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Our research centers on structural, biological, and electronic properties of N-heterocyclic carbene salts and their silver acetate-based complexes. After theoretical calculations, compounds were synthesized. In the DFT studies, functional of B3LYP was used with the basis set of 6-31++G and LanL2DZ for salts and complexes, respectively. The most stable structures were calculated and non-covalent interactions evaluated. Electronic parameters were checked while calculating their HOMO and LUMO energies so that their biological potential can be evaluated. Density of states were studied to check the electronic densities. Among all compounds, 3 was considered the best with energy gap of 0.121 eV. As all eight compounds have very reasonable HOMO-LUMO energy gaps they were considered feasible to synthesize and have strong biological potentials. Compounds were characterized by FT-IR and NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Needle-shaped Mn-Zn bimetallic nanoparticles were prepared using wet chemical synthesis through hydrothermal method. Mn-Zn obtained product was analysed by scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). SEM and TEM analyses provide information regarding morphology of synthesised product. Results revealed Mn-Zn product is obtained as needle-shaped particles with thin and pointed edges. The synthesised bimetallic product was subjected to XRD analysis for composition and structural analysis. XRD results confirm the crystalline nature of product and further revealed lattice parameters and diffraction plane values. Bimetallic nanoparticles having unique properties are emerging materials in variety of applications because of synergistic effect. Photocatalytic and thermal catalytic degradation of Acid green 25 in aqueous media was catalysed in the presence of synthesised Mn-Zn as catalyst. Effect of parameters such as catalyst dose and H2O2 concentration on rate of degradation is also investigated. Mn-Zn showed more than 93% degradation at optimised conditions. Thermodynamic and kinetic evaluation of degradation is also discussed. Mn-Zn nanoneedles are further used as fuel additives to investigate physical and combustion properties of modified fuel. Efficiency of modified fuel is checked by studying fuel parameters at various Mn-Zn dosage. [ABSTRACT FROM AUTHOR]

Surface enhanced Raman spectroscopy (SERS) was used to determine the biochemical changes induced during the antibacterial activity of the in house synthesized imidazole derivatives in comparison to the commercially available pharmaceutical tinidazole. The antibacterial activity was assessed against Bacillus subtilis using various concentrations of antibacterial agents for this purpose. SERS detected significant changes in the bacterial cells following the application of both drugs, confirming the potential of this approach for analyzing the antibacterial activities of drug candidates. The SERS spectral features changed consistently with the increased antibiotic concentration at 548, 713, 730, 807, 858, 951, 958, 1004, 1028, 1110, 1128, 1242, 1280, 1320, 1398, 1418, 1453, 1567, and 1590 cm−1. Principal component analysis (PCA) and partial least squares–discriminant analysis (PLS-DA) were demonstrated to be useful for comparing the antibacterial actions of these imidazole derivatives. The sensitivity and specificity of this model were 97% and 95.7% respectively. [ABSTRACT FROM AUTHOR]

The synthesis of five selenium complexes bearing imidazole-based N-heterocyclic carbene ligands (Se-NHC) are reported. The adducts were characterized by elemental and spectroscopic analysis (FTIR, 1H and 13C NMR). Single-crystal XRD confirmed the structures of two Se-NHC adducts, VIII and XI. Zone of inhibition (ZOI) values of Se-NHC complexes were evaluated towards two bacterial (Bacillus thuringiensis and Escherichia coli) and one fungal strain (Candida albicans). The most active tested compound was XI with inhibition value of 24.1 ± 0.1 mm against E. coli, and it showed higher activity than Tetracycline (reference drug). Similarly, XI exhibited good inhibition potential against C. albicans (26.5 ± 0.2 mm). The hemolytic assay demonstrated that the tested compounds (VIII-XII) are non-toxic to healthy human blood; however, thrombolysis indicated that VIII-XII could be used as potential thrombolytic agents. It is concluded that Se-NHC carbene adducts having more aromatic rings at terminal nitrogens of imidazole are more effective than other tested compounds. Se-NHC compounds have more efficacy against bacterial strains than fungal strain. [ABSTRACT FROM AUTHOR]

Gold is an inert coinage metal forming stable coordination compounds with various ligands specifically N-heterocyclic carbenes (NHCs). NHCs react with aurate salts as well as other inorganic salts of gold to form stable gold complexes. Gold complexes have been reported to have various applications in different fields such as biological, bio-chemical, luminescence, molecular recognition, optical switches, electronics and catalysis. In the current review, synthesis of gold complexes involves bonding through different linkages like "C, P, S, NC, OC, NS, PC, PS and SC" elements. The commonly used solvents for the synthesis of gold complexes are dichloromethane, THF, DMF, etc. These complexes were mostly reported at temperatures from −40 to 120 °C with continuous stirring, according to the nature of ligands. An overview on techniques in synthesis of gold complexes through various routes has been compiled. [ABSTRACT FROM AUTHOR]

