Hydrogen-bond organic-framework-based electrochemical sensor for highly sensitive determination of trace cadmium ions in environmental and e-cigarette samples.

BACKGROUND: The heavy metal ion Cd2+ is acutely toxic, and excessive concentrations can have adverse effects on human production and life, and even lead to significant public health risks and environmental impacts. There are several mature non-electrochemical methods for heavy metal detection, but these methods are characterized by high cost, which makes it difficult to be applied to the field for timely detection. Therefore, it is necessary to prepare a new electrochemical sensor that is environmentally friendly and capable of detecting Cd2+ in the environment quickly, easily and sensitively. RESULTS: In this study, hydrogen-bonded organic frameworks (HOFs) were synthesized by a simple hydrothermal reaction. The prepared materials consisted of only C, N and O and had a thin lamellar structure. The HOFs were integrated into a novel electrochemical sensor to achieve accurate detection of Cd2+ ions in real aqueous environments by square wave anodic dissolution voltammetry. The sensor has a wide linear range and a detection limit as low as 0.13 µg/L. Several real water samples, such as tap water, lake water, and e-cigarette digest, were analyzed to simulate the working environment of the sensor, and the results showed that the recoveries of Cd2+ ranged from 95.75 % to 101.2 %. SIGNIFICANCE: We pioneered the detection of heavy metal ions Cd2+ in e-cigarette digestate samples with the innovative use of HOFs as the sensor material, which demonstrated the potential application in electrochemical sensing with extremely low background current value and high sensitivity, providing new ideas for environmental monitoring and public health control.

Preparation, Structures, Photoluminescence and Semiconductive Properties of Two Novel Lanthanide Mercury Materials with a 3-D Framework Structure.

Two novel lanthanide mercury materials, [Gd(IA)3(H3O)2Hg3Br6]n·2nCl (1) and [La(IA)3(H3O)2Hg3Br6]n·2nCl (2) (IA = isonicotinic anion), have been prepared under solvothermal conditions and characterized by single-crystal X-ray diffraction techniques. They are isomorphic and characterized by a three-dimensional (3-D) framework structure. The lanthanide ions are bound by eight oxygen atoms to exhibit a square antiprismatic geometry. The solid-state photoluminescence experiment discovers that compound 1 shows a strong emission in the red region. Compound 1 possesses CIE (Commission Internationale de I'Éclairage) chromaticity coordinates of 0.7347 and 0.2653. Its CCT (correlated color temperature) is 6514 K. Compound 2 displays yellow photoluminescence and it has CIE chromaticity coordinates of 0.4411 and 0.5151. The CCT of compound 2 is 3633 K. Solid-state UV/Vis diffuse reflectance spectra revealed that their semiconductor band gaps are 2.16 eV and 2.85 eV, respectively.

ZIF-67 based CoS2 self-assembled on graphitic carbon nitride microtubular for sensitive electrochemical detection of paraquat in fruits.

Paraquat (PQ) is a widely used and harmful herbicide that must be detected in the environment. This study reports a novel composite (CoS2-GCN) prepared by assembling cobalt disulfide (CoS2) derived from metal-organic frameworks (MOFs) on graphitic carbon nitride (GCN). An electrochemical sensor (CoS2-GCN/ glassy carbon electrode (GCE)) was successfully prepared by modifying CoS2-GCN onto a GCE to sensitively detect PQ. Different concentrations of PQ were detected using square-wave voltammetry, and the CoS2-GCN/GCE electrochemical sensor showed remarkable response signals for PQ in the range of 20 - 1000 nM and 1 - 13 µM, with a detection limit of 4.13 nM (S/N = 3). The CoS2-GCN/GCE electrochemical sensor exhibited high stability, reproducibility, and immunity to interference, which were attributed to the synergistic effects of CoS2 and GCN. In addition, the CoS2-GCN/GCE electrochemical sensor showed high applicability for the analysis of fruit samples. Therefore, the proposed sensor has potential applications in PQ detection.

Crystal structure and photophysical properties of a novel polyoxomolybdate porphyrin.

