Luminescence turn-on sensor for the selective detection of trace water and methanol based on a Zn(ii) coordination polymer with 2,5-dihydroxyterephthalate.

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.

Nanoscale carbon dot-embedded metal-organic framework for turn-on fluorescence detection of water in organic solvents.

An easy-to-use, highly selective, and real-time organic solvent quality assessment is desirable to detect water contamination in organic solvents. Herein, a one-step procedure using ultrasound irradiation was used for encapsulating nanoscale carbon dots (CDs) into metal-organic framework-199 (HKUST-1) to form CDs@HKUST-1 composite. The CDs@HKUST-1 exhibited very weak fluorescence due to photo-induced electron transfer (PET) from the CDs to the Cu2+ centers, acting as a fluorescent sensor in its off-state. The designed material can detect and discriminate water from other organic solvents, driven by turn-on fluorescence. This highly sensitive sensing platform could be applied for the detection of water in ethanol, acetonitrile, and acetone with wide linear detection ranges of 0-70% v/v, 2-12% v/v, and 10-50% v/v and limits of detection of 0.70% v/v, 0.59% v/v, and 1.08% v/v, respectively. The detection mechanism is attributed to the interruption of the PET process due to the release of fluorescent CDs after treatment with water. A smartphone-based quantitative test was successfully developed to monitor the water content in organic solvents utilizing CDs@HKUST-1 and a phone color processing application, thus making it possible to develop an on-site, real time and easy-to-use sensor for water detection.

Multifunctional fluorescent Eu-MOF probe for tetracycline antibiotics and dihydrogen phosphate sensing and visualizing latent fingerprints.

The contamination of tetracycline antibiotics and dihydrogen phosphate (H2PO4 -) in food and the environment is one of the major concerns for human health. Herein, a water-stable carboxyl-functionalized europium metal-organic framework (Eu-MOF) was prepared and demonstrated, for the first time, as a dual-responsive fluorescent sensor of tetracycline antibiotics (oxytetracycline (OTC), tetracycline (TC), and doxycycline (DOX)) and H2PO4 - via fluorescent turn-on and turn-off, respectively. Eu-MOF presents a sensitive and selective detection of OTC with a rapid response time (1 min) and good anti-interference ability. The limits of detection (LODs) of 78 nm, 225 nm, and 201 nM were achieved for OTC, TC, and DOX, respectively. Coordination and hydrogen bonding led to energy and electron transfer from the TC to the MOF, contributing to the fluorescent enhancement mechanism. Moreover, Eu-MOF can effectively detect H2PO4 - via fluorescence turn-off with a LOD of 0.70 µM. The interactions between H2PO4 - and MOF interrupt the energy transfer from ligand to MOF, leading to fluorescence quenching. In addition, Eu-MOF was successfully applied to determine OTC and H2PO4 - in real samples, obtaining satisfactory recoveries and RSDs. More fascinating, Eu-MOF could be utilized to develop latent fingerprints on various surfaces, providing well-defined fluorescent fingerprint details in which the sweat pores can be seen with the naked eye.

Dual stimuli-responsive phosphorescence of a Pb(II) coordination polymer to acidic vapors and thermal treatment.

We present a new intensely phosphorescent Pb(II) coordination polymer (1) containing a heteroatomic ligand. It has a quantum yield of 21.62% and a lifetime of 25.46 µs. The naked-eye solid-state photoluminescence of 1 significantly changes in response to acidic vapors and thermal treatment, indicating the coexistence of acidochromic and thermochromic luminescence.

Isopimarane-type diterpenoids from the rhizomes of Kaempferia galanga L. and their biological activities.

Fourteen isopimarane diterpenoids (1-14) were isolated from the rhizomes of Kaempferia galanga, including four new compounds (1-4). The isolated secondary metabolites were identified through analysis of spectroscopic (1 D and 2 D NMR) and mass spectrometric data, together with X-ray diffraction studies. Compounds 4-5, 7-11, and 13 showed strong antimalarial activities, with IC50 values in the range of 1.46-3.99 µg/mL. Moreover, compounds 4, 5, 8, and 12 showed cytotoxicity against KB cell line with IC50 values in the range of 6.13-38.2 µg/mL, while compounds 4, 5, and 12 showed cytotoxicity against MCF-7 cell line with IC50 values in the range of 11.75-47.4 µg/mL. Eventually, the isolated compounds were screened against six bacterial strains and Mycobacterium tuberculosis, demonstrating weak to moderate activities.

Hypoxylonone, a new oxa-bridged seven-membered ring analog from fungus Hypoxylon cf. subgilvum SWUF15-004.

