Molecular Charge Transfer Research Articles

Red, orange and yellow crystals of 4,5-bis(4-methoxyphenyl)-2-(3-nitrophenyl)-1H-imidazole

Red non-solvate crystals of the title compound from ethanol, C23H19N3O4, orange solvate crystals from tert-butanol, C23H19N3O4·C4H10O, yellow solvate crystals from dioxane–water, C23H19N3O4·0.5C4H8O2, and intense yellow solvate crystals from benzene–N,N′-dimethylformamide, C23H19N3O4·C6H6, differ from each other in their molecular conformation and hydrogen-bonding scheme. The bathochromic shifts of the crystal color are explained by the molecular planarity and charge-transfer effect among the imidazole mol­ecules.

Theory of electron transfer at electrified interfaces

Some recent achievements in condensed phase molecular charge transfer theory are overviewed, with focus on interfacial electrochemical electron transfer (ET). Elements of available and new formalism are addressed in Sections 2 and 3. New elements considered are, firstly, a new convenient parametric scheme for calculation of the rate constant and electrochemical current. The scheme goes beyond the commonly used quadratic free energy relations and extends straightforwardly to vibrational frequency changes, anharmonic nuclear motion, and nuclear tunnelling in local and vibrationally dispersive environmental modes. Other new elements addressed are adiabatic electrochemical processes, and self-consistent calculations of the electronic–vibrational interaction in long-range ET. Self-consistency leads to non-linear electronic–vibrational features. These enhance charge transfer both by increasing the electronic tunnel factor and by decreasing the activation Gibbs free energy. Elements of charge transfer formalism are followed in Section 4 by a discussion of the theoretical basis of several electrochemical ET systems. Attention is given to electrochemical ET across well-characterized thin films, hot electron electrochemistry, electrochemistry at superconducting electrodes, and ET near a temperature or field induced high order phase transition. Particular attention is given to in situ electrochemical scanning tunnelling microscopy where a dielectric continuum or configurationally fluctuating water molecules in the tunnel gap, molecular adsorbates, and bias voltage and overvoltage spectroscopy for different tunnelling mechanisms, are considered. Section 5 gives a short discussion of some new views on proton conduction in strongly hydrogen bonded systems, and of the electrochemical dihydrogen evolution reaction, with focus on low-temperature features. This part is concluded by some perspectives in areas of molecular scale science (nanotechnology, molecular electronics) which can be expected to hold new cases for pure and applied molecular charge transfer theory.

Spectrophotometric determination of loperamide hydrochloride by acid-dye and charge-transfer complexation methods in the presence of its degradation products

Two simple, sensitive and accurate spectrophotometric methods for the determination of loperamide hydrochloride (lop. HCl) are described. The first method is based on the formation of ion-pair association complex (1:1) with bromothymol blue (BTB), bromophenol blue (BPB) and naphthol blue black B (NBB). The coloured products are extracted into chloroform, and measured spectrophotometrically at 414 (BTB), 415 (BPB) and 627 nm (NBB). Beer’s law was obeyed in the ranges of 5–35, 5–30 and 0.8–11.2 μg ml −1 for BTB, BPB and NBB methods, respectively. The method was found to be specific for the analysis of the drug in presence of its degradation products which can be detected by HPLC procedure. The second method is based on the reaction of the basic loperamide with iodine in chloroform to give molecular charge-transfer complex with intense bands at 295 and 363 nm. Beer’s law was obeyed in the ranges 2.5–17.5 and 2.5–22.5 μg ml −1 for the method at 295 and 363 nm, respectively. Optimization of the different experimental conditions are described for both methods. The proposed methods have been applied successfully for the analysis of the drug in pure form and in its dosage forms. The methods have the advantage of being highly sensitive and simple for the determination of a small dose drug, which is also a weak UV-absorbing compound.

Molecular Recognition and Electron Transfer Across a Hydrogen Bonding Interface

Noncovalent interactions are significant in facilitating molecular recognition and charge transfer in many enzymatic redox processes at protein-protein interfaces. The design of guest (G) and host (H) molecules, which undergo molecular recognition in solution using hydrogen bonding interactions, provides a means of understanding and controlling the nature of these interactions. The role of the hydrogen bonding in the charge transfer processes of these molecular assemblies could simply be a molecular interface for there action, or a more active role in assisting a proton coupled electron-transfer reaction. Weak coupling between the charge-transfer sites and the hydrogen-bonding interface is expected to minimize the latter role. The authors report on a series of transition metal complexes with hydrogen bonding molecular recognition sites capable of forming noncovalent donor acceptor complexes. The authors also determine for the first time the dependence of the rate of intramolecular electron transfer on the reaction driving force across a hydrogen bonding interface.

