Intense Absorption Band Research Articles

Exploring molecule-surface interactions of urania via IR spectroscopy and density functional theory.

Within the framework of surface-adsorbate interactions relevant to chemical reactions of spent nuclear fuel, the study of actinide oxide systems remains one of the most challenging tasks at both the experimental and computational levels. Consequently, our understanding of the effect of their unique electronic configurations on surface reactions lags behind that of d-block oxides. To investigate the surface properties of this system, we present the first infrared spectroscopy analysis of carbon monoxide (CO) interaction with a monocrystalline actinide oxide, UO2(111). Using a monocrystalline form largely avoids issues related to super-stoichiometries (UO2+x) and makes the experimental data suitable for further theoretical studies. Our findings reveal that CO adsorbs molecularly and shows a pronounced blue shift of the vibrational frequency to 2160 cm-1 relative to the gas-phase value. Interpreted through density functional theory (DFT) at different levels of computation, results indicate that to accurately describe the interaction between the CO molecule and the surface, it is essential to consider hybrid functionals, the non-collinearity of uranium's local magnetic moments, and spin-orbit coupling. Moreover, an intense IR absorption band at 978 cm-1 emerged upon CO adsorption, tentatively attributed to the frequency shift of the O-U-O asymmetric stretch of the UO2(111) surface in the presence of adsorbed oxygen. This new band, together with the observation of the importance of the relativistic effects in determining the nature of the chemical bonding of CO, is poised to broaden our understanding of actinide surface reactions.

THE INTERSUBBAND OPTICAL ABSORPTION COEFFICIENT OF THE QD WITH ACCEPTOR IMPURITY UNDER APPLIED ELECTRIC FIELD

In this work, a spherical quantum dot (QD) under the influence of an external electric field is investigated. A multi-band model of the valence band is applied. The influence of off-center acceptor impurity, electric field and QD size dispersion on the absorption coefficient during intersubband transitions between hole states has been analyzed. The results show that an electric field combined with an off-center impurity induces the appearance of two distinct absorption bands corresponding to different magnetic quantum numbers. The intensity of absorption bands depends on the direction and strength of the electric field, and significant differences are observed between fields of opposite polarity. It is important to note that there is a critical field strength that restores the degeneracy of the energy levels, narrowing the broadband absorption tail for systems with small or large dispersion sizes. This research aims to improve the understanding and optimization of the optical properties of nanomaterials.

Synthesis and structural characterization of new complexes based on silver nanoparticles, diphenylcarbazide, and cetyltrimethylammonium bromide

In this work, the synthesis of new complexes based on silver nanoparticles (AgNP), diphenylcarbazide reagent (DPC), and cetyltrimethylammonium bromide (CTAB) was carried out, and the optimal conditions for their production were determined. The structures of the synthesized binary DPC+Ag and ternary DPC+Ag+CTAB complexes were studied using X-ray diffraction (XRD), infrared (IR), and ultraviolet (UV) spectroscopy. From the UV analysis, it was observed that the maximum peaks of the DPC reagent are found at wavelengths of 235 nm, 262 nm, 308 nm, and 345 nm, corresponding to the π-π* transition of the C-C bond and the n-π* transition between the C=N groups. Due to the surface plasmon resonance of the binary complex, new peaks in the absorption spectra were identified at wavelengths of 248 nm, 288 nm, 315 nm, and 355 nm. In the ternary complex, peaks in the absorption band were observed at wavelengths of 305 nm and 348 nm. The spectroscopic properties of DFC and its binary and ternary complexes were investigated through IR analyses. The aromatic C-H bonds of the phenyl group appear in the range of 3000-3100 cm⁻¹, while the C=C bonds of the phenyl group appear around 1500-1600 cm⁻¹. The peaks corresponding to the carbonyl (C=O) bond of the carbazide group are found in the range of 1650-1700 cm⁻¹, and the peaks related to the N-H groups appear around 1500-1600 cm⁻¹. The interaction of DFC with AgNPs was examined by analyzing shifts and changes in intensity of the IR spectroscopy absorption bands.

