Cobalt Unit Research Articles

Practical and efficient oxygenation of benzylic C-H bonds with dioxygen catalyzed by two-dimensional porous organic frameworks possessing porphyrin cobalt(II) units

Metalloporphyrin T(4-Br)PPCo was used in the construction of two-dimensional porous organic framework materials (2D POFs) in order to achieve the direct benzyl C-H bonds oxygenation. In order to prevent the disordered diffusion of free radicals in 2D POFs, a restricted reaction channel was constructed, and heterogeneous catalysis was applied to decrease the deep oxygenation of partial oxygenation products due to central metal sites. All 2D POFs were characterized as amorphous microporous materials containing highly and uniformly dispersed Co2+. It was used to partially oxygenate C-H bonds at benzyl position employing dioxygen in solvent-free condition, and the conversion and selectivity were improved at the same time, especially when residual -B(OH)2 and -Br were capped. Compared with T(4-Br)PPCo, the substrate conversion increased from 39 % to 66 %, and the selectivity for 4-nitroacetophenone increased from 66 % to 91 %. The reaction mechanism, apparent kinetics and substrate compatibility were also studied. In this work, it provided a guiding reference for the effective C-H bonds oxygenation and other free radical based chemical reactions. The use of POFs in catalytic chemistry was further broadened, and a successful method for improving the catalytic characteristics of POFs by capping the remaining active groups was suggested.

Tricoordinated Single-Atom Cobalt in Zeolite Boosting Propane Dehydrogenation.

Propane dehydrogenation (PDH) reaction has emerged as one of the most promising propylene production routes due to its high selectivity for propylene and good economic benefits. However, the commercial PDH processes usually rely on expensive platinum-based and poisonous chromium oxide based catalysts. The exploration of cost-effective and ecofriendly PDH catalysts with excellent catalytic activity, propylene selectivity, and stability is of great significance yet remains challenging. Here, we discovered a new active center, i.e., an unsaturated tricoordinated cobalt unit (≡Si-O)CoO(O-Mo) in a molybdenum-doped silicalite-1 zeolite, which afforded an unprecedentedly high propylene formation rate of 22.6 molC3H6 gCo-1 h-1 and apparent rate coefficient of 130 molC3H6 gCo-1 h-1 bar-1 with >99% of propylene selectivity at 550 °C. Such activity is nearly one magnitude higher than that of previously reported Co-based catalysts in which cobalt atoms are commonly tetracoordinated, and even superior to that of most of Pt-based catalysts under similar operating conditions. Density functional theory calculations combined with the state-of-the-art characterizations unravel the role of the unsaturated tricoordinated Co unit in facilitating the C-H bond-breaking of propane and propylene desorption. The present work opens new opportunities for future large-scale industrial PDH production based on inexpensive non-noble metal catalysts.

Investigation on trommeled legacy waste from full-scale mining of old dumpsites: Suitable for valorization or scientific disposal?

The burgeoning interest in resource recovery from old dumpsites has significantly propelled the adoption of Landfill Mining (LFM) in recent years. This study is centred around evaluating the quality of materials recovered from the full-scale LFM activities at two major dumpsites in India, focusing on the valorization potential of the segregated legacy waste. A detailed analysis was conducted on the segregated waste fractions based on particle size (−30 mm, 30 to 6 mm, and −6 mm, as sourced from the sites), employing both batch and column leaching methods across a range of liquid-to-solid (L/S) ratios (0.1–10.0 L/kg).The findings reveal a pronounced concentration of contaminants within the −6 mm fraction compared to the 30 to 6 mm and −30 mm fractions. Column leaching tests revealed a reduction in contaminant concentration, correlating with incremental changes in L/S ratio. Notably, this trend remained consistent across varying particle sizes and specific type of contaminants assessed. Notably, color intensity of leachate reduced significantly from 720 to 1640 Platinum Cobalt Units (PCU) at an L/S ratio of 0.1 L/kg to a minimal 94–225 PCU at an L/S of 10 L/kg. Dissolved salts emerged as a primary concern, marking them as significant contaminants in both leaching methods. The analysis confirmed that the segregated fractions comply with the USEPA Waste Acceptance Criteria (WAC), permitting their disposal in non-hazardous waste landfills. However, the elevated presence of dissolved salts, exceeding reuse limits by 5–35 times, limits their open or unrestricted reuse. Despite this, isolated reuse aligns with regulations from the Netherlands and Germany, suggesting viable pathways for compliant utilization. Geotechnical assessments indicate the potential for repurposing the −30 mm fraction as alternative earthfill and construction material. While heavy metal leaching does not pose significant concerns, the prevalent unscientific disposal practices near urban settlements highlight potential human health risks.This investigation enriches the understanding of the physicochemical properties, leaching behaviour, and reuse potential of segregated legacy waste, offering crucial insights for civic authorities in determining appropriate reuse and disposal strategies for such materials.

