Design of multivalent galactosyl carborane as a targeting specific agent for potential application to boron neutron capture therapy

A multivalent galactosyl carborane derivative 10 (dendritic glyco-borane, DGB) was synthesized and demonstrated as a potential cell-targeting agent in BNCT with HepG2 cells. DGB 10 improved the delivery of boron to HepG2 cells and neutron irradiation data show DGB 10 with ten-fold improvement at killing the HepG2 cells over BSH.     

A new 8-connected self-penetrating metal-organic framework based on dinuclear cadmium clusters as secondary building units

A new metal-organic framework（MOF） based on metal clusters as secondary building units（SBU）,has been synthesized and structurally characterized.The reported MOF presents an interesting 8-connected self-penetrating coordination network based on dinuclear cadmium cluster with a 4²⁴·5·6³ topology. Moreover,the thermal stability and luminescence property of this compound have been investigated.     

Synthesis and molecular structure of a manganese tricarbonyl complex based on 5,6-nido-C2B8H12 carborane

Russian Chemical Bulletin - The anionic manganese tricarbonyl complex [1,1,1-(CO)3-isonido-1,2,4-MnC2B8H10]–was synthesized in the form of PPN and tmdaH salts (PPN is...     

Conjugates of polyhedral boron compounds with carbohydrates. 4. hydrolytic stability of carborane–lactose conjugates depends on the structure of a spacer between the carborane cage and sugar moiety

A novel 1,2‐dicarba‐closo‐dodecaborane–lactose conjugate ( 4a ) with an N‐glycosidic linkage was synthesized. This conjugate was found to be much more stable against hydrolytic deboronation (closo to nido tranformation of the carborane cage) under neutral conditions than a related carborane–lactose conjugate ( 1a ) with an O‐glycosidic linkage. This result demonstrates that the hydrolytic stability of carborane–carbohydrate conjugates in neutral aqueous solutions may depend dramatically on the chemical nature of the spacer that links the carbohydrate moiety with the boron cage, the rate of hydrolysis varying by orders of magnitude. We relate a significant decrease in the deboronation rate to the formation of more strongly bound supramolecular aggregates, in which the boron cage is less accessible to nucleophilic attack by solvent molecules, in the solution of the carborane–N‐lactoside conjugate 4a . Copyright © 2006 John Wiley & Sons, Ltd.     

Synthesis, structure, and magnetic properties of a new eight-connected metal-organic framework (MOF) based on Co4 clusters

A hydrothermal reaction of cobalt nitrate, 4,4'-oxybis(benzoic acid) (OBA), 1,2,4-triazole, and NaOH gave rise to a deep purple colored compound [Co(4)(triazolate)(2)(OBA)(3)], I, possessing Co(4) clusters. The Co(4) clusters are connected together through the tirazolate moieties forming a two-dimensional layer that closely resembles the TiS(2) layer. The layers are pillared by the OBA units forming the three-dimensional structure. To the best of our knowledge, this is the first observation of a pillared TiS(2) layer in a metal-organic framework compound. Magnetic studies in the temperature range 1.8-300 K indicate strong antiferromagetic interactions for Co(4) clusters. The structure as well as the magnetic behavior of the present compound has been compared with the previously reported related compound [Co(2)(μ(3)-OH)(μ(2)-H(2)O)(pyrazine)(OBA)(OBAH)] prepared using pyrazine as the linker between the Co(4) clusters.     

一系列新型硼氮化合物的理论研究

借助密度泛函理论,在B3LYP/6-311 G**和BP86/6-311 G**水平上,对一系列包含BNN单元的硼氮化合物BNN,H3BNN,NNBH2-BH2NN,(BNN)2H2,NN-BBNN,(BNN)3 ,(BNN)42 ,(BNN)5-,(BNN)6,(BNN)7 和(BNN)82 进行了理论计算研究.结果表明:在这些硼氮化合物中,尤其是BNN,B原子和N2配体之间存在着σ-π反馈作用.这种作用增强了B-N键,而活化了N-N键.结果还显示,(BNN)3 ,(BNN)42 ,(BNN)5-,(BNN)6,(BNN)7 和(BNN)82 都是具有平面单环结构并且满足4n 2规则的芳香性体系.     

