Green synthesis of MnO2 nanoparticles from Psidium guajava leaf extract: Morphological characterization, photocatalytic and DNA/BSA interaction studies.

In this work, a simple, efficient and eco-friendly green synthesis of manganese dioxide nanoparticles (MnO2NPs) by Psidium guajava leaf extract was described. Fourier-Transform infrared spectra results revealed that involvement of the plant extract functional groups in the formation of MnO2NPs. The UV-vis absorption spectra of the synthesized MnO2NPs exhibited absorption peaks at 374 nm, which were attributed to the band gap of the MnO2NPs. Crystal phase identification of the MnO2NPs were characterized by X-ray diffraction analysis and the formation of crystalline MnO2NPs have been confirmed. Furthermore, scanning electron microscopy analysis showed that the synthesized MnO2NPs have a spherical in shape. Interestingly, the prepared green synthesized MnO2NPs showed catalytic degradation activity for malachite green dye. Malachite green's photocatalytic degradation was detected spectrophotometrically in the wavelength range of 250-900 nm, and it was discovered to have a photodegradation efficiency of 75.5 % within 90 min when exposed to solar radiation. Green synthesized MnO2NPs are responsible for this higher activity. An interaction between synthesized NPs and biomolecules, including CT-DNA and BSA was also evaluated. The spectrophotometric and Fluoro spectroscopic analyses indicate a gradual reduction in peak intensities and shifts in wavelengths, indicating binding and affinity between the NPs and the biomolecules.

Spectroscopic and theoretical approach of DNA interaction and anticancer studies of bio-pharmaceutically active pyrimidine derived Cu(II) and Zn(II) complexes.

New metal(II) complexes (CuL2 and ZnL2) with pyrimidine appended Schiff base ligand (HL) were synthesized and characterized by diverse spectroscopic methods, reveals the proposed structure of metal(II) complexes possess square planar geometry. DNA interaction ability of isolated compounds was studied by UV-Visible, fluorescence, viscometric and electrochemical methods and the results showed that isolated compounds intercalated with calf thymus DNA (CT-DNA). In addition, anticancer activities of HL, CuL2, and ZnL2 have been evaluated by MTT assay, signifying moderate cytotoxic activity on selected cancer cell lines and less toxicity on NHDF normal cell line due to the specific targeting of pyrimidine analogues. Moreover, antioxidant activities of isolated compounds towards diverse free radicals have been studied by spectrophotometric methods. These results showed that CuL2 has better antioxidant ability than HL and ZnL2. Finally, antimicrobial activities of isolated compounds against selected antimicrobial pathogens exposed that CuL2 has better antimicrobial activity on E. coli and C. albicans than other antimicrobial pathogens. The DFT calculations have been done to get the optimized geometry of the ligand and the metal complexes. In order to get a broad understanding of the interactions of these synthesized metal complexes, a detailed molecular docking analysis is taken up.

Synthesis, spectral, DFT calculation, antimicrobial, antioxidant, DNA/BSA binding and molecular docking studies of bio-pharmacologically active pyrimidine appended Cu(II) and Zn(II) complexes.

A new pyrimidine derivative Schiff base (HL) [HL = 2-((4-amino-6-chloropyrimidin-2-ylimino)methyl)-4-nitrophenol] has been synthesized using 2,6-diamino-4-chloropyrimidine and 5-nitrosalicylaldehyde. Transition metal complexes of Cu(II) and Zn(II) complexes [CuL(OAc)] (1), [ZnL(OAc)] (2) are prepared with HL/metal(II) acetate with molar ratio of 1:1. The Schiff base (HL) and the complexes 1 and 2 are evaluated by UV-Visible, 1H-NMR, FT-IR, EI-MS and ESR spectral techniques. Complexes 1 and 2 are confirmed as square planar geometry. Electrochemical studies of the complexes 1 and 2 are used to analyse the quasi reversible process. Density Functional Theory (DFT) using the B3LYP/6-31++G(d,p) level basis set was used to get the optimised geometry and non-linear optical properties. The complexes 1 and 2 are good antimicrobial agents than Schiff base (HL). The interactions of the HL and complexes 1 and 2 with Calf Thymus (CT) DNA are investigated by electronic absorption methods and viscosity measurements. Various molecular spectroscopy techniques, such as UV absorption and fluorescence, were used to explore the mechanism of interaction between the BSA and the ligand HL and complexes 1 & 2 under physiological settings. Complexes 1 and 2 are act as potential antioxidants than free Schiff base (HL) by DPPH radical scavenging assay. Furthermore, the purpose of the molecular docking studies was to better understand how metal complexes interact with biomolecules (CT-DNA and BSA). From these biological analyses, complex 1 acts as good intercalator with CT DNA & BSA and potent antioxidant with DPPH radical than complex 2.Communicated by Ramaswamy H. Sarma.

Aggregation-induced emission enhancement (AIEE) of tetrarhenium(I) metallacycles and their application as luminescent sensors for nitroaromatics and antibiotics.

The self-assembly of tetrarhenium metallacycles [{Re(CO)3}2(µ-dhaq)(µ-N-N)]2 (3a, N-N = 1,3-bis(1-butylbenzimidazol-2-yl)benzene; 3b, N-N = 1,3-bis(1-octylbenzimidazol-2-yl)benzene), (H2-dhaq = 1,4-dihydroxy-9,10-anthraquinone) and [{Re(CO)3}2(µ-thaq)(µ-N-N)]2 (4, N-N = 1,3-bis(1-butylbenzimidazol-2-yl)benzene), (H2-thaq = 1,2,4-trihydroxy-9,10-anthraquinone) under solvothermal conditions is described. The metallacycles 3a,b and 4 underwent aggregation-induced emission enhancement (AIEE) in THF upon the incremental addition of water. TEM images revealed that metallacycle 3a in a 60% aqueous THF solution formed rectangular aggregates with a wide size distribution, while a 90% aqueous THF solution resulted in the formation of a mixture of nanorods and amorphous aggregates due to rapid and abrupt aggregation. UV-vis and emission spectral profiles supported the formation of nanoaggregates of metallacycles 3a,b and 4 upon the gradual addition of water to a THF solution containing metallacycles. Further studies indicated that these nanoaggregates were excellent probes for the sensitive and selective detection of nitro group containing picric acid (PA) derivatives as well as antibiotics.

