Tetracyanoethylene Research Articles

Structure and Physical Properties of Alternately Stacked Donor-acceptor Complexes with 5,11-Dimethyl-5,11-dihydroindolo[3,2-b]carbazole

Alternately stacked donor-acceptor (DA) complexes containing 5,11-dimethyl-5,11-dihydroindolo[3,2-b]carbazole (ICZ-Me) as a donor were synthesized for the first time by crystallization with three different acceptor molecules. Among them, the DA complex with tetracyanoethylene (TCNE) exhibited the largest effective charge transfer integral (|tDA|), degree of charge transfer (ρ), and electrical conductivity (σ). Designing the noncovalent interaction is important to fix the position of acceptors with respect to ICZ-Me and to control the electronic properties. Alternately stacked donor-acceptor (DA) complexes containing 5,11-dimethyl-5,11-dihydroindolo[3,2-b]carbazole (ICZ-Me) as a donor component were synthesized with three different acceptor molecules. The DA complex with tetracyanoethylene (TCNE) exhibited the largest effective charge transfer integral, degree of charge transfer and electrical conductivity, indicating the importance of designing appropriate noncovalent interaction among molecules for optimizing their electronic properties.

Construction of fluorescence system of felodipine–tetracyanovinyl–2,2′-bipyridine complex

Abstract Felodipine (FEL)–tetracyanoethylene (TCNE)–2,2′-bipyridine (Bpy) complex was prepared with FEL, TCNE–Bpy and characterized by fluorescence, ultraviolet, and infrared. By exploring the concentration and dosage of Bpy, it was found that 1 mL 2 × 10−3 mol‧L−1 of Bpy had the best effect. The sequence of reagent addition was determined to be followed by FEL, then by TCNE, and then followed by Bpy. The concentration of FEL was 2.5 × 10−4 to 9.0 × 10−3 mol‧L−1, which had a good linear relationship with fluorescence intensity. The compound had good accuracy, precision, and specificity, and could be used for the determination of phelodipine content in FEL sustained-release tablets.

A comprehensive study of tetracyanobutadiene push-pull chromophores derived from γ-pyranylidene

A new class of push-pull 1,1,4,4-tetracyanobutadienes (TCBDs) chromophores bearing a γ-pyranylidene as a pro-aromatic donor group have been developed, characterized and studied for their electrochemical, photophysical and second-order nonlinear optical (NLO) properties. [2 ​+ ​2] Cycloaddition-retroelectrocyclizations (CA-RE) with tetracyanoethylene (TCNE) allowed the formation of new TCBDs by taking advantage of the electron-donating ability of γ-pyranylidene functional groups. The limits of the reaction between TCNE and the corresponding alkynes have been investigated, both in terms of reactivity and solubility. Electrochemical studies of pyranylidene-TCBD 1a-1j revealed two reversible reduction waves typical of TCBDs, and two oxidation waves originating from the γ-pyranylidene moiety. More complex electrochemical signals have been recorded when studying chromophores bearing multiple TCBD and/or γ-pyranylidene units. All pyranylidene-TCBDs showed panchromatic absorption properties, extending to the NIR in some cases. Changes made around the electron-withdrawing TCBD units significantly affected the ICT performance of the push-pull chromophores. Computational studies have been performed on this series of compounds to rationalize the origin of their optical properties. TD-DFT calculations confirmed that the synthesized pyranylidene-TCBDs are potential NLOphores. The second-order NLO properties of all chromophores were determined by the Electric Field-Induced Second Harmonic generation (EFISH) technique, and all systems exhibited valuable NLO properties with large μβEFISH values for purely organic compounds, up to 5700 10−48 ​esu.

Synthesis of tetrazine-tetracyanobutadienes and their transformation into pyridazines via inverse-electron demand Diels-Alder cycloaddition (IEDDA).

