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Atomic layer deposition (ALD) is widely recognized as a unique chemical vapor deposition technique for the fabrication of thin films with high conformality and precise thickness control down to the Ångstrom level, thereby allowing surface and interface nanoengineering. However, several challenges such as the availability of chemical precursors for ALD and the use of vacuum conditions have hampered its widespread adoption and scalability for mass production. In recent years, the liquid phase homolog of ALD, liquid atomic layer deposition (LALD), has emerged as a much simpler and versatile strategy to overcome some of the current constraints of ALD. This perspective describes the different strategies that have been explored to achieve conformality and sub-nanometer thickness control with LALD, as well as the current challenges it faces to become a part of the thin-film community toolbox, in particular its automation and compatibility with different types of substrates. In this regard, the important role of LALD as complementary technology to ALD is emphasized by comparing the different pathways to deposit the same material and the precursors used to do so. [ABSTRACT FROM AUTHOR]

Two families of internally functionalized multifaceted organochalcogen compounds based on flexible and rigid backbones, viz., N,N-dimethylaminoalkyl and pyridyl/pryrimidyl groups, have been designed and developed in the author's group. These compounds exhibit remarkable ligand chemistry and often show unprecedented reactivity leading to the formation of several serendipitous products. The presence of both soft (chalcogen) and hard (nitrogen) donor atoms makes them hemilabile ligands which facilitates the design of palladium based homogeneous catalysts for C–C coupling and other related reactions. Pyridyl and pyrimidyl based chalcogenolato complexes of Group 10–15 metals have been successfully employed as molecular precursors for the preparation of metal chalcogenide nano-crystals and for deposition of thin films. By making a suitable choice of chalcogenolate ligands and reaction conditions, a single phasic material can be isolated conveniently. 2-Pyridyl and 2-pyrimidyl ring systems, being important constituents of several biological molecules, several selenium based 2-pyridyl and 2-pyrimidyl compounds show promising GPx mimicking activity. The substituents at the C-3 position play a key role in governing the molecular structure as well as GPx activity. [ABSTRACT FROM AUTHOR]

Control of the redox potential of lithium terephthalate Li2TP anode material is demonstrated by functionalizing its terephthalate backbone with an electron-donating amino group; this lowers – as intended – the redox potential of Li2TP by 0.14 V. The two Li-organic electrode materials, Li2TP and Li2TP-NH2, are fabricated as crystalline thin films from gaseous precursors using the atomic/molecular layer deposition (ALD/MLD) technique. The amino-functionalized material possesses a previously unknown crystal structure, addressed here by applying the USPEX evolutionary algorithm for the structure prediction and then LeBail fitting of the experimental XRD pattern based on the predicted structure model. The ALD/MLD fabrication yields in situ lithiated active electrode materials without any conductive additivies or binders and thus allows a straightforward evaluation of their intrinsic electrochemical properties. Comparison between Li2TP and its amino-functionalized derivative reveals inferior capacity retention and rate capability characteristics for the latter, which somewhat counterveils the pros-and-cons balance between the two Li-organic electrode materials. From galvanostatic cycling experiments and post-mortem XRD and SEM analysis, the issue with Li2TP-NH2 is revealed to be in the morphology changes occurring during the discharge/charge cycling. [ABSTRACT FROM AUTHOR]

In this work, a hexanuclear lithium compound, [Li6(MesalO)6] (1), supported by a chelating ligand, namely methyl salicylato (MesalOH), was used as a precursor for preparation of the monomeric lithium aryloxides [Li(MesalO)(MesalOH)] (2) and [Li(MesalO)(MeOH)2] (3) via reactions with MesalOH or MeOH. These aryloxides were characterized by single-crystal X-ray diffraction, and spectroscopic and other analytical methods. The diffusion-ordered 1H NMR measurements revealed the retention of solid-state structures of 1 and 2 in THF-d8 solution. Experimental data obtained for 3 showed its decomposition into compound 1 and free MeOH. Compound 1 generated from 3 was also used as a catalyst for the alcoholysis of L -lactide (L -LA) and glycolide (GA) for the preparation of α-hydroxy acid esters. We established that during methanolysis in the presence of 1, L -LA was selectively transformed into methyl (S,S)-O-lactyllactate (MeL2), and GA was converted to methyl glycolate (MeG1) and oligoglycolate esters MeGn (n = 2, 3, and 4). [ABSTRACT FROM AUTHOR]

Knowledge about the appropriate indicators to point out the best components in a catalytic process is a basic prerequisite for obtaining insights into optimized reactions as, for example, in the chemical vapour deposition method, which enables the growth of carbon nanotubes. In this work, we report a density functional theory study of 13-atom transition-metal nanoclusters interacting with (5,0) zigzag and (3,3) armchair carbon nanotube fragments, considering all transition-metal species from the periodic table as possible candidates for the chemical vapour deposition method. The icosahedral configuration was found to be a good model to simulate the seed of nucleation in the case of the short carbon nanotube fragments that are initially formed during the growth process. From full geometric optimizations, without any constraints, we found that the energetic and structural nanocluster properties change as a function of the occupation of the bonding and anti-bonding d-states. The center of gravity of the occupied d-states for nanoclusters is found to be a good indicator to reveal the best candidates for the interaction with the carbon nanotubes, namely, Sc–Cu, Y–Nb, Pd, Lu, Hf, and Pt. The interaction between all transition-metal nanoclusters with both armchair and zigzag segments is favorable in terms of the adhesion energy, where the adhesion is larger for systems with smaller occupation of the d-states. The bond strength is more pronounced for systems with zigzag fragments than those with armchair fragments, which is confirmed by the smaller average bond length between the metal atoms of the nanocluster and the C atoms of the zigzag segment. Our prediction about the best 13-atom transition-metal candidates is reinforced by the linear relationship between the adhesion energy and the center of gravity of the occupied d-states. Thus, the adhesion energy presents increased intensity for the interaction between carbon nanotube fragments and nanoclusters in relation to the smaller occupation of the d-states. Consequently, our model is able to provide a good descriptor for indicating the best 13-atom transition-metal candidates in the chemical vapour deposition process. [ABSTRACT FROM AUTHOR]

A cyclic tri-nuclear α-diimine nickel(0) complex [{Ni(μ-LMe-2,4)}3] (2) was synthesized from a “pre-organized”, trimerized trigonal LNiBr2-type precursor [Ni3(μ2-Br)3(μ3-Br)2(LMe-2,4)3]·Br (1; LMe-2,4 = [(2,4-Me2C6H3)NC(Me)]2). In complex 2, the α-diimine ligands not only exhibit the normal N,N′-chelating mode, but they also act as bridges between the Ni atoms through an unusual π-coordination of a C=N bond to Ni. Complex 2 is able to catalyze the cyclotrimerization of alkynes to form substituted benzenes in good yield and regio-selectivity for the 1,3,5-isomers, which is found to vary with the nature of the alkyne employed. This complex represents a convenient self-supported nickel(0) catalyst with no need for additional ligands and reducing agent. [ABSTRACT FROM AUTHOR]

