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The design and synthesis of organic photocatalysts remain a great challenge due to their strict structural constraints. However, this could be mitigated by achieving structural flexibility by constructing permanent porosity into the materials. Conjugated microporous polymers (CMPs) are an emerging class of porous materials with an amorphous, three-dimensional network structure, which makes it possible to integrate the elaborate functional groups to enhance photocatalytic performance. Here, we report the synthesis of a novel CMP, named TAPFc-TFPPy-CMP, constructed by 1,1′3,3′-tetra(4-aminophenyl)ferrocene (TAPFc) and 1,3,6,8-tetrakis(4-formylphenyl)pyrene (TFPPy) monomers. The integration of the p-type dopant 7,7,8,8-tetracyanoquinodimethane (TCNQ) into the TAPFc-TFPPy-CMP improved the light adsorption performance, leading to a decrease in the optical bandgap from 2.00 to 1.43 eV. The doped CMP (TCNQ@TAPFc-TFPPy-CMP) exhibited promising catalytic activity in photocatalytic CO2 reduction under visible light, yielding 546.8 μmol g−1 h−1 of CO with a selectivity of 96% and 5.2 μmol g−1 h−1 of CH4. This represented an 80% increase in the CO yield compared to the maternal TAPFc-TFPPy-CMP. The steady-state photoluminescence (PL) and fluorescence lifetime (FL) measurements reveal faster carrier separation and transport after the doping. This study provides guidance for the development of organic photocatalysts for the utilization of renewable energy. [ABSTRACT FROM AUTHOR]

The design and synthesis of organic photocatalysts remain a great challenge due to their strict structural constraints. However, this could be mitigated by achieving structural flexibility by constructing permanent porosity into the materials. Conjugated microporous polymers (CMPs) are an emerging class of porous materials with an amorphous, three-dimensional network structure, which makes it possible to integrate the elaborate functional groups to enhance photocatalytic performance. Here, we report the synthesis of a novel CMP, named TAPFc-TFPPy-CMP, constructed by 1,1′3,3′-tetra(4-aminophenyl)ferrocene (TAPFc) and 1,3,6,8-tetrakis(4-formylphenyl)pyrene (TFPPy) monomers. The integration of the p-type dopant 7,7,8,8-tetracyanoquinodimethane (TCNQ) into the TAPFc-TFPPy-CMP improved the light adsorption performance, leading to a decrease in the optical bandgap from 2.00 to 1.43 eV. The doped CMP (TCNQ@TAPFc-TFPPy-CMP) exhibited promising catalytic activity in photocatalytic CO2 reduction under visible light, yielding 546.8 μmol g−1 h−1 of CO with a selectivity of 96% and 5.2 μmol g−1 h−1 of CH4. This represented an 80% increase in the CO yield compared to the maternal TAPFc-TFPPy-CMP. The steady-state photoluminescence (PL) and fluorescence lifetime (FL) measurements reveal faster carrier separation and transport after the doping. This study provides guidance for the development of organic photocatalysts for the utilization of renewable energy.

A microfluid-assisted solution field-effect transistor (FET) with nanoscale channels of atomically thin MoS2 layers was constructed. The source–drain current (Id) vs gate voltage (Vg) characteristics (Id–Vg) were examined with a focus on the threshold voltage (Vth) at the onset of the Id–Vg curve. Id–Vg changed when the channel contacted the tetracyanoquinodimethane (TCNQ) and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) solutions in isopropyl alcohol (IPA), acetonitrile (ACN), and dimethyl sulfoxide (DMSO). The shift in Vth from the pure solvent condition (ΔVth) increased monotonically with the concentration, which was successfully simulated using Langmuir-type adsorption kinetics. We conclude that the TCNQ and F4-TCNQ solutes were partially solvated by the solvent and adsorbed on the MoS2 channel. Simultaneously, the saturated ΔVth value revealed a significant difference between the TCNQ and F4-TCNQ solutes. The ratio of saturated ΔVth of F4-TCNQ compared to that of TCNQ showed a decrease of 4.2, 1.7, and 1.3 for IPA, ACN, and DMSO, respectively. These results coincided with the order of the dielectric constants of these solvents (18.0, 36.0, and 46.6, respectively). The solutes produced the Id–Vg curve by both charge transfer and the gating effect, the latter of which was screened by the presence of a solvent. This study demonstrates that a solution FET can be employed in solid–solution interface chemistry. [ABSTRACT FROM AUTHOR]

Tetraphenylethene derivatives (TPEs) are used as luminescence probes for the detection of metal ions and biomolecules. These sensors function by monitoring the increase in the photoluminescence (PL) intensity of the TPEs resulting from aggregation-induced emission (AIE) upon interaction with the analytes. The AIE behavior of the sensors was investigated by measuring their PL. In this study, PL, PL lifetime, and confocal laser scanning microscopy measurements were carried out as part of our in-depth investigation of AIE behavior of TPEs for the detection of biomolecules and radical species. We used 1,1,2,2-tetrakis(4-((trimethylammonium)alkoxy)phenyl)tetraphenylethene tetrabromide (TPE-C(m)N+Me3Br−, m = 2, 4, and 6, where m denotes the number of methylene groups in the alkyl chain) and TPE-C(m)N+Me3TCNQ−• (TCNQ−• is the 7,7′,8,8′-tetracyanoquinodimethane anion radical) as luminescent probes for the detection of bovine serum albumin (BSA), DNA, and the hydroxyl radical (•OH) generated from Fenton's reagent. The sensing performance of TPE-C(m)N+Me3Br− for BSA and DNA was found to depend on the length of the alkyl chains (m). UV-vis and PL measurements revealed that the responses of TPE-C(m)N+Me3Br− and TPE-C(4)N+TCNQ−• to Fenton's reagent depended on the solvent. The electrochemical properties of the TPE derivatives prepared in this study were additionally investigated via cyclic voltammetry. [ABSTRACT FROM AUTHOR]

