Pyridine-2,6-Dicarboxylic Acid As a Facile and Highly Selective "Turn-Off" Fluorimetric Chemosensor for Detection of Cu (II) Ions in Aqueous Media.

Copper metal is third most abundant trace element in human body. Determination of Cu (II) ions is a burning topic in field of environment protection and food safety because of its significant impact on ecosystem. In this study, 2,6-pyridine dicarboxylic acid (PDA) has been explored as "turn-off" florescent probe for florescent detection of Cu (II) ions. This sensor showed highly selective complexing ability towards Cu (II) ions. Addition of aqueous solution of Cu (II) ions remarkably quenched the fluorescence intensity of PDA while, on contrary, there was no any prominent fluorescence quenching interference on addition of various metal ions. The binding mode of PDA and Cu (II) ions was determined as stoichiometry of 1:1 and it was further confirmed by single crystal XRD analysis. Mechanisms of static and dynamic quenching were confirmed by stern-volmer plot. Limit of detection (LOD) and limit of quantification (LOQ) for Cu (II) ions was calculated as 3.6 µM and 1.23 µM respectively, which is far below the acceptable value (31.5µM) according to the World Health Organization. The use of the sensor for detection of Cu (II) ions in real samples in aqueous media was also performed.

Cu-MOF loaded chitosan based freeze-dried highly porous dressings with anti-biofilm and pro-angiogenic activities accelerated Pseudomonas aeruginosa infected wounds healing in rats.

Metal-organic frameworks (MOFs)-based therapy opens a new area for antibiotic-drug free infections treatment. In the present study, chitosan membranes (CS) loaded with two concentrations of copper-MOF 10 mg/20 ml (Cu-MOF10/CS) & 20 mg/20 ml (Cu-MOF20/CS) were prepared by a simple lyophilization procedure. FTIR spectra of Cu-MOF10/CS and Cu-MOF20/CS dressings confirmed absence of any undesirable chemical changes after loading Cu-MOF. The SEM images of the synthesized materials (CS, Cu-MOF10/CS & Cu-MOF20/CS) showed interconnected porous structures. Cytocompatibility of the materials was confirmed by fibroblasts cells culturing and the materials were hemocompatible, with blood clotting index <5 %. Cu-MOF20/CS showed comparatively higher effective antibacterial activity against the tested strains; E. coli (149.2 %), P. aeruginosa (165 %) S. aureus (117.8 %) and MRSA (142 %) as compared to Amikacin, CS and Cu-MOF10/CS membranes. Similarly, Cu-MOF20/CS dressing significantly eradicated the biofilms; P. aeruginosa (37 %) and MRSA (52 %) respectively. In full thickness infected wound rat model, on day 23, Cu-MOF10/CS and Cu-MOF20/CS promoted wound healing up to 87.7 % and 82 % respectively. H&E staining of wounded tissues treated with Cu-MOF10/CS & Cu-MOF20/CS demonstrated enhanced neovascularization and re-epithelization along-with reduced inflammation, while trichrome staining exhibited increased collagen deposition. Overall, this study declares Cu-MOFs loaded chitosan dressings a multifunctional platform for the healing of infected wounds.

Recent advances in the fluorimetric and colorimetric detection of cobalt ions.

Cobalt is an essential metal to maintain several functions in the human body and is present in functional materials for numerous applications. Thus, to monitor these functions, it is necessary to develop suitable probes for the detection of cobalt. Presently, researchers are focused on designing different chemosensors for the qualitative and quantitative detection of the metal ions. Among the numerous methods devised for the identification of cobalt ions, colorimetric and fluorimetric techniques are considered the best choice due to their user-friendly nature, sensitivity, accuracy, linearity and robustness. In these techniques, the interaction of the analyte with the chemosensor leads to structural changes in the molecule, causing the emission and excitation intensities (bathochromic, hyperchromic, hypochromic, and hypsochromic) to change with a change in the concentration of the analyte. In this review, the recent advancements in the fluorimetric and colorimetric detection of cobalt ions are systematically summarized, and it is concluded that the development of chemosensors having distinctive colour changes when interacting with cobalt ions has been targeted for on-site detection. The chemosensors are grouped in various categories and their comparison and the discussion of computational studies will enable readers to have a quick overview and help in designing effective and efficient probes for the detection of cobalt in the field of chemo-sensing.

