On some controversy regarding νOH assignments in CsH2PO4

Spectroscopic methods such as Raman scattering and IR absorption, as well as structural methods such as x-ray and n-diffraction, offer rather ambiguous interpretation of the high-frequency phonon spectrum of CsH₂PO₄ (CDP), especially regarding the proper assignment of proton vibrational modes. Empirical lattice dynamics (LD) simulations of the proton vibrational density of states ((H-VDOS)) in CDP also reveal a discrepancy in the frequency assignments of the OH stretching modes of its two non-equivalent hydrogen bonds. This may be resolved by accounting for the LD simulated directional (H-VDOS) along the three Cartesian axes of CDP, from which the corresponding anisotropy of the proton kinetic energy tensor can be deduced. The results may then be tested by a simple deep inelastic neutron scattering (DINS) measurement on a single crystal of para-electric CDP at room temperature.     

Rapid synthesis of carbon materials by microwave-assisted hydrothermal method at low temperature and its adsorption properties for uranium (VI)

The cathelicidin-derived peptide (CDP1) is a human antimicrobial peptide that preferentially targets bacterial membranes in response to infection. CDP1 was functionalised with NODAGA and DOTA for complexation with gallium-68 to evaluate its potential as an infection imaging tracer. The synthesis of [⁶⁸Ga]Ga–NODAGA–CDP1 and [⁶⁸Ga]Ga–DOTA–CDP1 were optimised for pH, molarity, incubation time and temperature, and product purification. The integrity and protein binding were investigated employing [⁶⁸Ga]GaCl₃ and [⁶⁸Ga]Ga–DOTA–TATE as internal references. [⁶⁸Ga]Ga–NODAGA–CDP1 displayed good labelling properties with higher product yield compared to [⁶⁸Ga]Ga–DOTA–CDP1. In contrast, [⁶⁸Ga]Ga–DOTA–CDP1 showed better stability and is the preferred candidate for an in vivo investigation.

     

Isolation of a Uranium(III)-Carbon Multiple Bond Complex

Low-valent uranium-element multiple bond complexes remain scarce, though there is burgeoning interest regarding to their bonding and reactivity. Herein, isolation of a uranium(III)-carbon double bond complex [(Cp*)₂U(CDP)](BPh₄) ( 1 ) comprising a tridentate carbodiphosphorane (CDP) was reported for the first time. Oxidation of 1 afforded the corresponding U(IV) complex [(Cp*)₂U(CDP)](BPh₄)₂ ( 2 ). The distance between U and C in 2 is 2.481 Å, indicating the existence of a typical U=C double bond, which is further confirmed by quantum chemical calculations. Bonding analysis suggested that the CDP also serves as both σ- and π-donor in complex 1 , though a longer U−C bond (2.666(3) Å) is observed. It implies that 1 is the first isolable mononuclear uranium(III) carbene complex. Moreover, these results suggest that CDPs are promising ligands to establish other low-valent f-block metal-carbon multiple bond complexes.     

Reduction of a Tetrafluoroterephthalonitrile‐β‐Cyclodextrin Polymer to Remove Anionic Micropollutants and Perfluorinated Alkyl Substances from Water

Organic micropollutants (MPs) are anthropogenic substances that contaminate water resources at trace concentrations. Many MPs, including per‐ and polyfluorinated alkyl substances (PFASs), have come under increased scrutiny because of their environmental persistence and association with various health problems. A β‐cyclodextrin polymer linked with tetrafluoroterephthalonitrile (TFN‐CDP) has high affinity for cationic and many neutral MPs from contaminated water because of anionic groups incorporated during the polymerization. But TFN‐CDP does not bind many anionic MPs strongly, including anionic PFASs. To address this shortcoming, we reduced the nitrile groups in TFN‐CDP to primary amines, which reverses its affinity towards charged MPs. TFN‐CDP exhibits adsorption distribution coefficients (log K_D values) of 2–3 for cationic MPs and ?0.5–1.5 for anionic MPs, whereas the reduced TFN‐CDP exhibits log K_D values of ?0.5–1.5 for cationic MPs and 2–4 for anionic MPs, with especially high affinity towards anionic PFASs. Kinetic studies of the removal of 10 anionic PFASs at environmentally relevant concentrations showed 80–98 % removal of all contaminants after 30 min and was superior to commercial granular activated carbon. These findings demonstrate the scope and tunability of CD‐based adsorbents derived from a single polymerization and the promise of novel adsorbents constructed from molecular receptors.     