Enhancing Near‐Infrared Absorption in Osmium(II) Complexes Under the Cumulative Influence of Terpyridine Ligand and Anions: Combined Experimental and DFT/TD‐DFT Investigation

AbstractThis work presents synthesis, characterization, and thorough examination on the photophysical and electrochemical behaviours of a new class of homo‐ and heteroleptic Os(II)‐terpyridine complexes. The compounds exhibit intense singlet metal‐to‐ligand charge‐transfer (1MLCT) bands in the visible region (490–500 nm) and weak and broad spin‐forbidden bands in the spectral window of 670–680 nm due to singlet ground state (1GS) to 3MLCT state transition, facilitated by spin‐orbit coupling. The complexes exhibit strong luminescence within 730–750 nm at room temperature having lifetimes in the domain of 101–158 ns, depending upon solvents. Taking advantage of active methylene protons, anion‐induced modulation of spectral and electrochemical characteristics of the complexes has been convincingly demonstrated via different optical channels and spectroscopic tools as well as by cyclic voltammetry. The augmentation in absorption spectral characteristics is quite remarkable in presence of F− and intense absorption bands spanning across the entire visible region and stretching up to NIR domain is achieved. The mode of complex‐anion interplay was elucidated via 1H, 31P{1H} and 19F NMR spectroscopy as well as by computational investigations using DFT and TD‐DFT methods. The complexes also act as molecular sensors and switches that can function in visible and NIR domains upon alternate addition of anion and acid.

Vitamin B6 Appended Polypyridyl Co(III) Complexes for Photo-Triggered Antibacterial Activity.

Three novel polypyridyl-Co(III)-vitamin B6 complexes viz., [Co(CF3-phtpy)(SBVB6)]Cl (Co1), [Co(anthracene-tpy)(SBVB6)]Cl (Co2), [Co(NMe2-phtpy)(SBVB6)]Cl (Co3), where 4'-(4-(trifluoromethyl)phenyl)-2,2':6',2''-terpyridine=CF3-phtpy, 4'-(anthracen-9-yl)-2,2':6',2''-terpyridine=anthracene-tpy;, 4-([2,2':6',2''-terpyridin]-4'-yl)-N,N-dimethylaniline=NMe2-phtpy, (E)-5-(hydroxymethyl)-4-(((2-hydroxyphenyl)imino)methyl)-2-methylpyridin-3-ol=H2SBVB6 were successfully developed for aPDT (antibacterial photodynamic therapy) applications. Co1-Co3 exhibited an intense absorption band at ca. 435-485 nm, which is attributed to ligand-to-metal charge transfer and was beneficial for antibacterial photodynamic therapy. The distorted octahedral geometry of the complexes with CoIIIN4O2 core was evident from the DFT study. The visible light absorption ability and good photo-stability of Co1-Co3 made them good photosensitizers for aPDT. Co1-Co3 displayed significant antibacterial responses against gram-positive (S. aureus) and gram-negative (E. coli) bacteria upon light exposure (10 J cm-2 , 400-700 nm) and showed MIC values between 0.01-0.005 μg mL-1. The aPDT activities of these complexes were due to their ability to damage bacterial cell membranes via ROS generation. Overall, this study shows the photo-triggered ROS-mediated bacteria-killing potential of Co(III) complexes.

Annealing effect of Ca3TaGa3Si2O14 catangasite crystals on their optical activity

The spectral dependences of transmission and absorption in the wavelength range of 200–2500 nm were measured for Ca3TaGa3Si2O14 crystals cut perpendicular to the optical axis in the initial state (without annealing) and after isothermal annealing in vacuum and in air. It was found that annealing in vacuum leads to a decrease, and annealing in air leads to an increase in the intensity of absorption bands. A spectrophotometric method for measuring and calculating the specific rotation angle ρ of the plane of polarization of light in gyrotropic crystals from the transmission coefficient spectra at different angles between the polarizer and the analyzer is considered. The transmission spectra were normalized in order to eliminate shifts in the spectra associated with measurement features. Spectral dependences of the values of ρ for all three samples, which are approximated by the extended Drude formula, are obtained; the influence of the annealing atmosphere on the values of the coefficients of this formula is established.

