Spectroscopic characterization of charge-transfer complexes of morpholine with chloranilic and picric acids in organic media: Crystal structure of bis(morpholinium 2,4,6-trinitrocyclohexanolate)

Electron donor–acceptor interaction of morpholine (morp) with chloranilic acid (cla) and picric acid (pa) as π-acceptors was investigated spectrophotometrically and found to form stable charge-transfer (CT) complexes (n–π*) of [(Hmorp)₂(cla)] and [(Hmorp)(pa)]₂. The donor site involved in CT interaction is morpholine nitrogen. These complexes are easily synthesized from the reaction of morp with cla and pa within MeOH and CHCl₃ solvents, respectively. ¹HNMR, IR, elemental analyses, and UV–vis techniques characterize the two morpholinium charge-transfer complexes. Benesi–Hildebrand and its modification methods were applied to the determination of association constant (K), molar extinction coefficient (?). The X-ray crystal structure was carried out for the interpretation the predict structure of the [(Hmorp)(pa)]₂ complex.     

Synthesis,spectroscopic and thermal structural investigations of the charge-transfer complexes formed in the reaction of 1-methylpiperidine with σ- and π-acceptors

The reactions of the electron donor 1-methylpiperidine (1MP) with the π-acceptors 7,7,8,8-tetracyanoquinodimethane (TCNQ), tetracyanoethylene (TCNE), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil = CHL) and iodine (I₂) were studied spectrophotometrically in chloroform at room temperature. The electronic and infrared spectra of the formed molecular charge-transfer (CT) complexes were recorded. The obtained results showed that the stoichiometries of the reactions are not fixed and depend on the nature of the acceptor. Based on the obtained data, the formed charge-transfer complexes were formulated as [(1MP)(TCNE)₂], [(1MP)(DDQ)]·H₂O, [(1MP)(CHL)] and [(1MP)I]I₃, while in the case of 1MP–TCNQ reaction, a short-lived CT complex is formed followed by rapid N-substitution by TCNQ forming the final reaction products 7,7,8-tricyano-8-piperidinylquinodimethane (TCPQDM). The five solids products were isolated and have been characterized by electronic spectra, infrared spectra, elemental analysis and thermal analysis.     

Solvation and temperature effect on the charge-transfer complex between 2-amino-4-picoline with 2,5-dihydroxy-p-benzoquinone

The charge-transfer (CT) complex between the donor 2-amino-4-picoline (2A4P) and the acceptor 2,5-dihydroxy-p-benzoquinone (DHBQ) was studied spectrophotometrically in different polar and non-polar solvents. The molecular composition of the complex, in all solvents, was determined by Job's method of continuous variation and photometric titrations to be 1:1. Benesi–Hildebrand equation has been applied to estimate the formation constant (K _CT) and molecular extinction coefficient (ε) of the formed complex. The variation in K _CT was rationalised based on Taft–Kamlet and electric permittivity parameters of the used solvents. Thermodynamic parameters ΔH°, ΔG° and ΔS° were estimated, they were all negative so the studied complex is reasonably stable and exothermic in nature. In addition, the thermodynamic properties were observed to be sensitive to the nature of the solvent. Moreover, the solid 1:1 CT complex between 2A4P and DHBQ was isolated and characterised using elemental analysis, FTIR and ¹H NMR measurements.     

The Charge Transfer Complex between 2, 3-diamino-5-bromopyridine and Chloranilic acid: Preparation,Spectroscopic Characterization,DNA binding,and DFT/PCM analysis

A charge transfer hydrogen bonded complex was prepared and experimentally explored in an acetonitrile (ACN) medium between the proton acceptor (electron donor) 2, 3-Diamino-5-bromopyridine and the proton donor (electron acceptor) chloranilic acid. The stoichiometry of the charge transfer complex is 1:1. The Benesi-Hildebrand equation is used to calculate the molar absorptivity (ε_CT), association constant (K_CT) and other spectroscopic physical characteristics. The solid compound was synthesized and studied using several spectroscopic methods. The presence of charge and proton transfers in the resultant complex was supported by ¹H NMR, FT-IR and SEM-EDX investigations. The complex DNA binding ability was investigated using electron absorption spectroscopy, and the CT complex binding mechanism is intercalative. The intrinsic binding constant (K_b) value is 5.2 × 10⁶M?1. The good binding affinity of the CT complex makes it potentially suitable for usage as a pharmaceutical in the future. Molecular docking calculations have been performed between CT complex and DNA (ID = 1BNA) to study the CT-DNA interaction theoretically. To corroborate the experimental findings, calculations based on DFT were carried out in the gas and PCM analysis where the existence of charge and hydrogen transfers. Finally, good agreement between experimental and theoretical computations was observed confirming that the basis set used is appropriate for the system under examination.     

