A new Cu(II) complex, [Cu(L)(H2O)]ClO4, is synthesized, using tridentate N,N,O-donor Schiff base ligand 3,5dibromosalicylideneaminoguanidene, derived from aminoguanidine with 3,5-dibromosalicylaldehyde. The single crystal X-ray structure of the Cu(II) complex, crystallizing as [Cu(L)(H2O)]& sdot;0.5Cl & sdot;0.5ClO4, reveals Cu(II) adopts a square planar geometry. DFT calculations are used to understand the electronic structure of the ligand and the Cu(II) complex, and, TD-DFT calculations are performed to explain the nature of the transitions observed in their UV-Vis spectra. The complex binds very strongly to calf thymus DNA, with a binding constant of the order of 107 M- 1. Docking studies of the complex with calf thymus B-DNA sequences suggest that the complex is favorably aligned within the DNA structure, enabling the formation of hydrogen bonds and hydrophobic interactions with DNA bases, which contribute to overall stability, and the binding affinity was calculated to be -8.03 kcal mol-1. The complex is also capable of selective detection of histidine (His), in presence of other alpha-amino acids, at pH 7.4, by fluorescent turn-on method. The binding constant of the complex with histidine is 1.864 & times; 1013 M- 2 and L.O.D. is 1.95 pound 10- 8 M. The pH and temperature dependence of the sensing is also studied. The complex also binds to the protein, bovine serum albumin (BSA), with a binding constant of 4.52 & times;107 M-1, having binding site number of 1.48. The use of the ligand 3,5-dibromosalicylideneaminoguanidene for fluorometric sensing of Cu(II) is also reported.

The current study reports the electrocatalytic water oxidation by mononuclear bis-terpyridine Co(ii) complexes of general formula [CoL1-42]X2 (where L1 = 4 '-phenyl-2,2 ':6 ',2 ''-terpyridine, L2 = 4 '-(3,4-dimethoxyphenyl)-2,2 ':6 ',2 ''-terpyridine, L3 = 4 '-(3,4,5-trimethoxyphenyl)-2,2 ':6 ',2 ''-terpyridine, L4 = 4 '-(4-fluorophenyl)-2,2 ':6 ',2 ''-terpyridine, and X = ClO4-/Cl-). All the complexes have been fully characterized by single-crystal X-ray diffraction and mass spectroscopy, which show the CoN6 core structure in all the complexes. The complexes exhibit moderate to good electrocatalytic activity at pH 13.5. During the water oxidation study, an electrocatalytic wave in cyclic voltammetry appears near the Co(IV/III) couple in all four complexes (1-4). The electrocatalytic water oxidation occurs at an onset potential of 0.80 V, 0.81 V, 0.72 V, and 0.85 V vs. NHE for 1, 2, 3, and 4, respectively. The efficiency of the catalysts has been found to depend on the electron-withdrawing and -donating capacity of the substituents in the ligand scaffold. An electron-donating -OMe group in the terpyridine results in the maximum rate, while the electron-withdrawing -F group displays the lowest rate of the water oxidation reaction. Determination of the TOF values by both the peak current method (TOF1,2,3,4 = 10 s-1, 16 s-1, 40 s-1, 1 s-1, respectively) and FOWA (TOF1,2,3,4 = 22 s-1, 34 s-1, 194 s-1, 2 s-1) method follows the same trend. The faradaic efficiency of the complexes has been found to be 61%, 64%, 68%, and 35% for complexes 1, 2, 3, and 4, respectively. The TON calculated for complexes 1, 2, 3, and 4 have been found to be 11, 13, 18, and 5, respectively. The mechanism of water oxidation has been proposed based on mass spectral data of the electrochemically oxidised species and DFT calculations. All the molecules act as active OEC (oxygen-evolving complexes) photochemically with visible light in the presence of [Ru(bpy)3]Cl2 as photosensitizer and Na2S2O8 as electron acceptor.

