Guest-Facilitated Heteroleptic Assembly of Helical Anionocages Enables Reversible Chirality Modulation.

We report a novel strategy for reversible modulation of the supramolecular chirality based on guest-facilitated heteroleptic assembly of helical anionocages. Two triple-stranded helical anionocages including a chiral cage 1 (A2 L1 3 ) and a crown ether functionalized achiral cage 2 (A2 L2 3 ) were synthesized by anion coordination of bis-monourea-based ligands and PhPO3 2- . Both cages exhibited favorable binding with tetraethylammonium TEA+ and cobaltocenium Cob+ (endo-guest, bound in the cavity). Additionally, cage 2 could reversibly release and recapture the guests through binding the exo-guest potassium ions (K+ ) in the crown ethers and subsequent removal of the K+ by [2,2,2]-cryptand. The circular dichroism (CD) spectrum of cage 1 was not significantly affected by guest encapsulation or mixing with the "empty" cage 2. However, in the presence of both cage 2 and an endo-guest/exo-guest, the Cotton effects were reversed at 391 nm and significantly enhanced at 310 nm. This observation was attributed to the guest-facilitated formation of heteroleptic cages that enabled effective chirality transfer from the chiral to the achiral ligands. The CD changes induced by K+ could be fully reversed by removing it with [2,2,2]-cryptand. Sequential addition and removal of K+ allowed reversible modulation of the chirality for at least 10 cycles without significant attenuation.

Nitrogen-Doped and Surface Functionalized CDs: Fluorescent Probe for Cellular Imaging and Environmental Sensing of ClO.

A novel nitrogen doped and surface functionalized fluorescent CDs (T1) was synthesized by one-step and green hydrothermal method, which exhibits a satisfactory fluorescence quantum yield and a series of admirable features such as good aqueous solubility, narrow particle size distribution, resistance to photobleaching as well as excitation-dependent behavior. Benefitting from above merits, T1 can be employed to serve as an outstanding sensing platform for sensitive and accurate detection of ClO- by remarkable fluorescence "on-off" process with rapid and anti-interference. More notably, the good biocompatibility and photostability can ensure enormous bioimaging potential and successful application of T1 in monitoring of exogenous ClO- in MG-63 cells. Meanwhile, T1 can also be regarded as a filter paper sensor providing a convenient and efficient analyzing technology for monitoring of free residual chlorine in practical environmental samples. All these results demonstrate that there exists promising possibility for practical applications of T1 in bioimaging systems and environmental monitoring.

Hierarchical Self-Assembly of a Pyrene-Based Discrete Organoplatinum(II) Double-Metallacycle with Triflate Anions via Hydrogen Bonding and Its Tunable Fluorescence Emission.

Hierarchical self-assembly of discrete organoplatinum(II) metallacycles has attracted considerable attention. However, the exact assembly mechanism involving non-covalent interactions has limited the formation and application of self-assembly due to the dynamics of platinum metallacycles. Herein, we report the hierarchical self-assembly of a pyrene-based discrete organoplatinum(II) double-metallacycle that takes advantage of heteroligation-coordination-driven self-assembly and triflate anions' hydrogen bonding, which is extended into a 3-D supramolecular framework by the hydrogen-bonding interactions involving triflate anions. Furthermore, the assembled system displays tunable fluorescence emission and enhanced solid emission. The studies herein disclosed pave the way to prepare platinum(II) metallacycle-based supramolecular functional materials.

Diterpenoids from Torreya grandis and their cytotoxic activities.

Eight previously undescribed diterpenoids, along with eleven previously reported analogues, were obtained from the supercritical CO2 extracts of Torreya grandis aril. The structures of these compounds were elucidated based on HRESIMS, NMR, ECD, and single-crystal X-ray diffraction data. In the MTT assay, compound 18 exhibited significant inhibitory effects on two human colon cancer cell lines, HT-29 and HCT 116 cells, with IC50 values of 7.37 µM and 6.55 µM, respectively. It was found that compound 18 induced apoptosis and significantly inhibited the migration of HCT 116 colon cancer cells in a concentration-dependent manner.