g-C3N4 and g-C3N4/TCNQ composites with different doping levels were prepared using the copolymerization thermal method with melamine as a precursor. XRD, FT-IR, SEM, TEM, DRS, PL, and I-T characterized them. The composites were successfully prepared in this study. The photocatalytic degradation of pefloxacin (PEF), enrofloxacin (ciprofloxacin), and ciprofloxacin (ciprofloxacin) under visible light (λ > 550 nm) showed that the composite material had the best degradation effect on PEF. When TCNQ doping is 20 mg and catalyst dosage is 50 mg, the catalytic effect is the best, and the degradation rate reaches 91.6%, k = 0.0111 min−1, which is four times that of g-C3N4. Repeated experiments found that the cyclic stability of the g-C3N4/TCNQ composite was good. The XRD images were almost unchanged after five reactions. The radical capture experiments revealed that ·O2− was the main active species in the g-C3N4/TCNQ catalytic system, and h+ also played a role in PEF degradation. And the possible mechanism for PEF degradation was speculated. [ABSTRACT FROM AUTHOR]

The TCNQ-rGO hybrid with connected conductive network exhibits the potential application in aqueous ammonium ion batteries. [Display omitted] Lithium-ion batteries (LIBs) have received much attention because of their environmental, financial, and safety concerns. The advantages of aqueous electrochemical energy storage include environmental friendliness and safety, and the development of prepared electrode materials is predicted to alleviate these issues. A redox-active organic compound, 7,7,8,8‑tetracyanoquinodimethane (TCNQ), is a suitable electrode for aqueous batteries. In this work, the porous and electronic interconnected structure of TCNQ is designed by electronic modulation and structure engineering. With the reduced graphene oxide (rGO) in situ homogeneous loading TCNQ by a one-step facile approach, the exquisite architecture has enhanced conductivity and connected conductive networks, favoring the storage and transportation of NH 4 + or electrons in aqueous electrolytes. As a cathode, the obtained TCNQ-rGO exhibits superior performance for NH 4 + batteries with an improved reversible capacity of 92.7 mAh/g at 1 A/g of quadruple capacity boosting to pure TCNQ and stable cycle life (5000 cycles at 10 A/g). The adjustment of the loading ratio of TCNQ and rGO for the cycling performance has been studied in detail. Furthermore, the superior ammonium storage mechanism of the TCNQ-rGO hybrid is thoroughly discussed by in situ Raman or ex situ measurements, which also determine the redox activity center groups of the TCNQ-rGO hybrid. Energy level calculations are conducted to help illustrate its potential as an electrode material. Our work demonstrates that electronic modulation and structural engineering of TCNQ can improve the electrochemical performance of molecular organic compound-based electrodes for aqueous rechargeable batteries in a simple and effective way. [ABSTRACT FROM AUTHOR]

An inexpensive, simple, sensitive and validated approach is developed for estimation of fingolimod through production of colored charge transfer complexes of fingolimod with different electron acceptor reagents, including a reaction of fingolimod as n-donor with 7,7,8,8-tetracyanoquinodimethane, tetrachloro 1,4-benzoquinone and tetracyanoethylene and as n-acceptors, yielding colored and stable anions which were measured spectrophotometrically. The range that obeyed Beer's law is 50–300 µg mL−1 for fingolimod with all the studied reagents. The various parameters that affect the reaction were studied and optimized. The results were statistically compared with a reported method showing equal precision and accuracy. The researched approaches were utilized to determine the cited drug in its pharmaceutical form and spiked human plasma with accepted accuracy and precision. [ABSTRACT FROM AUTHOR]

Tetraphenylethene derivatives (TPEs) are used as luminescence probes for the detection of metal ions and biomolecules. These sensors function by monitoring the increase in the photoluminescence (PL) intensity of the TPEs resulting from aggregation-induced emission (AIE) upon interaction with the analytes. The AIE behavior of the sensors was investigated by measuring their PL. In this study, PL, PL lifetime, and confocal laser scanning microscopy measurements were carried out as part of our in-depth investigation of AIE behavior of TPEs for the detection of biomolecules and radical species. We used 1,1,2,2-tetrakis(4-((trimethylammonium)alkoxy)phenyl)tetraphenylethene tetrabromide (TPE-C(m)N+Me3Br−, m = 2, 4, and 6, where m denotes the number of methylene groups in the alkyl chain) and TPE-C(m)N+Me3TCNQ−• (TCNQ−• is the 7,7′,8,8′-tetracyanoquinodimethane anion radical) as luminescent probes for the detection of bovine serum albumin (BSA), DNA, and the hydroxyl radical (•OH) generated from Fenton’s reagent. The sensing performance of TPE-C(m)N+Me3Br− for BSA and DNA was found to depend on the length of the alkyl chains (m). UV-vis and PL measurements revealed that the responses of TPE-C(m)N+Me3Br− and TPE-C(4)N+TCNQ−• to Fenton’s reagent depended on the solvent. The electrochemical properties of the TPE derivatives prepared in this study were additionally investigated via cyclic voltammetry.

