Cyanoacetic Acid Research Articles

Photoelectrochemical properties and interfacial charge transfer kinetics of BODIPY-sensitized TiO2 electrodes

We present studies of the photoelectrochemical characteristics and interfacial charge transfer dynamics of two (4,4′-difluoro-4-bora-3a,4a-diaza-s-indacene) BODIPY dyes (BODIPY-1 and 2) attached to nanostructured TiO2 electrodes. BODIPY-1 bears two carboxylic acid groups at its 2 and 6 positions and BODIPY-2 is modified with two cyanoacetic acid groups at these positions. Photoelectrochemistry measurements show that BODIPY-2 has better photostability and device short-circuit current density than BODIPY-1 because of its broader light absorption and efficient charge injection as shown by ultrafast transient absorption spectroscopy and steady-state photoelectrochemical studies. The more efficient photocurrent generation by BODIPY-2 is also attributed to the improved redox reaction kinetics with its hole transport media, I−/I3−, in comparison with BODIPY-1.

Synthesis, characterization, biological evaluation and in silico screening of oxadiazinanones

A series of novel oxadiazinan-5-one namely 2-methyl-2-phenyl-1,3,4-oxadiazinan-5-one (6), 2-(3-hydroxyphenyl)-2-methyl-1,3,4-oxadiazinan-5-one (7), 2-(4-hydroxyphenyl)-2-methyl-1,3,4-oxadiazinan-5-one (8), 2-(2,4-dihydroxyphenyl)-2-methyl-1,3,4-oxadiazinan-5-one (9) and 2-(2,5-dihydroxyphenyl)-2-methyl-1,3,4-oxadiazinan-5-one (10) have been synthesized by the reaction of acetophenone and its derivatives with cyanoacetic acid hydrazide. The structural assignments of the products were done on the basis of IR, 1H NMR, 13C NMR, MS, and analytical data. The in vitro antioxidant and antimicrobial activity of all the synthesized compounds (6–10) was tested by the DPPH and disk diffusion method, respectively. The synthesized compounds were screened against Gram-positive and Gram-negative bacterial and fungal strains. Compound (7) showed the highest inhibition comparable with the standard antibiotic drugs Ciprofloxacin and Amphotericin B. The antibacterial activity of the synthesized compounds was further investigated with the help of in silico docking study using Discovery studio 3.1, Molego Virtual Docker and LigandScout to predict the active sites.

Dye‐Sensitized Solar Cells Based on a Donor–Acceptor System with a Pyridine Cation as an Electron‐Withdrawing Anchoring Group

New hemicyanine dyes (CM101, CM102, CM103, and CM104) in which tetrahydroquinoline derivatives are used as electron donors and N-(carboxymethyl)-pyridinium is used as an electron acceptor and anchoring group were designed and synthesized for dye-sensitized solar cells (DSSCs). Compared with corresponding dyes that have cyanoacetic acid as the acceptor, N-(carboxymethyl)-pyridinium has a stronger electron-withdrawing ability, which causes the absorption maximum of dyes to be redshifted. The photovoltaic performance of the DSSCs based on dyes CM101-CM104 markedly depends on the molecular structures of the dyes in terms of the n-hexyl chains and methoxyl. The device sensitized by dye CM104 achieved the best conversion efficiency of 7.0% (J(sc) = 13.4 mA cm(-2), V(oc) = 704 mV, FF = 74.8%) under AM 1.5 irradiation (100 mW cm(-2)). In contrast, the device sensitized by reference dye CMR104 with the same donor but the cyanoacetic acid as the acceptor gave an efficiency of 3.4% (J(sc) =6.2 mA cm(-2), V(oc) = 730 mV, FF = 74.8%). Under the same conditions, the cell fabricated with N719 sensitized porous TiO(2) exhibited an efficiency of 7.9% (J(sc) = 15.4 mA cm(-2) , V(oc) = 723 mV, FF = 72.3%). The dyes CM101-CM104 show a broader spectral response compared with the reference dyes CMR101-CMR104 and have high IPCE exceeding 90% from 450 to 580 nm. Considering the reflection of sunlight, the photoelectric conversion efficiency could be almost 100% during this region.