Biologically active oxovanadium(IV) Schiff base metal complex: antibacterial, antioxidant, biomolecular interaction and molecular docking studies.

The oxovanadium(IV) Schiff base metal complex (ISNPV) have been synthesized as well as characterized by using micro analytical and traditional spectroscopic techniques. The spectral findings were utilized to validate the formation of ISNPV with structure exhibited square pyramidal geometry. The in vitro antibacterial activities of ISNPV were investigated to five different bacterial stains such as S. aureus, S. epidermidis, B. cereus, B. amyloliquefaciens and B. subtilis. The obtained result have suggested that the ISNPV has highest antibacterial activity against S. aureus than the other bacterial stains. The in vitro antioxidant activity like DPPH free radical scavenging assay method was studied by ISNPV in DMSO medium. Because it scavenges all free radicals, the ISNPV possesses higher antioxidant activity than the free ligand. UV-visible absorption and emission spectral techniques were used to investigate the binding of CT-DNA to the ISNPV. Both the spectral data indicate that the ISNPV binds the double helix structure of CT-DNA via an intercalation mode. Additionally, investigate the interactions of ISNPV with the protein molecules like BSA/HAS has been investigated using absorption and emission techniques. The absorption intensity of metal complex increases as well as the emission intensity of protein molecules ability decreases due to the binding nature of ISNPV with BSA/HSA protein molecules. The binding nature of ISNPV with bio molecules such as CT-DNA, BSA and HSA was also validated using molecular docking approach.

Bioactive platinum complex of ligand bearing pyrimidine skeleton: DNA/BSA binding, molecular docking, anticancer, antioxidant and antimicrobial activities.

A new octahedral platinum complex [PtLCl4] of Schiff base ligand containing pyrimidine and morpholine skeleton (where, L is 4,6-dichloropyrimidin-5-yl)methylene)-2-morpholinoethanamine) was isolated and characterized by elemental analysis, 1H-NMR, FTIR, UV-visible and ESI-MS techniques. DNA interaction of isolated compounds with calf thymus (CT-DNA) was explored by UV-vis absorption, fluorescence, cyclic voltametric and viscometric methods. The result shows that prepared compounds can interact with CT-DNA through electrostatic interactions. Bovine serum album (BSA) binding behavior of isolated compounds was also studied by UV-vis absorption and fluorescence techniques. Both the spectroscopic results suggest that the isolated ligand and its complex bind with BSA through static quenching. The optimized structure of ligand and platinum complex were achieved by the DFT calculations. Moreover, molecular docking of ligand and its complex were studied. These analysis results reveal that ligand has low binding affinity on DNA and BSA molecules in contrast to its complex. In vitro anticancer activity of isolated compounds toward normal cell line (NHDF) as well as cancer cell lines (MCF-7, HepG2, HeLa and A549) was studied by MTT assay. The results supports that isolated platinum complex can control the growth of cancer cells (MCF-7, 20.12 ± 1.00 µg/mL; HepG2, 32.2 ± 1.69 µg/mL; HeLa, 24.68 ± 1.29 µg/mL; A549, 23.46 ± 1.17 µg/mL) without inhibiting the normal cell line (NHDF, 109.26 ± 5.46 µg/mL). Antioxidant and antimicrobial activities of isolated compounds indicate that ligand and Pt complex are found to have good radical scavenging against four different free radicals and antimicrobial abilities on E. coli and C. albicans antimicrobial species. HighlightsPlatinum complex of Schiff base with pyrimidine and morpholine linkage was synthesized.Pt complex has better biomolecular interaction with DNA and BSA.Molecular docking of Pt complex with DNA and BSA has been studiedPt complex has good anticancer activities.Pt complex has better antioxidant and antimicrobial activities.

Selective anions mediated fluorescence "turn-on", aggregation induced emission (AIE) and lysozyme targeting properties of pyrene-naphthalene sulphonyl conjugate.

We have designed and synthesized a novel pyrene-naphthalene sulphonyl conjugate, 1-((1Z)-(4-((Z)-4-(pyrene-1-yl)methyleneamino)phenylsulfonyl)phenylimino)methyl)naphthalene-2-ol (PSN) through a facile two-step reactions. It was characterized by various spectral techniques. Fluorescence spectral studies showed that compound PSN featured fluorescence enhancement upon increasing the water content in THF. This can be attributed to the phenomena of aggregated induced emission (AIE), which is confirmed by SEM and AFM studies, due to the restriction of CHN isomerization of PSN. The anion sensing of PSN was examined with various anions. Among these anions, H2PO4- and F- ions were selectively sensing with a low detection limit of 3.52 × 10-7 M and 7.23 × 10-7 M, respectively, and an obvious color change from yellow to orange was observed by the naked eye. The mechanism of sensing involved the formation of hydrogen bonding interaction between O-H group of PSN and H2PO4-/ F- ions. The binding of PSN with LYZ was also examined by docking studies, which shows that H-bonding and hydrophobic interactions play crucial roles for the interaction of LYZ toward PSN.