A poly(vinyl pyrrolidone) (PVP)/Ag nanoparticles (AgNPs)/7,7,8,8-Tetracyanoquinodimethane (TCNQ)/dioctyl phthalate (DOP) composite membrane using positively charged silver nanoparticles was prepared for CO2 separation. Positively polarized silver nanoparticles were generated by TCNQ, known as an electron acceptor for CO2 carrier. In the separation of CO2 and N2, the composite membrane consisting of PVP/AgNPs/TCNQ/DOP showed that only polar CO2 could be selectively separated by a reversible reaction with the positively polarized silver nanoparticles. Furthermore, the addition of DOP as a plasticizer enhanced gas permeance through the glassy PVP, and the CO2/N2 selectivity performance reached 103.8. The PVP/AgNPs/TCNQ/DOP composite membranes were characterized by FTIR spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and scanning electron microscopy. [ABSTRACT FROM AUTHOR]

Tigecycline (TIGC) reacts with 7,7,8,8-tetracyanoquinodimethane (TCNQ) to form a bright green charge transfer complex (CTC). The spectrum of the CTC showed multiple charge transfer bands with a major peak at 843 nm. The Plackett–Burman design (PBD) was used to investigate the process variables with the objective being set to obtaining the maximum absorbance and thus sensitivity. Four variables, three of which were numerical (temperature—Temp; reagent volume—RV; reaction time—RT) and one non-numerical (diluting solvent—DS), were studied. The maximum absorbance was achieved using a factorial blend of Temp: 25 °C, RV: 0.50 mL, RT: 60 min, and acetonitrile (ACN) as a DS. The molecular composition that was investigated using Job's method showed a 1:1 CTC. The method's validation was performed following the International Conference of Harmonization (ICH) guidelines. The linearity was achieved over a range of 0.5–10 µg mL−1 with the limits of detection (LOD) and quantification (LOQ) of 166 and 504 ng mL−1, respectively. The method was applicable to TIGC per se and in formulations without interferences from common additives. The application of the Benesi–Hildebrand equation revealed the formation of a stable complex with a standard Gibbs free energy change (∆G°) value of −26.42 to −27.95 kJ/mol. A study of the reaction kinetics revealed that the CTC formation could be best described using a pseudo-first-order reaction. [ABSTRACT FROM AUTHOR]

g-C3N4 and g-C3N4/TCNQ composites with different doping levels were prepared using the copolymerization thermal method with melamine as a precursor. XRD, FT-IR, SEM, TEM, DRS, PL, and I-T characterized them. The composites were successfully prepared in this study. The photocatalytic degradation of pefloxacin (PEF), enrofloxacin (ciprofloxacin), and ciprofloxacin (ciprofloxacin) under visible light (λ > 550 nm) showed that the composite material had the best degradation effect on PEF. When TCNQ doping is 20 mg and catalyst dosage is 50 mg, the catalytic effect is the best, and the degradation rate reaches 91.6%, k = 0.0111 min−1, which is four times that of g-C3N4. Repeated experiments found that the cyclic stability of the g-C3N4/TCNQ composite was good. The XRD images were almost unchanged after five reactions. The radical capture experiments revealed that ·O2− was the main active species in the g-C3N4/TCNQ catalytic system, and h+ also played a role in PEF degradation. And the possible mechanism for PEF degradation was speculated.

Summary: Until now, in case of Li‐O2 batteries, catalyst materials are applied by simple mixing with carbon black, which causes large overpotential due to limited active surface of the catalyst, leading to low energy efficiency and short cycle life. Accordingly, in previous studies, significant advances have been witnessed in the synthesis of various electrode materials with three‐dimensional (3‐D) structures for application in electrochemical energy storage devices. Herein, the 1‐D@3‐D catalyst layer design and efficient active site formation strategy help to enable an efficient Li‐O2 battery. In particular, it should be noted that the 1‐D@3‐D catalyst layer has great potential for maximizing the active contact area between the electrolyte and the catalyst materials and promoting the rapid diffusion of products and reactants through their stereoscopic structure. The 1‐D Ru‐doped CuO nanorod array on 3‐D carbon cloth (Ru‐CuO/RuO2@CC) is demonstrated via 7,7,8,8‐Tetracyanoquinodimethane‐solution deposition, and thermal oxidation process. A comprehensive kinetic study using linear sweep voltammetry reveals that the Ru‐CuO/RuO2@CC has superior ORR/OER performance compared to a CuO nanorods‐loaded carbon cloth and a CuO/RuO2 nanoparticles‐loaded carbon cloth. The Ru‐CuO/RuO2@CC as a catalyst layer combined cell is achieved 1.0 mA h cm−2 (=3075 mA h gc−1) during 30 cycles with a low overpotential decay rate of 0.88% per cycle. [ABSTRACT FROM AUTHOR]