A new oxa-bridged seven-membered ring analog, hypoxylonone (1), and thirteen known compounds (2-14) were isolated from fungus Hypoxylon cf. subgilvum SWUF15-004. The structures were elucidated by the analysis of spectroscopic (IR, 1 D and 2 D NMR), HRESIMS and X-ray diffraction (MoKα) data. Several isolated compounds were evaluated for cytotoxicity against four human cancer cell lines (HeLa, HT29, MCF-7, A549). Compound 1 exhibited weak inhibitory effects of the nitric oxide production in RAW264.7 cells. Compounds 8 and 9 exhibited slight cytotoxicity.

Simultaneous Occurrence of Vapochromism and Vapoluminescence in Formaldehyde-Responsive Amino-Functionalized Copper(I) Polymorphic Coordination Polymers.

The use of vapor-responsive chromic materials in sensing applications for the detection of harmful volatile organic chemicals is rapidly expanding. Herein, four new amino-functionalized Cu(I) coordination polymers of [CuI(pyt-NH2)]n (1) and (2) and [CuSCN(pyt-NH2)]n (3) and (4) (where pyt-NH2 = 2-amino-5-(4-pyridinyl)-1,3,4-thiadiazole) were successfully synthesized. Single-crystal X-ray diffraction analysis reveals that 1 and 2 are iodo-based polymorphs, while 3 and 4 are thiocyanato-based polymorphs. They possess densely diverse crystalline architectures decorated by uncoordinated amino groups as a binding site. Also, 1-4 show a variety of color and luminescence based on the structural diversity. Remarkably, 1 and 2 undergo the change of color and naked-eye solid-state luminescence in response to formaldehyde (FA) vapor, demonstrating simultaneous vapochromism and vapoluminescence. The chromic Cu(I) coordination polymers in this work present for the first time dual-mode vapochromism and vapoluminescence in a highly selective response to FA vapor. The responsive mechanism has been clarified by Fourier transform infrared spectroscopy (FT-IR), electrospray ionization mass spectrometry (ESI-MS), 1H nuclear magnetic resonance (NMR), powder X-ray diffraction (PXRD), and luminescence lifetime measurements, which reveal carbinolamine formation via the specific reaction between FA and the active amino groups of coordinated pyt-NH2. The carbinolamine formation can trigger the structural transformation of 1 and 2, leading to the concurrently selective vapochromism and vapoluminescence induced by FA vapor.

pH modulated luminescent switching and discriminative detection of amino acid based on metal-organic framework.

The detection of glutamic (Glu) or aspartic (Asp) acids is vital for human nutrition and diagnosis of disease. Herein, the dht ligand containing hydroxy group (-OH) is used to design and synthesize a 2D luminescent [Cd2(idc)(dht)(H2O)4] (1); H2idc = 4,5-imidazoledicarboxylic acid and H2dht = 2,5-dihydroxyterephthalic acid for sensing amino acids. The compound 1 can discriminatively detect Asp and Glu among other amino acids through blue-shifted emission (yellow → green). The dual sensing mechanism may be attributed to the intermolecular excited-state proton transfer between MOF and water to produce keto form along with the subsequent switching of keto form to enol form by protonation causing the increased band gap energy. This material can serve several benefits in terms of high selectivity, fast response (30s), good reproducibility and low LOD value of 11.34 µM which is less than the harmful concentration of Glu for human health (>400 µM). In addition, 1 shows the broad range detection of Glu covering in safe and unsafe levels. For on-site detection of Glu, MOF-based paper is devised and can be applied through color-scanning application in smartphone. Besides, this sensor can serve to detect Glu in real samples with good recovery.

Coexistence of Naked-Eye Mechanochromism, Vapochromism, and Thermochromism in a Soft Crystalline Layered Nickel(II) Coordination Polymer.

Chromic materials have the potential to be used in a variety of applications, including memory devices and sensors. Despite fact that stimuli-responsive chromic materials have been widely reported to date, fabricating chromic materials that can be responsive to multiple external stimuli remains a challenge. Herein, a new multistimuli responsive chromic coordination polymer of {[Ni(pzt)2(H2O)2](H2O)(DMF)}n (1); Hpzt = 5-(3-pyridyl)-1,3,4-oxadiazole-2-thiol, was successfully synthesized. Single-crystal X-ray diffraction analysis revealed that 1 exhibits a soft crystalline 3-dimenional (3D) supramolecular framework generated by weakly interlayered stacking interactions between 2D coordination polymers. Compound 1 revealed unprecedented naked-eye mechanochromism, vapochromism, and thermochromism in response to multiple external stimuli including manual grinding, amine and alcohol vapors, and heat, respectively. The chromism related to the structural feature was clarified by SC-XRD, PXRD, TGA, elemental analysis, and spectroscopic techniques.

