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Transition metal (TM) cations and clusters have been widely used to functionalize polyoxometalates (POMs) of tungsten, molybdenum and vanadium due to their acidic nature, which made them compatible with addendum TM cations. Together with the good understanding of their solution behavior, a number of TM-based POMs have been achieved, which exhibited potential applications in many fields. Comparably, fewer polyoxoniobates (PONs) were obtained due to the poor understanding of their solution behavior, and they could only exist in strong alkaline aqueous solutions, where most of the TM cations precipitate because of the formation of hydroxide or oxide. Recently, TM cations were introduced into PONs by protection of chelate organic ligands or via selection of alkaline-soluble TM cations. Further, lacunary POMs, composed of early TM cations, were used as polydentate ligands to isolate PONs, and they make the PON clusters stably exist in acidic solutions. The acidic nature of tungstoniobate (W–Nb) clusters allowed acid-soluble TM cations to directly functionalize the Nb–W clusters. This highlight focuses on discussing the roles of TM centers in constructing PON-based materials, including TM-cluster-containing PONs, TM–organic group-decorating PONs and niobate clusters isolated by lacunary POMs. This systematic compilation of TM-PON studies will reveal a promising direction for further functionalization of PONs, and it will disclose a richer and more diverse set of structures in PON chemistry.

Recently, high-entropy alloys (HEAs) have attracted much interest in the materials community, as they offer massive opportunities to observe new phenomena, explore new structure, and develop new materials. Particularly, it is attractive to prepare high-performance HEA coatings by laser-induced rapid solidification, which can be formed on the surface of components and parts in a variety of sizes and shapes with a lower cost in comparison with those bulk material fabrication methods. From the technical point of view, laser-induced rapid solidification could hamper the compositional segregation, improve the solubility in solid-solution phases, and lead to the strengthening effect by the grain refinement. This article reviews the recent work on the typical microstructural features and the mechanical and chemical properties in laser-induced rapidly solidified HEAs, and these data are compared with conventional Co- and Ni-based alloy coatings. The article concludes with suggestions for future research and development in HEAs, from considerations of their characteristic properties.

The red emitting phosphors ZnBi2B2O7:xEu3+ (x = 0-0.035) are prepared by reactive sintering of Eu2O3, ZnO, Bi2O3, and H3BO3 in air (1.

Mycobacterium protein tyrosine phosphatase B (mPTPB) is essential for the survival and persistence of Mycobacterium in the host. Thus small molecule inhibitors of mPTPB are potential anti-TB agents. We developed an efficient organocatalytic multicomponent reaction (MCR) between pyrrole, formaldehyde and aniline, affording a potent and selective mPTPB inhibitor with an IC50 value of 1.5 μM and >50-fold specificity. Our studies provide a successful example of using organocatalysis as a discovery tool for the acquisition of PTP inhibitors.

A ligand-free CuI-catalyzed cascade C–S and C–N cross coupling of (hetero)aryl ortho-dihalides and ortho-aminobenzenethiols has been developed, and various phenothiazines were synthesized with excellent regioselectivity. A possible mechanism is proposed for the cascade coupling.

The novel natural product xyloallenoide A, isolated from the marine mangrove endophytic fungus from the South China Sea, and its diastereoisomer xyloallenoide A1, which contain N-methyl-substituted amino acids, were synthesized. The absolute configurations of the amino acid units of xyloallenoide A were finally confirmed to be L-Lys, Me-D-Val, and Me-L-Ala. This report represents a practical and attractive alternative for the synthesis of N-methyl-substituted cyclotripeptides. In the preliminary bioassay, synthetic xyloallenoide A showed marginal activities against KB (IC50=9.6 μM) and KBv200 cells (IC50=10.3 μM), and xyloallenoide A1 was inactive against KB and KBv200 cells.

Novel pyrimidoquinolone derivatives (VI),(XI),(XII), and (XIII), substituted at positions 2 and 3, are synthesized by using three synthetic routes and evaluated for their antiproliferative activities against a panel of six human cancer cell lines.

Simplexins M—O (IV) reduce the level of pro-inflammatory iNOS proteins in LPS-stimulated RAW264.7 macrophage cells.

Title compounds (V) are evaluated in vitro for their cytotoxicity against KB and CNE2 cell lines.

A number of enantioenriched natural-product-like or drug-like molecules with fused bi-, tri-, and polycyclic structures are constructed by synthetic transformations of some prepared Michael-adducts.

The optically active pyrimidones are prepared via an aza-Michael addition—hemiaminal formation—dehydroxylation reaction using a chiral prolinol O-Tms ether as catalyst.

The present first organocatalytic asymmetric inverse-electron-demand Diels—Alder reaction of electron-deficient dienes with crotonaldehyde gives cyclohexene derivatives with high diastereo- and enantioselectivity.