Objective:Two simple, rapid and sensitive methods were developed for determination of Erdosteine (ERD) in pure form as well as in their pharmaceutical formulations.Methods:The methods were based on formation of colored charge transfer complexes with ERD with chloranil (CA) and 7,7,8,8-tetracyanoquinodimethane (TCNQ). The obtained charge-transfer complexes were measured at 454 and 843 nm for CA and TCNQ methods, respectively. Optimization of different experimental conditions were investigated.Results:Beer’s plots were obeyed in a general concentration range of 10-500 μg mL-1 and 20-600 μg mL-1 for CA and TCNQ methods, respectively. The validity of methods in terms of specificity, linearity, accuracy, precision, limit of detection and limit of quantitation were evaluated.Conclusion:The methods were applied successfully in the determination of ERD in capsule dosage forms. Developed new spectrophotometric methods have been found to be very practical and practical. The lack of complex sample preparation increases the applicability of the method.

The molecular charge transfer reactions of quinine (Q) with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as a π-acceptor to form charge transfer (CT) complexes have been studied. The CT complexes were characterized by infrared spectra, NMR, mass spectrometry, conductometry and spectrometry. The Q-DDQ and Q-TCNQ charge transfer complexes were monitored at 480 and 843 nm, respectively. The results confirm the formation of CT complexes. The molar ratio of Q:DDQ and Q: TCNQ assessed using Job's method was 1:1, which agrees with the results obtained by the Benesi-Hildebrand equation. The stability of the formed CT complexes was assessed by measuring different spectroscopic parameters such as oscillator strength, transition dipole moment, ionization potential, the energy of CT complex, resonance energy, dissociation energy and standard free energy change. The DFT geometry optimization of quinine, DDQ and TCNQ, its charge transfer complex, and UV theoretical vs. experimental comparative study were carried out. The theoretical and experimental results agreed. DFT/B3LYP/6-311++G(d,p) level of theory was used for the investigation of charge transfer between quinine as electron donor and (DDQ and TNCQ) as electron acceptors. The geometric structures, orbital energies, HOMO, LUMO and energy gaps were determined. The transition energies of the charge transfer complexes were computed using the TD-DFT/B3LYP/6-311++G(d,p) level of theory. The computed parameters were comparable to the experimental parameters, and the computational results aided in the analysis of the data. [ABSTRACT FROM AUTHOR]

Recently, the flexibility of 2D conductive metal–organic frameworks (MOFs) is an important precondition for manufacturing high‐performance smart electronic devices. Preparation of MOFs thin film has drawn much attention, and increasingly more MOF thin films have been deposited on different rigid substrates like glass, silicon, and metal electrodes. However, they do not meet the requirements for flexible materials, such as wearable electronic devices. Here, the fabric‐based composites (the integration of MOFs and fabric materials) can solve this problem. Insulating polyester fabric is chosen as a flexible substrate and atom layer deposition (ALD) and the layer‐by‐layer (LBL) method (also called the liquid phase epitaxy method) are combined to synthesize Cu3(BTC)2 thin film. 7,7,8,8‐tetracyanoquinodimethane (TCNQ) and polypyrrole (PPy) are chosen to improve the conductivity of the MOF thin films. The conductivity of Cu3(BTC)2 thin film is improved by more than four orders of magnitude compared to that of the original sample. This research shows that the large‐area lightweight fabric‐based Cu3(BTC)2 thin films, which possess excellent uniformity and flexibility and controllable thickness, can be prepared at room temperature; this allows MOFs to be applied in more areas, such as large‐area electronic devices and smart wearable sensing equipment. [ABSTRACT FROM AUTHOR]

The effect of molecular adsorption on the electronic properties of siligraphene sheets is investigated through density functional theory (DFT) calculations. Adsorption of the organic molecules tetracyanoethylene (TCNE), tetrathiafulvalene (TTF), as well as tetracyanoquinodimethane (TCNQ) on siligraphene (SiCx with x = 1, 2, 3, 5 and 7) is studied. The three types of SiCx: SiC, SiC2 and SiC7 have semiconductor properties, while SiC3 and SiC5 are semimetals. P-type and n-type semiconductors are obtained via charge transfer between the organic molecules and SiCx sheets. The SiC, SiC2 and SiC7 sheets exhibit p-type semiconductor behaviour after TCNE and TCNQ adsorption, while they exhibit n-type semiconductor behaviour due to TTF adsorption. The adsorbed molecules have no significant effect on the band gap energy of SiC3 and SiC5. The results provide an effective method to model the electronic properties of siligraphene sheets. [ABSTRACT FROM AUTHOR]

Donor–acceptor type polymers and supramolecules are promising electrets in photonic field‐effect transistor (FET)‐type memory because of their diversified polymer‐structure design and favorable mechanical tolerance. Using intermolecular association, supramolecule electrets can surpass donor–acceptor type polymers with versatile facile combining processes. Currently, there has been no application of charge‐transfer (CT) supramolecules in electrets of photonic FET memory devices. Herein, a novel series of CT‐based supramolecular electrets comprising poly(1‐pyrenemethyl methacrylate) (PPyMA) and 7,7,8,8‐tetracyanoquinodimethane (TCNQ) is used to elucidate the effect of CT on photonic FET memory. Accordingly, memory devices based on the supramolecular electret with an equimolar content of pyrene and TCNQ exhibit superior bistable memory switchability using electrical/photoprograming with UV (365 nm) and green light (525 nm). This shows a broad memory window of 34 V and favorable memory ratio of over 106 after 104 s. The memory performance can be attributed to the favorable molecular association and dispersion between pyrene and TCNQ in the solid state. The results provide evidence that CT‐based supramolecular electrets warrant applications in optoelectronic applications. [ABSTRACT FROM AUTHOR]