This work focuses on the application of dicobalt octacarbonyl (Co2(CO)8) as a metal precursor in the chemistry of formally low-valent cobalt with redox-active bis(imino)pyridine [NNN] ligands. The reactions of both mononucleating mesityl-substituted bis(aldimino)pyridine (L1) and dinucleating macrocyclic xanthene-bridged di(bis(aldimino)pyridine) (L2) with Co2(CO)8 were investigated. Independent of the metal-to-ligand ratio (1 : 1 or 1 : 2 ligand to Co2(CO)8), the reaction of the dinucleating ligand L2 with Co2(CO)8 produces a tetranuclear complex [Co4(L2)(CO)10] featuring two discrete [Co2[NNN](CO)5] units. In contrast, a related mononucleating bis(aldimino)pyridine ligand, L1, produces different species at different ligand to Co2(CO)8 ratios, including dinuclear [Co2(CO)5(L1)] and zwitterionic [Co(L1)2][Co(CO)4]. Interestingly, [Co4(L2)(CO)10] features metal–metal bonds, and no bridging carbonyls, whereas [Co2(CO)5(L1)] contains cobalt centers bridged by one or two carbonyl ligands. In either case, treatment with excess acetonitrile leads to disproportionation to the zwitterionic [Co[NNN](NCMe)2][Co(CO)4] units. The electronic structures of the complexes described above were studied with density functional theory. All the obtained bis(imino)pyridine complexes serve as catalysts for cyclotrimerization of methyl propiolate, albeit their reactivity is inferior compared with Co2(CO)8. [ABSTRACT FROM AUTHOR]

Herein we present platinum(iv) bioconjugates with polyarginine peptides as prospective prodrug delivery systems. Asymmetrical platinum(iv) complexes 3 were obtained via oxidation of parent platinum(ii) complexes 2 with N-bromosuccinimide (NBS) in the presence of succinic anhydride. The combination of these two oxidation reagents furnishes the platinum(iv) environment with two different axial ligands, one of which bears a free carboxylic acid. All platinum(ii) and (iv) compounds were characterized by FT-IR, ESI-MS, HPLC, 1H-, 13C- and 195Pt-NMR. Standard solid-phase peptide chemistry was used for the synthesis of polyarginine (R9) peptides. Coupling of the platinum complexes with peptides N-terminally afforded peptide monoconjugates, which were purified by semi-preparative HPLC and characterized by analytical HPLC and ESI-MS. Platinum(iv)–peptide bioconjugates as well as platinum(ii) and platinum(iv) complexes were tested as cytotoxic agents against two different human cancer cell lines (MCF-7, HepG2) and normal human fibroblasts cell lines (GM5657T). Preliminary in vitro data showed that all platinum(iv) complexes exhibit lower activity than their platinum(ii) precursors towards most cell lines. Interestingly, in the case of HepG2 cells, the Pt(iv)-(R)9-G-A-L bioconjugate (4a) showed even higher activity compared to the non-targeting platinum(iv) parent compound. [ABSTRACT FROM AUTHOR]

The electrophilic phosphonium cation (EPC) salt [(3,5-(CF3)2C6H3)3PF][B(C6F5)4] (2) is prepared via oxidation of the precursor phosphine with XeF2 and subsequent abstraction of fluoride with [Et3Si(tol)][B(C6F5)4]. The Lewis acidity of 2 is evaluated by experimental and computational methods and by preliminary catalysis testing. Exchange reactions of 2 and [(C6F5)3PF][B(C6F5)4] with their respective difluorophosphoranes are studied by 2D 19F–19F NOESY/EXSY and selective 1D 19F NMR exchange spectroscopy (SEXSY) experiments affording comparative rates of fluoride exchange. Collectively, although these data show that 2 is less Lewis acidic than [(C6F5)3PF][B(C6F5)4], the improved access to the P center of 2 provides a kinetic acceleration for fluoride exchange and catalysis where the transition states are more sterically demanding. [ABSTRACT FROM AUTHOR]

The electrophilic phosphonium cation (EPC) salt [(3,5-(CF3)2C6H3)3PF][B(C6F5)4] (2) is prepared via oxidation of the precursor phosphine with XeF2 and subsequent abstraction of fluoride with [Et3Si(tol)][B(C6F5)4]. The Lewis acidity of 2 is evaluated by experimental and computational methods and by preliminary catalysis testing. Exchange reactions of 2 and [(C6F5)3PF][B(C6F5)4] with their respective difluorophosphoranes are studied by 2D 19F–19F NOESY/EXSY and selective 1D 19F NMR exchange spectroscopy (SEXSY) experiments affording comparative rates of fluoride exchange. Collectively, although these data show that 2 is less Lewis acidic than [(C6F5)3PF][B(C6F5)4], the improved access to the P center of 2 provides a kinetic acceleration for fluoride exchange and catalysis where the transition states are more sterically demanding. [ABSTRACT FROM AUTHOR]

Tri-amidinate chloride complexes M[MeC(NiPr)2]3Cl [M = Zr (1), Hf (2)] have been prepared from MCl4 and lithium amidinate Li[MeC(NiPr)2]. The uncommon hepta-coordinated complexes Zr–Cl (1) and Hf–Cl (2) undergo metathesis reactions with 1 equiv. of MeLi and EtMgCl to give alkyl derivatives M[MeC(NiPr)2]3R [R = Me, M = Zr (3), Hf (4); R = Et, M = Zr (5), Hf (6)]. The dynamic behaviors of Zr–Cl (1) and Hf–Cl (2) in solution have been studied using variable-temperature 1H NMR (VT 1H NMR), giving activation parameters ΔH‡, ΔS‡, and ΔG‡ for several exchange processes in Zr–Cl (1) and Hf–Cl (2). 1H–15N gHMBC NMR spectroscopy gives the chemical shifts of the N atoms in 1–6. The 1H–15N gHMBC NMR spectra of 1–4 at elevated temperatures are needed to obtain signals. Crystal structures of Zr–Cl (1), Hf–Cl (2), Zr–Et (5), and Hf–Et (6) have been determined via X-ray diffraction. DART-MS studies of Zr–Cl (1) and Hf–Cl (2) in air give MS of 1–2, cations M[MeC(NiPr)2]3+ [M = Zr (7), Hf (8)], and hydroxyl complexes M[MeC(NiPr)2]3OH [M = Zr (9), Hf (10)]. In comparison, DART-MS spectra of 3–6 in air show only 7–8 and 9–10, indicating lability of the alkyl ligands and/or their fast hydrolysis by moisture. [ABSTRACT FROM AUTHOR]