A novel polyoxomolybdate with a diprotonated porphyrin as counter-cation, namely, 5,10,15,20-tetrakis(4-carboxyphenyl)-21H,22H,23H,24H-porphine(2+) hexamolybdate(VI) pentahydrate, (C48H32N4O8)[Mo6O19]·5H2O or (H2TCPP)[Mo6O19]·5H2O, I, was prepared via the hydrothermal reaction of MoCl5, 5,10,15,20-tetrakis(4-carboxyphenyl)-21H,23H-porphine (TCPP) and distilled water. The crystal structure of hydrated polyoxometalate (POM) salt I was characterized by single-crystal X-ray diffraction. The compound is characterized by an isolated (zero-dimensional, 0D) structure, because it cannot extend via covalent bonds. The structure contains one [Mo6O19]2- anion, one (H2TCPP)2+ cation and five lattice water molecules. Each of the Mo6+ ions is six-coordinated and displays a distorted octahedral motif. The (H2TCPP)2+ cation displays a distorted saddle motif. A three-dimensional (3D) supramolecular framework is formed via hydrogen-bonding interactions. The compound shows a red photoluminescence emission.

A one-dimensional manganese(III)-porphyrin coordination polymer: crystal structure and photophysical properties.

A novel manganese(III)-porphyrin complex, namely, catena-poly[[chloridomanganese(III)]-µ2-5,10,15,20-tetrakis(pyridin-3-yl)-21H,23H-porphinato(2-)-κ5N21,N22,N23,N24:N5], [MnCl(C40H24N8)]n, 1, was prepared by the hydrothermal reaction of manganese chloride with 5,10,15,20-tetrakis(pyridin-3-yl)-21H,23H-porphine. The crystal structure was determined by single-crystal X-ray diffraction. The porphyrin macrocycle exhibits a saddle-like distortion geometry. The MnIII atom has a six-coordination geometry. Each porphyrin unit links to two neighbouring units to yield a one-dimensional coordination polymer. These chains are further interlinked by hydrogen bonds to form a two-dimensional network. The complex shows red photoluminescence emission bands in ethanol solution, which can be attributed to ligand-to-ligand charge transfer (LLCT) accompanied by partial metal-to-ligand charge transfer (MLCT), as revealed by TDDFT calculations.

Organic-inorganic Hybrid ([BrCH2 CH2 N(CH3 )3 ]+ 2 [CdBr4 ]2- ) with Unusual Ferroelectric and Switchable Dielectric Bifunctional Properties over Different Temperature Range.

Both ferroelectric and switchable dielectric behaviors are of great academic value and practical significance, but they usually exist alone. If combine the two properties into one compound, it will be more valuable in practical application. In this paper, quasi-spherical (2-bromoethyl) trimethylammonium cation was used to match with [CdBr4 ]2- anion, and a new organic-inorganic hybrid compound ([BrCH2 CH2 N(CH3 )3 ]+ 2 [CdBr4 ]2- , BETABCdBr) was obtained and carefully characterized. The results indicate that this compound undergoes two continuous reversible phase transition around 342 K and 390 K. It could respectively exhibit ferroelectric and switchable dielectric properties over different temperature range. This work may provide a new clue to explore new types of bifunctional phase transition smart materials to meet various application requirements.

Structure and photophysical and electrochemical properties of a copper porphyrin complex with a three-dimensional framework.

Porphyrins and metalloporphyrins can generally show attractive structural motifs and interesting properties. A new copper porphyrin, namely poly[[µ-chlorido-[µ5-5,10,15,20-tetrakis(pyridin-4-yl)-21H,23H-porphine]tricopper(I)] [aquadichloridocopper(II)]], {[Cu3(C40H24N8)Cl][CuCl2(H2O)]}n (1), was synthesized by the self-assembly of copper chloride with 5,10,15,20-tetrakis(pyridin-4-yl)-21H,23H-porphine under solvothermal conditions. The structure of this copper porphyrin was characterized by single-crystal X-ray crystallography and elemental analysis. The porphyrin macrocycle shows a distorted saddle geometry, with the four pyrrole rings slightly distorted in an alternating mode either upwards or downwards. The copper ions show three-coordinated triangular and four-coordinated square-planar geometries. Every copper-porphyrin unit connects to 12 others via four µ4-bridging Cu2Cl moieties to complete the three-dimensional framework of compound 1, with isolated CuCl2(H2O) units located in the voids. This copper porphyrin displays a red photoluminescence. Electrochemical measurements showed that compound 1 has two redox waves (E1/2 = -160 and 91 mV).

MiRNAs and LncRNAs: Dual Roles in TGF-ß Signaling-Regulated Metastasis in Lung Cancer.

