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1.
Chem Commun (Camb) ; 56(57): 7893-7896, 2020 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-32524101

RESUMO

The reaction of the bis(methoxy)-2-pyridyl-phosphine (MeO)2P(2-py) (1) with [Ni(MeCN)6](BF4)2 leads to the unexpected single-step reduction of NiII and the formation of a tetrahedral nickel(0) complex [{(MeO)2P(2-py-H)}2{(MeO)2P(2-py)}2Ni](BF4)2 (2). The redox activity is probably induced by the decomposition of the tetrafluoroborate anion; NMR spectroscopic studies point towards a fluoride-assisted oxidation of the 2-pyridyl-phosphine ligand, with associated reduction of the metal.

2.
Nanotechnology ; 31(35): 355201, 2020 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-32408277

RESUMO

TiO2 nanowires with high transparency and good ion storage capacity were explored as the charge-balancing layers for assembling electrochromic devices (ECDs). Increase thickness of TiO2 nanowires layer lowers the driving potential of the entire ECDs accompanied with reduced potential at the EC layer electrode, which further leads to decreased optical contrast and switching speed of the ECDs. Meanwhile, it can be found that the EC layer electrodes possess larger charge densities than those of TiO2 nanowire electrodes during the electrochemical redox process of these ECDs. However, the intrinsic injection and extraction charge densities of each single electrode are similar, which appears that the intrinsic charge balance of EC layer and TiO2 nanowires electrodes play more important role in the cycling stability of the ECDs. ECD with an optimum thickness of the TiO2 nanowires layer exhibits good electrochromic properties in term of high optical contrast (∼45%), fast switching speed (3.23 s) and excellent cycling stability (which has nearly no decay after 5000 cycles). This study explores the effects of thickness of TiO2 Nanowires layer on electrode potentials and electrochromic properties of electrochromic devices (ECDs), providing a potentially new direction for the preparation of ECDs with good integrated performance.

3.
ChemSusChem ; 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32413249

RESUMO

A new green synthetic route to tris[4-(3,4-ethylenedioxythiophene)phenyl]amine (TEPA) monomer has been developed and the molecular structure of TEPA has been determined by using single-crystal XRD. Solution-processable nanoporous poly{tris[4-(3,4-ethylenedioxythiophene)phenyl]amine} (PTEPA) is prepared by a chemical oxidative polymerization in a microemulsion. Based on the distorted structure of TEPA in the solid state, it is proposed that dendritic PTEPA has a distorted 3 D conformation with multiple twisted channels and pores that are narrowed and blocked by bifurcation and distortion of PTEPA, which is consistent with the observed hierarchical pore structure. As a cathode material, PTEPA exhibits a discharge capacity of 89.5 mAh g-1 in the initial cycle with a highly sloping two-stage discharge curve and relatively stable cycling performance. Beyond its excellent energy storage properties, PTEPA also shows relatively good electrochromic performance. Furthermore, an efficient all-solid-state electrochromic supercapacitor (ECSC) with good electrochromic performance and high energy storage capacity (13.3 mF cm-2 ) is assembled from PTEPA and nanoporous graphene films. During charge-discharge processes, the color of the ECSC changes between yellow-green and steel blue. Thus, the energy storage level of the ECSC can be monitored by the corresponding color changes. The fabricated ECSC may have practical applications, for example, in self-powered electrochromic smart windows.

4.
Dalton Trans ; 2020 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-32242884

RESUMO

The coordination characteristics and donor/acceptor properties of a series of 2-pyridyl substituted phosphine ligands have been investigated using structural, spectroscopic and DFT calculational studies. A range of different coordination modes are observed in Mo and W carbonyl complexes of tris-2-pyridyl-phosphine ligands of the type P(2-py') (2-py' = substituted or unsubstituted 2-pyridyl group), including an unprecedented example exhibiting N,N',µ2-π coordination. DFT calculations were used to assess the relative donor/acceptor properties of a range of related 2-pyridyl-phosphine ligands with respect to PPh3 and PtBu3.

