basis of FT-IR, 1H NMR, XRD studies of the solid CT complex, UV–Visible spectroscopy, thermogravimetric analysis (TGA–DTA) and conductivity and the results were discussed. The particle size and the energy of the charge-transfer complex were also determined. The data obtained from the spectroscopic studies indicate the formation of 1:1 charge-transfer complex, associated with a proton migration from the acceptor to the donor followed by intermolecular hydrogen bonding. The conductivity was found to increase with increase in the concentration of the donor.

Spectrophotometric study on the charge-transfer reaction between 4-aminopyridine with 2,5-dihydroxy-p-benzoquinone in methanol and the binary mixture 50% acetonitrile + 50% 1,4-dioxane (v/v)

Charge-transfer (CT) reaction between 4-aminopyridine (4APy) as the electron donor with 2,5-dihydroxy-p-benzoquinone (DHBQ) as the electron acceptor has been investigated spectrophotometrically in methanol (MeOH) and a binary mixture composed of 50% acetonitrile and 50% 1,4-dioxane (v/v) (ANDI). The composition of the complex has been investigated utilising Job's and photometric titration methods to be 1:1. Benesi–Hildebrand equation has been applied to estimate the formation constant of the CT reaction (K CT) and the molecular extinction coefficient (ϵ) where they reached high values confirming high stability of the produced complex. The solid CT complex (4APy–DHBQ) was isolated, and elemental analysis proved its formation in 1:1 ratio. A spectral study on the formed complex has been carried out using infrared and 1H NMR measurements, where it included hydrogen bonding beside CT.

Interaction of atenolol with iodine: a novel structural formula of charge transfer complexes

Interaction of atenolol (ATE), as an electron donor, with iodine (I2), as a typical σ-electron acceptor, has been studied. This interaction occurs in several remarkable steps. The first step is the initial formation of the ATE–I2 outer charge transfer (CT) complex, meanwhile this interaction ends with the formation of the solid CT complex which has the stoichiometric ratio 4:2 (ATE:I2). The synthesized solid CT complex has a novel and amazing structural formula in which hydrogen bonds exist side by side with the CT binding. Formation constants, molar absorption coefficients, and thermodynamic properties, ΔH, ΔS, and ΔG, of this ATE/I2 interaction have been determined and discussed. The different structural forms of the ATE/I2 complexes which occur in each of the different formation steps, involving their stoichiometric ratios, have been determined and confirmed. Several techniques involving UV/Visible, FT-IR, 1H NMR, and Mass spectra have been used in this study. In addition, morphology of the synthesized solid complex has been investigated by the scanning electron microscope. The charge transfer (CT) interaction between atenolol (ATE) and iodine (I2) occurs in several remarkable steps starting with an initial formation of the ATE–I2 outer CT complex and ending by formation of the solid CT complex having the stoichiometric ratio 4:2 (ATE:I2). The synthesized solid CT complex has a novel and amazing structural formula in which hydrogen bonds exist side by side with the CT binding. Several techniques involving UV/Visible, FT-IR, 1H NMR, and Mass spectra have been used in this study. In addition, morphology of the synthesized solid complex has been investigated by the scanning electron microscope (SEM).

Synthesis and Spectrophotometric Determination Ibuprofen Charge Transfer Complexes with P-Chloranil, 7,7,8,8-Tetracyanoquinodimethane, Bromothymol Blue, Methyl Orange and Picric Acid

Three simple, sensitive and inexpensive spectrophotometric methods have been described for the assay of ibuprofen in bulk drugs and pharmaceutical formulations. The developed methods are based on the formation of colored charge transfer complexes of ibuprofen with p-chloranil, 7,7,8,8-tetracyanoquinodimethane, bromothymol blue, methyl orange and picric acid in acetonitrile as solvent. These newly formed complexes were found to absorb at 438, 394, 403, 418, 374 nm respectively. Optimizations of various experimental conditions are described. Beer’s law obeyed in the concentration range6-54, 2-24, 4-28, 3-21 and 4-28 μgmL-1 with correlation coefficient >0.998 in each case and lower limit of detection values were 76, 90, 234, 63 and 189 ng mL-1, respectively. The association constants and standard free energy changes were studied using Benesi-Hildebrand plots. Oscillator’s strength, ionization potential and energy of complexes in the ground state for all the complexes have been calculated. For further confirmation, solid charge transfer complexes were synthesized and characterized by IR and 1H-NMR spectroscopy. The applicability of the method was demonstrated by the determination of studied drugs in commercial tablets with satisfactory results. No interference from excipients was observed in the formulations.