A quantum chemistry study: a new kind of boron nitrides

At the B3LYP/6-311+G** and the BP86/6-311+G** levels of theory, BNN, H(3)BNN, NNBH(2)-BH(2)NN, (BNN)(2)H(2), NNBBNN, (BNN)(3) (+), (BNN)(4), (BNN)(4) (2+), (BNN)(4) (2-), B(4)(NN)(2), (BNN)(5) (-), (BNN)(6), (BNN)(7) (+), and (BNN)(8) (2+) are investigated. Neutral (BNN)(4) is aromatic with its triplet state but antiaromatic with its singlet state. (BNN)(4) dication favors D(2d) structure, while (BNN)(4) dianion favors a planar D(4h) structure. (BNN)(3) (+), (BNN)(4) (2-), (BNN)(5) (-), (BNN)(6), (BNN)(7) (+), (BNN)(7) (3-), (BNN)(8) (2+), and (BNN)(8) (2-) are all aromatic with planar monocyclic conformation, following the 4n + 2 rule. Moreover, according to the CASSCF and MRCI calculations, the planar B(4)(NN)(2) of D(2h) symmetry prefers to be a sigma-pi diradical in spite of open-shell singlet or triplet and is also aromatic. Akin to the sigma-pi back interaction in compounds containing transition metal, there exists the sigma-pi back interaction between boron and N(2) ligand among some species reported herein, which strengthens B(-)N bond but activates N-N bond, especially in (4)Sigma(-) BNN. The T-shaped structure lies lowest in energy among seven isomers of the (BNN)(2)H(2) dimer, and the parallel-displaced structure is favored between two isomers of the (BNN)(6) dimer.     

A Helquat-like Compound as a Potent Inhibitor of Flaviviral and Coronaviral Polymerases

Positive-sense single-stranded RNA (+RNA) viruses have proven to be important pathogens that are able to threaten and deeply damage modern societies, as illustrated by the ongoing COVID-19 pandemic. Therefore, compounds active against most or many +RNA viruses are urgently needed. Here, we present PR673, a helquat-like compound that is able to inhibit the replication of SARS-CoV-2 and tick-borne encephalitis virus in cell culture. Using in vitro polymerase assays, we demonstrate that PR673 inhibits RNA synthesis by viral RNA-dependent RNA polymerases (RdRps). Our results illustrate that the development of broad-spectrum non-nucleoside inhibitors of RdRps is feasible.     

Investigation of the typical triangular structure B3 in boron chemistry: insight into bare all-boron clusters used as ligands or building blocks

Even though boron clusters are quite significant, bare boron clusters as ligands in chemical compounds are still unknown. Triangular B(3) is a key constituent of all-boron clusters and widely applied in the boron compounds. As a basic step toward understanding the assembly and stabilization of bare all-boron clusters and the possibility of their fusion during the cluster-assembly process, we made the first attempt to assemble the smallest bare all-boron unit B(3)-. Both the "homo-decked sandwich" and "hetero-decked sandwich" schemes were applied to the assembly of B(3)- at the B3LYP/6-311++G(d, p) level. For all the considered alkali- and alkaline earth metals, B(3)- can only be assembled in "hetero-decked sandwich" scheme (e.g., CpMB(3)(q-)) so as to avoid cluster fusion, whereas it cannot be assembled in the traditional "homo-decked sandwich" scheme (B(3)MB(3)(q-)) because of thermodynamic and kinetic instability. Various assembled species in extended frameworks are designed. In particular, the dimerization of the hetero-decked sandwich-like CpMB(3)(q-) could lead to a new type of antiaromatic triple-decker sandwich-like complexes CpMB(6)Cp(2q-) that contain the all-boron antiaromatic unit B(6)(2-). Our work supports the experimental identification of the B(6)(2-) anion (with M+ counterions) in a photoelectron spectroscopy study. Additionally, the electronic and structural properties of B(3)- are well conserved during cluster-assembly, characteristic of a "superatom" feature. Our results are expected to be helpful for understanding the assembly and stabilization of bare all-boron cluster chemistry. Also, our work should give insight toward designing and understanding bare boron clusters as potential new ligands for coordination chemistry and as new building blocks for materials science. Interestingly, our results should provide hints to embellish, functionalize, isolate, and protect bare all-boron clusters.     