5.
Inorg Chem ; 2020 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-32330014

RESUMO

A series of new tris(2-pyridyl) bismuthine ligands of the type [Bi(2-py')3] have been prepared, containing a range of substituents at various positions within their pyridyl rings (py'). They can act as intact ligands or, as a result of the low C-Bi bond energy, exhibit noninnocent reactivity in the presence of metal ions. Structural studies of Li+ and Ag+ complexes show that the coordination to metal ions using their pyridyl-N atoms and to anions using the Lewis acidity of their Bi(III) centers can be modified by the presence of substituents within the 2-pyridyl rings, especially at the 6- or 3-positions, which can block the donor-N or Lewis acid Bi sites. Electron withdrawing groups (like CF3 or Br) can also severely reduce their ability to act as ligands to metal ions by reducing the electron donating ability of the pyridyl-N atoms. Noninnocent character is found in the reactions with Cu+ and Cu2+, resulting in the coupling of pyridyl groups to form bipyridines, with the rate of this reaction being dependent on the anion present in the metal salts. This leads to the formation of Bi(III)/Cu(I) complexes containing hypervalent [X2Bi(2-R-py)]- (X = Cl, Br) anions. Alternatively, the tris(2-pyridyl) bismuthine ligands can act as 2-pyridyl transfer reagents, transferring 2-py groups to Au(I) and Fe(II).

6.
Dalton Trans ; 49(11): 3403-3407, 2020 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-32129399

RESUMO

Coordination of Cu(i) or Pd(ii) to seleno-cyclodiphosph(v)azanes of the type [RNH(Se)P(µ-NtBu)]2 results in positively charged anion receptor units which have increased anion affinity over the neutral seleno-phosph(v)azanes, due to the increase in electrostatic interactions between the receptor and the guest anions. The same effect is produced by replacement of one of the P[double bond, length as m-dash]Se units by a P-Me+ unit.

7.
Artigo em Inglês | MEDLINE | ID: mdl-32057229

RESUMO

Multifunctional nanocoatings have been of central importance in various technological fields, yet their fabrication, especially on flexible substrates, still remains a persistent challenge to date. We herein demonstrate a mild single-step drop-and-dry approach to the in situ growth of hierarchical grass-like nanostructures on flexible cotton fabrics. A precursor solution comprising titanium-oxo clusters [Ti18MnO30(OEt)20(MnPhen)3] (Phen = 1,10-phenanthroline) and AgNO3 is employed wherein Ag+ cations are in situ-reduced to silver nanoparticles (AgNPs). Drop-casting onto cotton fabrics under mild conditions induces the in situ growth of the heterogeneous grass-like assembly, and each constituent nanofibrous 'grass leaf' incorporates AgNPs both on the surface and embedded in the interior. The hierarchical morphology and heterogeneous composition of these grass-like nanostructures impart the coated cotton fabrics with enhanced antibacterial properties, robust hydrophobicity, and UV-blocking capability, which are features desired in textile materials but lacking in natural cotton.

8.
Chem Commun (Camb) ; 56(6): 854-871, 2020 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-31859335

RESUMO

Complex metal oxides, defined as metal oxide materials with multiple metals, phases or including dopants, are used in a huge variety of modern applications ranging from photocatalysis, transparent conductive materials, supercapacitors and battery components. In this feature article, the use of mixed-metal single source precursors to synthesise complex metal oxides is explored. The structures and decomposition/reaction pathways of various precursors including mixed-metal alkoxides, complexes with chelating ligands, clusters, polyoxometallates, and metal-organic frameworks are discussed. The advantages and opportunities of using a single source precursor strategy are investigated and highlighted.