Benzo[1,2-c:3,4-c′:5,6-c′′]trithiophene (D3h-BTT) is an easily prepared electron donor that readily forms charge–transfer complexes with organic acceptors. We report here two crystal structures of its charge–transfer complexes with 7,7,8,8-tetracyanoquinodimethane (TCNQ) and buckminsterfullerene (C60). The D3h-BTT·TCNQ complex, C12H6S3·C12H4N4, crystallizes with mixed layers of donors and acceptors, with an estimated degree of charge transfer at 0.09 e. In the D3h-BTT·C60·toluene complex, C12H6S3·C60·C7H8, the central ring of BTT is `squeezed' by the C60 molecules from both faces. However, the degree of charge transfer is low. The C60 unit is disordered over two sites in a 0.766 (3):0.234 (3) ratio and was refined as a two-component inversion twin.

Tigecycline (TIGC) reacts with 7,7,8,8-tetracyanoquinodimethane (TCNQ) to form a bright green charge transfer complex (CTC). The spectrum of the CTC showed multiple charge transfer bands with a major peak at 843 nm. The Plackett–Burman design (PBD) was used to investigate the process variables with the objective being set to obtaining the maximum absorbance and thus sensitivity. Four variables, three of which were numerical (temperature—Temp; reagent volume—RV; reaction time—RT) and one non-numerical (diluting solvent—DS), were studied. The maximum absorbance was achieved using a factorial blend of Temp: 25 °C, RV: 0.50 mL, RT: 60 min, and acetonitrile (ACN) as a DS. The molecular composition that was investigated using Job’s method showed a 1:1 CTC. The method’s validation was performed following the International Conference of Harmonization (ICH) guidelines. The linearity was achieved over a range of 0.5–10 µg mL−1 with the limits of detection (LOD) and quantification (LOQ) of 166 and 504 ng mL−1, respectively. The method was applicable to TIGC per se and in formulations without interferences from common additives. The application of the Benesi–Hildebrand equation revealed the formation of a stable complex with a standard Gibbs free energy change (∆G°) value of −26.42 to −27.95 kJ/mol. A study of the reaction kinetics revealed that the CTC formation could be best described using a pseudo-first-order reaction.

• 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]

Objective: Two simple, rapid and sensitive methods were developed for determination of Erdosteine (ERD) in pure form as well as in their pharmaceutical formulations. Methods: The methods were based on formation of colored charge transfer complexes with ERD with chloranil (CA) and 7,7,8,8-tetracyanoquinodimethane (TCNQ). The obtained charge-transfer complexes were measured at 454 and 843 nm for CA and TCNQ methods, respectively. Optimization of different experimental conditions were investigated. Results: Beer's plots were obeyed in a general concentration range of 10-500 µg mL-1 and 20-600 µg mL-1 for CA and TCNQ methods, respectively. The validity of methods in terms of specificity, linearity, accuracy, precision, limit of detection and limit of quantitation were evaluated. Conclusion: The methods were applied successfully in the determination of ERD in capsule dosage forms. Developed new spectrophotometric methods have been found to be very practical and practical. The lack of complex sample preparation increases the applicability of the method. [ABSTRACT FROM AUTHOR]

Abstract The fundamental properties and applications of organic charge transfer complexes based on Pb(TCNQ)2 (Pb = lead, TCNQ = 7,7,8,8‐tetracyanoquinodimethane) and its fluorinated derivatives are relatively unknown. Here, a facile solid–liquid approach for the synthesis of Pb(TCNQ)2 and Pb(TCNQF4)2 is reported. These materials are thoroughly analyzed to obtain insights into their unique morphological, vibrational and optical properties, the latter extending across the UV–Vis–IR region. Subsequently, the catalytic potential of these materials is evaluated by employing a model redox reaction, which revealed two orders of magnitude higher catalytic activity of the fluorinated derivative over non‐fluorinated Pb(TCNQ)2 crystals. Overall, the work presented here adds a new member to the growing yet limited library of metal–organic charge transfer complexes and validates the outstanding redox catalysis performance of this group of materials.

The molecular charge transfer reactions of quinine (Q) with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as a π-acceptor to form charge transfer (CT) complexes have been studied. The CT complexes were characterized by infrared spectra, NMR, mass spectrometry, conductometry and spectrometry. The Q-DDQ and Q-TCNQ charge transfer complexes were monitored at 480 and 843 nm, respectively. The results confirm the formation of CT complexes. The molar ratio of Q:DDQ and Q: TCNQ assessed using Job’s method was 1:1, which agrees with the results obtained by the Benesi-Hildebrand equation. The stability of the formed CT complexes was assessed by measuring different spectroscopic parameters such as oscillator strength, transition dipole moment, ionization potential, the energy of CT complex, resonance energy, dissociation energy and standard free energy change. The DFT geometry optimization of quinine, DDQ and TCNQ, its charge transfer complex, and UV theoretical vs. experimental comparative study were carried out. The theoretical and experimental results agreed. DFT/B3LYP/6-311++G(d,p) level of theory was used for the investigation of charge transfer between quinine as electron donor and (DDQ and TNCQ) as electron acceptors. The geometric structures, orbital energies, HOMO, LUMO and energy gaps were determined. The transition energies of the charge transfer complexes were computed using the TD-DFT/B3LYP/6-311++G(d,p) level of theory. The computed parameters were comparable to the experimental parameters, and the computational results aided in the analysis of the data.

