Properties Of Charge-transfer Complexes Research Articles

Charge Transfer Complexes of 1,3,6-Trinitro-9,10-phenanthrenequinone with Polycyclic Aromatic Compounds.

Understanding the interactions of organic donor and acceptor molecules in binary associates is crucial for design and control of their functions. Herein, we carried out a theoretical study on the properties of charge transfer complexes of 1,3,6-trinitro-9,10-phenanthrenequinone (PQ) with 23 aromatic π-electron donors. Density functional theory (DFT) was employed to obtain geometries, frontier orbital energy levels and amounts of charge transfer in the ground and first excited states. For the most effective donors, namely, dibenzotetrathiafulvalene, pentacene, tetrathiafulvalene, 5,10-dimethylphenazine, and tetramethyl-p-phenylenediamine, the amount of charge transfer in the ground state was shown to be 0.134−0.240 e−. Further, a novel charge transfer complex of PQ with anthracene was isolated in crystalline form and its molecular and crystal structure elucidated by single-crystal synchrotron X-ray diffraction.

Quantum-Chemical Simulation of the Structure of Charge-Transfer Complexes of 9,10-Phenanthrenequinone Nitro-Derivatives with Phenanthrene. Crystal and Molecular Structure of 1 : 1 Complex of 2,4,7-Trinitro-9,10-phenanthrenequinone with Phenanthrene

Data on the structure and properties of charge transfer complexes of nitro derivatives of 9,10-phenanthrenequinone (acceptor) with phenanthrene (donor) were obtained by quantum chemical calculations. The energies of complex formation, the average distances between donor and acceptor planes, and the total charge transfer amounts were calculated. 1,3,6-Trinitro-9,10-phenanthrenequinone was shown to be the strongest acceptor in the studied series. The crystal and molecular structure of the 1 : 1 complex of 2,4,7-trinitro-9,10-phenanthrenequinone with phenanthrene [C14H5N3O8·C14H10] was determined by X-ray structural analysis.

Organic-Inorganic Charge Transfer Complex with Charge Modulation after Electrical Pre-biasing.

Several breakthroughs in organic optoelectronic devices with new applications and performance improvement have been made recently by exploiting novel properties of charge transfer complexes (CTCs). In this work, a CTC film formed by coevaporating molybdenum(VI) oxide and pentacene (MoO3:pentacene) shows a strong dipole of 2.4 eV with direction controllability via pre-biasing with an external voltage. While CTCs are most widely known for their much red-shifted energy gaps, there is so far no report on their controllable dipoles. By controlling this dipole with an electrical pre-bias in a MoO3:pentacene CTC based device, current changes over 2 orders of magnitude can be achieved. Kelvin probe force microscopy further confirms that surface potential of the MoO3:pentacene film can be modulated by an external electric field. It is shown for the first time that a dipole of controllable direction can be set up inside a CTC layer by pre-biasing. This concept is further tested by incorporating the CTC layer in organic photovoltaic (OPV) devices. It was demonstrated that by pre-biasing the OPV devices in different directions, their open circuit voltages (Voc) can be significantly tuned via the built-in potentials.

Ultrafast excited state dynamics of a stilbene–viologen charge transfer complex and its interaction with alkanediammonium salts

The spectral and thermodynamic properties of charge transfer complexes D∙A and D∙A∙D between (E)-bis(18-crown-6)stilbene (D) and 1,1′-bis(2-ammonioethyl)-4,4′-bipyridinium tetraperchlorate (A) in MeCN were studied. The complex D∙A is highly stable, while the complex D∙A∙D is weakly stable. D∙A does not fluoresce due to fast intramolecular processes of direct and reverse electron transfer. The efficiency of D∙A fluorescence ignition upon adding alkanediammonium salts depends on the length of a carbon chain. The spectral and kinetic characteristics of D∙A and D∙A∙D CT states were obtained by femtosecond transient absorption spectroscopy. It was established that the characteristic time of back electron transfer in the CT state of D∙A∙D (770 fs) is significantly higher than that in the CT state of D∙A (400 fs). In a number of charge transfer complexes, formed by derivatives of 4,4′-bipyridinium and di-(4-pyridinium)-ethylene with ammonioethyl and ammoniopropyl N-substituents, the rate of back electron transfer depends weakly on the acceptor nature, but is determined by the length of the carbon chain of terminal groups.

