Addition Of Tetracyanoethylene Research Articles

Impact of tetracyanoethylene plasticizer on PEO based solid polymer electrolytes for improved ionic conductivity and solid-state lithium-ion battery performance

Poly(ethylene oxide) is a promising material for solid-state lithium batteries due to its safety, ease of processing, and compatibility with lithium. However, conventional linear PEO falls short of practical requirements due to its limited ionic conductivity, a consequence of the high crystallinity of its ethylene oxide chains. This crystallinity hinders the movement of lithium ions, limiting its performance in solid-state battery applications. In this study, we successfully prepared the plasticized solid polymer electrolytes (PSPEs) based on poly(ethylene oxide) (PEO)/tetracyanoethylene (TCE) complexed with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt and studied the effect of TCE on structural, mechanical, electrical and electrochemical properties of PSPEs. The addition of tetracyanoethylene effectively disrupts the crystallinity of the PEO matrix, as confirmed by X-ray diffraction analysis. The addition of TCE also enhanced the elongation-at-break of the PEO12-LiTFSI system, indicating improved flexibility. Consequently, the ionic conductivity of the SPEs increases with increasing tetracyanoethylene content, reaching a maximum of 1.14 × 10−4 S/cm at 25 °C for the electrolyte containing 30 wt% of tetracyanoethylene. Furthermore, the plasticized SPEs exhibit a wide electrochemical stability window, as determined by linear sweep voltammetry. Solid-state battery tests demonstrate a high initial discharge capacity of 143.5 mAhg−1 at 0.1C along with good cycling performance.

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.

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.

Study on the Synthesis of Charge Transfer Complex of Nifedipine and Tetracyanoethylene

Purposes: To construct a new method for the determination of nifedipine and apply it to the determination of in vitro drugs in order to achieve simple and accurate quantitative detection. Procedures: A charge transfer complex of nifedipine tetracyanoethylene was constructed, and the fluorescence intensity changes of the complex and nifedipine were compared. Screen the effect of drug dosage, reaction time and reaction temperature on the fluorescence intensity of the system. Results: Nifedipine is a substance with its own fluorescence characteristics, but its own fluorescence intensity is not as high as expected. Through the addition of tetracyanoethylene, it is found that the fluorescence intensity of nifedipine has been greatly enhanced, combined with ultraviolet A new absorption peak was found in the spectrum, indicating that the two were successfully complexed. Conclusions: The experiment successfully synthesized the nifedipine charge transfer complex, and constructed a new method for the determination of nifedipine content, which is of great significance for the determination of the content of drugs in vitro.

New insights into the electrophilic aromatic substitution mechanism of tricyanovinylation reaction involving tetracyanoethylene and N,N-dimethylaniline: An interpretation based on density functional theory calculations

The reaction between tetracyanoethylene and N,N-dimethylaniline was extensively studied in early of 1960's. Surprisingly, the role of intermediate species involved in the reaction mechanism is still ambiguous. New density functional theory (DFT) calculations have been performed in order to elucidate such reaction pathways. The electrophilic addition of tetracyanoethylene was computed with a free energy barrier of 79 kJ mol−1. The rate-determining step (RDS) of the reaction was observed during the base-assisted deprotonation process, with a calculated value of 103 kJ mol−1. Finally, for the elimination reaction step was obtained a value at 70 kJ mol−1. A strong influence of the solvent polarity has been corroborating the presence of a polar transition state for the RDS of this reaction. Nonpolar solvent provides a higher relative free energy barrier, which is in agreement with experimental observations.

An N‐Heterocyclic‐Carbene–Tetracyanoethylene Zwitterion: Experimental and Theoretical Study on Its Formation and Reactivity

The direct addition of tetracyanoethylene (TCNE) to the carbene center of 1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene (IPr) was successfully demonstrated. The IPr–TCNE adduct, that is, zwitterion 1, clearly differs from the typical [2+1]‐cycloaddition products obtained from the reaction of carbenes with olefins. The results obtained from experimental and theoretical studies suggest that adduct 1 disassembles into IPr and TCNE, which is followed by the addition of IPr to the nitrile carbon atom of TCNE and subsequent isomerization into a thermodynamically more stable singlet nitrene intermediate. This intermediate is then captured by an additional molecule of TCNE to afford another heterocycle. This study reveals a unique example of the reactivity between N‐heterocyclic carbenes and olefins.