Assembly of an active [FeFe]-hydrogenase requires dedicated maturation enzymes that generate the active-site H-cluster: the radical SAM enzymes HydE and HydG synthesize the unusual non-protein ligands – carbon monoxide, cyanide, and dithiomethylamine – while the GTPase HydF serves as a scaffold for assembly of the 2Fe subcluster containing these ligands. In the current study, enzymatically cluster-loaded HydF ([2Fe]F) is produced by co-expression with HydE and HydG in an Escherichia coli host followed by isolation and examination by FTIR and EPR spectroscopy. FTIR reveals the presence of well-defined terminal CO and CN− ligands; however, unlike in the [FeFe]-hydrogenase, no bridging CO is observed. Exposure of this loaded HydF to exogenous CO or H2 produces no significant changes to the FTIR spectrum, indicating that, unlike in the [FeFe]-hydrogenase, the 2Fe cluster in loaded HydF is coordinatively saturated and relatively unreactive. EPR spectroscopy reveals the presence of both [4Fe–4S] and [2Fe–2S] clusters on this loaded HydF, but provides no direct evidence for these being linked to the [2Fe]F. Using the chemical reactivity and FTIR data, a large collection of computational models were evaluated. Their scaled quantum chemical vibrational spectra allowed us to score various [2Fe]F structures in terms of their ability to reproduce the diatomic stretching frequencies observed in the FTIR experimental spectra. Collectively, the results provide new insights that support the presence of a diamagnetic, but spin-polarized FeI–FeI oxidation state for the [2Fe]F precursor cluster that is coordinated by 4 CO and 2 CN− ligands, and bridged to an adjacent iron–sulfur cluster through one of the CN− ligands. [ABSTRACT FROM AUTHOR]

This paper demonstrates the use of phosphinecarboxamide as a facile phosphorus precursor, which can be used alongside zinc acetate for the chemical vapour deposition (CVD) of adherent and crystalline zinc phosphide films. Thin films of Zn3P2 have a number of potential applications and phosphinecarboxamide is a safer and more efficient precursor than the highly toxic, corrosive and flammable phosphine used in previous CVD syntheses. [ABSTRACT FROM AUTHOR]

A new organo-tin complex has been synthesized and used as a single source precursor for the synthesis of SnSe nanosheets by the hot injection method and thin films by the aerosol assisted chemical vapor deposition (AACVD) method. The films were deposited on glass substrates at three different temperatures. The textural quality and preferential growth were found to be significantly altered by changes in the deposition temperature. Oleylamine capped nanosheets and the as-deposited thin films by AACVD were characterized by powder X-ray diffraction (p-XRD) and microscopic techniques. The thin films were also studied by Raman spectroscopy. The stoichiometry is marginally affected by temperature, and all films were slightly selenium deficient. The synthesized material was also evaluated for the photoelectrochemical (PEC) splitting of water. The PEC study revealed the bifunctional nature of the material, which can be applied for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), by switching the applied potential. [ABSTRACT FROM AUTHOR]

A series of Ni(ii), Pd(ii) and Pt(ii) complexes [ML][PF6]2 [L = L1, M = Ni (1), Pd (2), Pt (3); L = L2, M = Ni (4), Pd (5), Pt (6)] and [Pt(L2)(acac)] (7) have been prepared by the reactions of two tetradentate macrocyclic amine-NHC ligand precursors, [H2L1][PF6]2 and [H2L2][PF6]2, with Ni(OAc)2·4H2O, Pd(OAc)2 and Pt(acac)2 in the presence of NaOAc. Complex 7 is isolated along with 6 from the same reaction between [H2L2][PF6]2 and Pt(acac)2. There are two atropisomers in 1–3 and two achiral conformers in 4–6. The crystal structures of 1–3 and one conformer of 4–6 (4a–6a) have been determined by single-crystal X-ray diffraction studies. The metal ion is found to reside in the cavity of the macrocyclic ring and adopts a square-planar configuration. Detailed NMR studies including variable-temperature NMR spectroscopy reveal a dynamic interconverting process between two atropisomers of 1–3 in the solutions via a ring twisting mechanism. Two conformers in the equilibrated solution of 4–6, probably arising from the orientation of two amine N–H bonds with respect to the coordination plane, exchange slowly. Time-dependent 1H NMR spectra show that one conformer (4a–6a) in solution converts into the other (4b–6b) via the inversion of the nitrogen atom. [ABSTRACT FROM AUTHOR]

A novel synthetic approach for the synthesis of gold(iii) acetato, alkoxolato and alkynyl complexes was developed via the reactivity of gold(iii) trications containing the N,N-chelating ligand 2,2′-bipyridine and N,N,N-chelating ligand terpyridine through direct reactions with the protic precursors. This protocol avoids the gold(iii) chloride bond activation pathway commonly employed to access these functionalities. For example exposure of [LAu(iii)L′]OTf3 (L = N,N,N-terpyridine, L′ = 4-DMAP) to RH (R = OCH3, OAc, Ph-≡) results in the facile formation of the corresponding functionalised gold(iii) complexes [LAu(iii)R]OTf2. [ABSTRACT FROM AUTHOR]

A pair of thallium salen derivatives was synthesized and characterized for potential use as monitors (or taggants) or as models for Group 13 complexes for subterranean fluid flows. These precursors were isolated from the reaction of thallium ethoxide with N,N′-bis(3,5-di-tert-butylsalicylidene)-ethylenediamine (H2-salo-But), or N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-phenylenediamine (H2-saloPh-But). The products were identified by single crystal X-ray diffraction as: [((μ-O)2,κ1-(N)(N′)salo-But)Tl2] (1) and {[((μ-O)2saloPh-But)Tl2][((μ-O)2,κ1-(N)(N′)saloPh-But)Tl2]} (2). Both structures are similar, wherein each O atom of the salo moiety bridges the two Tl atoms, leading to a Tl…Tl interaction, which is further stabilized by an intramolecular π-bond with neighboring phenyl rings. For 1, an additional Tl…N interaction was solved for each metal center; whereas, for 2, one of the two molecules in the matrix has a weak Tl…N interaction but no bonding noted in the other molecule. Both Density Functional Theory (DFT) calculations and variable temperature solution 205Tl NMR studies of 1 and 2 further confirmed the Tl…Tl interaction. The UV-vis absorbance spectra of these compounds had an absorbance peak at 392 nm for 1 and a broad absorbance peak centered at 469 nm for 2, which were found to be in good agreement with the DFT calculated spectra that were dominated by the singlet state. Fluorescence emission and excitation studies reveal absorptions at 360 and 380 nm for 1 and 2, respectively, which are attributed to the Tl…Tl metal centers. To demonstrate practicality, fluorescence spectra of 1 and 2 were obtained using a handheld 405 nm cw laser pointer and portable spectrometer where compound 1 was found to glow 15 times brighter than compound 2. Only compound 1 was found to survive the simulated deep-well conditions explored, which was attributed to the Tl…N interaction noted for 1 but not for 2. [ABSTRACT FROM AUTHOR]

A unique trivalent manganese siloxide complex, blue-violet MnIIILi2Cl[(Ph2SiO)2O]2(THF)4·2THF (3) has been prepared by a straightforward two-step synthetic protocol. Lithiation of (Ph2SiOH)2O (1) followed by reaction with MnCl2(THF)2 gave the structurally remarkable Mn(ii) precursor MnIILi4Cl2[(Ph2SiO)2O]2(THF)5·2THF (2). Surprisingly, the final oxidation step could be achieved using KMnO4 in THF to provide the Mn(iii) species 3 in high yield (91%). Both title compounds were structurally characterized by single-crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

In this work, we reported a novel and slack rose-like metal organic precursor designed by coordinating p-phenylenediamine with cobalt ion. After subsequent pyrolysis and acid etching process, the as-prepared Co–N–C catalyst delivered a superior catalytic activity and long-term durability. Further applied in the Zn–air battery, it also displayed a comparable performance with 20% Pt/C. [ABSTRACT FROM AUTHOR]

