Low wavenumber Raman bands (300−50 cm−1) and isotopic effects of lithium acetate dihydrate

The Raman spectra in the 300−50 cm⁻¹ region were investigated for eight isotopically substituted lithium acetate dihydrates. ″LiCX₃′CO₂…2X₂″O. The observed spectral data are discussed taking the isotopic effects on the fundamental modes of vibration into consideration.     

An In-Situ Cyanidation Strategy To Access Tetracyanodiacenaphthoanthracene Diimides with High Electron Mobilities Exceeding 10 cm2 V−1 s−1

A family of novel highly π-extended tetracyano-substituted acene diimides, named as tetracyanodiacenaphthoanthracene diimides (TCDADIs), have been synthesized using a facile four-fold Knoevenagel condensation strategy. Unlike conventional cyano substitution reactions, our approach enables access to a large π-conjugated backbone with the in-situ formation of four cyano substitutents at room temperature while avoiding extra cyano-functionalization reactions. TCDADIs decorated with different N-alkyl substituents present good solubility, near-coplanar backbones, good crystallinity, and low-lying lowest unoccupied molecular orbital energies of −4.33 eV, all of which contribute to desirable electron-transport performance when applied in organic field-effect transistors (OFET). The highest electron mobility of an OFET based on a 2-hexyldecyl-substituted TCDADI single crystal reaches 12.6 cm² V⁻¹ s⁻¹, which is not only among the highest values for the reported n-type organic semiconductor materials (OSMs) but also exceeds that of most n-type OSMs decorated with imide units.     

The Raman spectrum of ethane from 600 to 6500 cm−1 stokes shifts

The vibrational Raman Stokes spectrum of ethan (C₂H₆) has been recorded from 600 to 6500 cm⁻¹ using the powerful focused radiation of a free running Ar-ion laser. Measurements in bulk and in jet were performed in an intracavity arrangement. The present analysis is concentrated on totally, symmetric transitions. Numerous Q branches of overtones and binary combination tones appeared in the spectrum. All first overtones of both the degenerate and non-degenerate modes have been observed. Several multiple combination tones have also been identified. Some hot bands due to transitions starting from the thermally excited v₄ torsional level appeared as satellite Q branches. From the measured band origins the anharmonic shifts are determined and a table with the anharmonicity constants is constructed. The occurrence of a few very strong Fermi resonances enhancing the intensity of otherwise weak bands has been observed. A comparative study of some overtone Raman spectra of three substituted ethanes (CH₃CF₃, CH₃, CH₃SiH₃, CH₃CD₃) has been undertaken. The existence of a strong interaction between the CH₃ symmetric stretching modes and the overtones of the asymmetric deformation modes appears to be characteristic only for the CH₃CH₃ and CH₃CD₃ molecules.     

Light-induced FTIR difference spectroscopy of photosynthetic charge separation between 9000 and 250 cm−1

The light-induced FTIR difference spectrum corresponding to photosynthetic charge separation between the dimeric bacteriochlorophyll primary donor (P) and the quinone Q_A in the reaction center of the photosynthetic bacterium Rhodobacter sphaeroides has been measured in the frequency range between 9000 and 250 cm⁻¹ using a DTGS detector. Upon extensive signal averaging, the noise level is reduced below 2×10⁻⁵ absorbance unit. The positive bands of the difference spectrum contribute much more than the negative ones over the whole frequency range investigated. In the region below 650 cm⁻¹, a number of bands of small amplitude are observed for the first time. The presence of a tail extending between 6000 and 3600 cm⁻¹ on the high-energy side of the electronic transition of P⁺ peaking at ≈2600 cm⁻¹ [J. Breton, E. Nabedryk, W.W. Parson, Biochemistry, 31 (1992) 7503–7510] is confirmed.     

Etude vibrationnelle des chlorhydrates de methyl-1 triazoliums-1,2,4 dans la region 1600-200 cm−1

The infrared and Raman spectra of chlorhydrates of 1-methyl 1,2,4-triazolium 1-methyl C-halogeno 1,2,4-triazolium have been obtained in the 1600-200 cm⁻¹ range. An assignment of the fundamental vibrations is proposed and the effect of protonation is discussed.     

