Project description:In the past decades, porous coordination polymers (PCPs) based fluorescent (FL) sensors have received intense attention due to their promising applications. In this work, a soluble Zn-PCP is presented as a sensitive probe towards explosive molecules, chromate, and dichromate ions. In former reports, PCP sensors were usually ground into fine powders and then dispersed in solvents to form FL emulsion for sensing applications. However, their insoluble characters would cause the sensing accuracy which is prone to interference from environmental effects. While in this work, the as-made PCP could be directly soluble in organic solvents to form a clear solution with bright blue emission, representing the first soluble PCP based fluorescence sensor to probe explosive molecules under a homogeneous environment. Moreover, the FL PCP solution also shows sensitive detection behaviors towards the toxic anions of CrO42- and Cr2O72-, which exhibit a good linear relationship between the fluorescence intensity of Zn-PCP and the concentrations of both analytes. This work provides a reference for designing task-specific PCP sensors utilized under a homogeneous environment.
Project description:A luminescent coordination polymer with the overall formula {[Zn(tr2btd)(bpdc)]∙DMF}n (where tr2btd = 4,7-di(1H-1,2,4-triazol-1-yl)-2,1,3-benzothiadiazole; bpdc = 4,4'-biphenyldicarboxylate) was synthesized and characterized by single-crystal and powder X-ray diffraction, thermogravimetric, infrared spectroscopy, and elemental analyses. Luminescent properties of the obtained compound were studied in detail both in the solid state and as a suspension in N,N-dimethylacetamide (DMA). It was found that {[Zn(tr2btd)(bpdc)]∙DMF}n exhibits bright turquoise luminescence with excellent quantum efficiency and demonstrates turn-on fluorescence enhancement effect upon soaking in DMA Al3+ solution. Fluorescence titration experiments were carried out and the detection limit for Al3+ ions was calculated to be 120 nM, which is among the lowest reported values for similar materials. Moreover, compound demonstrated excellent selectivity and reusability, and the mechanism of the response is discussed. These results indicate that {[Zn(tr2btd)(bpdc)]∙DMF}n is a promising probe for sensitive fluorescent Al3+ detection.
Project description:A new Zn(II)-based coordination polymer (1) comprising the Schiff base ligand obtained by the condensation of 5-aminosalicylic acid and salicylaldehyde has been synthesized. This newly synthesized compound has been characterized by analytical and spectroscopic methods, and finally, by single-crystal X-ray diffraction technique in this study. The X-ray analysis reveals a distorted tetrahedral environment around the central Zn(II) center. This compound has been used as a sensitive and selective fluorescent sensor for acetone and Ag+ cations. The photoluminescence measurements indicate that in the presence of acetone, the emission intensity of 1 displays quenching at room temperature. However, other organic solvents caused meagre changes in the emission intensity of 1. Additionally, the fluorescence intensity of 1 has been examined in the presence of different ketones viz. cyclohexanone, 4-heptanone, and 5-nonanone, to assess the interaction between the C=O group of the ketones and the molecular framework of 1. Moreover, 1 displays a selective recognition of Ag+ in the aqueous medium by an enhancement in its fluorescence intensity, representing its high sensitivity for the detection of Ag+ ions in a water sample. Additionally, 1 displays the selective adsorption of cationic dyes (methylene blue and rhodamine B). Hence, 1 showcases its potential as an excellent luminescent probe to detect acetone, other ketones, and Ag+ with an exceptional selectivity, and displaying a selective adsorption of cationic dye molecules.
Project description:A Dy(III) coordination polymer (CP), [Dy(spasds)(H2O)2]n (1) (Na2Hspasds = 5-(4-sulfophenylazo)salicylic disodium salt), has been synthesized using a hydrothermal method and characterized. 1 features a 2D layered structure, where the spasda3- anions act as pentadentate ligands, adopting carboxylate, sulfonate and phenolate groups to bridge with four Dy centers in η3-μ1: μ2, η2-μ1: μ1, and monodentate coordination modes, respectively. It possesses a unique (4,4)-connected net with a Schläfli symbol of {44·62}{4}2. The luminescence study revealed that 1 exhibited a broad fluorescent emission band at 392 nm. Moreover, the visual blue color has been confirmed by the CIE plot. 1 can serve as a dual-functional luminescent sensor toward Fe3+ and MnO4- through the luminescence quenching effect, with limits of detection (LODs) of 9.30 × 10-7 and 1.19 × 10-6 M, respectively. The LODs are relatively low in comparison with those of the reported CP-based sensors for Fe3+ and MnO4-. In addition, 1 also has high selectivity and remarkable anti-interference ability, as well as good recyclability for at least five cycles. Furthermore, the potential application of the sensor for the detection of Fe3+ and MnO4- was studied through simulated wastewater samples with different concentrations. The possible sensing mechanisms were investigated using Ultraviolet-Visible (UV-Vis) absorption spectroscopy and density functional theory (DFT) calculations. The results revealed that the luminescence turn-off effects toward Fe3+ and MnO4- were caused by competitive absorption and photoinduced electron transfer (PET), and competitive absorption and inner filter effect (IFE), respectively.