A series of alkynyl gold(i) tri and tetratopic metallaligands of the type [Au3(C≡C–R)3(μ3-triphosphane)] (R = 2,2′-bipyridin-5-yl or C10H7N2, 2,2′:6′,2′′-terpyridin-4-yl or C15H10N3; triphosphane = 1,1,1-tris(diphenylphosphanyl)ethane or triphos, 1,3,5-tris(diphenylphosphanyl)benzene or triphosph) and [Au4(C≡C–R)4(μ4-tetraphosphane)] (R = C10H7N2, C15H10N3; tetraphosphane = tetrakis(diphenylphosphanylmethyl)methane or tetraphos, 1,2,3,5-tetrakis(diphenylphosphanyl)benzene or tpbz, tetrakis(diphenylphosphaneylmethyl)-1,2-ethylenediamine or dppeda) were obtained in moderate to good yields. All complexes could be prepared by a reaction between the alkynyl gold(i) polymeric species [Au(C≡C–R)]n and the appropriate polyphosphane. An alternative strategy that required the previous synthesis of the appropriate acetylacetonate precursors [Aun(acac)n(μn-polyphosphane)] (“acac method”) was assayed, nevertheless only the polyacac derivatives [Au3(acac)3(μ3-triphosphane)] (triphosphane = triphos and triphosph) and [Au4(acac)4(μ4-tetraphos)] could be isolated and characterized. All compounds were characterized by IR, multinuclear NMR spectroscopy and ESI(+) mass spectrometry. The X-ray crystal structure of complexes [Au4(C≡C–C10H7N2)4(μ4-tetraphos)] and [Au4(C≡C–C10H7N2)4(μ4-tpbz)] showed the involvement of all the gold atoms in close intramolecular Au…Au contact as well as intermolecular π stacking interactions between the aromatic rings of the polypyridyl ligands. The photophysical properties of the synthesized compounds were carefully studied and used as a probe of their possible use as multidentate ligands for Cu(i) and Zn(ii). The UV-Vis speciation studies of the complexation reactions were conducted via metal titration and, in most cases the dangling units of the ligand were found to behave in a fairy independent manner. While in the case of Cu(i) multiple equilibria exist in solution a single complex is detected for Zn(ii) under the conditions studied. [ABSTRACT FROM AUTHOR]

Two series of co-polymers with the general formula [B(C2H4SiCH3(NH)x(NCH3)y)3]n, i.e., composed of C2H4SiCH3(NH)x and C2H4SiCH3(NCH3)y (C2H4 = CHCH3, CH2CH2) building blocks in a well defined x : y ratio, have been synthesized by hydroboration of dichloromethylvinylsilane with borane dimethyl sulfide followed by successive reactions with lithium amide and methylamine according to controlled ratios. The role of the chemistry behind their syntheses has been studied in detail by solid-state NMR, FT-IR and elemental analyses. Then, the intimate relationship between the chemistry and the melt-spinnability of these polymers was discussed. By keeping x = 0.50 and increasing y above 0.50, i.e., obtaining methylamine excess, the co-polymers contained more ending groups and especially more tetracoordinated boron, thus allowing tuning very precisely the chemical structure of the preceramic polymer in order to meet the requirements for melt-spinning. The curing treatment under ammonia at 200 °C efficiently rendered the green fibers infusible before their subsequent pyrolysis under nitrogen at 1000 °C to generate Si–B–C–N ceramic fibers. Interestingly, it could be possible to produce also low diameter hollow fibers with relatively high mechanical properties for a further exploration as membrane materials. [ABSTRACT FROM AUTHOR]

The cobalt–nitrosyl complex [Co(NO)(L3)] is supported by a highly hindered tridentate nitrogen ligand, hydrotris(3-tertiary butyl-5-isopropyl-1-pyrazolyl)borate (denoted as L3−), and shows a linear Co–N–O unit. This complex was prepared by the reaction of the potassium salt of L3− with the cobalt–nitrosyl precursor [Co(NO)2(tmeda)](BPh4) (tmeda = N,N,N,′N′-tetramethylethylenediamine). The obtained cobalt–nitrosyl complex as well as the corresponding products from the reaction with dioxygen, [Co(η2-O2N)(L3)] and [Co(η2-O2NO)(L3)], were characterised by X-ray crystallography and a number of spectroscopic methods including IR/far-IR, UV-Vis, and NMR spectroscopy. We also performed MCD measurements and DFT calculations to further elucidate the electronic structure of [Co(NO)(L3)] and the optical properties of the complex. The MCD spectra reveal two NO-to-Co charge-transfer transitions with strong excited state displacements that give rise to vibrational progressions in the MCD spectra, indicative of a very covalent Co–NO bond. These results provide new insight into the properties of the Co–NO bond and the electron distribution in the complex, which is best described as [CoII(NO−)(L3)]. [ABSTRACT FROM AUTHOR]

YBCO samples with different microstructures were prepared after the thermal treatment of a precursor previously obtained by autocombustion. A drastic influence of the particle size on the magnetic behavior of the samples was observed. Thus, particles smaller than 110 nm do not exhibit superconducting properties and for those ranging around 200 nm the diamagnetic signal characteristic of the superconductivity at low temperature disappears in a large applied magnetic field. Particles larger than 300 nm do not exhibit the particle size effect. Accompanying such a phenomenon, an increase of the superconducting critical temperature is observed with the augmentation of the particle size, the lowest value being 18 K which corresponds to 110 nm particles. [ABSTRACT FROM AUTHOR]

This work reports two new silver metalorganic precursors for the chemical vapor deposition of Ag metallic coatings. Both precursors are based on β-diketonate adducts, namely, Ag(hfac)(L) (H-hfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione), where L is 1,10-phenanthroline (phen) or 2,5,8,11-tetraoxadodecane (triglyme). Using these ligands, the designed precursors have better solubility in alcoholic solvents and are less toxic and costly than previously reported ones. The new precursors have been characterized and their crystallographic structure solved. With the new triglyme precursor, [Ag(triglyme)2]+[Ag(hfac)2]−, pure metallic Ag coatings made of Ag nanoparticles about 20 nm in diameter were succesfully deposited on glass and Si substrates using Aerosol Assisted Metalorganic CVD (AA-CVD). [ABSTRACT FROM AUTHOR]

To grow films of Cu2O, bis-(dimethylamino-2-propoxide)Cu(ii), or Cu(dmap), is used as an atomic layer deposition precursor using only water vapor as a co-reactant. Between 110 and 175 °C, a growth rate of 0.12 ± 0.02 Å per cycle was measured using an in situ quartz crystal microbalance (QCM). X-ray photoelectron spectroscopy (XPS) confirms the growth of metal–oxide films featuring Cu(i). [ABSTRACT FROM AUTHOR]