We report the synthesis of novel triphenylamine-tetrazine-tetracyanobutadiene based asymmetric and symmetric push-pull chromophores (1T and 1DT) by [2 + 2] cycloaddition-retroelectrocyclization of tetrazine connected electron-rich ethynyl triphenylamine with tetracyanoethene (TCNE). The electron-deficient tetrazine and tetracyanobutadiene (TCBD) moieties in 1T and 1DT create strong intramolecular charge transfer (ICT) interactions with TPA units, resulting in strong visible absorption with red edges reaching up to 700 nm (bandgaps of 1.79-1.89 eV). Furthermore, the structural, optical, and electronic properties of 1T and 1DT have been further tuned by transforming tetrazine units into pyridazines (1T-P and 1DT-P) via inverse-electron demand Diels-Alder cycloaddition (IEDDA). The relatively electron-donating character of pyridazine raised the HOMO and LUMO energies and widened the bandgap by ∼0.2 eV. This is the first synthetic strategy which allows two levels of tuning of the properties. 1DT acts as a selective colorimetric sensor for CN-via a nucleophilic attack on the dicyanovinyl unit of TCBD. The transformation results in a distinct colour change from orange to brown, while no change was observed for a range of anions tested (F-, Br-, HSO4-, NO3-, BF4-, and ClO4-).

Design, spectroscopic, structural characterization, and biological studies for new complexes via charge transfer interaction of ciprofloxacin drug with π acceptors

Ciprofloxacin (CIP) is a common antibiotic drug used as a strudy electron donor that interacts with dynamic π-acceptors such as 2,3-dinitrosalsylic acid (HDNS) and Tetracyanoethylene (TCNE) for synthesizing a new model of charge transfer (CT) complexes. The synthesized complexes were identified using diverse analytical methods such as UV–vis spectra, photometric titration measurements, FT-IR, 1H NMR Spectroscopy, and thermogravimetric analysis techniques (TGA/DTA). The stoichiometries for all the formed complexes were found to be 1:1 M ratio between the reactants. The characteristic spectroscopic properties such as transition dipole moment (μ), oscillator strength (ƒ), formation constant (KCT), ionization potential (ID), standard free energy (ΔG), and energy of interaction (ECT) for the CT-complexes were collected. The developed CT-complexes were tested for their toxicity on main organs, antimicrobial activity, antioxidant activity, and biofilm formation.

Reactivity of the TpRu(HN=CPh2)(PPh3)−Azido complex and Insertion of Methylene into the Tp B−H Bond

• We report [3+2] cycloaddition reactions of alkyne with the ruthenium azido complex. • The stable triazolato and tetrazolato products obtained in all cases were N (2)-bound. • We report that during protonation of ruthenium azido complex, methylene insertion accidentally took place, to yield unusual boron-methylated product. • Their structures are elucidated by IR, NMR and X-ray crystallography. Herein, we report on the reactivity of an Ru(II) azido complex allowing the facile synthesis of further interesting complexes. Starting from the parent chlorido complex (HN=CPh 2 )[Ru]−Cl { 1 , [Ru] = Tp(PPh 3 )Ru; Tp = HB(pz) 3 , pz = pyrazolyl)} the title complex (HN=CPh 2 )[Ru]−N 3 ( 2 ) was obtained upon reaction with NaN 3 . The N (2)-bound 4,5-bis-(methoxycarbonyl)-1,2,3-triazolato complex (HN=CPh 2 )[Ru]−{N 3 C 2 (CO 2 Me) 2 } ( 3 ) was obtained from reaction of 2 with dimethyl acetylene dicarboxylate (DMAD). Protonation of 3 with HCl afforded the N -coordinated triazolato complex {HN 3 C 2 (CO 2 Me) 2 }[Ru]−Cl ( 4 ). Reaction of CS 2 with 2 produced the thiocyanato complex (HN=CPh 2 )[Ru]−NCS ( 5 ). The Ru tetrazolato complex (HN=CPh 2 )[Ru]−N 4 C[C(CN)=C(CN) 2 ] ( 6 ) was prepared from 2 and tetracyanoethylene (TCNE). The reaction of 2 with HX gave the 17-electron Ru(III) complexes (Cl)[Ru]−X ( 7a , X = Cl ; 7b , X = Br) and the Ru(II) complexes containing the methyl tris(pyrazolyl)borate ligand Me Tp(PPh 3 )(HN=CPh 2 )Ru−X ( 8a , X = Cl ; 8b , X = Br), as a result of an unusual methylene insertion into the B−H bond of the Tp ligand with the CH 2 Cl 2 solvent as the assumed source for the methylene. The structures of 4, 5, 7a, 7b and 8b had been determined by X-ray diffraction analysis.

