One-dimensional coordination polymers based on first-row transition metals: a solid-state study of weak backbone interactions

Journal ArticleWe present further data on the solid-state structures of one-dimensional coordination polymers based upon dipositive transition metal hexafluoroacetylacetonate (hfacac) complexes. A variety of linking subunits are employed in order to investigate and probe the relatively weak interactions that make up the backbones of these polymers. Reported in this study are metal complexes containing manganese, zinc, copper, and cobalt and a range of donor building blocks encompassing an array of bonding motifs, including pyridyl-metal, pyridyl(N-oxide)-metal, and hydrogen bonding. The specific linkers utilized are 4,4′-dipyridyl N,N′- dioxide hydrate, 2,5-bis(4-ethynylpyridyl)furan, 4,4′-trimethylenedipyridine, and trans-1-(2-pyridyl)-2-(4-pyridyl)-ethylene. A detailed discussion of the products is presented, as is a comparison to known compounds of a similar nature. All compounds are characterized via single-crystal X-ray diffraction and elemental analysis for the bulk of the sample

Copper deposition on TiO2 from copper(II)hexafluoroacetylacetonate

The authors have studied the adsorption of CuII(hfac)2 on the surface of a model oxide system, TiO2(110), and probed the molecular stability with respect to thermal cycling, using atomic scale imaging by scanning tunneling microscopy supported by x-ray photoemission spectroscopy. They find that at 473 K, the adsorbed metal-organic molecules begin to dissociate and release Cu atoms which aggregate and form Cu nanoparticles. These Cu nanoparticles ripen over time and the size (height) distribution develops into a bimodal distribution. Unlike other organometallic systems, which show a bimodal distribution due to enhanced nucleation or growth at surface step edges, the nanoparticles do not preferentially form at steps. The reduced mobility of the Cu islands may be related to the co-adsorbed ligands that remain in very small clusters on the surface

Vapour-Phase Deposition of Functional Nanolayers

Vapour-phase deposition techniques have many advantages including being solventless and providing fine control (down to the nanometre level) of coating thickness. This thesis is about the use of both plasmachemical deposition and oxidative vapour-phase deposition to form functional coatings. Chapter 1 provides brief reviews of proton exchange membrane fuel cells and vapour-phase deposition techniques as well as an overall introduction to the thesis. Chapter 2 is a synopsis of the most commonly used experimental techniques used throughout this thesis (especial attention is focused on XPS and FTIR as they are used in every chapter). Chapters 3–4 record the use of plasmachemical deposition to form proton-conducting coatings for potential use in fuel cells. The strategy described is the use of anhydride precursors in order to produce layers with a high density of carboxylic acids. In chapter 4 these layers themselves are used as initiators to graft sulfonic-acid containing polymer brushes for the enhancement of proton conductivity. Chapter 5 describes the fabrication of poly(ionic liquid) layers by depositing an imidazole-containing precursor via pulsed plasmachemical deposition, which is subsequently quaternized via a vapour-phase reaction with 1-bromobutane. The resultant coatings show high values of ionic conductivity above 90 ◦C. In chapter 6 plasma enhanced chemical vapour deposition of metal(II) hexafluoroacetylacetonate precursors is used in order to produce metal-containing nanocomposite layers. The retention of an organic matrix and its chemical rearrangement under plasma conditions leads to high ionic conductivities. Chapters 7–8 utilize an atomized spray delivery system and plasma in conjunction with liquid precursor mixtures in order to form bioactive coatings (chapter 7) and nanocomposite layers (chapter 8) which show good adhesion and lithium-ion conductivity values. Finally chapter 9 utilizes the atomized spray system to deliver high vapour pressures of 3,4-ethylenedioxythiophene in the presence of triflic anhydride which acts as an oxidant. The ensuing vapour-phase reaction yields a conducting polymer coating

SURFACE SCIENCE APPROACH TO ATOMIC LAYER DEPOSITION CHEMISTRY

Recently, atomic layer deposition (ALD) has been employed as a promising technique for the growth of solid thin films with high conformality on complex geometries such as heterogeneous catalysts and microelectronic devices. In this work, surface sensitive characterization techniques have been employed to investigate initial precursor-substrate reactions and ALD surface chemistry

Hollow Microcrystals of Copper Hexafluoroacetylacetonate-Pyridine Derivative Adducts via Supercritical CO2 Recrystallization

