Homochiral Tetraphenylethene-Based Metal-Organic Frameworks with Circularly Polarized Luminescence for Enantioselective Recognition.

A pair of water-stable and highly porous homochiral fluorescent silver-organic framework enantiomers, namely, R-Ag-BPA-TPyPE (R-1) and S-Ag-BPA-TPyPE (S-1), had been prepared as enantioselective fluorescence sensors. Combining homochiral 1,1'-binaphthyl-2,2'-diyl hydrogen phosphate (BPA) with an AIE-based ligand tetrakis[4-(pyridin-4-yl)phenyl]ethene (TPyPE) in complexes R-1 and S-1 made them possess favorable circularly polarized luminescence (CPL) properties, and their CPL spectra were almost mirror images of each other. The luminescence dissymmetry factors (glum) are ±2.2 × 10-3 for R-1 and S-1, and the absolute fluorescence quantum yields (ΦFs) are 32.0% for R-1 and S-1, respectively. Complex R-1 could enantioselectively recognize two enantiomers of amino acids in water or DMF with high Stern-Volmer constants of 236-573 M-1 and enantioselectivity ratios of 1.40-1.78.

Simultaneous capture of hydrophilic and hydrophobic compounds from complex plants by biosurfactant-assisted mechanical amorphous dispersion extraction.

A biosurfactant-assisted mechanical amorphous dispersion extraction (BA-MADE) procedure was established for the simultaneous capture of hydrophilic phenolic acids and hydrophobic tanshinones from Salvia miltiorrhiza. Single-factor experiments and the response surface methodology were used to optimize and analyze the crucial parameters for the method, such as the type and amount of amorphous-dispersion extractants, grinding time, extraction time and solid-to-liquid ratio. The optimized parameter values for the BA-MADE process were 407.02 mg of sodium chenodeoxycholate, a grinding time of 4.87 min, an extraction time of 4.92 min, and a solid-to-liquid ratio of 0.5:10 g/mL. The calibration curves of danshensu, rosmarinic acid, lithospermic acid, salvianolic acid B, salvianolic acid A, dihydrotanshinone I, cryptotanshinone, tanshinone I, and tanshinone II A exhibited good linearity in the range of 1-500 µg/mL (R2 ≥ 0.9990). The limits of detection of nine analytes ranged from 5.46 to 130 ng/mL, the relative standard deviations (RSDs) of intraday and interday precision were less than 1.95 and 3.56%, respectively, and the recoveries of the real sample were in the range of 85-113%, with RSD% below 3.21%. The BA-MADE method was compared with previously reported methods, such as heating reflux extraction, ultrasonic extraction and microwave-assisted micellar extraction, and the results demonstrated that the developed method has significant advantages in the simultaneous extraction of hydrophilic and hydrophobic active components from Salvia miltiorrhiza.

A biological luminescent metal-organic framework with high fluorescence quantum yield for the selective detection of amino acids and monosaccharides.

The biological luminescent metal-organic framework (bio-LMOF), (Me2NH2)2[Zn6O(Ade)4(TCPPE)2] (1) {H4TCPPE = tetrakis[4-(4-carboxyphenyl)phenyl]ethene, Ade = adenine} was successfully designed and synthesized under hydrothermal conditions, with two channels of different sizes. The absolute fluorescence quantum yields of complex 1 and activated 1 are up to 77.6% and 85.9%, respectively. Activated 1 exhibits outstanding water stability and excellent selective luminescence sensing for amino acids and monosaccharides. The fluorescence quenching efficiencies of activated 1 towards L-Nph and D-Nga are 86.35% and 91.60%, respectively. Besides, activated 1 also displays highly quenching responses to L-Nph and D-Nga at fairly low concentrations, and the limits of detection for L-Nph and D-Nga are estimated to be 0.149 ppm and 1.612 ppm, respectively. Meanwhile, in multiple cycling experiments, activated 1 still has excellent cycling stability. These phenomena indicate that activated 1 can be utilized as a fast responsive biological luminescent sensor, which is a rare example for bio-LMOFs.

Nitrogen-Rich Tetraphenylethene-Based Luminescent Metal-Organic Framework for Efficient Detection of Carcinogens.