Structure of Mellitic Trianhydride

Mellitic trianhydride (MTA; benzene-1,2 : 3,4 : 5,6-hexacarboxylic trianhydride), a powerful π-electron acceptor, crystallizes in the cubic space group Pa3 with four molecules in the unit cell and is orientationally twofold disordered. The molecules are packed exclusively via edge-to-face contacts also seen in the isomorphous crystal structures of benzene hexacarbonitrile, benzene hexamine, and all-trans-hexachlorocyclohexane. The orthorhombic crystal structure of benzene is also related to these cubic cases, albeit in distorted fashion. The MTA molecules are non-planar in the crystal, taking the shape of a shallow propeller with approximate D3 symmetry. The non-planarity is ascribed to nucleophilic-electrophilic intermolecular interactions between the five-membered-ring O-atoms and the carbonyl C-atoms. Due to the disorder, the two non-equivalent inner C,C bond lengths of the benzene ring of MTA cannot be resolved. The MTA molecules in the polar crystals of the 1 : 1 molecular charge-transfer complexes with triphenylene and 9,10-dimethylanthracene are ordered and practically planar, and, within experimental error, show equal inner C,C lengths, despite severe adjacent bond-angle distortions. Accordingly, the structure of MTA provides no evidence in support of a so-called `Mills-Nixon effect'.

Dynamic modulation of electron correlation by intramolecular modes in charge-transfer compounds

Electron-phonon and electron-electron interactions are in competition in determining the properties of molecular charge transfer conductors and superconductors. The direct influence of phonons on the electron-electron interaction was not before considered and in the present work the coupling of intramolecular modes to electron-electron interaction (U-vib interaction) is investigated.The effect of this coupling on the frequency of the normal modes of a dimer model is obtained and it is shown that frequency shifts of the Raman active modes are directly related to this coupling. The results are used to obtain the values of the U-vib coupling constants of intramolecular modes of a representative molecule of charge transfer conductors, like tetramethyltetratiafulvalene. Consequences of this coupling on the electron pairing are also suggested.

Antifilarial effect of Artemisia nilagirica extract and its ultra high dilutions against canine dirofilariasis.

An ethanolic extract of the flowering meristems of worm wood, Artemisia nilagirica was allowed to evaporate. The residue, thus obtained, was administered orally on 4 pariah dogs naturally infected with Dirofilaria immitis at 10 mg/kg/day for 15 days and then at 20 mg/kg/day for the next 15 days. Two homoeopathic potencies of the A. nilagirica extract, called Cina 200 and Cina 1000, were obtained commercially and administered orally at 0.1 ml/dog/day for 30 days on two separate batches, each consisting of 4 dogs. Blood was sampled from the dogs before treatment and on day 15, 30, 45 and 75 following the treatment. A. nilagirica extract (Cinaθ) was diluted with 90%ethanol1 : 100 and shaken by 10 manual strokes to prepare the 1st potency, called Cina 1. All subsequent potencies were prepared by mixing 1 part of the preceding potency with 99 parts of 90% ethanol and giving the mixture 10 manual strokes. Cinaθ, Cina 200 and Cina 1000 reduced microfilarial densities in treated dogs by 78.38, 63.06 and 71.40%, respectively on day 30. There were 57.13, 42.44 and 64.20% reduction on day 75. No apparent toxic effect was observed in the treated dogs. Electronic spectra of Cinaθ, Cina 200 and Cina 1000 showed comparable absorbance with the latter two giving a blue shift. Cinaθin CCl4 showed a red shift suggesting molecular complexation and charge transfer (CT) interaction between aqueous ethanol and compounds of A. nilagirica. CT was further evidenced by the NMR spectra of the deuterium nuclei of Cinaθin 90% ethanol. NMR spectra of Cinaθ, Cina 200, Cina 1000 and 90% ethanol indicated a change in the solution structure of Cina 200 and Cina1000. This altered solution structure is thought to be responsible for inducing immune reaction of the hosts against the parasite.

