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• Crystal structure of the [Ni(neoc) 2 (NO 3)]+ with three different anions including TCNQ. • New Ni(II) complex with two NO 3 − groups coordinated in two different ways. • Influence of NO 3 − group on the crystal structure of [M(neoc)(NO 3) 2 (H 2 O)]. • Application of several crystallization methods. • Detailed structural analysis with emphasis on inter/intramolecular interactions. The cationic complex [Ni(neoc) 2 (NO 3)]+ with NO 3 − (1), TCNQ− (3), or (TCNQ-TCNQ)2− (4) as counterions, and the neutral complex [Ni(neoc)([NO 3 ]−- κ1O)([NO 3 ]−- κ2O,O´)(H 2 O)] (2) can be obtained from different reactions involving Ni(II), neoc , NO 3 − and TCNQ. The molecular and extended crystal structure of compound 2 , which displays two different coordination modes for NO 3 −, are compared to those of the analogous Mn, Fe and Co compounds, revealing a correlation between the coordination geometry of the nominally monodentate nitrato ligand and the covalent radius of the central metal atom. Despite the differences in molecular geometry, the extended structures of the Ni (2) and Mn compounds are similar to each other but different from those of the Fe and Co complexes, which are similar to each other. Complex 1 was further used in the preparation of a new heterospin compound [Ni(neoc) 2 (NO 3)](TCNQ) (3), having an ionic structure with the same complex cation present in 1 , accompanied by centrosymmetric anion-radicals (ARs) TCNQ•−. Through a different preparation process, complex 4 , with the formula [Ni(neoc) 2 (NO 3)] 2 (TCNQ-TCNQ), containing the same complex cation as in complexes 1 and 3 , but now with the centrosymmetric σ-dimerized dianion (TCNQ-TCNQ)2− has been obtained. The influence of NO 3 −, TCNQ•− and TCNQ-TCNQ2− anions on the crystal structure of the cation [Ni(neoc) 2 (NO 3)]+ in the compounds has been studied. All of the complexes reported here have supramolecular structures governed by hydrogen bonding systems, adding to their stability. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • TCNQ-NiBTC was developed as a novel electrochemical immunosensor. • A highly sensitive immunosensor for the detection of VWF was proposed. • Immunosensor based on TCNQ-NiBTC was used to monitor VWF release from HUVECs. In this work, we developed an immunosensor for determining von Willebrand factor (VWF) by combining a nickel-based metal–organic framework (NiBTC) with 7,7,8,8-tetracyanoquinodimethane (TCNQ), assembling them on a screen-printed electrode (SPE), and immobilizing VWF antibodies on the surface to obtain Ab/TCNQ-NiBTC/SPE. The capture of VWF antigens caused steric hindrance, which mitigated the electrochemical response. The immunoreaction caused a change in the peak current of Ab/TCNQ-NiBTC/SPE, which was proportional to the logarithm of VWF concentration in the range of 1–200 ng/mL, with limits of detection and quantification of 0.887 ng/mL and 2.958 ng/mL, respectively. The proposed Ab/TCNQ-NiBTC/SPE was used to investigate the release of VWF from H 2 O 2 -induced oxidative-injured human umbilical vein endothelial cells. The extent of cell injury and the amount of VWF released increased with an increase in the exposure time to H 2 O 2 ; however, as the cells died due to excessive injury, the amount of VWF released decreased. The proposed TCNQ-NiBTC-based immunosensor can facilitate the convenient and accurate detection of VWF. [ABSTRACT FROM AUTHOR]

Organic cathodes have the advantages of abundant resources, high theoretical specific capacity, and mild synthesis conditions, but suffer from low density, poor electronic conductivity, and high solubility in liquid electrolytes. Herein, we develop a charge-transfer complex by combining 2,5-dihydroxyterephthalic acid (Li 4 C 8 H 2 O 6) and tetracyanoquinodimethane (TCNQ) at room temperature in 1,3-Dioxolane (DOL) solvent, for application in all-solid-state battery to overcome the above problems. Li 4 C 8 H 2 O 6 /TCNQ act as the electron donor/acceptor and combine to form an enhanced electron cloud through π-π interaction to facilitate electron transport. The electron conductivity of charge transfer complex Li 4 C 8 H 2 O 6 -TCNQ is enhanced to 7 × 10−5 S/cm, which is three orders of magnitude higher than the two pristine materials and much higher than most conventional organic cathodes. The Li 4 C 8 H 2 O 6 -TCNQ electrode exhibits a discharge specific capacity of 172 mAh/g at 0.5 C, which is approximately 2.5 times higher than that of Li 4 C 8 H 2 O 6 and higher than its capacity in a liquid cell, and is stable for 100 cycles at 2 C. This result demonstrates that enhancing electron cloud through π-π interaction in charge transfer complexes is an effective way to realize the practical application of organic cathodes in sulfide all-solid-state batteries. [Display omitted] • A charge transfer complex Li 4 C 8 H 2 O 6 -TCNQ was developed for application in all-solid-state batteries. • An enhanced electron cloud is formed by binding through π-π interactions to facilitate electron transport. • The electronic conductivity (7 x 10-5 S/cm) of Li 4 C 8 H 2 O 6 -TCNQ was improved by three orders of magnitude. • Li 4 C 8 H 2 O 6 -TCNQ electrodes showed a 2.5-fold increase in discharge specific capacity to 172 mAh/g at 0.5 C. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) are a kind of functional porous materials with the potential applications in gas adsorption and separation, catalysis, energy storage, sensor, and electrical conductivity. However, the insulating nature of the mostly MOFs limits their application in the electronic field. A new three-dimensional (3D) metal-organic framework composed of Cu2+ centres and polyacid linkers (TATAB3−) was synthesized by solvothermal method, which contains two types of Cu 24 cages. The crystal structure is cubic and each Cu is coordinated by five oxygen atoms which can be confirmed by the single crystal X-ray diffraction, infrared spectra and TGA analysis. The conductivity for this 3D MOF is increased by four orders of magnitude after doping with 7,7,8,8-tetracyanoquinodimethane (TCNQ) and realizes the transformation from an insulator to semiconductor. A new three dimensional metal-organic frameworks composed of Cu2+ centres and polyacid linkers (TATAB3−) was synthesized by solvothermal method, which contains two types of Cu 24 cages. The conductivity of the Cu-MOF was increased by 4 orders of magnitude after doping with TCNQ molecules. This method realized the transformation of Cu-MOF from insulator to semiconductor. Finally, the Conductive mechanism of the doped Cu-MOF has been studied. Unlabelled Image • A new three dimensional metal-organic frameworks composed of Cu2+ centres and polyacid linkers (TATAB3-) was synthesized by solvothermal method, which contains two types of Cu 24 cages. • The structure of the as-synthesized Cu-MOF was not changed after doping with TCNQ molecules. • The conductivity of this 3D MOF was increased by four orders of magnitude after doping with 7,7,8,8-tetracyanoquinodimethane (TCNQ) and realized the transformation from insulator to semiconductor. [ABSTRACT FROM AUTHOR]

