Sulfur Nitride Research Articles

Dissociation Without Detonation: A DFT Analysis of the Thermally Induced Fragmentation of Binary Sulfur-Nitrogen Rings and Cages.

Potential thermal dissociation pathways available to binary sulfur nitrides have been explored by density functional theory methods, and the results interpreted in terms of their known thermochemical behavior. The cyclic cation/anion pair S3N3± both undergo concerted (4 + 2) cycloreversions to afford the 3-membered thiadiazirine ring c-NSN and, respectively, the SNS± cation/anions. A similar pathway has been identified for S4N2, leading to S3 and c-NSN. More complex multistep routes for the elimination of c-NSN have been identified for the bicyclic cation/anion pair S4N5±, as well as for the neutral cage structures S4N4 and S5N6. For the S4N5+ cation a transition state for competing skeletal scrambling via a 1,3-nitrogen σ-bond shift has been located. For the multiply charged cations S3N22+ and S4N42+, dissociation mechanisms are driven by charge repulsion effects, affording SNS+/SN+ and S3N3+/SN+ respectively. Channels leading to loss of NS+ from the cyclic cation species S4N3+ and S5N5+ have also been examined, and the possible role of open-chain and cyclic S3N2-based intermediates in the formation of S2N2 during the thermal cracking of S4N4 over silver wool is explored.

1-Ethyl-3-methylimidazolium Acetate as a Reactive Solvent for Elemental Sulfur and Poly(sulfur nitride).

We investigate the reactive dissolution process of poly(sulfur nitride) (SN)x in the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate [EMIm][OAc] in comparison to the process of elemental sulfur in the same IL. It has been known from the literature that during the reaction of S8 with [EMIm][OAc], the respective thione is formed via a radical mechanism. Here, we present new results on the kinetics of the formation of the respective imidazole thione (EMImS) via the hexasulfur dianion [S6]2- and the trisulfur radical anion [S3]•-. We can show that [S6]2- is formed first, which dissociates then to [S3]•-. Also, long-term stable radicals occur, which are necessary side products provided in a reaction scheme. During the reaction of [EMIm][OAc] with (SN)x chains, two further products can be identified, one of which is the corresponding imine. The reactions are followed by time-resolved NMR spectroscopic methods that showed the corresponding product distributions and allowed the assignment of the individual signals. In addition, continuous-wave (CW) EPR and UV/vis spectroscopic measurements show the course of the reactions. Another significant difference in both reactions is the formation of a long-term stable radical in the sulfur-IL system, which remains active over 35 days, while for the (SN)x-IL system, we can determine a radical species only with the spin trap 5,5-dimethyl-1-pyrrolin-N-oxide, which indicates the existence of short-living radicals. Since the molecular dynamics are restricted based on the EPR spectra, these radicals must be large.

Inorganic polymers as drug carriers: opportunities and challenges

Innovative methods and significant developments in designing new synthetic inorganic materials have been used to overcome limitations of current drug delivery systems. Inorganic polymers are widely used in the field of biomedicine, imaging, tissue engineering and drug delivery because of their bioactivity, biocompatibility, and stability. A few of the more well-known wholly inorganic polymers are portland cement, silicon dioxide, polyanionic glasses (including titania- and aluminosilicate glasses), poly(sulphur nitride), polycrystalline diamond, graphite, poly(sulphur nitride), and alumi¬num-silicate materials. Inorganic polymers, especially those possessing significant porosity, are good potential candi¬dates for the delivery of several drugs (anticancer, antibiotics, and anti-inflammatories), providing advantages such as encapsulation, controlled delivery, and improved targeting of drugs. Choosing a suitable drug carrier with a selec¬tive targeting potential also seems to be a very promising way for improving stability as well as selectivity. Despite all the advances, developing homogeneous inorganic polymers with narrow molecular weight distributions is a multidis¬ciplinary challenge. The current keynote speech provides a review of the opportunities and challenges of using inor¬ganic polymers as drug carriers.