Spectrophotometric Determination of Enrofloxacin Through the Formation of a Binary Complex with Iron III, Ion-Pair and Charge-Transfer Complexation in Pure and Dosage Forms

Three simple and accurate spectrophotometric methods are described for the determination of enrofloxacin, a new fluoroquinolone synthetic orally active broad spectrum antibacterial. The first method is based on the reaction with iron III forming a water soluble yellow complex with maximum absorbance at 434 nm. The method allows the determination of 25–140 μgml−1. The second method involves ion-pair formation with bromocresol purple (BCP) in presence of phthalate buffer (pH 4.8±0.4). The yellow ion-pair is extracted with chloroform and the absorbance is measured at 410 nm. The method allows the determination of 4–18 μgml−1. The third method is based on the reaction of the drug with 8-dichloro-5,6 dicyano-p-benzoquinone (DDQ) in methanol as π-acceptor to give a molecular charge-transfer complex, with maximum absorbance at 460 nm. The method permits the determination of 50–240 μgml−1. Optimization of different experimental conditions were described. Beer's law was obeyed for the three methods and the relative standard deviation was found to be less than 2%. The methods have been applied successfully to the analysis of commercially available enrofloxacin preparations without interference from the ingredient commonly found.

Reaction of thiones with dihalogens; comparison of the solid state structures of 4,5-bis(methylsulfanyl)-1,3-dithiole-2-thione–diiodine, –dibromine and –iodine monobromide

Reaction of 4,5-bis(methylsulfanyl)-1,3-dithiole-2-thione 1 with diiodine or iodine monobromide in CH2Cl2 resulted in the formation of molecular charge-transfer complexes 1·I2 and 1·IBr respectively. Both complexes have been characterised crystallographically and contain a linear S–I–X (X = I or Br) moiety with the sulfur adopting a tetrahedral geometry taking into account the stereochemically active lone pairs. The S–I [2.716(3)] and I–I [2.808(3) Å] bond lengths in 1·I2 are similar to those reported for diiodine complexes of related thione donors. The adduct 1·IBr is the first crystallographically characterised thione–iodine monobromide charge-transfer complex. The S–I distance [2.589(2) Å] is shorter than that in 1·I2, consistent with IBr being a stronger acceptor than I2. The I–Br distance [2.7138(11) Å] is lengthened with respect to that in unco-ordinated IBr, but within bonding distance when compared to the sum of the van der Waals radii for iodine and bromine (3.75 Å). Treatment of 1 with dibromine under identical conditions resulted in the formation of the adduct 1·Br2 and the dithiolylium salt [C5H6S4Br][Br3]·½Br2 2. Treatment of 1 with Br2 in toluene led to the isolation of 1·Br2 only. The crystal structure of 1·Br2 shows the compound to contain a linear Br–S–Br moiety with the sulfur in a T-shaped or Ψ-trigonal bipyramidal environment (taking into account the stereochemically active lone pairs). The structure of 2 reveals a three component system consisting of the [C5H6S4Br]+ cation, the [Br3]– anion and a molecule of Br2 in a 2∶2∶1 ratio. These components are held in the lattice by a series of weak intermolecular interactions which link the tribromide ions and dibromine molecules into zigzag chains.

Article

Second-harmonic generation in the solid state is restricted to materials that crystallize in non-centrosymmetric space groups. Unfortunately, the vast majority of solids crystallize in centrosymmetric space groups and are therefore SHG-inactive. The requirement for solid-state asymmetry is addressed in a new series of organic salts. The acid p-nitrophenylglycine, SHG-inactive due to its centrosymmetric (P1) packing, was coupled to six optically pure amines to form salts and (or) complexes that, by virtue of their chiral counterion, crystallized in non-centrosymmetric space groups. The 1064 nm output from a Nd:YAG laser produced 532 nm second-harmonic generation from each of the six salts, with three of the salts producing second-harmonic intensities at least an order of magnitude greater than that of our standard, urea. X-ray crystallographic analysis was carried out on five of the six salts, and an attempt was made to rationalize the second-harmonic intensity of each of these five salts based on the orientation of its molecular charge-transfer axis in the unit cell and on its chromophore density.Key words: second-harmonic generation, nonlinear optics, chiral organic salts, crystal structures.

