NCN Group Research Articles

Tubular graphene-supported nanoparticulate manganese carbodiimide as a free-standing high-energy and high-rate anode for lithium ion batteries

Combination of high-energy density and high-power density is highly pursued in the development of advanced lithium ion batteries (LIBs). In this paper, we fabricate a free-standing anode composed of tubular graphene-supported nanoparticulate manganese carbodiimide (TG/MnNCN) for high-energy and high-power LIBs. MnNCN nanoparticles conformally coated three-dimensional TG with high surface area provide abundant active sites for electrochemical reaction and the high conductivity of TG facilitates intrinsic electron pathways and efficient ion transport channels. More importantly, the non-covalent π-π interaction between NCN group and graphene is beneficial for interfacial charge transport. Consequently, the TG/MnNCN anode exhibits a high areal capacity of 9.8 mA h cm−2 at 0.5 mA cm−2 and a high rate capacity of 3.5 mA h cm−2 at 50 mA cm−2 even at a high mass loading of up to 10 mg cm−2. Excitingly, the TG/MnNCN anode also presents impressive performance in Li-ion full cell (coupled with LiCoO2 cathode) with an outstanding energy density (15.08 mWh cm−2 and 343 Wh kg−1) and power density (378.5 mW cm−2 and 8.7 kW kg−1), indicating the potential for high-energy and high-power LIB applications.

Crystal structure, Hirshfeld surface analysis and inter-action energy and DFT studies of 2-(2,3-di-hydro-1H-perimidin-2-yl)-6-meth-oxy-phenol.

The title compound, C18H16N2O2, consists of perimidine and meth-oxy-phenol units, where the tricyclic perimidine unit contains a naphthalene ring system and a non-planar C4N2 ring adopting an envelope conformation with the NCN group hinged by 47.44 (7)° with respect to the best plane of the other five atoms. In the crystal, O-HPhnl⋯NPrmdn and N-HPrmdn⋯OPhnl (Phnl = phenol and Prmdn = perimidine) hydrogen bonds link the mol-ecules into infinite chains along the b-axis direction. Weak C-H⋯π inter-actions may further stabilize the crystal structure. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (49.0%), H⋯C/C⋯H (35.8%) and H⋯O/O⋯H (12.0%) inter-actions. Hydrogen bonding and van der Waals inter-actions are the dominant inter-actions in the crystal packing. Computational chemistry indicates that in the crystal, the O-HPhnl⋯NPrmdn and N-HPrmdn⋯OPhnl hydrogen-bond energies are 58.4 and 38.0 kJ mol-1, respectively. Density functional theory (DFT) optimized structures at the B3LYP/ 6-311 G(d,p) level are compared with the experimentally determined mol-ecular structure in the solid state. The HOMO-LUMO behaviour was elucidated to determine the energy gap.

Effect of stress severity on zebrafish (Danio rerio) growth, gonadal development and reproductive performance: Do females and males respond differently?

The current trial was carried out to examine the impacts of stress on growth, gonadal development, and reproductive performance in both sexes of zebrafish. In these experiments, adult fish were distributed in nine aquaria and were held for 42 days. Trial treatments included: 1) NCN group (no daily chasing or netting), 2) 1CN group (once a day chasing and netting both for 1 min during 42 days), and 3) 2CN group (twice a day chasing and netting both for 1 min during 42 days). Growth performance, gonadal development and reproductive performance were assessed. After 42 days the fish were sacrificed to allow for the determination of cortisol levels and for histological analysis of the gonads. Female zebrafish in NCN group showed higher growth performance than the stressed groups (P < .05) but no significant differences were found between males in the NCN group and stressed groups (P > .05). Cortisol levels were highest in male zebrafish in 1CN and lowest in males from the NCN groups. Moreover, the highest and lowest female cortisol levels were found in 2CN and NCN treatments, respectively (P < .05). Histological analysis of gonads of the 2CN groups showed that oocytes and testis were in the vitellogenesis and mid-spermatogenesis stages, respectively. Fish in the 2CN groups had a lower latency time to ovulation and NCN group produced more embryos than the other groups (P < .05). These results suggest that chronic stressing events tend to depress growth in both sexes, and reproductive performance in females.