СИНТЕЗ ТА АНТИОКСИДАНТНА АКТИВНІСТЬ 2-МЕТИЛ-5-ХЛОРО-2,3-ДИГІДРОІМІДАЗО[2,1-b][1,3]ТІАЗОЛ-6-КАРБАЛЬДЕГІДУ

Imidazothiazoles annelated to the b face have been of particular interest to researchers in recent decades due to their powerful medical and biological potential. Antioxidant therapy of diseases associated with oxidative stress is one of the important areas of modern medicine. That is why this work is devoted to the synthesis of 2-methyl-5-chloro-2,3-dihydroimidazo[2,1-b][1,3]thiazole-6-carbaldehyde and the evaluation of its antioxidant potential. Synthetically available 2-methyl-2,3-dihydroimidazo[2,1-b][1,3]thiazol-5(6H)-one was used as a substrate. The presence of an activated methylene group in its structure makes it very attractive for further structural modification by pharmacoform groups and construction of biologically active compounds. It was found that 2-methylimidazothiazole undergoes a Vilsmeier-Haack reaction during heating with a DMF/POCl3 complex to form a 6-formyl-5-chloro derivative with a yield of 25%. The composition and structure of this chloraldehyde synthesized for the first time was unambiguously confirmed by a set of physicochemical analysis, including elemental analysis, chromato-mass, IR and NMR spectra. Specifically, IR spectrum contains an intense absorption band of valence vibrations of the С=О group at 1684 cm–1. The 1H NMR spectrum is characterized by a formyl group singlet at 9.72 ppm, and the signal of the corresponding carbon atom in the 13C NMR spectrum is recorded at 182.2 ppm. The fact of aromatization of the imidazole ring is confirmed by the shift of the signals of C5 and C6 atoms to the region of 139.4 ppm and 123.2 ppm, respectively. The antioxidant activity was assessed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical inhibition method. Initially, it was experimentally confirmed that the rate of inhibition of radicals by the synthesized compound at a concentration of 5 mM is 54.1%. The next stage of the study showed that the IC50 data is 1.669 mM, vs IC50 = 0.097 mM for ascorbic acid. Therefore, 2-methyl-5-chloro-2,3-dihydroimidazo[2,1-b][1,3]thiazole-6-carbaldehyde is of interest for advanced pharmacological studies and design of promising synthetic antioxidants.

Spectral and Luminescence Study of Er3+ Doped Phosphate Glasses for the Development of 1.5 µm Broadband Amplifier

Ytterbium zinc lithium lead alumino antimony borophosphate glasses containing Er3+ in (25-x)P2O5: 10ZnO: 10Li2O: 10PbO: 10Al2O3: 10Sb2O3: 10Y2O3: 15B2O3: Er2O3 (where x=1, 1.5,2 mol %) have been prepared by melt-quenching method. The amorphous nature of the glasses was confirmed by x-ray diffraction studies. Optical absorption, excitation Spectrum and fluorescence spectra were recorded at room temperature for all glass samples. Judd-Ofelt intensity parameters Ωλ (λ=2, 4, 6) are evaluated from the intensities of various absorption bands of optical absorption spectra. Using these intensity parameters various radiative properties like spontaneous emission probability, branching ratio, radiative life time and stimulated emission cross– section of various emission lines have been evaluated.