The fundamental properties and applications of organic charge transfer complexes based on Pb(TCNQ)2 (Pb = lead, TCNQ = 7,7,8,8‐tetracyanoquinodimethane) and its fluorinated derivatives are relatively unknown. Here, a facile solid–liquid approach for the synthesis of Pb(TCNQ)2 and Pb(TCNQF4)2 is reported. These materials are thoroughly analyzed to obtain insights into their unique morphological, vibrational and optical properties, the latter extending across the UV–Vis–IR region. Subsequently, the catalytic potential of these materials is evaluated by employing a model redox reaction, which revealed two orders of magnitude higher catalytic activity of the fluorinated derivative over non‐fluorinated Pb(TCNQ)2 crystals. Overall, the work presented here adds a new member to the growing yet limited library of metal–organic charge transfer complexes and validates the outstanding redox catalysis performance of this group of materials. [ABSTRACT FROM AUTHOR]

The reaction of Fe(OAc)2 and Hbpypz with neutral TCNQ results in the formation of [Fe2(bpypz)2(TCNQ)2](TCNQ)2 (1), in which Hbpypz=3,5‐bis(2‐pyridyl)pyrazole and TCNQ=7,7′,8,8′‐tetracyano‐p‐quinodimethane. Crystal packing of 1 with uncoordinated TCNQ and π–π stacking of bpypz− ligands produces an extended two‐dimensional supramolecular coordination assembly. Temperature dependence of the dc magnetic susceptibility and heat capacity measurements indicate that 1 undergoes an abrupt spin crossover (SCO) with thermal spin transition temperatures of 339 and 337 K for the heating and cooling modes, respectively, resulting in a thermal hysteresis of 2 K. Remarkably, the temperature dependence of dc electrical transport exhibits a transition that coincides with thermal SCO, demonstrating the thermally induced magnetic and electrical bistability of 1, strongly correlating magnetism with electrical conductivity. This outstanding feature leads to thermally induced simultaneous switching of magnetism and electrical conductivity and a magnetoresistance effect. [ABSTRACT FROM AUTHOR]

Background: The problem of detecting the different strains of H. pylori has gained great importance today due to the worldwide prevalence of this bacterium and its role in the pathogenesis of a number of serious gastric and extragastric diseases. However, not all H. pylori strains are aggressive and require antibiotic treatment. Thus, the question arises about the necessity of differentiating these bacterium strains with respect to their virulence factors. In accordance with the IV Maastricht Consensus Report, among the variety of ways to diagnose H. pylori infection, non-invasive methods should be given preference. Most of them are based on the analysis of gas which is exhaled by a human. Mass spectrometry, gas chromatography, and IR spectroscopy are currently the mostly used ones. However, despite the obvious advantages, these techniques have a number of disadvantages that make them difficult to use in everyday medical practice. Modern sensor devices can become an inexpensive and easy to access alternative to these technologies. Objectives: The aim of the work is to develop a new type of sensor device for selective recognition of H. pylori strains which is based on analysis of a mixture of gases exhaled by human. Such a kind of device can be designed on the basis of a point-contact gas sensor. Materials and methods: Anion-radical salts of the organic conductor TCNQ were chosen as the sensitive material for point-contact sensors. The fundamental properties of point contacts which are used in the Yanson point-contact spectroscopy make it possible to create a point-contact mesoscopic matrix on the basis of this material, which is sensitive to small concentrations of components in complex gas media. The sensors were obtained by electrochemical deposition of salts from a solvent characterized by a high vapor pressure on a textolite substrate. Gas exhaled by a human served as the substance to be analyzed. The measurements were carried out following a specially developed technique. The sensor response curves were recorded by a measuring complex and original software designed by the authors. Results: A set of 350 active-type TCNQ-based sensors was studied under the influence of a mixture of breath gases. Gas-sensitive sensors based on TCNQ compounds are characterized by a complex response curve with two extrema. Since the temporal variation in electrical conductivity of the sensor correlates well with the dependence of its resistance on the energy of the adsorbed components of the gas mixture, the resulting response curves of point-contact sensors can be called spectral profiles of a complex gas mixture. It is possible to differentiate among the various states of human body caused by the H. pylori bacterium by using spectral profiles of the gas exhaled by different patients. As a result, the developed sensors were shown to be an effective tool for analyzing breath gas exhaled in real time mode. They demonstrated a high sensitivity and selectivity to the products of activity of different H. pylori strains. Conclusions: It was shown that the products of metabolism of carcinogenic H. pylori strains had a dominant influence on electrical conductivity of the sensor and thus shaped the behavior of the features on sensor response curves. As a result, it is possible to differentiate H. pylori strains with respect to their carcinogenic potential using point-contact sensors based on TCNQ compounds. Thus, an effective portable tool was created in this work for the first time to develop innovative screening technologies for non-invasive diagnosis of human body conditions characterized by gastroduodenal pathology and to distinguish carcinogenic strains of H. pylori from tolerant ones.