Catalytic Chemistry Derived Artificial Solid Electrolyte Interphase for Stable Lithium Metal Anodes Working at 20 mA cm−2 and 20 mAh cm−2

A stable solid electrolyte interphase (SEI) layer is crucial for lithium metal anode (LMA) to survive in long-term cycling. However, chaotic structures and chemical inhomogeneity of natural SEI make LMA suffering from exasperating dendrite growth and severe electrode pulverization, which hinder the practical application of LMAs. Here, we design a catalyst-derived artificial SEI layer with an ordered polyamide-lithium hydroxide (PA-LiOH) bi-phase structure to modulate ion transport and enable dendrite-free Li deposition. The PA-LiOH layer can substantially suppress the volume changes of LMA during Li plating/stripping cycles, as well as alleviate the parasitic reactions between LMA and electrolyte. The optimized LMAs demonstrate excellent stability in Li plating/stripping cycles for over 1000 hours at an ultra-high current density of 20 mA cm⁻² in Li||Li symmetric cells. A high coulombic efficiency up to 99.2 % in Li half cells in additive-free electrolytes is achieved even after 500 cycles at a current density of 1 mA cm⁻² with a capacity of 1 mAh cm⁻².     

Infrared spectra of cyclohexane-1,3-dione derivatives in the region of 1750–1550 cm−1

Russian Chemical Bulletin -     

Low-frequency (20–400 cm−1) vibrational spectra of N-methylacetamide in the liquid state

Low-frequency Raman spectra (20–400 cm⁻¹) of liquid N-methylacetamide were studied. The experimental data were directly transformed into the R(v) representation. This spectrum was compared with the far infrared spectrum. Temperatures from 30 to 165 °C were investigated. A low-frequency band around 100 cm⁻¹ is assigned to a mode involving atoms in intermolecular hydrogen bonds. This assignment is qualitatively supported by the observed spectrum of Nd-methylacetamide.     

A spectroscopic investigation of the carrageenans and agar in the 1500-100 cm−1 spectral range

Fourier transform infrared (FTIR) and Raman spectra in the 1600-100 cm⁻¹ range have been employed in a structural analysis of biopolymers of the polygalactane type. In spite of the complexity of the spectra in this region, precise assignments have been made, first on the basis of previously calculated frequencies of the basic unit (d-galactose) and secondly by comparing the spectra of kappa-, iota-, and lambda-carrageenans, as well as agar and appropriate disaccharides. The results of this work provide confirmation of previous assignments of IR absorptions at 930, 820, 805 and 845 cm ⁻¹ and the interpretation of several other bands, notably those due to bending vibrations of the glycosidic linkages and those between 1040 and 1010 cm⁻¹. The latter are associated with the OSO symmetrical stretch. Assignments are also presented for the 700-100 cm⁻¹ region, on which there are no previous reports. The present analysis may provide a basis for further studies of the conformational changes accompanying gelation, a process which is different from one polygalactane to another.     

A full vibrational assignment (4000-50 cm−1) of 1, 10-phenanthroline and its perdeuterated analogue

Full infrared and Raman vibrational assignments (4000-50 cm⁻¹) of 1,10-phenanthroline are presented and full infrared assignments (4000-50 cm⁻¹) of 1,10-phenanthroline-d₈ are given. Four fundamentals are newly reported for 1,10-phenanthroline and several changes are recommended to earlier assignments for this compound. The assignments of the fully deuterated analogue are newly reported.     

New Oxyhalide Solid Electrolytes with High Lithium Ionic Conductivity >10 mS cm−1 for All-Solid-State Batteries

All-solid-state batteries (ASSBs) with inorganic solid electrolytes (SEs) have attracted significant interest as next-generation energy storage. Halides such as Li₃YCl₆ are promising candidates for SE because they combine high oxidation stability and deformability. However, the ionic conductivities of halide SEs are not as high as those of other SEs, especially sulfides. Here, we discover new lithium-metal-oxy-halide materials, LiMOCl₄ (M=Nb, Ta). They exhibit extremely high ionic conductivities of 10.4 mS cm⁻¹ for M=Nb and 12.4 mS cm⁻¹ for M=Ta, respectively, even in cold-pressed powder forms at room temperature, which are comparable to or surpass those of organic liquid electrolytes used in lithium-ion batteries. Bulk-type ASSB cells using the oxyhalides as the cathode SE demonstrate an outstanding rate capability with a capacity retention of 80 % at 5 C/0.1 C. We believe that the proposed oxyhalides are promising SE candidates for the practical applications of ASSBs.     