The introduction of nitrogen-rich functional groups into a luminescent metal-organic framework (LMOF) can enhance its fluorescent sensing ability. In this work, we designed and synthesized a triazole-containing tetracarboxyl-substituted tetraphenylethene (TPE) ligand, tetrakis[4-(4-carboxyphenyl)(1H-1,2,3-triazol-4,1-diyl)phenyl]ethene (H4TCPTAPE), featuring a prominent aggregation-induced emission (AIE). A highly porous TPE-based LMOF [Zn3(TCPTAPE)(H2O)2(OH)2] (1) with large pores was successfully obtained via solvothermal assembly of the H4TCPTAPE ligand and Zn(II) ions, which showed a high fluorescence quantum yield of 54%. The activated 1 could selectively and sensitively detect aristolochic acid I with a high fluorescence quenching efficiency of 96% and a low detection limit of 1.02 µM, indicating that it has a potential application as a luminescence-based chemical sensor for carcinogens.

Tetraphenylethene-Based Luminescent Metal-Organic Framework for Effective Differentiation of cis/trans Isomers.

Luminescent metal-organic frameworks (LMOFs) that can effectively differentiate cis/trans isomers are rarely reported. Herein, we report a novel non-interpenetrated pillared-layered LMOF [Zn(HIPA)(BPyTPE)] (1) (BPyTPE = (E)-1,2-diphenyl-1,2-bis(4-(pyridin-4-yl)phenyl)ethene; HIPA = (5-hydroxyisophthalic acid)) with a high fluorescence quantum yield of 90.1%. The activated 1 exhibits high thermal stability and strong fluorescence in a methanol suspension. The fluorescence of activated 1 can be much more efficiently quenched by trans-dimethyl-2-butenedioate and trans-2-butene-1,4-diol than cis-dimethyl-2-butenedioate and cis-2-butene-1,4-diol, which enables it to differentiate these cis/trans isomers. This interesting LMOF could be a new type of fluorescence sensor to effectively detect cis/trans isomers.

A highly luminescent entangled metal-organic framework based on pyridine-substituted tetraphenylethene for efficient pesticide detection.

A novel pillared-layered entangled luminescent metal-organic framework [Zn2(bpdc)2(BPyTPE)] (1) (BPyTPE = (E)-1,2-diphenyl-1,2-bis(4-(pyridin-4-yl)phenyl)ethene) has been designed and constructed. The solvent-free 1 exhibits strong blue-green emission with an excellent fluorescence quantum yield of 99% and provides a facile and reversible method to sensitively and quantitatively detect trace pesticide of 2,6-dichloro-4-nitroaniline.

Screening of thrombin inhibitors from phenolic acids using enzyme-immobilized magnetic beads through direct covalent binding by ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry.

Thrombin was immobilized on dynabeads®M-270 epoxy by direct covalent binding method for the first time. The enzyme coated magnetic beads were combined with ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry technique to establish a simple, rapid and reliable approach for screening thrombin inhibitors from Danshen preparation. The conjugation of thrombin to the magnetic beads was characterized using scanning electron microscope, transmission electron microscope and infrared spectroscopy, and the enzyme activity was determined by the analysis of enzyme-bead ratio and peak areas of target compounds. Several factors including amount of magnetic beads, type of elution solvent, incubation temperature and time were optimized. Additionally, two thrombin-bound compounds (protocatechuic aldehyde and salvianolic acid C) in Danshen injection were validated by conventional inhibitory assay and the IC50 values were 286.11 and 66.09µg/mL, respectively. Our findings suggested that the proposed method was efficient in screening active compounds from medicinal plants.

Extraction and enrichment of natural pigments from solid samples using ionic liquids and chitosan nanoparticles.

A green and economical method for the extraction and preconcentration of natural pigments (curcumin, demethoxycurcumin and bisdemethoxycurcumin) was developed using ultrasound-assisted extraction combined with dispersive micro solid-phase extraction. In this work, Ionic liquids (ILs) were used for the pre-extraction of natural pigments. The pure chitosan nanoparticles (CS NPs) were then used as a sorbent for the microextraction mode. The method involves the use of ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry. Operating parameters influencing the performance of extraction steps such as type and concentration of ILs, concentration of CS NPs, type of elution solvent, agitation time and pH of sample-extracting solution were investigated. Under the optimum conditions, the proposed method exhibited a low detection limit in the range of 0.11-0.36ng/mL at S/N=3, and good linearities with coefficients of determination (R(2)) higher than 0.9990. The recoveries of turmeric samples were ranging from 90.45% to 105.04% for the three studied curcuminoids with SD of 3.27-6.58. The experimental results indicated that the ILs and CS NPs were the promising materials for the extraction and enrichment of target curcuminoids from complex solid samples.

