Search

Transistor performance is a key enabler for state-of-theart electronic devices. Besides fast switching performance, low power consumption is a critical parameter for mobile products. The implementation of HfO2 as a gate dielectric with a high permittivity reduces leakage current and power consumption drastically. Metal gates and work function materials are required to adjust Fermi levels and are essential for device performance. In addition to these key elements of high-k metal gate (HKMG) technology, encapsulation liners and spacers are found to have a significant impact. We show that the performance of HKMG transistors has a strong dependency on the film quality and growth conditions of the SiN spacers. A good conformality and excellent step coverage at low deposition temperature is achieved with an atomic layer deposition (ALD) process using dichlorosilane and ionized radicals of ammonia. This ALD process is superior to standard LPCVD and PECVD processes with regards to thickness control, within-wafer-uniformity and matching of the thickness values between dense and isolated transistors. ALD SiN is applied as a spacer to define the implant profiles. The impact of the ALD SiN spacers on transistor universal curve, miller capacitance and Vt is demonstrated. Further application is a hard mask for selective epitaxy of SiGe.

4,4′-biphenylene spaced lipophilic bis-β-diketone ligands of the type 4,4′-bis(RC(O)CH2C(O))C12H8 (R = Pr, Ph, hexyl, octyl, nonyl) have been prepared and used for the liquid–liquid extraction of d-block metal ions. These ligands are expected to interact with divalent metal ions to form charge-neutral trinuclear metallocycles of type [M3(L3)3(solvent)] as has been demonstrated with the previously reported derivative of H2L3 (R = tBu), the X-ray structure of which is reported. Liquid–liquid extraction studies were performed in a two-phase water/chloroform system employing a radiotracer technique for cobalt(II) and zinc(II). These experiments involved the systematic variation of ligand, metal and 4-ethylpyridine concentrations to probe the stoichiometries of the species extracted. Synergistic extraction was observed when 4-ethylpyridine was present with the ligand in the organic phase. Competitive extraction studies demonstrated the ligands are highly selective for copper(II) over cobalt(II), nickel(II), zinc(II) and cadmium(II).

Interaction of copper(II) salts with 2,2′-dipyridylamine (1), N-cyclohexylmethyl-2,2′-dipyridylamine (2), di-2-pyridylaminomethylbenzene (3), 1,2-bis(di-2-pyridylaminomethyl)-benzene (4), 1,3-bis(di-2-pyridylaminomethyl)benzene (5), 1,4-bis(di-2-pyridylaminomethyl)benzene (6), 1,3,5-tris(di-2-pyridylaminomethyl)benzene (7) and 1,2,4,5-tetrakis(di-2-pyridylaminomethyl)benzene (8) has yielded the following complexes: [Cu(2)(μ-Cl)Cl]2, [Cu(3)(μ-Cl)Cl]2 · H2O, [Cu2(4)(NO3)4], [Cu2(5)(NO3)4] · 2CH3OH, [Cu2(6)(CH3OH)2(NO3)4], [Cu4(8)](NO3)4] · 4H2O while complexation of palladium(II) with 1, 4, 5 and 6 gave [Pd(1)2](PF6)2 · 2CH3OH, [Pd2(4)Cl4], [Pd2(4)(OAc)4], [Pd2(5)Cl4], [Pd2(6)Cl4] and [Pd2(6)(OAc)4] · CH2Cl2, respectively. X-ray structures of [Cu(2)(μ-Cl)Cl]2, [Cu(3)(μ-Cl)Cl]2 · 2C2H5OH, [Cu2(6)(CH3OH)2(NO3)4], [Pd(1)2](PF6)2 · 2CH3OH, [Pd2(4)(OAc)4] · 4H2O and [Pd2(6)(OAc)4] · 2CH2Cl2 are reported. In part, the inherent flexibility of the respective ligands has resulted in the adoption of a diverse range of coordination geometries and lattice arrangements, with the structures of [Pd2(4)(OAc)4] · 4H2O and [Pd2(6)(OAc)4] · 2CH2Cl2, incorporating the isomeric ligands 4 and 6, showing some common features. Liquid–liquid (H2O/CHCl3) extraction experiments involving copper(II) and 1–3, 5, 7and 8 show that the degree of extraction depends markedly on the number of dpa-subunits (and concomitant lipophilicity) of the ligand employed with the tetrakis-dpa derivative 8 acting as the most efficient extractant of the six ligand systems investigated.

