Unusual Complex Research Articles

Combined first-principles and Boltzmann transport theory methodology for studying magnetotransport in magnetic materials

Unusual magnetotransport behaviors, such as temperature-dependent negative magnetoresistance (MR) and bowtie-shaped MR, have puzzled us for a long time. Although several mechanisms have been proposed to explain these phenomena, the absence of comprehensive quantitative calculations has made these explanations less convincing. In our work, we introduce a methodology to study magnetotransport behaviors in magnetic materials. This approach integrates the anomalous Hall conductivity induced by the Berry curvature, with a multiband ordinary conductivity tensor, employing a combination of first-principles calculations and semiclassical Boltzmann transport theory. Our method also incorporates the temperature dependence of the relaxation time and the anomalous Hall conductivity, as well as the field dependence of the anomalous Hall conductivity. We initially test this approach on models, obtaining distinct behaviors of magnetoresistance and Hall resistivity across several types of magnetic materials, and then apply it to a Weyl semimetal Co3Sn2S2. The results, which align well with experimental observations in terms of magnetic field and temperature dependencies, demonstrate the efficacy of our approach. This methodology provides a comprehensive and efficient means to understand the underlying mechanisms of the unusual complex behaviors observed in magnetotransport measurements in magnetic materials. Published by the American Physical Society 2024

DNA interaction and cytotoxicity of a new asymmetric dimer cobalt(II) complex [Co(phen)2(Cl2)]3(H2O).[Co(phen)2(Cl)(H2O)](Cl)

The new, unusual and asymmetric cobalt(II) complex, [Co(phen)2(Cl2)]3(H2O).[Co(phen)2(Cl)(H2O)](Cl) (phen ​= ​1,10-phenanthroline), has been synthesized and characterized structurally by regular spectral and single crystal XRD analysis. An asymmetric complex crystallized in a monoclinic system with space group P21/c, a ​= ​14.093(5) Å, b ​= ​24.089(5) Å, c ​= ​14.241(5) Å, α ​= ​90.000(5)°, β ​= ​98.010(5)°, and γ ​= ​90.000(5)°. DNA binding interactions of complex with calf thymus DNA (CT-DNA) has investigated by UV–Vis absorption, ethidium bromide displacement assay, viscometric and cyclic voltammetric titrations, and the results infer an intercalation mode of binding. Complex cleaves effectively plasmid pBR322 DNA, and exhibits remarkable cytotoxic activity against human colon cancer cell line (HCT15).

Fluoride Ingestion Induces Formation of Unusual Macromolecular Complexes in Gut Lumen Which Retard Absorption of Essential Minerals and Trace Elements by Chelation.

This study investigates the impact of chronic fluoride exposure on the absorption of essential minerals in the gut and explores the mechanisms underlying mineral deficiencies due to fluoride ingestion. Male Wistar rats were randomly assigned to three groups: group 1 (G-1) served as the control (non-fluoride exposed), while group 2 (G-2) and group 3 (G-3) received human equivalent doses (HED) of fluoride (50 and 100ppm ad libitum, corresponding to 5 and 10ppm in humans, respectively) for 75days. Serum fluoride concentrations were measured, and the levels of essential minerals and trace elements in blood and stool were analyzed using ICP-MS. X-ray diffraction (XRD) analysis was performed on stool samples to identify chemical compounds. The chemical compounds and macromolecular complexes containing fluoride and essential minerals were identified and quantified using Match3 software. Results indicated that the blood concentrations of essential minerals were significantly lower (p ≤ 0.05) in the fluoride-exposed groups compared to the control, while excretion of essential elements in stool was significantly higher (p ≤ 0.05) in the fluoride-administered groups. XRD analysis revealed the formation of unusual macromolecular chemical complexes in the stool of fluoride-treated groups, with the types and concentrations of these compounds increasing with higher fluoride doses. The study concludes that fluoride in the stomach chelates minerals, reducing their absorption, and induces the formation of unusual high molecular weight macromolecular chelation complexes, which alter the chemical species in the gut and further impair the absorption of essential minerals.

