Synthesis and Characterization of Tri(organotin)Substituted Heteropolytungstates

ＳｙｎｔｈｅｓｉｓａｎｄＣｈａｒａｃｔｅｒｉｚａｔｉｏｎｏｆＴｒｉ（ｏｒｇａｎｏｔｉｎ）ＳｕｂｓｔｉｔｕｔｅｄＨｅｔｅｒｏｐｏｌｙｔｕｎｇｓｔａｔｅｓＹＡＮＧＱｉ－ｈｕａ,ＤＡＩＨｕｉ－ｃｏｎｇ,ＬＩＵＪｉｎｇ－ｆｕ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍ...     

Investigation of Copper Halide:Hydrothermal Syntheses and Characterization of CuBr2(C12H8N2) and Cu3Br3(C12H8N2)2

The reaction of CuBr₂ with 1,10‐phen‐H₂O (1,10‐phen = 1,10‐phenanthroline) gave two compounds: CuBr₂(C₁₂H₈N₂) and Cu₃Br₃(C₁₂H₈N₂)₂. Their structures have been characterized by single‐crystal X‐ray diffraction analysis, elemental analyses, thermogravimetric analyses (TGA) and measurement of variable temperature magnetic susceptibility. Crystal data for CuBr₂(C₁₂‐H₈N₂): monoclinic, space group P2₁/n, a = 0.9977(3) nm, b = 0.65138(14) nm, c = 1.8207(4) nm, β = 91.624(18)°, V = 1.1828(5) nm³, Z = 2. Crystal data for Cu₃Br₃(C₁₂H₈N₂)₂: monoclinic, space group C2/c, a = 1.00167(11) nm, b = 1.4523(4) nm, c = 1.6295(3) nm, β = 94.386(14)°, V = 2.3635(8) nm³, Z = 3.     

Atomistic Structures,Stabilities, Electronic Properties,and Chemical Bonding of Boron–Aluminum Mixed Clusters B3Al n 0/−/+ (n = 2–6)

Journal of Cluster Science - Neutral, anionic, and cationic B3Al n 0/?/+ (n?=?2–6) clusters were systematically explored using density functional theory and coupled cluster...     

A Chemical Biology Approach to Understanding Molecular Recognition of Lipid II by Nisin(1–12): Synthesis and NMR Ensemble Analysis of Nisin(1–12) and Analogues

Natural products that target lipid II, such as the lantibiotic nisin, are strategically important in the development of new antibacterial agents to combat the rise of antimicrobial resistance. Understanding the structural factors that govern the highly selective molecular recognition of lipid II by the N-terminal region of nisin, nisin(1–12), is a crucial step in exploiting the potential of such compounds. In order to elucidate the relationships between amino acid sequence and conformation of this bicyclic peptide fragment, we have used solid-phase peptide synthesis to prepare two novel analogues of nisin(1–12) in which the dehydro residues have been replaced. We have carried out an NMR ensemble analysis of one of these analogues and of the wild-type nisin(1–12) peptide in order to compare the conformations of these two bicyclic peptides. Our analysis has shown the effects of residue mutation on ring conformation. We have also demonstrated that the individual rings of nisin(1–12) are pre-organised to an extent for binding to the pyrophosphate group of lipid II, with a high degree of flexibility exhibited in the central amide bond joining the two rings.     

C–O,C–S,C–N,and C–C Bond Formation at the Periphery of the Macrocycle during Chemical Modification of Phytochlorins: Key Methods and Synthetic Applications

Russian Journal of General Chemistry - The main methods of C-O, C-S, C-N, and C-C bond formation at the periphery of the macocrocycle during chemical modification of phytochlorins in the synthesis...     

Metastable Aluminum(I) Compounds: Experimental and Quantum Chemical Investigations on Aluminum(I) Phosphanides—An Alternative Channel to the Disproportionation Reaction?

The well known thermodynamic instability of Al and Ga monohalides is caused by the favored disproportionation process to the bulk metal and the trihalides. During this highly complex process, a number of metalloid clusters that are intermediates on the way to the metal have been trapped. Therefore, all observations in the field of metalloid Al/Ga clusters have been traced to this favored disproportionation process. The failure to form phosphanide‐substituted Al clusters, in contrast to the generation of similar Ga clusters and analogous Al amide clusters, was the starting point of this contribution. For aluminum(I) phosphanides, there exists a different decomposition route in which the salt‐like bulk material AlP and not Al metal is the final product. The synthesis of two molecular “AlP” intermediate species, together with supporting DFT calculations, provide plausible arguments for this decomposition route, which is thermodynamically favored for many AlR/GaR species and which, surprisingly, has not been discussed before.     

