Characterization Of Charge Transfer Complex Research Articles

Formation and characterization of charge transfer complex between alectinib and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone: Application to development of microwell spectrophotometric method

Alectinib (ALC) is a novel highly selective anaplastic lymphoma kinase (ALK) inhibitor that is effective in the treatment of patients with advanced ALK-positive non-small cell lung cancer and lymphomas. This study, describes, for the first time, the formation of a charge transfer complex (CTC) between ALC with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The CTC was characterized using different spectrophotometric and computational techniques. UV–visible spectrophotometry ascertained the formation of the CTC in methanol via the formation of a new broad absorption band with a maximum absorption peak (λmax) at 505 nm. The molar absorptivity (ε) of the complex was 2.72 × 103 L mol−1 cm−1 and its band gap energy was 1.94 eV. The stoichiometric ratio of ALC:DDQ was found to be 1:1. The association constant of the complex was 9.6 × 102 L mol−1, and its standard free energy was −16.98 J mol−1. Computational calculations were conducted using different calculation tools. The computed geometrical parameters, specifically bond lengths, exhibited variations in the CTC compared to the individual reactants (ALC and DDQ). The Mulliken atomic charge analysis indicated increased values for DDQ (the acceptor) and decreased values for ALC (the donor) in the CTC, confirming the formation of a CTC. The reaction was employed as a basis for a novel microwell spectrophotometric method for the quantification of ALC in its bulk form, capsule content, and uniformity testing. This greenness and high throughput of the method was documented. The method represents a valuable tool for routine use in quality control laboratories for analysis of ALC's bulk form and capsules.

Synthesis and spectroscopic characterization of charge transfer complexes of the donor hesperidin and π-acceptors; 2,3-dichloro-5,6-dicyano-1,4- benzoquinone and tetracyanoethylene

The interactions between a biologically active flavonoid, hesperidin (HESP) and two of the most known π- acceptors DDQ and TCNE were investigated leading to two new charge transfer complexes (CTC). UV-Visible spectrophotometry was used to follow the reactions in solution in methanol and ethanol as solvents. Infrared and NMR spectrophotometry was used to characterize the products formed in the solid state reactions.The)1:1(stoichiometry of formed charge transfer complexes (HESP-DDQ and HESP-TCNE) was confirmed by Molar ratio method and Benesi-Hildbrand equation was used to calculate the formation constants KCT and the molar extinction coefficient ɛCT of the formed CTC.CTC formed in the reaction of hesperidin with π-acceptors DDQ and TCNE showed high formation constants KCT. KCT values for both CTC formed in ethanol are higher than those formed in methanol and those found for the HESP-DDQ CTC were higher than those of HESP-TCNE.Our results suggest the formation of stable CT complexes of hesperidin with π-acceptors DDQ and TCNE.

Synthesis, spectroscopic and computational characterization of charge transfer complex of remdesivir with chloranilic acid: Application to development of novel 96-microwell spectrophotometric assay

Remdesivir (REM) is an adenosine triphosphate analog antiviral drug that has received authorization from European Commission and approval from the U.S. Food and Drug Administration for treatment of coronavirus disease 2019 (Covid-19). This study, describes, for the first time, the synthesis of a novel charge transfer complex (CTC) between REM, as electron donor, with chloranilic acid (CLA), as π electron acceptor. The CTC was characterized using different spectroscopic and thermogravimetric techniques. UV–visible spectroscopy ascertained the formation of the CTC in methanol via formation of a new broad absorption band with maximum absorption peak (λmax) at 530 nm. The molar absorptivity (ε) of the complex was 3.33 × 103 L mol−1 cm−1 and its band gap energy was 1.91 eV. The stoichiometric ratio of REM:CLA was found to be 1:1. The association constant of the complex was 1.11 × 109 L mol−1, and its standard free energy was 5.16 × 104 J mole−1. Computational calculation for atomic charges of energy minimized REM was conducted, the site of interaction on REM molecule was assigned and the mechanism of the reaction was postulated. The solid-state CTC was further characterized by FT-IR and 1H NMR spectroscopic techniques. Both FT-IR and 1H NMR confirmed the formation of the CTC and its structure. The reaction was adopted as a basis for developing a novel 96-microwell spectrophotometric method (MW-SPA) for REM. The assay limits of detection and quantitation were 3.57 and 10.83 µg/well, respectively. The assay was validated, and all validation parameters were acceptable. The assay was implemented successfully with great precision and accuracy to the determination of REM in its bulk form and pharmaceutical formulation (injection). This assay is simple, economic, and more importantly, has high throughput property. Therefore, the assay can be valuable for routine in quality control laboratories for analysis of REM's bulk form and pharmaceutical injection.