Synthesis of New Substituted Pyridopyrazolotriazines

Pyrazolo[3,4- b ]pyridinediazonium chlorides react with a variety of active methylenecontaining reagents (e. g., cyanoacetic acid arylidenehydrazide derivatives) to afford the corresponding 3-hydrazonopyrazolo[3,4- b ]pyridine derivatives. The diazonium chlorides react with N '-acyl-2-cyanoacetohydrazide derivatives to give corresponding 3-hydrazonopyrazolopyridine derivatives. The latter affords corresponding 3-hydrazonopyrazolo[3,4- b ]pyridine derivatives on reflux in acetic acid. Diazocoupling of 2,4-dimethylpyrazolo[3,4- b ]pyridinediazonium chloride with ketoester, e. g. , ethyl benzoylacetate is followed by cyclization to afford pyrido[2',3':3,4]pyrazolo[5,1- c ]triazine derivative. Diazocoupling of the same dimethylpyrazolo[3,4- b ]pyridinediazonium chloride with unsymmetrical β-diketone, e. g. , benzoylacetone was also studied to afford the corresponding hydrazono derivative, which undergoes in situ cyclization to furnish the pyrido[2',3':3,4]pyrazolo[5,1- c ]triazine derivative. Also published in Chemistry of Heterocyclic Compounds , 2012, 48 (7), pp 1071-1077 http://link.springer.com/article/10.1007/s10593-012-1101-4

Hydrogen Bonding in Pyridine N-Oxide/Acid Systems: Proton Transfer and Fine Details Revealed by FTIR, NMR, and X-ray Diffraction

The H-bonded complexes of pyridine N-oxide (PyO) with H(2)O, acetic, cyanoacetic, propiolic, tribromoacetic, trichloroacetic, trifluoroacetic, hydrochloric, and methanesulfonic acids have been studied by FTIR and NMR spectroscopy, X-ray diffraction, and quantum chemical DFT calculations. Correlations between vibrational frequencies of the NO stretching and PyO ring modes and geometric parameters of the H-bond have been established. FTIR experiments show and DFT calculations confirm that definite discontinuity is present in the vicinity of the midpoint in the proton transfer pathway. The established correlations significantly aid in the understanding of fine effects such as the isotope (deuteration) effect, crystal-to-solution transition, or criticality of aqueous solutions induced by ionic pairs. Geometric isotope effect in the ionic H-bond aggregate of PyO·H(D)Cl was found to be extraordinary large. Measured FTIR, CP/MAS, and high-resolution (13)C NMR spectra indicate that H-bond in the PyO·HCl complex in polar solvent can potentially be more ionic than in the crystal. Vibrational modes of ionic pairs originating via proton transfer in H-bond complexes can provide new information concerning the interionic interaction and its role in the phase separation and mezo-structuring processes. The results are compared to the relevant data for PyO·HCl complex in argon matrix.

Carboxylic acid-catalyzed one-pot synthesis of cyanoacetylureas and their cyclization to 6-aminouracils in guanidine ionic liquid

A novel, one-pot, carboxylic acid-catalyzed synthesis of cyanoacetylureas via in situ generated ureas and their cyclization to 6-aminouracils in the presence of the guanidine-based ionic liquid 1,1,3,3-tetramethylguani- dine lactate (TMG)(Lac) is described. The ureas were synthesized from amines and potassium cyanate, which on reaction with cyanoacetic acid in the presence of acetic anhydride in the same pot afforded cyanoacetylureas, which undergo cyclization in (TMG)(Lac) as solvent as well as catalyst to afford 6-aminouracils. One-pot synthesis of cyanoacetylureas, efficient and rapid cyclization, better yield, shorter reaction time, easy workup procedure, and recyclability of the ionic liquid are some advantages of this procedure.

