Cyanoacetic Acid Research Articles

N-heterocyclic linkers from 1,2-diaza-1,3-dienes for dye-sensitized solar cells: DFT calculations, synthesis and photovoltaic performance

Organic dyes for dye-sensitized solar cells (DSSC) are generally constituted by chemical groups that act differently as electron donor (D) and acceptor (A) bridged by a linker. Three new push-pull D–π–A structured dyes (SIP1, SIP3, SIP4) having imidazo[1,2-a]pyridine heterocycles as additional π-conjugated linker were designed and synthesized. Triphenylamine (TPA) was introduced as electron-donor unit and cyanoacetic acid or double rhodanine acetic acid were employed as anchoring groups in different positions of the heterocyclic core. DSSC devices with these dyes were assembled and tested using different electrolytes and dye baths. Finally, the related photovoltaic performance was measured. The Voc values were found to influence the overall behaviour of the cells related to the electrolyte composition. DFT calculations showed a theoretical trend for the electron transfer ability of the different dyes, and correlation with the real photovoltaic performance was discussed.

Molecular design and theoretical investigation of new metal-free heteroaromatic dyes with D-π-A architecture as photosensitizers for DSSC application

Abstract Herein, we report design, synthesis and photovoltaic performance of four new metal-free heteroaromatic dyes ( P 1-4 ) with D-π-A architecture carrying electron donating carbazole core connected to four different electron withdrawing/anchoring groups, viz. cyanoacetic acid, rhodanine-3-acetic acid, barbituric acid and thiobarbituric acid and phenylene ring as a π-spacer. The newly designed P 1-4 were synthesized from carbazole derivative using Suzuki cross coupling approach followed by Knoevenagel condensation reaction. Their structures were confirmed by FTIR, NMR, Mass spectral and elemental analyses. The dyes were subjected to optical and electrochemical studies in order to investigate their absorption/emission behavior as well as HOMO/LUMO energies. The UV–vis spectral studies reveal that the P 1-4 showed λ max at 412, 439, 458 and 489 nm, respectively. Their optical band-gap is in the range of 2.17 to 2.61 eV and fluorescence quantum yield is in the order of 44–70%. From energy level diagram, it is clear that all the dyes possess good thermodynamic feasibility for electron injection into CB edge of TiO 2 as well as their regeneration from electrolyte system. The photovoltaic performance studies indicate that among the tested dyes, P 1 anchored with cyanoacetic acid displayed the highest IPCE (32%), resulting in improved PCE (1.94%), J SC (4.68 mA cm −2 ), V OC (0.588 V) and FF (70.3%) values, when compared to other dyes. Finally, DFT studies were performed using Turbomole 7.1 V software to investigate their electron cloud delocalization in HOMO/LUMO levels and theoretical absorption spectral data. The results reveal that the dye P 1 showed effective charge separation in its FMO levels, which has reflected in its ICT behavior and hence P 1 displayed the improved photovoltaic performance.

Malonic Acid Derivatives on Duty as Electron‐Withdrawing Units in Push–Pull Molecules

Based on the 2‐(N‐piperidinyl)thiophene central donor, 32 model push–pull molecules with systematically varied malonic acid‐derived peripheral acceptors have been prepared. Further property tuning has been achieved by modifying the π‐linker and the structural arrangement (linear vs. quadrupolar D–π–A systems). Malonic acid derivatives such as cyanoacetic acid, malondinitrile, diethyl malonate, Meldrum′s acid, and N,N′‐dibutyl(thio)barbituric acid as well as 1,3‐diketo analogues dimedone and indan‐1,3‐dione were employed as acceptor moieties. Knoevenagel condensation with four thiophene aldehydes afforded the target chromophores in satisfactory yields. The electron‐withdrawing abilities of malonic acid acceptors were examined both by experiment including X‐ray analysis, differential scanning calorimetry, electrochemistry, and UV/Vis absorption spectroscopy, and by DFT calculations. Details of the structure–property relationships have been elucidated. According to the increasing electron‐withdrawing ability, the widely used malonic acid acceptor units can be ordered: diethyl malonate ≤ cyanoacetic acid < malondinitrile < Meldrum's acid < dimedone ≤ N,N′‐dibutylbarbituric acid < indan‐1,3‐dione ≤ N,N′‐dibutylthiobarbituric acid.