New cobalt-based metal-organic frameworks for catalysing sulfite in the degradation of reactive brilliant red.

Advanced oxidation processes utilizing metal-organic frameworks (MOFs) to enhance the catalytic degradation efficiency of synthetic dyes in wastewater require a thorough understanding of the activation mechanism. Herein, four new MOFs, named [Co(Hchtc)(bpe)] (1), [Co(Hchtc)(bpy)]·H2O (2), [Co1.5(Hcptc)(bpy)0.5(H2O)2]·2H2O (3) and [Co2(cptc)(bpe)2(H2O)]·H2O (4) (H3chtc = cyclohexane-tricarboxylic acid, H4cptc = cyclopentane-tetracarboxylic acid, bpe = trans-1,2-(bis(4-pyridyl)ethene), bpy = 4,4'-bipyridine), were exploited as catalysts in the degradation of X3B by the activation of sulfites. Complexes 1 and 2, the first MOFs constructed with H3chtc, are similar two-dimensional layered structures composed of double organic linkers and dinuclear units in which the coordination numbers of cobalt ions are five and six, respectively; complex 3 is also a layered framework assembled with six-coordinated trinuclear cobalt units and bpy, whereas complex 4 is a three-dimensional framework including both 5- and 6-coordinated cobalt ions. Interestingly, catalysts 1/SO32- and 4/SO32- demonstrate a superior degradation efficiency on X3B, while 2/SO32- and 3/SO32- exhibit moderate degradation efficacy on X3B. Further investigations suggest that both the adsorption capacity of the dye and the coordination vacancy on the metal ions contribute to the degradation process, with the latter exerting an activation effect of sulfite ions.

Metamagnetism in a coordination polymer built of trimeric cobalt units and melamine.

A coordination polymer of linear trimeric cobalt units and melamine has been synthesized. The magnetic isotherms of violet coloured crystals as long as 400 μm show a field-induced transition in an external field of about 2 T at temperatures approximately below 2 K. It is addressed that by assuming the coexistent positive and negative exchange between the nearest-neighbour spins in the linear trimer, this metamagnetism can be interpreted as a transition from antiferromagnetic to ferromagnetic exchange within each trimeric spin cluster. Although weak inter-cluster or inter-chain exchange to yield a long-range magnetic order is another possible and often attributed origin of metamagnetism in low-dimensional spin systems, this study demonstrates the significance of the exchange flip within each cluster in clustered spin networks.

The regulation research of topology and magnetic exchange models of CPs through Co(II) concentration adjustment

We have designed and synthesized two new Co-CPs by modulating the concentration of cobalt ions, namely [Co3(HL)2(4,4′-bibp)3(H2O)4]n (1) and {[Co9(L)4(4,4′-bibp)4(H2O)6(μ2-OH)2]·4,4′-bibp·2H2O}n (2) (H4L ​= ​1,1′,2′,1″-terphenyl-4,4′,4″,5′-tetracarboxylic acid and 4,4′-bipb ​= ​1,4-di(pyridin-4-yl)benzene). CP 1 is a three-dimensional (3D) pillar-layered network constructed by HL3− and bridging 4,4′-bibp co-ligands with a 10-connected (424.512.68.7) topology. CP 2 is a 3D reticular framework with (4,4,5,5,6)-connected topology. The structural diversity of the two CPs suggests that the cluster numbers and the different local coordination geometries of Co(II) ions can be induced by the reaction material ratio. Focusing on the bridging system, CP 1 cnsists of centrosymmetric trinuclear octahedral cobalt(II) units, and within the units, the cobalt(II) ions are found to be ferromagnetically coupled. CP 2 cnsists of centrosymmetric nonanuclear cobalt(II) units, including five octahedral and four trigonal-bipyramidal cobalt(II) ions. Antiferromagnetic interactions are observed in the partial triangular units, and also in the other parts, showing an overall antiferromagnetic behavior.