Protective Effects of <em>Chlorella</em>-Derived Peptide Against UVC-Induced Cytotoxicity through Inhibition of Caspase-3 Activity and Reduction of the Expression of Phosphorylated FADD and Cleaved PARP-1 in Skin Fibroblasts

UVC irradiation induces oxidative stress and leads to cell death through an apoptotic pathway. This apoptosis is caused by activation of caspase-3 and formation of poly(ADP-ribose) polymerase-1 (PARP-1). In this study, the underlying mechanisms of Chlorella derived peptide (CDP) activity against UVC-induced cytotoxicity were investigated. Human skin fibroblasts were treated with CDP, vitamin C, or vitamin E after UVC irradiation for a total energy of 15 J/cm². After the UVC exposure, cell proliferation and caspase-3 activity were measured at 12, 24, 48, and 72 h later. Expression of phosphorylated FADD and cleaved PARP-1 were measured 16 h later. DNA damage (expressed as pyrimidine (6-4) pyrimidone photoproducts DNA concentration) and fragmentation assay were performed 24 h after the UVC exposure. Results showed that UVC irradiation induced cytotoxicity in all groups except those treated with CDP. The caspase-3 activity in CDP-treated cells was inhibited from 12 h onward. Expression of phosphorylated FADD and cleaved PARP-1 were also reduced in CDP-treated cells. Moreover, UVC-induced DNA damage and fragmentation were also prevented by the CDP treatment. This study shows that treatment of CDP provides protective effects against UVC-induced cytotoxicity through the inhibition of caspase-3 activity and the reduction of phosphorylated FADD and cleaved PARP-1 expression.     

Validated Chromatographic Methods for the Determination of Process Related Toxic Impurities in Pantoprazole Sodium

A GC–MS method for the simultaneous determination of two process related toxic impurities viz. 2-(chloromethyl)-3,4-dimethoxypyridine hydrochloride (CDP) and dimethyl sulfate (DMS) and RP-LC for the routine determination of CDP in pantoprazole sodium (PPS) are presented. In GC–MS, a temperature gradient program was performed on a capillary DB-624 column (60 m × 0.32 mm × 1.8 μm). LC analysis of CDP was done on a Novaflex C18 (250 × 4.6 mm, 5 μm) column using mobile phase containing buffer (0.02 M potassium dihydrogen phosphate and 0.0025 M di potassium hydrogen phosphate) and acetonitrile in 46:54 v/v ratio. The flow rate was 1.0 mL min^?1 and the elution was monitored at 220 nm. Both methods were validated as per International Conference on Harmonization (ICH) guidelines. GC–MS is able to quantitate up to 3.0 ppm of CDP and DMS whereas with RP-LC up to 9.0 ppm of CDP could be quantitated.     

From liquid to crystal via mechanochemical grinding: unique host–guest (HOF) cocrystal

Mechanochemical synthesis via grinding of trimesic acid (TA, C₉H₆O₆) and 4-chlorophenyl diphenyl phosphate (4CDP, C₁₈H₁₄ClO₄P) (liquid at room temperature) in a 1:1 ratio resulted in the formation of an inclusion type of cocrystal. The crystallization of this phase via slow evaporation at low temperature (276–277 K) from methanol resulted in a rare `stairstep morphology' during the process of crystal growth. This morphology was not observed after crystallization of the compound from other solvents like toluene, dichloromethane, acetone, hexane and isooctane, and hence this was characteristically observed in methanol only. The characterization from single-crystal X-ray diffraction revealed the formation of a cocrystal with five molecules of TA and two molecules of 4CDP in the asymmetric unit. The trimesic acid molecules form hydrogen-bonded dimers resulting in hexagonal rings, and these rings are stacked through π–π intermolecular interactions to make a hexagonal honeycomb-like structure. The phosphate molecules, 4CDP, were found to be trapped as guests in these hexagonal channels. The similarity in the packing of trimesic acid is compared in the cocrystal and the free acid quantitatively viaXpac analysis, which establishes the relationship of a `2D supramolecular construct' between them. This signifies a unique type of arrangement in which the voids created by the trimesic acid moiety do not undergo distortion by the inclusion of the guest molecules. The quantitative analysis of the intermolecular interactions using Hirshfeld surfaces and fingerprint plots deciphers the role of both strong O—H…O hydrogen bonds and weak intermolecular interactions in the crystal packing.     