Highlights • Cu(TCNQ) 2 @Cu(Fe)OOH shows better activity than other TCNQ-based electrocatalysts. • Develops a method to improve the performance of the TCNQ-based electrocatalysts. • The Cu(TCNQ) 2 @Cu(Fe)OOH possesses long-term stability in alkaline media. Abstract The design and synthesis of highly efficient electrocatalysts for OER are important for energy storing applications. In this communication, Cu(TCNQ) 2 nanorod arrays have been designed and synthesized successfully with a Cu(Fe)OOH nanosheet shell by using a short oxidation process of Cu(TCNQ) 2 and subsequently an ultrafast ion exchange reaction. They are expected to combine a variety of desired merits including a simple and rapid preparation process, a large specific surface area, high conductivity and multiple electrocatalytic active sites. All the worthy characteristics which make Cu(TCNQ) 2 @Cu(Fe)OOH are endowed with an excellent OER catalytic performances with the required overpotential of 261 mV at 25 mA cm−2 only. The present work not only produces a good OER catalyst but also provides us a new idea to design efficient OER electrocatalysts. [ABSTRACT FROM AUTHOR]

Charge-transfer complex (CTC) formation between tioconazole (TCZ) as an n -electron donor and 7, 7, 8, 8-tetracyanoquinodimethane (TCNQ) as a π-acceptor was studied spectrophotometrically with an accompanying kinetic and thermodynamic investigation. Multivariate data analysis via a set of experimental designs was executed for this purpose. A 2 3 - two-level full factorial design (FFD) was used for inspecting the proposed variables while a face-centered central composite design (FCCCD) was used to adjust the levels of variables proved to be significant. Two responses were quantified as a result of this interaction; complex I (Y1, measured at 743 nm) and complex II (Y2, measured at 842 nm). Derringer's function and overlaid contour plots were used to concurrently optimize both responses. Benesi–Hildebrand equation was applied to determine of formation constant (K), and the molar absorptivity (Ɛ) of the formed complex. Different thermodynamic parameters; the standard Gibbs free energy change (∆ G °), the standard enthalpy of formation (∆ H °) and the standard entropy change (∆ S °) were determined for the reaction product. The proposed method was validated regarding the linearity, intra-, and inter-day precision and accuracy, limit of detection, limit of quantification and following the ICH standards. The proposed method was also applied for the determination of TCZ in its pharmaceutical preparations. Having a higher molar absorptivity and higher formation constant, complex II was of choice for all subsequent measurements. Application of Benesi–Hildebrand equation supported the formation of 1: 1 CTC. Thermodynamic study revealed the endothermic characters and the spontaneity of formation of the CTC at high temperature. [ABSTRACT FROM AUTHOR]

TCNQ is one of the most important organic acceptors and lots of its derivatives have been prepared. However the reports on their crystal polymorphs are limited to their complexes, and simple polymorphs of TCNQ derivatives are uncommon. We succeeded in preparation of a novel TCNQ derivative, 2,2'-(2-(prop-2-yn-1-yloxy)cyclohexa-2,5-diene-1,4-diylidene)dimalononitrile, having a propynyloxy group on a substituent. This compound was found to have two crystal polymorphs depending on a solvent for recrystallization. In polymorph I, dimeric hydrogen bonds are formed between acetylenic hydrogens and cyano nitrogens with the molecule in an inversion symmetry. While, in polymorph II, the molecules make intermolecular hydrogen bonds between acetylenic hydrogens and cyano nitrogens with the molecule in 2 1 symmetry, forming a hydrogen bonded molecular helix along the b axis. Besides patterns of the intermolecular hydrogen bonds, difference was recognized in conformation of propynyloxy group. The molecule has an anti conformation in polymorph I and a gauche conformation in polymorph II. DFT calculation indicates that the anti conformer is less stable than the gauche one. But a solvation model suggests the anti conformer is estimated to be more stable in a toluene solution. [ABSTRACT FROM AUTHOR]

We report a composite photocatalyst with a core-shell structure of Ag 3 PO 4 @TCNQ (7,7,8,8-Tetracyanoquinodimethane). TCNQ nano-sheet with a conjugated structure was coated on Ag 3 PO 4 particles to enhanced photocatalysis and the stability of Ag 3 PO 4 . This composite catalyst can improve the contact area between semiconductors, promote the separation efficiency of electron and hole, and improve photocatalytic activity and stability. Ag 3 PO 4 @TCNQ exhibited a high degradation of phenol under visible light. The degradation rate of Ag 3 PO 4 @TCNQ (0.3 wt.%) to degradation phenol achieved almost 100% in 12 min, which was about 23% higher than that of pure Ag 3 PO 4 . In addition, TCNQ wrapped on Ag 3 PO 4 surface, as the core’s protective layer, can effectively improve its stability. After five cycles, the degradation rate still reached 90%, but monomer stability retained only 43%. TCNQ, as a good electron acceptor, can transfer electrons from Ag 3 PO 4 surface well, reduce the reduction of Ag + , and improve the separation efficiency of photogenerated charge, greatly improving the activity and stability of catalyst. TCNQ has a positive position of its energy band relative to Ag 3 PO 4 , and the electrons on the Ag 3 PO 4 conduction band can easily transform to the Lowest Unoccupied Molecular Orbital (LUMO) level of TCNQ to realize the efficient separation of charge, which effectively improve quantum efficiency, thus improving activity and stability of catalyst. [ABSTRACT FROM AUTHOR]