Anti-inflammatory and anti-proliferative activities of chemical constituents from fungus Biscogniauxia whalleyi SWUF13-085.

The fungus Biscogniauxia whalleyi SWUF13-085 from the Graphostomataceae family was studied for potential anti-inflammatory and anticancer agents. A diverse array of natural products was identified. Six of which were undescribed compounds, including xylariterpenoids L-N, (1R,2S,6R,7S)-1,2-dihydroxy-α-bisabolol, 6-[(1R)-1-hydroxy-1-methyl-2-propenyl]-4-methoxy-3-methyl-2H-pyran-2-one and (1R*,4S*,5S*,7S*,10R*)-guaia-11 (12)-en-7,10-diol. Several of the isolated compounds such as bergamotene, guaiane and phthalide derivatives showed activity in both the inhibition of nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage cells with IC50 values in the range of 2.48-10.82 µg/mL and anti-proliferation against HeLa cells with IC50 values in the range of 8.64-31.16 µg/mL. While compounds such as cerebrosides A and C only exhibited inhibitory effects on NO production with IC50 values in the range of 4.45-10.28 µg/mL.

ent-Clerodane diterpenoids from the stems of Croton krabas.

The first phytochemical investigation from the stems of Croton krabas resulted in the isolation of three new ent-clerodane diterpenoids, crotonkrabases A-C (1-3), along with two known compounds, 12-oxohardwickiic acid (4) and crotonpyrone B (5). Their structures were elucidated using extensive spectroscopic methods. The structure of 3 was unambiguously proven by X-ray crystallography. Furthermore, the absolute configurations of compounds 1-3 were identified by NOESY and the comparison of their experimental ECD spectra with those of calculated ECD spectra reported in the literature. Compounds 1, 2, and 5 showed antibacterial activities against two Gram-positive bacteria (Bacillus cereus and Bacillus subtilis); whereas compound 4 exhibited weak antibacterial against B. cereus. In addition, compound 4 showed potent α-glucosidase inhibitory activity, which was lower than the reference standard acarbose.

Synthesis, characterization and anticancer activity of Fe(II) and Fe(III) complexes containing N-(8-quinolyl)salicylaldimine Schiff base ligands.

A series of Fe(II) complexes (1-4) and Fe(III) complexes (5-8) from Fe(II)/(III) chloride and N-(8-quinolyl)-X-salicylaldimine Schiff base ligands (Hqsal-X2/X: X = Br, Cl) were successfully synthesized and characterized by spectroscopic (FT-IR, 1H-NMR), mass spectrometry, thermogravimetric analysis (TGA), and single crystal X-ray crystallographic techniques. The interaction of complexes 1-8 with calf thymus DNA (CT-DNA) was determined by UV-Vis and fluorescence spectroscopy. The complexes exhibited good DNA-binding activity via intercalation. The molecular docking between a selected complex and DNA was also investigated. The in vitro anticancer activity of the Schiff base ligands and their complexes were screened against the A549 human lung adenocarcinoma cell line. The complexes showed anticancer activity toward A549 cancer cells while the free ligands and iron chloride salts showed no inhibitory effects at 100 µM. In this series, complex [Fe(qsal-Cl2)2]Cl 6 showed the highest anticancer activity aginst A549 cells (IC50 = 10 µM). This is better than two well-known anticancer agents (Etoposide and Cisplatin). Furthermore, the possible mechanism for complexes 1-8 penetrating A549 cells through intracellular ROS generation was investigated. The complexes containing dihalogen substituents 1, 2, 5, and 6 can increase ROS in A549 cells, leading to DNA or macromolecular damage and cell-death induction.

Sonochemical synthesis of a trinuclear Cu(ii) complex with open coordination sites for the differentiable optical detection of volatile amines.

A discrete trinuclear Cu(ii) complex, namely, [Cu3(pzdc)2(dpyam)2(H2O)4] (1) (H3pzdc = pyrazole-3,5-dicarboxylic acid, dpyam = 2,2'-dipyridylamine) was simply synthesized by the sonochemical process and structurally characterized. The single-crystal X-ray diffraction analysis revealed that three adjacent Cu(ii) centers are linked via two bridging pzdc ligands to form a trinuclear Cu(ii) unit. Each trinuclear Cu(ii) unit contains open coordination sites with two trigonal bipyramidal Cu(ii) centers and one elongated octahedral geometry. Moreover, the open coordination site of 1 was occupied by a small molecule, leading to the guest-induced structural transformation with chromism that was verified by FT-IR, UV-vis diffuse reflectance spectra, elemental analysis, PXRD, and SEM techniques. Compound 1 exhibits color change along with structural transformation in methanol media and after the dehydration process. Also, 1 shows different color responses after exposure to different amine vapors. In addition, compound 1 was conveniently deposited onto a filter paper by a sonochemical method used as a portable test strip for the discriminative qualitative detection of amines.