Spectroscopic studies of charge transfer complexes of meso‐tetra‐p‐tolylporphyrin and its zinc complex with some aromatic nitro acceptors in different organic solvents

The charge transfer complex (CTC) formation of 5,10,15,20‐tetra(p‐tolyl)porphyrin (TTP) and zinc 5,10,15,20‐tetra(p‐tolyl)porphyrin with some aromatic nitro acceptors such as 2,4,6‐trinitrophenol (picric acid), 3,5‐dinitrosalicylic acid, 3,5‐dinitrobenzoic acid (DNB) and 2,4‐dinitrophenol (DNP) was studied spectrophotometrically in different organic solvents at different temperatures. The spectrophotometric titration, Job's and straight line methods indicated the formation of 1:1 CTCs. The values of the equilibrium constant (K_CT) and molar extinction coefficient (ε_CT) were calculated for each complex. The ionization potential of the donors and the dissociation energy of the charge transfer excited state for the CTC in different solvents was also determined and was found to be constant. The spectroscopic and thermodynamic properties were observed to be sensitive to the electron affinity of the acceptors and the nature of the solvent. No CT band was observed between Zn‐TTP as donor and DNP or DNB as acceptors in various organic solvents at different temperature. Bimolecular reactions between singlet excited TTP (¹TTP*) and the acceptors were investigated in solvents with various polarities. A new emission band was observed. The fluorescence intensity of the donor band decreased with increasing the concentration of the acceptor accompanied by an increase in the intensity of the new emission. The new emission of the CTCs can be interpreted as a CT excited complex (exciplex). Copyright © 2007 John Wiley & Sons, Ltd.     

Preparation and spectroscopic studies on charge-transfer complexes of 2,2'-bipyridine with picric and chloranilic acids

Charge-transfer (CT) complexes formed on the reaction of 2,2'-bipyridine with some acceptors such as picric acid (HPA) and chloranilic acid (H(2)CA) have been studied in CHCl(3) and MeOH at room temperature. Based on elemental analysis and IR spectra of the solid CT complexes along with the photometric titration curves for the reactions, the data obtained indicate the formation of 1:1 charge-transfer complexes [(bpyH)(PA)] and [(bpyH(2))(CA)], respectively. The infrared and (1)H NMR spectroscopic data indicate a charge-transfer interaction associated with a proton migration from the acceptor to the donor followed by intramolecular hydrogen bonding. The formation constants (K(C)) for the complexes were shown to be dependent on the structure of the electron acceptors used.     

Redox‐Active Metal–Organic Frameworks: Highly Stable Charge‐Separated States through Strut/Guest‐to‐Strut Electron Transfer

Molecular organization of donor and acceptor chromophores in self‐assembled materials is of paramount interest in the field of photovoltaics or mimicry of natural light‐harvesting systems. With this in mind, a redox‐active porous interpenetrated metal–organic framework (MOF), {[Cd(bpdc)(bpNDI)] ? 4.5 H₂O ? DMF}_n ( 1 ) has been constructed from a mixed chromophoric system. The μ‐oxo‐bridged secondary building unit, {Cd₂(μ‐OCO)₂}, guides the parallel alignment of bpNDI (N,N′‐di(4‐pyridyl)‐1,4,5,8‐naphthalenediimide) acceptor linkers, which are tethered with bpdc (bpdcH₂=4,4′‐biphenyldicarboxylic acid) linkers of another entangled net in the framework, resulting in photochromic behaviour through inter‐net electron transfer. Encapsulation of electron‐donating aromatic molecules in the electron‐deficient channels of 1 leads to a perfect donor–acceptor co‐facial organization, resulting in long‐lived charge‐separated states of bpNDI. Furthermore, 1 and guest encapsulated species are characterised through electrochemical studies for understanding of their redox properties.     