Increased Intrathecal Immune Activation in Virally Suppressed HIV-1 Infected Patients with Neurocognitive Impairment.

ObjectiveAlthough milder forms of HIV-associated neurocognitive disorder (HAND) remain prevalent, a correlation to neuronal injury has not been established in patients on antiretroviral therapy (ART). We examined the relationship between mild HAND and CSF neurofilament light protein (NFL), a biomarker of neuronal injury; and CSF neopterin, a biomarker of CNS immunoactivation, in virally suppressed patients on antiretroviral therapy (ART).Design and MethodsWe selected 99 subjects on suppressive ART followed longitudinally from the CNS HIV Anti-Retroviral Therapy Effects Research (CHARTER) study. Based on standardized comprehensive neurocognitive performance (NP) testing, subjects were classified as neurocognitively normal (NCN; n = 29) or impaired (NCI; n = 70). The NCI group included subjects with asymptomatic (ANI; n = 37) or mild (MND; n = 33) HAND. CSF biomarkers were analyzed on two occasions.ResultsGeometric mean CSF neopterin was 25% higher in the NCI group (p = 0.04) and NFL and neopterin were significantly correlated within the NCI group (r = 0.30; p<0.001) but not in the NCN group (r = -0.13; p = 0.3). Additionally, a trend towards higher NFL was seen in the NCI group (p = 0.06).ConclusionsMild HAND was associated with increased intrathecal immune activation, and the correlation between neopterin and NFL found in NCI subjects indicates an association between neurocognitive impairment, CNS inflammation and neuronal damage. Together these findings suggest that NCI despite ART may represent an active pathological process within the CNS that needs further characterization in prospective studies.

2,2-Dimethyl-2,3-dihydro-1H-perimidine

The title compound, C13H14N2, was obtained from reaction of diaminona­phthalene with acetone. In both independent mol­ecules in the asymmetric unit, the tricyclic perimidine consists of a planar (r.m.s. deviations = 0.0125 and 0.0181 Å) naphthalene ring system and an envelope conformation C4N2 ringwith the NCN group hinged with respect to the naph­thalene backbone by 36.9 (2) and 41.3 (2)° in the two independent molecules. The methyl substituents are arranged approximately axial and equatorial on the apical C atom. In the crystal, one of the N—H groups of one independent mol­ecule is involved in classical N—H⋯N hydrogen bonding. Short inter­molecular (C/N)—H⋯π(arene) inter­actions, near the short T-shaped limit, link mol­ecules in the absence of strong acceptors.

Stabilization of Magnetic Ordering Observed for the Bridging NCN Group

The reaction of meso-tetraphenylporphyrinatomanganese(II) (MnTPP) and N,7,7-tricyanoquinomethanimine (TCQMI) forms {[Mn(III)TPP](+)}(2)[TCQMI](2)(2-), which possesses a one-dimensional chain with μ(1,3)-NCN linkages. The reduced [TCQMI](•-) dimerizes as [TCQMI](2)(2-) with a long, central 1.611(8) Å C-C bond and leads to a honeycomb, two-dimensionally layered structure with 24-membered rings. The μ(1,3)-NCN linkage stabilizes a canted antiferromagnetic (weak ferromagnetic) behavior with T(c) of 3.7 K.

Hückel MO studies on diuretics and carbonic anhydrase inhibitors

The electronic structures of sulfonamide compounds and thiazide derivatives are calculated by means of the Huckel molecular orbital method. The electron densities at nitrogen atom positions in the NCN group of thiazide derivatives are parallel to their diuretic potency. A good correlation is found between the formal charge or the frontier electron density of the lowest vacant level at the amide group position in the sulphonamide group of all these compounds and their inhibitory action against carbonic anhydrase.