The study was designed to synthesize bromide-bridged mercury(II) symmetric and non-symmetric N-heterocyclic carbene complexes. The preparation of benzimidazolium salts (4–6) was accomplished by symmetrical and non-symmetrical substitution on benzimidazole. The salts were subjected to an in-situ process for metallation to get [Hg(II)-NHC] complexes [(HgBr-NHC)(µ2Br)2] (7–9) by reacting benzimidazolium salts (4–6) with mercury(II) acetate at room temperature. Compounds were characterized by elemental analyses, FT-IR and NMR spectroscopy. Single crystals of 7 and 8 were analyzed by X-ray crystallographic technique which showed tetrahedral dinuclear complexes with two bridging bromides. An attempt to explore the feasibility of redox transmetallation approach (RTM) for synthesis of ytterbium complexes was also carried out by reacting 7–9 with ytterbium powder under inert atmosphere. The products were metallic mercury, benzimidazolium salts, and ytterbium bromide instead of ytterbium complexes. [ABSTRACT FROM AUTHOR]

Four new bis-imidazolium salts 3–6 and their di- and polynuclear silver(I)–N-heterocyclic carbene (Ag(I)–NHC) complexes 7–10 were synthesized and characterized by using various analytical techniques. Single-crystal studies of 8 revealed a dinuclear structure whereas that of 9 revealed an interesting polynuclear structure. The quasi-reversibility of redox events in electrochemical study of 9 indicated that reduction produces unstable decomposed species and oxidation may be ascribed to these decomposed species. All the compounds were studied for their in vitro anticancer study against human breast cancer (MDA-MB-231) and colon cancer (HCT-116) cells. The study revealed that Ag(I)–NHC complexes are comparatively more potent than NHC precursors (salts). MDA-MB-231 cells appeared more sensitive to complexes than HCT-116 cells while reverse is the case for NHC salts. [ABSTRACT FROM AUTHOR]

Caffeic acid (CA) is a well-known natural compound used for both health supplement and metabolic diseases. In the present study, single, easy, and quick isolation procedure of caffeic acid was described from rosmarinic acid. A quick crystal formation also was described for highly hygroscopic CA which was spontaneous and stable with lower hygroscopic nature. In addition, the produced crystal CA was highly stable and showed neuroprotective activity with <6 μg/ml in R28 cell line and cytotoxic activity with >100 μg/ml in U87 MG which revealed its dual biological effect for the treatment of Alzheimer's disease and cancer, respectively. [ABSTRACT FROM AUTHOR]

The proligands of the series tetramethylenebis(N-n-alkylbenzimidazolium bromide) (wheren = 3–10) (1–8) asN-heterocyclic carbene (NHC) precursors have been prepared by reacting the initially synthesizedN-n-alkyl benzimidazole with 1,4-dibromobutane in 2 : 1 M ratio. A reaction of Ag2O with1–8resulted in the formation of Ag(I) complexes tetramethylenebis{(N-n-alkylylbenzimidazol-2-ylidene)silver(I)hexafluorophosphate} (9–16), respectively. All the synthesized compounds were characterized by FT-IR,1H NMR,13C NMR, atomic absorption and elemental analysis. Single-crystal X-ray diffraction study on tetramethylenebis{(N-n-octylbenzimidazol-2-ylidene)silver(I)hexafluorophosphate} (14) has revealed that the complex exists as a dinuclear compound. All compounds were assessed for their antiproliferation test on human colorectal cancer cell line (HCT 116). Interestingly, increasing then-alkyl chain length fromn = 3 to 10 of the proligands and their respective complexes showed trends in increased cytotoxicity against human colon cancer cell line. Cytotoxicity data showed that tetramethylene linked bis-benzimidazolium salts and their respective dinuclear Ag(I)–NHC complexes can be useful therapeutic agents against colon cancer. [ABSTRACT FROM PUBLISHER]

Thiosemicarbazones are an important class of compounds having significant biological properties. These compounds are used as stable ligands for the synthesis of coordination compounds of biological worth. The current study describes syntheses of four new N(3)-ethyl thiosemicarbazone derivatives and their in vitro anticancer testing. The purpose of the study was to observe the effect of various subtitutions at the aromatic ring against the growth of cancerous cell. The synthesized compounds were characterized by NMR (1H and13C) spectroscopy and the molecular structures of each of the compounds were determined using single crystal X-ray crystallographic technique. Interestingly, compound4appeared to have two crystallographically different units (A and B), having slightly different bond lengths and angles compared to each other. All the compounds were tested for their in vitro anticancer properties against human colon cancer (HCT 116) and breast cancer (MCF-7) cell lines. The compounds (1and2), having halide (Cl and Br) substitutions, showed significant activity compared to those having ethoxy and allyl substitutions (3and4), indicating the possible involvement of halides against cancerous cells. [ABSTRACT FROM PUBLISHER]

