Single-phase melem (2,5,8-triamino-tri-s-triazine) C6N7(NH2)3 was obtained as a crystalline powder by thermal treatment of different less condensed C−N−H compounds (e.g., melamine C3N3(NH2)3, dicyandiamide H4C2N4, ammonium dicyanamide NH4[N(CN)2], or cyanamide H2CN2, respectively) at temperatures up to 450 °C in sealed glass ampules. The crystal structure determined ab initio X-ray diffractometry (Cu Kα1: P21/c (No. 14), = 739.92(1) pm, b 865.28(3) c 1338.16(4) β 99.912(2)°, and Z 4). In the...

The first detailed structural characterisation of a functionalised tri-s-triazine derivative, trichloro-tri-s-triazine, is reported, which promising starting material for numerous compounds including graphitic C3N4 phases. DFT calculations show that structure based on should exist and it ∼30 kJ mol−1 more stable than the previously reported phase lowest energy.

We systematically investigate trends in carbon nitride structures targeting the lowest energy configuration of C3N4. Layered conformations, sp2-bonded, turn out to be more favorable than denser, sp3-bonded, networks. Among layered structures, those comprising heptazine motif are consistently lower when compared triazine-based models. Additional decrease is achieved by corrugation layers, driven avoiding repulsive interactions between nitrogen lone-pairs. Consequences such curvature for one...

Analytical performance characteristics of a new vacuum ultraviolet (VUV) detector for gas chromatography (GC) are reported. GC-VUV was applied to hydrocarbons, fixed gases, polyaromatic fatty acids, pesticides, drugs, and estrogens. Applications were chosen feature the sensitivity universal detection capabilities VUV detector, especially cases where mass spectrometry has been limited. Virtually all chemical species absorb have unique phase absorption cross sections in approximately 120-240...

The magnetism in graphene due to single-atom defects is examined by using spin-polarized density functional theory. magnetic moment per defect substitutional atoms and vacancy dependent on the of defects, while that adatom independent defects. It reduces zero with decrease atoms. However, it increases vacancies. sheet B adatoms nonmagnetic, but C N magnetic. distort near perpendicular sheet. distortion significant, very small. atom (B, N) are planar sense there in-plane displacement Upon...

Ultra‐high temperature ceramics (UHTCs) represent an emerging class of materials capable providing mechanical stability and heat dissipation upon operation in extreme environments, e.g., fluxes, chemically reactive plasma conditions. In the last few decades, remarkable research efforts progress were done concerning physical properties UHTCs as well their processing. Moreover, there are vivid activities related to developing synthetic access pathways with high purity, tunable composition,...

The physical properties of the new cubic phase Hf3N4 as well isomorphic Zr3N4 and Ti3N4 are studied using first-principles calculations. Hf3N4, Zr3N4, semiconductors with band gaps 1.8, 1.1, 0.6 eV, respectively. structure is characterized by simultaneous presence steep extremely flat bands. calculated shear modulus G indicates that will be harder than mononitride HfN. At ambient conditions, modifications M3N4 (M=Hf, Zr, Ti) metastable respect to orthorhombic phases, but phases stable...

Organosilicon carbodiimides have been successfully applied as single-source precursor compounds for the synthesis of novel ternary Si-, C-, and N-containing solid phases. Their thermally induced decomposition gives either amorphous silicon carbonitrides or polycrystalline nitride carbide mixtures, materials that are presently technological interest their exceptional hardness, strength, toughness, high temperature resistance even in corrosive environments. This review is concerned with...

A series of thermally stable, easily isolable, monomeric, and isoleptic coinage metal alkyne complexes have been reported. Treatment [N{(C(3)F(7))C(Dipp)N}(2)]Li (the lithium salt the 1,3,5-triazapentadiene [N{(C(3)F(7))C(Dipp)N}(2)]H) with AuCl, CF(3)SO(3)Ag or CF(3)SO(3)Cu in presence 3-hexyne led to corresponding complex [N{(C(3)F(7))C(Dipp)N}(2)]M(EtC[triple bond]CEt) good yield (M = Au, Ag, Cu; Dipp 2,6-diisopropylphenyl). X-ray crystal structures three alkynes are remarkably similar,...