Electrochemical Properties of Charge Transfer Complexes of 4,4’-bipyridine with Benzoquinone Derivatives

The electrochemical characteristics of charge transfer complex of 4,4’-bipyridine with benzoquinone derivative have been investigated using cyclic voltammetry, convolutive voltammetry and digital simulation methods. Cyclic voltammetry experiments were performed at a platinum working electrode. The electrode reaction pathway, the relevant chemical and electrochemical parameters of theinvestigated complex were determined using cyclic voltammetry, convolution - deconvolution transforms. The extracted electrochemical parameters and the nature of the electrode reaction were verified & confirmed via digital simulation method.

Electrical and dielectric properties of charge transfer complexes: Interactions between norfloxacin and ciprofloxacin with picric acid and 3,5-dinitrobenzoic acid

Semiconductor behavior was observed for all three studied complexes. The dielectric constant for [(Nor)(PA)], [(Cip)(PA)], and [(Nor)(DNB)] seems to be frequency independent at high frequency, that may be attributed to low mobility of charge carriers which can not follow the applied field.

Structure, magnetic and electronic properties of charge transfer complex containing hexacyanoferrate chain and BEDT-TTF column

A novel charge transfer complex containing of hexacyanoferrate (Fe(CN) 6 ) unit, which has been exhibited variety of magnetic topics in prussian blue systems, was synthesized. X-ray analysis of the single crystal obtained by electrolysis of BEDT-TTF (ET) and hexacyanoferrate suggests that this complex contains 1D magnetic hexacyanoferrate chain perpendicular to the conducting ET column. This significant structure implies that significant properties can be expected caused by the interaction between the spin momentum on d-electrons and a conducting π-electrons influenced vertically by the applied magnetic field. From the result of the electrical conducting measurement, it is suggested that is a semiconductor with the activation energy and the conductivity at room temperature to be 0.113eV and 0.46S/cm, respectivity. Detailed X-ray analysis suggests that the occupancies of Fe and C elements in the 1D hexacyanoferrate chain are 0.5, that of N element is 1.0.

Structure, magnetic and electronic properties of charge transfer complex containing hexacyanoferrate chain and bedt-ttf column

A novel charge transfer complex containing of hexacyanoferrate (Fe(CN) 6 ) unit, which has been exhibited variety of magnetic topics in prussian blue systems, was synthesized. X-ray analysis of the single crystal obtained by electrolysis of BEDT-TTF (ET) and hexacyanoferrate suggests that this complex contains 1D magnetic hexacyanoferrate chain perpendicular to the conducting ET column. This significant structure implies that significant properties can be expected caused by the interaction between the spin momentum on d-electrons and a conducting π-electrons influenced vertically by the applied magnetic field. From the result of the electrical conducting measurement, it is suggested that is a semiconductor, with the activation energy and the conductivity at room temperature to be 0.113 eV and 0.46 S/cm, respectivity. Detailed X-ray analysis suggests that the occupancies of Fe and C elements in the 1D hexacyanoferrate chain are 0.5, that of N element is 1.0.

Charge redistribution effect on the properties of charge transfer complexes HnR?XY and HnR?X2 (X, Y = F, Cl, Br, I; R = O, S, N, P)