Electronic and Vibrational Manifold of Tetracyanoethylene-Chloronaphthalene Charge Transfer Complex in Solution: Insights from TD-DFT and Ab Initio Molecular Dynamics.

The interplay between light absorption and the molecular environment has a central role in the observed photophysics of a wide range of photoinduced chemical and biological phenomena. The understanding of the interplay between vibrational and electronic transitions is the focus of this work, since it can provide a rationale to tune the optical properties of charge transfer (CT) materials used for technological applications. A clear description of these processes poses a nontrivial challenge from both the theoretical and experimental points of view, where the main issue is how to accurately describe and probe drastic changes in the electronic structure and the ultrafast molecular relaxation and dynamics. In this work we focused on the intermolecular CT reaction that occurs upon photon absorption in a π-stacked model system in dichloromethane solution, in which the 1-chloronaphthalene (1ClN) acts as the electron donor and tetracyanoethylene (TCNE) is the electron acceptor. Density functional theory calculations have been carried out to characterize both the ground-state properties and more importantly the low-lying CT electronic transition, and excellent agreement with recently available experimental results [MathiesR. A.; et al. J. Phys. Chem. A2018, 122 ( (14), ), 359429558802] was obtained. The minima of the ground state and first singlet excited state have been accurately characterized in terms of spatial arrangements and vibrational Raman frequencies, and the CT natures of the first two low-lying electronic transitions in the absorption spectra have been addressed and clarified too. Finally, by modeling the possible coordination sites of the TCNE electron acceptor with respect to monovalent ions (Na+, K+) in an implicit solution of acetonitrile, we find that TCNE can accommodate a counterion in two different arrangements, parallel and orthogonal to the C=C axis, leading to the formation of a contact ion pair. The nature of the counterion and its relative position entail structural modifications of the TCNE radical anion, mainly the central C=C and C≡N bonds, compared to the isolated case. An important red shift of the C=C stretching frequency was observed when the counterion is orthogonal to the double bond, to a greater extent for Na+. On the contrary, in the second case, where the counterion ion lies along the internuclear C=C axis, we find that K+ polarizes the electron density of the double bond more, resulting in a greater red shift than with Na+.

Tuning electronic behaviors of WS2 by molecular doping

WS2 has become a hot research topic because of its excellent properties in the fields of chemistry, physics, and material science. We investigate the structural and electronic behaviors of organic molecules adsorbed on the WS2 single-layer using density functional theory. The results observed that organic molecules can inject additional carriers into the WS2 single-layer. Tetracyanoethylene (TCNE) and tetracyanoquinodimethane (TCNQ) doping achieve p-type doping, while tetrathiafulvalene (TTF) doping can introduce n-type doping behavior. Furthermore, the work function of WS2 can be tuned in the range of 4.05 eV to 5.71 eV after organic molecules doping. Importantly, the doping gap of the TTF-WS2 systems is reduced with the decrease of the applied negative electric field. Especially at − 0.45 V/Å, the doping gap of the TTF-WS2 system is 0.01 eV. It demonstrated that the applied negative electric field can induce effective n-type doping behavior. Therefore, organic molecular doping can regular the electronic behaviors of WS2, which is useful for the design of nanoelectronic devices.

Catalytic and Multicomponent Reactions for Green Synthesis of Some Pyrazolone Compounds and Evaluation as Antimicrobial Agents.