Elucidating the redox activity of cobalt-1,2,3,4-cyclopentane-tetracarboxylic acid and 1,2,4,5-benzene-tetracarboxylic acid-based metal-organic frameworks for a hybrid supercapacitor.

The development of electrode materials with extraordinary energy densities or high power densities has experienced a spectacular upsurge because of significant advances in energy storage technology. In recent years, the family of metal-organic frameworks (MOFs) has become an essential contender for electrode materials. Herein, two cobalt-based MOFs are synthesized with distinct linkers named 1,2,4,5-benzene-tetra-carboxylic acid (BTCA) and 1,2,3,4-cyclopentane-tetracarboxylic acid (CPTC). Investigations have been rigorously conducted to fully understand the effect of linkers on the electrochemical properties of Co-based MOFs. The best sample among the MOFs was used with activated carbon to create a battery-supercapacitor hybrid device. Due to its noteworthy results, specific capacity (100.3 C g-1), energy density (23 W h kg-1), power density (3400 W kg-1) and with the lowest ESR value of 0.4 Ω as well as its 95.4% capacity retention, the fabricated hybrid device was discovered to be very appealing for applications demanding energy storage. An approach for evaluating battery-supercapacitors was employed by quantifying the capacitive and diffusive contributions using Dunn's model to reflect the bulk and surface processes occurring during charge storage. This study fills the gap between supercapacitors and batteries, as well as providing a roadmap for creating a new generation of energy storage technologies with improved features.

A dual-emitting Rhodamine B-encapsulated Zn-based MOF for the selective sensing of Chromium(VI).

A Rhodamine B-Zn-MOF composite (RhB-Zn-MOF) with dual emission intensity was synthesized through one pot synthesis by in-situ encapsulation of Rhodamine-B dye on a new Zn-MOF metal-organic framework [(Zn(OAc)2(4-BrIPh) (1,10-phenonthroline)(H2O)].H2O, (4-BrIPh = 4-Bromoisophthalic acid). The synthesized encapsulated material was characterized by elemental analysis, FTIR, UV-Visible spectroscopy, TGA, single crystal and powder X-ray diffraction and photoluminescence spectroscopy. The results showed that the synthesized composite, RhB-Zn-MOF could be used as an efficient probe for the selective sensing of Cr(VI) in the presence of Cr(III) as well as other metal ions.

Synthesis, Crystal Structure and Fluorimetric Study of 2-phenylphthalazin-1(2H)-one: a Highly Selective Florescent Chemosensor for Detection of Fe3+ and Fe2+ Metal Ions.

A ligand, 2-phenylphthalazin-1(2H)-one (K), was synthesized by refluxing 2-formylbenzoic acid with phenyl hydrazine in presence of ethanol. FTIR, elemental analysis and single crystal XRD techniques were used to elucidate the structure. Fluorimetric turn-off response was recorded when solution of ligand (K) in DMF was treated with aqueous solution of Fe3+ and Fe2+ metal ions. No specific changes were observed on addition of other metal ions (Pb2+, Cd2+, Mn2+, Zn2+, Ba2+, Ni2+, Al3+, Ag1+, Co2+, Ca2+, Cu2+, Mg2+, Cr3+). Limit of Detection (LOD) was calculated for Fe2 and Fe3+as 2.4 µM and 2.5µM respectively, which is quite below to the recommended value 5.4 µM of the Environment Protection Agency of USA. Association constants for Fe3+ and Fe2+ metal ions were determined as 6 × 10-4 M-1 and 3.6 × 10-4 M-1 respectively. Benesi-Hildebrand plot confirmed 1:1 binding ratio between metal ions and ligand.

