Iron-Catalyzed Regiodivergent Hydrostannation of Alkynes: Intermediacy of Fe(IV)-H versus Fe(II)-Vinylidene.

We report an iron system, Cp*Fe(1,2-R2PC6H4X), which controls the Markovnikov and anti-Markovnikov hydrostannation of alkynes by tuning the ionic metal-heteroatom bonds (Fe-X) reactivity. The sequential addition of nBu3SnH to the iron-amido catalyst (1, X = HN-, R = Ph) affords a distannyl Fe(IV)-H species responsible for syn-addition of the Sn-H bond across the C≡C bond to produce branched α-vinylstannanes. Activation of the C(sp)-H bond of alkynes by an iron-aryloxide catalyst (2, X = O-, R = Cy) affords an iron(II) vinylidene intermediate, allowing for gem-addition of the Sn-H to the terminal-carbon producing ß-vinylstannanes. These catalytic reactions exhibit excellent regioselectivity and broad functional group compatibility and enable the large-scale synthesis of diverse vinylstannanes. Many new reactions have been established based on such a synthetic Fe-X platform to demonstrate that the initial step of the catalysis is conveniently controlled by the activation of either the tin hydride or the alkyne substrate.

Titanium-Oxide Host Clusters with Exchangeable Guests.

A novel family of water-soluble, polyoxocationic titanium-oxide host-guest clusters are reported herein. They exhibit an unprecedented hexagonal prismatic core structure for hosting univalent cationic guests like K+, Rb+, Cs+ and H3O+. Guest exchange has been studied using 133Cs NMR, showing the flexible pore of a host permits passage of a comparatively larger cation and giving an equilibrium constant of ca. 13 for displacing Rb+ by Cs+. Attractive ion-dipole interaction, depending on host-guest size complementarity, plays a dominant role for the preferential encapsulation of larger alkali-metal cationic guests.

N-Iodosuccinimide involved one-pot metal-free synthesis of 2-heteroaromatic benzothiazole compounds.

A one-pot protocol for the synthesis of structurally diverse 2-hetarylbenzothiazoles via oxidative condensation of the sp3 C-H bond with benzothiazoles has been described. This process is metal free and operationally simple. A series of 2-hetarylbenzothiazoles were prepared in moderate to good yield under mild conditions.

Hierarchical Assembly of a {Mn(II)15Mn(III)4} Brucite Disc: Step-by-Step Formation and Ferrimagnetism.

In search of functional molecular materials and the study of their formation mechanism, we report the elucidation of a hierarchical step-by-step formation from monomer (Mn) to heptamer (Mn7) to nonadecamer (Mn19) satisfying the relation 1 + Σn6n, where n is the ring number of the Brucite structure using high-resolution electrospray ionization mass spectrometry (HRESI-MS). Three intermediate clusters, Mn10, Mn12, and Mn14, were identified. Furthermore, the Mn19 disc remains intact when dissolved in acetonitrile with a well-resolved general formula of [Mn19(L)x(OH)y(N3)36-x-y](2+) (x = 18, 17, 16; y = 8, 7, 6; HL = 1-(hydroxymethyl)-3,5-dimethylpyrazole) indicating progressive exchange of N3(-) for OH(-). The high symmetry (R-3) Mn19 crystal structure consists of a well-ordered discotic motif where the peripheral organic ligands form a double calix housing the anions and solvent molecules. From the formula and valence bond sums, the charge state is mixed-valent, [Mn(II)15Mn(III)4]. Its magnetic properties and electrochemistry have been studied. It behaves as a ferrimagnet below 40 K and has a coercive field of 2.7 kOe at 1.8 K, which can be possible by either weak exchange between clusters through the anions and solvents or through dipolar interaction through space as confirmed by the lack of ordering in frozen CH3CN. The moment of nearly 50 NµB suggests Mn(II)-Mn(II) and Mn(III)-Mn(III) are ferromagnetically coupled while Mn(II)-Mn(III) is antiferromagnetic which is likely if the Mn(III) are centrally placed in the cluster. This compound displays the rare occurrence of magnetic ordering from nonconnected high-spin molecules.

General Assembly of Twisted Trigonal-Prismatic Nonanuclear Silver(I) Clusters.

