Isomer-specific photofragmentation of C3H3+ at the carbon K-edge.

Individual fingerprints of different isomers of C3H3+ cations have been identified by studying photoionization, photoexcitation, and photofragmentation of C3H3+ near the carbon K-edge. The experiment was performed employing the photon-ion merged-beams technique at the photon-ion spectrometer at PETRA III (PIPE). This technique is a variant of near-edge X-ray absorption fine-structure spectroscopy, which is particularly sensitive to the 1s → π* excitation. The C3H3+ primary ions were generated by an electron cyclotron resonance ion source. C3Hn2+ product ions with n = 0, 1, 2, and 3 were observed for photon energies in the range of 279.0 eV to 295.2 eV. The experimental spectra are interpreted with the aid of theoretical calculations within the framework of time-dependent density functional theory. To this end, absorption spectra have been calculated for three different constitutional isomers of C3H3+. We find that our experimental approach offers a new possibility to study at the same time details of the electronic structure and of the geometry of molecular ions such as C3H3+.

Chiral-at-Metal Racemization Unraveled for MX2 (a-chel)2 by means of a Computational Analysis of MoO2 (acnac)2.

Octahedral chiral-at-metal complexes MX2 (a-chel)2 (a-chel=asymmetric chelate) can rearrange their ligands by four mechanisms known as the Bailar (B), Ray-Dutt (RD), Conte-Hippler (CH), and Dhimba-Muller-Lammertsma (DML) twists. Racemization involves their interconnections, which were computed for MoO2 (acnac)2 (acnac=ß-ketoiminate) using density functional theory at ωB97x-D with the 6-31G(d,p) and 6-311G(2d,p) basis sets and LANL2DZ for molybdenum. Racemizing the cis(NN) isomer, being the global energy minimum with trans oriented imine groups, is a three step process (DML-CH-DML) that requires 17.4 kcal/mol, while all three cis isomers (cis(NN), cis(NO), and cis(OO)) interconvert at ≤17.9 kcal/mol. The B and RD twists are energetically not competitive and neither are the trans isomers. The interconnection of all enantiomeric minima and transition structures is summarized in a graph that also visualizes valley ridge inflection points for two of the three CH twists. Geometrical features of the minima and twists are given. Lastly, the influence of N-substitution on the favored racemization pathway is evaluated. The present comprehensive study serves as a template for designing chiral-at-metal MX2 (a-chel)2 catalysts that may retain their chiral integrity.

Chiral-at-Metal Racemization Unraveled for MX2 (a-chel)2 by Means of a Computational Analysis of MoO2 (acnac)2.

Invited for the cover of this issue are Koop Lammertsma and co-workers at the University of Johannesburg and Vrije Universiteit Amsterdam. The image of the kudu's antlers depicts the isomerization and racemization of the chiral-at-metal complex MoO2(acnac)2 (acnac=ß-ketoiminate). Read the full text of the article at 10.1002/chem.202302516.

Lanthanum-1,2,3-Triazole-Based 2D Coordination Polymer is an Efficient Catalyst for the Oxidation of Olefins.

A new two-dimensional (2D) coordination polymer (CP) [La(C18H14N3O6)2(H2O)(OH)]n has been prepared from a 1,2,3-triazole linker and lanthanum nitrate hexahydrate in DMF. The La-CP was characterized by single-crystal X-ray crystallography, highlighting the binding motif at La ions and the fact that the material contains channels with entrapped solvent. The CP showed good catalytic activity for the oxidation of a wide variety of olefins (linear, cyclic, aromatic, and functionalized alkenes) to aldehydes. Mechanistic studies show that the oxidation reaction proceeds via a non-free-radical mechanism. The catalyst could be recovered and reused five times without major changes in activity for the oxidation of styrene to benzaldehyde.

Racemization Pathway for MoO2(acac)2 Favored over Ray-Dutt, Bailar, and Conte-Hippler Twists.

Chiral cis-MoO2(acac)2 racemizes via four pathways that agree with and extend upon Muetterties' topological analysis for dynamic MX2(chel)2 complexes. Textbook Ray-Dutt and Bailar twists are the least favored with barriers of 27.5 and 28.7 kcal/mol, respectively. Rotating both acac ligands of the Bailar structure by 90° gives the lower Conte-Hippler twist (20.0 kcal/mol), which represents a valley-ridge inflection that invokes the trans isomer. The most favorable is a new twist that was found by 90° rotation of only one acac ligand of the Bailar structure. The gas-phase barrier of 17.4 kcal/mol for this Dhimba-Muller-Lammertsma twist further decreases upon inclusion of the effects of solvents to 16.3 kcal/mol (benzene), 16.2 kcal/mol (toluene), and 15.4 kcal/mol (chloroform), which are in excellent agreement with the reported experimental values.