A green synthetic approach and facile method was developed to produce pyrazole compounds (6a–d) by the reaction of ethyl acetoacetate (1), hydrazines (2a–d), and catalytic imidazole (3) in aqueous media. 4-Dicyanomethylene-2-pyrazoline-5-one derivatives (14a–d) were synthesized through the reaction of 2-pyrazoline-5-one derivatives (6a–d) with tetracyanoethylene (TCE) (7) by using catalytic imidazole (3) in an aqueous medium. Moreover, the 4-dicyanomethylene derivative (16) was obtained via treatment of 1-phenyl-3,5-pyrazolidinedione (15) with TCE (7). The spiropyrazoleoxirane derivatives (18 and 20) were prepared by treating the precursor 4-dicyanomethylene-2-pyrazoline-5-one derivative (14b) with hydrogen peroxide in various polar solvents under alkaline conditions. The spiropyrazole oxirane derivative (18) was used as a precursor for the design of functionalized pyrazolone derivatives (24 and 27a, b). The chemical structure of the novel designed derivatives was ascertained based on elemental analyses, mp, thin-layer chromatography, and spectral analyses. Furthermore, some of the synthesized derivatives were examined against different pathogenic bacterial and fungal strains. Their results demonstrated that some of them revealed notable antimicrobial activities.

Do Antarafacial Cycloadditions Occur? Cycloaddition of Heptafulvalene with Tetracyanoethylene.

The cycloaddition of heptafulvalene (1) with tetracyanoethylene (TCNE) was previously described as an example of an antarafacial cycloaddition, a [π14 a +π2 s ] process that afforded only the trans cycloadduct by virtue of the edge-to-face approach of TCNE, facilitated by the S shape of 1. The reaction has been investigated in depth and found not to be a concerted antarafacial process. At low temperature, the reaction is observed to give a mixture of cis and trans cycloadducts as well as a [4+2] cycloadduct. The mixture of products is converted to the trans cycloadduct by equilibration upon warming to room temperature. Studies with diethyl 2,3-dicyanofumarate and -maleate confirmed the formation of cis cycloadducts. DFT studies at the M06-2X/6-311+G(2d,p) SCRF=acetone level of theory show that the originally proposed edge-to-face approach of TCNE to 1 is highly disfavored, whereas a stepwise mechanism involving the addition of TCNE at C2 to form a zwitterion followed by collapse at either C2' or C7' is energetically accessible. The Diels-Alder adduct is also formed in a stepwise reaction by competitive addition of TCNE at C4 of 1. These studies suggest that edge-to-face interactions are prohibitive in even the most favorable cases.

The Electronic Properties of g−ZnO Modulated by Organic Molecules Adsorption

Molecular doping is an excellent instrument to modify the electronic properties of two−dimensional materials. In our work, the structure and electronic properties of the adsorption systems of g−ZnO adsorbed by organic molecules (including Tetracyanoethylene (TCNE), Tetracyanoquinodimethane (TCNQ), and Tetrahydrofulvalene (TTF)) were investigated computationally using Density Functional Theory (DFT). The results showed that the TCNE and TCNQ, as electron receptors, doped the LUMO energy level above the valence band maximum (VBM) of the g−ZnO band structure, demonstrating effective p−type doping. The n−type doping of g−ZnO was obtained that the TTF molecules, as electron donors, doped the HOMO energy level below the conduction band minimum (CBM) of the band structure for g−ZnO. In addition, the TCNE, TCNQ, and TTF breathed additional holes or electrons into the monolayer g−ZnO, creating surface dipole moments between the g−ZnO and organic molecules, which caused work function to be adjustable, ranging from 3.871 eV to 5.260 eV. Our results prove that organic molecular doping was instrumental in improving the performance of g−ZnO−based nano−electronic devices, providing theoretical support for the fabrication of p−doping or n−doping nano−semiconductor components. The tunable range of field emission capability of g−ZnO−based electronic devices was also extended.

Near‐IR Intramolecular Charge Transfer in Strongly Interacting Diphenothiazene‐TCBD and Diphenothiazene‐DCNQ Push‐Pull Triads