One of the major hurdles in development antimicrobial peptide (AMP)-based materials is their poor capacity selectively killing bacteria without harming nearby mammalian cells. Namely, they are but cytotoxic. Current methods nanoparticle-encapsulated AMPs to target still have not yet overcome this hurdle. Here, we demonstrate a simple effective method address daunting challenge by associating natural AMP with β-sheet-forming synthetic peptide. The integrated peptides self-assembled form...

Extreme chemistry: The carbon nitride imide C2N2(NH) is synthesized from the single-source precursor 1-cyanoguanidine under high-pressure and high-temperature conditions in a laser-heated diamond-anvil cell. Characterization of single crystals recovered at ambient reveals that new compound adopts defect wurtzite structure (see picture).

Gauge including projector augmented wave (GIPAW) NMR calculations combined with hybrid Monte Carlo/molecular dynamics simulations are carried out in order to investigate the relationships between oxygen-17 and silicon-29 spectra of vitreous silica its local structure terms Si−O−Si bond angle Si−O distance distributions. Special attention is paid parameters three- four-membered rings, effect their concentration on glass density studied. It shown that our provide a new insight into features...

Abstract The description of structural relations between bixbyite‐ and corundum‐type structures is particular interest because the common occurrence both structures. One representative examples bixbyite to corundum transition high‐pressure high‐temperature synthesis indium oxide. wet chemistry stabilisation In 2 O 3 under ambient pressure conditions calls for a re‐interpretation InO phase diagram as well clarification transitions in . questions be clarified stability present work we studied...

Atomic clusters of 13, 55, and 147 atoms Fe, Co, Ni with several values total magnetic moments were scanned, minimum energy respect to the moment was searched using ab initio calculations based on spin-polarized density functional theory. After complete structural relaxation icosahedral cuboctahedral retain their initial symmetry. However, anticuboctahedral ${\text{Fe}}_{13}$, after relaxation, adopted bcc-like structure while ${\text{Co}}_{13}$ ${\text{Ni}}_{13}$ finally ${C}_{2V}$ It found...

Based on ab initio density functional theory we present electronic properties and the optical response for Si nanocrystals embedded in amorphous SiO2 networks. Quasi-spherical dots with diameters from 0.8 to 1.6 nm are investigated. The results compared corresponding hydrogenated of same size. calculations show influence interface between nanocrystal matrix properties. recent experimental data discussed detail. As striking features, strong reductions gaps their diameter variation predicted...

We investigate elements comprising the atomistic structure of amorphous silicon oxycarbide ceramics: glassy SiCO, "free" carbon, and interface between them. Using a network modeling approach we generate wide variety models, incorporating different hypotheses atomic arrangements. The models are subsequently treated within density functional theory including ab initio molecular dynamic simulations. Analyzing energy optimized find that enthalpy formation SiCO increases with increasing phase...

Cationic gold carbonyl complexes supported by N-heterocyclic carbene ligands, SIDipp and IDipp, have been synthesized. [(SIDipp)Au(CO)][SbF6] has a linear, two-coordinate center. [(IDipp)Au(CO)][SbF6] display CO values at 2197 2193 cm−1, respectively. Computational studies on [(SIMe)Au(CO)]+ indicate the presence of strong Au(I)–CO bond.

The way is open for the physical and chemical characterization single-crystal growth of orthorhombic o′-In2O3 polymorph. Orthorhombic In2O3 synthesized from rhombohedral corundum-type rh-In2O3 under moderately high-pressure high-temperature conditions (8–9 GPa, 600–1100 °C) followed by recovery to ambient pressure temperature. crystal-structure data at confirm unambiguously Rh2O3(II)-type structure.