X-Ray absorption spectroscopy of H3O.

We report the X-ray absorption of isolated H3O+ cations at the O 1s edge. The molecular ions were prepared in a flowing afterglow ion source which was designed for the production of small water clusters, protonated water clusters, and hydrated ions. Isolated H2O+ cations have been analyzed for comparison. The spectra show significant differences in resonance energies and widths compared to neutral H2O with resonances shifting to higher energies by as much as 10 eV and resonance widths increasing by as much as a factor of 5. The experimental results are supported by time-dependent density functional theory calculations performed for both molecular cations, showing a good agreement with the experimental data. The spectra reported here could enable the identification of the individual molecules in charged small water clusters or liquid water using X-ray absorption spectroscopy.

Synthesis, anti-microbial, toxicity and molecular docking studies of N-nitroso-N-phenylhydroxylamine (cupferron) and its derivatives.

Bacterial resistance to antimicrobial agents is increasing at an alarming rate globally and requires new lead compounds for antibiotics. In this study, N-phenyl-N-nitroso hydroxylamine (cupferron) and its derivatives have been synthesised using readily available starting materials. The compounds were obtained in high yield and purity. They show activity towards a range of Gram-positive and Gram-negative pathogenic bacteria, with minimum inhibitory concentration (MIC) values as low as 2 µg.mL-1 against the tested organisms, especially for Gram-positive species. Toxicity studies on the lead compound 3b indicate insignificant effects on healthy cell lines. Molecular docking studies on the lead compound identify possible binding modes of the compound, and the results obtained correlate with those of in vitro and MIC studies. The lead compound shows excellent drug-likeness properties.

Pathophysiological and cognitive mechanisms of fatigue in multiple sclerosis.

Fatigue is one of the most common symptoms in multiple sclerosis (MS), with a major impact on patients' quality of life. Currently, treatment proceeds by trial and error with limited success, probably due to the presence of multiple different underlying mechanisms. Recent neuroscientific advances offer the potential to develop tools for differentiating these mechanisms in individual patients and ultimately provide a principled basis for treatment selection. However, development of these tools for differential diagnosis will require guidance by pathophysiological and cognitive theories that propose mechanisms which can be assessed in individual patients. This article provides an overview of contemporary pathophysiological theories of fatigue in MS and discusses how the mechanisms they propose may become measurable with emerging technologies and thus lay a foundation for future personalised treatments.

Absorption spectra at the iodine 3d ionisation threshold following the CHxI+ (x = 0-3) cation sequence.

Yields of atomic iodine Iq+ (q≥ 2) fragments resulting from photoexcitation and photoionisation of the target cations CHxI+ (x = 0-3) have been measured in the photon-energy range 610 eV to 670 eV, which comprises the threshold for iodine 3d ionisation. The measured ion-yield spectra show two strong and broad resonance features due to the excitation of the 3d3/2,5/2 electrons into εf states similar to atomic iodine. In the 3d pre-edge range, electrons are excited into molecular orbitals consisting of iodine, carbon, and hydrogen atomic orbitals. These transitions have been identified by comparison with literature data and by simulations using time-dependent density functional theory (TDDFT) with the KMLYP functional. The ion-yield spectrum for CH3I+ resembles the spectrum of IH+ [Klumpp et al., Phys. Rev. A, 2018, 97, 033401] because the highest occupied molecular orbitals (HOMO) of the H and CH3 fragments both contain a single vacancy, only. For the molecular cations with higher number of vacancies in the valence molecular orbitals CHxI+ (x = 0-2), a stronger hybridisation of the molecular orbitals occurs between the organic fragment and the iodine resulting in a change of bonding from a single σ bond in CH3I+ to a triple bond including two π orbitals in CI+. This is reflected in the resonance energies of the observed absorption lines below the iodine 3d excitation threshold.

Inner-shell X-ray absorption spectra of the cationic series NHy+ (y = 0-3).

Ion yields following X-ray absorption of the cationic series NHy+ (y = 0-3) were measured to identify the characteristic absorption resonances in the energy range of the atomic nitrogen K-edge. Significant changes in the position of the absorption resonances were observed depending on the number of hydrogen atoms bound to the central nitrogen atom. Configuration interaction (CI) calculations were performed to obtain line assignments in the frame of molecular group theory. To validate the calculations, our assignment for the atomic cation N+, measured as a reference, was compared with published theoretical and experimental data.

Conversion of Atrial Fibrillation after Cardiosurgical Procedures by Vernakalant® as an Atrial Repolarization Delaying Agent (ARDA).