Photogeneration of charge in solid films of α-sexithiophene

The modulating electric field effect on the luminescence (EML) and photoconduction (PC) have been studied in order to reveal the charge photogeneration mechanisms in solid films of α-sexithiophene (α-6T). It is found that the EML is due to energy-dependent electric field-mediated branching ratio between the luminescence and dissociation of the emitting excited states. Thus produced free charge carriers are detected as the bulk-generated photocurrent. The results interpreted in terms of the Onsager formalism show the charge separation process to proceed through a very efficient molecular interlayer charge transfer; the charge carrier motion forming the measured current is underlaid by hopping of positive charge carriers (holes) among a hopping site manifold with the energy width determined by torsional disorder. In addition, a dominating hole injection component of PC can be detected under positive bias of the illuminated sandwich system →Al/(α-6T)/Al/glass. It is attributed to annihilation of triplet excitons at the anode. A detailed analysis of this current as a function of excitation light intensity and its penetration in α-6T film allows to characterize dynamic parameters of triplet excitons.

The New Semiconducting Magnetic Charge Transfer Salt (BEDT-TTF)4 • H2O • Fe(C2O4)3 • C6H5NO2: Crystal Structure and Physical Properties

The structure, resistivity and ESR of a new molecular charge transfer salt β-(salt (BEDT-TTF)4 • H2O • Fe(C2O4)3 • C6H5NO2 (BEDT-TTF = bis (ethylenedithio)tetrathiofulvalene) are studied. The structure of the salt consists of successive layers of BEDT-TTF which are packed according to β-type and layers of approximately hexagonal geometry containing alternating H2O and Fe(C2O4)3 3−, with C6H5NO2 lying within the hexagonal cavity. Its main crystallographic parameters are found to be: M = 1999.6(1), a = 10.31(8), b = 20.14(8), c = 35.34(4) Å, β = 92.21(9)° V = 7342.0(5) Å3, space group C2/c; Z = 4. The conductivity of this salt at room temperature is l0 Scm−1 and shows semiconducting behaviour from 20 to 300K. The ESR line width is found to be 38.1 (300 K), which is substantially wider than a typical line width for BEDT-TTF based radical cation salts of the β-type, indicating a two-dimensional character. The comparison of crystal structure and properties of the title compound with other salts of this family (BEDT-TTF)4 • A • Fe(C2O4)3 • C6H5NO2, where A = H2O, K+ or NH4 +, is also carried out.

Electroabsorption spectroscopy of molecular inorganic compounds

Electroabsorption spectroscopy is known to report directly on the changes in dipole moment and molecular polarizability accompanying electronic excited state formation. Because ground-state excited-state dipole moment changes can be equated with effective one-electron transfer distances, experimental electroabsorption spectroscopy holds exceptional promise as a methodology for investigating light-induced charge transfer processes within inorganic systems. A survey of the available studies, including metal-to-ligand charge transfer, ligandto-metal charge transfer and localized and delocalized 'intervalence' charge transfer studies, is presented. Also surveyed are electroabsorption studies aimed at illuminating selected molecular nonlinear optical responses. A general observation from electroabsorption studies has been that experimentally determined oneelectron transfer distances are less than simple geometric descriptions would predict. Mononuclear transition-metal systems have proven to be good models for unravelling the complicating effects of ground-state localizationand many-electron polarization. The capability of electroabsorption spectroscopy to resolve fundamental questions relating to electronic localization and delocalization has been highlightedin a series of studies in bridged dinuclear and tris(diimine) systems. The available electroabsorption data have also been used to reassess a number of molecular charge-transfer related parameters such as the electronic coupling energies and solvent reorganization energies. Very recent studies of putative octupolar complexes and donor-acceptor porphyrinic structures have highlighted the utility of electroabsorption spectroscopy for evaluating second-order nonlinear optical response mechanisms and for providing detailed information about statespecific contributions to overall molecular hyperpolarizabilities.

The new semiconducting magnetic charge transfer salt (BEDT-TTF) 4·H 2O·Fe(C 2O 4) 3·C 6H 5NO 2: crystal structure and physical properties

The structure, resistivity and ESR of a new molecular charge transfer salt β-(BEDT-TTF) 4·H 2O·Fe(C 2O 4) 3·C 6H 5NO 2 (BEDT-TTF = bis(ethylenedithio)tetrathiofulvalene) are studied. The structure of the salt consists of successive layers of BEDT-TTF which are packed according to β-type and layers of approximately hexagonal geometry containing alternating H 2O and Fe(C 2O 4) 3 3−, with C 6H 5NO 2 lying within the hexagonal cavity. Its main crystallographic parameters are found to be: M = 1999.6(1), a = 10.31(8), b = 20.14(8), c = 35.34(4) A ̊ , β = 92.21(9)°; V = 7342.0(5) A ̊ 3 , space group C2 c ; Z = 4 . The conductivity of this salt at room temperature is 10 S cm −1 and it shows semiconducting behaviour from 20 to 300 K. The ESR linewidth is found to be 38.1 (300 K), which is substantially wider than a typical linewidth for BEDT-TTF based radical cation salts of the β-type, indicating a two-dimensional character. The comparison of crystal structure and properties of the title compound with other salts of this family (BEDT-TTF) 4·A·Fe(C 2O 4) 3·C 6H 5NO 2, where A = H 2O, K +, NH 4 +, is also carried out.