Photoluminescence and Raman analysis of Nd3+ doped in Ytterbium Zinc Lithium Sodium Barium Calcium Aluminophosphate glasses

Glass of the system:(30-x)P2O5:10ZnO:10Li2O:10Na2O:10BaO:10CaO:10Al2O3: 10Y2O3: x Nd2O3. (where x=1, 1.5,2 mol %) have been prepared by melt-quenching method. (where x=1,1.5 and 2 mol%) have been prepared by melt-quenching technique. The amorphous nature of the prepared glass samples was confirmed by X-ray diffraction. Optical absorption, Excitation, fluorescence and Raman spectra have been recorded at room temperature for all glass samples. Judd-Ofelt intensity parameters Ωλ (λ=2, 4 and 6) are evaluated from the intensities of various absorption bands of optical absorption spectra. Using these intensity parameters various radiative properties like spontaneous emission probability, branching ratio, radiative life time and stimulated emission cross–section of various emission lines have been evaluated

Spectral, Thermal and Upconversion Properties of Dy3+ Doped Borotellurite Glasses with Large Stability Parameter

Glass sample of yttrium zinc lithium lead sodium alumino borotellurite (25-x) TeO2:10ZnO:10Li2O:10PbO:10Na2O:10Al2O3:10Y2O3:15B2O3:xDy2O3. (wherex=1,1.5 and 2 mol%) have been prepared by melt-quenching technique. The amorphous nature of the prepared glass samples was confirmed by X-ray diffraction. Optical absorption, excitation spectrum and fluorescence spectra were recorded at room temperature for all glass samples. Judd-Ofelt intensity parameters Ωλ (λ=2, 4 and 6) are evaluated from the intensities of various absorption bands of optical absorption spectra. Using these intensity parameters various radiative properties like spontaneous emission probability, branching ratio, radiative life time and stimulated emission cross–section of various emission lines have been evaluated

Synthesis, Structure, and Properties of Nontrivial Iridium(III) Complexes Based on Anthracene-Decorated Benzimidazole Ligand.

Reactions of iridium trichloride hydrate with bulky 2-(9-anthracenyl)-1-phenyl-benzimidazole (anbi) in the presence of N-donor ligands afforded a number of unique noncyclometalated complexes, while attempts to prepare a common μ-chloro-bridged bis-cyclometalated dimer systematically gave a monocyclometalated complex cis-[Ir(C,N-anbi)(N-anbi)Cl2] instead. The obtained complexes were characterized by 1H NMR, high-resolution mass spectrometry, single-crystal and powder X-ray diffraction, UV-vis spectroscopy, and cyclic voltammetry. The noncyclometalated complexes fac-[Ir(N-anbi)(N^N)Cl3)], where N^N are 4,4'-disubstituted 2,2'-bipyridines, are octahedral and contain the anthracene and 2,2'-bipyridine units in a close cofacial arrangement. These complexes were found to be exceptionally inert to the chloride ligand exchange even in the presence of silver triflate, forming a rare trinuclear Ir-μ-Cl3-Ag-μ-Cl3-Ir structure instead. In the monocyclometalated complex, the Ir(III) ion is pentacoordinated in a rare square-pyramidal geometry, where the bulky anthracene fragment is involved in the steric shielding of the metal center. This is in line with the results of gas-phase density functional theory calculations, demonstrating that the experimentally observed structure is energetically most preferable. The monocyclometalated complex is deeply colored due to intense charge-transfer absorption bands in the range 450-650 nm with ε = 2000-5000 M-1 cm-1, superior to the noncyclometalated complexes. The synthesis, structures, and properties of the new complexes are discussed in the context of the related mono-, bis-, and noncyclometalated iridium(III) compounds.

Green-light wavelength-selective organic solar cells: module fabrication and crop evaluation towards agrivoltaics

Green-light wavelength-selective organic solar cells (GLWS-OSCs) pioneer novel agrivoltaics in greenhouses via transforming solar energy in the green-light region to electricity while simultaneously growing crops by utilizing the transmitted blue and red lights. However, the development of GLWS-OSCs has been stymied due to the limited availability of donors and acceptors. Herein, we investigate the combination of a cost-effective poly(3-hexylthiophene) (P3HT) donor with a fluorinated-naphthobisthiadiazole-based non-fullerene acceptor (FNTz-FA) for GLWS-OSC application. FNTz-FA shows an intense absorption band between 500 and 600 nm and a high level of chemical stability. OSCs based on P3HT and FNTz-FA with an inverted configuration are optimized to show high green-light wavelength-selective absorption and power conversion efficiency in the green-light region. Furthermore, large-scale device fabrication has been considered, leading to the development of 100 and 400 cm2 scale OSC modules. These modules showed sustained solar cell performance after 180 days. Photosynthetic rate measurements indicate that transmissions by the P3HT:FNTz-FA film show a non-obstructing nature and the advantage of green-light wavelength-selectivity in crop growth. Preliminary investigations on the growth of tomatoes have shown the potential of P3HT:FNTz-FA-based OSCs for agrivoltaics. These results demonstrate that GLWS-OSCs are a valid candidate to realize agrivoltaics in greenhouses for an effective utilization of solar energy.