Spectrophotometric Studies of Lamotrigine Charge Transfer Complexes:Synthesis and Characterization

Charge transfer complexes of lamotrigine with 7,7,8,8-tetracyanoquinodimethane, bromothymol blue and picric acid have been investigated by spectrophotometric method. Optimum conditions for the reactions and validation data is reported. Resulting complexes absorb at 394, 404 and 374 nm in the Beer's law range of 0.15-15, 0.25- 10 and 3.0-18 µg mL -1 with correlation coefficient greater than 0.998 in each case and detection limits 45, 47 and 57 µg mL -1 respectively. The data are discussed in terms of molar absorptivity, association constant and Gibb's free energy. Spectral characteristics including oscillator's strength, dipole moment, ionization potential, energy of complexes and resonance energy have been determined. Benesi-Hildebrand plots for each complex have been constructed. The proposed method was applied successfully for the determination of lamotrigine in pharmaceutical formulations. Satisfactory recovery values suggested that the method is reliable for the determination of lamotrigine in pharmaceutical formulations without interference of excipients. Further, solid charge transfer complexes were synthesized and characterized by IR and 1 H NMR spectroscopy.

Charge Transfer Complexes of Gamma Aminobutyric Acid-Analogue, A Neurotransmitter: Synthesis and Spectrophotometric Determination

Here, we report spectrophotometric method for the determination of gabapentin through charge transfer complexes with σ and π acceptors and also with dye stuffs. The method involves ion-pair complex formation of gabapentin with ninhydrin, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, tetracyanoethylene, methyl orange and picric acid. The optimum conditions for the reactions and validation of described procedure have been studied. Resulting complexes absorb at 580, 315, 340, 464 and 342 nm in the Beer’s law range of 2-22, 32-80, 40-360, 12-96 and 15-135 µg mL -1 with correlation coefficient greater than 0.998 in each case respectively. The proposed method was applied successfully for the determination of gabapentin in pharmaceutical formulations. Satisfactory recovery values suggest that the method is reliable for the determination of gabapentin in pharmaceutical formulations without interference of excipients. In addition, the spectral characteristics including oscillator’s strength, dipole moment, ionization potential, energy of complexes, resonance energy and also the thermodynamic parameters i.e. association constant and Gibb’s free energy changes have been determined. Benesi-Hildebrand plots for each complex have been constructed. Further, solid charge transfer complexes of gabapentin were synthesized and characterized by IR spectroscopy.

Charge transfer complex of some nervous and brain drugs – Part 1: Synthesis, spectroscopic, analytical and biological studies on the reaction between haloperidol antipsychotic drugs with π-acceptors