Homochiral metal phosphonate nanotubes.

A new type of homochiral metal-organic nanotubular structures based on metal phosphonates are reported, namely, (R)- or (S)-[M(pemp)(H2O)2][M = Co(II) (1), Ni(II) (2)] [pemp(2-) = (R)- or (S)-(1-phenylethylamino)methylphosphonate]. In these compounds, the tube-walls are purely inorganic, composed of metal ions and O-P-O bridges. The cavity of the nanotube is hydrophilic with one coordination water pointing towards the center, while the outer periphery of the nanotube is hydrophobic, decorated by the phenylethyl groups of pemp(2-). The thermal stabilities, adsorption and proton conductivity properties are investigated.

A luminescent metal-organic framework constructed using a tetraphenylethene-based ligand for sensing volatile organic compounds.

By using a tetraphenylethene (TPE)-based ligand, tetrakis[4-(4-carboxyphenyl)phenyl]ethene (H4TCPPE), a porous metal-organic framework [Zn2(TCPPE)] (1) is synthesized, which exhibits strong fluorescence and is capable of gas adsorption and sensing volatile organic compounds.

Bis[(1S,1'S)-1,1'-(4-amino-4H-1,2,4-triazole-3,5-di-yl)diethanol-κN]bis-(nitrato-κO)zinc.

In the title homochiral mononuclear compound, [Zn(NO(3))(2)(C(6)H(12)N(4)O(2))(2)], the Zn(II) atom is located on a twofold rotation axis and coordinated by two N atoms from two ligands and two O atoms from two NO(3) (-) anions, adopting a distorted tetra-hedral coordination geometry. The compound is enanti-omerically pure and corresponds to the S diastereoisomer, with the optical activity originating from the chiral ligand. In the crystal, mol-ecules are connected into three-dimensional supra-molecular networks through O-H⋯O, O-H⋯N and N-H⋯O hydrogen bonds.

Homochiral zinc phosphonates with layered and open framework structures using polycarboxylate as second linkers.

Reactions of zinc sulfate and (R)- or (S)-(1-phenylethylamino)methylphosphonic acid (pempH(2)) in the presence of 1,4-benzenedicarboxylic acid (H(2)bdc) result in homochiral enantiomers (R)- and (S)-[Zn(4)(pempH)(4)(bdc)(2)].2H(2)O (). When H(2)bdc is replaced by 1,2,4,5-benzenetetracarboxylic acid (H(4)btec), enantiomers (R)- and (S)-[Zn(3)(pempH)(2)(btec)(H(2)O)(2)].H(2)O () are obtained. Compounds have a layer structure in which the chiral inorganic double chains, made up of corner-sharing {ZnO(4)} and {PO(3)C} tetrahedra, are connected by bdc(2-). While in compounds , chiral chains of zinc phosphonate are each connected to their four equivalent neighbors through btec(4-) linkages, resulting in an open framework structure. All these compounds are optically active, exhibiting second harmonic generation (SHG) responses 0.2 or 0.8 times that of urea.

Metal phosphonates based on (4-carboxypiperidyl)-N-methylenephosphonate: in situ ligand cleavage and metamagnetism in Co3(O3PCH2-NHC5H9-COO)2(O3PCH2-NC5H10)(H2O).

Hydrothermal reaction of (4-carboxypiperidyl)-N-methylenephosphonic acid (4-cpmpH3) and zinc sulfate results in compound Zn(O3PCH2-NHC5H9-COO) (). It has a pillared layered structure in which the inorganic layers made up of corner-sharing {CPO3} and {ZnO4} tetrahedra are connected by the organic groups. When cobalt sulfate is allowed to react with 4-cpmpH3 under similar conditions, a proportion of the ligands undergo decarboxylation, leading to the formation of a novel mixed ligated compound Co3(O3PCH2-NHC5H9-COO)2(O3PCH2-NC5H10)(H2O) (). Compound also shows a pillared layered structure with the topology of the inorganic layer similar to that of . The CoII ions in are all tetrahedrally coordinated. Significant difference between the two structures lies in the packing of the layers, e.g....AAA... in while ...AABAAB... in . More interestingly, compound behaves as a metamagnet at low temperature. The critical field is 40.1 kOe at 1.8 K.

Homochiral lanthanide phosphonates with brick-wall-shaped layer structures showing chiroptical and catalytical properties.