A general class of C3 -symmetric Ag9 clusters, [Ag9 S(tBuC6 H4 S)6 (dpph)3 (CF3 SO3 )] (1), [Ag9 (tBuC6 H4 S)6 (dpph)3 (CF3 SO3 )2 ]⋅CF3 SO3 (2), [Ag9 (tBuC6 H4 S)6 (dpph)3 (NO3 )2 ] ⋅NO3 (3), and [Ag9 (tBuC6 H4 S)7 (dpph)3 (Mo2 O7 )0.5 ]2 ⋅2 CF3 COO (4) (dpph=1,6-bis(diphenylphosphino)hexane), with a twisted trigonal-prism geometry was isolated by the reaction of polymeric {(HNEt3 )2 [Ag10 (tBuC6 H4 S)12 ]}n , 1,6-bis(diphenylphosphino)hexane, and various silver salts under solvothermal conditions. The structures consist of discrete clusters constructed from a girdling Ag9 twisted trigonal prism with the top and bottom trigonal faces capped by diverse anions (i.e., S(2-) and CF3 SO3 (-) for compound 1, 2×CF3 SO3 (-) for compound 2, 2×NO3 (-) for compound 3, and tBuC6 H4 S(-) and Mo2 O7 (2-) for compound 4). This trigonal prism is bisected by another shrunken Ag3 trigon at its waist position. Interestingly, two inversion-related Ag9 trigonal-prismatic clusters are dimerized by the Mo2 O7 (2-) ion in compound 4. The twist is amplified by the bulkier thiolate, which also introduces high steric-hindrance for the capping ligand, that is, the longer dpph ligand. Four more silver-sulfur clusters (namely, compounds 5-8) with their nuclearity ranging from 6-10 were solely characterized by single-crystal X-ray diffraction to verify the above-described synergetic effect of mixed ligands in the construction of Ag9 twisted trigonal prisms. Surprisingly, only cluster 1 emits yellow luminescence at λ=584 nm at room temperature, which may be attributed to a charge transfer from the S 3p orbital to the Ag 5s orbital, or mixed with metal-centered (MC) d(10) →d(9) s(1) transitions. Upon cooling from 300 to 80 K, the emission intensity was enhanced along with a hypsochromic shift. The good linear relationship between the maximum emission intensity and the temperature for compound 1 in the range of 180-300 K indicates that this is a promising molecular luminescent thermometer. Furthermore, cyclic voltammetric studies indicated that the diffusion- and surface-controlled redox processes were determined for compounds 1 and 3 as well as compound 4, respectively.

Transition-metal-free synthesis of indole-fused dibenzo[b,f][1,4]oxazepines via Smiles rearrangement.

A one-pot transition-metal-free approach for the synthesis of indole-fused dibenzo[b,f][1,4]oxazepines from 2-(1H-indol-2-yl)phenol and 1,2-dihalobenzenes or 2 halonitroarenes has been developed. The proposed mechanism for this transformation features a Smiles rearrangement favoured over a direct intramolecular nucleophilic cyclization, which affords the corresponding products in different regioselectivities. This reaction also features simple reaction conditions and wide functional group tolerance.

Triarylboranes with a 2-dimesitylboryl-2'-(N,N-dimethylamino)biphenyl core unit: structure-property correlations and sensing abilities to discriminate between F(-) and CN(-) ions.

A series of triarylboranes, in which different substituents are introduced at the para position of the dimethylamino group of a 2-dimesitylboryl-2'-(N,N-dimethylamino)biphenyl core unit, have been comprehensively investigated to explore the effect of structural modification on photophysical properties. The introduction of electron-accepting substituents would facilitate the HOMO→LUMO charge transfer (CT) transition. In contrast, the intramolecular CT transition is significantly prohibited when electron-donating substituents are incorporated. Notably, the HOMO→LUMO CT transition mainly consists of the transition from the electron-donating amino group to an electron acceptor other than boryl when a strong electron acceptor such as the dicyanovinyl group is present. This dicyanovinyl-substituted compound displays sensing abilities to discriminate fluoride and cyanide ions. In solution in THF, the fluoride ions first bind to the boron center, then attack the α-carbon atom of the dicyanovinyl group, whereas the cyanide anion acts on the electron-accepting centers in the reverse sequence. As a result, the absorption and emission change in different manners upon addition of fluoride and cyanide ions.

Catalytic hydrogenation of olefins by a multifunctional molybdenum-sulfur complex.

Exploration of molybdenum complexes as homogeneous hydrogenation catalysts has garnered significant attention, but hydrogenation of unactivated olefins under mild conditions are scarce. Here, we report the synthesis of a molybdenum complex, [Cp*Mo(Ph2PC6H4S-CH = CH2)(Py)]+ (2), which exhibits intriguing reactivity toward C2H2 and H2 under ambient pressure. This vinylthioether complex showcases efficient catalytic activity in the hydrogenation of various aromatic and aliphatic alkenes, demonstrating a broad substrate scope without the need for any additives. The catalytic pathway involves an uncommon oxidative addition of H2 to the cationic Mo(II) center, resulting in a Mo(IV) dihydride intermediate. Moreover, complex 2 also shows catalytic activity toward C2H2, leading to the production of polyacetylene and the extension of the vinylthioether ligand into a pendant triene chain.