Reactions of Alkynyl‐ and 1,1′‐Dialkynylferrocenes with Tetracyanoethylene – Unanticipated Addition at the Less Electron‐Rich of Two Triple Bonds

AbstractAlkynylferrocenes react with tetracyanoethylene (TCNE) to form 2‐ferrocenyl‐1,1,4,4‐tetracyanobutadienes. These reactions occur under mild reaction conditions in almost quantitative yields if the triple bond is electron‐rich. Systems with more than one triple bond, namely, 1,1′‐dialkynylferrocenes or diynylferrocenes, react once at the more electron‐rich triple bond, and the second reaction cannot be achieved, even under more‐forcing reaction conditions. For a diyne with the reactivity switched by oxidation of the ferrocenyl moiety to the corresponding ferrocenium salt, the addition of TCNE occurred at the less electron‐rich triple bond. This unprecedented reactivity is explained by the resonance stabilization of a diradical intermediate. A push–pull 1,1′‐dialkynylferrocene with a [4‐(dimethylamino)phenyl]ethynyl and a (4‐nitrophenyl)ethynyl substituent reacted exclusively at the [4‐(dimethylamino)phenyl]ethynyl triple bond.

Tuning optical and electronic properties of poly(4,4'-triphenylamine vinylene)s by post-modification reactions

New triphenylamine-based polyarylenevinylenes with pendant phenylethynyl- and 3-pyridylethynyl substituents were synthesized by Stille polycondensation of trans-1,2-bis(tributylstannyl)ethene with two new ethynyl substituted triphenylamine monomers, i.e., N,N-bis(4-iodophenyl)-4'-(phenylethynyl) phenylamine and N,N-bis(4-iodophenyl)-4'-(3-pyridylethynyl) phenylamine. The polymers were characterized by spectral methods and cyclic voltammetry and their properties were compared with those of the unsubstituted poly(4,4'-triphenylamine vinylene). Chemical post-modifications of the polymers by tetracyanoethylene addition to the triple bond, and quaternization of pyridyl group with accent on the fine-tuning of the optical and electrochemical properties were also studied. Density functional theory calculations provide a reliable interpretation of the observed spectra and electrochemical data.

Attempted Inversion of Semiconducting Features of Platinum Polyyne Polymers: A New Approach for All‐Polymer Solar Cells

AbstractPlatinum(II) polyyne polymers containing thiophene‐acceptor‐thiophene units are synthesized, and their main chain alkynes are functionalized by the formal cycloaddition–retro‐electrocyclization reaction with tetracyanoethylene (TCNE). The polymer energy levels are significantly decreased by the TCNE addition. Bulk‐heterojunction solar cells are fabricated using the TCNE‐adducted platinum(II) polyyne polymers. The use of these polymers as p‐type semiconductors in combination with n‐type fullerene derivatives indicates that the p‐type semiconducting ability decreases by approximately five to ten times after the TCNE addition. On the contrary, when the TCNE‐adducted polymers are employed as a substitute for the fullerene derivatives, the all‐polymer solar cells are initially fabricated.magnified image

Effects of click postfunctionalization on thermal stability and field effect transistor performances of aromatic polyamines

Tetracyanoethylene (TCNE) was stepwise added to the side chain alkynes of aromatic polyamines undergoing a click chemistry-type addition reaction via a [2 + 2] cycloaddition followed by a cycloreversion process. The quantitative addition was confirmed by the comprehensive spectroscopic analyses of the full TCNE adducts. An X-ray crystallographic analysis revealed the polymerization incapability of the TCNE-adducted aromatic amine monomers due to the decreased basicity of the amino group. This fact indicated that the click postfunctionalization is an alternative and useful method for obtaining the desired polymers. The efficient intramolecular donor–acceptor interactions were elucidated from the appearance of the charge-transfer bands as well as the fluorescence quenching. When the dimethylamino donors are positioned at the polymer side chains, the appropriate donor–acceptor balance is achieved, resulting in the enhancement of the thermal properties. Thus, as more TCNEs were added, both the decomposition and glass transition temperatures of the aromatic polyamine gradually increased. A careful analysis of the differential pulse voltammogram (DPV) curves also revealed the gradual cathodic shifts in both the oxidation and reduction potentials with the TCNE addition amount. This result suggested that the polymer energy levels, namely the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels, can be lowered by the added TCNE amount. Their thin film transistors were fabricated, and a clear correlation between the polymer energy levels and hole mobilities was demonstrated.