The current study reports the synthesis of a curcumin–silver(I) complex and its preliminary tests against four bacterial strains viz.Staphylococcus aureus,Escherichia coli,Bacillus subtilis, andBacillus cereususing agar well diffusion method. The results were compared with curcumin by testing it in parallel with the sample. Curcumin showed zones of inhibition against all tested strains of bacteria. Among all bacterial strains,S. aureuswas the most sensitive to curcumin with zone of inhibition of 12.2 mm. However, the curcumin–Ag(I) complex did not show the expected enhanced activity against all bacteria. This is perhaps due to the replacement of curcumin phenolic protons by silver ions which might have suppressed the antibacterial property of curcumin. The current research findings suggest that while synthesizing curcumin–metal complexes, the phenolic heads may either be left unaltered or need to be replaced by better substituents than hydroxy groups. Based on the current findings, biologically enhanced models have been provided as future recommendations. [ABSTRACT FROM PUBLISHER]

Cancer cases are alarmingly increasing worldwide, and newer chemotherapeutic agents are needed. Recent analogs ofcisplatin (carboplatin, lobaplatin, nedaplatin and oxaliplatin) and their marketing as advanced chemotherapeutic drugs have furthered the interest in metal-based anti-cancer drugs. In the current study, two new polymeric organotin(IV) carboxylate complexes (1and2) have been synthesized and characterized. Spectroscopic studies showed that coordination took place via carboxylates. Furthermore, X-ray crystallographic study on1indicated that it possesses a monomeric structure and exists in polymeric formation due to additional Sn–N coordination, assigning seven coordinations to each metal ion. Both the complexes were tested against three cancerous (human colon cancer, HCT 116; breast cancer, MCF-7; and leukemia, K562) and one non-cancerous (3T3-L1) cell lines. Complex1showed exceptional cytotoxicity against cancerous cell lines (IC50 = 1.0 μM for HCT 116; 258.7 nM for MCF-7; and 46.7 nM K562) and remained comparatively non-toxic against normal cells (IC50 = 37.0 μM). This shows that both complexes have selective cytotoxicity against cancer cells. [ABSTRACT FROM PUBLISHER]

The synthesis, spectral (FT-IR and NMR), and structural studies of 1,1?-methylene linked 3,3?-2-cyanobenzyl bis-imidazolium salt (L1) and respective dinuclear Ag(I)-NHC complex (C1) are reported. The structures of both compounds were established through single-crystal X-ray diffraction.C1has a short Ag–Ag separation of 3.16?Å. BothL1andC1were tested for potential against leukemia (k562) cell line. For comparison,para-xylyl linked bis-benzimidazolium salts (L2–L4) and their dinuclear Ag(I)-NHC complexes (C2–C4) were synthesized and tested against the same cell line (K562). The IC50values proved thatL2–L4andC2–C4are many fold more active thanL1andC1. The mechanism of action and structure activity relationship are discussed.In vivooral acute toxicity study (sighting study) was carried out which depicts that 2000 mg/kg dose of selected compounds is an appropriate and safe dose for conducting main study on animals. [ABSTRACT FROM AUTHOR]

This manuscript describes synthesis, spectral (FT-IR and NMR), and structural studies of a newpara-xylyl linkedbis-imidazolium salt (1) and the dinuclear Ag(I)–N-heterocyclic carbene complex (2). Both1and2were tested for their potential against human colon cancer (HCT 116) and breast cancer (MCF-7) cell lines. According to cell viability measurements using MTT assay, the test compounds showed dose-dependent cytotoxic activities against both cell lines. The complex displayed significant activity (IC50 = 20.9 μM for HCT 116 and 2.4 μM for MCF-7) compared to their respective imidazolium salt (IC50 > 200 μM for HCT 116 and  = 137 μM for MCF-7). The photomicrographs of the cells treated with2revealed that the cytotoxic efficacy of2is mainly by deposition of silver in the cytoplasm of the affected cells since clear signs of black silver deposits in the cytoplasm of the affected cells were observed. [ABSTRACT FROM AUTHOR]

AbstractThe silver organometallic compounds favorably target DNA in cancerous cells and stop their growth by inhibiting DNA replication. Specific properties of these compounds help in their action as drugs and different changes occur in the structure of DNA. In-depth study of the binding mechanism of drugs is of potential use for novel drug synthesis. Surface-enhanced Raman spectroscopy (SERS) coupled with multivariate data analysis was employed to probe the interaction of silver N-heterocyclic carbene complex (drug) with DNA. In this study, silver N-heterocyclic carbene complex was synthesized and various concentrations were exposed to known concentrations of DNA. Silver nanoparticles were used for enhancement of Raman signals, which enabled sensitive detection and characterization of molecular changes occurring during binding process. Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were applied to extract meaningful information from the spectral data. Changes in intensity and position of significant SERS signals were noted, which gave an indication of the bonding of the drug with DNA. The results reveal the strong intercalative binding of drug with nitrogenous bases of DNA. PCA and PLS-DA provide evidence for successful DNA-drug interaction. [ABSTRACT FROM AUTHOR]