Synthesis and Characterization of 15N‐Labeled Poly(sulfur nitride) in Bulk and in Superconductor Composites

Abstract15N‐labeled tetrasulfur tetranitride (S415N4) was synthesized by reacting S2Cl2 with 15NH3. The reaction was finalized with 14NH3. The successful labeling was confirmed by solution 15N nuclear magnetic resonance (NMR) spectroscopy. S415N4 was used for the synthesis of poly(sulfur nitride) S15Nx via the intermediate species of S2N2. It was a topochemical polymerization in the solid state. The isotope ratio in the labeled polymer was obtained by laser deposition ionization time‐of‐flight mass spectroscopy. Solid‐state 15N NMR spectroscopy of S15Nx indicates that at least three different chemical environments for 15N atoms are present in the crystals. Finally, SNx was polymerized in the presence of two other superconductors, MgB2 and yttrium barium copper oxide (YBCO), which demonstrates the capability of SNx for grain boundary engineering.

Editorial

Editorial

Alan Graham MacDiarmid. 14 April 1927—7 February 2007

Alan G. M ac Diarmid was an inorganic chemist by training who pioneered the field of synthetic metals. He grew up in a family that lived frugally, and he had to work in the Chemistry Department of the Victoria University of Wellington as a laboratory assistant before he could undertake part-time degree studies. He was awarded a Fulbright Scholarship to the University of Wisconsin, where he completed his first PhD with Norris Hall. The desire to receive a higher degree in the UK led to a Shell Scholarship to complete a second doctorate with Harry Emeléus FRS. After a sojourn at the University of St Andrews, Alan M ac Diarmid was appointed to an academic position at the University of Pennsylvania, where he remained essentially for his whole career. His early research was based on the properties of silicon hydrides, but he also became interested in poly(sulfur nitride). This led to a search in collaboration with Alan J. Heeger for intrinsically conducting non-metallic materials. A chance meeting with Hideki Shirakawa at the University of Tokyo led to M ac Diarmid being shown thin metallic-like films of poly(acetylene) made in Shirakawa's laboratory. Shirakawa travelled to Philadelphia to collaborate with M ac Diarmid and Heeger on the halogen ‘doping’ of poly(acetylene), which led to the discovery that the doped material was an excellent conductor. Thus, the field of synthetic metals was born. This paradigm-shifting work in which a polymer was shown to be a conductor led to the award of the 2000 Nobel Prize in Chemistry to these three individuals. M ac Diarmid went on to study in great detail the properties of polyaniline; the fact that it could be processed from solution and further modified by oxidative and protonic doping led to all sorts of potentially interesting opportunities in optoelectronics. From all this research, the modern field of organic electronic materials emerged as an important disruptive technology whose advancement depended on an entirely new branch of interdisciplinary science.

New alkaline-earth amidosulfates and their unexpected decomposition to S4N4.

The amidosulphates Mg(NH2SO3)2·4H2O (P21/c), Mg(NH2SO3)2·3H2O (P1̄), Ca(NH2SO3)2·4H2O (C2/c), Ca(NH2SO3)2·H2O (P212121), Sr(NH2SO3)2·4H2O (C2/c), Sr(NH2SO3)2·H2O (P21/c) and Ba(NH2SO3)2 (Pna21) could be obtained as cm-sized crystals from aqueous solutions of the corresponding metal carbonates, hydroxides and amidosulphonic acid, respectively, by careful control of the crystallisation conditions. β-Sr(NH2SO3)2 (Pc) and α-Sr(NH2SO3)2 (P21) could be obtained by careful thermal dehydration of Sr(NH2SO3)2·H2O. Their crystal structures were determined by single-crystal XRD and revealed a rich structural diversity with a significant tendency to form non-centrosymmetric crystals. The compounds were characterised by powder XRD, FT-IR, Raman and UV/vis spectroscopy and thermogravimetry. Temperature programmed single-crystal XRD, powder XRD and Raman spectroscopy, as well as DFT calculations were employed to aid the interpretation of vibrational and thermal properties. For the first time, SHG measurements were performed on metal amidosulphates, revealing the SHG intensities of β-Sr(NH2SO3)2 and Ba(NH2SO3)2 that were comparable to quartz and KDP. Thermal decomposition was additionally studied by the preparation of reaction intermediates, serendipitously revealing the formation of S4N4 as the decomposition product. This unprecedented reaction represents the first sulphur nitride synthesis process that neither employs a sulphur halide nor elemental sulphur.