Fused quinoline heterocycles X. First synthesis of new four heterocyclic ring systems 10-amino-6,9-disubstituted-[1,2,4]triazino[4′,3′:1,5]pyrazolo[4,3-c]quinoline derivatives

ABSTRACTA novel, simple, and efficient synthetic methodology for the synthesis of hitherto unreported tetracyclic 10-amino-6,9-disubstituted-[1,2,4]triazino[4′,3′:1,5]pyrazolo[4,3-c]quinolines, in one step, has been developed by coupling of various active methylene compounds with diazotized heterocyclic amines. Reacting 2,4-dichloroquinoline-3-carbonitrile (1) with cyanoacetic acid hydrazide (2) in the presence of triethylamine in refluxing MeOH gave the unexpected 3-amino-4-chloro-1H-pyrazolo[4,3-c]quinoline (4), instead of the desired tetracyclic ring system 3 (Scheme 1). Refluxing 4 with excess of cyclic secondary amines 5a–c in boiling dimethylformamide yielded the corresponding 4-amino-pyrazolo[4,3-c]quinolines 6a–c. Diazotization of compounds 4 and 6a–c with sodium nitrite and concentrated HCl at −5 °C gave the corresponding diazonium salts 17a–d, which were then subjected to couple with different active methylene nitriles, namely, 2-cyanothioacetamide (12), ethyl cyanoacetate (13), malononitrile (14), 2-cyanoacetamide (15), and 2-cyano-N-phenylacetamide (16), in aqueous ethanol containing sodium acetate as a buffer solution. The coupling reaction of diazonium salts 17 with 12, 13, and 14 leading to the novel perianellated tetracyclic ring system 10-amino-6,9-disubstituted-[1,2,4]triazino[4′,3′:1,5]pyrazolo[4,3-c]quinolines 19, 23, and 27, respectively, in one step, is described for the first time. On the other hand, coupling reaction of diazonium salt 17a with both 15 and 16 yielded the previously unknown tetracyclic 10-amino-6-chloro-[1,2,4]triazino[4′,3′:1,5]pyrazolo[4,3-c]quinoline-9-carboxamides 28a and 28b, respectively (Scheme 6). No chromatographic techniques have been used for the purification of the products. The structures of all the newly synthesized compounds were unambiguously confirmed by spectroscopic and analytical techniques.

Synthesis and physicochemical properties of merocyanine dyes based on dihydropyridine and fragments of cyanoacetic acid derivatives

Synthesis and physicochemical properties of merocyanine dyes based on dihydropyridine and fragments of cyanoacetic acid derivatives

New benzoselenadiazole-based D–A–π–A type triarylamine sensitizers for highly efficient dye-sensitized solar cells

Three new D–A–π–A configuration organic dyes (LC-6, LC-7 and LC-8) based on triphenylamine as the electron donor, benzoselenadiazole (BSD) as the auxiliary acceptor, either thiophene or benzene as the π spacer and cyanoacetic acid as the anchoring group have been designed and synthesized for dye-sensitized solar cells (DSCs). Introduction of octyloxy chain on the triphenylamine unit was found to be able to redshift the absorption spectra and suppress the charge recombination. It was also found that using the benzene instead of thiophene as π spacers and using CDCA coadsorbent could help to improve the Jsc and Voc values of the cell. Under standard global AM 1.5 solar light conditions, a DSC employing a dye with a 1,4-phenylene unit with CDCA gave the best photovoltaic performance with a Jsc of 13.21 mA cm−2, a Voc of 734 mV, a FF of 0.69 and an overall PCE of 6.72%. These results suggest that the BSD unit can be a promising electron-withdrawing candidate in D–A–π–A type sensitizers for further exploration DSCs.