9.
J Am Chem Soc ; 142(2): 1029-1037, 2020 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-31877039

RESUMO

Anion binding by receptor molecules is a central field of modern chemistry which impacts areas of catalysis as well as biological and materials chemistry. As binding often requires high chemical stability under aerobic and aqueous conditions for practical applications, carbon-based anion receptors have dominated this field, with main group element analogues receiving far less attention. The recent observation that the air- and moisture-stable amino-cyclophosph(V)azanes of the type [RN(E)P(µ-NR)]2 (E = O, S, Se) can exhibit halide binding that is competitive with topologically related organic receptors (such as squaramides and thioureas) has motivated us here to explore how the binding properties of phosphazane receptors can be enhanced further. Coordination of transition metals by the two P,N metal coordination sites of the phosph(III)azane dimer [(2-py)NHP(µ-NtBu)]2 not only activates the receptor for anion binding (by fixing the optimum exo-exo conformation and polarizing the endocyclic N-H substituents) but also stabilizes the P2N2 ring to hydrolysis and oxidation. We show how the binding properties of these receptors can be modulated by the coordinated metal fragments and that they can bind chloride 1 to 2 orders of magnitude stronger than the related squaramides and thioureas. These features can be utilized in anion transport through phospholipid bilayers under aqueous conditions for which transport can be improved by 1 order of magnitude compared to the previous best phosphazane and thiourea transporters. This study demonstrates how careful design of inorganic systems can result in potent supramolecular functionality, beyond that observed for organic counterparts.

10.
Chemistry ; 25(61): 14003-14009, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31469199

RESUMO

The systematic assembly of supramolecular arrangements is a persistent challenge in modern coordination chemistry, especially where further aspects of complexity are concerned, as in the case of large molecular mixed-metal arrangements. One targeted approach to such heterometallic complexes is to engineer metal-based donor ligands of the correct geometry to build 3D arrangements upon coordination to other metals. This simple idea has, however, only rarely been applied to main group metal-based ligand systems. Here, we show that the new, bench-stable tris(3-pyridyl)stannane ligand PhSn(3-Py)3 (3-Py=3-pyridyl) provides simple access to a range of heterometallic SnIV /transition metal complexes, and that the presence of weakly coordinating counter anions can be used to build discrete molecular arrangements involving anion encapsulation. This work therefore provides a building strategy in this area, which parallels that of supramolecular transition metal chemistry.


Assuntos
Complexos de Coordenação/química , Metais/química , Polímeros/química , Compostos de Estanho/química , Cristalografia por Raios X , Ligantes , Conformação Molecular , Estanho/química
11.
Angew Chem Int Ed Engl ; 58(31): 10655-10659, 2019 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-31157489

RESUMO

Modern supramolecular chemistry is overwhelmingly based on non-covalent interactions involving organic architectures. However, the question of what happens when you depart from this area to the supramolecular chemistry of structures based on non-carbon frameworks remains largely unanswered, and is an area that potentially provides new directions in molecular activation, host-guest chemistry, and biomimetic chemistry. In this work, we explore the unusual host-guest chemistry of the pentameric macrocycle [{P(µ-Nt Bu}2 NH]5 with a range of anionic and neutral guests. The polar coordination site of this host promotes new modes of guest encapsulation via hydrogen bonding with the π systems of the unsaturated C≡C and C≡N bonds of acetylenes and nitriles as well as with the PCO- anion. Halide guests can be kinetically locked within the structure by oxidation of the phosphorus periphery by oxidation to PV . Our study underscores the future promise of p-block macrocyclic chemistry.