Project description:A highly selective detection of trace water in organic solvents is urgently required for the chemical industry. In this work, the simple sonochemical method was used for producing a luminescent sensor, [Zn(H2dhtp)(2,2'-bpy)(H2O)]n (Zn-CP) (H2dhtp2- = 2,5-dihydroxyterephthalate and 2,2'-bpy = 2,2'-bipyridine). Zn-CP exhibits reversible thermally-induced and methanol-mediated structural transformation. Importantly, Zn-CP has exceptional water sensing performance in both dry methanol and dry ethanol, with high selectivity, wide linear ranges, and a low limit of detection (LOD) of 0.08% (v/v). Upon the incremental addition of water, the luminescent intensities enhanced and shifted, along with the emission color changing from green to greenish yellow. In addition, Zn-CP can detect methanol selectively through turn-on luminescence intensity with LODs of 0.28, 0.52, and 0.35% (v/v) in dry ethanol, dry n-propanol, and dry n-butanol, respectively. The excited-state proton transfer of linker H2dhtp2-via enol-keto tautomerism and collaboration with structural transformation could be attributed to the sensing mechanism.
Project description:A variety of nanoparticles (NPs) including Ag, Au, Pd, Cr and mixed Cu/Fe have been synthesized in a non-activated (without solvent removal) one dimensional coordination polymer (CP) of Zn(II) via two different mechanisms, acid formation and redox activity of the framework. Main driving force to grow these NPs within the cavities of CP is the presence of free oxygens of one of the monodentate carboxylate groups of BDC ligand. These free oxygens act as anchoring sites for the metal ions of the metal precursors. Chemical and physical characteristics of the NPs within the framework have been evaluated by the high resolution transmission electron microscopic (HRTEM) images. Excluding Ag(0) and Pd(0) other NPs are present as combinations of their elemental as well as oxide forms (Au/Au2O3, Cr/Cr2O3/CrO2 and Cu/Cu2O, Fe/FeO). Synthesized Ag NPs within the framework show remarkable antibacterial efficacy at extremely low concentrations. Ag, Au and Cu/Fe NPs show ferromagnetic properties within the framework at room temperature. This polymer has potential to sequester highly toxic Cr(VI) to non toxic Cr(0), Cr(III) and Cr(IV) species.
Project description:The present study reports on a 2D lamellar coordination polymer (CP) of {[Zn(µ3-pmdc)(H2O)]·H2O}n formula (pmdc = pyrimidine-4,6-dicarboxylate). This CP is synthesized under an appropriate acid-base reaction between the gently mortared reagents in the solid state through a solvent-free procedure that avoids the presence of concomitant byproducts. The X-ray crystal structure reveals the occurrence of Zn2 entities connected through carboxylate groups of pmdc, which behave as triconnected nodes, giving rise to six-membered ring-based layers that are piled up through hydrogen bonding interactions. In addition to a routine physico-chemical characterization, the thermal evolution of the compound has been studied by combining thermogravimetric and thermodiffractometric data. The photoluminescence properties are characterized in the solid state and the processes governing the spectra are described using time-dependent density-functional theory (TD-DFT) with two different approaches employing different program packages. The emissive capacity of the material is further analyzed according to the dehydration and decreasing temperature of the polycrystalline sample.
Project description:Some Trichoderma strains are known for their capacity to produce harzianic acid, a metabolite belonging to the tetramic acid derivatives. Harzianic acid has interesting biological properties, such as antimicrobial activities against phytopathogenic fungi and promotion of plant growth. It also possesses remarkable chemical properties, including the chelating properties toward essential transition metals, which might be related to the biological activities. Increasing knowledge on chelating properties might be relevant for understanding the various beneficial effects of harzianic acid in the interaction between the producer fungi and plants. In this work, the coordination capacity of harzianic acid was studied to evaluate the formation and stability of complexes formed with toxic heavy metals (i.e., Cd2+, Co2+, Ni2+, and Pb2+), which might have a crucial role in the tolerance of plants growing in metal-contaminated soils and in abiotic stress.
Project description:A coumarin based probe for the efficient detection of hydrogen sulfide in aqueous medium is reported. The investigated coumarine-based derivative forms spherical nanoparticles in aqueous media. In presence of Pd2+, a metallosupramolecular coordination polymer is formed, which is accompanied by quenching of the coumarin emission at 390 nm. Its Pd2+ complex could be used as a probe for chemoselective detection of monohydrogensulfide (HS-). Presence of HS- leads to a'turn-on' fluorescence signal, resulting from decomplexation of Pd2+ from the metallosupramolecular probe. The probe was successfully applied for qualitative and quantitative detection of HS- in different sources of water directly collected from sea, river, tap and laboratory drain water, as well as in growth media for aquatic species.
Project description:A novel fluorescence material H2Sr2(bqdc)3(phen)2 (1) for trace recognition of organic pollutant and toxic metal ions is designed and prepared by two weak fluorescent ligands and Sr2+. The latter was selected although it played no role in the modulation process of luminescence and despite low-cost, alkaline earth, metal-organic coordination polymers lacking competitive functionality. The strong fluorescence of the fluorescence material was based on the propeller configuration of the metal-organic coordination polymer, which was characterized by X-ray single crystal diffraction showing that the N active sites inside the crystal channels can interact with external guests. Convenient fluorescence detection of 3-AT can be realized using an ultraviolet lamp and test strip and the determination of Cd2+ showed good reusability with a detection limit of 1 × 10-9 mol L-1, which is lower than the standard stipulated by the Environmental Protection Agency. Detailed experiments results revealed that the material was a promising candidate for specifically recognizing amitrole and Cd2+ because of its selective fluorescence quenching and sensitive detection in water.