Microscopic Characterization of Poly(Sulfur Nitride)

Front Cover: In the article number 2100113, Jörg Kressler and co-workers discuss the morphology of poly(sulfur nitride). In particular, the twinning of crystals has a strong influence on the electrical conductivity. The current–voltage curves as obtained in the AFM Peak Force tunneling mode show the typical ohmic behavior of metals.

Microscopic Characterization of Poly(Sulfur Nitride)

AbstractThe morphology of poly(sulfur nitride) (SNx) in bulk crystals and in thin films is investigated by grazing incidence wide‐angle X‐ray scattering (GI WAXS) and atomic force microscopy (AFM). SNx crystals are grown in S2N2 crystals by topochemical solid‐state polymerization and thin SNx films are prepared by sublimation/repolymerization of SNx or by mechanical deformation of crystals onto silicon substrates. Details of the crystallographic orientation of two different thin films are observed by GI WAXS. PeakForce Tunneling (PF‐TUNA) atomic force microscopy provides information on the electrical conductivity of SNx crystal together with its morphology in the nm range. The current–voltage (I–V) curves show ohmic behavior indicating the metallic nature of SNx.

S6 N2 O15 -A Nitrogen-Poor Sulfur Nitride Oxide, and the Anhydride of Nitrido-tris-Sulfuric Acid.

The reaction of hexachlorophosphazene, P3N3Cl6, with SO3 leads to the new sulfur nitride oxide S6N2O15. The compound displays an extraordinarily low nitrogen content and exhibits a bicyclic cage structure according to the formulation N{S(O)2O(O)2S}3N, with both nitrogen atoms in trigonal planar coordination of sulfur atoms. Interestingly, the new nitride oxide can be also seen as the anhydride of nitrido‐tris‐sulfuric acid, N(SO3H)3.

Computational Predictions for Single Chain Chalcogenide-Based One-Dimensional Materials.

Exfoliation of multilayered materials has led to an abundance of new two-dimensional (2D) materials and to their fabrication by other means. These materials have shown exceptional promise for many applications. In a similar fashion, we can envision starting with crystalline polymeric (multichain) materials and exfoliate single-chain, one-dimensional (1D) materials that may also prove useful. We use electronic structure methods to elucidate the properties of such 1D materials: individual chains of chalcogens, of silicon dichalcogenides and of sulfur nitrides. The results indicate reasonable exfoliation energies in the case of polymeric three-dimensional (3D) materials. Quantum confinement effects lead to large band gaps and large exciton binding energies. The effects of strain are quantified and heterojunction band offsets are determined. Possible applications would entail 1D materials on 3D or 2D substrates.

Density functional and ab initio investigation of S2N2 and (SN)2

Quantum chemical calculations were performed to calculate the molecular properties of the 1Ag state of disulfur dinitride, S2N2, and the 1A1 state of the SN dimer, (SN)2, using density functional theory (DFT) and ab initio methods. The molecular structure of (SN)2 is a trapezoid instead of a rectangle. Because the multireference character of (SN)2 is considerable, most hybrid DFTs poorly describe its molecular properties. In contrast, old generalized gradient approximations give qualitatively correct descriptions of the molecular properties of (SN)2. Multi-state second-order multiconfigurational perturbation theory gives results that are close to those from multireference configuration interaction with the Davidson correction. The multireference character should be considered when calculating the molecular properties of poly sulfur nitride systems.