Carbazole-based compounds containing aldehyde and cyanoacetic acid: optical properties and applications in photopolymerization

Carbazole-based aldehyde and cyanoacetic acid containing dyes were synthesized and applied as photosensitizers in photopolymerization with a LED light source at 455 nm.

Effect of structural optimization on the photovoltaic performance of dithieno[3,2-b:2′,3′-d]pyrrole-based dye-sensitized solar cells

Five novel organic push–pull dyes, DT, CD-T, TD-T, CD-C and TD-P, based on carbazole or triphenylamine as donors, dithieno[3,2-b:2′,3′-d]pyrrole as a π-spacer and cyanoacetic acid as an acceptor were synthesized, and their structures were optimized for DSSCs.

ChemInform Abstract: Decarboxylative [4 + 1] Oxidative Annulation of Malonate Monoesters with 2‐Vinylpyridine Derivatives.

Abstract2‐Vinylpyridines or related N‐heterocycles participate with both malonate monoesters and cyanoacetic acid in a NIS‐mediated decarboxylative [4 + 1] oxidative annulation reaction.

Molecular Engineering of Triphenylamine Based Aggregation Enhanced Emissive Fluorophore: Structure-Dependent Mechanochromism and Self-Reversible Fluorescence Switching

Triphenylamine (TPA), a propeller-shaped optoelectronic molecule, has been used to generate stimuli-responsive smart fluorescent organic materials and correlate the effect of subtle structural changes on the molecular packing and mechanochromic fluorescence (MCF). The substituent (OCH3) position in the TPA phenyl ring and acceptors (malononitrile, cyanoacetamide, cyanoacetic acid, ethyl cyanoacetate, and diethylmalonate) strongly influenced the solid state and mechanochromic fluorescence as well as the molecular packing. The structure–property studies revealed that (i) TPA derivatives without the OCH3 substituent exhibit strong fluorescence (Φf = 85% (TCAAD-1, 55% (TDEM)), (ii) higher dihedral angle (τ) between donor (aminophenyl) and acceptor lead to weak/non fluorescent material, (iii) substituent at the ortho position to acceptor increased the dihedral angle (τ = 26.49 (TCAAD-2), τ = 27.14 (TDMM)), and (iv) the increase of alkyl groups produced self-reversible high contrast off-on fluorescence switchin...

Thionation of a cyanoxime derivative to form the sulphur-containing derivative, a novel ligand for complexation with transitional metal ions

2-Cyano-2-(hydroxyimino)dithioacetic acid was prepared starting from cyanoacetic acid methylester via 2-cyano-2-(hydroxyimino)acetic acid methylester. Before thionation, the ester had to be hydrolyzed. The optimum conditions for each reaction were identified. P4S10 was found to be the efficient thionation reactant resulting in the formation of the dithionated product. Its structure was verified with IR, NMR and mass spectrometric measurements.

Design and Synthesis of Novel Chromophore with Multi-Carboxyl Groups

ABSTRACTIn order to explore the application of organic conjugated small molecules in bioimaging, a novel functional chromophore with A-π-D-π-A structure (Cr-3) was synthesized through Knoevenagel condensation reaction, consisting of carbazole unit as electron donor and cyanoacetic acid as electron acceptor groups. To improve the water solubility of this conjugated molecule, three carboxyl groups were introduced to chromophore Cr-3. Compared to the traditional D-π-A chromophores, chromophore Cr-3 showed the great improvement in water with the solubility of 2000 ppm. Also, the thermal stability of chromophore Cr-3 was also studied. The thermal decomposition temperature (Td) of Cr-3 was approximately 180°C, which was attributed to the dehydration of the carboxyl groups. Though the second harmonic generation (SHG) effect was not very high, it is large enough for the detection of SHG signal in water solution (0.28 pm/V).

