An efficient and versatile synthesis of 2, 2'-(alkanediyl)-bis-1H-benzimidazoles employing aqueous fluoroboric acid as catalyst: density functional theory calculations and fluorescence studies
作者:Chhanda Mukhopadhyay、Sabari Ghosh、Ray J. Butcher
DOI:10.3998/ark.5550190.0011.908
日期:——
Alkanediyl)-bis-1H-benzimidazoles (simple and mixed) with variable methylene spacers were synthesized in excellent yields with aqueousfluoroboricacid (45%) (0.1 ml) as catalyst under solvent-free conditions. Their optimized structures were obtained using DFT calculations where it was seen that the s-trans orientation of the two imidazole rings was preferred for all types of bis-benzimidazole systems
Bisbenzimidazole Derivatives as Potential Antimicrobial Agents: Design, Synthesis, Biological Evaluation and Pharmacophore Analysis
作者:Ronak Haj Ersan、Kayhan Bolelli、Serpil Gonca、Aylin Dogen、Serdar Burmaoglu、Oztekin Algul
DOI:10.1007/s11094-021-02389-x
日期:2021.5
In an attempt to design and synthesize a potent class of antimicrobials, 1,2-phenylenediamine derivatives were reacted with various aliphatic and heteroaliphatic dicarboxylic acids to generate a small library of 26 head-to-head bisbenzimidazole compounds (16 – 42) using the polyphosphoric acid method. These compounds were screened for their antibacterial activity and their antifungal activity. Compound 25 showed maximum potency against both Gram-positive and Gram-negative bacterial strains with minimum inhibitory concentration (MIC) values in the range of 7.81 – 31.25 μg/mL. In particular, it showed the maximum MIC values of 7.81 μg/mL against Gram-negative bacteria, which was four-fold more active than the standard drug ampicillin (MIC = 32.25 μg/mL). Compound 19 was found to be the most active against S. aureus with a MIC value of < 3.90 μg/mL, whereas the remaining compounds showed only low-to-moderate activity. Furthermore, all compounds exhibited low activity against all fungal strains in comparison to the standard drug fluconazole. I addition, pharmacophore hypotheses were generated to analyze structure–activity relationships between the molecular structures and antimicrobial activities on E. coli. This pharmacophore model can be useful in order to design new antimicrobial drugs. It can be suggested that the substitution of a phenyl ring at the 5/6 and 5′/6′ positions in symmetric bisbenzimidazole derivatives produces compounds with promising antimicrobial activity.
Unraveling the molecular recognition of “three methylene spacer” bis(benzimidazolium) moiety by dibenzo-24-crown-8: pseudorotaxanes under study
作者:Chhanda Mukhopadhyay、Sabari Ghosh、Ann Marie Schmiedekamp
DOI:10.1039/c1ob06311a
日期:——
âThree methylene spacerâ bis(benzimidazolium) derivatives act as a new template for threading dibenzo-24-crown-8 into [2]pseudorotaxanes. In this Article we sought to unveil the difference in the extent of threading of various âthree methylene spacerâ bis-benzimidazolium moieties based on differences in aromatic methyl substituent positions and anions through the macrocycle dibenzo-24-crown-8. The temperature of the systems were also varied (low temperatures of 240 K and 253 K), when such interwinding of the thread and crown were not detected at room temperature of 308 K. The presence of such threaded complexes was determined based on 1H-NMR initially and finally corroborated by high resolution mass spectrometry and DFT calculations. 2D-NMR experiments (1Hâ1H-NOESY) proved to be a very important tool in elucidating the interaction present between the components of the pseudorotaxanes. The dethreading/rethreading process was studied. DFT optimized structures suggest lower energy H-bonding orientations and compare the effect of methyl substituents on the axle.