A variety of substrates, obtained by allylic—allylic alkylation of α,α-dicyanoalkenes and Morita—Baylis—Hillman carbonates, smoothly undergoes intramolecular radical cyclization.

A three-component, domino Michael—Michael—Michael—aldol process of the indole-derived substrates of the type (I) with two identical or different molecules of α,β-unsaturated aldehydes under quadruple iminium/enamine/iminium/enamine catalysis affords a variety of the enantiomerically pure hydroindane derivatives, bearing six contiguous stereocenters and a spirooxindole motif with complete diastereoselectivities [cf.

The first examples of a highly enantioselective inverse-electron-demand aza-Diels—Alder reaction of the title azabutadienes (II) employing bulky chiral secondary amine catalysts (I) are given.

Nudenoic acid, a new sesquiterpene possessing a novel tricyclic skeleton, was isolated from a Taiwanese liverwort Mylia nuda. The structure of nudenoic acid was determined by spectroscopic means and X-ray analysis.

The direct asymmetric allylic alkylation of β,γ-butenolides with MBH carbonates to access γ,γ-disubstituted butenolides containing adjacent quaternary and tertiary chiral centers has been presented in excellent stereoselectivities (86−96% ee, dr >95:5) and moderate to good yield (50−83%). Their synthetic utility has been well demonstrated by the facile construction of bicyclic lactones bearing 4−5 stereogenic centers.

Nonpeptidyl aryloxymethylphosphonates were prepared and evaluated as protein tyrosine phosphatase inhibitors. The results suggest that aryloxymethylphosphonates are effective nonhydrolyzable phosphotyrosine surrogates and provide further insight into the molecular mechanisms by which phosphate mimics inhibit phosphatase function.

The synthesis and biological activity of 2-substituted-8,9,10,11-tetrahydrobenzo[4′,5′]thieno[3′,2′:5,6] pyrido[4,3-d]pyrimidin-4(3H)-ones are described. Bioassay results indicated that these compounds have antifungal activity against Botrytis cinerea at a concentration of 50 mg/L. In addition, compounds 5m and 5n were effective to both KB cells and their parent multidrug resistant KBv200 cells with the overexpression of ABCB1. For example, compound 5m showed the best inhibition against KB and KBv200 cells with IC50 values of 17.4 and 25.4 μM, respectively.

The title compound, [Zn(C2H3O2)(C6H18N4)][B5O6(OH)4], contains mixed-ligand [Zn(CH3COO)(teta)]+ complex cations (teta is triethyl­ene­tetramine) and penta­borate [B5O6(OH)4]− anions. The [B5O6(OH)4]− anions are connected to one another through hydrogen bonds, forming a three-dimensional supra­molecular network, in which the [Zn(CH3COO)(teta)]+ cations are located.

The carbodiimides 4, obtained from aza-Wittig reactions of iminophosphorane 3 with aromatic isocyanates, reacted with amines in the presence of a catalytic amount of RO−Na+ to give the 1,2,9-trisubstituted 1,9-dihydro-6H-purin-6-ones 6 in good yields. Compound 6 exhibited cytotoxicity against various cancer cells. For example, compounds 6b showed the best inhibition activities against KB, HepG2 and OVCAR3 with IC50 9.5, 20.4 and 10.0 μM.

Sodium strontium penta­borate, Na3SrB5O10, maintains the same, previously unobserved, structure type at 200, 250 and 293 K. The fundamental building units are anionic [B5O10]5− groups distorted from mm2 point symmetry. The Sr atoms are eightfold coordinated by O atoms, forming trigonal dodeca­hedra. The Na atoms appear in three crystallographically different environments. The present single-crystal results correct a previous report in which a monoclinic cell was deduced for this compound on the basis of powder diffraction data. The structure of the title compound is discussed in the crystalochemical context of other borates with the same formula type. Although the unit cell of the present compound is similar to that determined in a previous study of the analogous Ca-containing compound, this study demonstrates that the structures of the two are different. These novel alkali–alkaline earth borates are considered as potential host materials for optical applications (fluorescence materials or phosphors).

An efficient Michael addition of indoles to unsaturated enones, such as chalcones and β-nitrostyrenes, was achieved in the presence of a catalytic amount of nitrosonium tetrafluoroborate in ethyl ether.

3,5-Disubstituted 2-isoxazolines were oxidized to corresponding isoxazoles by nitric oxide in dichloromethane. The reaction more likely occurred via a one-electron transfer process.

Vermistatin (=(3R)-4,6-dimethoxy-3-{4-oxo-6-[(1E)-prop-1-en-1-yl]-4H-pyran-3-yl}-2-benzofuran-1(3H)-one; 1) and two new vermistatin derivatives, compounds 2 and 3, were isolated from the fungal strain Guignardia sp. No. 4382 obtained from the South-China Sea. Their structures were elucidated by various methods, including circular dichroism (CD), 1D- and 2D-NMR, and HR-EI-MS. The structures of 1 and 2 were unequivocally corroborated by X-ray crystallography, and their absolute configurations were derived by CD spectroscopy based on a literature comparison. The in vitro cytotoxic and antifungal activities of 1 and 2 were tested.