Systematic studies on structures, energies, charge transfer, dipole moments, and ionic character of a series of weakly bonded charge transfer (CT) complexes (D⋅AB, D = H2O, H2S, NH3, PH3, AB = F2, Cl2, Br2, I2, BrCl, IBr, ClF, ICl, BrF, IF) have been carried out by the hybrid Hartree–Fock density functional theory (HF-DFT) method, where those results are validated by available experimental and theoretical investigations. Employing the Hohenberg–Kohn theorem, the property of a multicomponent system is formulated with contributions from both component properties and the charge redistribution (CR) effect, which describes the electronic coupling between components. For any property of a multicomponent system, provided that the intercomponent coupling is weak enough, the first-order approximation can be applied, which yields a linear correlation of the component contribution to the CR effect. In fact, this kind of linear relationship can be evidenced by all the studied properties including the geometry, energy, charge transfer, dipole moment, and ionic character of all 40 complexes. This approximation quantitatively describes the relative contribution of the components to a given property, which shows the same tendency in a series of complexes. Based on the investigations of the CT effect on the intermolecular bond energy and the total dipole moment, it has been found that the principal bonding character of the title complexes was ascertained to be ionic with the exception of the F2 complexes, which agrees well with the calculated ionic character. The CT effect, though small in a quantitative aspect, is directly connected to various kinds of system properties. The effectiveness and consistency of the present type of calculations in multicomponent systems may allow their wider applications in the study of intermolecular interactions. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 327–338, 2001

Electronic states of novel donor/acceptor type of organic superconductor, (BETS) 2(Cl 2TCNQ)

1H and 77Se NMR measurements have been performed to clarify the electronic properties of charge transfer complexes, (BETS) 2(X 2TCNQ) (X=Cl and Br). In the Cl 2TCNQ complex, a Korringa-like relaxation behavior has been observed in the metallic state at ambient pressure. At 6.5 kbar, where a metal–insulator (M–I) transition is induced, a sign of anitiferromagnetic ordering was observed in the insulating state at 10 K. In the Br 2TCNQ complex, we have also found that 77Se-1/ T 1 forms a peak around the M–I transition temperature and that NMR line is broadened in the insulating state. The nature of the insulating states of both compounds seem to be the same.

Synthesis and physical properties of charge transfer complexes of hmttef

Numbers of charge transfer complexes of HMTTeF were prepared utilizing organic acceptors and anions. Among these complexes, two kinds of HMTTeF molecules ( A, B) exist in both crystals of the BF 4 and HCP complexes. B molecules are sandwiched between the donor columns made of A molecules, with their molecular planes normal to the column. In the crystal of the Et 2TCNQ complex, the HMTTeF and Et 2TCNQ molecule stack in an alternating way. However, this is highly conductive (σ RT=10 −1~10 1Scm −1) with weakly metallic behavior near room temperature.

Preparation and properties of eoet based organic complexes

EOET (ethylenedioxy-ethylenedithio-tetrathiafulvalene) is a known electron donor which is a hybrid molecule between ET and BO. In this report, the physical and structural properties of charge transfer (CT) complexes of EOET with a number of organic electron acceptors are described. It was found that EOET has more similar aspect to BO rather than ET with respect to those properties of CT complexes. EOET molecules exhibited the ability of self-aggregation in the highly conducting salts, as has been seen in the metallic salts of BO.

Synthesis, structure and electrical properties of charge transfer complex [MDA] [Pd(dmit)2

Synthesis, structure and electrical properties of charge transfer complex [MDA] [Pd(dmit)2

Preparation and Properties of CT Complexes Derived from 4-Substituted-amino-TEMPO Radicals

The charge-transfer (CT) complexes of a series of 4-substituted-amino-TEMPO radicals with some acceptors were prepared and their magnetic properties were investigated. The X-ray crystal structural analysis was carried out on the CT complex consisted of 4-azetidyl-TEMPO and TCNQF4; comparison with that of the complex derived from TEMPO and TCNQF4 showed a distinct difference in their molecular/crystal structures, which is considered to reflect the difference in their magnetic properties.

Preparation and Properties of CT Complexes Derived from Verdazyl Radicals

The charge-transfer (CT) complexes of a series of 1,5-diphenyl-3-(p-substituted-phenyl)-verdazyl radicals with TCNQF4 or DDQ were prepared and their magnetic properties were investigated. The X-ray crystal structural analyses on the CT complexes consisted of 3-(4-methoxyphenyl)-, 3-(4-tolyl)-as well as 3-(4-chlorophenyl)-verdazyl radicals and TCNQF4 were carried out and correlated with their magnetic properties in which large decrease of magnetic susceptibility was observed in each complex.