Redox active pyridine-3,5-di-carboxylate- and 1,2,3,4-cyclopentane tetra-carboxylate-based cobalt metal-organic frameworks for hybrid supercapacitors.

In the pursuit of developing superior energy storage devices, an integrated approach has been advocated to harness the desirable features of both batteries and supercapacitors, particularly their high energy density, and high-power density. Consequently, the emergence of hybrid supercapacitors has become a subject of increasing interest, as they offer the potential to merge the complementary attributes of these two technologies into a single device, thereby surpassing the limitations of conventional energy storage systems. In this context the Metal-Organic Frameworks (MOFs), consisting of metal centers and organic linkers, have emerged as highly trending materials for energy storage by virtue of their high porosity. Here, we investigate the electrochemical performance of cobalt-pyridine-3,5-di-carboxylate-MOF (Co-PDC-MOF) and cobalt-1,2,3,4-cyclopentane tetra-carboxylate-MOF (Co-CPTC-MOF). In the setup involving the analysis of Co-PDC-MOF and Co-CPTC-MOF materials, a configuration comprising three electrodes was utilized. Drawing upon the promising initial properties of CPTC, a battery device was fabricated, comprising Co-CPTC-MOF, and activated carbon (AC) electrodes. Retaining a reversible capacity of 97% the device showcased impressive energy and power density of 20.7 W h g-1 and 2608.5 W kg-1, respectively. Dunn's model was employed, to gain deeper insights into the capacitive and diffusive contributions of the device.

A dispersive liquid-liquid microextraction followed by reverse-phase high-performance liquid chromatography for QuEChERS determination of chlorogenic acid.

INTRODUCTION: The presence of chlorogenic acid (CGA) not only imparts a characteristic flavour to foods but also makes them useful against chronic diseases and metabolic syndromes, especially diabetes mellitus and asthma. OBJECTIVES: The present study was designed to develop a quick, easy, cheap, effective, rugged, and safe (QuEChERS) and pragmatic method to analyse CGA in plant-based products by applying dispersive liquid-liquid microextraction (DLLME) followed by reverse-phase high-performance liquid chromatography under a diode array detector (RP-HPLC-DAD). METHODOLOGY: The DLLME was carried out using Triton X-100 as a dispersant and ethanol as an extraction solvent, while method development and validation activities were performed on a Shimadzu 10-AT HPLC-DAD system equipped with C-18 columns as stationary phases. RESULTS: The well-resolved peak for the standard CGA was observed at 2.92 min for the mobile phase comprising 0.1% aqueous formic acid-ethanol (22:78 v/v) of pH 3.0 programmed under an isocratic flow rate of 1.0 mL/min. The developed method was found to be linear (R2 = 0.9976) over 1-500 µg/mL of CGA concentration at 328 nm. Moreover, the assay was found to be repeatable with RSD ≤ 5.0, and the limit of detection (LOD) and limit of quantification (LOQ) were 0.0281 and 0.0853 µg/mL of CGA, respectively. The DLLME offered an overall recovery rate between 97.60% and 99.54% at an acceptable level of reproducibility [relative standard deviation (RSD) ≤ 5.0]. CONCLUSION: The developed assay was found to be a QuEChERS and pragmatic choice for the high-throughput analysis of CGA in plant-based products/foods. Finally, the analysis revealed the presence of an ample level of CGA in guava fruit in addition to coffee beans and black tea.

Synthesis and Biomedical Applications of Zirconium Nanoparticles: Advanced Leaps and Bounds in the Recent Past.