Lung cancer is one of the most malignant cancers around the world, with high morbidity and mortality. Metastasis is the leading cause of lung cancer deaths and treatment failure. MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs), two groups of small non-coding RNAs (nc-RNAs), are confirmed to be lung cancer oncogenes or suppressors. Transforming growth factor-ß (TGF-ß) critically regulates lung cancer metastasis. In this review, we summarize the dual roles of miRNAs and lncRNAs in TGF-ß signaling-regulated lung cancer epithelial-mesenchymal transition (EMT), invasion, migration, stemness, and metastasis. In addition, lncRNAs, competing endogenous RNAs (ceRNAs), and circular RNAs (circRNAs) can act as miRNA sponges to suppress miRNAs, thereby mediating TGF-ß signaling-regulated lung cancer invasion, migration, and metastasis. Through this review, we hope to cast light on the regulatory mechanisms of miRNAs and lncRNAs in TGF-ß signaling-regulated lung cancer metastasis and provide new insights for lung cancer treatment.

Magnetic, Photoluminescent and Semiconductor Properties of a 4f-5d Bromide Compound.

A novel 4f-5d material (HgDy6Br12)Hg8Br24 (1) is prepared by hydrothermal reactions and structurally characterized by single crystal X-ray diffraction. Compound 1 is characterized by a two-dimensional (2D) layered structure. A photoluminescence measurement with solid-state samples shows that this compound exhibits a strong emission in the blue region. A narrow optical band gap of 1.97 eV is revealed by a solid-state UV/Vis diffuse reflectance spectrum. The variable-temperature magnetic susceptibility obeys the Curie-Weiss law (cm= c/(T-q)) with C = 0.78 K and a Weiss constant ? = -0.38 K as revealed by the magnetic measurements, suggesting the existence of an antiferromagnetic interaction.

Crystal Structure and Photophysical Properties of a Novel Dy-Hg Isonicotinic Acid Compound with One-Dimensional Chain-Like Cations.

A novel Dy-Hg compound [Dy(HIA)3(H2O)2]2n·2nHgCl4·nHgCl5·nH3O·3nH2O (1; HIA = isonicotinic acid) was prepared through a hydrothermal reaction and characterized by X-ray diffraction. The compound crystallizes in the space group of C2/c of the monoclinic system. The crystal structure of compound 1 has one-dimensional (1-D) chain-like cations. A photoluminescence experiment with a solid-state sample revealed that this compound exhibits a yellow emission band at 575 nm and, this emission band shall come from the 4f electron 4F9/2 ? 6H13/2 characteristic transfer of Dy3+ ions. The compound features CIE chromaticity coordinates of 0.5168 and 0.4824 in the yellow region. A UV-visible diffuse reflectance spectrum with a solid-state sample unveiled that this compound possesses a wide optical band gap of 3.39 eV.

Series of Lanthanide-Mercury Compounds with Three-Dimensional Structures: Rational Preparation, Structures and Properties.

Three novel Ln-Hg complexes [Ln(H2O)2(µ-IA)3Hg3Br6] n (Ln = Pr (1), Nd (2), and Er (3); HIA is isonicotinic acid) are synthesized and characterized. They feature three-dimensional (3-D) motifs. Solid-state UV/vis diffuse reflectance spectroscopy found that their band gaps are 4.91, 4.59, and 2.68 eV. It is found that lanthanide ions could adjust the band structures of semiconductors. Their photoluminescence comes from their characteristic emissions of 1D2 → 3H4 of Pr3+, 7F7/2 → 4S3/2 and 4F3/2 → 4I9/2 of Nd3+, and 4I15/2 → 4F7/2 and 4I15/2 → 4S3/2 of Er3+. The CIE chromaticity coordinate is ( x = 0.5726, y = 0.4206), ( x = 0.7268, y = 0.2732), and ( x = 0.2923, y = 0.4317). Their magnetization susceptibility totally obeys the Curie-Weiss equation with antiferromagnetic performances.

Synthesis, Structure, Photoluminescence, Energy Transfer Mechanism and Band Gap of a Terbium-Mercury Complex with a 3-D Framework.