Sliver (Ag) nanodendrites (AgNDs) directly growing on the glassy carbon electrode (GCE) were obtained by an in-situ electrodepositing route under the induction of organic semiconductor 7,7,8,8-tetracyanoquinodimethane (TCNQ). The morphology of the Ag nanostructures can be controlled by the electrodepositing time, applied potentials, and the concentrations of Ag ions. The AgNDs/TCNQ/GCE obtained at the optimized conditions displays the oxygen reduction reaction (ORR) onset potential of 0.98 V, which is the same as that over Pt/C-JM catalyst (0.98 V). It demonstrated that AgNDs possessed the highest electrocatalytic activity for ORR among the various Ag-based electrocatalysts reported in literature in alkaline electrolyte. At the same time, the performance of AgNDs/TCNQ/GCE toward hydrogen peroxide detection was investigated in a range of the concentration from 10 μM to 17 mM. It also showed the higher catalytic activity for hydrogen peroxide reduction reaction with the hydrogen peroxide detection limit reaching 0.47 μM level. The Tafel polarization curve, electrochemically active surface area, and the electrochemical impedance were measured to understand and explore the catalytic behavior of the prepared AgNDs/TCNQ/GCE. The enhanced performance of AgNDs for ORR and hydrogen peroxide detection can be ascribed to the special tree-like morphology with highly-exposed surface and the improved electron transportation capacity of interface between AgNDs and GCE. [ABSTRACT FROM AUTHOR]

Due to their hierarchical structures and high surface areas, several categories of metal organic frameworks (MOFs) have emerged as next-generation materials for a wide variety of applications, including sensors. However, the poor electrical conductivity is a bottleneck to exploit them in the development of electrochemical sensing devices. In this work, we for the first time report the development and application of tetracyanoquinodimethane (TCNQ)- doped thin films of copper-MOF, Cu 3 (BTC) 2 , assembled on gold screen printed electrodes, as an electrochemical sensing platform for highly sensitive detection of a prostate cancer marker. The structural and spectroscopic features of the synthesized material along with the morphological features of the prepared electrodes were characterized with diverse instrumental techniques. Doping the thin films of Cu 3 (BTC) 2 with TCNQ improved the conductance of the base material by nine orders of magnitude (from 10 −12 to 10 −3 S). This conducting platform was modified with antibodies to design an immunosensor for the prostate cancer antigen (PSA). The anti-PSA conjugated TCNQ- Cu 3 (BTC) 2 provided PSA detection in a dynamic linear range of 0.1–100 ng/mL to attain a limit of detection at 0.06 ng/mL. The above sensor was specific to PSA even in the presence of other proteins. The practical utility of the immunosensor was also demonstrated against some spiked serum samples. The herein proposed TCNQ- Cu 3 (BTC) 2 based detection system involves a robust physical immobilization of the antibodies to facilitate the detection of PSA over a broader and clinically significant concentration range. [ABSTRACT FROM AUTHOR]

7,7,8,8-tetracyanoquinodimethane (TCNQ), a strong electron withdrawing olefin, has long been regarded as an ideal compound for the synthesis of semiconducting coordination polymers when coordinated to transition metals. Given that TCNQ is an extremely good electron acceptor, transition metals such as Cu, Ag, Mn, Fe, Co, Ni, Zn and Cd have been surveyed for the synthesis of a variety of metal-TCNQ (MTCNQ) compounds. While each of these metal-organic charge transfer complexes show unique physico-chemical properties, these materials have been primarily investigated for electronics applications. More recently, the applicability of TCNQ class of nanomaterials has emerged in other important areas including catalysis, sensing and biology. In this review, the emerging applicability of MTCNQ complexes for catalysis is discussed. In particular, the fabrication of MTCNQ-based materials where M = Cu or Ag is surveyed, followed by discussion on improving their electron-hole recombination properties through a simple galvanic replacement reaction. The mechanistic aspect during the fabrication of these materials with an emphasis on their applicability in catalysis is outlined. [ABSTRACT FROM AUTHOR]

In the presence of trimethylamine, the reaction of N,N′-benzene bis(salicylidenimine) (H 2 L) with NiCl 2 ·6H 2 O affords a nickel(II) complex, [NiL] ( 1 ), and the reaction of H 2 L with NiCl 2 ·6H 2 O and TCNQ provides a TCNQ compound, [LNi(TCNQ)] ( 2 ). Electrochemical studies show that 1 electrocatalyzes hydrogen evolution, both from acetic acid with a turnover frequency (TOF) of 53.25 moles of hydrogen per mole of catalyst per hour at an overpotential (OP) of 941.6 mV (in DMF), and from an aqueous buffer solution (pH 7.0) with a TOF of 462.33 moles of hydrogen per mole of catalyst per hour at an OP of 836.7 mV. 2 can electrocatalyze hydrogen evolution, both from acetic acid with a TOF of 62.56 moles of hydrogen per mole of catalyst per hour at an OP of 941.6 mV (in DMF), and from an aqueous buffer solution (pH 7.0) with a TOF of 909.58 moles of hydrogen per mole of catalyst per hour at an OP of 836.7 mV. To testify that TCNQ plays a vital role in determining the catalytic activities of the nickel complex, we have systematically studied the electrocatalytic activities of 1 and 2 , to provide a possible catalytic mechanism for hydrogen generation by the nickel complexes. This observation suggests that the presence of TCNQ is a key structural feature for eliciting proton or water reduction catalysis. This can be attributed to negatively charged TCNQ, formed from 2 , that can stabilize the low oxidation state of the nickel ion. [ABSTRACT FROM AUTHOR]