12.
J Am Chem Soc ; 141(22): 8807-8815, 2019 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-31079456

RESUMO

The binding and sensing of anions is an important cross-disciplinary field, which impacts broad areas such as biology, supramolecular chemistry and catalysis. To date, however, this area has been dominated by organic architectures which function as H-bonding, anion receptor molecules. Inorganic anion receptors have largely been based on Lewis acidic metals, with very few examples of H-bonding counterparts of organic systems having been systematically studied. This paper develops strategies for enhancing the anion binding properties of phosphazanes of the type [(RNH)(E)P(µ-N tBu)]2 (E = O, S, Se) which are bench-stable, H-bond receptors that can be regarded as inorganic analogues of squaramides (a key class of organic anion receptor). The distinct advantages of these inorganic receptors over organic counterparts is the ease by which their functionality and electronic character can be altered (by means of the R group, chalcogenide, or metal present). Se substitution at the P centers, the presence of electron-withdrawing R groups, and metal coordination to the soft donor centers can be used to modulate and enhance anion binding. The water stability and superior anion binding properties of the seleno-phosph(V)azanes give them applications as synthetic anion transporters through phospholipid layers.

13.
Dalton Trans ; 48(17): 5692-5697, 2019 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-30968911

RESUMO

Post-functionalisation of the aluminate anion [EtAl(6-R-2-py)3]- (6-R-2-py = 6-R-2-pyridyl, R = Me or Br) can be accomplished via nucleophilic addition of the pyridyl groups to the electrophilic C[double bond, length as m-dash]O group of aldehydes (RCH[double bond, length as m-dash]O) or by deprotonation of carboxylic acids (RCO2H). NMR spectroscopic and crystallographic studies show how 6-Me-2-py groups can detect chirality and reveal a new aspect of isomerism.

14.
Dalton Trans ; 48(14): 4555-4564, 2019 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-30869665

RESUMO

VO(OiPr)3 is a useful precursor for the synthesis of a range of metal-doped polyoxovanadate (POV) cage compounds, its reactions with hydrated metal salts providing a route to arrangements containing Bi and other main group metals, transition metals and lanthanides. The new POV compounds [Bi2(DMSO)6V12O33Br]2[M(DMSO)6] (2Br-M, M = CoII, NiII, CuII, ZnII) [Bi2(DMSO)6V12O33Cl]2[Ca(DMSO)x]·yDMSO (2Cl-Ca), [Bi2(DMSO)6V12O33Cl]2[LnCl(DMSO)7] (2Cl-Ln, Ln = LaIII, CeIII, EuIII), [Bi2(DMSO)6V10O28F2]3[Bi(DMSO)5]2 (3), [V12O32(DMSO)][Gd(NO3)(DMSO)5.5]2 (4) and [Ln(DMSO)4V12O32Cl][LnCl(DMSO)7] (5Cl-Ln, Ln = CeIII, EuIII) have been structurally characterised, and their properties studied using UV-Vis spectroscopy and cyclic voltammetry. Drop-casting these compounds onto fluorine-doped tin oxide followed by calcination provides a simple approach to thin films of metal-doped BiVO4 or LnVO4, depending on the composition of the cage precursor. The applications of the BiVO4 films as photoanodes for water oxidation is explored, with transition metal doping of BiVO4 improving the activity (∼1.8-2.4 times the photocurrent density of undoped BiVO4 at 1.23 V vs. RHE) while lanthanide or Ca-doping is detrimental.

15.
Chem Commun (Camb) ; 54(100): 14132-14135, 2018 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-30499991

RESUMO

Electropolymerisation of the novel polyoxotitanate (POT) hexamer [Ti(µ3-O)(OiPr)(TA)]6 (TA = thiophene-3-acetate) with 3,4-ethylenedioxythiophene (EDOT) gives films of hybrid conjugated copolymer, Poly-(EDOT-POT)s, the morphologies of which are, uniquely, influenced by the electropolymerisation potential. Nanoporous Poly-(EDOT-POT)-1 is a fast-ion electrode material and has improved electrochromic properties and significantly higher capacitance than that of the parent poly(3,4-ethylenedioxythiophene) (PEDOT).