Based on enantiopure S- or R-(1-phenylethylamino)methylphosphonic acid (pempH(2)), homochiral lanthanide phosphonates (S)-[Ln(pempH)(NO(3))(2)(H(2)O)(2)] (S-Ln) and (R)-[Ln(pempH)(NO(3))(2)(H(2)O)(2)] (R-Ln) (Ln = Eu, Tb, Ho) are obtained successfully. All six compounds are isostructural, showing chiral brick-wall-shaped layer structures. They are all optically active, exhibiting second harmonic generation responses 0.7 times that of urea. The Eu and Tb compounds display strong red and green luminescent properties, respectively, with long luminescent lifetimes at the level of milliseconds. The catalytic properties of the dehydrated S-Tb are studied.

Polymorphism in homochiral zinc phosphonates.

This paper reports four homochiral zinc phosphonates, alpha-(S)-[Zn 2(pemp)(pempH)Cl] (1), alpha-(R)-[Zn 2(pemp)(pempH)Cl] (2), beta-(S)-[Zn 2(pemp)(pempH)Cl] (3), and beta-(R)-[Zn 2(pemp)(pempH)Cl] (4) [pempH 2 = (1-phenylethyl)amino]methylphosphonic acid]. Both 1 and 2 are enantiomers, crystallizing in an orthorhombic P2(1)2(1)2(1) space group, while 3 and 4 are polymorphic phases of 1 and 2, respectively, crystallizing in a monoclinic P2(1) space group. The polymorphism is induced by temperature or additional organic molecules.

A novel three-dimensional cadmium(II) coordination polymer incorporating 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene and thiocyanate.

In the title complex, poly[cadmiumII-mu2-1,4-bis(1,2,4-triazol-1-ylmethyl)benzene-di-mu2-thiocyanato], [Cd(NCS)2(C12H12N6)]n, the CdII atom lies on an inversion centre in a distorted octahedral environment. Four N atoms from the thiocyanate and 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene (bbtz) ligands occupy the equatorial positions, and two S atoms from symmetry-related thiocyanate ligands occupy the axial positions. The benzene ring of the bbtz ligand lies about an inversion centre. Single thiocyanate bridges link the CdII atoms into two-dimensional sheets containing novel 16-membered [Cd4(mu-NCS-N:S)4] rings. The bbtz ligands further link these two-dimensional sheets into an unprecedented covalent three-dimensional network for the cadmium-thiocyanate system.

A novel two-dimensional network cadmium(II) coordination polymer containing one 1,4-bis(1,2,4-triazol-1-yl)butane and double dicyanamide bridges.

In the crystal structure of the title complex, poly[mu-1,4-bis(1,2,4-triazol-1-yl)butane-di-mu-1,5-dicyanamido-cadmium(II)], [Cd(C2N3)2(C8H12N6)]n or [Cd(dca)2(btb)]n, where dca is dicyanamide and btb is 1,4-bis(1,2,4-triazol-1-yl)butane, each Cd(II) atom occupies a center of symmetry and is in a six-coordinated distorted octahedral environment. Four N atoms from four dca ligands fill the equatorial positions, and two N atoms from two btb ligands occupy the axial positions. The dca ligands adopt an end-to-end coordination mode and link the Cd(II) atoms to form a 12-membered Cd(dca)2Cd ring, and neighboring rings extend along the b axis to form a [Cd(dca)2]n chain. The btb ligands, acting as bridging bidentate ligands, link the Cd(II) atoms of adjacent one-dimensional [Cd(dca)2]n chains, forming a rhombic two-dimensional network.

A novel three-dimensional copper(II) coordination polymer with 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene and thiocyanate.

In the title complex, poly[copper(II)-di-2-thiocyanato-2-1,4-bis(1,2,4-triazol-1-ylmethyl)benzene], [Cu(NCS)2(C12H12N6)]n, the CuII atom lies on an inversion centre in a tetragonally distorted octahedral environment. Four N atoms from thiocyanate and 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene (bbtz) ligands fill the equatorial positions, and S atoms from symmetry-related thiocyanate ligands fill the axial positions. The benzene ring of the bbtz ligand lies about an inversion centre. Single thiocyanate bridges link the CuII atoms into two-dimensional sheets containing an unprecedented 16-membered [Cu4(-NCS-N:S)4] ring. The bbtz ligands further link the two-dimensional sheets into a three-dimensional network.