Convolutive Deconvolutive Voltammetry of Charge Transfer Complexes of 4,4’-Bipyridine With Benzoquinone Derivatives

Convolutive, deconvolutive cyclic voltammetric, digital simulation, chrono- amperometric, scanning electron microscopy (SEM) and transmission electron micro- scopy (TEM) were used for clarifying the characterization of charge transfer complex (CT) of 4,4’-bipyridine with benzoquinone derivatives. These studies were achieved at a gold electrode in TBAPL/CH2Cl2. The kind of the electrode reaction and the kinetic parameters of the CT complex under study were calculated and explained via the above methods, then confirmed via digital simulation. SEM and TEM were performed for characterization of the structural morphology of the presented complex as well as showing the nanostructured of the complex.

Resonance Raman and UV–vis characterization of charge transfer complexes of TCNQ and aromatic amines

Although the molecular charge transfer complexes formed by 7,7,8,8-tetracyanoquinodimethane (TCNQ) and several different donors have been widely investigated in the past, in this paper it is shown for the first time the vibrational spectroscopic characterization of the complexes formed by TCNQ and the simplest series of substituted anilines in solution. The UV–vis spectra indicate the formation of TCNQ complexes stabilized by two aromatic amines in a sandwich π type complex. It was observed that the charge transfer transition energies of the complexes follow a linear correlation with the ionization potential of the amines. The resonance Raman spectra revealed, by the analysis of the ν(CC) and ν(CN) stretching modes of TCNQ, that the complexes keep their neutral character in the ground electronic state, and not as a TCNQ2− dianion species as reported before. The observed enhancement of the TCNQ bands as the amine donor capacity increases, confirmed the charge transfer nature of the electronic transitions. The DFT and TDDFT results were obtained and the theoretical Raman and electronic spectra data supported the experimental findings. The results of the model systems presented herein can contribute to a deep understanding of the photoinduced charge transfer process in complexes of TCNQ, which is a key step in the designing of organic molecular devices.

Structure and characterization of charge transfer complexes of benzo[1,2-b:3,4-b′:5,6-b′′]trithiophene [C3h-BTT

Four charge-transfer complexes of C3h-BTT (2) with the organic acceptors TCNQ, F4TCNQ, chloranil, and fluoranil were prepared and crystallographically characterized.

Spectroscopic Characterization of Charge Transfer Complexes of TCNE with Aromatic Amines - The First Step of Tricyanovinylation Reaction

The first step of electrophilic aromatic substitution reactions generally involves the formation of charge transfer complexes. Tetracyanoethylene (TCNE) in the presence of aromatic amines forms π-type complexes that subsequently lead to tricyanovinylation reaction. Although this kind of reaction was investigated in the past, the spectroscopic characterization of the charge transfer complexes is still lacking, since in many cases the first step of the reaction is too fast to allow their characterization by conventional techniques. In this paper, it is shown the UV-Vis and resonance Raman characterization of the charge transfer complexes formed between TCNE and substituted anilines. The magnitude of the charge transfer could be linearly correlated with the electronic absorpion energies, as well as to the Raman shifts observed for the characteristic ν(C≡N) mode of TCNE. In addition, the results were correlated to ionization potentials of amines, and theoretical calculations by density functional theory/time-dependent density functional theory (DFT/TDDFT) methods were performed to support the experimental data.

Spectroscopic characterization of charge transfer complexes of 2,3-diaminopyridine with chloranilic acid and dihydroxy-p-benzoquinone in polar solvent

Charge transfer (CT) complexes formed between 2,3-aminopyridine (2,3-DAP) as electron donor with the π-electron acceptors chloranilic acid (CHA) and dihydroxy-p-benzoquinone (DHBQ) were investigated spectrophotometrically in ethanol. Minimum–maximum absorbance method has been used for estimating the formation constants of the charge transfer reactions (KCT). Job’s method of continuous variation and photometric titration studies were used to detect the stoichiometric ratios of the formed complexes and they showed that 1:1 complexes were produced. The molar extinction coefficient (ε), oscillator strength (f), dipole moment (μ), charge transfer energy (ECT), ionization potential (IP) and the dissociation energy (W) of the formed complexes were estimated, they reached acceptable values suggesting the stability of the formed CT-complexes. The solid CT-complexes were synthesized and characterized by elemental analyses, 1H NMR and FTIR spectroscopies where the formed complexes included proton and electron transfer.