BACKGROUND: Postoperative, new-onset atrial fibrillation (POAF) is one of the most common complications after cardiosurgical procedures. Vernakalant has been reported to be effective in the conversion of POAF. The aim of this study was to evaluate the efficacy and safety of vernakalant for atrial fibrillation after cardiac operations, and to investigate predictors for the success of vernakalant treatment. Patients and Methods: Post-cardiac surgery patients with new-onset of atrial fibrillation (AF) were consecutively enrolled in this study. Demographic data as well as intraoperative and postoperative parameters were analyzed. Vernakalant administration was primarily started 5.5 hours after new-onset POAF: 3 mg/kg intravenously over 10 min, and in case of non-conversion, a second dose of 2 mg/kg intravenously over 10 min. Results: 129 consecutive patients (70.2 ± 9.1 years) were included: 61 patients with coronary artery bypass graft (CABG) surgery, 49 patients with isolated valve procedures, and 19 patients with combined procedures (CABG and valve). Conversion in sinus rhythm was achieved after the first vernakalant dose in 57 patients (44%), and after the second dose in 41 patients (32%). The mean time to conversion was 13.7 ± 14.1 min. The patients receiving valve procedures depicted a significantly lower conversion rate. The following variables lowered conversion rate: no preoperative beta blocker, postoperative troponin levels >500 ng/L, and systolic blood pressure >140 mmHg. At the first follow-up, 92% of the converted patients showed sinus rhythm, while 80% of the non-responders showed sinus rhythm (P < .01). Conclusions: The POAF was effectively converted by vernakalant. The conversion rate of POAF after valve surgery was lower when compared to isolated CABG.

(η6-Benzene)-chlorido-[(S)-2-(4-isopropyl-4,5-di-hydro-oxazol-2-yl)phenolato]ruthenium(II).

The title compound, [Ru(C12H14NO2)Cl(η6-C6H6)], exhibits a half-sandwich tripod stand structure and crystallizes in the ortho-rhom-bic space group P212121. The arene group is η6 π-coordinated to the Ru atom with a centroid-to-metal distance of 1.6590 (5) Å, with the (S)-2-(4-isopropyl-4,5-di-hydro-oxazol-2-yl)phenolate chelate ligand forming a bite angle of 86.88 (19)° through its N and phenolate O atoms. The pseudo-octa-hedral geometry assumed by the complex is completed by a chloride ligand. The coordination of the optically pure bidentate ligand induces metal centered chirality onto the complex with a Flack parameter of -0.056.

Prop-2-ynyl 3-meth-oxy-4-(prop-2-yn-yloxy)benzoate.

The title compound, C14H12O4, comprises of two crystallographically independent mol-ecules in the asymmetric unit, linked via C-H⋯O inter-actions to form dimeric entities. The allylic groups are twisted out of the phenyl planes with dihedral angles varying between 7.92 (13) and 25.42 (8)°. In the crystal, the packing follows a zigzag pattern along the c-axis direction. The absolute configuration of the sample could not be determined reliably.

1,2,3-triazole and chiral Schiff base hybrids as potential anticancer agents: DFT, molecular docking and ADME studies.

A series of novel 1,2,3-triazole and chiral Schiff base hybrids 2-6 were synthesized by Schiff base condensation reaction from pre-prepared parent component of the hybrids (1,2,3-triazole 1) and series of primary chiral amines and their chemical structure were confirmed using NMR and FTIR spectroscopies, and CHN elemental analysis. Compounds 1-6 were evaluated for their anticancer activity against two cancer PC3 (prostate) and A375 (skin) and MRC-5 (healthy) cell lines by Almar Blue assay method. The compounds exhibited significant cytotoxicity against the tested cancer cell lines. Among the tested compounds 3 and 6 showed very good activity for the inhibition of the cancer cell lines and low toxicity for the healthy cell lines. All the compounds exhibited high binding affinity for Androgen receptor modulators (PDB ID: 5t8e) and Human MIA (PDB ID: 1i1j) inhibitors compared to the reference anticancer drug (cisplatin). Structure activity relationships (SARs) of the tested compounds is in good agreement with DFT and molecular docking studies. The compounds exhibited desirable physicochemical properties for drug likeness.

Comparative investigation of derivatives of (E)-N-((E)-3-phenylallylidene)aniline: Synthesis, structural characterization, biological evaluation, density functional theory analysis, and in silico molecular docking.