A dinuclear copper complex with the formula Cu 2 L 2 (where L = [3-((pyridin-2-ylmethyl)carbamoyl)isonicotinic acid]) was synthesized and characterized by single-crystal XRD and mass spectrometry.

A dinuclear copper complex (1) with the formula Cu2L2 (where L = [3-((pyridin-2-ylmethyl)carbamoyl)isonicotinic acid]) was synthesized and characterized by single-crystal XRD and mass spectrometry. The complex showed a high order of electrocatalytic hydrogen evolution reaction (HER) and carbon dioxide reduction reaction (CO2RR) activity in acidic media, along with a moderate oxygen evolution reaction (OER) activity in the pH range of 7 to 13.5. The efficiency of 1 for the HER was calculated as follows: TOF = 1679 s-1, TON = 586 and F.E. = 83% in 56 equivalents of perchloric acid. For the CO2RR, a TOF value of 4 h-1, a TON of 18 and an F.E. of 92% were observed, with a percentage selectivity of ∼99.99% for CO2 to (COOH)2. The best water oxidation activity was accomplished at pH 13.5 with the following electroanalytical efficacy parameters: TOF = 9 s-1 (peak current method), TOFFOWA = 31 s-1, TON = 66 and F.E. = 84%. The high stability of the molecular catalyst was analyzed through CV, FESEM, EDX and DLS.

Two high spin Fe(III) complexes, [Fe(L1)2]Cl & sdot; H2O (1) and [Fe(L2)2]Cl & sdot; 4H2O & sdot; 0.5MeOH (2), of Schiff base ligands of aminoguanidine with salicylaldehyde and pyridoxal (isolated as the hydrochloride salts L1H2+Cl- and L2H32+Cl-2 respectively) are reported. X-ray crystal structure of both the complexes along with their spectroscopic and variable temperature magnetic properties are also investigated. It is found that complex 2 shows stronger zero field splitting (D=9.5 cm-1) than complex 1 (D=5.5 cm-1), probably due to greater distortion of the Fe(III) coordination polyhedron in complex 2. TD-DFT calculations are used to assign the electronic spectra of the complexes. Both the ligands show fluorescence at 450-460 nm with lifetime of nanosecond order and quantum yield of 0.04-0.07 at room temperature. Both the Fe(III) complexes are found to efficiently catalyze the aerial oxidation of DTBC to DTBQ with the turn over numbers 100-155 h-1, which is among the highest for mononuclear Fe(III) complexes. The complexes also act as very good fluorometric sensor for S2-, and the limit of detection (LOD) is in the octa-molar region. The pH and temperature dependences of the sensing are also investigated.

This study focuses on the synthesis, characterisation, and the study of absorption, emission and electrochemical properties of Co(II) bis-terpyridine complexes with varying substituents at the 4'-position of the central pyridine ring of terpyridine moiety. The study shows tuning of light harvesting range by modifying the substituent e.g. furyl, phenylethylene and 3,4-dimethoxyphenyl moieties. Single Crystal XRD data of bis-(4'-furyl)terpyridine) cobalt(II) and bis-(4'-(3,4-dimethoxyphenyl)terpyridine)cobalt(II) have been reported. The bis-(4'-phenylethyleneterpyridine)cobalt(II) complex showed room temperature emission. The electrochemical properties of the complexes were studied with cyclic voltammetry, which reveals reversible CoIII/II redox feature. Room temperature EPR spectrum of powdered samples of all the complexes are recorded and simulated which indicates a low-spin Co(II) centre. Theoretical structure optimisation of all the complexes has been performed at the B3LYP level using 6-31G(d,p) for ligands and LANL2DZ basis sets for metal. Theoretical absorption is calculated and the underlying electronic transitions for the observed absorption peaks were indicated.