Monocyclometalated Gold(III) Monoaryl Complexes—A New Class of Triplet Phosphors with Highly Tunable and Efficient Emission Properties

Highly tunable and rich phosphorescent emission properties based on the stable monocyclometalated gold(III) monoaryl structural motif are reported. Monochloro complexes of the type cis‐[(N^C)Au(C₆H₂(CF₃)₃)(Cl)] N^C=2‐phenylpyridine (ppy)] ( 1 ), [N^C=benzo[h]quinoline (bzq)] ( 2 ), [N^C=2‐(5‐Methyl‐2‐thienyl)pyridine (5m‐thpy)] ( 3 ) were successfully prepared in modest to good yields by reacting an excess of 2, 4, 6‐tris(trifluoromethyl)phenyl lithium (LiFmes) with the corresponding dichloride complexes cis‐[(N^C)AuCl₂]. Subsequent replacement of the chloride ligand in 1 with strong ligand field strength such as cyanide and terminal alkynes resulted in complexes of the type cis‐[(ppy)Au(Fmes)(R)] R=CN ( 4 ), I ( 5 ), C?C?C₆H₅ ( 6 ) and C?C?C₆H₄N(C₆H₅)‐p ( 7 ). Single crystal X‐ray diffraction studies of all the complexes except 7 were performed to further corroborate their chemical identity. Thermogravimetric analysis (TGA) studies of the uncommon cis configured aryl alkyne complex 7 confirmed the high stability of this complex. Detailed photophysical investigations carried out in solution at room temperature, at 77 K (2‐MeTHF) in rigidified media, solid state and 5 wt % PMMA revealed the phosphorescent nature of emission in these complexes. Additionally, their behavior was found to be governed based on both the nature of the cyclometalated ligand and the electronic properties of the ancillary ligands. Highly efficient interligand charge transfer in complex 7 provides access to a wide range of emission colors (solvent‐dependent) from deep blue to red with phosphorescence emission quantum yield of 30 % (441 nm) and 39 % (622 nm) in solution and solid state, respectively, and is the highest reported for any Au^III complexes. DFT and TDDFT calculations carried out further validated the observations and assignments based on the photophysical experimental findings.     

Charge-transfer complexes of meso-substituted porphines

Charge-transfer (CT) complexes of 5,10,15,20-tetramethyl-21H,23H-porphine [H₂(tmp)] and 5,10,15,20-tetraphenyl-21H,23H-porphine [H₂(tpp)] have been prepared with TCNQ-type (TCNQ = 7,7,8,8-tetracyanoquinodimethane) acceptors. The complexes crystallize in a mixed-stacked structure. The electronic state of the complexes has been investigated by combining structural geometry information of the acceptors with vibrational spectroscopy data. The complexes were found to possess neutral ground states. The difference between the donor oxidation potential and the acceptor reduction potential (ΔE) also supports this designation of their electronic states. The CT absorption energy shows a linear correlation with ΔE, which is expected for CT complexes in their neutral ground states. The frontier orbitals of the porphyrin donor that participate in the CT interactions have been examined by calculating the overlap integral between the donor occupied molecular orbitals and acceptor LUMO in the complexes. In the H₂(tmp) and H₂(tpp) complexes, a_2u- and a_1u-type porphyrin HOMO and next-HOMO, respectively, are suggested to both be contributors to the establishment of π–π* CT interactions and formation of the complex.     

Synthesis and spectroscopic studies of charge transfer complex between dihydroxy-p-benzoquinone and 4-dimethylaminopyridine in different solvents

Charge transfer (CT) complex formation between 4-dimethylaminopyridine (4-DMAP) as the electron donor and 2,5-dihydroxy-p-benzoquinone (DHBQ) as the π-electron acceptor has been investigated spectrophotometrically in methanol (MeOH), ethanol (EtOH) and acetonitrile (AN). The stoichiometry of the complex has been identified by Job’s and photometric titration methods to be 1:1. The Benesi–Hildebrand equation has been applied to estimate the formation constant (K_CT) and molecular extinction coefficient (ε). It was found that the value of K_CT is larger in AN than in MeOH and EtOH. The thermodynamic parameters are in agreement with the K_CT values in that the enthalpy of formation (?ΔH) has a larger value both in EtOH and MeOH than in AN, suggesting higher stability of the complex in EtOH. The complex formed between 4-DMAP and DHBQ has been isolated as a solid and characterised using elemental analysis, FTIR and ¹H NMR measurements. Moreover, it has been found that the formed complex involves proton transfer in addition to CT.     