Many synthetic routes manufacture zirconium nanoparticles in metal oxide, nitride, and other combination forms. Coupled with other variables such as concentration, pH, and form of precursor used, the various synthetic methods support synthesizing the zirconium metal oxide nanoparticles with changed features. Various synthetic methods were studied, such as sol-gel, hydrothermal, laser ablation, and precipitation. All have different synthetic routes, different precursors and solvents were sued, and the product was characterized by SEM, TEM, photo luminance spectroscopy, UV-absorption spectroscopy, and powder X-ray diffraction. X-ray diffraction determined the crystal structure by identifying the crystal shape, arrangement of atoms, and spacing between them. SEM and TEM studied the particle size and morphology of nanoparticles. UV-visible absorption spectroscopy and PL spectroscopy were used for the determination of optical properties of nanoparticles. Zirconium oxide nanoparticles have many applications in the medical field. The review study primarily focuses on the efficient combination of zirconium dioxide with other additive materials and functionalization techniques used to improve the material's properties, assisting the use of the material in hip arthroplasty and bone tissue applications. The development of sophisticated near-infrared (NIR) absorbing small molecules for useful phototheranostic applications was discussed in this paper.

Synthesis, crystal structures and, magnetic and photoluminescence properties of lanthanide-based metal-organic frameworks constructed with 2,5-dihydroxybenzene-1,4-dicarboxylic acid.

Four new lanthanide(iii) coordination polymers (1-4) have been synthesized by using 2,5-dihydroxybenzene-1,4-dicarboxylate (Dhbdc, C8H6O6 2-) as a ligand and characterized by elemental analysis, infrared spectroscopy, TGA-DSC (Thermogravimetric Analysis-Differential Scanning Calorimetry) and single crystal X-ray diffraction studies. The isolated complexes include; [Ce(Dhbdc)(H2O)3Cl] n (1) and [Ln(Dhbdc)1.5(H2O)2] n ·3n(C2H6O)·nH2O [Ln = Eu (2), Gd (3) and Tb (4)]. The structural analysis reveals that compound 1 is a two-dimensional polymer in which the cerium atoms are coordinated by six oxygen and two bridging chloride ions adopting a dodecahedral geometry. The compounds 2-4 are isomorphous and their extended structures consist of three-dimensional supramolecular frameworks encapsulating [001] channels occupied by the guest water and ethanol molecules. The metal atoms in 2-4 exhibit a square antiprism geometry. All these compounds have O-H⋯O hydrogen bonds originating from the coordinated water and solvent molecules that help to consolidate the structures. The compounds 1, 3 and 4 were investigated for magnetic properties and they exhibited weak antiferromagnetic coupling interactions between the lanthanides as per the Curie Weiss law. Anisotropic nature of 3 and 4 has been depicted as per magnetization versus field plots. Complex 4 behaves as a soft magnetic material as compared to 3. The luminescence studies indicate that compounds 2, 3 and 4 show ligand-centred fluorescence, which is significantly enhanced in the case of 4.

Antioxidant activity, α-glucosidase inhibition and phytochemical profiling of Hyophorbe lagenicaulis leaf extracts.

BACKGROUND: Diabetes mellitus type II (DMT-2) is a widely spread metabolic disorder both in developed and developing countries. The role of oxidative stress is well established in DMT-2 pathogenesis. The synthetic drugs for DMT-2 are associated with serious side complications. Antioxidant and α-glucosidase inhibitory actions of phytochemicals from various plant species are considered as an alternative to synthetic drugs for DMT-2 management. The present study aimed to evaluate the antioxidant activity, α-glucosidase inhibitory potential and phytochemical profiling of Hyophorbe lagenicaulis. METHODS: The total phenolic and flavonoid contents, in vitro antioxidant activity (α, α-diphenyl-ß-picrylhydrazyl (DPPH) free radical scavenging and phosphomolybdenum method) and α-glucosidase inhibition of ultrasonicated hydroethanolic H. lagenicaulis leaf extracts were determined spectrophotometrically. The results of DPPH assay and α-glucosidase inhibition were reported in terms of IC50 value. The phytochemical profiling was accomplished by UHPLC-Q-TOF/MS/MS technique. RESULTS AND DISCUSSION: Findings leaped 60% ethanolic extract as rich fraction regarding total phenolic and flavonoid contents. The 60% ethanolic fraction was a promising source of natural antioxidants and α-glucosidase inhibitory agents as indicated by anti-radical and enzyme inibitory activities. Kaempferol, rutin, hesperetin 5-O-glucoside, kaempferol-coumaroyl-glucoside, luteolin 3-glucoside, Isorhamnetin-3-O-rutinoside, trimethoxyflavone derivatives and citric acid were identified by UHPLC-Q-TOF-MS/MS. These compounds were believed to be responsible for the strong antioxidant and enzyme inhibitory activity of plant extracts. The extensive metabolite profiling of H. lagenicaulis was carried out the first time as never reported previously. The H. lagenicaulis might be an appropriate choice to manage diabetes mellitus in an alternate way. The findings may be further exploited extensively for toxicity evaluation to proceed with functional food development having antidiabetic attributes.