This work presents an electro-catalytic and photochemical study of the Co(ii) complexes [Co(L1)2](ClO4)2 (1), [Co(L2)2]Cl2 (2), and [Co(L3)2](ClO4)2 (3), where L1 = 2,6-bis(1H-benzo[d]imidazole-2-yl)pyridine, L2 = 2,6-bis(4,5-dimethyl-1H-benzo[d]imidazole-2-yl)pyridine, and L3 = 2,6-bis(4-fluoro-1H-benzo[d]imidazole-2-yl)pyridine. These complexes were investigated as catalysts for hydrogen production from acids. In electro-catalytic tests, the complexes were evaluated in a non-aqueous solvent with moderately strong trifluoroacetic acid (TFA) as the substrate, showing catalytic wave onset at -0.93 V, -1.13 V, and -1.06 V vs. Fc+/Fc for complexes 1, 2, and 3, respectively. The complexes demonstrated turnover frequencies of 26.42 s-1, 1.56 s-1, and 1.26 s-1 at a 14 : 1 acid-to-catalyst ratio, with hydrogen production detected by gas chromatography. Zinc complexes (4-6) with the same ligands were also screened for electrocatalytic hydrogen evolution to identify the active site for catalysis. The cobalt complexes were also tested for photochemical proton reduction in water at pH 7, using [Ru(bpy)3]2+ as the photosensitizer and ascorbic acid as the sacrificial electron donor. The cobalt complexes thus demonstrate effectiveness as catalysts for both electro-catalytic and photo-catalytic proton reduction in non-aqueous and aqueous solutions.

The main objective of the present study was to investigate the influence of graphene nanoplatelets (GnPs), Titanium dioxide (TiO2), and its hybrid filler on the mechanical, thermal, and morphological characteristics of polypropylene (PP) based hybrid composites for structural applications. The PP-based hybrid composites were prepared using a twin-screw extruder for different filler compositions and then molded into tensile specimens with a mini-jet injection molding setup. Tensile, thermal, and morphological analyses were performed to determine the hybrid capability of the PP-based composites. The results showed that the values of tensile modulus and tensile yield strength show significant improvement at about ∼24% and ∼17%, while the values of elongation at break show a slightly decreasing trend for the hybrid composites compared to PP composites. The thermal stability analysis shows that the higher the hybrid filler content, the higher the temperature. Further, the SEM micrographs for the hybrid fillers show good dispersion onto the PP matrix, which may increase the interfacial adhesion between PP and fillers, thus enhancing the mechanical and thermal properties of PP-based hybrid composites.

Biobutanol, a promising biofuel with superior properties compared to ethanol, has garnered significant attention as an alternative to traditional fossil fuels. In the present study pretreatment of rice husk with deep euectic solvent using choline chloride and urea (ChCl/U) was investigated for the production of biobutanol. DES pretreatment and enzymatic hydrolysis yielded 30 ± 0.54 mg/ml of reducing sugar. This study also investigates the synergistic potential of co-culturing Bacillus cereus and Clostridium acetobutylicum for enhanced biobutanol production. B. cereus, known for its robust metabolism and extracellular enzyme secretion, is paired with C. acetobutylicum, a proficient butanol producer. The coculture produced 4.7 ± 0.69 g/l of biobutanol. The co-culture strategy aims to capitalize on the complementary metabolic capabilities of the two strains, facilitating improved substrate utilization and butanol production.

Coherency of nature has always inspired human to develop, produce and innovate by imitating it. Photosynthesis is amongst the most efficient bio-chemical reaction nature exudes and thus produces high-end products important for the sustenance of life. Four electron oxidation of water to oxygen is one of the toughest reactions in natural system that is easily effectuated by Photosystem II (PS-II). The remarkable endothermic nature of this reaction has made the water oxidation bottleneck of artificial photosynthetic energy production. Excellent performance of noble metals e.g. Ruthenium is overshadowed by its expensive nature. A dire need of non noble metal, particularly a 3d metal catalyst is essential. With the variable oxidation states, 3d metals posses the potential to peruse this novel task. In this review we will sum up and analyze the development in the field of water oxidation catalysts made from the 3d transition metal complexes highlighting their catalytic rates and mechanism. As the theme of the research is based on the natural process, a discussion is also made on the catalytic centre of the natural process (photosynthesis).