Benzo[1,2-c:3,4-c′:5,6-c′′]tri­thio­phene (D3h-BTT) is an easily prepared electron donor that readily forms charge–transfer complexes with organic acceptors. We report here two crystal structures of its charge–transfer complexes with 7,7,8,8-tetra­cyano­quinodi­methane (TCNQ) and buckminsterfullerene (C60). The D3h-BTT·TCNQ complex, C12H6S3·C12H4N4, crystallizes with mixed layers of donors and acceptors, with an estimated degree of charge transfer at 0.09 e. In the D3h-BTT·C60·toluene complex, C12H6S3·C60·C7H8, the central ring of BTT is `squeezed' by the C60 mol­ecules from both faces. However, the degree of charge transfer is low. The C60 unit is disordered over two sites in a 0.766 (3):0.234 (3) ratio and was refined as a two-component inversion twin. [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]

The reactions of ketotifen fumarate (KT) with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as π acceptors to form charge transfer (CT) complexes were evaluated in this study. Experimental and theoretical approaches, including density function theory (DFT), were used to obtain the comprehensive, reliable, and accurate structure elucidation of the developed CT complexes. The CT complexes (KT-DDQ and KT-TCNQ) were monitored at 485 and 843 nm, respectively, and the calibration curve ranged from 10 to 100 ppm for KT-DDQ and 2.5 to 40 ppm for KT-TCNQ. The spectrophotometric methods were validated for the determination of KT, and the stability of the CT complexes was assessed by studying the corresponding spectroscopic physical parameters. The molar ratio of KT:DDQ and KT:TCNQ was estimated at 1:1 using Job’s method, which was compatible with the results obtained using the Benesi–Hildebrand equation. Using these complexes, the quantitative determination of KT in its dosage form was successful.

Kinesin-5 inhibitörü olarak kullanılan Monastrol, çözücüsüz ortamda alümina sülfonik asit (ASA) katalizörü varlığında 3-hidroksibenzaldehit, tiyoüre ve etilasetoasetat kullanılarak sentezlenmiştir. Elektron verici (Donör, D) olarak monastrol, elektron alıcı (Akseptör, A) olarak tetrasiyanoquinometan (TCNQ) kullanılmış ve bunlar ile 2,3-dikloro-5,6-disiyano-p-benzokinon (DDQ) bileşikleri arasındaki yük transfer kompleksleri asetonitril içinde 21 °C'de spektrofotometrik olarak incelenmiştir. Komplekslerin stokiyometrisi, Job yöntemi kullanılarak incelenmiş, elektron verici ve alıcılar arasında TCNQ ile 742 nm ve DDQ ile 546 nm dalga boyunda maksimum absorbsiyon bandında 1:1 oranında olduğu bulunmuştur. Komplekslerin denge sabiti Benesi-Hildebrand ve termodinamik parametreleri Van't Hoff denklemi ile belirlenmiştir.

The two-dimensional electron system (2DES) located at the surface of strontium titanate (STO) and at several other STO-based interfaces has been an established platform for the study of novel physical phenomena since its discovery. Here we report how the interfacing of STO and tetracyanoquinodimethane (TCNQ) results in a charge transfer that depletes the number of free carriers at the STO surface, with a strong impact on its electronic structure. Our study paves the way for efficient tuning of the electronic properties, which promises novel applications in the framework of oxide/organic-based electronics.

Tetracyanoquinodimethane (TCNQ) electrode material has achieved excellent performance in aqueous zinc-ion batteries (AZIBs). However, fundamental understanding about effect of substitutes on electrochemical performance of TCNQ remain unknown. In this work, the effects of fluorine (F) as an electron-absorbing group on the structure, morphology and electrochemical performance of TCNQ and storage mechanism of TCNQ in AZIBs are discussed. Theoretical calculation proves that the introduction of fluorine atoms decreases lowest unoccupied molecular orbital (LUMO) energy of TCNQ thus affect the redox potential. Electrochemical performance of TCNQ/Fluoro-7,7,8,8-tetracyanoquinodimethane (FTCNQ)/2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F 4 TCNQ) is evaluated from 25 °C to -20 °C in AZIBs. Results tend out that with the increasing substituents of F on TCNQ molecular, their stability in AZIBs decrease. Dipole moment calculation further shows that the introduction of fluorine atoms is inconducive to the stability of the electrode material in aqueous solution. Ex-situ characterization demonstrate that electron withdrawing groups do not change the REDOX center of TCNQ electrode materials. Our work provides a new thought for the selection of the electrode material in AZIBs., (© 2023 Wiley-VCH GmbH.)