Bacterial resistance to antibiotics poses a significant global challenge for the public sector. Globally, researchers are actively investigating solutions to tackle the issue of bacterial resistance to antibiotics, with Schiff bases standing out as promising contenders in the fight against antimicrobial resistance. This study focused on synthesizing a series of Schiff bases (CA1-CA10) by reacting cinnamaldehyde with various aniline derivatives. Various analytical techniques, such as NMR, FTIR, UV-Vis, elemental analysis, and mass spectrometry, were employed to elucidate the structures of the synthesized compounds. Furthermore, crystal structure of CA8 was obtained using single crystal X-ray spectroscopy. The compounds were subjected to in vitro testing to assess their antibacterial and antifungal properties against eleven bacterial strains and four fungal strains. The results revealed diverse activity levels against the pathogens at varying concentrations, with notable potency observed in compounds CA3, CA4, CA9, and CA10, as indicated by their minimum inhibitory concentrations (MIC) values. The observed activity of the compounds seemed to be influenced by the specific substituents attached to their molecular structure. By conducting computational and molecular docking studies, the electronic properties of the compounds were investigated, further substantiating their potential as effective antimicrobial agents.

(Biphenyl-2,2'-di-yl)di-tert-butyl-phos-phonium trifluoro-methane-sulfonate.

To aid in the elucidation of catalytic reaction mechanism of palladacycles, we found that reaction of trifluoro-methane-sulfonic acid with a phosphapalladacycle resulted in elimination of the palladium and formation of the title phospholium salt, C20H26P(+)·CF3SO3(-). Selected geometrical parameters include P-biphenyl (av.) = 1.801 (3) Šand P-t-Bu (av.) = 1.858 (3) Å, and significant distortion of the tetra-hedral P-atom environment with biphen-yl-P-biphenyl = 93.93 (13)° and t-Bu-P-t-Bu = 118.82 (14)°. In the crystal, weak C-H⋯O inter-actions lead to channels along the c axis that are occupied by CF3SO3(-) anions.

P,P-Bis[4-(dimethyl-amino)-phen-yl]-N,N-bis-(propan-2-yl)phosphinic amide.

The mol-ecular structure of the title compound, C(22)H(34)N(3)OP, adopts a distorted tetra-hedral geometry at the P atom, with the most noticeable distortion being for the O-P-N angle [117.53 (10)°]. An effective cone angle of 187° was calculated for the compound. In the crystal, weak C-H⋯O inter-actions create infinite chains along [100], whereas C-H⋯π inter-actions propagating in [001] generate a herringbone motif.

rac-[2-(Dicyclohexylphosphanyl)phenyl](phenyl)phosphinic diisopropyl-amide-borane hemihydrate.

In the title compound, C(30)H(48)BNOP(2)·0.5H(2)O, the water molecule is disordered about an inversion centre. Both phospho-rus atoms shows distortions in their tetra-hedral environments with the cyclo-hexyl substituents disordered over two orientations in a 0.851 (3):0.149 (3) occupancy ratio. The crystal structure is assembled via O-H⋯O inter-actions between pairs of phosphininc amide mol-ecules and water molecules, creating hydrogen-bonded dimers with graph-set R(2) (4)(8) along [001]. Weak C-H⋯O inter-actions are also observed.

(2,2'-Bipyrid-yl)(η6-p-cymene)iodidoruthenium(II) hexa-fluorido-phosphate.

The title compound, having the mol-ecular formula [RuI(η6-C10H14)(C10H8N2)]PF6, crystallizes in the triclinic P (Z = 2) space group as a half-sandwich complex resembling a three-legged piano stool. Important geometrical parameters include Ru-cymene centroid = 1.6902 (17) Å, Ru-I = 2.6958 (5) Å, [Ru-N]avg = 2.072 (3) Å, N1-Ru-N2 = 76.86 (12)° and a dihedral angle between the planes of the two rings of the bipyridyl system of 5.9 (2)°. The PF6 - ion was treated with a twofold disorder model, refining to a 65.0 (8):35.0 (8) occupancy ratio. The crystal packing features C-H⋯F/I inter-actions.

trans-Bis[bis-(di-phenyl-phosphan-yl)methane-κ2P,P']di-chlorido-ruthenium(II): a triclinic polymorph.

The title compound, [RuCl2(C25H22P2)2] or [RuCl2(dppm)2] (dppm = bis-(di-phenyl-phosphan-yl)methane, C25H22P2) crystallizes as two half-mol-ecules (completed by inversion symmetry) in space group P (Z = 2), with the RuII atoms occupying inversion centers at 0,0,0 and 1/2, 1/2, 1/2, respectively. The bidentate phosphane ligands occupy equatorial positions while the chlorido ligands complete the distorted octa-hedral coordination spheres at axial positions. The bite angles of the phosphane chelates are similar for the two mol-ecules [(P-Ru-P)avg. = 71.1°], while there are significant differences in the twisting of the methyl-ene backbone, with a distance of the methyl-ene C atom from the RuP4 plane of 0.659 (2) and 0.299 (3) Å, respectively, and also for the phenyl substituents for both mol-ecules due to variations in weak C-H⋯Cl inter-actions.