Ligands Based on Phosphine-Stabilized Aluminum(I), Boron(I), and Carbon(0)

A systematic quantum chemical study of the bonding in d⁶-transition-metal complexes, containing phosphine-stabilized, main-group-element fragments, (R₃P)₂E, as ligands (E=AlH, BH, CH⁺, C), is reported. By using energy decomposition analysis, it is demonstrated that a strong M−E bond is accompanied by weak P−E bonds, and vice versa. Although the Al−M bond is, for example, found to be very strong, the weak Al−P bond suggests that the corresponding metal complexes will not be stable towards phosphine dissociation. The interaction energies for the boron(I)-based ligand are lower, but still higher than those for two-carbon-based ligands. For neutral ligands, electrostatic interactions are the dominating contributions to metal–ligand bonding, whereas for the cationic ligand a significant destabilization, with weak orbital and even weaker electrostatic metal–ligand interactions, is observed. Finally, for iron(II) complexes, it is demonstrated that different reactivity patterns are expected for the four donor groups: the experimentally observed reversible E−H reductive elimination of the borylene-based ligand (E=BH) exhibits significantly higher barriers for the protonated carbodiphosphorane (CDP) ligand (E=CH) and would proceed through different intermediates and transition states. For aluminum, such reaction pathways are not feasible (E=AlH). Moreover, it is demonstrated that the metal hydrido complexes with CDP ligands might not be stable towards reduction and isomerization to a protonated CDP ligand and a reduced metal center.     

The influence of partial substitution of phosphorus by arsenic in monoclinic CsH2PO4. X-ray single crystal,vibrational and phase transitions in the mixed CsH2(PO4)0.72(AsO4)0.28

Partial substitution of P by As, leading to the solid solution CsH₂(PO₄)_1−x(AsO₄)_x, with x=0.28 (abbreviated as CDAP) has been shown. The structural characteristics of the crystals were analyzed by means of X-ray diffraction, which revealed that the new title compound is nearly isomorphous with the monoclinic phase of CsH₂PO₄ (CDP). The structure was solved from 796 independent reflections with R₁=0.0292 and Rw₂=0.0702, refined with 59 parameters. The following results have been obtained: space group P2₁, a=4.9250(4) Å, b=6.4370(3) Å, c=7.9280(6) Å, β=107.316(3)°, V=239.94(3) Å³, Z=2 and ρ_cal=3.349 g cm⁻³. The hydrogen bonds are clearly distinguished in the electron density maps which display distributions corresponding to order of protons. The shorter bond (2.452(4) Å), links the phosphate–arsenate groups into chains running along the b-axis and the longer bond (2.531(3) Å), crosslinks the chains to form (001) layers. The Raman and infrared spectra of CDAP recorded at room temperature in the frequency ranges 15–1200 cm⁻¹ and 400–4000 cm⁻¹, respectively, confirm the presence of PO³⁻₄ and AsO³⁻₄ groups in the crystal. Differential scanning calorimetry traces show three phase transitions at 333, 449 and 490 K in this material, which are characterized by X-ray powder diffraction at high temperature.     

Synthesis of novel P-ketimine bidentate ferrocenyl ligands with central and planar chirality and comparsion in the catalytic activity between P-ketimine and P-aldimine

A series of novel ferrocenylphosphine-ketimine ligands 6 were prepared by reaction of (R,S_p)-PPFNH₂-R or (S,S_p)-PPFNH₂ with a variety of m-substituted acetophenones. A different catalytic activity was observed between ferrocenylphosphine-ketimine ligands and corresponding aldimine ligands. The efficiency and diastereomeric impact of these ferrocenylphosphine-ketimine ligands in Pd-catalyzed asymmetric allylic alkylation were first investigated, and higher enantioselectivity of over 98% e.e. with 95% yield was obtained by the use of ferrocenylphosphine-ketimine ligands. However, in Rh-catalyzed asymmetric hydrosilylation of aryl ketones, only 42% e.e. was obtained by the use of ferrocenylphosphine-ketimine ligands compared to 90% e.e. with the use of aldimine ligands.     