Three copper(II) complexes derived from 2-(hydroxymethyl)pyridine (LH) have been synthesised and a comparative X-ray investigation of their respective crystal structures undertaken. In the absence of added base, LH reacts with copper(II) chloride or nitrate to yield the five-coordinate [Cu(LH)2Cl]Cl and six-coordinate [Cu(LH)2(NO3)2] species. In the chloro complex the coordination geometry is distorted trigonal bipyramidal, with the pyridyl nitrogens occupying the axial position and two hydroxyl oxygens from the bidentate ligands together with a chloro group occupying the equatorial sites. The structure of the nitrate species, published previously, has been reinvestigated at low temperature in order to specify the weak interactions in the crystal; it contains two molecules of bidentate LH bound trans in the equatorial plane while monodentate nitrato ligands occupy the axial sites. In each of these complexes the hydroxyl protons act as hydrogen bond donors, interacting with the non-coordinated chloride anion in [Cu(LH)2Cl]Cl and the coordinated nitrato groups in [Cu(LH)2(NO3)2] to form bridged, hydrogen-bonded, copper(II)-organic arrays in each case; offset face-to-face π-stacking in the latter produces a two dimensional structure. Further weak CH⋯Cl, CH⋯O interactions stabilise both arrangements. The X-ray structure of the complex [Cu(L)2] · 4H2O containing the deprotonated ligand is also described. The presence of the latter results in the above hydrogen bonding arrangements being ‘switched off’ and instead a new two-dimensional network involving bridging tetrameric water clusters hydrogen bound to adjacent ligand hydroxo groups to give extended sheets is generated; offset face-to-face π-stacking occurs between sheets to yield a three dimensional array.

In the discussion that follows some of the more recent progress in the area of anion binding by synthetic polyamine receptors is presented, with emphasis given to work undertaken by the authors’ groups. A continuing theme in these studies has been the relationship between receptor structure and its anion extraction properties. Systematic solvent extraction and structural studies for halide and perrhenate complexes with polyamines of tripodal, macrocyclic and macrobicyclic architecture that contain both aromatic moieties and four to eight amine functions have been performed in order to derive relevant structure-binding/extractability relationships. The results demonstrate that the binding and extraction behaviour of the polyamines towards halides and perrhenate is a complex function of their structural features, degree of protonation and lipophilic properties. The extraction is characterized by the preferred formation of mono- and diprotonated amine species in the organic phase. X-ray structure studies of iodide and perrhenate complexes with open-chain tetraamino derivatives and octaamino cryptands in different protonation states lead to the conclusion that in the first case only limited chelation of the anion occurs and in the second only highly protonated species are able to encapsulate the anion. The structural patterns observed are strongly influenced by the presence of water molecules in the crystals.

Synthesis of the 2,2'-dipyridylamine derivatives di-2-pyridylaminomethylbenzene 1, 1,2-bis(di-2-pyridylaminomethyl)benzene 2, 1,3-bis(di-2-pyridylaminomethyl)benzene 3, 2,6-bis(di-2-pyridylaminomethyl)pyridine 4, 1,4-bis(di-2-pyridylaminomethyl)benzene 5, and 1,3,5-tris(di-2-pyridylaminomethyl)benzene 6 are reported together with the single-crystal X-ray structures of 2, 3, and 5. Reaction of individual salts of the type AgX (where X = NO(3)(-), PF(6)(-), ClO(4)(-), or BF(4)(-)) with the above ligands has led to the isolation of thirteen Ag(I) complexes, nine of which have also been characterised by X-ray diffraction. In part, the inherent flexibility of the respective ligands has resulted in the adoption of a range of coordination arrangements. A series of liquid-liquid (H(2)O/CHCl(3)) extraction experiments of Ag(I) with varying concentrations of 1-6 in the organic phase have been undertaken, with the counter ion in the aqueous phase being respectively picrate, perchlorate and nitrate. In general, extraction efficiencies for a given ionophore followed the Hofmeister order of picrateperchloratenitrate; in each case the tris-dpa derivative 6 acting as the most efficient extractant of the six systems investigated. Competitive seven-metal bulk membrane transport experiments (H(2)O/CHCl(3)/H(2)O) employing the above ligands as the ionophore in the organic phase and equimolar concentrations of Co(II), Ni(II), Zn(II), Cu(II), Cd(II), Pb(II) and Ag(I) in the aqueous source phase were also undertaken, with transport occurring against a pH gradient. Under the conditions employed 1 and 5 yielded negligible transport of any of the metals present in the source phase while sole transport selectivity for Ag(I) was observed for 2-4 and 6.