Enhancement of fuel characteristics of rice husk via torrefaction process.

Torrefaction, is a pretreatment process in the conversion of various biomass feedstocks into an efficient solid fuel. In the present research, rice husk was torrefied at 200°C, 250°C, and 300°C for 10, 30, 90, and 150 minutes under a non-oxidative environment. The energy yield and mass yield of torrefied solid residues ranged from 51.3% to 96.8%, and 49.1% to 95.1%, respectively, under torrefaction conditions. Increasing the residence time and temperature of thermal treatment causes a rise in carbon content from 32.45% to 48.5%, and raises the calorific value from 16.48 MJ/kg to 19.82 MJ/kg. The torrefaction process also reduced the swelling tendency of the biomass in water from its initial value of 308% to 92% only. Various other characterizations including Fourier transform infrared radiation, thermogravimetric analysis (TGA) and scanning electron microscopy were performed to analyze the structural and textural aspects of torrefied biomass. The TGA and derivative thermogravimetric analysis curves indicated that torrefaction affected the hemicellulose fraction of biomass significantly. The surface morphology of thermolyzed samples revealed the rupture of the surface induced by the torrefaction process. Overall, the torrefaction process has not only improved the fuel characteristics of the rice husk but also enhanced its hydrophobicity.

Antioxidant activity, Hypoglycemic potential and metabolite profiling of Hyophorbe indica leaf extract.

Current work was performed to evaluate antioxidant activity, α-glucosidase inhibition, phytochemical profiling and in vivo hypoglycemic activity of freeze dried, ultrasonicated Hyophorbe indica leaf extracts. The highest total phenolic contents of 208.77±2.11 mg GAE/g DE and total flavonoid contents of 173.90±2.30 mg Rutin/g DE were obtained in 60% ethanol extract. The 60% ethanol extract exhibited maximum DPPH radical scavenging with IC50 value of 35.35±0.189µg/mL and total antioxidant power of 330.26±3.13 (ASE/g PE), respectively. The highest α-glucosidase inhibition (IC50 36.52 ± 0.08µg/mL) was also observed for 60% ethanol extract. The 60% ethanol extract at dose of 450 mg/kg body weight reduced blood glucose level of alloxan induced diabetic mice by 51.41% which was quite comparable with metformin (56.67%). Twelve compounds namely citric acid, procyanidin B3, epicatechin, procyanidin B2, catechin, catechin derivative, procyanidin B1, apigenin-c-hexocide-c-hexocide, kaempferol, kaempferol derivative, quinic acid derivative and gallic acid have been identified by using UHPLC-Q-TOF-MS/MS in 60% ethanol extract.

Anilinium-3-carboxyl-ate 3-carb-oxy-anilinium nitrate.

The title compound, C7H8NO2(+)·NO3(-)·C7H7NO2, exists in the form of a protonated dimer of two anilinium-3-carboxyl-ate mol-ecules related by an inversion center, and a nitrate anion located on a twofold rotation axis. The bridging H atom occupies, with equal probability, the two sites associated with the carboxyl atoms. In addition to the strong O-H⋯O hydrogen bond, in the crystal, the various units are linked via N-H⋯O and C-H⋯O hydrogen bonds forming a three-dimensional structure.

catena-Poly[[[penta-aqua-cerium(III)]-µ-pyridine-2,4,6-tricarboxyl-ato-κ(4)N,O(2),O(6):O(6')] tetra-hydrate].