Effect of linker used in D–A–π–A metal free dyes with different π-spacers for dye sensitized solar cells

Two novel D–A–π–A metal free dyes with triphenylamine as donor, dithiophene-diketo-pyrrolo-pyrrole as acceptor unit, thiophene and phenyl π-conjugated bridges and a cyanoacetic acid as electron acceptor (TDPP1 and TDPP2 were denoted for thiophene and phenyl π-conjugated bridge, respectively) have been designed and used as sensitizers for DSSCs. Incorporation of dithiophene-diketo-pyrrolo-pyrrole, reduces the band gap significantly. The influence of π-conjugated bridge on optical and electrochemical properties were investigated. Results demonstrated that the absorption band of TDPP with thiophene π-conjugated bridge has red shifted due to the enhancement of electron donating ability of π-conjugated bridge. The DSSC based on TDPP1 shows prominent power conversion efficiency about 4.81%, which is higher that for TDPP2 (3.42%). The electrochemical impedance spectroscopy analysis reveal that the charge recombination resistance at the TiO2/dye/electrolyte interface for the DSSC based on TDPP1 is higher than that for TDPP2, which improves both Jsc and Voc. The PCE of the DSSC based on TDPP1 is further improved up to 6.34%, when deoxycholic acid (DCA) was employed as coadsorbant.

Synthesis, structure, photophysical, and electrochemical properties of donor–acceptor ferrocenyl derivatives

A series of donor–acceptor compounds 2–6 have been synthesized, via Knoevenagel condensation reaction (using conventional method, as well as microwave method). The ferrocene unit acts as a donor, conjugated phenyl–acetylene linker act as a π-electron relay unit, and malononitrile, cyanoacetic acid, and indanone groups act as acceptor. The electronic absorption spectra displayed a broad intramolecular charge transfer (CT) band in the visible region (450–650 nm). The electrochemical studies suggest considerable donor–acceptor interaction. The single crystal X-ray structure of 2, and 3 are reported, the structure reveals that 2 is nearly planar compared to 3. The supramolecular structure of 2 exhibits intramolecular C–H–π, and C–H–N interaction, which leads to formation of 2D network, whereas compound 3 shows head to tail dimer formation through C–H–π, and π–π interaction.

Template-Assisted Synthesis of Co,Mn-MOFs with Magnetic Properties Based on Pyridinedicarboxylic Acid

To investigate the influence of organic molecules with reactive functional groups as templates on the structures of the resulting MOFs, four novel complexes based on the pyridyl carboxylic acid ligand 5-(pyridin-4-yl)isophthalic acid (H2pyip), namely, [Mn3(pyip)2(HCOO)2(H2O)2]n (1), {[Co(pyip)(H2O)]·H2O}n (2), {[Mn2(pyip)2(H2O)4]·5H2O}n (3), and [Co(pyip)(EtOH)(H2O)]n (4), have been synthesized under solvothermal conditions. In the presence of 4,4′-bipyridyl as the template, 3D coordination framework 1 with the Schlafli symbol of (4·6·7) (42·5·65·73·82·9·11) was obtained. Using cyanoacetic acid as the template, we obtained 2D double-layered structure 2 with the Schlafli symbol of (43) (46·66·83). 3 and 4 are prepared in the absence of a templating agent. 3 features an infinite 2D network with a 1D water chain penetrating the 1D channel and further results in a 3D supramolecule through hydrogen-bond interactions. 4 contains two independent 2D networks that are further connected to a 2D double-layered supra...

Antitumor activity of novel pyridine, thiophene and thiazole derivatives

2-Cyano-N'-[1-(2,5-dimethoxyphenyl)]ethylideneacetohydrazide 1 was obtained via reaction of cyanoacetic acid hydrazide with 2,5-dimethoxyacetophenone. A number of novel pyridines 2a-j, 3, 4, thiophenes 5-9 and thiazoles 10-12 were prepared by using the hydrazide-hydrazone derivative 1 as a starting material. The structure of the newly synthesized compounds was characterized by elemental analyses, IR, (1)H-NMR, (13)C-NMR and mass spectral data. All the target compounds were subjected to in vitro antitumor activity against Ehrlich ascites carcinoma (EAC) cells. Compounds 2j and 6 showed a higher activity with IC(50) values (54.54, 61.57 μM), 8 when compared with a reference drug IC(50) value (68.99 μM), while compound 5 is nearly as active as doxorubicin (CAS 23214-92-8).