16.
Adv Mater ; 30(46): e1804033, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30285284

RESUMO

Single-source precursors are used to produce nanostructured BiVO4 photoanodes for water oxidation in a straightforward and scalable drop-casting synthetic process. Polyoxometallate precursors, which contain both Bi and V, are produced in a one-step reaction from commercially available starting materials. Simple annealing of the molecular precursor produces nanocrystalline BiVO4 films. The precursor can be designed to incorporate a third metal (Co, Ni, Cu, or Zn), enabling the direct formation of doped BiVO4 films. In particular, the Co- and Zn-doped photoanodes show promise for photoelectrochemical water oxidation, with photocurrent densities >1 mA cm-2 at 1.23 V vs reversible hydrogen electrode (RHE). Using this simple synthetic process, a 300 cm2 Co-BiVO4 photoanode is produced, which generates a photocurrent of up to 67 mA at 1.23 V vs RHE and demonstrates the scalability of this approach.

17.
Chem Commun (Camb) ; 54(86): 12271, 2018 11 07.
Artigo em Inglês | MEDLINE | ID: mdl-30325367

RESUMO

Correction for 'Synthesis of Ca(PF6)2, formed via nitrosonium oxidation of calcium' by Evan N. Keyzer et al., Chem. Commun., 2017, 53, 4573-4576.

18.
Chemistry ; 24(64): 17019-17026, 2018 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-30092123

RESUMO

Postfunctionalization of the aluminate anion [EtAl(6-Me-2-py)3 ]- (1) (2-py=2-pyridyl) with alkoxide ligands can be achieved by the selective reactions of the lithium salt 1 Li with alcohols in the appropriate stoichiometry. This method can be used to introduce 3- and 4-py functionality in the form of 3- and 4-alkoxymethylpyridyl groups, while maintaining the integrity of the aluminate framework, thereby giving entry to new supramolecular chemistry. Chirality can be introduced either by using a chiral alcohol as a reactant or by the stepwise reaction of 1 Li with two different nonchiral alcohols. The latter route has allowed the synthesis of a rare example of a chiral-at-aluminium aluminate.

19.
Dalton Trans ; 47(20): 7036-7043, 2018 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-29741181

RESUMO

Difficulties in the preparation of neutral ligands of the type [RSi(2-py)3] (where 2-py is an unfunctionalised 2-pyridyl ring unit) have thwarted efforts to expand the coordination chemistry of ligands of this type. However, simply switching the pyridyl substituents to 6-methyl-pyridyl groups (6-Me-2-py) in the current paper has allowed smooth, high-yielding access to the [PhSi(6-Me-2-py)3] ligand (1), and the first exploration of its coordination chemistry with transition metals. The synthesis, single-crystal X-ray structures and solution dynamics of the new complexes [{PhSi(6-Me-2-py)3}CuCH3CN][PF6], [{PhSi(6-Me-2-py)3}CuCH3CN][CuCl2], [{PhSi(6-Me-2-py)3}FeCl2], [{PhSi(6-Me-2-py)3}Mo(CO)3] and [{PhSi(6-Me-2-py)3}CoCl2] are reported. The paramagnetic Fe2+ and Co2+ complexes show strongly shifted NMR resonances for the coordinated pyridyl units due to large Fermi-contact shifts. However, magnetic anisotropy also leads to considerable pseudo-contact shifts so that both contributions have to be included in the paramagnetic NMR analysis.

20.
Dalton Trans ; 47(19): 6675-6678, 2018 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-29693678

RESUMO

Main group inorganic macrocycles, based on p-block element backbones other than carbon, are a challenging synthetic target that has been largely overlooked. In this study, we show that a simple strategy based on the combination of electrophilic and nucleophilic phosphazane building blocks can be extended to readily accessible [E(tBuN)P(µ-NtBu)]22- nucleophilic components, as exemplified by the Se-bridge PIII/PV phosphazane macrocycle [{(tBuN[double bond, length as m-dash])PV(µ-NtBu)}2(µ-Se)2{PIII(µ-NtBu)}2]3.

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