One‐step synthesis of ladder‐type fused poly(benzopentalene) derivatives with tunable energy levels by variable substituents

AbstractNovel ladder‐type conjugated polymers, fused poly (benzopentalene) derivatives, were synthesized from the readily accessible 1,4‐dibromo‐2,5‐diethynylbenzene derivatives by the Pd‐catalyzed self‐polycondensation in one‐step with high yields. The low solubility of the ladder structure was suggested when the triisopropylsilyl substituents were selected. However, when longer alkyl chains were introduced into the peripheral moieties, such as the dialkylanilino (DAA) and alkyloxyphenyl groups, a high solubility was achieved and the number‐average molecular weight (Mn) reached 18,000. The UV‐Vis absorption spectral shapes of the polymers were similar to the reported dibenzopentalene derivatives, except for the bathochromically shifted end absorptions. This result suggests an extension of the π‐conjugated systems due to the polymerization. Moreover, the almost defect‐free structure of the ladder‐type polymers was confirmed by the quantitative tetracyanoethylene (TCNE) addition to the DAA‐activated alkynes. The titration experiments of TCNE to the polymers revealed the number of terminal alkynes, which enabled us to calculate the molecular weight of the polymers. The calculated molecular weight was consistent with that determined by GPC. After the TCNE addition, the polymer band gaps reasonably decreased as suggested by the UV‐Vis‐NIR absorption and electrochemical measurements. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

ChemInform Abstract: Synthesis of Diethylammonium 3,4‐Dicyano‐5,6,7,8‐tetrahydroquinolin‐2‐olates.

4-Oxoalkane-1,1,2,2-tetracarbonitriles are products of addition of tetracyanoethylene to ketones. Their molecules possess several electrophilic centers capable of reacting with nucleophiles. However, studies on reactions of these compounds with nitrogen-centered nucleophiles are very few in number. It was reported that reactions of 4-oxoalkane-1,1,2,2-tetracarbonitriles with aqueous ammonia lead to formation of isonicotinic acid derivatives [1] and 2,7-diazabicyclo[3.2.1]oct-3-enes [2].

Synthesis of diethylammonium 3,4-dicyano-5,6,7,8-tetrahydroquinolin-2-olates

4-Oxoalkane-1,1,2,2-tetracarbonitriles are products of addition of tetracyanoethylene to ketones. Their molecules possess several electrophilic centers capable of reacting with nucleophiles. However, studies on reactions of these compounds with nitrogen-centered nucleophiles are very few in number. It was reported that reactions of 4-oxoalkane-1,1,2,2-tetracarbonitriles with aqueous ammonia lead to formation of isonicotinic acid derivatives [1] and 2,7-diazabicyclo[3.2.1]oct-3-enes [2].

Click-Type Reaction of Aromatic Polyamines for Improvement of Thermal and Optoelectronic Properties

A quantitative addition reaction between aromatic amino-substituted alkynes and tetracyanoethylene (TCNE), yielding donor-substituted tetracyanobutadiene chromophores, was for the first time employed as a click-type reaction to improve the thermal and optoelectronic properties of aromatic polyamines. The first reduction potentials or the LUMO levels of the aromatic polyamines were found to linearly decrease by the stepwise TCNE addition.

Reduced Band Gap Dithieno[3,2-b:2‘,3‘-d]pyrroles: New n-Type Organic Materials via Unexpected Reactivity

Direct addition of tetracyanoethylene to N-(p-hexylphenyl)dithieno[3,2-b:2',3'-d]pyrrole yields not only the aromatic mono- and bis-tricyanovinyl-substituted products but also a quinoidal product with dicyanomethylene groups. The analogous reaction with dithieno[3,2-b:2',3'-d]thiophene yields exclusively the aromatic mono-tricyanovinyl product. The aromatic and quinoidal products possess red-shifted absorptions, increased electron affinities, and favorable pi-stacking motifs in comparison to the unsubstituted oligomers.

A Re-Evaluation of the Electrophilic Substitution Reactions of the Ramirez Ylide

Cyclopentadienylidenetriphenylphosphorane (the Ramirez ylide), unexpectedly and contrary to a number of earlier reports, has been shown to be like pyrrole in undergoing electrophilic substitution on the cyclopentadienide ring at either the 3- or the 2-position, depending on the electrophile. Formylation under Vilsmeier conditions and addition of tetracyanoethylene occurs at the 3-position, while activated acetylenes and the nitrosyl electrophile substitute at the 2 position. The 3-formylated product was reduced to the 3-methyl derivative and it also reacted under Knoevenagel conditions to give a number of novel condensation products. The results of single-crystal X-ray crystallographic analyses are given for four of the compounds studied, and a careful 2D NMR analysis of all of the compounds was performed in order to develop a reliable method for the unambiguous assignment of the regiochemistry of adduct formation.