Two new sesquiterpenoids named alismorientols A (1) and B (2) were isolated from the rhizomes of Alisma orientalis collected in Sichuan province, People's Republic of China. Their structures were elucidated based on spectroscopic analyses (1D and 2D NMR data including HSQC, HMBC, COSY, and ROESY) and X-ray crystallographic analysis. Anti-hepatitis B virus (HBV) bioassay revealed that compound 1 showed moderate anti-HBV activity in vitro with IC50 for HBsAg: 1.1 microM, for HBeAg: 14.7 microM.

Two new briarane-related diterpenoids, designated as briaexcavatins G (1) and H (2), were isolated from the octocoral Briareum excavatum, collected off southern Taiwan coast. The structures, includ...

Five new steroids, including the four new steroidal saponins ypsilandroside B (1), ypsilandroside A (2), isoypsilandroside A (4), and isoypsilandroside B (5), as well as the new steroidal sapogenin isoypsilandrogenin (3), were isolated from the whole plant of Ypsilandra thibetica FRANCH. Their structures were determined on the basis of spectroscopic analyses, including extensive 2D-NMR techniques. The structure and relative configuration of ypsilandroside B (=(3 beta,12 alpha,25R)-3-[(alpha-L-rhamnopyranosyl-(1 -> 2)-beta-D-apiofuranosyl)oxy]spirost-5-ene-12,27-diol; 1) was unequivocally determined by single-crystal X-ray diffraction. The antifungal and antibacterial activities of 1-5 towards various types of fungi and bacteria are reported.

A series of novel noncentrosymmetric borates, MM‘4(BO3)3 (M = Na, M‘ = Ca; M = K, M‘ = Ca, Sr), have been successfully synthesized via a standard solid-state reaction. The crystal structures have been determined by the SDPD (structure determination from powder diffraction) method. They crystallize in the noncentrosymmetric space group Ama2 with the following lattice parameters: a = 10.68004(11) A, b = 11.28574(11) A, c = 6.48521(6) A for NaCa4(BO3)3; a = 10.63455(10) A, b = 11.51705(11) A, c = 6.51942(6) A for KCa4(BO3)3; and a = 11.03843(8) A, b = 11.98974(9) A, c = 6.88446(5) A for KSr4(BO3)3. The fundamental building units are isolated BO3 anionic groups. Their second harmonic generation (SHG) coefficients were one-half (NaCa4(BO3)3), one-third (KCa4(BO3)3), and two-thirds (KSr4(BO3)3) as large as that of KH2PO4 (KDP). The infrared and UV−vis spectra of the three compounds are discussed. Moreover, a comparison of the structures of these novel compounds and three other novel cubic compounds with the sa...

A series of novel borates, MM'4(BO3)3 (M = Li, M' = Sr; M = Na, M' = Sr, Ba), have been successfully synthesized by standard solid-state reaction. The crystal structures have been determined from powder X-ray diffraction data. They crystallize in the cubic space group Iad with large lattice parameters: a = 14.95066(5) A for LiSr4(BO3)3, a = 15.14629(6) A for NaSr4(BO3)3, and a = 15.80719(8) A for NaBa4(BO3)3. The structure was built up from 64 small cubic grids, in which the M' atoms took up the corner angle and the BO3 triangles or MO6 cubic octahedra filled in the interspaces. The isolated [BO3]3- anionic groups are perpendicular to each other, distributed along three 100 directions. The anisotropic polarizations were counteracting, forming an isotropic crystal. Sr and Ba atoms were found to be completely soluble in the solid solution NaSr(4-)xBax(BO3)3 (0 < or = x < or = 4). The photoluminescence of samples doped with the ions Eu2+ and Eu3+ was studied, and effective yellow and red emission was detected, respectively. The results are consistent with the crystallographic study. The DTA and TGA curves of them show that they are chemically stable and congruent melting compounds.

Three new polyoxygenated briarane-type diterpenoids, briaexcavatolides X–Z ( 1-3 ), have been isolated from the gorgonian coral Briareum excavatum. The structures, including the relative configurations of briaranes 1-3 , were elucidated by spectroscopic methods, particularly in 1D and 2D NMR experiments. The configuration of briarane 1 was further supported by molecular mechanics calculations.

The novel structures of organometallic compounds, 1-biaryl-3-ferrocenyl-2-propene-1-one (5) and 3-biaryl-1-ferrocenyl-2-propene-1-one (9) were synthesized for nonlinear optical chromophores by Suzu...