Donor–acceptor interactions between the electron donor haloperidol (HPL) and π-acceptors like 7,7,8,8-tetracyanoquinodimethane (TCNQ) and picric acid (PA) have been studied spectrophotometrically in CH3OH solvent. The donor–acceptor (charge transfer complexes) were discussed in terms of formation constant (KCT), molar extinction coefficient (εCT), standard free energy (ΔGo), oscillator strength (ƒ), transition dipole moment (μ), resonance energy (RN) and ionization potential (ID). The stoichiometry of these complexes was found to be 1:1M ratio and having the formulas [(HPL)(TCNQ)] and [(HPL)(PA)], respectively. The charge transfer interaction was successfully applied to determine of HPL drug using mentioned common π-acceptors also, the results obtained herein are satisfactory for estimation of HPL compound in the pharmaceutical form. The formed solid charge-transfer complexes were also isolated and characterized using elemental analysis, conductivity, (infrared, Raman, and 1HNMR) spectra and X-ray powder diffraction (XRD). The experimental data of elemental analyses are in agreement with calculated data. The infrared spectra of both HPL complexes are confirming the participation of OH of 4-hydroxy-1-piperidyl moiety in the donor–acceptor chelation. The morphological surface of the resulted charge transfer complexes were investigated using scanning electron microscopy (SEM). The thermogravimetric analysis (TG/DTG) and differential scanning calorimetry (DSC) techniques were performed to give knowledge about the thermal stability behavior of the synthesized charge transfer complexes. Thermodynamic parameters were computed from the thermal decomposition data. These complexes were also tested for their antimicrobial activity against six different microorganisms, and the results were compared with the parent drug.

Ultra Sensitive Liquid Chromatographic Method for the Simultaneous Determination of Carbamazepine with Nsaids in API, Pharmaceutical Formulation and Human Serum by Programming the Detector: Application to In Vitro Drug Interaction

Here we describe an ultra-sensitive reverse phase liquid chromatographic method for the simultaneous determination of carbamazepine with NSAIDs in API, pharmaceutical formulation and human serum with UV detection. The separation of these multiple drug components was made by a Bondapak C18 column (10 µm, 25 cm×0.46 cm) using a moderate acidic mixture of mobile phase i.e., methanol:water 80:20 with pH adjusted to 3.0 using 85% o-phosphoric acid. The flow rate of the mobile phase was affixed at 1.0 ml min -1 for the best minimum interval of elusion of all the analytes. The detector response was monitored at isobestic point of 220 nm at ambient temperature. Calibration curves were obtained in the range of 0.4-12 µg mL -1 for carbamazepine, 0.5-16 µg mL -1 for meloxicam and 0.25-8.0 µg mL -1 for ibuprofen and mefenamic acid. Limits of detection were found to be 4.0, 3.0, 1.0, and 13.0 ng mL-1 respectively. The method was compared by programming the detector at individual wavelength of components which showed more sensitivity with linear range 0.10-3.0, 0.15-5.0, 0.10-3.0 and 0.125-4.0 µg mL -1 and detection limits 2.0, 2.0, 1.0, and 3.0 ng mL-1 respectively. ICH guidelines were followed for validation study. The method showed good precision and accuracy within acceptable range and can be successfully applied for the determination of these drugs in pharmaceutical formulations, human serum and clinical laboratories without interference of excipients or endogenous components of serum. In vitro interaction studies have also been carried out at physiological temperature in buffers of various pH (4, 7.4 and 9.0) simulating human stomach environments and % availability has been calculated. Moreover, the solid charge transfer complexes of carbamazepine with interacting NSAIDs were synthesized and characterized by IR spectroscopy and verified by computational molecular modeling.

Synthesis, spectroscopic, thermal and electrical conductivity studies of three charge transfer complexes formed between 1,3-di[(E)-1-(2-hydroxyphenyl)methylideneamino]-2-propanol Schiff base and different acceptors

Charge-transfer complexes (CTC) resulting from interactions of 1,3-di[(E)-1-(2-hydroxyphenyl) methylideneamino]-2-propanol Schiff base with some acceptors such as iodine (I2), bromine (Br2), and picric acid (PiA) have been isolated in the solid state in a chloroform solvent at room temperature. Based on elemental analysis, UV-Vis, infrared, and 1H NMR spectra, and thermogravimetric analysis (TG/DTG) of the solid CTC, [(Schiff)(I2)] (1), [(Schiff)(Br2)] complexes with a ratio of 1:1 and [(Schiff)(PiA)3] complexes with 1:3 have been prepared. In the picric acid complex, infrared and 1H NMR spectroscopic data indicate that the charge-transfer interaction is associated with a hydrogen bonding, whereas the iodine and bromine complexes were interpreted in terms of the formation of dative ion pairs [Schiff+, I 2 ∙− ] and [Schiff+, Br 2 ∙− ], respectively. Kinetic parameters were obtained for each stage of thermal degradation of the CT complexes using Coats–Redfern and Horowitz–Metzger methods. DC electrical properties as a function of temperature of these charge transfer complexes have been studied.