Biobutanol, a promising biofuel with superior properties compared to ethanol, has garnered significant attention as an alternative to traditional fossil fuels. Recently, lignocellulosic biomasses (LCB) represent promising sustainable feedstock options for biorefineries aiming to produce renewable biofuels and biochemicals. Deep eutectic solvents (DES) are now recognized as an effective pretreatment method for lignocellulosic biomass, as they improve cellulose accessibility for subsequent hydrolysis and enhance fermentable sugar yield. DES has several benefits over conventional solvents, such as low toxicity and biodegradability which makes them appropriate for usage with a variety of lignocellulosic biomass. Therefore, in the present study, pretreatment of rice husk with deep eutectic solvent using choline chloride and urea (ChCl/U) was investigated for the production of biobutanol. This study also investigates the synergistic potential of coculturing Bacillus cereus and Clostridium acetobutylicum for enhanced biobutanol production. B. cereus, known for its robust metabolism and extracellular enzyme secretion, is paired with C. acetobutylicum, a proficient butanol producer. The coculture produced 4.7 ± 0.7 g/L of biobutanol. The coculture strategy aims to capitalize on the complementary metabolic capabilities of the two strains, facilitating improved substrate utilization and butanol production.

The main objective of the present study was to investigate the influence of graphene nanoplatelets (GnPs), Titanium dioxide (TiO 2 ), and its hybrid filler on the mechanical, thermal, and morphological characteristics of polypropylene (PP) based hybrid composites for structural applications. The PP-based hybrid composites were prepared using a twin-screw extruder for different filler compositions and then molded into tensile specimens with a mini-jet injection molding setup. Tensile, thermal, and morphological analyses were performed to determine the hybrid capability of the PP-based composites. The results showed that the values of tensile modulus and tensile yield strength show significant improvement at about ∼24% and ∼17%, while the values of elongation at break show a slightly decreasing trend for the hybrid composites compared to PP composites. The thermal stability analysis shows that the higher the hybrid filler content, the higher the temperature. Further, the SEM micrographs for the hybrid fillers show good dispersion onto the PP matrix, which may increase the interfacial adhesion between PP and fillers, thus enhancing the mechanical and thermal properties of PP-based hybrid composites. Keywords Hybrid nanocomposite , polypropylene , graphene nanoplatelets (GNPS) , titanium dioxide TiO , mechanical properties

The present work describes electrocatalytic water oxidation of three monomeric copper complexes [Cu-II(L1)] (1), [Cu-II(L2)(H2O)] (2), and [Cu-II(L3)] (3) with bis-amide tetradentate ligands: L1 = N,N '-(1,2-phenylene)dipicolinamide, L2 = N,N '-(4,5-dimethyl-1,2-phenylene)bis(pyrazine-2-carboxamide), L3 = N,N '-(1,2-phenylene)bis(pyrazine-2-carboxamide), for the production of molecular oxygen by the oxidation of water at pH 13.0. Ligands and all complexes have been synthesized and characterized by single crystal XRD, analytical, and spectroscopic techniques. X-ray crystallographic data show that the ligand coordinates to copper in a dianionic fashion through deprotonation of two -NH protons. Cyclic voltammetry study shows a reversible copper-centered redox couple with one ligand-based oxidation event. The electrocatalytic water oxidation occurs at an onset potential of 1.16 (overpotential, eta approximate to 697 mV), 1.2 (eta approximate to 737 mV), and 1.23 V (eta approximate to 767 mV) for 1, 2, and 3 respectively. A systematic variation of the ligand scaffold has been found to display a profound effect on the rate of electrocatalytic oxygen evolution. The results of the theoretical (density functional theory) studies show the stepwise ligand-centered oxidation process and the formation of the O-O bond during water oxidation passes through the water nucleophilic attack for all the copper complexes. At pH = 13, the turnover frequencies have been experimentally obtained as 88, 1462, and 10 s(-1) (peak current measurements) for complexes 1, 2, and 3, respectively. Production of oxygen gas during controlled potential electrolysis was detected by gas chromatography.