Charge transfer complexes of the doxepin with π – acceptors such as 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), tetracyanoquinodimethane (TCNQ) and p -chloranilic acid ( p- CA) have been studied spectrophotometrically. The stoichiometry of the reactions was studied by Job's method of continuous variations which show that the complexation ratio was 1:1 (acceptor: donor) for DDQ, TCNQ and p- chloranilic acid with doxepin base. The data were discussed in terms of association constant (K), molar absorptivity (ε), free energy change (ΔG), oscillator strength ( f ), transition dipole moment (μ EN ), resonance energy (R N ) and ionization potential (I D ). Three simple, fast and sensitive spectrophotometric methods were proposed for the quantification of doxepin hydrochloride in pure form and drug formulations. The methods (A, B and C) were based on the reaction of doxepin base as n-donor with DDQ, TCNQ and p CA resulting in coloured species which absorbed maximally at 570 nm, 840 nm and 530 nm, respectively. Beer's law was obeyed in the concentration range of 5–45 μg mL − 1 , 40–360 μg mL − 1 , and 40–400 μg mL − 1 for the methods A, B, and C, respectively. A series of variables were studied to optimize the reaction conditions. The developed methods were successfully applied for the determination of doxepin in its formulations with high accuracy and precision and without interference from common excipients. [ABSTRACT FROM AUTHOR]

New charge transfer crystals of π -conjugated, aromatic molecules (phenanthrene and picene) as donors were obtained by physical vapor transport. The melting behavior, optimization of crystal growth and the crystal structure are reported for charge transfer salts with (fluorinated) tetracyanoquinodimethane (TCNQ-F x , x =0, 2, 4), which was used as acceptor material. The crystal structures were determined by single-crystal X-ray diffraction. Growth conditions for different vapor pressures in closed ampules were applied and the effect of these starting conditions for crystal size and quality is reported. The process of charge transfer was investigated by geometrical analysis of the crystal structure and by infrared spectroscopy on single crystals. With these three different acceptor strengths and the two sets of donor materials, it is possible to investigate the distribution of the charge transfer systematically. This helps to understand the charge transfer process in this class of materials with π -conjugated donor molecules. [ABSTRACT FROM AUTHOR]

A new metal–organic polyhedron Cu-MOP with octahedral geometry was constructed by 2,8-dibenzothiophenedicarboxylic acid and dicopper paddlewheel. Cu-MOP exhibited H 2 and CO 2 sorption behavior. Furthermore, Cu-MOP revealed reductive properties towards TCNQ, DDQ, CR and MB due to the electron-donating nature of DBT ligand. [ABSTRACT FROM AUTHOR]

This paper describes the ultrafast decay of the band-edge exciton in PbS quantum dots (QDs) through simultaneous recombination of the excitonic hole and electron with the surface localized ion pair formed upon adsorption of tetracyanoquinodimethane (TCNQ). Each PbS QD ( R = 1.8 nm) spontaneously reduces up to 17 TCNQ molecules upon adsorption of the TCNQ molecule to a sulfur on the QD surface. The photoluminescence of the PbS QDs is quenched in the presence of the reduced TCNQ species through ultrafast (⩽15-ps) non-radiative decay of the exciton; the rate constant for the decay process increases approximately linearly with the number of adsorbed, reduced TCNQ molecules. Near-infrared and mid-infrared transient absorption show that this decay occurs through simultaneous transfer of the excitonic electron and hole, and is assigned to a four-carrier, concerted charge recombination mechanism based on the observations that (i) the PL of the QDs recovers when spontaneously reduced TCNQ 1 − desorbs from the QD surface upon addition of salt, and (ii) the PL of the QDs is preserved when another spontaneous oxidant, ferrocinium, which cannot participate in charge transfer in its reduced state, is substituted for TCNQ. [ABSTRACT FROM AUTHOR]

The crystal structure of [Ni(bpy) 3 ] 2 (TCNQ–TCNQ)(TCNQ) 2 ·6H 2 O (1) was studied by X-ray single-crystal structure analysis at 145 K and 100 K. The crystal structures of 1 at these two temperatures are essentially the same as the crystal structure studied previously at 200 K: the structure is built up of [Ni(bpy) 3 ]2+ complex cations, two centrosymmetric crystallographically independent TCNQ·- anion-radicals, disordered σ- and π-dimerized (TCNQ) 2 units, and water molecules of crystallization. Lowering the temperature from 200 K, via 145 K–100 K has shown that at lower temperatures the proportions of σ- and π-dimerization in the disordered (TCNQ) 2 unit are shifted in favor of σ-dimerization; moreover, variation of the weaker C–C σ-bond formed upon dimerization was observed. In addition, lowering the temperature led to a shortening of the distance between the two crystallographically independent anion-radicals which are stacked along the b -axis with overlapped exo groups. The σ- and π-dimerization in the disordered (TCNQ) 2 unit was studied by quantum chemical calculations which showed smallest energy difference for σ and π-dimer at 200 K with respect to 145 K and 100 K in line with a lowest proportion of the dimerization observed experimentally. Temperature-dependent (1.8–270 K) magnetic study of 1 has shown the contribution of Ni(II) ions (S = 1) and the contribution of four S = 1/2 species carried by TCNQ radicals at higher temperatures, strongly coupled by antiferromagnetic (AFM) exchange interaction at 270 K while at low temperature a negligible contribution of TNCQ radical spins was observed. [Display omitted] • The crystal structure of [Ni(bpy) 3 ] 2 (TCNQ–TCNQ) (TCNQ) 2 ·6H 2 O at 145 K and 100 K was determined. • The presence of disordered σ- and π-dimerized (TCNQ) 2 units in the same compound. • The magnetic response is composed of contributions of Ni(II) ions and various TCNQ units. [ABSTRACT FROM AUTHOR]

Copper and silver surfaces can be used as model systems to study structure formation and interfacial bonding upon adsorption of organic molecules. We have investigated the geometric and electronic structure of ordered monolayers of TCNQ on Cu(0 0 1) and Ag(0 0 1) and of TCNQ+Mn on Ag(0 0 1) surfaces by LEED and photoelectron momentum microscopy. While TCNQ forms an incommensurable superstructure on Cu(0 0 1), two coverage-dependant, commensurable superstructures are established on Ag(0 0 1). Subsequent adsorption of Mn on top of TCNQ/Ag(0 0 1) results in the formation of a long-range ordered mixed metal–organic superstructure, which is also commensurable with the Ag(0 0 1) substrate. The photoelectron spectroscopy (PES) data shows a filling of the TCNQ LUMO by charge transfer from the substrate for all investigated interfaces and the coadsorption of Mn leads to an energy shift of the TCNQ HOMO and LUMO of 230 meV with respect to TCNQ/Ag(0 0 1). The characteristic angle-dependent intensity pattern of the TCNQ LUMO in PES was utilized to investigate the azimuthal orientation of the molecules in the respective unit cells. The angle-resolved PES data was further analyzed to identify lateral band dispersion effects in the adsorbate layers, but no significant dispersion was observed. [ABSTRACT FROM AUTHOR]