TANDEM KNOEVENAGEL CONDENSATION AND INTRAMOLECULAR CYCLOADDITION REACTIONS OF 2-AZIDOBENZALDEHYDES WITH 2-CYANOACETAMIDES IN THE SYNTHESIS OF 4-THIOCARBAMOYLTETRAZOLO[1,5- a ]QUINOLINES

The reaction of 2-azidobenzaldehydes with 2-thioamides of cyanoacetic acid proceeds without a solvent and presence of a base at 80–90°C selectively by one of the possible routes to form tetrazolo[1,5- a ]quinolines. The proposed mechanism of the reaction involves the Knoevenagel condensation and subsequent intramolecular [3+2] cycloaddition of the azide group at the S≡N bond of an intermediate acrylonitrile. Authors: Valery O. Filimonov, Vladimir T. Abaev, Tatyana V. Berezkina, Kristina A. Galata, Pavel A. Slepukhin, Maria A. Kostenko, Vera S. Berseneva*

Multichromophoric sensitizers based on calix[4]arene scaffold and 4H-pyranylidene moiety for DSSCs application

We have synthesized lower rim 1,3-derivatives of 4-tert-butylcalix[4]arene-appended dyes in order to test their physical and photovoltaic properties. These dyes consist in a donor group based on triphenylamine and/or 4H-pyranylidene moieties, a heteroaromatic π-conjugated spacer such a thiophene ring and an acceptor group like cyanoacetic acid. The molar extinction coefficient of these systems increases with the introduction of the second dye in the same molecule and it is observed an extended band along the visible spectrum. The use of calix[4]arene platform with other dyes could lead to a new strategy to the achievement of novel panchromatic dyes.

Tandem Knoevenagel Condensation and Intramolecular Cycloaddition Reactions of 2-Azidobenzaldehydes with 2-Cyanoacetamides in the Synthesis of 4-Thiocarbamoyltetrazolo-[1,5-a]Quinolines

The reaction of 2-azidobenzaldehydes with 2-thioamides of cyanoacetic acid proceeds without a solvent and base at 80–90°C selectively by one of the possible routes to form tetrazolo[1,5-a]quinolines. The proposed mechanism of the reaction involves the Knoevenagel condensation and subsequent intramolecular [3+2] cycloaddition of the azide group at the C≡N bond of an intermediate acrylonitrile.

Synthesis and characterization of novel thieno[3,2-b]thiophene based metal-free organic dyes with different heteroaromatic donor moieties as sensitizers for dye-sensitized solar cells

Four novel heterocycle dyes 3a-d were synthesized in order to study the variations produced in the optical, electronic and photovoltaic properties by substitution of different electron-rich heterocyclic groups to the thieno[3,2-b]thiophene system. The final push-pull conjugated dyes 3a-d were synthesized by Suzuki-Miyaura coupling reaction followed by Knoevenagel condensation of the corresponding aldehyde precursors with cyanoacrylic acid 2a-d. These new push-pull systems are based on a thieno[3,2-b]thiophene spacer, a cyanoacetic acid anchoring group and several electron-rich heterocycles (thiophene, pyrrole and furan) as donor groups. The multidisciplinary study concerning the optical, redox and photovoltaic characterization of the dyes reveals that compound 3b bearing a hexyl-bithiophene donor group/heterocyclic spacer exhibits the best overall conversion efficiency (2.49%) as sensitizer in nanocrystalline TiO2 dye sensitized solar cells. Co-adsorption studies between N719 and 3b revealed that upon addition of N719 co-adsorbent, the optimized cell efficiencies were improved by 16–77%. The best efficiency was 4.40%, corresponding to 54% of the photovoltaic performance of the N719-based DSSC fabricated and measured under similar conditions.