Impact of Counteranion on Reversible Spin-State Switching in a Series of Cobalt(II) Complexes Containing a Redox-Active Ethylenedioxythiophene-Based Terpyridine Ligand.

The self-assembly of a redox-active ethylenedioxythiophene (EDOT)-terpyridine-based tridentate ligand and cobalt(II) unit with different counteranions has led to a series of new cobalt(II) complexes [Co(L)2](X)2 (X = BF4 (1), ClO4 (2), and BPh4 (3)) (L = 4'-(3,4-ethylenedioxythiophene)-2,2':6',2″-terpyridine). The impact of various counteranions on stabilization and spin-state switching of the cobalt(II) center was explored through detailed magneto-structural investigation using variable temperature single-crystal X-ray diffraction, magnetic, spectroscopic, electrochemical, and spectroelectrochemical studies. All three complexes 1-3 consisted of an isostructural dicationic distorted octahedral CoN6 coordination environment offered by the two L ligands in a bis-meridional fashion and BF4-, ClO4-, and BPh4- as a counteranion, respectively. Complex 2 with ClO4- counteranion showed a reversible, gradual, and nearly complete spin-state switching between low-spin (LS) (S = 1/2) and high-spin (HS) (S = 3/2) states, while an incomplete spin-state switching behavior was observed for complexes 1 (BF4-) and 3 (BPh4-) in the measured temperature range of 350-2 K. The non-covalent cation-anion interactions played a significant role in stabilizing the spin-state in 1-3. Additionally, complexes 1-3 also exhibited interesting redox-stimuli-based reversible paramagnetic HS cobalt(II) (S = 3/2) to diamagnetic LS cobalt(III) (S = 0) conversion, offering an alternate way to switch the magnetic properties.

Immune System Response after Immobilization Stress in the Background of Ionizing Radiation

We studied the combined effect of gamma radiation (6 Gy, remote period) and immobilization stress on immunological reactivity. Materials and methods. To address this, we carried out experiments on 40 white male Wistar rats weighing 220 ± 20 g, which were divided into 4 groups: Group I - intact animals, group II - animals exposed to gamma radiation (dose of 6 Gy), group III - animals exposed to immobilization stress and group IV - animals exposed to combined exposure to gamma radiation (dose of 6 Gy) and immobilization stress. Animals in groups II and IV were irradiated 90 days before the study on the TERAGAM radiotherapeutic cobalt unit. In groups III and IV, animals were modeled for acute immobilization stress by immobilization for 6 h in bright light. Results. At the early period of immobilization stress, all indicators of the immune system, such as cellular, humoral and nonspecific phagocytic links of immunity were activated, indicating the activation of the general adaptive syndrome of the organism. The suppressive action of gamma radiation on the immune system was preserved in a remote period, with this suppression being revealed not only on the T-cellular link, but also on nonspecific phagocytic links, and the functional metabolic activity of neutrophils. In the remote period after the combined effect of sublethal gamma radiation and immobilization stress in the early stage of the adaptation syndrome, there was a decrease in all cells of the T system of immunity, in the functional ability of leukocytes, and in the mononuclear phagocytic system of the body. The experimental immobilization-radiation pathological process was accompanied by disorders of the functional activity of the essential adaptive systems of the body. Based on our results, we could conclude about the dominant role of ionizing radiation in immunological reactivity.
 HIGHLIGHTS
 
 At an early stage, after exposure to stress, the general adaptation syndrome is activated in the body
 The suppressive effect of gamma radiation on the immune status and phagocytic activity persists in the long term
 The pathological process that occurs under the combined effects of radiation and immobilization stress is accompanied by a violation of the functional activity of the most important adaptive systems of the body
 Under the combined influence of radiation and non-radiation factors, the radiation factor has a predominant influence
 
 GRAPHICAL ABSTRACT

Tuning three coordination polymers with dinuclear metal units via pH control: syntheses, structures, and magnetic properties