Experimental and spectroscopic studies of charge transfer reaction between sulfasalazine antibiotic drug with different types of acceptors

The charge-transfer (CT) interactions between the electron donor sulfasalazine (SS) and the acceptors 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), p-chloranil (CHL), picric acid (PA) and iodine have been studied spectrophotometrically in CHCl(3) or CH(3) OH solutions. The formed solid CT complexes were also isolated and characterized through infrared, (1) H-NMR, mass spectra as well as elemental and thermal analysis. The CT complexes were discussed in terms of formation constant (K(CT) ), molar extinction coefficient (ε(CT) ), standard free energy (ΔG°), oscillator strength (f), transition dipole moment (µ), resonance energy (R(N) ) and ionization potential (I(D) ). The stoichiometry of these complexes was found to be 1:1 molar ratio and having the formulae [(SS)(DDQ)], [(SS)(CHL)], [(SS)(PA)] and [(SS)(2) I](+) · I(3) (-) , respectively. The charge transfer interaction was successfully applied to the determination of SS drug using mentioned σ and π-acceptors also, the results obtained herein are satisfactory for estimation of SS compound in the pharmaceutical form.

Synthesis, characterization and spectroscopic structural studies of charge-transfer complexes of 1,4,8,11-tetraazacyclotetradecane-5,7-dione with iodine, TCNE and DDQ

Three novel aqueous and solid charge-transfer complexes are synthesized by the reaction of the polynitrogen cyclic n-donor 1,4,8,11-tetraazacyclotetradecane-5,7-dione (TACTDD) with the σ-acceptor iodine, the aliphatic π-acceptor tetracyanoethylene (TCNE) as well as with the aromatic π-acceptor 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) using chloroform as the medium solvent. Photometric titration measurements of the CT-solution complexes confirm the donor to acceptor ratios are 1:2 for TACTDD–I 2 and TACTDD–TCNE reactions while is 1:1 for the reaction TACTDD–DDQ. These reaction stoichiometries are supported by the elemental, thermal and infrared measurements for the formed CT-solids. Accordingly, the reaction products are formulated as [(TACTDD) I]⋅I 3, [(TACTDD)(TCNE) 2] and [(TACTDD)(DDQ)]. The effect of the substituents, electron donating or withdrawing groups in the donor and acceptors compositions on their CT-interactions is discussed.

Spectroscopic characterizations on the N,N′-bis-alkyl derivatives of 1,4,6,8-naphthalenediimide charge-transfer complexes

Charge-transfer (CT) complexes formed from the reactions of two N,N′-bis-alkyl derivatives of 1,4,6,8-naphthalenediimide such as N,N′-bis-[2-hydroxyethyl]-1,4,6,8-naphthalenediimide (BHENDI) and N,N′-bis-[2-N,N-dimethylaminoethyl]-1,4,6,8-naphthalenediimide (BDMAE NDI) with DDQ, CHL, TCNQ, DCQ and DBQ as π-acceptors have been studied spectrophotometrically in chloroform and/or methanol at 25°C. The photometric titration curves for the reactions indicated that the data obtained refer to 1:1 charge-transfer complexes of [(BHENDI)(DDQ)], [(BDMAENDI)(DDQ)], [(BHENDI)(CHL)], [(BDMAENDI)(CHL)], [(BHENDI)(TCNQ)], [(BDMAENDI)(TCNQ)], [(BHENDI)(DCQ)], [(BDMAENDI)(DCQ)], [(BHENDI)(DBQ)] and [(BDMAENDI)(DBQ)] were formed. Benesi–Hildebrand and its modification methods were applied to the determination of association constant (K), molar extinction coefficient (ɛ). The solid CT complexes have been synthesized and characterization by different spectral methods.