An innovative crystallization process, based in the use of the eco-friendly supercritical carbon dioxide (scCO2) solvent, is presented for the production of coordination compounds macrocrystals of general formula [Cu(hfacac)2(dPy)2], with intriguing prismatic hollow structures and single polymorphic forms. On the contrary, conventional solvents yielded compact microstructures. Studied pyridine derivatives (dPy) were 4-phenylpyridine, PhPy; 4-benzylylpyridine, BzPy; and 4-acetylpyridine, AcPy. In the specific case of the [Cu(hfacac)2(AcPy)2] adduct, the use of scCO2 as a solvent allows obtaining a pure polymorph, while the conventional solvent trials yielded a mixture of two polymorphs. Four new crystalline structures have been resolved from single crystal X-ray diffraction. All the structures consist in mononuclear complexes connected through intermolecular interactions, including H···H, H···O, F···F, C-F···Caromatic and/or C-F··· interactions, generating bidimensional networks that determine their crystallization mode in scCO2.This work was partially financed by the Spanish National Plan of Research CTQ2014-56324 and Severo Ochoa SEV-2015-0496, and by the Generalitat de Catalunya 2014SGR377. A. López-Periago acknowledges the RyC-2012-11588 contract. ALBA synchrotron is acknowledged for the provision of beamtime.Peer Reviewe

A novel copper precursor for electron beam induced deposition

A fluorine free copper precursor, Cu(tbaoac)2 with the chemical sum formula CuC16O6H26 is introduced for focused electron beam induced deposition (FEBID). FEBID with 15 keV and 7 nA results in deposits with an atomic composition of Cu:O:C of approximately 1:1:2. Transmission electron microscopy proved that pure copper nanocrystals with sizes of up to around 15 nm were dispersed inside the carbonaceous matrix. Raman investigations revealed a high degree of amorphization of the carbonaceous matrix and showed hints for partial copper oxidation taking place selectively on the surfaces of the deposits. Optical transmission/reflection measurements of deposited pads showed a dielectric behavior of the material in the optical spectral range. The general behavior of the permittivity could be described by applying the Maxwell–Garnett mixing model to amorphous carbon and copper. The dielectric function measured from deposited pads was used to simulate the optical response of tip arrays fabricated out of the same precursor and showed good agreement with measurements. This paves the way for future plasmonic applications with copper-FEBID

Formation Of Pure Cu Nanocrystals Upon Post-growth Annealing Of Cu-c Material Obtained From Focused Electron Beam Induced Deposition: Comparison Of Different Methods

In this paper we study in detail the post-growth annealing of a copper-containing material deposited with focused electron beam induced deposition (FEBID). The organometallic precursor Cu(II)(hfac)(2) was used for deposition and the results were compared to that of compared to earlier experiments with (hfac) Cu(I)(VTMS) and (hfac) Cu(I)(DMB). Transmission electron microscopy revealed the deposition of amorphous material from Cu(II)(hfac)(2). In contrast, as-deposited material from (hfac) Cu(I)(VTMS) and (hfac) Cu(I)(DMB) was nano-composite with Cu nanocrystals dispersed in a carbonaceous matrix. After annealing at around 150-200 degrees C all deposits showed the formation of pure Cu nanocrystals at the outer surface of the initial deposit due to the migration of Cu atoms from the carbonaceous matrix containing the elements carbon, oxygen, and fluorine. Post-irradiation of deposits with 200 keV electrons in a transmission electron microscope favored the formation of Cu nanocrystals within the carbonaceous matrix of freestanding rods and suppressed the formation on their surface. Electrical four-point measurements on FEBID lines from Cu(hfac)(2) showed five orders of magnitude improvement in conductivity when being annealed conventionally and by laser-induced heating in the scanning electron microscope chamber.615081517COST Action [CM1301]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)State University of Campinas (UNICAMP

Impregnation of Materials in Supercritical CO₂ to Impart Various Functionalities

Supercritical CO2 (scCO2) impregnation has attracted growing interest due to its unique properties such as high diffusivity, low surface tension, and ease of solvent removal at the end of the process. In addition, scCO2 is the most environmentally acceptable solvent possessing many advantages compared with the conventional aqueous and solvent-based processing. scCO2 impregnation has a wide range of applications mainly used to incorporate various active principles such as pharmaceuticals, functional finishing agents, colorants, and other agents into a polymeric matrix. This chapter reviews some studies carried out so far about the application of scCO2 as impregnation medium to develop various functional materials and it is intended to stimulate further research into the application of scCO2 to textile functionalization. It mainly focuses on applications related to textiles and some polymeric films

Bis(μ-4-phenyl­pyridine N-oxide-κ2 O:O)bis­[bis­(1,1,1,5,5,5-hexa­fluoro­pentane-2,4-dionato)copper(II)]

The asymmetric unit of the title compound, [Cu2(C5HF6O2)4(C11H9NO)2], contains one half of the centrosymmetric dinuclear complex. The coordination geometry of the CuII atom is octa­hedral, exhibiting a typical Jahn–Teller distortion. One trifluoro­methyl group is rotationally disordered between two orientations in a 1:1 ratio