Synthesis of novel 1,10-phenanthroline derivatives and it used as probes for sensitive detection of Zn2+ and Cd2+ metal ions - Spectroscopic and theoretical approach.

A novel class of unexpected 1,10-phenanthrolinederivatives were synthesized from 2,3-dihydroacridin-4(1H)-ones with 3-aminonaphthalen-2-carboxylic acid in presence of phosphorus oxychloride at 130°C and simple perceptive emission intensity increasing assay was developed effectively to detect the very low concentrations of Zn2+ and Cd2+ ions. Emission intensity of compounds 3(a-c) directly related to the concentrations of Zn2+ and Cd2+ ions was due to metal chelating enhanced fluorescence (CHEF) effect and also its further validated by fluorescence lifetime measurement. Furthermore, the sensing mechanism for compounds 3(a-c) of Zn2+ and Cd2+ were sustained by theoretical calculations. Computational analysis results reveals that compounds 3(a-c) are more interested in Zn2+ ions than that of Cd2+ ions, while, compound 3c is more interested with Zn2+ and Cd2+ ions than those of the rest of the compounds. In addition, this proposed detection analysis has the direct application for monitoring Zn2+ and Cd2+ concentrations in tap and drinking water samples.

Convenient framework of poly functionalized (E)-2-benzylideno-(Z)-carbazolylideno cyanoacetamides via rearrangements as an efficient antibiofilm inhibitors with SAR study.

A simple and one-pot approach for the synthesis of highly functionalized novel (E)-2-benzylideno-(Z)-carbazolylideno cyanoacetamide derivatives from different 2-(2',3',4',9'-tetrahydro-carbazol-1'-ylidene)-propanedinitriles and aryl/heteroaryl carbaldehydes via vinylogous aldol reaction. The structures of the molecules were designated by FT-IR, 1H NMR, 13C NMR studies, elemental and X-ray crystallographic analysis. The synthesized pure products have been screened for in vitro antibiofilm inhibitory activity towards antibiotic-resistant pathogenic organisms. All the synthesized compounds showed biofilm inhibition. Promisingly, the moieties 3a, 3d and 3h showed higher antibiofilm activity at biofilm inhibitory concentration (BIC) (200 µg/mL) against bacterial pathogens. Among the three moieties, 3a showed high prospective against E. coli biofilm with minimal and maximal BIC percentage of 32% (10 µg/mL) and 89% (100 µg/mL) and chosen lowest BIC for further evaluation. Also, the 3a generate ROS two fold at 1 h treatment in E. coli biofilm. The 3a exhibited no toxic effect on cell viability upto 75 µg/mL in HEK293 cell lines. The results of the present study reveal that among (E)-2-benzylideno-(Z)-carbazolylideno cyanoacetamides, (E)-2-benzylideno-6-methyl-2,3,4,9-tetrahydro-1H-carbazol-(Z)-α-carbamino-α-cyano-1-ylidene (3a) could be exploited as an excellent antibiofilm agent against carbapenem-resistant E. coli bacteria strains.

A new strategy for the synthesis of diverse benzo[a]carbazoles via a divergent catalytic Michael reaction.

A new type of divergent tandem Michael addition of α,α-dicyanomethylidenecarbazoles with ß-nitrostyrenes afforded multifunctional benzo[a]carbazoles [BCs] and benzodihydro[a]carbazoles [BDHCs] in good yields. In addition, the direct multicomponent transformation of α,α-dicyanomethylidenecarbazoles, acenaphthenequinone and malononitrile results in the formation of unreported imino and amino functionalized spiro[acenaphthylene-8',4-benzo[a]carbazole] hybrids via amine-controlled divergent reactions. The spiro products were also obtained in good yields. The structures of the synthesized cycloadducts were confirmed by elemental analysis, spectral data (FT-IR, 1H, 13C NMR and HRMS) and by single-crystal X-ray diffraction studies.The application of this divergent tandem Michael addition protocol is beneficial from the viewpoint of the diversity-oriented one-pot synthesis of benzo[a]carbazole derivatives from simple starting materials.

Synthesis and characterization of carbazole derivatives and their antimicrobial studies.

The reaction of 1-oxo-1,2,3,4-tetrahydrocarbazoles (1a-e) with paraformaldehyde and ethylenediamine yielded N,N'-bis(1,2,3,4-tetrahydrocarbazol-1-ylidene)ethane-1,2-diamines (2a-e). Here, like in another similar attempt of replacing ethylenediamine by ethanolamine, ended up in formation of 2-{[1-(2-(2-aminoethoxy)ethylimino)-1,2,3,4-tetrahydrocarbazol-2-yl-methyl]amino}ethanols (3a-e). These products were characterized by IR, (1)H NMR, mass spectra and by elemental analysis. All end products (2a-e, 3a-e) were screened for antibacterial and antifungal activities. The compounds having substituents at C-6 position were found to exhibit pronounced antimicrobial activities.

Syntheses and characterisation of N,N'-biscarbazolyl azine and N,N'-carbazolyl hydrazine derivatives and their antimicrobial studies.

Reaction of 1-oxo-1,2,3,4-tetrahydrocarbazoles 1a-e with hydrazine hydrate in absolute ethanol afforded N,N'-bis-carbazolylazine derivatives 2a-e. Treatment of compounds 1a-e with hydroxylamine hydrochloride in ethanol with a catalytic amount of pyridine resulted in the formation of 1-hydroxyimino-1,2,3,4-tetrahydrocarbazoles 3a-e. Reduction of 3 with hydrazine hydrate in the presence of palladized carbon afforded N,N'-carbazolyl hydrazine derivatives 4a-e. The newly formed compounds were characterized by IR, 1H NMR, mass spectra and by elemental analysis. All compounds proved to have great potentialities as antibacterial and antifungal agents due to the presence of the azine or the hydrazine group. Particularly, the chloro substituted derivatives 2e and 4e showed excellent antibacterial and antifungal activity.

A one pot synthesis and evaluation of 13-oxo-quino[3,4-b]carbazol-N-oxides as antimicrobial agents.

1-Oxo-1,2,3,4-tetrahydrocarbazoles (1a-e) upon mixed aldol condensation with o-nitrobenzaldehyde (2) yielded 13-oxo-quino[3,4-b]carbazol-N-oxides (3a-e). All the prepared compounds were characterized by elemental and spectral analysis. A plausible mechanism for the formation of the final products is proposed. The title compounds proved to have great potentialities as antibacterial and antifungal agents due to the presence of the N-oxide group. Particularly, the chloro substituted derivative, 3d, showed excellent antimicrobial activity.