Quantitative Structure Retention Relationships of Chloro-N-benzylideneanilines in Normal Phase Liquid Chromatography

Quantitative Structure Retention Relationships (QSRRs) of disubstituted N-benzylideneanilines are studied in normal phase liquid chromatography. Structural descriptors for each solute are calculated. Among the descriptors, four are retained to establish the QSRRs. The first descriptor, the dipolar moment is the most important parameter governing the retention, as it represents more than 90% of the log(k′) variation. The influence of three electronic descriptors, ionization potential and Hammett's constants σX and σY, is emphasized by the comparison of the QSRRs obtained. Considering the solvatochromic parameters of the solvants, it appears that hydrogen bond acidic and basic interactions constitute a secondary effect governing the behavior of the solutes. These specific interactions are explained with molecular conformation and charge transfer.

Reaction of tertiary phosphine selenides, R3PSe (R = Me2N, Et2N or C6H11), with dibromine. The first reported examples of 1∶1 addition

The R3PSeBr2 compounds (R = Me2N, Et2N or C6H11) have been prepared and characterised by 31P-{H} and infrared spectroscopy. The compounds R3PSeBr2 (R = Me2N or C6H11) have also been crystallographically characterised. In contrast to the analogous diiodo compounds R3PSeI2 (which have a molecular Ψ-tetrahedral charge-transfer structure, R3PSeI–I), the R3PSeBr2 compounds adopt Ψ-trigonal bipyramids at the selenium centre (taking account of the stereochemically active lone pairs). The crystal structure of (Me2N)3PSeBr2 exhibits very different d(Se–Br), 2.602(2) and 2.544(2) A. This phenomenon is reasoned to be due to the fact that both staggered and eclipsed Se–Br bonds are observed in the structure. The crystal structure of (C6H11)3PSeBr2 shows two crystallographically independent molecules in the asymmetric unit, d(Se–Br) being identical in one molecule, 2.568(3) and 2.566(3) A, but significantly different in the second molecule, 2.591(3) and 2.556(3) A. A possible explanation for this is the presence of a close non-bonded Br· · ·Br contact in this second (C6H11)3PSeBr2 molecule. The compounds R3PSeBr2 (R = Me2N or C6H11) both exhibit P–Se bonds typical of those expected for single bonds, 2.262(2) and 2.263(2) average, respectively, again in contrast to the analogous diiodo compounds, R3PSeI2, in which significant P–Se double bond character was retained. The 31P-{H} NMR and infrared spectroscopic data for R3PSeBr2 (R = Me2N, Et2N or C6H11) are discussed with respect to those of the parent tertiary phosphine selenide, R3PSe.

Crystal structure of triphenylphosphine sulfide diiodine; the first crystallographically characterised 1∶1 molecular charge-transfer complex of a tertiary phosphine sulfide with diiodine

In CH2Cl2 solution, Ph3PS and diiodine react to form a molecular 1∶1 charge-transfer complex. The complex has been studied in solution using 31P-{H} NMR and UV/VIS spectroscopy. Single-crystal X-ray diffraction and solid-state 31P-{H} NMR studies of Ph3PS·I2 show that the molecular structure is maintained in the solid phase. The structure of Ph3PS·I2 is novel and contradicts previous results which indicated that a 1∶1 (Ph3PS∶I2) complex could not be isolated in the solid state. The I–I distance [2.823(1) A] and the S–I distance [2.753(2) A] in Ph3PS·I2 are comparable with those in charge-transfer complexes of related sulfur donors. However, the I–I distance in Ph3PS·I2 is shorter than that in Ph3PSe·I2 reflecting the weaker donor power of the Ph3PS towards diiodine. The NMR spectroscopic results on Ph3PS·I2 and the analogous Ph3PO and Ph3PSe compounds indicate that the stability of the Ph3PE·I2 complexes increases in the order E = Se > S O.