Dual Function Based on Switchable Colorimetric Luminescence for Water and Temperature Sensing in Two-Dimensional Metal-Organic Framework Nanosheets.

A simple, rapid, highly selective, and real-time determination of water is urgently required for preventing danger from water contamination in materials. Herein, the excited-state proton transfer (ESPT) concept-based luminescent sensor [Cd2(2,5-tpt)(4,5-idc)(H2O)4] (1) (2,5-tpt = 2,5-dihydroxyterephthalic acid and 4,5-idc = 4,5-imidazoledicarboxylic acid) has been designed for discriminative detection via enol-keto tautomerism. To improve the sensitivity, two-dimensional (2D) nanosheets of 1 have been synthesized by top-down liquid ultrasonic exfoliation technology for sensing water in dimethylformamide, which lead to fast detection (<30 s), high selectivity, broad-range detection (0-50% v/v), and a low detection limit value (0.25% v/v). This sensor can serve dual sensing mechanisms along with a luminescent color change via shifted emission (green→yellow) in low water content and a turn-off method in high water content. For ease of use, the test-strip paper-based 2D nanosheets of 1 have been prepared and applied for water detection with long-term stability, pH stability, and good reusability. On-site water detection in real time can be evaluated using a smartphone color-scanning application for quantitative scanometric assays coupled with test-strip paper-based 2D nanosheets of 1. Also, 1 can be utilized for a colorimetric luminescent thermometer in the ranges of physiological and high temperature with good linearity and recyclability.

Sonochemical synthesis of microscale Zn(ii)-MOF with dual Lewis basic sites for fluorescent turn-on detection of Al3+ and methanol with low detection limits.

The effects of synthetic methods, modulator types, the content of the modulator, and reaction time on the size and morphology of a microscale Zn-MOF containing dual Lewis basic amino and carbonyl groups, namely [Zn(NH2-bdc)(4,4'-bpy)] {NH2-H2bdc = 2-amino-1,4-benzenedicarboxylic acid and 4,4'-bpy = 4,4'-bipyridine}, were systemically investigated. Uniform octahedral microparticles of Zn-MOF with an average size of 1.7 µm were obtained within an hour at ambient temperature under ultrasound irradiation using sodium acetate as a modulating agent. Interestingly, Zn-MOF has been demonstrated for the dual-functional fluorescent detection of Al3+ and methanol based on a fluorescent turn-on strategy. Very low detection limits (LODs) for Al3+ and methanol were achieved using microcrystalline Zn-MOF and reached 30 nM and 0.7% (v/v), respectively. In comparison to the larger size of the polycrystalline Zn-MOF, the microparticles obtained from the ultrasonic route exhibited an improvement in the detection sensitivity. The dual uncoordinated Lewis basic sites play an important role in the sensitivity and selectivity of the detection. Additionally, the fluorogenic change in the sensing process can be observed by the naked eye under UV-light, allowing preliminary on-field screening.

A Solid-State Luminescent Cd(II) Supramolecular Coordination Framework Based on Mixed Luminophores as a Sensor for Discriminatively Selective Detection of Amine Vapors.

A novel Cd(II) supramolecular coordination framework containing mixed functionalized luminophore ligands, namely, [Cd(AS)2(phen)2]EtOH or 1 (where AS = 4-aminosalicylate, phen = 1,10-phenanthroline, EtOH = ethanol), was successfully synthesized as a solid-state luminescent sensor for the detection of amine vapors. The single-crystal X-ray diffraction analysis revealed that 1 possesses a three-dimensional (3D) supramolecular framework enclosing ethanol molecule in the lattice. The supramolecular structure is well-stabilized by various noncovalent intermolecular interactions through functional groups of ligands. Compound 1 shows an intense yellow solid-state emission and displays a reversibly discriminative luminescent response to NH3 and ethylenediamine (EDA) vapors through very large blue-shifted luminescent spectra with distinguishable emission colors under UV light. This work reports the first time for selective luminescent sensing of NH3 and EDA vapors with considerably different emission color change. A sensing mechanism has been confirmed by density functional theory and time-dependent density functional theory calculations that agrees well with the experimental results. Also, 1 exhibits a good recyclability over five cycles for sensing of NH3 and EDA vapors.