A series of nickel(ii) aryloxide ([Ni(OAr)2(py)x]) precursors was synthesized from an amide-alcohol exchange using [Ni(NR2)2] in the presence of pyridine (py). The H-OAr selected were the mono- and di-ortho-substituted 2-alkyl phenols: alkyl = methyl (H-oMP), iso-propyl (H-oPP), tert-butyl (H-oBP) and 2,6-di-alkyl phenols (alkyl = di-iso-propyl (H-DIP), di-tert-butyl (H-DBP), di-phenyl (H-DPhP)). The crystalline products were solved as solvated monomers and structurally characterized as [Ni(OAr)2(py)x], where x = 4: OAr = oMP (1), oPP (2); x = 3: OAr = oBP (3), DIP (4); x = 2: OAr = DBP (5), DPhP (6). The excited states (singlet or triplet) and various geometries of 1–6 were identified by experimental UV-vis and verified by computational modeling. Magnetic susceptibility of the representative compound 4 was fit to a Curie Weiss model that yielded a magnetic moment of 4.38(3)μB consistent with a Ni2+ center. Compounds 1 and 6 were selected for decomposition studied under solution precipitation routes since they represent the two extremes of coordination. The particle size and crystalline structure were characterized using transmission electron microscopy (TEM) and powder X-ray diffraction (PXRD). The materials isolated from 1 and 6 were found by TEM to form irregular shape nanomaterials (8–15 nm), which by PXRD were found to be Ni0 hcp (PDF: 01-089-7129) and fcc (PDF: 01-070-0989), respectively. [ABSTRACT FROM AUTHOR]

PrLuO3 interlanthanides were prepared at temperatures ranging from 800 °C to 1600 °C using hydrothermally-derived precursors. The chemical reactions observed include the conversion and segregation of Pr(OH)3 and LuO(OH), respectively, into PrO2 and Lu2O3 cubic oxides below 1200 °C, followed by the production of a mixture of hexagonal P63/mmc and orthorhombic Pnma PrLuO3 phases at 1400 °C. Phase-pure orthorhombic PrLuO3 was obtained at 1600 °C, which was corroborated by Raman and micro far-infrared spectroscopic analyses. Photoluminescence, colorimetric and lifetime measurements were carried out in PrLuO3 samples. Dominant emission verified in samples calcined at 1400 °C corresponds to the hypersensitive 3P0→3F2 transition with a color purity of 97% (decay times of 12 μs and 3 μs), while emissions for the phase-pure samples correspond to the 3P0→3H6 and 3P0→3H5 transitions with a color purity of 94% (a single luminescence lifetime of 12 μs). The optical properties of PrLuO3 interlanthanides thereby suggest that they can be used as luminescent materials in both structural arrangements. [ABSTRACT FROM AUTHOR]

Molecular engineering of seven closely related zinc ketoiminates, namely, [Zn(dapki)2], [Zn(daeki)2], [Zn(epki)2], [Zn(eeki)2], [Zn(mpki)2], [Zn(meki)2], and [Zn(npki)2], leads to the optimisation of precursor thermal properties in terms of volatilisation rate, onset of volatilisation, reactivity and thermal stability. The influence of functional groups at the imine side chain of the ligands on the precursor properties is studied with regard to their viability as precursors for atomic layer deposition (ALD) of ZnO. The synthesis of [Zn(eeki)2], [Zn(epki)2] and [Zn(dapki)2] and the crystal structures of [Zn(mpki)2], [Zn(eeki)2], [Zn(dapki)2] and [Zn(npki)2] are presented. From the investigation of the physico-chemical characteristics, it was inferred that all compounds are monomeric, volatile and exhibit high thermal stability, all of which make them promising ALD precursors. Compound [Zn(eeki)2] is in terms of thermal properties the most promising Zn-ketoiminate. It is reactive towards water, possesses a melting point of 39 °C, is stable up to 24 days at 220 °C and has an extended volatilisation rate compared to the literature known Zn-ketoiminates. It demonstrated self-saturated, water assisted growth of zinc oxide (ZnO) with growth rates in the order of 1.3 Å per cycle. Moreover, it displayed a broad temperature window from TDep = 175–300 °C and is the first report of a stable high temperature (＞200 °C) ALD process for ZnO returning highly promising growth rates. [ABSTRACT FROM AUTHOR]

The synthesis and photophysical characterization of a new family of luminescent water-soluble ionic iridium(iii) complexes of the general formula [(ppy)2Ir(bpy)]X are reported. The Ir(iii) complexes incorporate a cyclometalated 2-phenylpyridine (ppy), the ancillary ligand 2,2′-bipyridyl (bpy) and different counterions (X− = EtO−, OH−, EtOCH2CO2−, MeOCH2CO2−). These complexes were obtained starting from the cyclometalated Ir(iii) chloro-bridged dimer [(ppy)2Ir(μ-Cl)]2, for the first time synthesized through a new microwave assisted synthetic procedure, and subsequently converted into the corresponding hydroxy-bridged dimer [(ppy)2Ir(μ-OH)]2. The latter was eventually used as a sole reagent for the synthesis of all the reported complexes by simply varying the nature of the reaction solvent from water to alcohols and glycol ethers. This study demonstrates the versatility of the [(ppy)2Ir(μ-OH)]2 complex as a precursor to water soluble ionic Ir(iii) complexes. Indeed, [(ppy)2Ir(μ-OH)]2 has shown its peculiar chemical reactivity due to both a strong base character and an unexpected oxidative ability towards the alcoholic function of glycol ethers. All the synthesized complexes exhibit, in water solution, an orange emission centred at 606 nm. Moreover, all complexes display the ability to give rise to gel phases in water upon increasing their concentration, and the photophysical study evidenced the various interactions governing the gelification process. The water-solubility of these new luminescent Ir(iii) complexes makes them potentially useful in bio-related systems. [ABSTRACT FROM AUTHOR]

A series of borocations have been synthesised from the addition of haloboranes to synthetically accessible N,N′-1,4-diazabutadiene precursors, which are derived from commercially available anilines. The synthesis and structural studies of the borocations are described. [ABSTRACT FROM AUTHOR]

A general synthesis of novel platinum(ii) complexes bearing two different, cis-oriented, N-heterocyclic carbene (NHC) ligands is presented. Easily accessible cis-[PtII(NHC)(DMSO)] precursor complexes were converted to either cis-[PtII(NHC)2Cl2] complexes such as 5a and 5b, or to novel mixed cis-[PtII(NHC)1(NHC)2Cl2] complexes such as 5c–h by successive introduction of the individual carbene ligands. The ‘symmetric’ complexes 5a and 5b were also converted to cationic cis-[PtII(NHC)2(PPh3)Cl]+Cl− complexes 8a and 8b. The structures of the ten new complexes, comprising benzylated and alkylated imidazol-2-ylidene ligands, were analysed by 1H, 13C and 195Pt NMR spectroscopy and also by X-ray diffraction for 5a, 5d, 5h, and 8a. The neutral complexes 5 were cytotoxic against a panel of seven human cancer cell lines with IC50 values in the low micromolar range, while the cationic complexes 8 reached even nanomolar IC50 values. Complex 5h carrying the substitution pattern of the natural antitumoral agent Combretastatin A-4 showed a conspicuous specificity for cancer cell lines sensitive to this drug. In electrophoretic mobility shift assays, the cis-biscarbene complexes 5b and 8b led to an unwinding or aggregation of plasmid DNA, while the trans-biscarbene complex 1b showed no such effect. [ABSTRACT FROM AUTHOR]