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]

The cyanocarbons tetracyanoethylene (TCNE) and tetracyanoquinodimethane (TCNQ) are important electron acceptors used in organic electronic applications. A common approach to enhancing their performance is by structural modification with previous studies focusing on substituting the cyano ligands or annular moiety. In this work, we assess the effect of hypovalent substitution, swapping carbon for silicon, on the potential energy surfaces and adiabatic electron affinities (AEAs). Si-substitution generally enhances AEA, and in the case of TCNQ stabilizes an open-shell singlet diradical state. Such findings may find value in the design of new materials based on the cyanocarbon platform. [ABSTRACT FROM AUTHOR]

In this study, the nature and characteristics of the intramolecular and intermolecular interactions in crystal structures of the fluoro‐substituted 7,7,8,8‐tetracyanoquinodimethane (TCNQ) family of molecules, i.e. Fx‐TCNQ (x = 0, 2, 4), are explored. The molecular geometry of the reported crystal structures is directly dependent on the degree of fluorination in the molecule, which consequently also results in the presence of an intramolecular N[triple‐bond]C...F—C π‐hole tetrel bond. Apart from this, the energy framework analysis performed along the respective transport planes provides new insights into the energetic distribution in this class of molecules. Charge density and energy framework analysis provide quantitative insights into the relevance of intermolecular interactions and transport properties in the fluoro‐substituted TCNQ family of molecules. [ABSTRACT FROM AUTHOR]

Understanding the solvation and ion-pairing interactions of anionic substrates in room-temperature ionic liquids (RTIL) is key for the electrochemical applications of these new classes of solvents. In this work, cyclic voltammetry and visible and infrared spectroelectrochemistry of tetracyanoquinodimethane (TCNQ) was examined in molecular (acetonitrile) and RTIL solvents, as well as mixtures of these solvents. The overall results were consistent with the formation of RTIL/acetonitrile nanodomains. The voltammetry indicated that the first electrogenerated product, TCNQ−, was not incorporated into the RTIL nanodomain, while the second electrogenerated product, TCNQ2−, was strongly attracted to the RTIL nanodomain. The visible spectroelectrochemistry was also consistent with these observations. Infrared spectroelectrochemistry showed no discrete ion pairing between the cation and TCNQ− in either the acetonitrile or RTIL solutions. Discrete ion pairing was, however, observed in the acetonitrile domain between the tetrabutylammonium ion and TCNQ2−. On the other hand, no discrete ion pairing was observed in BMImPF6 or BMImBF4 solutions with TCNQ2−. In BMImNTf2, however, discrete ion pairs were formed with BMIm+ and TCNQ2−. Density function theory (DFT) calculations showed that the cations paired above and below the aromatic ring. The results of this work support the understanding of the redox chemistry in RTIL solutions.

Helical organic micro- and nanostructures are formed by a charge-transfer complex, cinchonidine-TCNQ. These unusual forms result from the chirality, the steric structure and specific interactions of cinchonidine molecules. These materials are semiconductors (10−4 S cm−1), with the typical absorption spectra in IR and UV-vis, but also have a characteristic of CD spectrum. Surprisingly, conductive micro and nano helices are not formed in pseudo-enantiomeric cinchonine, i.e. the complex of cinchonine and TCNQ.

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]

The puckered surface of black phosphorus represents an ideal substrate for an unconventional arrangement of physisorbed species and the resulting specific two‐dimensional chemistry of this system. This opens the way to investigate the chemical and physical properties of locally confined areas of black phosphorus without the necessity for further physical downscaling of the material. We have evaporated tetracyanoquinodimethane (TCNQ) on top of black phosphorus under over‐saturation non‐equilibrium conditions in vacuum. The evolution of linear density and height of droplets formed through oxidation during exposure to air is studied time dependently by scanning‐force microscopy. Our study suggests that the TCNQ molecules spontaneously arrange in a thin layer of the order of a few nm height, which, however, is fragmented with a periodicity of about 100 nm. It is shown that within the confined space separating the layer fragments the chemical dynamics of the oxidation process is remarkably different than on a bare black phosphorus surface. [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]

Carbazole Substituted Pyridopyrimidine (CSPP) was synthesized and Charge transfer complexes with some acceptors such as tetracyanoquinomethane (TCNQ) and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) have been studied spectrophotometrically in acetonitrile at 21°C. The stoichiometries of the complexes were found to be 1:1 ratio by the Job method between donor and acceptors with the maximum absorption band at a wavelength of 715 nm for DDQ and 593 nm for TCNQ. The formation constants of the complexes were determined by Benesi-Hildebrand equation. The thermodynamic parameters were calculated by Van't Hoff equations and found spontaneous and exothermic. [ABSTRACT FROM AUTHOR]

In this paper, a AgI@TCNQ photocatalyst with a core-shell structure was reported. A two-dimensional TCNQ (7,7,8,8-Tetracyanoquinodimethane) nanosheet, with a π-π conjugate structure, was used as a shell layer to realize the flexible coating on the surface of AgI nanoparticles. These special core-shell structure composites solve the key problems of the small interface of the bulk composites and the lesser charge transfer paths, which could accelerate the migration of photogenerated carriers. Thus, the AgI@TCNQ photocatalysts showed the better photodegradation performance for the methylene blue (MB) solution, and the degradation rate of AgI@TCNQ (1 wt.%) composite was 1.8 times than AgI under irradiation. The reactive species trapping experiments demonstrated that ·O2−, h+, and ·OH all participated in the MB degradation process. The photocatalytic mechanism of AgI@TCNQ composites could be rationally explained by considering the Z-scheme structure, resulting in a higher redox potential and more efficient separation of charge carriers. At the same time, the unique core-shell structure provides a larger contact area, expands the charge transport channel, and increases the surface active sites, which are beneficial for improving photocatalytic performance.