From Bq cm−3 to Bq cm−2 (and conversely)—part 2: useful dataset to apply the conversion to decommissioning operations

Journal of Radioanalytical and Nuclear Chemistry - A large set of key parameters is provided to use in decommissioning operations, the conversion method fully described in the companion paper...     

ATR-FT-IR spectroscopy in the region of 550–230 cm−1 for identification of inorganic pigments

A comprehensive study of ATR-FT-IR spectra of 40 inorganic pigments of different colours widely used in historical paintings has been carried out in the low wave number spectral range (550–230 cm^?1). The infrared spectra were recorded from mixtures of pigment and linseed oil. It is demonstrated that this spectral range – essentially devoid of absorption peaks of the common binder materials – can be well used for identification of inorganic pigments in paint samples thereby markedly extending the possibilities of pigment identification/confirmation by ATR-IR spectroscopy into the realm of pigments having no absorptions in the mid-IR region. In some cases the method can be used alone for pigment identification and in many cases it provides useful additional evidence for pigment identification using other instrumental techniques (electron microprobe analysis, XRF, optical microscopy). Together with earlier work this study provides a comprehensive overview of the pigment identification possibilities using ATR-FT-IR as well as a collection of reference spectra and is expected to be a useful reference for conservation practitioners.     

Intercalated hybrid of kaolinite with KH2PO4 showing high ionic conductivity (∼10−4 S cm−1) at room temperature

In this paper, we present the study of preparation and ionic conductance for an intercalated hybrid of kaolinite with potassium dihydrogen. The intercalation efficiency is high up to ca. 90%. The intercalated hybrid has been characterized by powder X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis. The ionic conductivity (σ) of the hybrid material is strongly dependent on the moisture in the environment, with σ = 8.4 × 10⁻¹⁰ S cm⁻¹ at 293 K and gradually increases to 7.16 × 10⁻⁹ S cm⁻¹ under N₂ atmosphere (anhydrous environment) at 353 K as well as an activation energy of E_a = 0.618 e V, whereas σ = 2.19 × 10⁻⁴ S cm⁻¹ at 100% relative humidity and 293 K with E_a = 0.44 eV. The mechanism that the moisture affects the ionic conductance of the intercalated hybrid is further discussed.     

Preparation and properties of the systems Co1−xRhxS2, Co1−xRuxS2, and Rh1−xRuxS2

Members of the systems Co_1−xRh_xS₂ (0 ≤ x ≤ 0.6) were prepared, and their crystallographic and magnetic properties studied. The observed ferromagnetic moments for compositions where x ≤ 0.2 indicate a ferromagnetic alignment between Co(3d⁷) and Rh(4d⁷) electrons. This is the first observation of localized behavior of 4d electrons in the pyrite structure. Members of the systems Co_1−xRu_xS₂ (0 ≤ x ≤ 1) and Rh_1−xRu_xS₂ (0.5 ≤ x ≤ 1) were also prepared and their crystallographic and magnetic properties studied. From comparison with the Co_1−xRh_xS₂ system, it appears that the 4d electrons of Rh(4d⁷) are localized in the presence of Co(3d⁷) but are delocalized in the presence of Ru(4d⁶). The magnetic susceptibility of the Co_1−xRu_xS₂ system is sensitive to the homogeneity of the products and indicates that Ru(4d⁶) behaves as a diamagnetic ion.     

Synthesis of Novel Organosiliconsulfur-Containing Tetrasubstituted Imidazoles Sonocatalyzed by LaxSr1−xFeyCo1−yO3 Nanoperovskites

Abstract

The one-pot synthesis of tetrasubstituted imidazoles by use of a series of La_xSr_1 ? xFe_yCo_1 ? yO₃ perovskites as catalysts is described. The La_0.8Sr_0.2Fe_0.34Co_0.66O₃ nanocatalyst had the greatest activity in the heterogeneous cyclocondensation of an aldehyde, benzil, ammonium acetate, and a primary aromatic amine in water under ultrasonic irradiation. Some of the derivatives generated during this work were utilized as substrates for the synthesis in good yields of novel multifunctional tetrasubstituted imidazoles with Me₃Si, C=S, and SH groups, via nucleophilic attack of tris(trimethylsilyl)methyllithium (TsiLi) at the carbon of carbon disulphide.