CTSD upregulation as a key driver of spinal ligament abnormalities in spinal stenosis.

Spinal stenosis (SS) is frequently caused by spinal ligament abnormalities, such as ossification and hypertrophy, which narrow the spinal canal and compress the spinal cord or nerve roots, leading to myelopathy or sciatic symptoms; however, the underlying pathological mechanism is poorly understood, hampering the development of effective nonsurgical treatments. Our study aims to investigate the role of co-expression hub genes in patients with spinal ligament ossification and hypertrophy. To achieve this, we conducted an integrated analysis by combining RNA-seq data of ossification of the posterior longitudinal ligament (OPLL) and microarray profiles of hypertrophy of the ligamentum flavum (HLF), consistently pinpointing CTSD as an upregulated hub gene in both OPLL and HLF. Subsequent RT-qPCR and IHC assessments confirmed the heightened expression of CTSD in human OPLL, ossification of the ligamentum flavum (OLF), and HLF samples. We observed an increase in CTSD expression in human PLL and LF primary cells during osteogenic differentiation, as indicated by western blotting (WB). To assess CTSD's impact on osteogenic differentiation, we manipulated its expression levels in human PLL and LF primary cells using siRNAs and lentivirus, as demonstrated by WB, ALP staining, and ARS. Our findings showed that suppressing CTSD hindered the osteogenic differentiation potential of PLL and LF cells, while overexpressing CTSD activated osteogenic differentiation. These findings identify CTSD as a potential therapeutic target for treating spinal stenosis associated with spinal ligament abnormalities.

Synthesis, structure, properties, and application of a carbazole-based diaza[7]helicene in a deep-blue-emitting OLED.

A carbazole-based diaza[7]helicene, 2,12-dihexyl-2,12-diaza[7]helicene (1), was synthesized by a photochemical synthesis and its use as a deep-blue dopant emitter in an organic light-emitting diode (OLED) was examined. Compound 1 exhibited good solubility and excellent thermal stability with a high decomposition temperature (T(d)=372.1 °C) and a high glass-transition temperature (T(g), up to 203.0 °C). Single-crystal structural analysis of the crystalline clathrate (1)(2)⋅cyclohexane along with a theoretical investigation revealed a non-planar-fused structure of compound 1, which prevented the close-packing of molecules in the solid state and kept the molecule in a good amorphous state, which allowed the optimization of the properties of the OLED. A device with a structure of ITO/NPB (50 nm)/CBP:5 % 1 (30 nm)/BCP (20 nm)/Mg:Ag (100 nm)/Ag (50 nm) showed saturated blue light with Commission Internationale de L'Eclairage (CIE) coordinates of (0.15, 0.10); the maximum luminance efficiency and brightness were 0.22 cd A(-1) (0.09 Lm W(-1)) and 2365 cd m(-2), respectively. This new class of helicenes, based on carbazole frameworks, not only opens new possibilities for utilizing helicene derivatives in deep-blue-emitting OLEDs but may also have potential applications in many other fields, such as molecular recognition and organic nonlinear optical materials.

One-pot synthesis of benzo[1,4]thiazin-3(4H)-ones and a Theoretical Study of the S-N type Smiles rearrangement mechanism.

Benzo[1,4]thiazin-3(4H)-one derivatives are conveniently prepared in one pot via a Smiles rearrangement (SR) tandem reaction. In order to understand the reaction, we present here a theoretical study on the S-N type SR mechanism.

A one-pot regioselective synthesis of benzo[d]imidazo[2,1-b]thiazoles.

Benzo[d]imidazo[2,1-b]thiazole analogues were synthesized via a one-pot metal-free procedure. A series of benzene and pyridine substrates were employed to the methodology. The desired products were generated in moderate to good yields. The effect of substituent group had also been studied.

Synthesis, X-ray crystal structure and optical properties of novel 2-aryl-3-ethoxycarbonyl-4-phenylpyrido[1,2-a]benzimidazoles.

A series of novel 2-aryl-3-ethoxycarbonyl-4-phenylpyrido[1,2-a]benzimidazole derivatives were synthesized by the tandem reaction of 2-benzoyl benzimidazole and (Z)-ethyl 4-bromo-3-arylbut-2-enoate in the presence of potassium carbonate. The compounds were characterized using IR, 1H-NMR, 13C-NMR, HRMS and the structure of 6f was further determined by X-ray crystallography. Both absorption and fluorescence spectra characteristics of the compounds were investigated in acetonitrile and dichloromethane. The results showed that the absorption maxima of the compounds varied from 220 to 284 nm, depending on the structure of 2-aryl group. The fluorescence results revealed that these compounds exhibited blue-green fluorescence (463-475 nm) in dilute solutions and showed acceptable fluorescence quantum yields (Ф(PL) = 0.13-0.73) in dichloromethane.