Constructing Organic D–A–π‐A‐Featured Sensitizers with a Quinoxaline Unit for High‐Efficiency Solar Cells: The Effect of an Auxiliary Acceptor on the Absorption and the Energy Level Alignment

Four organic D-A-π-A-featured sensitizers (TQ1, TQ2, IQ1, and IQ2) have been studied for high-efficiency dye-sensitized solar cells (DSSCs). We employed an indoline or a triphenylamine unit as the donor, cyanoacetic acid as the acceptor/anchor, and a thiophene moiety as the conjugation bridge. Additionally, an electron-withdrawing quinoxaline unit was incorporated between the donor and the π-conjugation unit. These sensitizers show an additional absorption band covering the broad visible range in solution. The contribution from the incorporated quinoxaline was investigated theoretically by using DFT and time-dependent DFT. The incorporated low-band-gap quinoxaline unit as an auxiliary acceptor has several merits, such as decreasing the band gap, optimizing the energy levels, and realizing a facile structural modification on several positions in the quinoxaline unit. As demonstrated, the observed additional absorption band is favorable to the photon-to-electron conversion because it corresponds to the efficient electron transitions to the LUMO orbital. Electrochemical impedance spectroscopy (EIS) Bode plots reveal that the replacement of a methoxy group with an octyloxy group can increase the injection electron lifetime by a factor of 2.4. IQ2 and TQ2 can perform well without any co-adsorbent, successfully suppress the charge recombination from TiO(2) conduction band to I(3)(-) in the electrolyte, and enhance the electron lifetime, resulting in a decreased dark current and enhanced open circuit voltage (V(oc)) values. By using a liquid electrolyte, DSSCs based on dye IQ2 exhibited a broad incident photon-to-current conversion efficiency (IPCE) action spectrum and high efficiency (η=8.50 %) with a short circuit current density (J(sc)) of 15.65 mA cm(-2), a V(oc) value of 776 mV, a fill factor (FF) of 0.70 under AM 1.5 illumination (100 mW cm(-2)). Moreover, the overall efficiency remained at 97% of the initial value after 1000 h of visible-light soaking.

Cyanoacetamides (IV): Versatile One-Pot Route to 2-Quinoline-3-carboxamides

Cyanoacetic acid derivatives are the starting materials for a plethora of multicomponent reaction (MCR) scaffolds. Herein, we describe scope of a valuable general protocol for the synthesis of arrays of 2-aminoquinoline-3-carboxamides from cyanoacetamides and 2-aminobenzaldehydes or heterocyclic derivatives via a Friedländer reaction variation. In many cases, the reactions involve a very convenient work up by simple precipitation and filtration. More than 40 new products are described. We foresee our protocol and the resulting derivatives becoming very valuable to greatly expanding the scaffold space of cyanoacetamide derivatives.

2-Aminothiophenes as building blocks in heterocyclic synthesis: Synthesis and antimicrobial evaluation of a new class of pyrido[1,2-a]thieno[3,2-e]pyrimidine, quinoline and pyridin-2-one derivatives

Multisubstituted 2-aminothiophenes 1a–c can be readily cyanoacylated via reaction with cyanoacetic acid in presence of acetic anhydride under a microwave irradiation to form the corresponding cyanoacetamides 2a–c, which condensed with DMF-DMA to form the corresponding enamines 4 that reacted with hydrazine hydrate to yield the aminopyrazoles 5. Moreover the cyanoacetamides 2a–c reacted with a variety of arylidenmalononitrile to afford a novel pyrido[1,2-a]thieno[3,2-e]pyrimidine derivatives 12a–o. In addition the enamines 4a,b reacted with malononitrile to afford the pyrido[1,2-a]thieno[3,2-e]pyrimidine derivatives 19a,b. The cyanoacetamides 2a,b reacted also with salicylaldehyde to afford the quinoline derivatives 24a,b. Moreover the cyanoacetamides 2a,b reacted with the enaminones 25a–c to form the corresponding Pyridin-2-one derivatives 29a–c. Reactions of 2a,c with bezenediazonium chloride afford the arylhydrazones 30a,b that reacted with chloroacetonitrile to form the acyclic product 31 which could not be further cyclized to the corresponding 4-aminopyrazole. The X-ray crystallographic analyses of seven products could be obtained thus establishing with certainty the proposed structures in this work. Most of the synthesized compounds in this investigation were tested and evaluated as antimicrobial agents.