The self-assembly of three coordination polymers with dinuclear metal units, namely {[Co2(bpta)(phen)2]·2H2O}n (1), {[Co2(bpta)(phen)(H2O)]·4H2O·CH3CN}n (2), and {[Ni2(bpta)(phen)(H2O)]·2H2O·0.5CH3CN}n (3), has been tuned via the control of pH under solvothermal conditions. The structures are characterized by FTIR spectroscopy, elemental analysis, single-crystal X-ray diffraction and powder X-ray diffraction analysis. The H4bpta ligands exhibit μ6-κ2:κ1:κ2:κ1 and μ7-κ2:κ2:κ1:κ2 coordination modes in the complexes 1–3. The octahedral metal ions are connected by carboxylate and μ2-O bridges to form [Co2(μ-OCO)2] and [M2(μ-OCO)2(μ2-O)] SBUs, respectively. Complex 1 shows a 2D framework with {44.62} sql-net topology. Complexes 2 and 3 display 3D networks with {42.84} pts-net topology. Magnetic studies reveal that 1 and 2 exhibit weak antiferromagnetic interactions in the double- and triple-bridged dimeric cobalt(II) units (J ​= ​−0.53(6) cm−1 for 1, and −E2/k ​= ​−0.77 ​K for 2, respectively). Complex 3 shows a ferromagnetic interaction (J ​= ​2.44(1) cm−1) between two dimeric Ni(II) ions.

Factors Affecting the Intensity of Color Released In Water Extract by Soil-Like Material Obtained From Mining of Old MSW Dumps

This paper presents the analysis of release of dark-colored leachate from soil-like material (SLM) mined from three old municipal solid waste dump sites of before its reuse as earth-fill. If SLM is to be re-used in earth-fill, the release of dark-colored leachate can cause coloration of the surrounding water bodies. Laboratory studies (in terms of single batch leaching) were undertaken to quantify the release of color and identify the source/cause of the phenomenon. Influence of repeated washing, heating at various temperature, and aeration of SLM on the intensity of release of color was identified. Correlation of color with total dissolved solids and volatile dissolved solids was also established. The intensity of color of water extract from SLM in platinum cobalt unit (PCU) was found to in the range of 288-712, 465-485 and 740-925 from Delhi, Kadapa and Hyderabad dumpsites respectively. In contrast, the intensity of color in water released from local soils was found to be 25-30 PCU. Organic content present in SLM was identified as the primary cause for the release of color. Results showed that large quantity of water (70-120 ml per gram of SLM) was required to cause significant reduction in the intensity of color. Heating of SLM to 500°C was observed to reduce the color very effectively but short-term aeration of SLM did not reduce color. Good correlation of volatile dissolved solids with color was observed which further confirmed the organic content as the main reason for the release of dark-colored leachate from SLM.

Sorption and Magnetic Properties of Oxalato-Based Trimetallic Open Framework Stabilized by Charge-Assisted Hydrogen Bonds.

We report a new structure of {[Co(bpy)2(ox)][{Cu2(bpy)2(ox)}Fe(ox)3]}n·8.5nH2O NCU-1 presenting a rare ladder topology among oxalate-based coordination polymers with anionic chains composed of alternately arranged [Cu2(bpy)2(ox)]2+ and [Fe(ox)3]3− moieties. Along the a axis, they are separated by Co(III) units to give porous material with voids of 963.7 Å3 (16.9% of cell volume). The stability of this structure is assured by a network of stacking interactions and charge-assisted C-H…O hydrogen bonds formed between adjacent chains, adjacent cobalt(III) units, and alternately arranged cobalt(III) and chain motifs. The soaking experiment with acetonitrile and bromobenzene showed that water molecules (8.5 water molecules dispersed over 15 positions) are bonded tightly, despite partial occupancy. Water adsorption experiments are described by a D’arcy and Watt model being the sum of Langmuir and Dubinin–Serpinski isotherms. The amount of primary adsorption sites calculated from this model is equal 8.2 mol H2O/mol, being very close to the value obtained from the XRD experiments and indicates that water was adsorbed mainly on the primary sites. The antiferromagnetic properties could be only approximately described with the simple CuII-ox-CuII dimer using H = −J·S1·S2, thus, considering non-trivial topology of the whole Cu-Fe chain, we developed our own general approach, based on the semiclassical model (SC) and molecular field (MF) model, to describe precisely the magnetic superexchange interactions in NCU-1. We established that Cu(II)-Cu(II) coupling dominates over multiple Cu(II)-Fe(III) interactions, with JCuCu = −275(29) and JCuFe = −3.8(1.6) cm−1 and discussed the obtained values against the literature data.