Spectrophotometric and spectroscopic studies of complexation of 8-hydroxyquinoline with π acceptor metadinitrobenzene in different polar solvents

The complexation of electron donor–acceptor complexes of 8-hydroxyquinoline (8HQ) and metadinitrobenzene (MNB) have been studied spectrophotometrically and thermodynamically in different polar solvent at room temperature. A new absorption band due to charge transfer (CT) transition is observed in the visible region. A new theoretical model has been developed which take into account the interaction between electronic subsystem of 8HQ and MNB. The results indicate the extent of charge transfer complexes (CTCs) formation to be more in less polar solvents. Stoichiometry of the complex was found to be 1:1 by straight line method and ¹H NMR between donor and acceptor at the maximum absorption bands. Ionization potential (I_D) and resonance energy (R_N) were determined from the CT transition energy in different solvents. The formation constants of the complexes were determined in different polar solvents from which ΔG° formation of the complexes was estimated and also extinction coefficient of the charge transfer complex (CTC) was calculated. Oscillator strength, transition dipole strengths and maximum wavelength of the CTC (λ_CT) in various solvents and IR spectra of the CTC have also been discussed. It has been observed that all parameters described above changed with change in polarity and concentration of donor.     

Spectrophotometric study of charge transfer complex between 2,6-diaminopyridine and 2,5-dihydroxy-p-benzoquinone

Charge transfer (CT) complex formation between 2,6-diaminopyridine (2,6-DAP) as the electron donor with 2,5-dihydroxy-p-benzoquinone (DHBQ) as the electron acceptor has been studied spectrophotometrically in different polar solvents at room temperature. A new absorption band due to CT complex formation was observed near 490?nm. The stoichiometric ratio of the complex has been identified by Job's, photometric and conductometric titration methods to be 1?:?1. Benesi–Hildebrand equation has been applied to estimate the formation constant (K _CT) and molecular extinction coefficient (ε). They recorded high values confirming high stability of the formed complex. The physical parameters, oscillator strength (f), transition dipole moment (μ), ionisation potential (I _D), resonance energy (R_N ) and standard free energy change (ΔG°) of the formed complex were determined and evaluated in the different solvents. The solid complex between 2,6-DAP and DHBQ has been isolated and characterised using elemental analysis, FT-IR and ¹H-NMR measurements.     

Symmetric and dissymmetric N‐heterocyclic carbene rhodium(I) complexes: a comparative study of their catalytic activities in transfer hydrogenation reaction

Six new [RhBr(NHC)(cod)] (NHC = N‐heterocyclic carbene; cod = 1,5‐cyclooctadiene) type rhodium complexes ( 4–6 ) have been prepared by the reaction of [Rh(μ‐OMe)(cod)]₂ with a series of corresponding imidazoli(in)ium bromides ( 1–3 ) bearing mesityl (Mes) or 2,4,6‐trimethylbenzyl (CH₂Mes) substituents at N¹ and N³ positions. They have been fully characterized by ¹ H, ¹³ C and heteronuclear multiple quantum correlation NMR analyses, elemental analysis and mass spectroscopy. Complexes of type [(NHC)RhBr(CO)₂] (NHC = imidazol‐2‐ylidene) ( 7b–9b ) were also synthesized to compare σ‐donor/π‐acceptor strength of NHC ligands. Transfer hydrogenation (TH) reaction of acetophenone has been comparatively studied by using complexes 4–6 as catalysts. The symmetrically CH₂Mes‐substituted rhodium complex bearing a saturated NHC ligand ( 5a ) showed the highest catalytic activity for TH reaction. Copyright © 2012 John Wiley & Sons, Ltd.     

PAH/PAH(CF3)n Donor/Acceptor Charge-Transfer Complexes in Solution and in Solid-State Co-Crystals