Substituted salen–Ru(II) complexes as catalysts in the asymmetric cyclopropanation of styrene by ethyl diazoacetate: the influence of substituents and achiral additives on activity and enantioselectivity

A series of alkyl-, halogen- and nitro-substituted salen ligands, 1, have been employed in the asymmetric cyclopropanation of styrene with ethyl diazoacetate by its ruthenium(II) complex with [RuCl₂(p-cymene)]₂ or RuCl₂(PPh₃)₃ as precursors. The introduction of appropriate electron withdrawing groups in the salen ligands benefited the enantioselectivity of the reaction. Some additives, including O-donor, N-donor and P-donor ligands, were added to the reaction to improve the enantioselectivity and activity, and e.e.s of up to 80% were achieved. In the salen/[RuCl₂(p-cymene)]₂ system, the (1R,2S)-isomer was obtained in 80.2% e.e. by using the salen ligand 1f derived from 3,5-dibrominated salicylaldehyde with Et₃N as additive. E.e.s of up to 81.3% for (1S,2R)-isomers were achieved by using the complex 2 synthesized from the nitro-substituted ligand 1m and RuCl₂(PPh₃)₃. A possible mechanism was also discussed.     

Two-photon spectroscopic behaviors and photodynamic effect on the BEL-7402 cancer cells of the new chlorophyll photosensitizer

The spectroscopic properties of a new chlorophyll derivate photosensitizer(CDP) are studied under the excitation wavelengths at 800 and 400 nm using femtosecond pulses from a Ti:sapphire laser.The damaging effect of CDP on the BEL-7402 cancer cells is also investigated upon two-photon illumination at 800 nm.The normalized fluorescence spectra of CDP in tetrahydrofuran(THF) show that two-photon and one-photon spectra have the same distributions and the same emission bands(675 nm).The life-times of two-and one-photon induced fluorescence of this molecule are of the order of 5.0 ns.By comparing the data it is shown that there is some difference between the two lifetimes,but the differ-ence is less than one nanosecond.The two-photon absorption cross section of the molecule is also measured at 800 nm and estimated as about σ′2 ≈ 31.5×10-50 cm4·s·photon-1.The results of two-photon photodynamic therapy(TPPDT) tests show that CDP can kill all of the tested cancer cells according to the usual Eosine assessment.Our results indicate that the two-photon-induced photophysical,photo-chemical and photosensitizing processes of CDP may be basically similar to those of one-photon ex-citation.These behaviors of the sample suggest that one may find other possible methods to estimate some photosensitizers' effects in details such as their distribution in cells and the reactive targets of the sub-cellular parts of some tumor cells via two-photon excitation techniques.     

Substrate specificity of the CYC2 enzyme from Kitasatospora griseola: production of sclarene, biformene, and novel bicyclic diterpenes by the enzymatic reactions of labdane- and halimane-type diterpene diphosphates

The enzymatic reaction of copalyl diphosphate (CDP), ent-CDP, syn-CDP, and tuberculosinyl diphosphate with the CYC2 enzyme from Kitasatospora griseola afforded sclarene, biformene, and novel diterpenes having a buta-1,3-diene moiety in the side chain. The substrate specificity of the CYC2 is discussed.     

Molecular weight between entanglements for linear d-glucans

Dynamic viscoelasticity measurements were carried out for concentrated solutions of linear d-glucans in BmimCl to examine the effect of the linkage between repeating units of glucose on the rheological properties. The values of molecular weight between entanglements (M _e) were determined for four d-glucans: curdlan, pullulan, cellulose, and amylose. From the concentration dependence of M _e, the value of M _e in the molten state (M _e,melt) for each d-glucan was estimated as a material constant. The order of M _e,melt became cellulose?<?pullulan?<?curdlan?<?amylose, indicating that the linkage is actually influential in M _e,melt for the linear d-glucans. The relationship between M _e,melt and the molecular structure of the d-glucans were discussed assuming that the values of M _e,melt for the d-glucans primarily reflect the chain stiffness such as the characteristic ratio C _∞ on the analogy of synthetic polymers. Although the trend was not so clear, it was shown that N _unit is a decreasing function of C _∞ .     