Modified pyrene based organic sensitizers with thiophene-2-acetonitrile as π-spacer for dye sensitized solar cell applications

Designed, synthesized and characterized two new metal free organic sensitizers for dye-sensitized solar cells (DSSCs) applications comprising pyrene-1-carbaldehyde as donor, thiophene-2-acetonitrile as π-spacer and cyano acetic acid or rhodanine-3-acetic acid as electron acceptor moieties. From photophysical properties, J and H- type dye aggregations observed for the cyano acetic acid and rhodanine-3-acetic acid anchor group based dyes respectively. The electrochemical experiments and time-correlated single-photon counting (TCSPC) measurements indicate the ability of electron injection into the TiO2 conduction band from the excited sensitizer. Theoretical calculations were performed to rationalize the experimental data and both experimental and theoretical studies indicate that rhodanine-3-acetic acid anchor groups at the acceptor moiety inhibit the electron injection process due to H-type dye aggregation which in turn decreases the open circuit voltage (Voc). Furthermore, the electrochemical impedance spectroscopy (EIS) experiments suggest that the effective electron injection, low charge transfer resistance (Rct), longer lifetime of dye on TiO2 film assists the increase of Voc, achieved by the addition of co-adsorbent deoxycholic acid which in turn enhances the power conversion efficiency (η%).

Synthesis, structure and physical properties of a low dimensional compound

The crystal structure of (μ3-oxo)hexakis(cyanoacetato-κO,O′)(cyanoacetato-κO)diaquatriiron(III) cyanoacetic acid shows the formation of trinuclear complexes in a hydrogen-bond network that bonds all the molecules in a 3D arrangement. For this complex, within whose clusters the whole magnetic interaction takes place, 57Fe Mössbauer spectroscopy shows that the Fe cations are in the S=5/2 state in the temperature range 2–295K. The asymmetric broadening of the absorption peaks below 80K is consistent with strong antiferromagnetic interactions between the metal spins. The magnetization measurements also show the antiferromagnetic character of the spin ensemble and an ST=1/2 magnetic ground state typical of triangular systems with similar J between Fe-Fe pairs.

Microwave‐Assisted Synthesis of Arylazoaminopyrazoles as Disperse Dyes for Textile Printing

AbstractThe synthesis of heterocyclic azo‐dyes via conventional heating and microwave (MW) heating was investigated. From a sequence of reactions starting from cyanoacetic acid, 4‐arylazo‐2H‐pyrazol‐3‐ylamines and 4‐arylazo‐2‐phenyl‐2H‐pyrazol‐3‐ylamines were obtained. The structures these compounds were obtained by inspection of spectroscopic and analytical techniques including 1H and 13C NMR spectroscopy, IR spectroscopy, mass spectrometry, and elemental analysis. The fastness properties and UV/Vis absorption spectroscopic data of these disperse dyes in printing polyester fabrics were investigated.

Synthesis of the derivatives of 6‐amino‐uracil labelled with 14C

The radioactively labelled 6-amino-5-nitroso-uracil (1) and 5-acetyl-6-amino-1,3-dimethyl-uracil (2) were required for metabolic studies to assess their suitability as drug candidates. A common precursor for both compounds was [cyano-14 C]cyanoacetic acid (6), readily prepared from potassium [14 C]cyanide. ACS reagents, namely, diethyl ether, acetic acid and acetic anhydride, had to be rigorously repurified to achieve a successful synthesis of 14 C-labelled compounds on a tenth-of-a-milligramme scale. 6-Amino-5-nitroso-[6-14 C]uracil (1-14 C) (0.55 mCi) was prepared with radiochemical purity > 98% and specific activity (SA) = 55.6 mCi/mmol. 5-Acetyl-6-amino-1,3-dimethyl-[6-14 C]uracil (2-14 C) (8 mCi) was prepared with radiochemical purity > 97% and SA = 55.6 mCi/mmol. It has been shown that a SA assay can be made from standard 13 C NMR spectra, thus avoiding the need to perform lengthier inverse-gated 13 C NMR experiments.