Stability of Sulfur Nitrides: A First-Principles Study

A systematic computational study on the structural, electronic, and bonding properties of binary sulfur nitrides has been performed using the projector augmented wave method based on density functional theory. The pressure–composition phase diagram of the S–N system has been established. The simulated pressure–temperature phase diagram and X-ray diffraction pattern of (SN)x explain the experimentally observed two-phase coexistence. The crystal structure of experimentally observed orthorhombic (SN)x is predicted. The high-pressure phase transition of (SN)x has been studied. Sulfur–sulfur interactions induced by localized sulfur 3pz electrons are found in the high-pressure phase of (SN)x. With increasing nitrogen composition, the coordination number of sulfur atoms increases from two to six in the S–N system. Furthermore, two nitrogen-rich sulfur nitrides SN2 and SN4 have been found at high pressure. SN4 exhibits a high energy density (2.66 kJ·g–1), which makes it potentially interesting for industrial appl...

Metallic and semiconducting 1D conjugated polymers based on –S–C $$\equiv $$ ≡ C– repeating units in poly(sulfur acetylide)

The existence and the properties of a new 1D conjugated polymer, poly(sulfur acetylide), with –S–C\(\equiv \)C– repeating unit are predicted on the basis of density functional theory calculations. Depending on the conformation of the polymer, specifically on the C–S–C angles, the corresponding material is either a metallic conductor (C–S–C near linear) or a semiconductor (C–S–C not linear). It is a semiconductor with 1.6 eV band gap in the minimum energy conformation bent geometry. The polymer can be stretched out at a relatively large and impractical energy cost of 2.6 eV per –S–C\(\equiv \)C– unit upon which it becomes a metallic conductor. However, this semiconductor–metal transition appears to be unique in as much as it happens along a bending mode of the polymeric backbone. This new material appears to be easy to synthesize and is expected to be stable under normal conditions. Despite its simplicity and close relation to other well-known 1D conjugated polymers, such as poly(sulfur nitride) \(\hbox {(SN)}_{x}\), polyacetylene \(\hbox {(CH)}_{x}\) or polyyne (–C\(\equiv \)C–)\(_{x}\), poly(sulfur acetylide) still remains to be explored.

The First Observation of theE,ZConfiguration Of Ar–X–N=S=N–X–Ar (X = S, Se) Chains in the Crystalline State

AbstractNew oligomeric analogues of poly(sulfur nitride), i.e. 3‐ClC6R4–X–N=S=N–X–C6R4Cl‐3 (5–8; R = H, F and X = S, Se), were synthesized and structurally characterized in the solid state by single‐crystal XRD, in solution by variable‐temperature NMR spectroscopy and in the gas phase with DFT/B3LYP calculations. In the crystal, compounds5–7display the well‐knownZ,Zconfiguration, whereas8(R = F, X = Se) is the first compound to display theE,Zconfiguration amongst twelve structurally defined Ar–X–N=S=N–X–Ar (X = S, Se) derivatives in the hydrocarbon and fluorocarbon series. Through a careful analysis of the packing schemes and the intermolecular interactions of the various compounds, an explanation of the abnormal behaviour of8is put forward.

ChemInform Abstract: Sulfur Nitride in Organic Chemistry. Part 19. Selective Formation of Benzo- and Benzobis(1,2,5)thiadiazole Skeleton in the Reaction of Tetrasulfur Tetranitride with Naphthalenols and Related Compounds.

Tetrasulfur tetranitride (N4S4) reacted with 2-naphthols to afford naphtho [1,2-c][1,2,5] thiadiazoles (13) in high yields, while 1-naphthaols gave naphtho[1,2-c:3,4-c′]bis[1,2,5]thiadiazoles as a ...