The electrical conductivity and morphological characteristics of two conjugated polymers, P3HT and PCPDTBT, p-doped with the strong electron acceptor tetrafluoro-tetracyanoquinodimethane (F4-TCNQ) are studied as a function of dopant concentration. By combining scanning and transmission electron microscopy, SEM and TEM, with electrical characterization, we observe a correlation between the saturation in electrical conductivity and the formation of dopant rich clusters. We demonstrate that SEM is a useful technique to observe imaging contrast for locating doped regions in thin polymer films, while in parallel monitoring the surface morphology. The results are relevant for the understanding of structure property relationships in doped conjugated polymers. [ABSTRACT FROM AUTHOR]

TCNQ@TiO2 visible photocatalyst with core--shell structure was synthesized by adsorption methods. The photocatalytic activity was adjusted by the thickness of the shell. After formation of TCNQ@TiO2 core--shell structure, visible light photoactivity can be obtained. The photocatalyst activity of TCNQ@TiO2 was enhanced gradually with the increasing proportion of TCNQ. When the mass fraction of TCNQ reaches 20%, it exhibits the highest visible activity. The apparent rate constant k of TCNQ@TiO2-20% is 0.2583 h-1, which is almost 67.9 times as high as that of pure TiO2. Under visible irradiation, the photogenerated holes on the HOMO orbit of TCNQ can be injected into the VB of TiO2, resulting in the oxidation of organic pollutant directly. However, the energy of the holes injected into the VB of TiO2 is not high enough to mineralize phenol completely. Under UV irradiation, the photogenerated electrons on the CB of TiO2 can be injected into the LUMO orbit of TCNQ, which is too low that electrons could not combine with O2 easily, interdicting the formation of superoxide radicals and resulting in the decrease of photoactivity. [ABSTRACT FROM AUTHOR]

Highlights: [•] A review of the electro- and photochemical synthesis of a variety of transition metal-TCNQ coordination polymers is presented. [•] Electrochemistry of TCNQ derivatives of coordination polymers based on Cu, Ag, Mn, Fe, Co, Ni, Zn and Cd is discussed. [•] Future outlook of this research area and application of these materials is discussed. [Copyright &y& Elsevier]

Highlights: [•] Seven lanthanide TCNQ complexes were obtained. [•] The reaction solvent has an important effect on the structures of complexes. [•] The magnetic and electrochemical properties of complexes were investigated. [ABSTRACT FROM AUTHOR]

Highlights: [•] Crystal structure of TCNQ salts containing [M(phen)3]2+ cations (M is Mn, Fe or Co). [•] IR and Raman spectra of [M(phen)3](TCNQ)2 anion-radical salts. [•] DFT calculations of the o-phenantroline derived cations. [ABSTRACT FROM AUTHOR]

Abstract: Helium atom scattering and low-energy electron diffraction have been used for studying the adsorption of TCNQ molecules on Cu(100). By optimizing the TCNQ growth procedure through the analysis of He-diffraction spectra, a long range (over 2000Å), ordered molecular overlayer has been attained by TCNQ deposition at 110K followed by thermal annealing at 315K. By contrast, no He-diffraction spectra could be obtained by employing growth methods reported previously. Moreover, TCNQ molecules were found to form a single-domain incommensurate overlayer on Cu(100). The lattice parameters of this structure have been determined from an analysis of the measured high-resolution He-diffraction spectra. [Copyright &y& Elsevier]

Highlights: [•] Three CT-complexes of 4-(aminomethyl) piperidine with the acceptors DDQ, TBCHD and iodine are obtained. [•] The adduct 7,7,8-tricyano-8-aminomethylpiperidinylquinodimethane [TCAMPQDM] is yielded with TCNQ. [•] These CT-complexes are characterized through FTIR, UV–vis, elemental and thermal analysis. [•] The values of K C, ε CT, E CT and ΔG 0 are calculated. [Copyright &y& Elsevier]

Highlights: [•] Three CT-complexes of donor 4BP with the acceptors DDQ, TBCHD and iodine are obtained. [•] An adduct 7,7,8-tricyano-8-benzylpiperidinylquinodimethane [TCBPQDM] is produced with TCNQ. [•] The CT-complexes are characterized through FTIR and UV Vis, elemental and thermal analysis. [•] The values of K CT, ε CT, E CT, ΔG ∘ and Ip are calculated. [Copyright &y& Elsevier]

[Display omitted] • TCNQ molecules in (N-Xy-Qn)(TCNQ) 2 salt are organized in tetramerized stacks. • Charge disproportionation in TCNQ stacks is observed (−0.83 e vs −0.33 e). • Tetramerization and EMV coupling complicates the vibrational spectra. • The room temperature conductivity equals 2.6 mS cm−1. The (N-Xy-Qn)(TCNQ) 2 anion-radical salt characterized by tetramerized stacks of the TCNQ acceptor molecules has been synthesized and characterized using vibrational spectroscopy and electrical resistivity measurements. The bond lengths analysis based on the crystal structure data, indicates that the TCNQ molecules are non-uniformly charged with −0.83 e localized on the inner B molecules and −0.33 e on the outer A molecules within ABBA tetramers. Both infrared and Raman spectra of (N-Xy-Qn)(TCNQ) 2 are dominated by vibrational modes of TCNQ and display splitting related to the tetramerized structure. Many of these features are affected by the strong electron-molecular vibration (EMV) coupling. Other charge-sensitive modes allowed estimation of charge localized on TCNQ, with the results that confirm the charges estimated on basis of the crystal data. Electrical measurements revealed the low-conducting behavior with room temperature conductivity value of 2.6 mS cm−1 and temperature dependence of resistivity that can be explained within the band conduction model. The calculated activation energies range from 0.169 eV to 0.187 eV, depending on the crystallographic direction and thermal history of the sample. [ABSTRACT FROM AUTHOR]