Influences of Four Kinds of Surfactants on Biodegradations of Tar-Rich Coal in the Ordos Basin by Bacillus bicheniformis.

The biodegradation of tar-rich coal in the Ordos Basin was carried out by Bacillus licheniformis (B. licheniformis) under actions of four kinds of surfactants, namely, a biological surfactant (Rh), a nonionic surfactant (Triton X-100), an anionic surfactant (LAS), and a cationic surfactant (DTAB). The biodegradation rates under the actions of Triton X-100, LAS, Rh, DTAB, and the control group (without surfactant) were 59.8%, 54.3%, 51.6%, 17.3%, and 43.5%, respectively. The biodegradation mechanism was studied by examining the influences of surfactants on coal samples, bacteria, and degradation products in the degradation process. The results demonstrated that Rh, Triton X-100, and LAS could promote bacterial growth, while DTAB had the opposite effect. Four surfactants all increased the cell surface hydrophobicity (CSH) of B. licheniformis, and Triton X-100 demonstrated the most significant promotion of CSH. The order of improvement in microbial cell permeability by surfactants was DTAB > TritonX-100 > LAS > Rh > control group. In the presence of four surfactants, Triton X-100 exhibited the best hydrophilicity improvement for oxidized coal. Overall, among the four surfactants, Triton X-100 ranked first in enhancing the CSH of bacteria and the hydrophilicity of oxidized coal and second in improving microbial cell permeability; thus, Triton X-100 was the most suitable surfactant for promoting B. licheniformis's biodegradation of tar-rich coal. The GC-MS showed that, after the action of Triton X-100, the amount of the identified degradation compounds in the toluene extract of the liquid product decreased by 16 compared to the control group, the amount of dichloromethane extract decreased by 6, and the amount of ethyl acetate extract increased by 6. Simultaneously, the contents of alkanes in the extracts of toluene and dichloromethane decreased, lipids increased, and ethyl acetate extract exhibited little change. The FTIR analysis of the coal sample suggested that, under the action of Triton X-100, compared to oxidized coal, the Har/H and A(CH2)/A(CH3) of the remaining coal decreased by 0.07 and 1.38, respectively, indicating that Triton X-100 enhanced the degradation of aromatic and aliphatic structures of oxidized coal. Therefore, adding a suitable surfactant can promote the biodegradation of tar-rich coal and enrich its degradation product.

Three water-soluble acylhydrazone tetranuclear transition metal complexes: Crystal structures, DNA/BSA interactions and cytotoxicity studies.

2-acetylpyridine-4-chloropyridine-2­carbonyl hydrazone (C13H11ClN4O, HL) and its three water-soluble tetranuclear complexes [Cu4(NO3)2(L)4]·(NO3)2 (1), [Co4(NO3)2(H2O)(C2H5OH)(L)4]·(NO3)2 (2) and [Zn4(NO3)2(H2O)(C2H5OH)(L)4]·(NO3)2 (3) were synthesized and characterized showing that 1-3 were all tetranuclear complexes. The interactions of HL, 1-3 with calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) were explored using ultraviolet-visible (UV-Vis) titration, fluorescence spectroscopy, microcalorimetry and molecular docking techniques. The UV-Vis spectroscopy measurements showed that complexes 1-3 could strongly bind to CT-DNA by the intercalation mode, while HL interacted with CT-DNA through groove binding. From the fluorescence spectroscopy results, the interaction between HL, 1-3 and BSA was a static quenching procedure, in which complexes 1-3 had two binding sites near Trp residues of BSA while HL only had one. The microcalorimetric studies revealed that the interactions of HL and 1-3 to CT-DNA/BSA were all endothermic and the duration of each interaction was all less than 30 min. The in silico molecular docking illustrated intermolecular interactions of 1-3 binding with DNA/BSA included hydrogen bond, halogen bond, hydrophobic and electrostatic interactions. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay indicated that complex 1 possessed better cytotoxicity against HeLa, A549, MCF7 and HCT-116 than cisplatin and could be used as an alternative anticancer drug.