Supramolecular Architectures and Magnetic Properties of Self‐Assembled Windmill‐Like Dinuclear Copper(II) Complexes with Purine Ligands

AbstractThree new CuII compounds, [Cu2(μ‐ade)4(H2O)2]·(bpa)·8H2O (1), [Cu2(μ‐Hade)4(H2O)2](NO3)4·2[Cu(pic)2(H2O)]·6H2O (2) and [Cu2(μ‐6Clpur)4(H2O)2]·~6H2O (3) [in which ade = adeninate anion, Hade = 7H‐adenine, 6Clpur = 6‐chloropurinate anion, bpa = 1,2‐bis(4‐pyridyl)ethane, pic = 2‐pyridinecarboxylate anion], are reported. Their crystal structures consist of dinuclear copper(II) units, in which four ligands arranged in a windmill‐like fashion bridge the metal ions through a nonlinear NCN group. Supramolecular crystal building of compound 1 is essentially maintained by an extensive network of hydrogen‐bonding interactions that involves direct contacts between the nucleobases. In contrast, in compound 2 there is no evidence for direct interactions between the nucleobases, but the hydrogen bonds among the nucleobases and nitrate counteranions are especially relevant. Compound 3 is mainly built up from T‐shaped noncovalent Cl···N interactions and hydrogen‐bonding interactions involving the crystallization solvent molecules. Magnetic susceptibility measurements indicate the presence of strong intradimeric antiferromagnetic interactions with large singlet–triplet splittings of –222 (for 1), –288 (for 2) and –255 (for 3) cm–1. DFT calculations were carried out to evaluate the dependence of the magnetic coupling value as a function of some key structural parameters: the Cu–N basal plane distance, the axial Cu–Ow distance and the Cu···Cu distance. DFT calculations also revealed that the nature of the bridging ligand is a crucial factor. In this way, the strength to transmit the magnetic interaction of the different bridging ligands is explained on the basis of the number of electron lone pairs.(© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2009)

A homoleptic molybdenum(IV) enolate complex: synthesis, molecular and electronic structure, and NCN group transfer to form a terminal cyanoimide of molybdenum(VI).

A monomeric molybdenum(IV) tetrakis enolate complex Mo(OC[Ad]Mes)(4), 1, where Ad = 2-adamantylidene and Mes = 2,4,6-Me(3)C(6)H(2), has been synthesized and characterized structurally by X-ray diffraction, chemically through NCN group-transfer reactivity, and computationally to investigate the origins of the observed structure that is intermediate between tetrahedral and square planar. No prior examples of Mo(OR)(4) have been structurally characterized despite having been the subject of both experimental and theoretical interest. Complex 1 has a singlet ground state and thus a metal-based lone pair of electrons. The latter has been visualized with the aid of the electron localization function (ELF) and appears as a two-bladed propeller with D(2)(d)() symmetry. Complex 1 makes a simple 1:1 adduct with t-BuNC that is trigonal bipyramidal with an axial isocyanide as demonstrated by X-ray crystallography. This trigonal bipyramidal 1:1 adduct has a triplet ground state and provides a model for the way in which 1 interacts with NCN group donor dbabhCN prior to NCN group transfer to form the terminal cyanoimide complex 1-NCN. The calculated Mo-N bond dissociation enthalpy for 1-NCN is 104 kcal mol(-1), 30 kcal mol(-1) greater than that for the corresponding dissociation of NCN from cyanophosphiniminato NCNPMe(3).

2-Amino-2-oxazoline and trialkylisourea Pt(ii) complexes derived from organocyanamides

In the di(organocyanamide) complexes trans-[PtCl2(NCNR2)2] (R = Me 1a, Et 1b), prepared by reaction of PtCl2 with the appropriate NCNR2, the cyanamide ligands, activated by coordination, undergo an unprecedented nucleophilic addition, at room temperature, of an haloalcohol (ClCH2CH2OH/LiBun) or of an alcohol (MeOH) to give the corresponding 2-amino-2-oxazoline cis-[PtCl2{NC(OCH2CH2)NR2}2] (R = Me 2a, Et 2b) or trialkylisourea trans-[PtCl2{NHC(OMe)NR2}2] (R = Me 3a, Et 3b) complexes. The X-ray crystal structure of 2b is also reported, indicating a π-bond delocalization along the NCN group of the aminooxazoline ligands.