A series of pendant arm aza-thioether macrocycles containing hydrogen-bonding amide functionalities have been synthesised and the single crystal X-ray structures of [12]aneS3N–CONHCOPh, [12]aneS3N–CSNHCOPh, [12]aneS2ON–CONHCOPh, [12]aneS2ON–CH2CONHCONH–tBu, [15]aneS2ON2–(CH2CONHCONH–tBu)2 and [15]aneS3N2–(CH2CONHPh)2 are presented. The structural results confirm that the majority of the macrocyclic C–S linkages adopt gauche conformations with all sulfur atoms being exo-orientated with respect to the macrocyclic ring, while the oxygen atoms, when present, are endo-orientated. The pendant arms, formed by reaction of the parent macrocycle with acyl isocyanates, are twisted from co-planarity and typically form a distorted U-shape with angles between planes formed around the carbonyl units varying from 50.81° to 68.05°. The dominant motif in these structures involves dimeric units linked through hydrogen-bonds: however, such a network is disrupted in [12]aneS3N–CSNHCOPh by the substitution of a carbonyl unit for a thiocarbonyl unit. When more than one amide unit is present in the pendant arm, intramolecular hydrogen-bond networks are observed resulting in coplanar pendant arms and highly directional hydrogen-bonding. Inclusion of a methylene linker between the macrocycle and carbonyl function in the pendant arm inhibits intermolecular hydrogen-bond formation resulting in interaction of the amide proton with the macrocyclic nitrogen centres. A single crystal X-ray structure of [Ag([12]aneS3N–CH2CONH–tBu)(NO3)] confirms binding of Ag(I) to the macrocyclic moiety with additional hydrogen-bonding [N–H⋯O 2.901(3) A] between the macrocyclic pendant arm amide unit and the nitrate anion demonstrating that in the solid-state these ligands can act as heteroditopic receptors for metal salts. Overall, the solid-state structure of this complex is a one-dimensional polymer in which the Ag(I) cation is in a distorted square-pyramidal geometry with the apical sulfur donor emanating from an adjacent macrocyclic molecule. The efficacy of these ligands in competitive membrane transport and liquid–liquid metal ion extraction of Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Ag(I) and Pb(II) has been assessed using selected ligands. In preliminary experiments, clear extraction and transport selectivity for Ag(I) was observed in all systems investigated, while only modest extraction of TcO4− was identified.

The novel supramolecular assembly of composition [{(bz3tren)H4}4+ · (ReO4)— · 3(Cl)—] resulted from the self-organization of a mixture of tris[2-(benzylamino)ethyl]amine (bz3tren), HCl and NH4ReO4 at a molar ratio of 1:4.7:1 in methanol. The crystal architecture is characterized by stacks of repeating sandwich-type building blocks that contain charge-assisted N—H···O(Re) hydrogen bonds [N···O 2.81-2.86A] and weaker C—H···O(Re) interactions [C···O 3.11A]. The stacks are further linked by N—H···Cl [N···Cl 3.03A] and weaker C—H···Cl [C···Cl 3.47-3.74A] interactions into two-dimensional layers bordered by the benzyl groups of the [(bz3tren)H4]4+ cations. Edge-to-face C—H···π interactions involving the aromatic rings occur within and between the layers. The protonation constants of bz3tren in methanol were determined by potentiometric titration. The corresponding structures of the ligand in its different protonation states were calculated at the DFT-level. Anionen-gesteuerte supramolekulare Selbstorganisation von vierfach protoniertem Tris[2-(benzylamino)ethyl]amin Eine neue supramolekulare Verbindung der Zusammensetzung [{(bz3tren)H4}4+ · (ReO4)— · 3(Cl)—] wurde durch Selbstorganisation einer Mischung von Tris[2-(benzylamino)ethyl]amin (bz3tren), HCl und NH4ReO4 im Molverhaltnis 1:4.7:1 in Methanol erhalten. Ihre Kristallstruktur ist durch Stapel sandwichartiger Baueinheiten charakterisiert, die auf ladungsunterstutzten N—H···O(Re)-Wasserstoffbruckenbindungen [N···O 2.81—2.86A] und schwacheren C—H···O(Re)-Wechselwirkungen [C···O 3.11A] beruhen. Diese Stapel sind uber ein ausgepragtes zweidimensionales Wasserstoffbruckennetzwerk unter Nutzung von N—H···Cl-[N···Cl 3.03A] und schwacheren C—H···Cl-Bindungen [C···Cl 3.47—3.74A] verknupft. Zusatzliche C—H···π-Wechselwirkungen zwischen den endstandigen Benzylgruppen des Kations [(bz3tren)H4]4+ fuhren schlieslich zu einer dreidimensionalen Struktur. Die Protonierungskonstanten von bz3tren wurden in Methanol durch potentiometrische Titration bestimmt; Strukturanderungen des Liganden wurden in Abhangigkeit von der Protonierung durch DFT-Rechnungen ermittelt.