Field emission pressure sensors with non-silicon membranes

We report on the fabrication of cold cathode emitter and the design parameter simulation of a functional field emission-based pressure sensor. This device comprises a membrane made of metallic compound acting as the anode in front of a flat cold cathode emitter. First, the mechanical deflection of a diaphragm under selected input pressures is modeled. The current density distribution in the deflected diaphragm is then calculated using realistic field emission characteristics from fabricated sulfur doped boron nitride (S-BN) cold cathode device. The total current output was found by integrating the measured current density of the fabricated electron emitter device over the entire diaphragm area of the membrane as function of external pressure. The results show that conventional silicon membranes would pose problems when implemented in a real field emission device, and show how the use of unconventional materials (i.e., TiN) can help overcome these problems.

Solution-processable conjugated polymers containing alternating 1-alkyl-1,2,4-triazole and NSN links

Poly(sulfur nitride), [SN]x, is an infinite π-bonded system and only known polymeric superconductor composed of nonmetallic elements. The appealing electronic properties of [SN]x, along with the safety issue involved in the synthesis, have motivated research on [SN]x analogues, for example, conjugated polymers consisting of sulfur–nitrogen moieties separated by heterocyclic groups. In this paper, we report an exploration for a new NSN-linked polymer, with a major objective to improve its solubility for low-cost, large-area fabrication of molecular devices based on a solution process. Specifically, we present the synthesis and characterization of a conjugated polymer based on alternating 1-alkyl-1,2,4-triazole and sulfur–nitrogen. We found that 4-dimethylamino pyridine is an effective catalyst for the polymerization of bis-N-sulfinyl-3,5-diamino-1-dodecyl-1,2,4-triazole, resulting in polymers that show a broad absorption band in the range of 400 to 600 nm. Moreover, this polymer exhibits high solubility in a variety of non-polar solvents, including tetrahydrofuran, chloroform, dichloromethane, and chlorobenzene.

The use of the hartree-fock-slater eigenvalues to estimate excitation and ionization energies in sulfur-nitrogen compounds

Total statistical energy differences for electronic excitation energies and ionization potentials are expanded in a McLaurin series leading to one-electron energy terms plus correction terms. The different nature of the correction to the one-electron values for the above properties in the Hartree–Fock–Slater scheme as compared to the Hartree–Fock method is commented on. Examples are provided comparing excitation energies and ionization potentials from experiment, transition state method, total statistical energy differences, and one-electron estimates for several sulfur nitrides.

A brief history of the development of organic and polymeric photovoltaics

In this paper an overview of the development of organic photovoltaics is given, with emphasis on polymer-based solar cells. The observation of photoconductivity in solid anthracene in the beginning of the 19th century marked the start of this field. The first real investigations of photovoltaic (PV) devices came in the 1950s, where a number of organic dyes, particularly chlorophyll and related compounds, were studied. In the 1980s the first polymers (including poly(sulphur nitride) and polyacetylene) were investigated in PV cells. However, simple PV devices based on dyes or polymers yield limited power conversion efficiencies (PCE), typically well below 0.1%. A major breakthrough came in 1986 when Tang discovered that bringing a donor and an acceptor together in one cell could dramatically increase the PCE to 1%. This concept of heterojunction has since been widely exploited in a number of donor–acceptor cells, including dye/dye, polymer/dye, polymer/polymer and polymer/fullerene blends. Due to the high electron affinity of fullerene, polymer/fullerene blends have been subject to particular investigation during the past decade. Earlier problems in obtaining efficient charge carrier separation have been overcome and PCE of more than 3% have been reported. Different strategies have been used to gain better control over the morphology and further improve efficiency. Among these, covalent attachment of fullerenes to the polymer backbone, creating so-called double-cable polymers, is the latest. The improved PCE of plastic solar cells combined with increased (shelf and operating) lifetime, superior material properties and available manufacturing techniques may push plastic PVs to the market place within a few years.