The Ce(III) atom in the title compound, {[Ce(C(8)H(2)NO(6))(H(2)O)(5)]·4H(2)O}(n), is N,O,O'-chelated by the carboxyl-ate trianion and is coordinated by five water mol-ecules; a carboxyl O atom from an adjacent trianion bridges the Ce(III) atom, resulting in a chain running along the a axis. The nine atoms surrounding the metal atom comprise a tricapped trigonal-prismatic polyhedron. The coordinated and lattice water mol-ecules inter-act with each other and with the carboxyl O atoms by O-H⋯O hydrogen bonds, generating a three-dimensional network.

4-Chloro-N-cyclo-hexyl-benzene-sulfonamide.

The title compound, C(12)H(16)ClNO(2)S, adopts an L-shaped conformation, with the central C-S-N-C torsion angle being -78.0 (2)°. The cyclo-hexyl ring adopts a chair conformation. In the crystal, adjacent mol-ecules are connected by pairs of N-H⋯O hydrogen bonds around an inversion centre, forming cyclic dimers [graph set R(2) (2)(8)].

4-[(4-Methyl-benzene-sulfonamido)-meth-yl]cyclo-hexa-necarb-oxy-lic acid.

The title compound, C(15)H(21)NO(4)S, crystallized with two independent mol-ecules in the asymmetric unit in which the dihedral angles between the mean planes of the benzene and cyclo-hexane rings are 78.3 (2) and 67.6 (2)°. The substituents of the cyclo-hexyl rings are in equatorial orientations. In the crystal, both mol-ecules form R(2) (2)(6) carb-oxy-lic acid inversion dimers via pairs of O-H⋯O hydrogen bonds. Further N-H⋯O and C-H⋯O inter-actions generate a three-dimensional network.

2-(4-Acetamido-benzene-sulfonamido)-benzoic acid.

In the title compound, C(15)H(14)N(2)O(5)S, two similar mol-ecules comprise the asymmetric unit, which are linked by strong inter-molecular C-H⋯π inter-actions. Both mol-ecules are bent, with dihedral angles of 71.94 (16) and 74.62 (15)° between the benzene rings. An intra-molecular N-H⋯O hydrogen bond occurs in each mol-ecule. In the crystal, inter-molecular N-H⋯O and O-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network.

catena-Poly[bis-(propane-1,3-diaminium) [[aqua-(sulfato-κO)bis-(sulfato-κO,O')cerate(IV)]-µ-sulfato-κO,O':O''] dihydrate].

The Ce(IV) atom in the title salt, {(H(3)NCH(2)CH(2)CH(2)NH(3))(2)[Ce(SO(4))(4)(H(2)O)]·2H(2)O}(n), exists in a monocapped square-anti-prismatic coordination geometry. The water-coordinated metal atom is bonded to four sulfate ions; one of them is monodentate and two function in a chelating mode. The fourth is also chelating but it uses one of the other two O atoms to bind to an adjacent metal atom, generating a polyanionic chain. The cations are linked to the polyanionic chain as well as to the uncoordinated water mol-ecules, resulting in an O-H⋯O and N-H⋯O hydrogen-bonded three-dimensional network.

4-{[(4-Methyl-phen-yl)sulfon-yl]amino}-benzoic acid.

In the title compound, C(14)H(13)NO(4)S, the dihedral angle between the aromatic rings is 35.47 (10)°. In the crystal, adjacent mol-ecules are connected by pairs of O-H⋯O hydrogen bonds, forming head-to-head centrosymmetric dimers typical for carb-oxy-lic acids. Adjacent dimers are further linked through C-H⋯O inter-actions on one side and N-H⋯O inter-actions on the other, generating [010] chains.