An efficient synthesis of 5′-(4-cyanophenyl)-2,2′-bifuran-5-carbonitrile and analogues

Design, synthesis, and performance evaluation of TiO2-dye sensitized solar cells using 2,2'-bithiophene-based co-sensitizers

We report on the synthesis and characterization of six novel 2,2'-bithiophene-based organic compounds (3a-c and 5a-c) that are designed to serve as co-sensitizers for dye-sensitized solar cells (DSSCs) based on TiO2. The compounds are linked to various donor and acceptor groups, and we confirm their chemical structures through spectral analyses. Our focus is on enhancing the performance of metal based N3, and the compounds were designed to operate at the nanoscale. We performed absorption and fluorescence emission measurements in dimethylformamide (DMF), where one of our compounds 5a exhibited the longest maximum absorption and maximum emission wavelengths, indicating the significant impact of the para methoxy group as a strong electron-donating group. Our dyes 5a + N3 (η = 7.42%) and 5c + N3 (η = 6.57%) outperformed N3 (η = 6.16%) alone, where the values of short current density (JSC) and open circuit voltage (VOC) for these two systems also improved. We also investigated the charge transfer resistance at the TiO2/dye/electrolyte interface using electrochemical impedance spectroscopy (EIS), which is important in the context of nanotechnology. According to the Nyquist plot, the 5a + N3 cocktail exhibited the lowest recombination rate, resulting in the highest VOC. Our theoretical calculations based on density functional theory (DFT) are also in agreement with the experimental process. These findings suggest that our compounds have great potential as efficient DSSC co-sensitizers. This study provides valuable insights into the design and synthesis of new organic compounds for use as co-sensitizers in DSSCs based on TiO2 and highlights the potential of these compounds for use in efficient solar energy conversion.

Novel pyrimidine-bichalcophene derivatives as corrosion inhibitors for copper in 1 M nitric acid solution

This study targets the investigation of three pyrimidine-bichalcophene derivatives (MA-1230, MA-1231, MA-1232) for the prevention of corrosion on copper in 1 M HNO₃ via weight loss (WL), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) techniques. The surface morphology was also analyzed by different methods. It was found that the inhibition efficiency (% η) increased by increasing the doses of pyrimidine derivatives and the temperature of the medium. Weight loss data revealed the better adsorption of MA-1232 on the Cu surface at increased inhibitor dose, reaching a maximum efficiency of 99.14% at a dose of 21 μM at 45 °C. The best description of the adsorption of the investigated derivatives on the copper surface was given by the Langmuir isotherm. Some important thermodynamic parameters for the studied inhibitors were computed and are discussed herein. The polarization studies showed that the pyrimidine-bichalcophenes act as mixed inhibitors. Computational chemical approaches were used with informative yields, including quantum-chemical and molecular dynamics simulation techniques, which agree with the experimental results. The results obtained from all tested methods are strongly accepted.

Indole and Benzimidazole Bichalcophenes: Synthesis, DNA Binding and Antiparasitic Activity

A novel series of indole and benzimidazole bichalcophene diamidine derivatives were prepared to study their antimicrobial activity against the tropical parasites causing African sleeping sickness and malaria. The dicyanoindoles needed to synthesize the target diamidines were obtained through Stille coupling reactions while the bis-cyanobenzimidazoles intermediates were made via condensation/cyclization reactions of different aldehydes with 4-cyano-1,2-diaminobenzene. Different amidine synthesis methodologies namely, lithium bis-trimethylsilylamide (LiN[Si(CH3)₃]₂) and Pinner methods were used to prepare the diamidines. Both types (indole and benzimidazole) derivatives of the new diamidines bind strongly with the DNA minor groove and generally show excellent in vitro antitrypanosomal activity. The diamidino-indole derivatives also showed excellent in vitro antimalarial activity while their benzimidazole counterparts were generally less active. Compound 7c was highly active in vivo and cured all mice infected with Trypanosoma brucei rhodesiense, a model that mimics the acute stage of African sleeping sickness, at a low dose of 4 × 5 mg/kg i.p. and hence 7c is more potent in vivo than pentamidine.

Experimental and theoretical studies on corrosion inhibition of 4-amidinophenyl-2,2′-bifuran and its analogues in acidic media

Corrosion inhibition studies of carbon steel (CS) in 1 M HCl by newly synthesized bichalcophene compounds namely; 4-(2,2′-bifuran-5-yl)benzamidine (MA-0947) and 6-(2,2′-bifuran-5-yl)nicotinamidine (MA-0941) and 6-[5-(thiophen-2-yl)furan-2-yl]nicotinamidine (MA-0940).

SYNTHESIS OF NOVEL BITHIOPHENE-SUBSTITUTED HETEROCYCLES BEARING CARBONITRILE GROUPS

Symmetrical and unsymmetrical bithiophene-substituted heterocycles bearing carbonitriles including imidazo[1,2-a]pyridine, benzimidazole, and pyridine derivatives have been synthesized via different synthetic protocols. The bithiophene bis-imidazo[1,2-a]pyridine derivatives 3a,b were achieved in three steps starting from 2-acetyl-5-bromothiophene. Suzuki coupling reaction of 2a with 5-formylthiophen-2-ylboronic acid forms the formyl derivative 5, which by condensation with 3,4-diaminobenzonitrile in the presence of sodium bisulfite furnishes the unsymmetrical bithiophene derivative 6. The bis-benzimidazole derivative 8 was obtained via hexabutylditin-mediated homocoupling of 5-bromothiophene-2-carboxaldehyde, while the benzimidazole derivatives 12a,b were prepared via the formyl derivatives 11a,b, a product of Velsmier formylation reaction of 10a,b. Two synthetic protocols for the aryl/hetaryl-2,2'-bithiophene derivative 14 have also been presented. In addition, the guanyl hydrazones of bithiophenes, 16 and 17, were prepared from bis(tri-n-butylstannyl)-2,2'-bithiophene through a Stille coupling reaction followed by a condensation step.

Dicationic phenyl-2,2'-bichalcophenes and analogues as antiprotozoal agents

A series of phenyl-2,2'-bichalcophene diamidines 1a-h were synthesized from the corresponding dinitriles either via a direct reaction with LiN(TMS)₂, followed by deprotection with ethanolic HCl or through the bis-O-acetoxyamidoxime followed by hydrogenation in acetic acid and EtOH over Pd-C. These diamidines show a wide range of DNA affinities as judged from their ΔT(m) values which are remarkably sensitive to replacement of a furan unit with a thiophene one. These differences are explained in terms of the effect of subtle changes in geometry of the diamidines on binding efficacy. Five of the eight compounds were highly active (below 6 nM IC₅₀) in vitro against Trypanosoma brucei rhodesiense (T. b. r.) and four gave IC₅₀values less than 7 nM against Plasmodium falciparum (P. f.). Only one of the compounds was as effective as reference compounds in the T. b. r. mouse model for the acute phase of African trypanosomiasis.