Semi‐conductive Chiral MOFs with Helixes Based on Lactic Acid Derivatives for Photo‐catalytic Reaction

AbstractA pair of new chiral Co(II) metal‐organic frameworks based on semi‐rigid lactic acid derivatives, namely, {[Co((R)‐CBA)(1,3‐DPP)(H2O)0.5] ⋅ H2O}n(1‐R) and {[Co((R)‐CBA)(1,3‐DPP)(H2O)0.5] ⋅ H2O}n (1‐S) (H2CBA=4‐(1‐carboxyethoxy) benzoic acid, 1,3‐DPP=1,3‐di(pyridin‐4‐yl)propane) were synthesized under hydrothermal conditions. The structures of complexes 1‐R and 1‐S were determined by single crystal X‐ray crystallography, revealing dinuclear cobalt units are connected through (R)‐ or (S)‐CBA2− anions that lead to the formation of enantiomeric helical chains. Helical chains are further linked together to build 3D Co‐(R)‐CBA (Co‐(S)‐CBA) framework in 1‐R(1‐S). Furthermore, more large helical chains are formed by Co(II) centers and 1,3‐DPP ligands in 1‐R and 1‐S. As a result, 1,3‐DPP ligands are introduced into complexes to stabilize the CBA−Co frameworks to obtain a four‐connected dia net. Apart from delicate structure, the UV‐vis sorption spectrum, Mott‐Schottky measurements and electrochemical impedance spectroscopy (EIS) demonstrated that complex 1‐R is a typical n‐type semiconductor with low resistance in charge transportation. Photo‐catalytic test result confirmed the complex 1‐R has catalytic activity for the degradation of RhB.

Modulator Induced Formation of a Neutral Framework Based on Trinuclear Cobalt(II) Clusters and Nitrilotribenzoic Acid: Synthesis, Magnetism, and Sorption Properties

AbstractThe solvothermal reaction of cobalt(II) chloride and 4,4′,4′′‐nitrilotribenzoic acid (H3ntb) in dmf employing a modulator based approach leads to the formation of the neutral framework with the formula [Co9(ntb)6(solv)12]n (JUMP‐3). Different mono‐ and dicarboxylic acids such as benzoic, phthalic, isophthalic, and acetic acid could be used as appropriate modulator to trigger the reaction toward the formation of the neutral framework. X‐ray crystallography revealed a three‐dimensional network composed of linear trinuclear cobalt(II) units as metal nodes and the triarylamine linkers. The topological analysis showed that the framework adopts a 3,6‐coordinated net with 3,6T80 topology. Magnetic measurements performed in the temperature range of 2–300 K indicate antiferromagnetic interactions between the cobalt(II) ions within its linear trinuclear clusters. The N2 sorption properties were investigated and show the presence of micropores, which is consistent with the presence of the 1D channels in the crystal structure of JUMP‐3.

Structure Types and Magnetic Behavior of Cobalt Nanoclusters.

Caprylic hydrazide ligands are ideal ligands for the synthesis of novel polynuclear metal complexes, because they contain many N,O coordination atoms with a strong coordination ability, abundant hydrogen-bond donors, acceptors, and large conjugation systems. Here, we successfully obtained one dodecanuclear cobalt nanocluster [CoII8CoIII4(L1)4(Py)12(CH3OH)4(CH3COO)4]·(CH3OH)13 (1) and one octadecanuclear cobalt nanocluster [CoII18(L2)6(Py)48]·(DMF)5·(CH3OH)8 (2) by using H6L1 and H6L2 ligands, respectively (Py = pyridine; DMF = dimethylformamide). The cyclic cobalt nanocluster 1 can be regarded as two pentanuclear cobalt units (Co5(N-N)4) connected by two cobalt ions, and it is a mixed-valent Co nanocluster. Every H6L1 ligand contains 10 coordination atoms, each of which coordinates with the Co ions. And every two H6L1 ligands form a structure similar to a handshake. The abnormal cylindrical cobalt nanocluster 2 can be regarded six trinuclear cobalt units Co3(N-N)2 connected by one L26- ligand, and every L26- ligand splits the structure on both sides, with a twisted cyclohexane in the middle. AC magnetic susceptibilities show that nanocluster 1 exhibits no frequency-dependent behavior, but nanocluster 2 shows an obviously single-molecule magnetic behavior, and the relaxation process of the energy barrier is 20.4 K.