AbstractThree types of phenothiazines dimers (PTZ‐PTZ, 1–3), covalently linked with one or two acetylene linkers, were synthesized by copper‐mediated Eglinton and Pd‐catalyzed Sonogashira coupling reactions in excellent yields. The dimers 1–3 were further engaged in [2+2] cycloaddition‐retroelectrocyclization reactions with strong electron acceptors, tetracyanoethylene (TCNE) and 7,7,8,8‐tetracyanoquinodimethane (TCNQ) to yield tetracyanobutadiene (TCBD, 1 a–3 a), and dicyanoquinodimethane (DCNQ, 1 b–3 b) functionalized donor‐acceptor (D‐A) conjugates, respectively. The conjugates were examined by a series of spectral, computational, and electrochemical studies. Strong ground state polarization leading to new optical transitions was witnessed in both series of D‐A conjugates. In the case of DCNQ derived D‐A system 1 b, the optical coverage extended until 1200 nm in benzonitrile, making this a rare class of D‐A ICT system. Multiple redox processes were witnessed in these D‐A systems, and the frontier orbitals generated on DFT optimized structures further supported the ICT phenomenon. Photochemical studies performed using femtosecond pump‐probe studies confirmed solvent polarity dependent excited state charge transfer and separation in these novel multi‐modular D‐A conjugates. The charge‐separated states lasted up to 70 ps in benzonitrile while in toluene slightly prolonged lifetime of up to 100 ps was witnessed. The significance of phenothiazine dimer in wide‐band optical capture all the way into the near‐IR region and promoting ultrafast photoinduced charge transfer in the D‐A‐D configured multi‐modular systems, and the effect of donor‐acceptor distance and the solvent polarity was the direct outcome of the present study.

Intermolecular interactions of tetracyanoethylene (TCNE) and fumaronitrile (FN) with minor amines: A combined UV-Vis and EPR study.

In this paper, the nature of interactions between two cyanocarbons-tetracyanoethylene (TCNE) and fumaronitrile (FN)-and a series of four secondary amines possessing a general formula C4HxN (x = 5-11) is thoroughly scrutinized. For all of the TCNE-amine pairs, tricyanovinylation (TCV) reaction is observed; however, only for pyrrole, it is accompanied with a visible charge-transfer (CT) complex formation-no such chemical individuals, characteristic for TCNE, have been noticed for aliphatic and alicyclic amines. On the contrary, FN forms such complexes with all the amines studied. Interestingly, a rather unexpected reaction of FN with alicyclic amines has been observed. The recorded electron paramagnetic resonance (EPR) spectra indicate the presence of both TCNE●- and FN●- radicals in the analyzed samples, assigned to a complete charge (electron) transfer process within the CT complexes, whose efficiency can be additionally enhanced by photoirradiation. The origination of the former radical, whose presence is observed also in the TCNE-diethylamine mixture, is as well proposed to result indirectly from the TCV reaction, occurring for this system. Finally, the superhyperfine structure of EPR spectra, indicating the existence of some secondary interactions of the radicals with surrounding compounds, is discussed. Formation of CT complexes and tricyanovinylates has been investigated and characterized with UV-Vis spectroscopy, while the presence of (cyano)radicals in the analyzed mixtures has been evidenced by (photoinduced) EPR measurements. Interpretation of the experimental results is also supplemented with computer simulations including density functional theory calculations.

Enhancing the Antipsychotic Effect of Risperidone by Increasing Its Binding Affinity to Serotonin Receptor via Picric Acid: A Molecular Dynamics Simulation.

The aim of this study was to assess the utility of inexpensive techniques in evaluating the interactions of risperidone (Ris) with different traditional π-acceptors, with subsequent application of the findings into a Ris pharmaceutical formulation with improved therapeutic properties. Molecular docking calculations were performed using Ris and its different charge-transfer complexes (CT) with picric acid (PA), 2,3-dichloro-5,6-dicyanop-benzoquinon (DDQ), tetracyanoquinodimethane (TCNQ), tetracyano ethylene (TCNE), tetrabromo-pquinon (BL), and tetrachloro-p-quinon (CL), as donors, and three receptors (serotonin, dopamine, and adrenergic) as acceptors to study the comparative interactions among them. To refine the docking results and further investigate the molecular processes of receptor–ligand interactions, a molecular dynamics simulation was run with output obtained from AutoDock Vina. Among all investigated complexes, the [(Ris) (PA)]-serotonin (CTcS) complex showed the highest binding energy. Molecular dynamics simulation of the 100 ns run revealed that both the Ris-serotonin (RisS) and CTcS complexes had a stable conformation; however, the CTcS complex was more stable.