A novel terbium-mercury compound [Tb(IA)3(H2O)2(Hg2Cl4)]n·nHgCl2·nH2O (1, HIA = isonicotinic acid) was prepared via a hydrothermal reaction and structurally characterized through single-crystal X-ray diffraction technique. This compound is characterized by a three-dimensional (3-D) framework. Photoluminescence experiments with solid-state samples uncovered that this compound can show yellow light emission with the emission peaks at 490, 545, 586 and 621 nm, respectively. These photoluminescence emission peaks are originated from the characteristic emission of the 4f electrons intrashell transition of the 5D4 → 7FJ(J = 6, 5, 4, 3) of the Tb3+ ions. An energy transfer mechanism is expatiated by applying the energy level figure of the terbiumions and isonicotinic acid. This compound possesses a remarkable CIE chromaticity coordinates (0.3525, 0.4032). A wide optical band gap of 2.51 eV of the title compound is determined by using the solid-state UV/Vis diffuse reflectance spectroscopy.

Photoluminescence, semiconductive properties and theoretical calculation of a novel bismuth biimidazole compound.

A novel bismuth biimidazole compound, [(BiCl4 )-(µ2 -Cl)2 -(BiCl4 )][(CH3 )4 -2,2'-biimidazole]2 (1) with the (CH3 )4 -2,2'-biimidazole moiety generated in situ, was successfully prepared under hydrothermal conditions and structurally characterized using a single-crystal X-ray diffraction technique. Compound 1 is characteristic of an isolated structure, consisting of [(BiCl4 )-(µ2 -Cl)2 -(BiCl4 )] and (CH3 )4 -2,2'-biimidazole moieties. Solid-state photoluminescence measurement reveals that it shows a strong emission in the blue region. Time-dependent density functional theory studies show that this emission is ascribed to metal-to-ligand charge transfer. The solid-state diffuse reflectance spectrum reveals the existence of an optical band gap of 2.09 eV, indicating that it is a semiconductor.

Preparation, Structure, Photoluminescent and Semiconductive Properties, and Theoretical Calculation of a Novel Cadmium Complex with Mixed Ligands.

A novel cadmium complex with mixed ligands [Cd(2,2'-biim)(4,4'-bipy)(H2O)(ClO4)] (ClO4)n (1) (2,2'-biim = 2,2'-biimidazole; 4,4'-bipy = 4,4'-bipyridine) has been synthesized through hydrothermal reaction and its crystal structure was determined by single-crystal X-ray diffraction technique. Single-crystal X-ray diffraction analyses revealed that complex 1 crystallizes in the space group Pna21 of the orthorhombic system and exhibits a one-dimensional zigzag chain structure consisting of [Cd(2,2'-biim)(4,4'-bipy)(H2O)(ClO4)]n n+ cationic chains and isolated ClO4 - anions. Powder photoluminescent characterization reveals that complex 1 has an emission in the green region of the spectrum. Time-dependent density functional theory (TDDFT) calculation showed that the nature of the photoluminescence of complex 1 is originated from the ligand-to-ligand charge transfer (LLCT; from the HOMO of the perchlorate anions to the LUMO of the 4,4'-bipy ligand). A wide optical band gap of 3.25 eV was found by the solid-state UV/vis diffuse reflectance spectrum.

In Situ Preparation, Structure, Photoluminescence and Theoretical Study of an Unusual Bismuth Complex.

A novel bismuth photoluminescent material, (N,N'-dimethyl-2,2'-bipy)2(Bi2Cl10) · 2H2O (1) (bipy = bipyridine), with the N,N'-dimethyl-2,2'-bipy2+ moiety obtained in situ, has been synthesized under solvothermal conditions and characterized by single-crystal X-ray diffraction. Compound 1 is characterized by an isolated structure, consisting of N,N'-dimethyl- 2,2'-bipy2+ cations, Bi2Cl10 4- anions and lattice water molecules. Photoluminescence experiments with solidstate samples discover that compound 1 exhibits a strong emission in the green region. Time-dependent density functional theory (TDDFT) calculation reveals that the essence of the photoluminescence of 1 can be assigned to the combination of the metal-to-ligand charge transfer (MLCT) (from the HOMO of the bismuth ion to the LUMO of the N,N'-dimethyl-2,2'-bipy2+ moiety) and the ligand-to-ligand charge transfer (LLCT) (from the HOMO of the chloride ions to the LUMO of the N,N'-dimethyl-2,2'-bipy2+ moiety).

Photophysical and electrochemical properties of a dysprosium-zinc tetra(4-sulfonatophenyl)porphyrin complex.