Highly Robust Tetranuclear Cobalt-Based 3D Framework for Efficient C2H2/CO2 and C2H2/C2H4Separations

A novel noninterpenetrated tetranuclear cobalt(II)-based metal-organic framework, (NH4)2·[Co4(μ3-OH)2(ina)2(pip)3]·4EtOH·H2O (simplified as NbU-10·S), constructed by mix linkers was synthesized by a hydrothermal method. Interestingly, the presence of a hydrophobic benzene ring in the organic linker makes NbU-10·S exhibit high stability in high temperature and even in aqueous solution over a wide pH range of about 4-13. Magnetic studies showed that the tetranuclear cobalt(II) units in NbU-10·S show dominant antiferromangetic properties. However, in the absence of Lewis basic functional sites and open metal sites in the material, NbU-10 still displays high C2H2/CO2 and C2H2/C2H4 selectivity in ideal adsorbed solution theory calculations and dynamic breakthrough experiments. Moreover, density functional theory calculations were performed to identify the adsorption characteristics of different gas molecules.

Анализ результатов ТЛД/РФЛД аудитов МАГАТЭ дистанционного радиотерапевтического оборудования в России за последние 20 лет

The article addresses results of IAEA thermoluminescent (TL) and radio-photoluminescent (RPL) postal dose audit of the external beam radiotherapy (EBRT) equipment, linacs and cobalt units, performed in Russia over the past 20 years between 1999 and 2019. The aim of the work was to evaluate results of IAEA dose audit: to compare the dose determined at the IAEA Dosimetry La-boratory with the dose stated by the Russian participant. The acceptable deviation between the doses is ≤5%. In the first-time audit 817 dosimeter sets were used, 430 of them were irradiated with 60Co of EBRT machines and 387 sets were irradiated with bremsstrahlung radiation of vari-ous energies. To search factors that affected the clinical dosimetry quality 133 beams, mainly 60Co gamma-ray beams, were retested. Over the twenty-year period a total of 9% of bremsstrah-lung beams and 27% of gamma-ray beams exceeded the 5% tolerance interval. The observed deviation may be resulted from the use of outdated radiotherapy equipment, lack of trained workers with high-level experience and competence in medical radiology, medical physics, IT, as well as lack of appropriate dosimetry systems. The common reason of observed dosimetry audit outcomes may be the result of inconsistency between irradiation geometry calculated with the use of treatment planning system and the true irradiation geometry, as well as errors of calcula-tion. Having assessed the worksheets we have found many partially completed sheets, infor-mation on irradiation conditions and dose calculation process was unavailable or incorrect, all mentioned made it difficult to analyze causes of observed deviations. Nonetheless, we witness a positive trend in the dose audit outcomes, at the same time, the amount of errors in Russian worksheets is still larger than in other countries-participants of the IAEA/WHO audit. It is possible to improve the radiation therapy quality and to increase radiotherapy benefits and effectiveness due to expanding the practice of autonomous auditors at the Federal and regional levels, as well as organizing of specialists’ on-site visits to Radiotherapy Centers. Taking such actions makes it possible avoidance of communication problems and increase in the detection rate of true causes of observed shortcomings in clinical dosimetry quality.

Solvent-induced structural transformations of two-dimensional coordination polymers based on trinuclear cobalt unit

Three new Co(II) coordination polymers based on a flexible ligand 5-(3-carboxybenzyloxy)-isophthalic acid (H3L) namely [Co3(L)2(H2O)4]n·2nDMF (1) (DMF = N,N-dimethylformamide), [Co3(L)2(DMA)2(H2O)2]n·2nDMA (2) (DMA = N,N-dimethylacetamide) and [Co3(L)2(py)2(NMP)(H2O)]n·nNMP·nH2O (3) (NMP = N-methyl-2-pyrrolidone) have been assembled using different solvent. The different size of solvent molecular can affect the structure of the compounds. Interestingly, three compounds all constructed by the same trinuclear unit of [Co3O12] to exhibit two-dimension architecture with kgd topology. In this building block, there are coordinated water and molecules having the carbonyl group as terminal ligands coordinated with cobalt ions, providing a good example for studying the coordinated solvent exchange. When coordinated solvent molecules were replaced by pyridine molecules, which made two Co ions in asymmetric coordination. This symmetry breaking might the reason for compound 3 crystallizes in the noncentrosymmetric space group. Also, magnetic investigation on compound 1 indicates antiferromagnetic coupling exchange interactions between Co(II) ions in the trinuclear cluster unit.