Effect of Surface Contamination on Near-Infrared Spectra of Biodegradable Plastics.

Proper waste sorting is crucial for biodegradable plastics (BDPs) recycling, whose global production is increasing dynamically. BDPs can be sorted using near-infrared (NIR) sorting, but little research is available about the effect of surface contamination on their NIR spectrum, which affects their sortability. As BDPs are often heavily contaminated with food waste, understanding the effect of surface contamination is necessary. This paper reports on a study on the influence of artificially induced surface contamination using food waste and contamination from packaging waste, biowaste, and residual waste on the BDP spectra. In artificially contaminated samples, the absorption bands (ADs) changed due to the presence of moisture (1352-1424 nm) and fatty acids (1223 nm). In real-world contaminated samples, biowaste samples were most affected by contamination followed by residual waste, both having altered ADs at 1352-1424 nm (moisture). The packaging waste-contaminated sample spectra closely followed those of clean and washed samples, with a change in the intensity of ADs. Accordingly, two approaches could be followed in sorting: (i) affected wavelength ranges could be omitted, or (ii) contaminated samples could be used for optimizing the NIR database. Thus, surface contamination affected the spectra, and knowing the wavelength ranges containing this effect could be used to optimize the NIR database and improve BDP sorting.

Hydrogen bonding to the electron accepting group controls the absorption spectrum of a push–pull stilbene adsorbed on amorphous silica

The photophysical and photochemical properties of push–pull photoswitches, such as stilbene derivatives, are very sensitive to their surroundings, allowing, e.g., for the control of the spectral properties or alternatively for probing the molecular environment. Here, we investigate how various adsorption motifs of 4-(N, N-Dimethylamino)-4’-nitrostilbene (DANS) on an amorphous glass surface influence its absorption spectra. Particular attention is given to the prominent first bright charge transfer state and the factors governing these modifications. The absorption spectra is simulated using time-dependent density functional theory on a large set of adsorption geometries that exhibit different kinds of molecule–surface interactions. We find that C–H⋯O interactions of the methyl or phenyl moieties with the glass affect the spectrum only marginally, whereas the dispersion interaction of the π system with the surface tends to diminish the intensity of the first absorption band. Moreover, an enhancement of the push–pull properties of DANS and a significant redshift occur whenever O–H⋯O hydrogen bonds with the NO2 group are present, whereas a hydrogen bond O–H⋯N to the NMe2 group results in a blueshift.

Nonemissive Iridium(III) Solvent Complex as a Self-Reporting Photosensitizer for Monitoring Phototherapeutic Efficacy in a "Signal on" Mode.