Chemical constituents and cytotoxic activity from the wood-decaying fungus Xylaria sp. SWUF08-37.

A new cyclic pentapeptide, pentaminolarin (1), and a new cytochalasin, xylochalasin (2), along with thirteen known compounds (3-15) were isolated from the wood-decaying fungus Xylaria sp. SWUF08-37. The absolute configurations of 1 were determined by a combination of Marfey's method and TDDFT ECD calculation and the absolute configurations of 2 were established by TDDFT ECD calculation. Compound 12 showed moderate cytotoxicity against HeLa (IC50 = 19.60 µg/mL), HT29 (IC50 = 17.31 µg/mL), HCT116 (IC50 = 14.28 µg/mL), MCF-7 (IC50 = 15.38 µg/mL), and Vero (IC50 = 24.97 µg/mL) cell lines by MTT assay. Compounds 1 and 2 showed slight cytotoxicity against all tested cancer cell lines.

Sonochemical Synthesis of Carbon Dots/Lanthanoid MOFs Hybrids for White Light-Emitting Diodes with High Color Rendering.

Although lanthanoid metal-organic frameworks (Ln-MOFs) have been widely developed for white light-emitting diodes (WLEDs), the color rendering index (CRI) values are still lower than 80. To overcome this limitation, a series of CDs/Ln-MOFs hybrids, namely, CDs-2@Ln-MOF, CDs-3@Ln-MOF, and CDs-4@Ln-MOF containing blue-emitting CDs and yellow-emitting bimetallic [(Eu1.22Tb0.78(1,4-phda)3(H2O)](H2O)2 were prepared via sonication at room temperature to restrict the self-quenching of CDs in composite materials. The as-synthesized composite materials were investigated by Fourier transform infrared, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and photoluminescence. The luminescent color of the materials can be adjusted by varying the amount of CDs and excitation wavelengths. The resulting CDs-3@Ln-MOF achieved excellent CRI up to 93 with the ideal Commission International ed'Eclairage coordinate (0.334, 0.334) and appropriate correlated color temperature (CCT) (5443 K). In addition, the tunable multicolored luminescence based on single and bimetallic EuxTb2-x(1,4-phda)3(H2O)](H2O)2, x = 0, 0.73, 1.22, 1.57, 1.94, and 2, were applied as the luminescent security inks for anti-counterfeiting application through encoding/decoding and rewritable data.

Lithium-Templated Formation of Polyhedral Oligomeric Silsesquioxanes (POSS).

A coordination complex, lithium hepta(i-butyl)silsesquioxane trisilanolate (1; Li-T7), a stable intermediate in silsesquioxane (SQ) syntheses, was successfully isolated in 65% yield and found to be highly soluble in nonpolar solvents such as hexane. The structure of Li-T7 was confirmed by NMR, IR spectroscopy, matrix-assisted laser desorption ionization time-of-flight mass spectrometry, electrospray ionization mass spectrometry, and computational simulation, providing detailed elucidation of the intermolecular self-association of the SQ cage with a box-shaped Li6O6 polyhedron through strong coordination bonds. After acid treatment, Li-T7 undergoes lithium-proton cationic exchange, yielding hepta(i-butyl)silsesquioxane trisilanol (2; H-T7) quantitatively. The high yield of H-T7 seems to be influenced by Li-O bonding in the Li-T7 complex that affects the selective formation of hepta(i-butyl)silsesquioxane trisilanolate and the bulky i-butyl groups which may prevent decomposition or SQ cage-rearrangement even at reflux under alkaline conditions. Single-crystal X-ray crystallography confirms the presence of the dumbbell-shaped SQ partial cages through strong intermolecular hydrogen bonds. Interestingly, lowering the polarity of the reaction solution by adding dichloromethane results in formation of the cubic octa(i-butyl)silsesquioxane (3; T8) cage in a good yield (47%), which is isolated by crystallization from the reaction solution.

Spiroaxillarone A, a Symmetric Spirobisnaphthalene with an Original Skeleton from Cyanotis axillaris.

The first representative of a new type of spirobisnaphthalene with a previously unknown skeletal system, Spiroaxillarone A (1), was isolated from Cyanotis axillaris. The planar structure was determined through analysis of spectroscopic evidence, while electronic circular dichroism (ECD) calculations were used to determine its absolute configuration. The structure of 1 was further confirmed through X-ray diffraction studies of its tetrabromobenzoate derivative (1a). Spiroaxillarone A exhibited significant antimalarial activity against resistant Plasmodium falciparum (IC50 = 2.32 µM).