Stereotactic radiosurgery and radiotherapy for acoustic neuromas

Neuromas are benign intracranial tumors with indolent natural history. Surgery is the mainstay of treatment and only after the introduction of single-fraction stereotactic radiosurgery (SRS), radiotherapy emerged as an alternative viable option. In this review, we focused on SRS or conventionally fractionated stereotactic radiotherapeutic (FSRT) approaches. We described the results of different doses used for SRS and FSRT, the current status, and a comparison between the two radiotherapy approaches. Stereotactic radiotherapy techniques aim to control tumor growth with minimal toxicity. SRS using either a cobalt unit or a linear accelerator has given high rates of tumor control and of cranial nerve function preservation with marginal doses range of 12-14Gy. Fractionated stereotactic radiotherapy (FSRT) is optimal for tumors larger than 3cm. Doses as low as 50.4Gy provide excellent control rates and low morbidity. Overall, both SRS and FSRT are equally effective and safe options for neuroma patients who do not need immediate surgical decompression.

Two metal–organic frameworks based on 2,5-thiophenedicarboxylic acid and semi-rigid bis-imidazole ligand: Luminescence, magnetism and electrocatalytic activities

Tuning metal ion from Cd(II) to Co(II) in the presence of 2,5-thiophenedicarboxylic acid (H2tdc) and semi-rigid bis-imidazole ligand 4-bis(1H-imidazol-1-yl-methyl)benzene(bimb), two metal–organic frameworks, [Cd3(bimb)(μ4-tdc)3(DMA)2]·2DMA (1) and [Co2(bimb)(μ2-H2O)(μ3-tdc)2(DMF)2]·H2O (2), have been generated under solvothermal condition. All two frameworks with (412, 63) topology are pillared by bimb ligands, and the difference is that there exist trinuclear cadmium clusters gathered by tdc ligands in the structure of 1, but binuclear cobalt units in 2. Interestingly, with the change of metal ion from Cd(II) to Co(II), compound 1 displays good luminescent property at room temperature, and compound 2 exhibits not only antiferromagnetic interaction, but also electrocatalytic activity toward the oxidation of ascorbic acid.

An Audit for Radiotherapy Planning and Treatment Errors From a Low–Middle-Income Country Centre

AimsTo report the findings of an audit for radiotherapy errors from a low–middle-income country (LMICs) centre. This would serve as baseline data for radiotherapy error rates, their severity and causes, in such centres where modern error reporting and learning processes still do not exist. Materials and methodsA planned cross-sectional weekly audit of electronic radiotherapy charts at the radiotherapy planning and delivery step for all patients treated with curative intent was conducted. Detailed analysis was carried out to determine the step of origin of error, time and contributing factors. They were graded as per indigenous institutional (TMC) radiotherapy error grading (TREG) system and the contributing factors identified were prioritised using the product of frequency, severity and ease of detection. ResultsIn total, 1005 consecutive radically treated patients' charts were audited, 67 radiotherapy errors affecting 60 patients, including 42 incidents and 25 near-misses were identified. Transcriptional errors (29%) were the most common type. Most errors occurred at the time of treatment planning (59.7%), with “plan information transfer to the radiation oncology information system” being the most frequently affected sub-step of the radiotherapy process (47.8%). More errors were noted at cobalt units (52/67; 77.6%) than at linear accelerators. Trend analysis showed an increased number of radiotherapy incidents on Fridays and near-misses on Mondays. Trend for increased radiotherapy errors noted in the evening over other shifts. On severity grading, most of the errors (54/60; 90%) were clinically insignificant (grade I/II). Inadequacies and non-adherence towards standard operating procedures, poor documentation and lack of continuing education were the three most prominent causes. ConclusionPreliminary data suggest a vulnerability of LMIC set-up to radiotherapy errors and emphasises the need for the development of longitudinal prospective processes, such as voluntary reporting and a continued education system, to ensure robust and comprehensive safe practises on par with centres in developed countries.