A dysprosium-zinc porphyrin, [DyZn(TPPS)H3O]n (1) (TPPS = tetra(4-sulfonatophenyl)porphyrin), was prepared through solvothermal reactions and structurally characterized by single-crystal X-ray diffraction analyses. Complex 1 features a three-dimensional (3-D) porous open framework that is thermally stable up to 400 °C. Complex 1 displays a void space of 215 Å(3), occupying 9.2% of the unit cell volume. The fluorescence spectra reveal that it shows an emission band in the red region. The fluorescence lifetime is 39 µsec and the quantum yield is 1.7%. The cyclic voltammetry (CV) measurement revealed one quasi-reversible wave with E1/2 = 0.30 V.

Synthesis, crystal structure and fluorescence of an unusual terbium carboxylate.

A novel terbium-containing fluorescent material, [Tb(CH3COO)2(H2O)3]Cl (1), has been prepared by a facile approach, i.e. an ultrasonic synthesis. Compound 1 has been structurally characterized via single-crystal X-ray diffraction and it crystallizes in the space group P21/n of the monoclinic system with four formula units in a cell. Compound 1 features a novel one-dimensional (1-D) chain-like structure. The 1-D chains are interconnected by hydrogen bonds to yield a 3-D supramolecular framework. Photoluminescent investigation reveals that compound 1 displays strong emission bands identified as the characteristic emissions of 5D4 → 7FJ (J = 3, 4, 5, 6) of Tb3+.

X-Ray crystal structure of [HSm{V(IV)O(TPPS)}]n and encapsulation of nitrogen molecules in 1-D channels.

The crystal structure of an N(2)-encapusulated MOF, which is stable under open-air conditions at ambient temperature, was determined by single-crystal X-ray diffraction at 123 K. The crystal MOF of [HSm{V(IV)O(TPPS)}](n) designed to have 1-D channels periodically constricted by porphyrins planes adsorbed N(2) at 77 K. The adsorbed N(2) molecules remained in the 1-D channels even after warming to ambient temperature. The single-crystal structure of [HSm{V(IV)O(TPPS)}](n)⊃N(2) determined by X-ray diffraction indicated that N(2) molecules trapped in the constricted parts block other N(2) molecules in 1-D channels from escaping from the MOF. Such a unique encapsulation mode provides a promising approach toward designing novel MOFs with high gas storage capacity at ambient temperature.

Two nd-zn and sm-zn isonicotinic/nicotinic Acid complexes.

The 4f-3d heterometallic complexes [Nd(L)3(H2O)2]2(ZnCl4)3n • 4nH2O (1) (L = isonicotinic acid) and [Sm(L')3(H2O)2]2(ZnCl4)n • 2nH2O (2) (L' = nicotinic acid) have been obtained by hydrothermal reactions and structurally characterized by X-ray single-crystal diffractions. Both complexes feature an infinite 1-D polycationic chain-like structure. Photoluminescent investigations reveal that both complexes display totally different emissions. The emission of complex 1 is attributed to the π → π* charge-transfer interaction of the isonicotinic acid. Complex 2 exhibits emissions in a wide range, and the emissions are ascribed to the characteristic emissions of 4G5/2 → 6HJ (J = 5/2, 7/2, 9/2, 11/2) of Sm3+ ions.

In Situ Synthesis, Crystal Structure and Fluorescence of Zn(C5H4NCO2H)2(H2O)2 • 2Cl.

Zn(C5H4NCO2H)2(H2O)2 • 2Cl (1) has been synthesized in situ via hydrothermal reaction and characterized by single crystal X-ray diffraction. The crystal belongs to monoclinic, space group P21/c with a = 6.342(2), b = 10.164(3), c = 13.717(4) Å, ß = 113.62(1)°, C12H14Cl2N2O6Zn, Mr = 418.54, V = 810.1(4) Å3, Z = 2, Dc = 1.716 g/cm3, S = 1.063, µ(MoKα) = 1.875 mm-1, F(000) = 424, R = 0.0276 and wR = 0.0780. The crystal structure analysis of 1 reveals that the title compound features a structure consisting of isolated units, based on discrete chloride ions and octahedral zinc cations six-coordinated by four oxygen and two nitrogen atoms. The chloride ions and [Zn(C5H4NCO2H)2(H2O)2]2+ moieties are interconnected by hydrogen bonding interactions to yield a 3-D supramolecular framework. Luminescent investigation reveals an emission in blue region, which may be originating from π→π* charge-transfer interaction of the pyridine-2-carboxylic acid.