Syntheses, X-ray structures and second harmonic generation efficiencies of fused ring heterocycles

Second harmonic generation efficiencies of a number of fused ring heterocyclic compounds bearing a nitro group were measured using the Kurtz powder method. Among them, 5-nitroindole has the highest SHG efficiency, 20 times as high as that of urea reference. Several 5-nitroindole derivatives were synthesized in the hope of improving the SHG efficiency. None of the derivatives, however, exhibited higher SHG efficiency than the mother compound. X-ray crystal structures of some of these compounds as well as that of 5-nitroindole itself were determined. In the crystal structure of 5-nitroindole the angle (θ) between the molecular charge transfer axis and the polar axis of the crystal is 52.72 °, which is close to the optimum value 54.74 ° predicted by theory. On the other hand, crystal structures of l,2-dimethyl-5-nitroindole and 1-ethyl-5-nitroindole revealed θ values far from the optimum one, which is consistent with their low SHG efficiencies.

Varieties of charge transfer and bonding between layers in misfit layer compounds (MX)x TX2

The features in interlayer bonding, structure and physical properties of the misfit layer compounds like (MX)xTX2 (with MSn, Pb, Bi, Sb, Rare-earth elements; XS, Se and TTi, Nb, Ta, V, Cr) are discussed compared with the thermodynamic properties and electronic structures of two types of isometric equilibrium molecular charge-transfer complexes (of CTC-I and CTC-II types). Analogous to the CTC-I and CTC-II cases a possibility of two types of a ‘reverse’ charge transfer from X atoms of the TX2 layer toward the MX layer, besides the known charge transfer from the MX to the TX2 layer, is proposed to describe the bonding between layers in the misfit compounds. The X atoms of the TX2 layer that are involved in the interaction with the MX layer similar to that in CTC-I or CTC-II can act as effective scatterers or localization centers of the conduction electrons in the TX2 layer. The localization of the transfered electrons in the MX layer depend on a type of the charge transfer (CTC-I or CTC-II). The stabilization of the CTC-II structure as the temperature is lowered results in carrier localization in both the MX and TX2 layers.

Peculiarity Of Ethylenedioxy Group In Formation Of Conductive Charge-Transfer Complexes Of Bis(Ethylenedioxy) -Dibenzotetrathiafulvalene (BEDC-DBTTF)

The electronic and molecular structures and charge transfer (CT) complex formation of a new electron donor molecule; bis(ethy1enedioxy)-dibenzotetrathiafulvalene (BEDO-DBTTF), were studied from the point of the peculiar ability of ethylenedioxy group in delivering conductive solid complexes. The BEDO-DBTTF molecules afforded 37 solid complexes with 40 kinds of electron acceptor molecules belonging to 5 systems; TCNQ, quinone, fluorene, percyano and nitrophenyl systems. The infrared and ultraviolet-visible-near infrared spectra of the complexes were examined to study the ionicity of their ground states in solid. A plot of CT transition energies and the difference of redox potentials; Δ E(DA), of donor and acceptor molecules indicated that 10 complexes have neutral ground state. No definitely identified back CT bands were observed in the 4 complexes of completely ionic ground state. 23 complexy of partially ionic ground state gave CT transitions below 5×103 cm−1 and are highly conductive. The presence of the ethylenedioxy group in REDO-DBTTF provided wide variety of conductive complexes regardless the size and shape of acceptor molecules, with smaller degree of CT (γ≥0.3), from combination with much weaker acceptor molecules (Δ E(DA)≤ 0.53) than expected for conventional TTF·TCNQ system (γ≥0.5, Δ E(DA)≤0.34) and with donor molecule excess in content. These features are very much resemblance to those of BEDO-TTF which affords a number of metallic complexes and are ascribed to peculiar ability of ethylenedioxy group to assemble self-aggregated donor assemblies. In spite of such similarity, the partially ionic complexes of BEDO-DBTTF are not metallic, maybe due to the lack of the side-by-side intermolecular sulfur**sulfur short contacts that is predicted based on the molecular geometry consideration. Single crystal growth of BEDO-DBTTF complexes was not much successful. 2,5-Dimethyl- and 2,5-dimethoxy-TCNQ complexes, which reside near the boundary of the partial CT and neutral states, afforded complexes with different ionicities, conductivities and optical properties. The crystal structures of neutral complexes of 2,5-dimethyl- and 2,5-dimethoxy-TCNQ as well as that of neutral donor molecules were determined.