Synthesis and some properties of charge transfer complexes of C 60 with asymmetric donors of tetrathiafulvalene family

New charge transfer complexes: (TMDTDM-TTF) 2C 60(CS 2) 3, TMDTDM-TTF · C 60 · C 6H 6, (EDTTTF) 2C 60CS 2 were synthesized by the reaction of C 60 with asymmetric donors in CS 2 and benzene. XPS- and IR-spectroscopy show a weak charge transfer in these compounds. The influence of the solvents during the formation of the complexes was disscussed. The (TMDTDM-TTF) 2C 60(CS 2) 3 crystal structure reveals that it has a layered structure with alternating sheets of C 60 and donor dimers.

Synthesis, crystal structure and some properties of charge transfer complex of C 60 with asymmetric donor TMDTDM-TTF

The reaction of C 60 with asymmetric donor tetramethylenedithiodimethyl-tetrathiafulvalene (TMDTDM-TTF) in CS 2 yields the (TMDTDM-TTF) 2C 60(CS 2) 3 ( I) molecular complex. The study of the crystal structure of I reveals that it has a layered structure with alternating sheets of C 60 and donor dimers. X-ray photoelectron spectroscopy (XPS) and IR spectroscopy show a weak charge transfer in this compound.

Magnetic properties of charge transfer complexes of manganese porphyrin derivatives and tetracyanoethylene

A series of charge transfer complexes between tetracyanoethylene and manganese(II) tetraphenylporphyrin derivatives with redox potentials (E ° (Mn 3+/2+)) ranging from −0.23 through −0.08 V vs. SCE, were prepared. The magnitude of the charge transfer decreased with the more anodically shifted redox potentials of the porphyrins which have stronger electron withdrawing groups, in the order of phenyl, 4-methoxyphenyl, 2-thienyl, and 4-cyanophenyl substituents at meso positions. The magnitude of the charge transfer reflected in frequency shift of CN vibration of the TCNE. The magnetization curves at very low temperature showed hysteresis. The salt with cathodically-shifted E ° (Mn 3+/2+) has a lower Curie temperature (Tc). In other words, the degree of the charge transfer between TCNE and Mn porphyrin responsible for the high T C value.

Preparation and abnormal magnetic properties of charge transfer complex of C60 with tetrakis - (N-pyrolidinyl) - ethylene

Air sensitive strong electron donor tetrakis - (N - pyrolidinyl) - ethylene (TPYE) was synthesized and its structure was established from its iodine salt by elemental analysis, and spectroscopic method. Charge transfer complex of C 60 with TPYE was prepared. Magnetic studies conducted by SQUID magnetometer show that the magnetic behavior of TPYE-C 60 could be described by supersition of paramagnetic and ferromagnetic component phases. The coercive forces are 105 Oe at 1.8K and 50 Oe at 4.5 K. The residual magnetizations are 6.4 × 10 −4 emu/g at 1.8 K and 4.9 × 10 −5 emu/g at 4.5 K respectively.

Synthesis, structure and physical properties of charge-transfer complexes based on BET–TTF and M(mnt)2(M = Au, Pt)

The crystalline complexes (BET–TTF)[Au(mnt)2] and (BET–TTF)2[Pt(mnt)2] have been obtained by electrocrystallization of BET–TTF [bis(ethylenethio)tetrathiafulvalene] in CH2Cl2 in the presence of M(mnt)2(M = Au, Pt). IR, UV and EPR spectroscopy indicate that both compounds are completely ionized and have diamagnetic anions. (BET–TTF)[Au(mnt)2] crystallizes in the triclinic P space group, a= 7.94(1)A, b= 13.56(2)A, c= 5.80(2)A, V= 586(4)A3 and Z= 1. The structure consists of mixed donor–acceptor stacks along the a axis with close intermolecular S ⋯ S and N ⋯ H contacts which lead to a strongly interlocked packing. The conductivity of (BET–TTF)[Au(mnt)2] parallel to a is 8 × 10–3 S cm–1 at 300 K and presents an activation energy of 0.090 eV, indicative of semiconducting behaviour.