Magnesium 4, 5, and 6 coordinate complexes with ligands bound via sp or sp2 hybridized atoms

As a metallic element of high natural abundance, magnesium finds a wide range of uses in both stoichiometric and more recently catalytic applications. This often takes advantage of the basic or nucleophilic properties of its compounds or their ability to co-complex with other organometallic compounds. However, the homoleptic chemistry of Mg(II) is heavily skewed towards alkyl and aryl ligands bound via sp2 and sp3 hybridized atoms. Here, we report our combined NMR spectroscopic and X-ray crystallographic study into much rarer alternative THF solvates of homoleptic magnesium complexes using ligands which bind via sp (alkynyl) and sp2 (imido) atoms. Specifically, we exploit the high acidity of terminal alkynes and diphenylacetonitrile to prepare tetra-solvated distorted octahedral complexes Mg(CCC6H4R-p)2(THF)4 (R = Me, CF3) and Mg(NCCPh2)2(THF)4 starting from the commercial alkyl reagent MgBu2. Adopting a similar deprotonative strategy using benzophenoneimine Ph2CNH affords the heteroleptic trinuclear complex Mg3(NCPh2)4nBu2(THF)2 with distorted tetrahedral Mg centres. Related imidomagnesium halide complexes can be accessed either by deprotonation of the imine with a Grignard reagent, or nucleophilic addition of a Grignard reagent to a nitrile, but these unusual five-coordinate complexes are unresponsive to a 1,4-dioxane induced Schlenk equilibrium shift. Employing a higher reflux temperature switching from a THF to a toluene medium permits access to the THF solvate of a homoleptic imido complex which also possesses a trinuclear constitution in Mg3(NCPh2)6(THF)2.

Reactivity of [(Cp*CoPh)(Cp*Co)(μ-TePh)(μ-k2-Te,H-TeBH3)] Toward [M(CO)5·THF] (M = Mo and W), CS2, and [Fe2(CO)9

Syntheses and structural elucidation of homo- and heterochalcogen-bridged complexes of cobalt are described. The photolytic reaction of bimetallic hydridoborate species [(Cp*CoPh)(Cp*Co)(μ-TePh)(μ-k2-Te,H-TeBH3)] (1) in the presence of [M(CO)5·THF] (M = Mo and W) afforded unprecedented tellurolate-bridged [(Cp*Co)2(μ-TePh)3]+[TePh{M(CO)5}2]- (M = Mo (2), W (3)) as ionic complexes with the release of BH3. Complex 2 has three bridged-TePh moieties between two Cp*Co fragments in the cation part, whereas the anionic part, [TePh{M(CO)5}2]-, shows a distorted trigonal pyramidal core. In order to synthesize mixed chalcogenate-bridged complexes having both S and Te, we carried out the photolytic reaction of 1 with CS2. Although the objective of generating mixed chalcogen-bridged complex [(Cp*Co)2(μ-TePh)2(μ-S)] was not achieved, the reaction yielded an unusual bimetallic thiotellurite complex [(Cp*Co)2(μ-S3TeS3-κ2S:κ2Te:κ2S')] (4). Complex 4 has two wings, each consisting of three sulfur atoms, that are connected to two Co-atoms and one Te-atom. Further, to synthesize the Fe analogue of 2 and 3, a similar reaction was carried out with [Fe2(CO)9]. However, the reaction led to the formation of the trimetallic complex [Cp*Co(CO)(μ3-Te)2{Fe2(CO)6}] (5). These complexes were characterized by employing different multinuclear NMR, IR spectroscopies, single-crystal X-ray diffraction analyses, and mass spectrometry. Additionally, computational analyses of these chalcogen-bridged neutral and ionic complexes were conducted to offer insight into their bonding.

Dicarbonyl[10,10-dimethyl-5,15-bis(pentafluorophenyl)biladiene]ruthenium(II): discovery of the first ruthenium tetrapyrrole cis-dicarbonyl complex by X-ray and electron diffraction.

Dicarbonyl[10,10-dimethyl-5,15-bis(pentafluorophenyl)biladiene]ruthenium(II), [Ru(C33H16F10N4)(CO)2] or Ru(CO)2[DMBil1], is the first reported ruthenium(II) cis-dicarbonyl tetrapyrrole complex. The neutral complex sports two carbonyls and an oligotetrapyrrolic biladiene ligand. Notably, the biladiene adopts a coordination geometry that is well distorted from square planar and much more closely approximates a seesaw arrangement. Accordingly, Ru(CO)2[DMBil1] is not only the first ruthenium cis-dicarbonyl with a tetrapyrrole ligand, but also the first metal biladiene complex in which the tetrapyrrole does not adopt a (pseudo-)square-planar coordination geometry. Ru(CO)2[DMBil1] is weakly luminescent, displaying λem= 552 nm upon excitation at λex= 500 nm, supports two reversible 1 e- reductions at -1.45 and -1.73 V (versus Fc+/Fc), and has significant absorption features at 481 and 531 nm, suggesting suitability for photocatalytic and photosensitization applications. While the structure of Ru(CO)2[DMBil1] was initially determined by X-ray diffraction, a traditionally acceptable quality structure could not be obtained (despite multiple attempts) because of consistently poor crystal quality. An independent structure obtained from electron diffraction experiments corroborates the structure of this unusual biladiene complex.