Synthesis and Characterization of New α,ω-Bis(Maleimide-Ester) Substituted Siloxane Oligomers

Abstract

Organofunctional siloxane oligomers containing maleimide were synthesized by condensation reaction of α. ω-hydroxypropylsiloxane oligomers with n-[4-(chlorocarbonyl)phenyl]maleimide. A model compound [bis(maleimide-ester)disiloxane] was obtained to facilitate the characerization of the oligomers. Then, the heterogeneous catalyzed ring-opening cationic polymerization technique was applied to obtain an oligomer starting from the model compound and octamethylcyclotetrasiloxane.

The structures of the resulting oligomers were confirmed by elemental analysis, IR and ¹H-NMR spectroscopy. They were characterized by determining softening points, solubility and studying their thermal behavior by thermogravimetric (TGA and differential scanning calorimetry (DSC) measurements.     

Gold-catalyzed cascade C–C and C–N bond formation: synthesis of polysubstituted indolequinones and pyrroles

The combination of Ph₃PAuCl and AgOTf was proven to be an efficient catalyst for the cascade C–C and C–N bond formation reactions from enamines and bromoquinones or nitroolefins. This protocol affords a straightforward method for the synthesis of polysubstituted indolequinones and pyrroles in good yields.     

[(C C)Au(N N)]+ Complexes as a New Family of Anticancer Candidates: Synthesis,Characterization and Exploration of the Antiproliferative Properties

A library of eleven cationic gold(III) complexes of the general formula [(C C)Au(N N)]⁺ when C C is either biphenyl or 4,4’-ditertbutyldiphenyl and N N is a bipyridine, phenanthroline or dipyridylamine derivative have been synthesized and characterized. Contrasting effects on the viability of the triple negative breast cancer cells MDA-MB-231 was observed from a preliminary screening. The antiproliferative activity of the seven most active complexes were further assayed on a larger panel of human cancer cells as well as on non-cancerous cells for comparison. Two complexes stood out for being either highly active or highly selective. Eventually, reactivity studies with biologically meaningful amino acids, glutathione, higher order DNA structures and thioredoxin reductase (TrxR) revealed a markedly different behavior from that of the well-known coordinatively isomeric [(C N C)Au(NHC)]⁺ structure. This makes the [(C C)Au(N N)]⁺ complexes a new class of organogold compounds with an original mode of action.     

Synthesis,Characterization, and Electron-Transfer Properties of Ferrocene–BODIPY–Fullerene Near-Infrared-Absorbing Triads: Are Catecholopyrrolidine-Linked Fullerenes a Good Architecture to Facilitate Electron-Transfer?

A series of covalent ferrocene–BODIPY–fullerene triads with the ferrocene groups conjugated to the BODIPY π-system and the fullerene acceptor linked at the boron hub by a common catecholpyrrolidine bridge were prepared and characterized by 1D and 2D NMR, UV/Vis, steady-state fluorescence spectroscopy, high-resolution mass spectrometry, and, for one of the derivatives, X-ray crystallography. Redox processes of the new compounds were investigated by electrochemical (CV and DPV) methods and spectroelectrochemistry. DFT calculations indicate that the HOMO in all triads was delocalized between ferrocene and BODIPY π-system, the LUMO was always fullerene-centered, and the catechol-centered occupied orbital was close in energy to the HOMO. TDDFT calculations were indicative of the low-energy, low-intensity charge-transfer bands originated from the ferrocene–BODIPY core to fullerene excitation, which explained the similarity of the UV/Vis spectra of the ferrocene–BODIPY dyads and ferrocene–BODIPY–fullerene triads. Photophysical properties of the new triads as well as reference BODIPY–fullerene and ferrocene–BODIPY dyads were investigated by pump-probe spectroscopy in the UV/Vis and NIR spectral regions following selective excitation of the BODIPY-based antenna. Initial charge transfer from the ferrocene to the BODIPY core was shown to outcompete sub-100 fs deactivation of the excited state mediated by the catechol bridge. However, no subsequent electron transfer to the fullerene acceptor was observed. The initial charge separated state relaxes by recombination with a time constant of 150–380 ps.     