A pentadentate diamide ligand, N,N '-di(pyridine-2-yl)pyridine-2,6-dicarboxamide (L1H2) and its tetranuclear Cu(II) complex [Cu4(L1)2(mu 3-OH)2(H2O)3(ClO4)](ClO4) & sdot; H2O are reported. X-ray crystal structure of the complex reveals that it has an open-book type architecture. Two central copper atoms are connected to each other by two hydroxo bridges. Each of these two hydroxo bridges also connects the two central copper atoms to one of the two terminal copper atoms. Variable temperature susceptibility measurements show that chi MT decreases with the temperature, indicating a strong antiferromagnetic behavior. With the help of DFT calculations the magnetic data was analyzed using the spin Hamiltonian H=-2 J1S3 & sdot; S4 -2 J2(S3 & sdot; S1+ S3 & sdot; S2+ S4 & sdot; S1+ S4 & sdot; S2)-2 J3S1 & sdot; S2 (where subscripts 1 and 2 refer to the terminal copper atoms and 3 and 4 refer to the central copper atoms). The best fit was obtained with 2 J1=-322 cm-1, 2 J2=+34.8 cm-1, 2 J3=-8.8 cm-1 and g=2.18, indicating a delta-type interaction between terminal copper atoms. The complex proves to be an avid binder of ct-DNA, with apparent binding constant (Kapp) value estimated as 1.536x107 M-1. In vitro experiments indicate that the Cu(II) complex reduced the proliferation of HCT116 cells among other cell lines. This reduction of cell proliferation may be attributed to the enhancement of intracellular ROS, along with modulation and disruption of cell cycle associated proteins. SKC conceptualized the project, arranged funding and involved in overall coordination among collaborators, analyzing the data, and writing the paper. AM was involved in doing the experimental work on synthesis of the compounds, carrying out analytical and spectroscopic measurements, collecting X-ray crystallographic data and DNA binding experiments. MS, SM and KDS were involved in study of anticancer activities of the complex. SS helped in refining X-ray structure of the complex. MC did the magnetic measurements and analysis whereas AF did the DFT calculations. A tetranuclear Cu(II) complex of a pentadentate ligand, containing pyridine2,6-diamide motif, is reported. The X-ray structure of the complex reveals that it has an open book type architecture. The magnetic property of the complex is explored by VT susceptibility measurements and DFT calculations. The complex shows strong antiproliferative activity against HCT116 cancer cells. Possible mechanism of anticancer activity is also discussed. image

As a product of photosynthesis, the storable chemical energy in the form of carbohydrates inspires the people engaged in renewable energy research to mimic the natural process. This may be the reduction of the proton or carbon dioxide to produced fuels e.g., hydrogen or CH4 and CH3OH or other chemical feed stocks e.g., HCOOH, CO32-. (COOH)2. This replication of the natural process is known as Artificial Photosynthesis. In either case water oxidation is mandatory. Herein, we discuss brief mechanism of photosynthesis, emphasizing the role of Water Oxidation Catalyst (WOC). Literature on Manganese based WOC is presented with their characteristic features.