Sporadic binding of perchlorate and dicyanamide ions in trinuclear CuII2NiII complexes with a reduced di-Schiff base ligand: Synthesis, structures and spectral properties

Two new unusual trinuclear linear heterometallic complexes, [(CuLR)2Ni(ClO4)2{CO(CH3)2}2]·0.17H2O (1) and [(CuLR)2Ni(N3C2)2(0.5CH3OH)2] (2) have been synthesized by using [CuLR] as a “metalloligand” (where H2LR=N,N′-bis(2-hydroxybenzyl)-1,3-propanediamine) in presence of anions perchlorate and dicyanamide, respectively. Both the complexes have been diagnosed by elemental analysis, spectroscopic investigations, and single crystal XRD study. In these complexes, the terminal “ligand complex” [CuLR] coordinates to the central nickel atom via double phenoxido oxygen atoms bridge, resulted in a linear trinuclear structures. In both structures, the anions (perchlorate for 1 and dicyanamide for 2) coordinate to the terminal Cu(II) centers of the trinuclear unit (Cu(II)-Ni(II)-Cu(II)) to complete the distorted octahedral geometry around Cu(II); whereas the central Ni(II) metal ion remains in square planar geometry. The binding of perchlorate or dicyanamide to the terminal Cu(II) instead of central Ni(II) ion is rather unusual compared to the complexes of analogous unreduced species.

Miller–Fisher syndrome – A diagnostic conundrum – A case report and review of literature

Miller–Fisher syndrome is a rare subvariant of Guillian–Barre syndrome, presenting with ophthalmoplegia, ataxia, and areflexia. We present a 37-year-old male with progressive bilateral external ophthalmoplegia with moderate left-eye ptosis. He developed myalgia, ataxia, and absent deep tendon reflexes. He was initially treated with thiamine infusion and pyridostigmine because of possible Wernicke’s encephalopathy or myasthenia with no improvement. Lumbar puncture revealed acellular smear with high protein. He was switched to IV immunoglobulin therapy proceeding which he showed improvement. We present this case due to its unusual nature and complex diagnostic conundrum.

6301541 Unusual complex neurological presentation in a pregnant patient with previous abdominoplasty

6301541 Unusual complex neurological presentation in a pregnant patient with previous abdominoplasty

The dinosaurs that weren't: osteohistology supports giant ichthyosaur affinity of enigmatic large bone segments from the European Rhaetian.

Very large unidentified elongate and rounded fossil bone segments of uncertain origin recovered from different Rhaetian (Late Triassic) fossil localities across Europe have been puzzling the paleontological community since the second half of the 19th century. Different hypotheses have been proposed regarding the nature of these fossils: (1) giant amphibian bones, (2) dinosaurian or other archosaurian long bone shafts, and (3) giant ichthyosaurian jaw bone segments. We call the latter proposal the 'Giant Ichthyosaur Hypothesis' and test it using bone histology. In presumable ichthyosaur specimens from SW England (Lilstock), France (Autun), and indeterminate cortical fragments from Germany (Bonenburg), we found a combination of shared histological features in the periosteal cortex: an unusual woven-parallel complex of strictly longitudinal primary osteons set in a novel woven-fibered matrix type with intrinsic coarse collagen fibers (IFM), and a distinctive pattern of Haversian substitution in which secondary osteons often form within primary ones. The splenial and surangular of the holotype of the giant ichthyosaur Shastasaurus sikanniensis from Canada were sampled for comparison. The results of the sampling indicate a common osteohistology with the European specimens. A broad histological comparison is provided to reject alternative taxonomic affinities aside from ichthyosaurs of the very large bone segment. Most importantly, we highlight the occurrence of shared peculiar osteogenic processes in Late Triassic giant ichthyosaurs, reflecting special ossification strategies enabling fast growth and achievement of giant size and/or related to biomechanical properties akin to ossified tendons.