{2-[(Benzylphenyl-phosphanyl-κP)methyl]phenyl-κC}iodidobis(trimethyl-phos-phane)cobalt(II).

In the title compound, [Co(C(20)H(18)P)I(C(3)H(9)P)(2)], the Co(II) atom has a distorted square-pyramidal geometry, the base of which is comprised of two trans PMe(3) groups, an I atom, and a C atom of the benzyl group. This benzyl group is tethered to the P atom at the apex of the pyramid, thereby forming a five-membered chelated Co-C-C-C-P ring.

Ethyl 1-benzyl-3-(4-bromo-phen-yl)-1H-pyrazole-5-carboxyl-ate.

In the title compound, C(19)H(17)BrN(2)O(2), the pyrazole ring makes dihedral angles of 88.00 (16) and 5.78 (13)° with the phenyl and bromo-phenyl rings, respectively. In the crystal, mol-ecules are linked by weak inter-molecular C-H⋯O hydrogen bonds.

Dehydrogenation of iron amido-borane and resaturation of the imino-borane complex.

We report on the first isolation and structural characterization of an iron phosphinoimino-borane complex Cp*Fe(η2-H2B[double bond, length as m-dash]NC6H4PPh2) by dehydrogenation of iron amido-borane precursor Cp*Fe(η1-H3B-NHC6H4PPh2). Significantly, regeneration of the amido-borane complex has been realized by protonation of the iron(ii) imino-borane to the amino-borane intermediate [Cp*Fe(η2-H2B-NHC6H4PPh2)]+ followed by hydride transfer. These new iron species are efficient catalysts for 1,2-selective transfer hydrogenation of quinolines with ammonia borane.

(3-Phenyl-isoxazol-5-yl)methanol.

In the title compound, C(10)H(9)NO(2), the isoxazole and phenyl rings form a dihedral angle of 25.82 (3)°. In the crystal, inter-molecular O-H⋯O hydrogen bonds link the mol-ecules into ribbons propagating along [001]. The crystal packing is further stabilized by weak C-H⋯O and C-H⋯N inter-actions.

Ethyl 3-{5-[(diethyl-amino)meth-yl]isoxazol-3-yl}-2-phenyl-pyrazolo[1,5-a]pyridine-5-carboxyl-ate.

In the title compound, C(24)H(26)N(4)O(3), the pyrazolo[1,5-a]pyridine ring system makes dihedral angles of 38.130 (3) and 30.120 (3)°, respectively, with the isoxazole and phenyl rings. In the crystal, two mol-ecules are linked by a pair of C-H⋯N hydrogen bonds, forming a centrosymmetric dimer. A weak intra-molecular C-H⋯O inter-action is also present.

[Determination of brix and POL in sugar cane juice by using near infrared spectroscopy coupled with BP-ANN].

The models of quantitative analysis of brix and pol in sugar cane juice were established by using near infrared spectroscopy (NIR) coupled with the back propagation-artificial neural network method (BP-ANN). The spectra of cane juice samples were obtained by the way of 2 mm optical length transmission and using the NIR spectrometer of 1,000-1,800 nm wavelength. Firstly, the data of original spectra were pretreated by Savitzky-Golay derivative and mean-centering. Secondly, the wavelength range of model was optimized by using correlation coefficient method coupled with the characteristic absorbance of the spectrum. Finally, the principal components, obtained by PLS dimension-reducing, were inputed into BP-ANN. The calibration models were established by calibration set and validated by prediction set. The results showed that the related coefficients (R2) of prediction for brix and pol were 0.982 and 0.979, respectively; and the standard errors of prediction (SEP) for brix and pol were 0.159 and 0.137, respectively. BP-ANN was more accurate in the prediction of brix and pol compared with the partial least square method (PLS). The method can be applied to fast and accurate determination of brix and pol in sugar cane juice.

Ethyl 6-methyl-2-p-tolyl-pyrazolo[1,5-a]pyridine-5-carboxyl-ate.

In the title mol-ecule, C(18)H(18)N(2)O(2), the bicyclic ring system and the benzene ring form a dihedral angle of 13.45 (3)°. In the crystal structure, weak inter-molecular C-H⋯O hydrogen bonds link mol-ecules into chains propagated along [201].