The interaction of silver(I) nitrate with the polypyridyl ligand (L) formed from two dipyridylamine units joined at their secondary amines by a 2,6-lutidinyl bridge results in a molecular ladder motif that consists of pairs of cationic [Ag2(L)MeCN]2+ units bridged by an unprecedented [Ag2(NO3)6]4− anion.

The interaction of Cu(II) with the following secondary N-substituted derivatives of di(2-picolyl)amine () are reported: N-cyclohexylmethyl-di(2-picolyl)amine (), N-benzyl-di(2-picolyl)amine (), N-(4-pyridylmethyl)-di(2-picolyl)amine (), N-(4-carboxymethylbenzyl)-di(2-picolyl)amine (), N-(9-anthracen-8-ylmethyl)-di(2-picolyl)amine (), 1,3-bis[di(2-picolyl)aminomethyl]benzene (), 1,4-bis[di(2-picolyl)aminomethyl]benzene () and 2,4,6-tris[di(2-picolyl)amino]triazine (). The solid complexes [Cu()(micro-Cl)](2)(PF(6))(2), [Cu()(micro-Cl)](2)(PF(6))(2).0.5CH(2)Cl(2), Cu()(ClO(4))(2), Cu()(2)(ClO(4))(2), [Cu()(ClO(4))(2)(H(2)O)].0.5H(2)O, Cu(2)()(ClO(4))(4), [Cu(2)()(Cl)(4)] and [Cu(2)(+H)(micro-OCH(3))(2)(H(2)O)](ClO(4))(3).C(4)H(10)O were isolated and X-ray structures of [Cu()(micro-Cl)](2)(PF(6))(2), [Cu()(micro-Cl)](2)(PF(6))(2).0.5CH(2)Cl(2,) [Cu()(2)(ClO(4))(2)(H(2)O)].0.5H(2)O, [Cu(2)()Cl(4)] and [Cu(2)(+H)(micro-OCH(3))(2)(H(2)O)](ClO(4))(3).C(4)H(10)O were obtained. The series is characterised by a varied range of coordination geometries and lattice architectures which in the case of [Cu()(ClO(4))(2)(H(2)O)].0.5H(2)O includes a chain-like structure formed by unusual intermolecular pi-interactions between metal bound perchlorate anions and the aromatic rings of adjacent anthracenyl groups. Variable temperature magnetic susceptibility measurements have been performed for [Cu()(micro-Cl)](2)(PF(6))(2) and [Cu()(micro-Cl)](2)(PF(6))(2).0.5H(2)O over the range 2-300 K. Both compounds show Curie-Weiss behaviour, with the data indicating weak antiferromagnetic interaction between the pairs of copper ions in each complex. Liquid-liquid (H(2)O/CHCl(3)) extraction experiments involving and as extractants showed that, relative to the parent (unsubstituted) dipic ligand , substitution at the secondary amine site in each case resulted in an increase in extraction efficiency towards Cu(II) (as its perchlorate salt); at least in part, this increase may be attributed to the enhanced lipophilicities of the N-substituted derivatives.

A new metallo-capsule has been synthesised that consists of three copper(II) ions and two molecules of a tris-deprotonated tripodal ligand in which three 2,4-pentanedione groups are linked via their gamma-carbons through thioether spacers to the 1,3,5-positions of a triazine core.

A trinuclear metallo-capsule has been assembled from a new tripodal pyridyl ligand and three silver(I) ions; the X-ray structure shows the presence of a Ag-Ag interaction in the solid state giving rise to a non-symmetric capsule arrangement while NMR evidence indicates that the structure in solution is symmetrical.