Synthesis, spectroscopic and structural characterization of charge transfer complexes of 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8,8,8]hexacosane with iodine, TCNE and TCNQ

Abstract The charge transfer interaction of the interesting mixed nitrogen–oxygen donor 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8,8,8]hexacosane (HODABCHC) with σ-electron acceptor iodine and π-acceptors tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) have been investigated spectrophotometrically in chloroform. FT-IR, thermal and elemental analysis measurements are performed for the solid CT-interaction products. The reaction stoichiometries were found to be 1:4, 1:6 and 1:3 donor:acceptor molar ratio for iodine, TCNE and TCNQ reaction systems, respectively. The obtained relatively high reaction stoichiometry values are expected due to the expected high electron donation of the donor (HODABCHC). It contains six oxygen and two nitrogen donor atoms. Accordingly, the formed charge transfer complexes could be formulated as [ ( HODABCHC ) I ] + I 7 - , [(HODABCHC)(TCNE) 6 ] and [(HODABCHC)(TCNQ) 3 ].

Electrochemical and spectrophotometrical investigation of the electron-accepting strength of organic superelectrophiles: X-ray structure of their charge transfer complexes with tetrathiafulvalene

Nitro Benzoxadiazoles (benzofurazans), benzoxadiazoles-N-oxide (benzofuroxans) and benzothiadiazoles are ranked amongst the strongest electrophiles known to date. In the past twenty years, their propensity to act as electron organic acceptors has been less studied. In this paper, we report on the study of their electrochemical behavior and on the structural characterization of charge transfer complexes (CTC) deriving from their interaction with tetrathiafulvalene (TTF) derivatives, both in solution and in the solid state. The first half wave reduction potentials (E(1/2)(I)) associated with a reversible monoelectronic transfer process of a large set of nitro substituted benzoxadiazoles (benzofurazans), benzoxadiazoles-N-oxide (benzofuroxans) and benzothiadiazoles have been determined through a detailed electrochemical approach in acetonitrile with a microelectrode network using the ferrocene as an internal reference potential in this electrochemical study. Determination of the electron affinity (EA(CT)) of this series of substituted electrodeficient heteroaromatics as well as their LUMO energy was performed using the Charge Transfer Spectroscopic (CTS) method in solution and by DFT calculations, respectively. The use of the correlation EA(CT) versus the reversible half wave potential (E(1/2)(I)) appears to be a useful tool to estimate readily the E(1/2)(I) or EA(CT) values when they cannot be experimentally determined. The diffusion coefficient of these electrophiles has, for the first time, been determined in acetonitrile. These air stable electrodeficient heteroaromatics have been explored as potential new organic acceptors in the formation of charge transfer (CT) complexes with TTF derivatives. Crystallographic data of two CT complexes with TTF (especially the C-C and C-S bond lengths of the TTF moieties) indicate that these complexes exhibit weak electron delocalization and that both molecules remain neutral. Their resulting levels of charge transfer were probed using UV-visible, IR spectroscopy and by DFT calculations.

Synthesis and Characterization of Charge-Transfer Complexes of Π-Acceptor TCNQ with Various Phenols

The charge-transfer complexes of formula D(TCNQ)2 are formed between π-acceptor TCNQ (7,7′,8,8′-tetracyanoquinodimethane) and phenolic donors such as p-aminophenol, α-naphthol, 2,4,5-trichlorophenol, and p-cresol. Solution growth and an electrochemical method were used to synthesize the complexes. Their structural analyses were performed using elemental analysis (C, H, N, and halogen), X-ray diffraction (XRD) patterns, scanning electron microscope (SEM) photographs, dc electrical conductivity, and spectral properties (electronic and 1H NMR), which reveals that these quasi-one-dimensional monoclinic crystalline compounds are synthesized in the single phase with space group P2/1/n and are of semiconductor nature at room temperature. The stoichiometric ratio of donor and acceptor in the complex D(TCNQ)2 is found to be in a 1:2 ratio, respectively.

Structural Characterization of Charge Transfer Complexes of the Nickel(IV) Bis(3,1,2-dicarbollyl) Sandwich Compound.

Structural Characterization of Charge Transfer Complexes of the Nickel(IV) Bis(3,1,2-dicarbollyl) Sandwich Compound.