Abstract: Na[Ru(SO3)(TCNQ)(bpy)2] and [Ru(SO3)(bpy)2(TCNE)] complexes were synthesized and characterized by means of electrochemical techniques and electronic, vibrational and electron paramagnetic resonance (EPR) spectroscopies. Vibrational data indicated a metallocyclopropane configuration for TCNE while TCNQ ligand is coordinated through the nitrile fragment. EPR data indicated the reduced state for the metal centers and for the TCNQ ligand (TCNQ−). The values of the potentials assigned to the redox processes associated to the TCNX ligands indicated a decrease in the electron transfer barrier. Data of dielectric measurements hinted that TCNQ containing complex is more polarized than the TCNE containing compound. Impedance spectroscopy measurements indicated a temperature-dependent relaxation process for both the complexes. However, for TCNQ containing complex, the results suggested the transition from long-range to short-range mobility. In addition, two values of activation energy (2.0 and 0.6eV) were calculated for this complex suggesting a phase transition process. [Copyright &y& Elsevier]

Five TCNQ (TCNQ = 7,7,8,8-tetracyano-p-quinodimethane) lanthanide complexes, namely, [Gd2(TCNQ)2(DMF)4(H2O)12][(TCNQ)4]·4H2O (1), [Gd(TCNQ)2(H2O)7][TCNQ]·6H2O·EtOH (2), [Gd2(TCNQ)4(H2O)8(CH3OH)2][(TCNQ)2]·2H2O (3), [Ln(TCNQ)2(H2O)6][TCNQ]·H2O·2MeOH [Ln = Ho (4), Ln = Yb (5)], have been synthesized by salt-elimination reactions. X-ray crystallographic analysis shows that 1–5 are discrete ionic complexes with monomer and dimer structure. Cyclic voltammograms, differential pulse voltammograms and the 1st–10th cycles CV for complexes 1–5 show the reversible one-electron oxidation and reversible one-electron reduction within the electrochemical window of CH3CN. Their electrochemical HOMO–LOMO gap and the reversibility are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Reactions of electron-rich alkynyl- and poly-ynyl-Group 8 complexes with tetracyanoethene (TCNE), tetracyanoquinodimethane (TCNQ) and related compounds usually proceed via an initial radical anion salt of the oxidised complex with formation of an intermediate zwitterionic complex which undergoes a [2 + 2]-cycloaddition reaction to give a polycyano-cyclobutenyl complex. This more or less rapidly experiences a ring-opening (retro-electrocyclic reaction), affording an η 1-polycyano-butadienyl-metal derivative. Further chemistry of these species may involve chelation of the dienyl to give an η 3-polycyano-butadienyl by displacement of a 2-e ligand from the metal centre, or transformations of the CN group(s) to amides by hydrolysis or alcoholysis, cycloaddition of azide (“click” reaction) to give tetrazolato complexes, or addition of terminal alkyne to form a [3]-dendralene. Their potential in heterocyclic synthesis is also demonstrated by the formation of a variety of such systems by reactions of the CN groups, activated by electron-donor metal centres. [Copyright &y& Elsevier]

Abstract: The reactions of the electron donor 1,4,7,10-tetraazacyclododecane (TACDD) with the π-electron 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 (CHL) and 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TBCHD) 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 fixed and depend on the nature of both the donor and the acceptor. Based on the obtained data, the formed charge-transfer complexes were formulated as [(Donor)(Acceptor)2] for the donor (TACDD) and the acceptors TCNQ, TCNE, DDQ, CHL and TBCHD. These CT-complexes were isolated as solids and have been characterized through electronic and infrared spectra as well as elemental and thermal analysis measurements. The formation constants (K CT), charge transfer energy (E CT), molar extinction coefficients (ε CT), free energy change ΔG 0, ionization potential Ip and oscillator strength ƒ of the formed CT-complexes were obtained. [Copyright &y& Elsevier]

Abstract: The reaction of a paddlewheel-type diruthenium(II, II) complex, [Ru2(2,3,5,6-F4-PhCO2)4(MeOH)2] (2,3,5,6-F4-PhCO2 − =2,3,5,6-tetrafluorobenzoate), with acridine (acr) produces an acridine-capped discrete compound, [Ru2(2,3,5,6-F4-PhCO2)4(acr)2]·toluene (1). The Ru–Ru and Ru–Nax (Nax =axial N atom of acridine) bond lengths are 2.3087(5)Å and 2.450Å (average), respectively, and the average Ru–Oeq length (Oeq =carboxylate oxygen atom) is 2.074Å, indicating an oxidation state of [Ru2 II,II]. The reaction of 1 with 7,7,8,8-tetracyano-p-quinodimethane (TCNQ) leads to a π-stacked aggregation with a formulation of [Ru2(2,3,5,6-F4-PhCO2)4(acr)2]·TCNQ·2CH2Cl2 (1-TCNQ). Even in a donor/acceptor aggregated system of 1-TCNQ, the Ru–Ru and Ru–Nax bond lengths are 2.3072(9)Å and 2.443(3)Å, respectively, similar to those of 1, and the average Ru–Oeq length is 2.072Å, which replies an oxidation state of [Ru2 II,II] as well as the case in 1. Indeed, the charge ρ of the TCNQ moiety in 1-TCNQ was evaluated to be almost zero (ρ =−0.063), and the infrared spectra of 1-TCNQ agree with the neutral state of compound. The DFT calculations for 1 have revealed that its HOMO (HOMO[Ru2]) is associated with δ∗ orbital of Ru–Ru bond and lies at −5.088eV, which is very close to the LUMO level for TCNQ (LUMOTCNQ with −5.122eV). The gap between the HOMO[Ru2] and LUMOTCNQ levels could be insufficient to induce CT in 1-TCNQ. [Copyright &y& Elsevier]

Abstract: 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 (K CT), molar extinction coefficient (ε CT), standard free energy (ΔGo ), oscillator strength (ƒ), transition dipole moment (μ), resonance energy (RN ) and ionization potential (I D). 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 ydroxy-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. [Copyright &y& Elsevier]