Synthesis and characterization of poly(aminoborane) as a new boron nitride precursor

During the solution reaction of NaBH₄/(NH₄)₂SO₄ in tetraglyme to form borazine, polymeric aminoborane (NH₂BH₂)_x has been isolated as a white powder. The powder was characterized by thermal gravimetric analysis/differential scanning calorimetry, infrared and mass spectroscopies, and powder X‐ray diffraction. Solid‐state ¹⁵N and ¹¹B nuclear magnetic resonance firmly proved that the chain‐like poly(aminoborane) evolved a partially condensed B₃N₃ ring structure by dehydrogenative condensation between chains at 200 °C. Pyrolysis of the polymer in a nitrogen stream up to 1400 °C led to a 75% yield of hexagonal boron nitride with an interlayer spacing of 3.37 Å. Copyright © 1999 John Wiley & Sons, Ltd.     

A one‐dimensional chain structure based on unusual tetranuclear manganese(II) clusters

The title coordination polymer, poly[bis(μ₄‐biphenyl‐2,2′‐dicarboxylato)(dipyrido[3,2‐a:2′,3′‐c]phenazine)manganese(II)], [Mn₂(C₁₄H₈O₄)₂(C₁₈H₁₀N₄)]_n, was obtained through the reaction of MnCl₂·4H₂O, biphenyl‐2,2′‐dicarboxylic acid (H₂dpdc) and dipyrido[3,2‐a:2′,3′‐c]phenazine (L) under hydrothermal conditions. The asymmetric unit contains two crystallographically unique Mn^II ions, one unique L ligand and two unique dpdc ligands. One Mn ion is six‐coordinated by four O atoms from three different dpdc ligands and two N atoms from one L ligand, adopting a distorted octahedral coordination geometry. The distortions from ideal octahedral geometry are largely due to the presence of chelating ligands and the resulting acute N—Mn—N and O—Mn—O angles. The second Mn ion is coordinated in a distorted trigonal bipyramidal fashion by five O atoms from four distinct dpdc ligands. Four Mn^II ions are bridged by the carboxylate groups of the dpdc ligands to form an unusual tetranuclear Mn^II cluster. Clusters are further connected by the aromatic backbone of the dicarboxylate ligands, forming a one‐dimensional chain structure along the b axis. The title compound is the first example of a chain structure based on a tetranuclear Mn^II cluster.     

A new photoimaging system based on a trisdiazonium salt as a photocrosslinker for sulfonated polyelectrolytes

A photocrosslinker based on a trisdiazonium salt has been synthesized from 4,4′,4″-triaminotriphenylamine. Polyelectrolyte complexes can be obtained by mixing the trisdiazonium crosslinker with poly(styrenesulfonate) (PSS). The polyelectrolyte complex precipitates when PSS is added in an ionic ratio of around 1:1 to a trisdiazonium salt solution. However, the addition of an excess of PSS to the mixture leads to redissolution of the precipitate. A mixture of PSS and the photocrosslinker (27 wt.%) can be processed from solution to give thin films by spin coating. When the films are irradiated with UV light, a change in the solubility of the material is observed, which is due to the decomposition of diazonium groups and the transformation of the ionic bond into a covalent one, which in turn transforms the polyelectrolyte complex into a covalent network. The process has been characterized by UV and IR spectroscopy. Photoimaging experiments have been performed on this material and polymeric relief structures have been obtained through a photolithographic process.     

Synthesis of a new boron carbonitride with a B4C-like structure from the thermolysis of N-alkylated borazines

Thermolysis of N-trialkyl borazines at 500 degrees C produces homogeneous, amorphous boron carbonitride phases, whose compositions are dependent upon the borazine substituent, and whose structures are similar to that of icosahedral boron carbide, B4C.     

A new method for the synthesis of bishydroperoxides based on a reaction of ketals with hydrogen peroxide catalyzed by boron trifluoride complexes

A reaction of cycloalkanone, alkanone and alkyl aryl ketone ketals with H₂O₂ catalyzed by boron trifluoride etherate and boron trifluoride-methanol complexes was studied. A new versatile method for the synthesis of bishydroperoxides and their derivatives, viz. 1,1′-dihydroperoxyperoxides and 1,2,4,5-tetraoxacyclohexanes, was developed based on this reaction.