Electrochemical impedance parameters elucidate performance of carbazole–triphenylamine–ethylenedioxythiophene-based molecules in dye-sensitized solar cells

Abstract Organic dyes are synthesized containing bridging ethylenedioxythiophenes (EDOT) between the electron donors and electron acceptors (2-cyanoacetic acid) on carbazole–triphenylamines. These compounds are then characterized by photophysical, electrochemical, and theoretical computational methods. Nanocrystalline TiO 2 -based dye-sensitized solar cells (DSSCs) are fabricated using these dye molecules as light-harvesting sensitizers. The overall efficiency of the sensitized cells is high (5.20%) compared to the efficiency of a cis-di(thiocyanato)-bis(2,2′-bipyridyl)-4,4′-dicarboxylate ruthenium (II) (N3 dye)-sensitized device (7.57%) fabricated and measured under the same conditions. The dye (ETPA3) containing one carbazole, two EDOT bridges, and two 2-cyanoacetic acid groups appears to assist in the charge transfer from the excited dye molecules to the conduction band of TiO 2 , leading to the higher efficiency of the devices using assembled with this dye. A supplementary study of the electrochemical impedance supports the enhancement of the charge transfer of TiO 2 (e − ) with the ETPA3 dye. A computational examination of the ETPA3 compound also indicates higher charge transfer efficiency in the electronically excited state.

Synthesis and mesomorphic properties of calamitic malonates and cyanoacetates tethered to 4-cyanobiphenyls.

4-Cyano-1,1'-biphenyl derivatives bearing ω-hydroxyalkyl substituents were reacted with methyl 3-chloro-3-oxopropionate or cyanoacetic acid, giving liquid-crystalline linear malonates and cyanoacetates. These compounds formed monotropic nematic phases at 62 °C down to ambient temperature upon cooling from the isotropic liquid. The mesomorphic properties were investigated by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction (WAXS).

The DFT investigations of the electron injection in hydrazone-based sensitizers

Quantum chemical calculations were carried out by using density functional theory and time-dependant density functional theory at B3LYP/6-31G(d) and TD-B3LYP/6-31G(d) level of theories. The absorption spectra have been computed with and without solvent. The calculated absorption spectra in ethanol, acetonitrile, and methanol are in good agreement with experimental evidences. The absorption spectra are red shifted compared to System1. On the basis of electron injection and electronic coupling constant, we have shed light on the nature of different sensitizers. The coplanarity between the benzene near anchoring group having LUMO and the bridge (N–N) is broken in System6 and System7 that would hamper the recombination process. The electron injection of System2–System10 is superior to System1. The highest electronic coupling constant has been observed for System6 that followed the System7 and System8. The light-harvesting efficiency of all the sensitizers enlarged in acetonitrile and ethanol. The long-range-corrected functional (LC-BLYP), Coulomb-attenuating method (CAM-B3LYP), and BH and HLYP functional underestimate the excitation energies while B3LYP is good to reproduce the experimental data. Moreover, we have investigated the effect of cyanoacetic acid as anchoring group on the electron injection.

Studies on 3-Oxoalkanenitriles: Novel Rearrangement Reactions Observed in Studies of the Chemistry of 3-Heteroaroyl-3-Oxoalkanenitriles as Novel Routes to 2-Dialkylaminopyridines