Abstract: The solid charge-transfer molecular complexes formed in the reaction of the electron donor 1-(2-aminoethyl) piperidine (AEP) with the σ-acceptor iodine and π-acceptors 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), 7,7,8,8-tetracyanoquinodimethane (TCNQ) and 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TBCHD)were studied in chloroform at 25 0C. These were investigated through electronic spectra, infrared spectra, thermal and elemental analysis. The obtained results showed that the formed solid CT-complexes have the formulas , [(AEP)(DDQ)2], [(AEP)(TCNQ)2] and [(AEP)(TBCHD)] in full agreement with the known reaction stoichiometries in solution as well as the elemental measurements. The formation constant K CT (Lmol−1), the molar extinction coefficient ε CT (Lmol−1 cm−1), the free energy change ΔG° (calmol−1), the charge transfer energy E CT, and the ionization potential Ip were calculated for the CT-complexes , [(AEP)(DDQ)2], [(AEP)(TCNQ)2] and [(AEP)(TBCHD)]. [Copyright &y& Elsevier]

Abstract: A new, simple and effective amperometric acetylcholinesterase biosensor was developed using screen-printed carbon electrodes modified with carbon nanotubes (MWCNTs)–7,7,8,8-tetracyanoquinodimethane (TCNQ). The design of the biosensor was based on the supramolecular arrangement resulted from the interaction of MWCNTs and TCNQ. This arrangement was confirmed by spectroscopic and electrochemical techniques. Two different supramolecular arrangements were proposed based on different MWCNTs:TCNQ ratios. The synergistic effect of MWCNTs and TCNQ was, for the first time, exploited for detection of thiocholine at low potential with high sensitivity. The biosensor developed by immobilization of acetylcholinesterase (AChE) in sol–gel allowed the detection of two reference AChE inhibitors, paraoxon-methyl and chlorpyrifos with detection limits of 30pM (7ppt) and 0.4nM (0.1ppb), respectively. Efficient enzyme reactivation was obtained by using obidoxime. [Copyright &y& Elsevier]

Abstract: The CT-interaction of electron acceptors such as chloranilic acid (H2CA), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and and 7,7′,8,8′-tetracyano-p-quinodimethane (TCNQ) with the antiviral drug famciclovir (FCV) have been investigated spectrophotometrically in the defined solvent. The data indicate the formation of CT-complexes with the general formula [(FCV)(acceptor)]. The 1:1 stoichiometry of the (FCV)-acceptors were based on elemental analysis, IR spectra and thermogravimetric analysis of the solid CT-complexes along with the photometric titration measurements for the reactions. The formation constants (K CT) for the CT-complexes are shown to be strongly dependent on the type and structure of the electron acceptor. Factors affecting the CT-processes such as redox potentials and steric hinderance of reactants are discussed. [Copyright &y& Elsevier]

Abstract: The degree of charge transfer in thin films of organic charge transfer (CT)-complexes, which are deposited via thermal evaporation, is examined via infrared-spectroscopy. We demonstrate a linear relationship between the shift in the excitation energy of the CN-stretching mode of CT-complexes with the acceptor 7,7,8,8-tetracyanoquinodimethane (TCNQ) and the charge transfer. The measured correlation corresponds very well with DFT calculations. For Na-TCNQ we observe a splitting in the peak of the CN-stretching mode, which can be explained by the coupling of two modes and was confirmed by the calculations. In CT-complexes with partial charge transfer the appearance of an electronic excitation is demonstrated. [Copyright &y& Elsevier]

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)(TCNE)6] and [(HODABCHC)(TCNQ)3]. [Copyright &y& Elsevier]

Abstract: The effect of charge transfer (CT) in complexes of the donors tetra- and hexamethoxyprene (TMP and HMP) with the classical acceptor tetracyanoquinodimethane (TCNQ) was studied using hard X-ray photoemission (HAXPES). Microcrystals of the complex were grown via vapour diffusion from donor–acceptor mixtures. The bulk sensitivity of HAXPES at a photon energy of 6keV completely eliminates the problem of surface contamination for such delicate organic materials grown from solution. The donor molecules were produced using a novel synthesis route functionalizing polycyclic aromatic hydrocarbons at their periphery. For comparison, spectra were also taken from thin-film samples of the same compounds produced via co-deposition in UHV. Upon complex formation, the oxygen 1s core-level spectra (being a fingerprint of the methoxy-group of the donors) change from the single-line spectrum of pure HMP (TMP) to a spectrum with two distinct lines shifted by 1.4 (0.9)eV and 2.6 (2.3)eV with respect to the position of the oxygen 1s line of the pure donors. The nitrogen 1s spectra (being a fingerprint of the cyano-group in the acceptor) show two peaks as well with a corresponding shift of 0.9eV and 2.0eV in comparison with the leading line of pure TCNQ in opposite direction to the oxygen 1s spectra. These values are substantially larger than shifts in near edge X-ray absorption fine structure (NEXAFS) and ultraviolet photoelectron spectroscopy (UPS) spectra of the same complexes. The changes in the spectra are discussed in terms of the CT in the complexes. Residues of pure donor and acceptor materials in the microcrystal fractions of the complexes are evident from the presence of non-shifted lines. Peak-area analysis reveals that charge is transferred to a fraction of 60% of the molecules in the complexes. [Copyright &y& Elsevier]

Abstract: A series of mono, tricyclic cyclophane tetraamides and cyclophane sulfonamides have been synthesized and characterized from spectral and XRD studies. All the cyclophane amides form charge transfer (CT) complex with TCNQ. The cyclophane amides show moderate to good anti-inflammatory activity. Some of them were active against Gram positive (Klebsiella pneumonia) and Gram negative (Escherichia coli and Staphylococcus aureus) human pathogens. [Copyright &y& Elsevier]

Abstract: We report the fabrication of ordered crystalline array of low molar-mass, soluble organic compounds (TCNQ, TTF) in large scale by a simple solution casting technique requiring no additional surface treatment. Different solvents and different processing conditions have been applied to find the optimum conditions for direct growth of the ordered crystalline arrays. Based on these crystalline arrays, organic field-effect transistors (OFETs) and photodetectors (PDs) have been fabricated which exhibited excellent device performances. TCNQ (TTF) based OFETs exhibited a low threshold voltage, high on/off current ratio (∼103) and a field-effect mobility as high as ∼0.02 (0.05)cm2 V−1 s−1. The ordered organic crystalline arrays, used in the fabrication of PDs, showed reproducible and reversible photoswitching characteristics with photo to dark current conversion ratio ∼40. This one-step, solution-based, self-assembly method for ordered array of different organic crystals in large area could have significant potential for future large-scale and low-cost optoelectronic devices. In addition, this study may encourage the researchers to synthesize and investigate for different organic materials capable of forming high quality nano/micro crystalline structures for various applications in plastic electronic devices. [Copyright &y& Elsevier]