Bimetallic μ-cyanoimide complexes prepared by NCN group transfer

A cyanoimide [NCN] transfer reagent has been developed and applied to the synthesis of the μ-NCN systems (μ2;η1,η1-NCN) {M[N(R)Ar]3}2 (Ar = C6H3Me2-3,5; M = V or U, R = But; M = Mo, R = Pri).

Spectroscopic, Magnetic, and Electrochemical Studies of a Dimeric N-Substituted-Sulfanilamide Copper(II) Complex. X-ray and Molecular Structure of the Cu(2)(sulfathiazolato)(4) Complex.

A copper(II) complex of formula Cu(2)(stz)(4) (stz(-) = sulfathiazolato) has been synthesized and characterized by single-crystal X-ray diffraction. The compound crystallizes in the orthorhombic system, space group P2(1)cn with a = 10.595(7) Å, b = 14.274(3) Å, c = 29.65(1) Å, and Z = 4. The structure consists of dinuclear copper(II) units which contain four sulfathiazolato ligands bridging the metal ions through a nonlinear NCN group. The copper atoms are four-coordinated, the chromophore being CuN(4). The Cu.Cu bond distance is 2.671(2) Å. Magnetic susceptibility data in the temperature range 7-300 K show the occurrence of intramolecular antiferromagnetic coupling with 2J = -61.5 cm(-1). This low exchange energy value has been analyzed and rationalized through extended Hückel calculations. EPR spectra at X- and Q-band frequencies show the signals corresponding to a dinuclear entity, being the zero-field splitting parameter, D = 0.230 cm(-1).

Pseudoelementverbindungen IX. Organostannylierung von Cyanamidonitrat — Molekül- und Kristallstruktur von N-Trimethylstannyl-N′-nitro-carbodiimid

Abstract Considered under the aspect of its ambidence, the reactivity of cyanamidonitrate [NO2NCN]− towards triorganostannyl chlorides was investigated. The reaction products of type R3Sn-NCN-NO2 were characterized by 1H-NMR, 13C-NMR, 119Sn-NMR and IR spectroscopy. While cyanamides of the type [RnE(Y)NCN]− (RnE(Y) = RC(O), RC(NCN), R2 P(O), R2P(S), R2P(NCN), RSO2) are coordinated exclusively either via the terminal nitrogen (monodentately) or via both the nitrile group end on and the chalcogen atom (bidentately), we found N-triorganostannyl-N′-nitro-carbodiimides as the first example in which the NCN group acts as a bidentate bridge with metal-N bonds in 1- and 3-position. For Me3Sn-NCN-NO2 the crystal structure was determined.

Tetrahydropyrimidine derivatives inhibit binding of a Tat-like, arginine-containing peptide, to HIV TAR RNA in vitro

The ability of a small molecule, 2-methyl,4-carboxy,5-hydroxy-3,4,5,6-tetrahydropyrimidine (THP(A)), which accumulates intracellularly in various streptomyces, to inhibit the interaction of Tat peptide (R52) with TAR RNA is presented. Using gel-shift assay, we found that the inhibition constant K i of THP(A) is 50–100 nM, which is in the range of the binding constants of Tat peptide and protein. THP(A) is ∼ 10 6 times more tightly bound than the free l-arginine. The high binding affinity may be attributed to the special delocalized positive charge on the NCN group and the hydroxyl group at the 5 position of this molecule. A model for THP(A)-TAR interaction, analogous to the arginine guanidinum group-TAR interaction, is presented. The relatively high uptake of THP(A) by mammalian cells warrants in vivo Tat/TAR inhibition studies.