Single molecule force spectroscopy of smart poly(ferrocenylsilane) macromolecules: Towards highly controlled redox-driven single chain motors

We investigated various stimuli-responsive poly(ferrocenylsilane) (PFS) polymers as model systems for the realization of molecular motors powered by a redox process. Covalently end-grafted PFS on gold, as well as PFS homopolymers and block copolymers in ultrathin films, were studied by AFM-based single molecule force spectroscopy (SMFS). Surface confined PFS macromolecules were chemically oxidized by addition of tetracyanoethylene or were completely and reversibly oxidized (and reduced) in situ by applying an electrochemical potential. Chemical oxidation was successful only for the block copolymers. The entropic elasticity of neutral PFS chains (Kuhn length IK∼0.40nm) was found to be larger than that of oxidized PFS chains (IK∼0.65nm) in the lower force regime. The elasticities could be reversibly controlled in situ by adjusting the applied potential in electrochemical SMFS experiments. For a single PFS macromolecule (DP=80) operating cycle, a work output and an efficiency of 3.4×10−19J and ∼5%, respectively, were estimated based on the single chain experimental data.

Reactions of cobaloxime η 1-allyl complexes with electron deficient alkenes

The preparation of several new η 1-allyl (dimethylglyoxime) 2 cobalt complexes ( 7– 12) containing varied axial pyridine ligands is reported. These complexes are synthesized via three different methods: (1) in situ generation and allylation of [L(dmg) 2Co] 2 dimers (where L=various pyridines); (2) generation and allylation of L(dmg) 2Co anions; and (3) an apparent 1,4-hydrocobaltation of 1,3-dienes. Tetracyanoethylene addition to cobaloxime allyl complexes ( 5– 12) yielded cyclized complexes ( 17– 23) and insertion products ( 24– 27). Yields of the cyclized and uncyclized complexes are influenced by the electronics of the axial pyridine ligand with the more electron withdrawing pyridine ligands favoring the formation of more cyclized product. Treatment of cobaloxime allyl complexes ( 8– 10) with benzoquinone yielded rearranged cobaloxime allyl complexes ( 30 and 31) along with para-allyloxysubstituted phenols ( 32– 34). The substituted phenols presumably arise from a Michael addition of the allyl fragment onto benzoquinone followed by a retro Claisen reaction.

Binary Solvent Extractions of Upper Freeport Coal

Different organic bases, primarily with carbon disulfide as co-solvent, were used to probe the nature of the binary solvent extractions of Upper Freeport coal. The effect of tetracyanoethylene addition on extract yields was also examined. Amides and cyclic ureas where found to all be good extractants, but were not as efficient as N-methylpyrrolidone(I), with one exception. CS2/N-methylpyridone was found to be a better solvent than CS2/(I). The results suggest that solvents which have similar basicities, but have a more flattened shape, such as aromatic rings compared to saturated rings, are better extraction agents.

Increase of the extraction yields of coals by the addition of aromatic amines

The effect of the addition of aromatic amines on the yields of the extraction of Argonne Premium coals with carbon disulfide– N-methyl-2-pyrrolidinone (CS 2–NMP) mixed solvent (1:1 by volume) was investigated. The addition of a very small amount (25 mg/g-coal) of p-phenylenediamine ( p-PDA) increased the extraction yield of Upper Freeport (UF) coal from 51.4 to 81.3%. The solvent fractionation of the extracts obtained shows that the increase in the yield was caused mainly by the increase of the heaviest fraction, i.e. pyridine insoluble fraction (PI), and not that of the lighter pyridine soluble fraction. p-PDA was also found to increase the solubility of PI in the CS 2–NMP mixed solvent. These behaviors of p-PDA are very similar to those already observed by the addition of tetracyanoethylene, and can be explained by the breaking of the associates among coal molecules through the interaction of the amines with coal. The extraction yields of other Argonne Premium coals than UF coal also increased their extraction yields, but only slightly. The results obtained from the addition of various aromatic amines with different structure and electron donatability suggest that the hydrogen bonds, not electron donor–acceptor interaction, of the amines with coal seem to be responsible for the solubility enhancements of the coals and extracts. Effect of water on the extraction yield was also examined.