The carbene derived from (1R,3S)-camphoric acid was used to prepare the borane adduct with Piers’ borane 7. Subsequent hydride abstraction gave the borenium cation 8. Adducts with 9-BBN and the corresponding (1R,3S)-camphoric acid-derived carbene bearing increasingly sterically demanding N-substituents (R = Me 9, Et 10, i-Pr 11) and the corresponding borenium cations 12–14 were also prepared. These cations were not active as catalysts in hydrogenation, although 9–11 were shown to undergo carbene ring expansion reactions at 50 °C to give species 15–17. The IBOX-carbene precursors 18 and 19 derived from amino alcohols (S)-valinol and (S)-tert-leucinol (R = i-Pr, t-Bu) were used to prepare borane adducts 20–23. Reaction of the carbenes 1,3-dimethylimidazol-2-ylidene (IMe), 1,3-di-iso-propylimidazol-2-ylidene (IPr) 1-benzyl-3-methylimidazol-2-ylidene (IBnMe), 1-methyl-3-phenylimidazol-2-ylidene (IPhMe) and 1-tert-butyl-3-methylimidazol-2-ylidene (ItBuMe) with diisopinocampheylborane (Ipc2BH) gave chiral adducts: (IMe)(Ipc2BH) 24, (IPr)(Ipc2BH) 25, (IBnMe)(Ipc2BH) 26, (IPhMe)(Ipc2BH) 27, and (ItBuMe)(Ipc2BH) 28. Triazolylidene-type adducts including the (10)-phenyl-9-borabicyclo [3.3.2]decane adduct of 1,3,4-triphenyl-1H-1,2,3-triazolium, rac-29 and the 9-BBN derivative of (S)-2-amino-2′-methoxy-1,1′-binaphthalene-1,2,3-triazolium 34a/b were also prepared. In catalytic studies of these systems, while several species were competent catalysts for imine reduction, in general, low enantioselectivities, ranging from 1–20% ee, were obtained. The implications for chiral borenium cation catalyst design are considered. [ABSTRACT FROM AUTHOR]

A series of organic derivatives of magnesium borohydride, including Mg(BH4)2·1.5DME (DME = 1,2-dimethoxyethane) and Mg(BH4)2·3THF (THF = tetrahydrofuran) solvates and three mixed-cation borohydrides, [Cat]2[Mg(BH4)4], [Cat] = [Me4N], [nBu4N], [Ph4P], have been characterized. The phosphonium derivative has been tested as a precursor for synthesis of inorganic mixed-metal borohydrides of magnesium, Mx[Mg(BH4)2+x], M = Li–Cs, via a metathetic method. The synthetic procedure has yielded two new derivatives of heavier alkali metals M3Mg(BH4)5 (M = Rb, Cs) mixed with amorphous Mg(BH4)2. Thermal decomposition has been studied for both the organic and inorganic magnesium borohydride derivatives. Amorphous MgB2 has been detected among the products of the thermal decomposition of the solvates studied, together with organic and inorganic impurities. [ABSTRACT FROM AUTHOR]

A new phase of oxyhydride NdNiOxHy with a defect-fluorite structure was obtained by a soft chemical reaction of NdNiO3 epitaxial thin films on a substrate of SrTiO3 (100) with CaH2. The epitaxial relationship of this phase relative to SrTiO3 could be controlled by changing the reaction temperature. At 240 °C, NdNiOxHy grew with a [001] orientation, forming a thin layer of infinite-layer NdNiO2 at the interface between the NdNiOxHy and the substrate. Meanwhile, a high-temperature reaction at 400 °C formed [110]-oriented NdNiOxHy without NdNiO2. [ABSTRACT FROM AUTHOR]

We have synthesized a new series of azolium cyclophanes and used them as precursors of inherently luminescent dinuclear Au(i)–N-heterocyclic carbene (NHC) complexes. The azolium cyclophanes contained two azolium groups (either imidazolium or benzimidazolium), an o-xylyl group, and an alkyl linker chain (either C2, C3 or C4). All of the azolium cyclophanes were characterised by X-ray diffraction studies and VT NMR studies, and all were fluxional in solution on the NMR timescale. The C3- and C4-linked azolium cyclophanes served as precursors of Au2L22+ complexes (L is a cyclophane bis(NHC) ligand). Due to the unsymmetrical nature of the azolium cyclophanes, the Au2L22+ complexes each existed as cis and trans isomers. X-ray diffraction studies showed that the Au2L22+ complexes had short intramolecular Au…Au distances, in the range 2.9–3.3 Å, suggestive of an aurophilic attraction, presumably as a consequence of the geometrical constraints imposed by the cyclophane bis(NHC) ligands. The complexes having the shortest Au…Au distances (i.e., those based on C3-linked cyclophanes) exhibited intense luminescence in solution. The uptake of one of the dinuclear Au–NHC complexes by tumorigenic cells, and its subsequent distribution and toxicity in the cells, was monitored by luminescence microscopy over 6 h and proliferation measurements, respectively. [ABSTRACT FROM AUTHOR]

Here we report the growth of novel transition metal–organic thin-film materials consisting of manganese or cobalt as the metal component and terephthalate as the rigid organic backbone. The hybrid thin films are deposited by the currently strongly emerging atomic/molecular layer deposition (ALD/MLD) technique using the combination of a metal β-diketonate, i.e. Mn(thd)3, Co(acac)3 or Co(thd)2, and terephthalic acid (1,4-benzenedicarboxylic acid) as precursors. All the processes yield homogeneous and notably smooth amorphous metal–terephthalate hybrid thin films with growth rates of 1–2 Å per cycle. The films are stable towards humidity and withstand high temperatures up to 300 or 400 °C under an oxidative or a reductive atmosphere. The films are characterized with XRR, AFM, GIXRD, XPS and FTIR techniques. [ABSTRACT FROM AUTHOR]

Here, we demonstrate a green and environment-friendly pyrolysis route for the synthesis of metal-rich sulphide embedded in an N-doped carbon (NC) framework in the absence of sulphide ions (S2−). The metal–chelate complex (tris(ethylenediamine) metal(ii) sulfate) serves as a new and single source precursor for the synthesis of earth abundant and non-precious hybrid structures such as metal-rich sulphides Co9S8@NC and Ni3S2@NC when MII = Co2+ and Ni2+ and counter sulphate (SO42−) ions are the source of S. Both the hybrids show superior OER activity as compared to commercial RuO2. [ABSTRACT FROM AUTHOR]