2+2] Cycloaddition-retroelectrocyclization reactivity and thin film transistor performances of carbazole-based platinum polyyne polymers

Carbazole-based platinum polyyne polymers are a good platform for the postfunctional formation of donor-acceptor type narrow band gap polymers by the [2 + 2] cycloaddition-retroelectrocyclization reaction with tetracyanoethylene (TCNE). The TCNE reactivity depends on the connectivity pattern of the carbazole. The 3,6-cabazole-based polymer shows a higher reactivity than the corresponding 2,7-carbazole-based polymer due to the p-positions with respect to the sp3 nitrogen atom. The connectivity pattern leads to the regioregularity difference in the resulting polymers. When TCNE is added to one of the alkynes of the 3,6-diethynylcarbazole unit, the electron-donating nature of the carbazole is lowered and the second TCNE addition does not occur. Accordingly, the regioregular polymer is formed from the 3,6-carbazole-based polymer, which is revealed from the 1H NMR spectrum. In contrast, the TCNE addition of the 2,7-carbazole-based polymer is mainly governed by the platinum atom, which produces a regiorandom structure. Finally, the charge carrier transporting properties of the precursor polymers are evaluated in thin film transistors. The 3,6-carbazole-based polymer displays a one order higher hole mobility than the corresponding 2,7-carbazole-based polymer. This result suggests that the shallower HOMO level of the former polymer facilitates the hole injection.

Donor‐Acceptor Based 1,8‐Naphthalimide Substituted Phenothiazines: Tuning of HOMO‐LUMO Gap

AbstractA set of donor‐acceptor (D‐A) substituted phenothiazine based chromophores (D‐π‐D‐π‐A, D′‐π‐D‐π‐A, D‐A′‐D‐π‐A and D′‐A′‐D‐π‐A) were designed and synthesized. The phenothiazine was substituted with the 4‐ethynyl‐1,8‐naphthalimide (NPI) on one side and a variety of donors (phenothiazine, carbazole, ferrocene and triphenylamine) were introduced on the other side of phenothiazine via Pd‐catalyzed Sonogashira cross‐coupling reaction resulting PTZ8–11. In order to tune the optoelectronic properties of the phenothiazine chromophores, cyano‐based acceptor 1,1,4,4‐tetracyanobuta‐1,3‐diene (TCBD) was incorporated by [2+2] cycloaddition‐electrocyclic ring‐opening reaction of phenothiazine derivatives PTZs 8–11 and tetracyanoethylene (TCNE). The photophysical and electrochemical studies showed that the incorporation of TCBD acceptor in the phenothiazine chromophores PTZs 12–15 facilitated the donor‐acceptor strength to greater extent. The electronic absorption spectra exhibited red shifted absorption bands for the TCBD substituted phenothiazines as compared to the alkynylated phenothiazines which led to much lower optical band gaps in the formers. The experimental values were also supported by the DFT and TD‐DFT calculations.

β-Tetracyanobutadiene-Appended Porphyrins: Facile Synthesis, Spectral and Electrochemical Redox Properties, and Their Utilization as Excellent Optical Limiters.

A series of β-TCBD (1,1,4,4-tetracyano-buta-1,3-diene)-appended porphyrins, M-TCBD (M = 2H, Co(II), Ni(II), Cu(II), and Zn(II)), was synthesized from 2,3-diphenylethynyl-12-nitro-meso-tetraphenylporphyrin, H2-PE2, and characterized by various spectroscopic techniques and electrochemical studies. The reaction proceeds via [2 + 2] cycloaddition and retroelectrocyclization reactions of tetracyanoethylene (TCNE) with H2-PE2. The observed unusual reduction potentials in the cyclic voltammograms of the synthesized porphyrins in the range of -0.06 to -0.10 V are the consequence of the TCBD moiety present at the β-position of the porphyrin macrocycle. Notably, these porphyrins exhibited three porphyrin ring-centered reductions due to extended π-conjugation. The higher nonlinear optical response exhibited by the M-TCBD series as compared to the precursor (H2-PE2) was attributed to the existence of intramolecular charge transfer and enhanced polarization in the M-TCBD series. The single-beam femtosecond Z-scan measurements were performed to elucidate the third-order nonlinear optical properties, and the temporal response of these porphyrin molecules was investigated using optical pump-probe spectroscopy to study the excited state absorption dynamics. Z-scan measurements revealed that Co-TCBD exhibited a higher nonlinear optical response as compared to free base porphyrins. The two-photon absorption coefficient (β) and the imaginary part of third-order nonlinear optical susceptibility (χ(3)) were obtained from the open aperture experiment, whereas the close aperture experiment delivered the magnitude and the sign of the nonlinear refractive index (n2) and the real part of χ(3). Furthermore, the femtosecond transient absorption spectroscopy revealed a faster relaxation dynamics of various absorption processes in a picosecond timescale. The excellent optical limiting threshold (1.90-2.33 × 1015 W/m2) of the synthesized porphyrins makes them good materials for laser protection and high-power laser operation.