A solution, solid-state, and computational study is reported of polycyclic aromatic hydrocarbon PAH/PAH(CF₃)_n donor/acceptor (D/A) charge-transfer complexes that involve six PAH(CF₃)_n acceptors with known gas-phase electron affinities that range from 2.11(2) to 2.805(15) eV and four PAH donors, including seven CT co-crystal X-ray structures that exhibit hexagonal arrays of mixed π-stacks with 1/1, 1/2, or 2/1 D/A stoichiometries (PAH=anthracene, azulene, coronene, perylene, pyrene, triphenylene; n=5, 6). These are the first D/A CT complexes with PAH(CF₃)_n acceptors to be studied in detail. The nine D/A combinations were chosen to allow several structural and electronic comparisons to be made, providing new insights about controlling D/A interactions and the structures of CT co-crystals. The comparisons include, among others, CT complexes of the same PAH(CF₃)_n acceptor with four PAH donors and CT complexes of the same donor with four PAH(CF₃)_n acceptors. All nine CT complexes exhibit charge-transfer bands in solution with λ_max between 467 and 600 nm. A plot of E(λ_max) versus [IE(donor)−EA(acceptor)] for the nine CT complexes studied is linear with a slope of 0.72±0.03 eV eV⁻¹. This plot is the first of its kind for CT complexes with structurally related donors and acceptors for which precise experimental gas-phase IEs and EAs are known. It demonstrates that conclusions based on the common assumption that the slope of a CT E(λ_max) versus [IE−EA] plot is unity may be incorrect in at least some cases and should be reconsidered.     

吩噻嗪给体受体衍生物激发态的电荷转移

A series of N-bonded donor-acceptor derivatives of phenothiazine containing phenyl （PHPZ）, anisyl （ANPZ）, pyridyl （PYPZ）, naphthyl （NAPZ）, acetylphenyl （APPZ）, and cyanophenyl （CPPZ） as an electron acceptor have been synthesized. Their photophysical properties were investigated in solvents of different polarities by absorption and emission techniques. These studies clearly revealed the existence of an intramolecular charge transfer （ICT） excited state in the latter four compounds. The solvent dependent Stokes shift values were analyzed by the modified Lippert-Mataga equation to obtain the excited state dipole moment values. The large excited state dipole moment suggests that the full （or nearly full） electron transfer take place in the A-D systems. In the system of A-D phenothiazine derivatives, the transition dipole moments Mflu were determined mainly by direct interactions between the solvent-equilibrated fluorescence ^1CT state and ground state because of their lack of significant change with increase of the solvent polarity. The electron structure and molecular conformation of phenothiazine derivatives will be significantly changed with the increase of the electron affinity of the N-10 substituent.     

Regulating Charge-Transfer in Conjugated Microporous Polymers for Photocatalytic Hydrogen Evolution

Bandgap engineering in donor–acceptor conjugated microporous polymers (CMPs) is a potential way to increase the solar-energy harvesting towards photochemical water splitting. Here, the design and synthesis of a series of donor–acceptor CMPs [tetraphenylethylene (TPE) and 9-fluorenone (F) as the donor and the acceptor, respectively], F_0.1CMP , F_0.5CMP , and F_2.0CMP , are reported. These CMPs exhibited tunable bandgaps and photocatalytic hydrogen evolution from water. The donor–acceptor CMPs exhibited also intramolecular charge-transfer (ICT) absorption in the visible region (λ_max=480 nm) and their bandgap was finely tuned from 2.8 to 2.1 eV by increasing the 9-fluorenone content. Interestingly, they also showed emissions in the 540–580 nm range assisted by the energy transfer from the other TPE segments (not involved in charge-transfer interactions), as evidenced from fluorescence lifetime decay analysis. By increasing the 9-fluorenone content the emission color of the polymer was also tuned from green to red. Photocatalytic activities of the donor–acceptor CMPs ( F_0.1CMP , F_0.5CMP , and F_2.0CMP ) are greatly enhanced compared to the 9-fluorenone free polymer ( F_0.0CMP ), which is essentially due to improved visible-light absorption and low bandgap of donor–acceptor CMPs. Among all the polymers F_0.5CMP with an optimum bandgap (2.3 eV) showed the highest H₂ evolution under visible-light irradiation. Moreover, all polymers showed excellent dispersibility in organic solvents and easy coated on the solid substrates.     

The Solvent Effect on H2O2 Generation at Room Temperature Ionic Liquid|Water Interface

H₂O₂ is a versatile chemical and can be generated by the oxygen reduction reaction (ORR) in proton donor solution in molecular solvents or room temperature ionic liquids (IL). We investigated this reaction at interfaces formed by eleven hydrophobic ILs and acidic aqueous solution as a proton source with decamethylferrocene (DMFc) as an electron donor. H₂O₂ is generated in colorimetrically detectable amounts in biphasic systems formed by alkyl imidazolium hexafluorophosphate or tetraalkylammonium bis(trifluoromethylsulfonyl)imide ionic liquids. H₂O₂ fluxes were estimated close to liquid|liquid interface by scanning electrochemical microscopy (SECM). Contrary to the interfaces formed by hydrophobic electrolyte solution in a molecular solvent, H₂O₂ generation is followed by cation expulsion to the aqueous phase. Weak correlation between the H₂O₂ flux and the difference between DMFc/DMFc⁺ redox potential and 2 electron ORR standard potential indicates kinetic control of the reaction.     

