N-substituted Carbazole Derivatives Research Articles

Experimental and theoretical investigation of the substitution effects on N-substituted carbazole derivatives functionalized with azomethine bonds

Examining the structural, spectroscopic, and electronic properties of molecules using both theoretical and experimental methods allow to reveal their structure-property relationship. In this study, the structural and electrochemical properties of the newly synthesized N-substituted carbazole monomers with aniline (ACA), p-methylaniline (ACMA) and pentafloroaniline (ACFA) by using a combination of experimental and computational methods have been comparatively presented. Theoretically optimized molecular structures of newly synthesized monomers have been determined by Density Functional Theory (DFT) method with 6-31G(d,p) basis set. The structural, spectroscopic, and electronic characterizations of monomers have been performed by various techniques including 1H NMR, FT-IR, and UV–Visible spectroscopy. Electrochemical polymerizations of monomers were carried out in a 0.1 M LiClO4/DCM/ACN (5:95, V: V) system. Compared to other monomers, the substitution of fluorine atoms has led to an anodic shift of the oxidation potential of the ACFA. Electrochemical and electrochromic properties of the obtained conductive polymers have been comparatively investigated by cyclic voltammetry and spectroelectrochemistry techniques. It has been observed that the poly(E)-N-(4-(9H-carbazol-9-yl) benzylidene) aniline (PACA) polymer film shows higher optical contrast, fast response time, and good electrochemical stability compared to the poly (E) N - (4- (9H-carbazol-9-yl) benzylidene) -4-methylaniline (PACMA) polymer film.

Elucidation of antimicrobial activity and mechanism of action by N-substituted carbazole derivatives

Compounds belonging to a carbazole series have been identified as potent fungal plasma membrane proton adenosine triphophatase (H+-ATPase) inhibitors with a broad spectrum of antifungal activity. The carbazole compounds inhibit the adenosine triphosphate (ATP) hydrolysis activity of the essential fungal H+-ATPase, thereby functionally inhibiting the extrusion of protons and extracellular acidification, processes that are responsible for maintaining high plasma membrane potential. The compound class binds to and inhibits the H+-ATPase within minutes, leading to fungal death after 1–3h of compound exposure in vitro. The tested compounds are not selective for the fungal H+-ATPase, exhibiting an overlap of inhibitory activity with the mammalian protein family of P-type ATPases; the sarco(endo)plasmic reticulum calcium ATPase (Ca2+-ATPase) and the sodium potassium ATPase (Na+,K+-ATPase). The ion transport in the P-type ATPases is energized by the conversion of ATP to adenosine diphosphate (ADP) and phosphate and a general inhibitory mechanism mediated by the carbazole derivative could therefore be blocking of the active site. However, biochemical studies show that increased concentrations of ATP do not change the inhibitory activity of the carbazoles suggesting they act as allosteric inhibitors. Furthermore decreased levels of intracellular ATP would suggest that the compounds inhibit the H+-ATPase indirectly, but Candida albicans cells exposed to potent H+-ATPase-inhibitory carbazoles result in increased levels of intracellular ATP, indicating direct inhibition of H+-ATPase.

Recent Developments and Biological Activities of N-Substituted Carbazole Derivatives: A Review.

Carbazoles represent an important class of heterocycles. These have been reported to exhibit diverse biological activities such as antimicrobial, antitumor, antiepileptic, antihistaminic, antioxidative, anti-inflammatory, antidiarrhoeal, analgesic, neuroprotective and pancreatic lipase inhibition properties. A series of carbazole derivatives such as N-substituted carbazoles, benzocarbazoles, furocarbazoles, pyrrolocarbazoles, indolocarbazoles, imidazocarbazoles, etc. have been synthesized. The N-substituted derivatives have gained the attention of researchers due to their therapeutic potential against neurological disorders and cell proliferation. Herein an attempt is made to review the medicinal importance of recently synthesized N-substituted carbazoles.

Antiseptic Effects of New 3'-N-Substituted Carbazole Derivatives In Vitro and In Vivo.

Inhibition of high-mobility group box 1 (HMGB1) protein and restoration of endothelial integrity are emerging as attractive therapeutic strategies in the management of sepsis. Here, new five structurally related 3'-N-substituted carbazole derivatives were examined for their effects on lipopolysaccharide (LPS)-mediated or cecal ligation and puncture (CLP)-mediated release of HMGB1 and on modulation of HMGB1-mediated inflammatory responses. We accessed this question by monitoring the effects of posttreatment carbazole derivatives on LPS- and CLP-mediated release of HMGB1 and HMGB1-mediated regulation of proinflammatory responses in human umbilical vein endothelial cells (HUVECs) and septic mice. The new 3'-N-substituted carbazole derivatives 1-5 inhibited the release of HMGB1 and downregulated HMGB1-dependent inflammatory responses in human endothelial cells. New compounds also inhibited HMGB1-mediated hyperpermeability and leukocyte migration in mice. In addition, treatment with each compound reduced CLP-induced release of HMGB1 and sepsis-related mortality and pulmonary injury in mice. These results indicate that the new 3'-N-substituted carbazole derivatives could be candidate therapeutic agents for various severe vascular inflammatory diseases owing to their inhibition of the HMGB1 signaling pathway.

Synthesis, antibacterial and antifungal activities of some carbazole derivatives

A series of N-substituted carbazole derivatives were synthesized and evaluated for antibacterial and antifungal activities against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Bacillus proteus, Candida albicans and Aspergillus fumigatus by two fold serial dilution technique. Some of the synthesized compounds displayed comparable or even better antibacterial and antifungal activities than reference drugs fluconazole, chloramphenicol and norfloxacin against tested strains.

Bichromophores symétriques: torsion intramoléculaire sans transfert de charge à l'état électronique excité S 1 dans le dicarbazyle- N,N′

N,N′-dicarbazyl (NNDC) was investigated in the gas phase and in fluid and rigid solutions of non-polar and polar protic and aprotic solvents over a wide temperature range (77 – 300 K). A comparison of the spectral and photophysical parameters in a series of N-substituted carbazole derivatives allows us to conclude that the symmetry of the relaxed excited singlet S 1 state in NNDC has been lowered compared with that in the electronic ground state. We have shown that the 90° geometry in the excited Franck—Condon state is transformed to an oblique geometry through intramolecular interaction processes only. This is in contrast with the only other well-studied symmetrical bichromophoric system, 9,9′-bianthryl, where a polar-solvent-induced charge transfer operates in the Franck—Condon excited state relaxation process.