The synthesis and characterisation of several sodium zincate complexes are reported. The all-alkyl monomeric sodium zincate, (PMEDTA)·Na(μ-CH2SiMe3)ZntBu22, is prepared by combining equimolar quantities of tBu2Zn, nBuNa and PMDETA (N,N,N′,N′′,N′′-pentamethyldiethylenetriamine)]. A similar approach was used to prepare and isolate the unusual dimeric zincate [(PMEDTA)·Na(μ-nBu)ZntBu2]23. When an equimolar mixture of nBuNa, tBu2Zn and TMP(H) (2,2,6,6-tetramethylpiperidine) is combined in hexane, the hetero-tri-leptic TMP(H)-solvated zincate (TMPH)Na(μ-TMP)(μ-nBu)ZntBu 4 results. Complex 4 can also be prepared using a rational approach [i.e., utilising two molar equivalents of TMP(H)]. When TMEDA is reacted with an equimolar mixture of nBuNa, tBu2Zn and TMP(H), the monomeric sodium zincate (TMEDA)Na(μ-TMP)(μ-nBu)ZntBu 5 was obtained – this complex is structurally similar to the synthetically useful relation (TMEDA)·Na(μ-TMP)(μ-tBu)Zn(tBu) 1. By changing the sodium reagent used in the synthesis of 5, it was possible to prepare (TMEDA)Na(μ-TMP)(μ-Me3SiCH2)ZntBu 6. By reacting 5 with cis-DMP(H) (cis-2,6-dimethylpiperidine), the zincate could thermodynamically function as an amide base, to give the transamination product (TMEDA)Na(μ-cis-DMP)(μ-nBu)ZntBu 7, although no crystals could be grown. However, when HMDS(H) (1,1,1,3,3,3-hexamethyldisilazane) or PEA(H) [(+)-bis[(R)-1-phenylethyl]amine] is reacted with 5, crystalline (TMEDA)Na(μ-HMDS)(μ-nBu)ZntBu 8 or (TMEDA)Na(μ-PEA)(μ-nBu)ZntBu 9 is isolated respectively. With PNA(H) (N-phenylnaphthalen-1-amine) the reaction took a different course and resulted in the formation of the dimeric sodium amide complex [(TMEDA)Na(PNA)]210. When reacted with benzene, it appears that a TMEDA-free variant of 5 functions thermodynamically as an nBu base to yield the previously reported (TMEDA)Na(μ-TMP)(tBu)Zn(μ-C6H4)Zn(tBu)(μ-TMP)Na(TMEDA) 11. Finally when reacted with TEMPO (2,2,6,6-tetramethylpiperidinyloxy), 5 undergoes a single electron transfer reaction to form (TMEDA)Na(μ-TMP)(μ-TEMPO)ZnnBu 12. [ABSTRACT FROM AUTHOR]

The new area of lithio(thiocyanato)cuprates has been developed. Using inexpensive, stable and safe CuSCN for their preparation, these complexes revealed Lipshutz-type dimeric motifs with solvent-dependent point group identities; planar, boat-shaped and chair shaped conformers are seen in the solid state. In solution, both Lipshutz-type and Gilman structures are clearly seen. Since the advent in 2007 of directed ortho cupration, effort has gone into understanding the structure-reactivity effects of amide ligand variation in and alkali metal salt abstraction from Lipshutz-type cuprates such as (TMP)2Cu(CN)Li2(THF) 1 (TMP = 2,2,6,6-tetramethylpiperidide). The replacement of CN− with SCN− is investigated presently as a means of improving the safety of lithium cuprates. The synthesis and solid state structural characterization of reference cuprate (TMP)2Cu(CN)Li2(THP) 8 (THP = tetrahydropyran) precedes that of the thiocyanate series (TMP)2Cu(SCN)Li2(L) (L = OEt29, THF 10, THP 11). For each of 9–11, preformed TMPLi was combined with CuSCN (2 : 1) in the presence of sub-stoichiometric Lewis base (0.5 eq. wrt Li). The avoidance of Lewis basic solvents incurs formation of the unsolvated Gilman cuprate (TMP)2CuLi 12, whilst multidimensional NMR spectroscopy has evidenced the abstraction of LiSCN from 9–11 in hydrocarbon solution and the in situ formation of Gilman reagents. The synthetic utility of 10 is established in the selective deprotometalation of chloropyridine substrates, including effecting transition metal-free homocoupling in 51–69% yield. [ABSTRACT FROM AUTHOR]

Assembly of cucurbit[6] and a {Cd2Ge8V12O48} cluster produced two rotaxane-shaped and polyrotaxane-shaped solids by changing the ratio of starting precursors in the system. The high oxygen density of the polyoxoanion surface provides active sites to extend a single rotaxane-shaped hybrid 1 to a 1D polyrotaxane-shaped hybrid 2. This construction strategy may afford an entirely new methodology for polyoxometalate-based hybrid chemistry. [ABSTRACT FROM AUTHOR]

Phosphorylation reactions of an iron(ii) dichloroclathrochelate FeBd2(Cl2Gm)(BF)2 (where Bd2− and Cl2Gm2− are α-benzildioxime and dichloroglyoxime dianions, respectively) with diphenylphosphine oxide and diethyl thiophosphite were performed under phase-transfer conditions. In the case of diethyl thiophosphite as a P-nucleophile, the best yields were obtained in the dichloromethane–50% NaOH aqueous solution–5 mol% triethylbenzylammonium chloride (TEBAC) system. The use of different molar ratios of a macrobicycle precursor and this thiophosphorylating agent allowed us to obtain both the mono- and the diphosphorylated cage complexes. Nucleophilic substitution with diphenylphosphine oxide was performed in the K2CO3–acetonitrile–5 mol% TEBAC system, giving only the corresponding monophosphorylated iron(ii) complex in high yield even in the presence of an excess of this P-nucleophile. The phosphorus(v)-containing clathrochelate product was reduced with an excess of silicoform to give an iron(ii) macrobicycle with an inherent diphenylphosphine group in an almost quantitative yield, which was then characterized by 31P{1H} NMR and single-crystal X-ray diffraction; it easily undergoes re-oxidation to the initial clathrochelate. The synthesized phosphorus(v)-containing cage complexes were characterized using elemental analysis, MALDI-TOF mass, IR, UV-Vis, 1H, 11B, 13C{1H}, 19F{1H} and 31P{1H} NMR spectra, and by single-crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

Ultra-thin nanosheets (2–6 nm) of the (Y1−xEux)2(OH)5NO3·nH2O layered rare-earth hydroxide (LRH), directly crystallized without exfoliation were employed for the first time as a sacrificial precursor to synthesize (Y1−xEux)PO4 orthophosphate red phosphors via nano-conversion, and anion exchange of both the hydroxyls and NO3− in the LRH with the phosphate ions from diammonium hydrogen phosphate ((NH4)2HPO4) is discussed. Detailed characterization of the materials was performed by the combined techniques of XRD, FTIR, TG/DSC, FE-SEM, HR-TEM, and photoluminescence spectroscopy. The (Y1−xEux)PO4 phosphors, with crystallite sizes of up to ∼20 nm, were found to exhibit stronger 5D0→7F2 (621 nm) than 5D0→7F1 (595 nm) emissions under charge transfer excitation (236 nm) owing to the nano-size effect. The optimal Eu3+ content was determined to be ∼10 at% (x = 0.10), and concentration quenching of luminescence was analyzed to result from exchange interactions. The effects of the Eu3+ content and annealing temperature on the structural features and luminescence properties of the (Y1−xEux)PO4 nanophosphors were discussed in detail, including emission intensity, the asymmetry factor of luminescence, fluorescence lifetime, and CIE chromaticity coordinates. [ABSTRACT FROM AUTHOR]

Luminescent B–N containing conjugated ladder compounds are prepared by directed electrophilic aromatic substitution. Negishi cross-coupling reaction of 2,7-dibromo-9,9-dihexylfluorene with 6-methylpyridin-2-yl(pivaloyloxy)zinc furnishes the dipyridylfluorene precursor (1) in 44% yield. Compound 1 is then subjected to electrophilic borylation with BBr3 in the presence of iPr2NEt as a bulky base to give the tetra-coordinate ladder-type organoboron species 2-Br. Arylation of 2-Br is accomplished by addition of Ph2Zn or C6F5Cu in toluene furnishing the targeted bis(pentafluorophenyl)borane and diphenylborane species 2-Ar (Ar = Ph, C6F5) in 53 and 44% yield respectively. The products show a strong blue emission and undergo multi-step reversible reduction and oxidation processes. The effect of fluorination of the pendant aryl groups on the electronic structure is further examined by DFT methods. [ABSTRACT FROM AUTHOR]