Photodynamic therapy (PDT) has long been receiving increasing attention for the minimally invasive treatment of cancer. The performance of PDT depends on the photophysical and biological properties of photosensitizers (PSs). The always-on fluorescence signal of conventional PSs makes it difficult to real-time monitor phototherapeutic efficacy in the PDT process. Therefore, functional PSs with good photodynamic therapy effect and self-reporting properties are highly desired. Here, two nonemissive iridium(III) solvent complexes, [(dfppy)2Ir(DMSO)]Cl (Ir-DMSO, dfppy = 2,4-difluorophenyl)pyridine, DMSO = dimethyl sulfoxide) and [(dfppy)2Ir(ACN)]Cl (Ir-ACN, ACN = acetonitrile) as PSs, were synthesized. Both of them exhibit intense high-energy absorption bands, low photoluminescence (PL) emission, and low dark toxicity. Thanks to the lower dark toxicity of Ir-DMSO, we chose it as a PS for further PDT. In this work, Ir-DMSO functions as a specific PL "signal on" PS for self-reporting therapeutic efficacy during its own PDT process. Colocalization experiments indicated that Ir-DMSO accumulated in the endoplasmic reticulum and mitochondria. Under light irradiation, Ir-DMSO not only exhibited the ability to kill cancer cells but also presented a "signal on" PL response toward cell death. During Ir-DMSO-induced PDT, cell death modality was further investigated and immunogenic cell death was revealed, in which main hallmarks, including ROS generation, upregulation of surface-exposed calreticulin, high-mobility group box 1, and adenosine triphosphate secretion, were observed. Thanks to the specific coordination reaction between Ir-DMSO and histidine (His)/His-containing proteins, the phototherapeutic efficacy can be monitored in real time without other signal probes. This work provides a new and promising strategy for the development of PSs with self-reporting ability, which is of great importance for imaging-guided PDT.

Morphological and Structural Characterization of Encapsulated Arginine Systems for Dietary Inclusion in Ruminants

This research evaluated two methods of arginine encapsulation, melt emulsification and nanoprecipitation, using a lipid matrix of carnauba wax and commercial polymers (Eudragit®) as a protective material. The ratios of wax–arginine were 1:1, 2:1, 3:1, and 4:1, while those of Eudragit® RS:RL were 30:70 and 40:60 in proportions of 1:0.5 and 1:1 Eudragit®–arginine. The microcapsules were morphostructurally characterized by scanning electron microscopy, and a microelement analysis was performed via energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. Additionally, in vitro digestibility was used to determine the protection efficiency. Both encapsulated systems presented regular (crystals) and spherical (microcapsules) polyhedral morphologies. Qualitative nitrogen decreased significantly as the wax ratio increased in the wax–arginine formulations. The formulations with a 1:1 Eudragit:–arginine ratio (1000 mg arginine) produced a higher nitrogen content in the encapsulated systems than the formulations containing 500 mg of arginine. The 2:1 and 3:1 wax–arginine formulations had the lowest degradability after 5 h of rumen fluid exposure (40.7 and 21.26%, respectively) in comparison with 100% unencapsulated arginine. The 3:1 wax–arginine formulation is an efficient encapsulating system which protects against rumen degradation. The more intense absorption bands at 1738 cm−1 and 1468 cm−1 associated with the C=O and C-H groups in carnauba wax indicate that arginine was more protected than in the other systems.

Spectator Exciton Effects in Nanocrystals III: Unveiling the Stimulated Emission Cross Section in Quantum Confined CsPbBr3 Nanocrystals.

Quantifying stimulated emission in semiconductor nanocrystals (NCs) remains challenging due to masking of its effects on pump-probe spectra by excited state absorption and ground state bleaching signals. The absence of this defining photophysical parameter in turn impedes assignment of band edge electronic structure in many of these important fluorophores. Here we employ a generally applicable 3-pulse ultrafast spectroscopic method coined the "Spectator Exciton" (SX) approach to measure stimulated-emission efficiency in quantum confined inorganic perovskite CsPbBr3 NCs, the band edge electronic structure of which is the subject of lively ongoing debate. Our results show that in 5-6 nm CsPbBr3 NCs, a single exciton bleaches more than half of the intense band edge absorption band, while the cross section for stimulated emission from the same state is nearly 6 times weaker. Discussion of these findings in light of several recent electronic structure models for this material proves them unable to simultaneously explain both measures, proving the importance of this new input to resolving this debate. Along with femtosecond time-resolved photoluminescence measurements on the same sample, SX results also verify that biexciton interaction energy is intensely attractive with a magnitude of ∼80 meV. In light of this observation, our previous suggestion that biexciton interaction is repulsive is reassigned to hot phonon induced slowdown of carrier relaxation leading to direct Auger recombination from an excited state. The mechanism behind the extreme slowing of carrier cooling after several stages of exciton recombination remains to be determined.