Copper perchlorate catalyzed oxidative cyclisation of a novel bishydrazone ligand, formation of an unusual copper complex and in vitro biological implications

A novel hexadentate bishydrazone ligand, 1,10-bis(di(2-pyridyl)ketone) adipic acid dihydrazone (H2L1) is synthesized and characterized. With copper perchlorate as a catalytic oxidant, the ligand undergoes oxidative cyclisation and resulted in the formation of an unusual copper complex [Cu(L1a)2Cl]ClO4 (1), where L1a is 3-(2-pyridyl)triazolo[1,5-a]-pyridine. The Cu(II) complex was characterized physicochemically, while the molecular structure was confirmed by single crystal X- ray diffraction. In the complex cation, copper(II) is in a distorted trigonal bipyramidal coordination environment, surrounded by two triazolo nitrogen atoms and two pyridyl nitrogen atoms of L1a and a chloride atom. The relevant non covalent intermolecular interactions of the complex quantified using Hirshfeld surface analysis reveals that the O···H/ H···O (27.2%) contacts has the highest contribution. The solution phase bandgaps of the compounds were calculated using Tauc plot, whereas the solid-state band gaps were calculated by Kubelka-Munk model. DFT studies of the compounds indicate that the theoretical calculations corroborate with the experimental data. DPPH antioxidant activity assay of the synthesized compounds showed that the proligand H2L1 has a lower IC50 value (24.1 μM) than that of complex 1 (29.7 μM). The in vitro antibacterial activity was evaluated against Escherichia coli and Staphylococcus aureus, which revealed that complex 1 have excellent activity against E. coli, much as the standard ciprofloxacin. The cytotoxic efficacy investigation of the compounds against A549 (lung) adenocarcinoma cells suggested that H2L1 has more anticancer activity (IC50 value of 149.08 μM) than that of complex 1(IC50 value of 176.70 μM).

Gas-phase solvent-free complexation of phenolic acids in cyclodextrins: A mass spectrometric study

Phenolic acids are phytochemicals commonly existing in plants that are also beneficial to the human body after consumption. As additives in the food industry, phenolic acids typically need stabilization by encapsulation. We have been studying cyclodextrins as potential encapsulating agents, elucidating the structure and energetics of the complexes they form with phenolic acids. To highlight the role of the solvent in these interactions and to investigate the possible component ratios available to these complexes, we first carried out gas-phase studies monitored through mass spectrometry that allowed us to work in solvent-free conditions. In addition to detecting the products of these complexation equilibria qualitatively, we were also able to find conditions to quantitative determine the relative binding affinities associated with these processes. As well as on the unusual complex stoichiometry observed in the gas phase for a series of phenolic acids with α-CD, β-CD, and γ-CD. We propose an explanation of these uncommon stoichiometries through solvation effects involving the cyclodextrin host as the solvating species. We also report on the observed trends in the measured relative affinities of these interactions.

Blastocrithidia nonstop mitochondrial genome and its expression are remarkably insulated from nuclear codon reassignment.

The canonical stop codons of the nuclear genome of the trypanosomatid Blastocrithidia nonstop are recoded. Here, we investigated the effect of this recoding on the mitochondrial genome and gene expression. Trypanosomatids possess a single mitochondrion and protein-coding transcripts of this genome require RNA editing in order to generate open reading frames of many transcripts encoded as 'cryptogenes'. Small RNAs that can number in the hundreds direct editing and produce a mitochondrial transcriptome of unusual complexity. We find B. nonstop to have a typical trypanosomatid mitochondrial genetic code, which presumably requires the mitochondrion to disable utilization of the two nucleus-encoded suppressor tRNAs, which appear to be imported into the organelle. Alterations of the protein factors responsible for mRNA editing were also documented, but they have likely originated from sources other than B. nonstop nuclear genome recoding. The population of guide RNAs directing editing is minimal, yet virtually all genes for the plethora of known editing factors are still present. Most intriguingly, despite lacking complex I cryptogene guide RNAs, these cryptogene transcripts are stochastically edited to high levels.

Charge Puddles Driven Complex Crossover of Magnetoresistance in Non-Topological Sulfur Doped Antimony Selenide Nanowires.