Abstract: The reaction of π-conjugated poly(p-phenylene)s (PPPs) consisting of 2- or 3-amino-1,4-phenylene (NH2Ph) and 2,5-dioctyloxy-1,4-phenylene (OctPh) or 9,9-dihexylfluorene-2,7-diyl (HexFlu) rings [polymer-1: (NH2Ph-OctPh) n and polymer-2: (NH2Ph-HexFlu) n ] with 7,7,8,8-tetracyanoquinodimethane (TCNQ) yielded gel-1 and gel-2. These gels were form through a charge transfer (CT) between the NH2 group and TCNQ, causing the gels to be linked by a TCNQ dianion. ESR measurements suggest that radical species generated by CT in the gels are delocalized in the π-conjugated polymer backbone. UV–vis measurements revealed that CT between the NH2 group and TCNQ was essential for gel formation. When a dimethyl sulfoxide (DMSO)/TCNQ solution was added to a chloroform solution of the polymers, the absorption corresponding to CT bands increased with an increasing amount of TCNQ. Photoluminescence (PL) measurements suggested that TCNQ served as a quencher for fluorescent polymer-1 and polymer-2. Quenching behavior was investigated by Stern–Volmer analysis. [Copyright &y& Elsevier]

Abstract: A TCNQ-based triphenylamine derivative (1) with strong intramolecular charge transfer (ICT) character was designed as a colorimetric sensor for thiols. Upon addition of thiols, the absorption spectrum of sensor 1 in aqueous solution was remarkably changed because the adduct of 1 with thiol decreased its ICT character. Sensor 1 showed highly selective and sensitive sensing ability toward thiols over other analytes. This selectivity could be easily observed by naked eyes, indicating that sensor 1 is a potential colorimetric sensor for thiols. [Copyright &y& Elsevier]

Abstract: Electron donor acceptor complexes (EDA) of the 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6) as a rich donor were spectrophotometrically discussed and synthesized in solid form according the interactions with different nine of usual π-acceptors like 2,3,5,6-tetrachlorocyclohexa-2,5-diene-1,4-dione (p-chloranil; p-CHL), tetrachloro-1,2-benzoquinone (o-chloranil; o-CHL), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), tetracyanoquinodimethane (TCNQ), 2,6-dichloroquinone-4-chloroimide (DCQ), 2,6-dibromoquinone-4-chloroimide (DBQ), 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid; CLA), N-bromosuccinimide (NBS), 2,4,6-trinitrophenol (picric acid; PA). Spectroscopic and physical data such as formation constant (K CT), molar extinction coefficient (ɛ CT), standard free energy (ΔG°), oscillator strength (f), transition dipole moment (μ), resonance energy (R N) and ionization potential (I p) were estimated in chloroform or methanol at 25°C. Based on the elemental analysis and photometric titrations the CT-complexes were formed indicated the formation of 1:1 charge-transfer complexes for the o-CHL, TCNQ, DCQ, DBQ and NBS acceptors but 1:3 ratio for p-CHL, DDQ, CLA and PA, respectively. The charge-transfer interactions were interpretative according to the formation of dative ion pairs [18C6 +, A −], where A is acceptor. All of the resulting charge transfer complexes were isolated in amorphous form and the complexes formations on IR and 1H NMR spectra were discussed. [Copyright &y& Elsevier]

Abstract: Novel charge transfer complexes have been formed in the reaction of the interesting powerful electron donor 1,4,7,10,13,16-hexamethyl-1,4,7,10,13,16-hexaazacyclooctadecane (HMHACOD) with σ-electron acceptor iodine and π-acceptors tetracynoethylene (TCNE) and 7,7,8,8,-tetracyanoquinodimethane (TCNQ). The reactions have been studied spectrophotometrically in chloroform and the formed solid complexes have been isolated and characterized through infrared spectra as well as thermal and elemental analysis. Due to the expected powerful electron donation of the donor (HMHACOD), the reaction stoichiometries, donor:acceptor molar ratio values, are found to be exceptionally high equal to 1:6, 1:16 and 1:3 for iodine, TCNE and TCNQ complexes, respectively. Accordingly the formed charge transfer complexes could be formulated as [(HMHACOD)I]+·, [(HMHACOD)(TCNE)16] and [(HMHACOD)(TCNQ)3]. [Copyright &y& Elsevier]

Abstract: A colorimetric sensor based on dipyrromethane(donor)-7,7′,8,8′-tetracyanoquinodimethane (acceptor) charge-transfer compound depicts excellent selectivity for naked-eye as well as spectrophotometric determination of F− even in co-existence with other halide ions (Cl−, Br− and I−). The sensing mechanism is ascribed to the interrupted charge-transfer between donor–acceptor in the presence of F−. The sensing on solid support mimics the solution sensing process supported by the reflectance values. Thus this compound has potential for practical applications. [Copyright &y& Elsevier]

Abstract: 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 (ε). The solid CT complexes have been synthesized and characterization by different spectral methods. [ABSTRACT FROM AUTHOR]

Abstract: Reaction of N-methylpyrrole and 7,7,8,8-tetracyanoquinodimethane (TCNQ) furnishes an intense blue unsymmetrical charge-transfer compound through regioselective attachment of tricyanoquinodimethane at the 2-position of N-methylpyrrole which was found to be selective chemodosimeter for Hg2+ ions in CH3CN:H2O mixture (1:1 v/v, pH=7.0, 0.01M HEPES, 0.15M NaCl) as well as in the solid state when supported on silica, over a variety of metal ions. A plausible mechanism for the sensing process has been proposed and supported through the characterization of the resulting Hg2+ complex and the density functional theory (DFT) studies. [ABSTRACT FROM AUTHOR]