Study on electronic properties and charge transfer doping of organic molecules adsorbed g-GaN monolayer

Two-dimensional GaN has attracted much attention owing to its excellent electronic and photoelectric properties. Tuning charge transfer and electronic characteristics of g-GaN are essential to its applications in electronic and optoelectronic devices. In this work, the electronic structures and charge transfer of organic molecules adsorbed g-GaN systems tetracyanoethylene (TCNE)/g-GaN, tetracyanoquinodimethane (TCNQ)/g-GaN, and tetrathiafulvalene (TTF)/g-GaN are explored based on first-principles. The results show that the TCNE and TCNQ molecules inject additional holes into g-GaN monolayer, and p-type doping is achieved in g-GaN monolayer. While a deep impurity level is introduced to TTF/g-GaN doping system, and the TTF injects minute quantities of additional electrons into g-GaN monolayer. The charge transfer and electronic characteristics of TCNE/g-GaN, TCNQ/g-GaN, and TTF/g-GaN doping systems are sensitive to applied vertical electric field. Our work has great potential for g-GaN application in nano electronic and photoelectric devices.

Synthesis, spectroscopic and thermodynamic study of charge transfer complexes of natural drug rutin as donor with Π-acceptors; 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and tetracyanoethylene

Molecular charge-transfer complexes of the donor rutin with π-acceptors tetracyanoethylene (TCNE) and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) were studied spectrophotometrically in two different solvents (methanol and ethanol) at three temperatures, 15, 20 and 25 °C . Formed complexes exhibit well resolved charge-transfer bands in the regions where neither donor nor acceptors have any absorption. the composition of the CTC were determined using molar ratio method and Benesi-Hildbrand equation was used to calculate the formation constants KCT and the molar extinction coefficient ɛCT of the formed CT complexes. Solid CTC were characterized by FT-IR and NMR spectroscopy. CT complexes formed in the reaction of rutin and π-acceptors DDQ and TCNE have high formation constants KCT indicating the high stability of these complexes. The latter was found to be influenced by the solvent nature, indeed, KCT values of [rut-DDQ] complex formed in ethanol are higher than those of the same complex formed in methanol, but KCT values of [rut-TCNE] complex formed in methanol are higher than those of the same complex formed in ethanol. Our results suggest the formation of stable CT complexes of rutin with π-acceptors (DDQ and TCNE).

Toward Targeted Kinetic Trapping of Organic-Inorganic Interfaces: A Computational Case Study.

Properties of inorganic–organic interfaces, such as their interface dipole, strongly depend on the structural arrangements of the organic molecules. A prime example is tetracyanoethylene (TCNE) on Cu(111), which shows two different phases with significantly different work functions. However, the thermodynamically preferred phase is not always the one that is best suited for a given application. Rather, it may be desirable to selectively grow a kinetically trapped structure. In this work, we employ density functional theory and transition state theory to discuss under which conditions such a kinetic trapping might be possible for the model system of TCNE on Cu. Specifically, we want to trap the molecules in the first layer in a flat-lying orientation. This requires temperatures that are sufficiently low to suppress the reorientation of the molecules, which is thermodynamically more favorable for high dosages, but still high enough to enable ordered growth through diffusion of molecules. On the basis of the temperature-dependent diffusion and reorientation rates, we propose a temperature range at which the reorientation can be successfully suppressed.