Crystallographic shear in the Nb2O5WO3 and Ta2O5WO3 systems

Crystallographic shear (CS) phases occurring in the Nb₂O₅WO₃ and Ta₂O₅WO₃ systems near to WO₃ were characterized by X-ray diffraction and high-resolution transmission electron microscopy. The Nb₂O₅WO₃ samples were heated at 1600K. They contained ordered {104} and {001} CS planes and wavy CS which were composed of intergrowths of {104} and {001} CS segments. The composition range over which the {104} CS series extended was from (Nb,W)O_2.954 i.e., (Nb,W)₆₅O₁₉₂, to (Nb,W)O_2.942, i.e., (Nb,W)₅₂O₁₅₃. The composition range over which the {001} CS series extended was from (Nb,W)O_2.9375, i.e., (Nb,W)₁₆O₄₇ to (Nb,W)O_2.875, i.e., (Nb,W)₈O₂₃. The Ta₂O₅WO₃ samples were prepared at 1593, 1623, and 1672K. At lower temperatures ordered {103} CS phases were found, with a composition range extending between (Ta,W)O_2.960, i.e., (Ta,W)₅₀O₁₄₈, to (Ta,W)O_2.944, i.e., (Ta,W)₃₆O₁₀₆. At 1673K ordered {103} CS phases occurred, as did wavy CS composed of intergrowths of {103} and {104} CS segments.     

Synthesis,biochemical evaluation and computational simulations of new cytochrome bc1 complex inhibitors based on N-(4-aryloxyphenyl) phthalimides

A series of N-(4-aryloxyphenyl)phthalimides were synthesized and identified as new inhibitors of the cytochrome bc1 complex. Furthermore, results obtained from computational simulations indicated that 3e' should bind to the Q_o site of the bc1 complex.     

Thermal transformations in nanosized MoO3 layers

The degree of the transformation of MoO₃ films (d= 8–130 nm) increased as the duration (1–140 min) and temperature (373–573 K) of thermal treatment grew and as the film thickness decreased under atmospheric conditions. The thermal treatment of MoO₃ films decreased the optical density at λ = 350 nm and caused the appearance of an absorption maximum at λ = 870 nm. A mechanism of thermal transformations of MoO₃ was suggested. The mechanism included the formation of the [(V _a)⁺⁺e] center during the preparation and thermal treatment of MoO₃ films and thermal electron transition from the valence band to the [(V _a)⁺⁺e] center level with the formation of the [e(V_a)⁺⁺e] center.     

Theoretical study of the electronic transition moment for the d 3IIga 3IIu band system of the C2 molecule

Large scale ab initio SCF and CI calculations are employed to study the potential curves for the d ³II_g, a ³II_u and X¹Σ⁺_g states of the C₂ radical. The electronic transition moment R_e′e″ for the Swan bands (d ³II_ga ³II_u) is calculated in various AO and MO basis sets as a function of the internuclear CC distance. The form of the Σ|R_e′e″|² curve is in very good agreement with that obtained recently from measurements of Danylewych and Nicholls and Tatarczyk et al.; the calculated value for Σ|R_e′e″² at 2.44 bohr is found to be 5.2 au² compared to the most recent experimental values of |R_e(r_oo)|² = 3.57 au² of Tatarczyk et al.     

[(CrGe9)Cr2(CO)13]4−: A disubstituted case of ten-vertex closo cluster with spherical aromaticity

We report the first disubstituted hetero-ten-vertex closo cluster [(CrGe₉)Cr₂(CO)₁₃]^4? with three adjacent Cr(CO)_n units adopting both η⁵ and η¹ coordination modes, which was synthesized through the reaction of “KGe_1.67” with (MeCN)₃Cr(CO)₃ and Cr(CO)₆ in ethylenediamine (en) solution. In contrast to the η¹-Cr atoms forming localized two-center two-elelctron (2c-2e) Cr-Ge bonds, the hetero atom η⁵-Cr exhibits versatile bonding mechanisms including three 5c-2e and five 8c-2e delocalized bonds which account for Hückel aromaticity. Intricate multi-center bonding patterns delineate the multiple local σ-aromatic characters of the title cluster displaying explicit spherical aromaticity.     

On the reaction kinetics of electrogenerated superoxide ion with aryl benzoates

The reactions between electrogenerated superoxide ion O₂^? and two benzoate esters in N, N-dimethylformamide containing tetrabutylammonium perchlorate have been investigated. By using cyclic voltammetric techniques an e.c.e. type mechanism was found to be operative; this was confirmed by controlled potential electrolysis experiments. Secondorder rate constants for nucleophilic displacement by O₂^? on p-chlorophenyl benzoate and phenyl benzoate were estimated to be 25.0±5 and 3.0±0.3 M^?1 s^?1 respectively by fitting potential step reduction data to i_k/i_d vs. log kt working curves.