Нитрозирование лигносульфонатов в условиях твердофазного катализа

Lignosulfonates are the most common commercial lignin-based product due to their unique properties. Various methods are known for modifying lignosulfonates and lignosulfonic acids. This article presents the results of the development of a new approach to the production of nitrosated lignosulfonic acids. The method is based on a reaction catalyzed by cation exchange resins in the H-form: KU-2-8 cation exchanger and wofatite. The influence of reagent consumption and reaction duration on the course of nitrosation has been studied. The dynamics of the proposed nitrosation practically coincides with the dynamics of a similar reaction using sulfuric acid by the known method. The optimal consumption of sodium nitrite equals 15 %, and the optimal consumption of cation exchanger equals 100 % by weight of lignosulfonates. During the nitrosation of lignosulfonates, significant changes in the electronic spectra occur in the region of 280...500 nm. Two overlapping absorption bands appear with maxima at 300 and 330 nm, as well as an intense absorption band at 430 nm, due to nitroso groups conjugated with the aromatic nuclei of phenylpropane units. To analyze the ionization spectra, they have been deconvoluted. The resulting spectra are well approximated by 5 Gaussians with an error of no more than 5 %. Two options for carrying out the nitrosation reaction of lignosulfonates have been proposed: under static and dynamic conditions. It has been established that under dynamic conditions, nitroso derivatives of lignosulfonic acids are formed that do not contain metal cations, and the pH of the resulting solutions does not exceed 1.4. The elemental compositions of the isolated initial and nitrosated lignosulfonic acids have been determined. The nitrogen content of lignosulfonic acids has increased from 0.32 (initial) to 2.17 % (nitrosated). In addition, under dynamic conditions, an additional stage of separating the cation exchanger from the reaction medium by filtration is not required. New bands have appeared in the IR spectrum of nitrosated lignosulfonic acids: at 1540 cm–1, which is due to the presence of nitroso groups, and a wide absorption band at 1700...1715 cm–1, which can be caused by vibrations of the carboxyl group or the quinone monooxime tautomeric form of the guaiacyl structures of lignosulfonic acids.

Dibenzothiophene Bridged Bis‐Bodipy and Bis‐Metal Dipyrrin Complexes

AbstractDibenzothiophene (DBT) bridged bis‐dipyrromethane was synthesized by treating readily available 4,6‐di(p‐formylphenyl) dibenzothophene with pyrrole under acid catalyzed conditions. The DBT bridged bis‐dipyrromethane was further oxidized with DDQ to afford the DBT bridged bis‐dipyrrin which was used as a ligand to prepare DBT bridged bis‐BODIPY, bis‐Ni(II) dipyrrin and bis‐Pd(II) dipyrrin complexes by treating the ligand with BF3 ⋅ Et2O, Ni(acac)2 and Pd(acac)2 respectively under mild reaction conditions. The DBT‐bridged bis‐BODIPY and bis‐metal dipyrrin complexes were thoroughly characterized and studied by HR‐MS, 1D & 2D NMR, absorption, fluorescence, cyclic voltammetry and DFT techniques. The bis‐BODIPY and bis‐Pd(II) dipyrrin showed highly intense absorption band at ~500 nm along with one low intense absorption band at 340 nm whereas the bis‐Ni(II) dipyrrin complex showed slightly broadened blue shifted high intense band at 490 nm along with one additional band at 426 nm. The bis‐BODIPY was fluorescent with fluorescence band at 524 nm and quantum yield of 0.031 whereas bis‐M(II) dipyrrin complexes were nonfluorescent. DFT optimized structures revealed that the BODIPY units are more planar with the dibenzophene moiety in bis‐BODIPY with an angle of ∼5.68°. However, in 3‐Pd and 3‐Ni, the M(II)‐dipyrrin units are much more deviated from the dibenzothiophene plane with an angle of 12.81°–14.23°.

Integrated Intensities of the Main Absorption Band of С2HD in the 6530–6627 cm–1 Region

Integrated Intensities of the Main Absorption Band of С2HD in the 6530–6627 cm–1 Region