Synthesis and Characterization of Poly(hydrogen halide) Halogenates (–I)

Herein, we report the synthesis and characterization of a variety of novel poly(hydrogen halide) halogenates (−I). The bifluoride ion, which is known to have the highest hydrogen bond energy of ≈160 kJ mol⁻¹, is the most famous among many examples of [X(HX)_n]⁻ anions (X=F, Cl) known in the literature. In contrast, little is known about poly(hydrogen halide) halogenates containing two different halogens, ([X(HY)_n]⁻). In this work we present the synthesis of anions of the type [X(HY)_n]⁻ (X=Br, I, ClO₄; Y=Cl, Br, CN) stabilized by the [PPh₄]⁺ and [PPN]⁺ cation. The obtained compounds have been characterized by single-crystal X-ray diffraction, Raman spectroscopy and quantum-chemical calculations. In addition, the behavior of halide ions in hydrogen fluoride was investigated by using experimental and quantum-chemical methods in order to gain knowledge on the acidity of hydrogen halides in HF.     

Efficient Synthesis of 2‐(N‐Substituted)‐2‐imidazolines and 2‐(N‐Substituted)‐1,4,5,6‐tetrahydropyrimidines

A general method for the preparation of 2‐(N‐Substituted)‐2‐imidazolines and 2‐(N‐Substituted)‐1,4,5,6‐tetrahydropyrimidines is described. These heterocycles can be synthesized from their respective anilines with 2‐chloro‐2‐imidazoline or 2‐chloro‐1,4,5,6‐tetrahydropyrimidine, generated in situ from imidazolidin‐2‐one and tetrahydropyrimidin‐2(1H)‐one activated by dimethyl chlorophosphate, in good to excellent yields.     

Synthesis of the Southern Tripeptide (C1–N12) of Sanglifehrins Using Asymmetric Organocatalysis

The tripeptide southern region of the novel cyclophilin binding natural product macrolides, namely sanglifehrins, is synthesized involving asymmetric organocatalysis as chirality-inducing step. List's asymmetric α-amination was used in the synthesis of the m-hydroxyphenylalanine part, whereas α-hydrazination was used for the piperazic ester part.     

Electronic properties of B12N12 fullerene–like nanoclusters functionalized with Schiff bases: a DFT study

Structural Chemistry - In the present study, electronic properties of B12N12 nanocage functionalized with Schiff bases are studied by means of density functional theory (DFT) calculations at...     

New Quasi-One-Dimensional Crystals of Metallocarbohedrenes (Sc,Ti,V)8C12 in (12,0) Boron–Nitrogen Nanotubes: Quantum-Chemical Simulation

A quantum-chemical model was made of new quasi-one-dimensional crystals, consisting of regular chains of metallocarbohedrenes Sc₈C₁₂, Ti₈C₁₂, and V₈C₁₂ (isomers with T _h symmetry) inside a single-wall (12,0) boron–nitrogen nanotube. Their electronic characteristics, the nature of the interatomic bonds, and the relative stability in relation to the electronic concentration in the (Sc₈C₁₂@(12,0)BN-NT Ti₈C₁₂@(12,0)BN-NT V₈C₁₂@(12,0)BN-NT) systems and the mutual arrangement of the metallocarbohedrenes and the nanotube are discussed.     

Cu(I) metal organic framework catalyzed C–C and C–N coupling reactions

DABCO (1,4-diazabicyclo[2.2.2]octane) based Cu(I) metal organic framework (here after represented as Cu(I)-MOF) catalyzed Sonogashira cross-coupling reaction of iodobenzene and phenylacetylene was conducted smoothly to afford diphenylacetylene in excellent yield under N₂ atmosphere. For comparative study, piperidine based Cu(I) clusters were also investigated. Among these catalysts, Cu(I)-MOF exhibited higher activity with good selectivity for the C–C cross-coupled product. Cu(I) catalysts investigated in this study exhibited similar activity in the C–C homo-coupling reaction of phenylacetylene in O₂ atmosphere. Application of these catalysts was extended in the C–N coupling reactions between phenylboronic acid and aromatic/aliphatic/heterocyclic amines. Cu(I)-MOF can be readily recovered from the reaction mixture and reused for several cycles without loss in the catalytic activity.     

Introduction to the Chinese Society of Chemical Science and Technology in the UK(CSCST-UK)and Chinese Section of Society of Chemical Industry(SCI-CS)

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