Nitrogen-doped carbon quantum dots as fluorescent nanosensor for selective determination and cellular imaging of ClO.

The carbon nanomaterial based fluorescent probes have been widely applied in biological imaging. In the current research, we propose an interesting strategy for selective sensing of hypochlorite (ClO-) by a water-soluble and highly fluorescent nanosensor based on the N-doped carbon quantum dots (CDs) which was fabricated by a facile and environmental friendly hydrothermal approach from polyvinyl pyrrolidone, L-arginine and tryptophan. The structural characteristics of the probe were measured by multitudinous methods which proved the nanometer spherical structure of the probe and the successfully N-doping. Fluorescent investigation demonstrated that the probe is not only highly stable under interferences of pH, ionic strength, and irradiation, but also significantly selective toward ClO- amongst a variety of attractive bioactive species through the fluorescent quenching process which was correlative with the concentration of ClO- and linearly in the range of 0.1-50 µmol·L-1 with the sensitivity of 0.03 µmol·L-1. The probe can also be further illustrated in a prospective application for determination of ClO- in environmental water through both solution response and filer paper sensing. Moreover, the positive biocompatibility and ignorable cytotoxicity made the probe a promising effective agent for detection and visualizing ClO- in living cells which can facilitate the understanding the oxidative stress from the overexpressing ClO-.

Study of the Influence of Biodegradation on Coal Micro-Nano Pore Structure Using Low-Temperature N2 Adsorption.

An experimental study of biodegradation of Shenmu coal was carried out by using Ochrobactrum cytisi, Novospingobium naphthalenivorans, Alcaligenes faecalis and Pseudomonas fluorescens. The micro-nano pore structure of coal samples before and after biodegradation was studied by low-temperature N2 adsorption. For biodegraded coal, the results showed that micropores and mesopores are primarily open pores with good connectivity, including parallel plate pores and cylinder pores with two open ends; the specific surface area of biodegraded coal decreased from 2.2174 m²/g to 1.6255˜2.0537 m²/g, and the pore size of the coal biodegraded by the four bacteria decreased following biodegradation from 250 nm to 170˜200 nm, which may be due to collapse of the coal structure due to the bacterial degradation. Coal biodegradation by the dominant bacterium P. fluorescens led to a diminished mesopore size and an increased number of smaller mesopores, with the smaller mesopores gradually taking on dominant roles.

Sandwich phosphate complexes of macrocyclic tris(urea) ligands and their rotation around the anion.

Four heteroditopic macrocyclic ligands incorporating both anion coordination sites (tris-urea units) and a cation binding fragment (polyether) were designed for possible application in molecular devices. Sandwich-type phosphate complexes were formed, which display a reversible rotation around the anion upon protonation/deprotonation of phosphate and binding of the cation (Emim(+)).

Sulfate encapsulation in a metal-assisted capsule based on a mono-pyridylurea ligand.

A sulfate-encapsulating complex, [Cu(1)L(6)]·3[Cu(2)L(2)(DMF)(4)](SO(4))(4) (1, L = N-(1-naphthyl)-N'-(3-pyridyl)urea) is synthesized in which two C(3)-clefts of the octahedral complexes interdigitate to form a cavity to encapsulate the sulfate ion by six urea groups.

A fully complementary, high-affinity receptor for phosphate and sulfate based on an acyclic tris(urea) scaffold.

A fully complementary tris(urea) receptor for phosphate and sulfate anions has been developed by mimicking the scaffold of terpyridine which shows very high affinities and selectivities toward the tetrahedral anions.