C‐O Bond Cleavage of Diethyl Ether and Tetrahydrofurane by [(dpp‐BIAN)AlI(Et2O)] [dpp‐BIAN = 1,2‐bis[(2,6‐di‐iso‐propylphenyl)‐imino]acenaphthene]

At elevated temperatures, the aluminum complex [(dpp‐BIAN)AlI(Et₂O)] ( 1 ) splits the C‐O bonds of diethyl ether and tetrahydrofurane yielding the dimeric alkoxides [(dpp‐BIAN)AlOEt]₂ ( 2 ) and [(dpp‐BIAN)AlO(CH₂)₄I]₂ ( 3 ), respectively. Already at ambient temperatures, a cleavage of the C‐O bond of THF is to observe in the reaction of 1 with CpNa in THF as confirmed by the formation of [(dpp‐BIAN)AlO(CH₂)₄C₅H₅]₂ ( 4a ) and [(dpp‐BIAN)Al{O(CH₂)₄C₅H₅}(THF)] ( 4b ) in a molar ratio of 1:2. The reaction of 1 with t‐BuOK affords the monomeric alkoxide [(dpp‐BIAN)AlO‐t‐Bu(Et₂O)] ( 5 ). Compounds 2 , 3 , and 4a/b were characterized by elemental analyses and IR spectra. Additionally, the structures of 2 and 3 were determined by single crystal X‐ray diffraction.     

Synthesis,Characterization, Redox Properties,and Photodynamics of Donor–Acceptor Nanohybrids Composed of Size‐Controlled Cup‐Shaped Nanocarbons and Porphyrins

Cup‐shaped nanocarbons (CNC) generated by the electron‐transfer reduction of cup‐stacked carbon nanotubes have been functionalized with porphyrins (H₂P) as light‐capturing chromophores. The resulting donor–acceptor nanohybrid has been characterized by thermogravimetric analysis (TGA), Raman and IR spectroscopy, transmission electron microscopy, elemental analysis, and UV/Vis spectroscopy. The weight of the porphyrins attached to the cup‐shaped nanocarbons was determined as 20 % by TGA and elemental analysis. The UV/Vis absorption spectrum of CNC? (H₂P)_n in DMF agrees well with that obtained by the superposition of reference porphyrin (ref‐H₂P) and cup‐shaped nanocarbons. The photoexcitation of the CNC? (H₂P)_n nanohybrid results in formation of the charge‐separated (CS) state to attain the longest CS lifetime (0.64±0.01 ms) ever reported for donor–acceptor nanohybrids, which may arise from efficient electron migration following the charge separation. The formation of a radical ion pair was detected directly by electron spin resonance (ESR) measurements under photoirradiation of CNC? (H₂P)_n with a high‐pressure mercury lamp in frozen DMF at 153 K. The observed ESR signal at g=2.0044 agrees with that of ref‐H₂P^.+ produced by one‐electron oxidation with [Ru(bpy)₃]³⁺ in deaerated CHCl₃, indicating the formation of H₂P^.+. The electron‐acceptor ability of the reference CNC compound (ref‐CNC) was also examined by the electron‐transfer reduction of ref‐CNC by a series of semiquinone radical anions.     

Preparation and Spectroscopic Studies of Charge-Transfer Complexes of Thiamine Hydrochloride with Different Electron Acceptor

Abstract—Electronic interactions associated with charge transfer complexes formation of iodine, chloranilic acid (H₂CA) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) with vitamin B1 have been studied spectrophotometrically. The accumulated data indicated formation of CT-complexes of the general formula [(VB1)(acceptor) _n ], (n = 1 or 2). The 1 : 2 and 1 : 1 donor: acceptor molar ratios were calculated on the basis of elemental analysis and photometric titrations. The solid complexes were prepared and characterized by their conductivity, UV-Vis, IR, and ¹H NMR spectra, and thermogravimetric analyses (TGA, DTG). The characteristic physical constants (K_CT, ε_CT, μ, ΔG, I_p, f, E_CT) of the formed CT-complexes were determined to be strongly dependent on nature of the electron acceptors.