3-Aroyl and 3-heteroaroyl substituted 3-oxoalkanenitriles were synthesized by the reactions of activated aromatic and hetero-aromatic substances with cyanoacetic acid in the presence of acetic anhydride. As part of studies focusing on the preparation of cyanoacetyl-1-N-methylbenzimidazole, we observed that reaction of N-methyl-benzimidazole with the cyanoanhydride formed by condensation of cyanoacetic acid with acetic anhydride, leads to the formation of 2-(1,3-diacetyl-2,3-dihydro-1H-benzo[d]-imidazol-2-yl)acetonitrile (5), whose structure was confirmed by X-ray crystallographic analysis. 3-Oxoalkanenitriles 3a,b were observed to undergo condensation reactions with dimethylformamide dimethyl acetal (DMFDMA) to afford the corresponding enamino-nitriles, which react with malononitrile to give 2-dialkylaminopyridines through a pathway involving a new, unexpected rearrangement process. Reactions of 3-oxoalkanenitriles with ethyl acetoacetate were found to afford 2-oxopyran-3-carbonitriles, also occurring via this unexpected rearrangement process. Mechanisms to account for both rearrangement reactions are suggested. In addition, reactions of 3-oxoalkanenitriles with acetylacetone in acetic acid in the presence of ammonium acetate result in the formation of pyridine-3-carbonitriles. Finally, upon heating in the presence of zeolite 3-oxoalkanenitriles 3b,c self-trimerized to produce the corresponding aniline derivatives 23b,c.

Efficient Approach to Pure Entacapone and Related Compounds

A new and efficient process through a new intermediate, (2E)-2-cyano-3-(3,4-dihydroxy-5-nirtrophenyl)prop-2-enoic acid 15, has been described for preparing substantially pure entacapone 1. This new intermediate 15 was prepared by Knoevenagel condensation of 3,4-dihydroxy-5-nitrobenzaldehyde 2 with 2-cyanoacetic acid 14 and was further condensed with diethylamine to get pure entacapone 1. Some of the important process-related impurities of entacapone (17, 18, 19, and 20) were also prepared easily from this intermediate 15.

Phenothiazine–triphenylamine based organic dyes containing various conjugated linkers for efficient dye-sensitized solar cells

In order to increase the electron-donating ability of the donor part of the organic dye, two phenothiazine groups, as additional electron donors, were introduced into a triphenylamine unit to form a starburst donor–donor (2D) structure in this paper. Three new organic dyes (WD-6, WD-7 and WD-8) containing this starburst 2D structure and a 2-cyanoacetic acid acceptor linked by various conjugated linkers (benzene, thiophene, and furan) have been designed, synthesized and applied in dye-sensitized solar cells (DSSCs). The introduction of a phenothiazine group with a butterfly conformation in the triphenylamine donor parts has a good influence on preventing the molecular π–π aggregation due to the starburst 2D structure of the organic dye. The conjugated linker effects on the photophysical, electrochemical and photovoltaic properties of these organic dyes were investigated in detail. The DSSCs made with these organic dyes displayed remarkable overall conversion efficiencies, ranging from 4.90–6.79% under an AM 1.5 solar condition (100 mW cm−2). The best performance was found for organic dye WD-8, in which a furan group was the conjugated linker. It displayed a short-circuit current (Jsc) of 14.43 mA cm−2, an open-circuit voltage (Voc) of 682 mV, and a fill factor (ff) of 0.69, corresponding to an overall conversion efficiency of 6.79%. The different photovoltaic behaviors of the solar cells based on these organic dyes were further elucidated by the electrochemical impedance spectroscopy.

Effects of different acceptors in phenothiazine-triphenylamine dyes on the optical, electrochemical, and photovoltaic properties

In dye-sensitized solar cells (DSSCs), as the excited electrons from dye molecules are injected to the conduction band of semiconductor film through the acceptor moieties, the acceptor groups have significant influences on the photovoltaic properties of the dyes. In this paper, the effects of different acceptor groups (cyanoacetic acid and rhodanine-3-acetic acid) in two phenothiazine-triphenylamine dyes (PTZ-1 and PTZ-2) on the optical, electrochemical properties and photovoltaic performances were studied. In comparison with PTZ-2, the photovoltaic performance of PTZ-1 is significantly improved by replacing rhodanine-3-acetic acid to cyanoacetic acid. The conversion efficiency of solar cell based on the PTZ-1 is increased about 110%. The lower efficiency of solar cell based on PTZ-2 is mainly because the delocalization of the excited state is broken between the 4-oxo-2-thioxothiazolidine ring and the acetic acid, which affects the electron injection from PTZ-2 to the conduction band of TiO2.