The reaction of the phenylene-bridged precursor (1,4-C6H4)[N(PCl2)2]2 with tBuNH2 in the presence of Et3N gives the new ligand precursor (1,4-C6H4)[N(μ-NtBu)2(PNHtBu)2]2, deprotonation of which with Bu2Mg gives the novel tetraanion [(1,4-C6H4){N(μ-NtBu)2(PNtBu)2}2]4−. [ABSTRACT FROM AUTHOR]

The reaction of the phenylene-bridged precursor (1,4-C6H4)[N(PCl2)2]2 with tBuNH2 in the presence of Et3N gives the new ligand precursor (1,4-C6H4)[N(μ-NtBu)2(PNHtBu)2]2, deprotonation of which with Bu2Mg gives the novel tetraanion [(1,4-C6H4){N(μ-NtBu)2(PNtBu)2}2]4−. [ABSTRACT FROM AUTHOR]

This study presents a new type of precursor, mechanical mixtures of metal oxides (MOs) and phosphorus pentoxide (P2O5) are used to synthesize Ni2P, Co2P and MoP phosphides by the H2 reduction method. In addition, this is first report of common solid-state P2O5 being used as a P source for the synthesis of metal phosphides. The traditional precursors are usually prepared via a complicated preparation procedure involving dissolution, drying and calcination steps. However, these novel MOs/P2O5 precursors can be obtained only by simple mechanical mixing of the starting materials. Furthermore, unlike the direct transformation from amorphous phases to phosphides, various specific intermediates were involved in the transformation from MOs/P2O5 to phosphides. It is worthy to note that the dispersions of Ni2P, Co2P and MoP obtained from MOs/P2O5 precursors were superior to those of the corresponding phosphides prepared from the abovementioned traditional precursors. It is suggested that the morphology of the as-prepared metal phosphides might be inherited from the corresponding MOs. Based on the results of XRD, XPS, SEM and TEM, the formation pathway of phosphides can be defined as MOs/P2O5 precursors → complex intermediates (metals, metal phosphates and metal oxide-phosphates) → metal phosphides. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride (h-BN) attracts considerable interest because its structure is similar to that of carbon graphite while it displays different properties which are of interest for environmental and green technologies. The polar nature of the B–N bond in sp2-bonded BN makes it a wide band gap insulator with different chemistry on its surface and particular physical and chemical properties such as a high thermal conductivity, a high temperature stability, a high resistance to corrosion and oxidation and a strong UV emission. It is chemically inert and nontoxic and has good environmental compatibility. h-BN also has enhanced physisorption properties due to the dipolar fields near its surface. Such properties are closely dependent on the processing method. Bottom-up approaches consist of transforming molecular precursors into non-oxide ceramics with retention of the structural units inherent to the precursor molecule. The purpose of the present review is to give an up-to-date overview on the most recent achievements in the preparation of h-BN from borazine-based molecular single-source precursors including borazine and 2,4,6-trichloroborazine through both vapor phase syntheses and methods in the liquid/solid state involving polymeric intermediates, called the Polymer-Derived Ceramics (PDCs) route. In particular, the effect of the chemistry, composition and architecture of the borazine-based precursors and derived polymers on the shaping ability as well as the properties of h-BN is particularly highlighted. [ABSTRACT FROM AUTHOR]

In this work, we analyzed the effects of subtle changes in the synthetic conditions and synthetic parameters on the resulting size, shape, monodispersity, crystallinity and magnetic properties of iron oxide nanocrystals (IONCs) obtained through a modified one pot method for the production of mainly cubic-shaped nanoparticles (NPs). Cubic, octahedral and cuboctahedral shapes with different sizes and monodispersity could be obtained by slightly changing the stabilizer/precursor molar ratio, the precursor concentration, the reaction time and temperature and/or the heating rate. Their physical properties were evaluated using high-resolution transmission electron microscopy (HRTEM), X-ray powder diffraction (XRD), selected-area electron diffraction (SAED) and a superconducting quantum interference (SQUID) device. It was found that monodisperse cubic nanocrystals from ca. 25 to 94 nm could be obtained either by changing the precursor concentration, the heating rate or the reaction time. These cubic nanocrystals were ferrimagnetic in the whole temperature rage analyzed, with saturation magnetization values even larger than those of bulk magnetite. In addition, slightly truncated octahedral NPs could be achieved at relatively large heating ramp rates, whereas cubooctahedral NPs were derived by simply increasing the stabilizer/precursor molar ratio. The saturation magnetization of both types of NPs was slightly lower than the cubic ones, but they were still ferrimagnetic in the whole temperature range analyzed. Moreover, transfer to aqueous solution was possible by a ligand exchange with dimercaptosuccinic acid (DMSA) providing, at the same time, chemical groups for additional functionalization if required. The DMSA-coated cubic IONCs were fairly stable in culture medium, allowing their internalization by different cell types. The NPs inside the cells were located in the cytoplasm and most of them showed a perinuclear distribution. Moreover, a great cytocompatibility in a large range of particle concentrations was observed without the induction of morphological changes in the cultured cells. [ABSTRACT FROM AUTHOR]

7-Phosphanorbornene sulfides were used as [RP = S] precursors. The reaction of these precursors with [M(PPh3)4] (M = Pd, Pt) yields star-like M4 clusters in which the central core is coated by three RP = S units acting as 4-electron μ2-P, η2-P = S ligands. The Pd cluster displays both stability and catalytic activity in the Suzuki-Miyaura reaction. DFT analysis suggests that a mononuclear [η2-RP = S]Pd(PPh3) complex is involved in the formation of the Pd4 clusters. [ABSTRACT FROM AUTHOR]

Solvothermal methods have been widely used to synthesize different kinds of materials. However, only little is known about how precursor solutions react to form solid precipitates via this method. In the present study, in situ microcalorimetry is first used to investigate the formation mechanism under solvothermal conditions, where ZnFe2O4 synthesized using a solvothermal method was selected as the model sample. Some novel results are obtained, such as with the experimental temperature increase, (1) the homogeneous solution transforms to a gel containing amorphous Fe2(C2H4O2)3 and ZnC2H4O2, and NaNO3 crystals; (2) the gel dissolves; (3) α-(Fe,Zn)OOH and α-Fe2O3 are synthesized; (4) the α-(Fe,Zn)OOH transforms to α-Fe2O3; (5) Fe2+ is formed at about 159 °C, which acts as a catalyst for the formation of Fe3O4; (6) the Fe3O4 crystals are synthesized at about 200 °C; (7) the Fe3O4 is transformed to the ZnFe2O4 with the help of NO3−, and the reaction was kept at 200 °C for about 20 h. This study shows a facile in situ method for the investigation of reaction processes of solvothermal methods. [ABSTRACT FROM AUTHOR]