Three monomeric ruthenium complexes with anionic ligands [Ru-II(L)(L-1)(DMSO)][ClO4] (1), [Ru-II(L)(L-2)(DMSO)] [PF6] (2), and [Ru-II(L)(L-3)(DMSO)][PF6] (3) [L = pyrazine carboxylate, L-1 = 2,6-bis(1H-benzo[d]imidazol-2-yl)pyridine, L-2 = 4,5-dmbimpy = 2,6-bis(5,6-dimethyl-1H-benzo[d]imidazol-2-yl)pyridine, L-3 = 4-Fbimpy = 2,6-bis(5-fluoro-1H-benzo[d]imidazol-2-yl)pyridine, DMSO = dimethyl sulfoxide] as electrocatalysts for water oxidation are reported herein. The single crystal X-ray structure of the complexes reveals the presence of a DMSO molecule, which is supposed to be the labile group undergoing water exchange under the experimental condition of electrocatalysis. Linear sweep voltammetry (LSV) and cyclic voltammetry (CV) study shows the appearance of the catalytic wave for water oxidation at Ru(iv/v) oxidation. LSV, CV, and bulk electrolysis technique has been used to study the redox properties of the complexes and their electrocatalytic activity. A systematic variation on the ligand scaffold has been found to display a profound effect on the rate of electrocatalytic oxygen evolution. Electrochemical and theoretical (density functional theory) studies support the O-O bond formation during water oxidation passes through water nucleophilic attack (WNA) for all the ruthenium complexes. At pH 1, the maximum turnover frequency (TOFmax) has been experimentally obtained as 17556.25 s(-1), 31648.41 s(-1), and 39.69 s(-1) for complexes 1, 2, and 3, respectively, from the foot of wave analysis (FOWA). The high value of TOFmax for complex 2 indicates its efficiency as an electrocatalyst for water oxidation in a homogeneous medium.

In this work, three titanium(IV) [TiIV(L1-3)2] (1-3) complexes have been reported using three different tridentate dibasic ONO donor hydrazone ligands, pyridine-4-carboxylic acid (3-ethoxy-2-hydroxybenzylidene)-hydrazide (H2L1), furan-2-carboxylic acid (3-ethoxy-2-hydroxybenzylidene)-hydrazide (H2L2), and thiophene-2-carboxylic acid (3-ethoxy-2-hydroxybenzylidene)-hydrazide (H2L3) tethered with heterocyclic moieties. Elemental analysis, FT-IR, UV-vis, NMR, HR-ESI-MS, and single-crystal X-ray analysis have been used to characterize H2L1-3 and 1-3. In solid structures of 1-3, two ligand molecules with N2O4 donor sets give distorted octahedral geometries to the metal center. The aqueous stability of 1-3 was investigated and well correlated to their perceived pharmacological results. During the investigation, all three complexes were found to be hydrolytically stable in a 90% DMSO-d6/10% D2O (v/v) medium up to 48 h. Furthermore, the interaction of 1-3 with bovine serum albumin (BSA) was tested using fluorescence and absorption techniques. The complexes showed static quenching with a biomolecular quenching constant of Kq ∼ 1013 proposing a high affinity of complexes for BSA. Finally, the anticancer potential of 1-3 was tested against HeLa, A549, and NIH-3T3 cell lines. Among all, 1 with an IC50 value of 11.6 ± 1.1 μM against HeLa cells was found to be the most cytotoxic in the series. Furthermore, it has been found that the compounds induce an apoptotic mode of cell death, which is confirmed by the live cell confocal microscopy and flow cytometry techniques.

The mucilaginous polysaccharide from Abroma augusta stem was examined for its physicochemical, thermal, and functional behavior and explored as a carrier for probiotic bacteria. Composed of glucose, galactose, rhamnose, galactouronic acid and fucose, Abroma augusta mucilage (AAM) exhibited shear thinning behavior (following power law equation) and gel like characteristic (showing higher G ' value than G '' value). AAM promoted the growth of probiotic strains with positive prebiotic scores of 0.5 +/- 0.06 and 0.51 +/- 0.05 for Lactobacillus aci-dophilus and Lactobacillus casei, respectively. Further, probiotic strains were embedded in the AAM matrix fol-lowed by freeze-drying with embedding efficiency of >95%. Viscoelastic properties were retained substantially in the rehydrated probiotic-embedded matrix. AAM could protect probiotic bacteria in simulated gastrointestinal conditions, at elevated (80 C-o, 20 min) and at low (4 C-o, 4 months) temperatures ensuring higher viabilities of embedded probiotic cells. Our findings established potential carrier capabilities of AAM polysaccharides for probiotic bacteria with thickening and prebiotic activity.