A race to achieve a crossover from positive to negative magnetoresistance is intense in the field of nanostructured materials to reduce the size of memory devices. Here, the unusual complex magnetoresistance in nonmagnetic sulfur-doped Sb2Se3nanowires is demonstrated. Intentionally, sulfur is doped in such a way to nearly achieve the charge neutrality point that is evident from switching of carrier type from p-type to n-type at 13 K as inferred from the low-temperature thermoelectric power measurements. A change from 3D variable range hopping (VRH) to power law transport with α = 0.18 in resistivity measurement signifies a Luttinger liquid transport with weak links through the nanowires. Interestingly, high magnetic field induced negative magnetoresistance (NMR) occurring in hole dominated temperature regimes can only be explained by invoking the concept of charge puddles. Spot energy dispersive spectroscopy (EDS), magnetic force microscopy (MFM) measurements, Tmottand Regel plot indicate an enhanced disorder in these sulfurized nanowires that are found to be the precursor for the formation of these charge puddles. Tunability of conducting states in these nanowires is investigated in the light of interplay of carrier type, magnetic field, temperature, and intricate intra-inter wire transport that makes this nanowires potential for large scale spintronic devices.

Unzipped genome assemblies of polyploid root-knot nematodes reveal unusual and clade-specific telomeric repeats

Using long-read sequencing, we assembled and unzipped the polyploid genomes of Meloidogyne incognita, M. javanica and M. arenaria, three of the most devastating plant-parasitic nematodes. We found the canonical nematode telomeric repeat to be missing in these and other Meloidogyne genomes. In addition, we find no evidence for the enzyme telomerase or for orthologs of C. elegans telomere-associated proteins, suggesting alternative lengthening of telomeres. Instead, analyzing our assembled genomes, we identify species-specific composite repeats enriched mostly at one extremity of contigs. These repeats are G-rich, oriented, and transcribed, similarly to canonical telomeric repeats. We confirm them as telomeric using fluorescent in situ hybridization. These repeats are mostly found at one single end of chromosomes in these species. The discovery of unusual and specific complex telomeric repeats opens a plethora of perspectives and highlights the evolutionary diversity of telomeres despite their central roles in senescence, aging, and chromosome integrity.

Architecture of Easy-to-Synthesize and Superior Probe Based on Aminoquinoline Appended Naphthoquinone: Instant and On-Site Cu2+ Ion Quantification in Real Samples and Unusual Crystal Structure and Logic Gate Operations.

Easy-to-synthesize aminoquinoline (AQ) appended naphthoquinone (NQ)-based colorimetric and ratiometric probe (AQNQ) was successfully synthesized in one step with high yield and low cost, and was utilized to supply an effective solution to critical shortcomings encountered in Cu2+ analysis. The structure of AQNQ and its interaction with Cu2+ forming an unusual AQNQ-Cu complex were enlightened with single-crystal X-ray diffraction analysis and different spectroscopic methods. AQNQ-Cu complex is the first Cu2+ containing dinuclear crystal where the octahedral coordination sphere is fulfilled through the coordination of a NQ oxygen atom. AQNQ exhibited long-term stability (more than 1 month), superior probe ability toward Cu2+ with quite fast response (30 s), high selectivity among many ions, and limit of detection of 12.13 ppb that is significantly below the highest amount of Cu2+ allowed in drinking water established by both WHO and EPA. Ratiometric determination of Cu2+ using AQNQ was performed with high recovery and low RSD values for drinking water, tap water, lake water, cherry, and watermelon samples. Colorimetric on-site determination including smartphone and paper strip applications, IMPLICATION, and INHIBIT logic gate applications were successfully carried out. The reversibility and reusability of the response to Cu2+ ions with the paper strip application were examined for the first time.

Tridentate NacNac Tames T-Shaped Nickel(I) Radical.

The reaction of a nickel(II) chloride complex containing a tridentate β-diketiminato ligand with a picolyl group [2,6-iPr2 -C6 H3 NC(Me)CHC(Me)NH(CH2 py)]Ni(II)Cl (1)] with KSi(SiMe3 )3 conveniently afforded a nickel(I) radical with a T-shaped geometry (2). The compound's metalloradical nature was confirmed through electron paramagnetic resonance (EPR) studies and its reaction with TEMPO, resulting in the formation of a highly unusual three-membered nickeloxaziridine complex (3). When reacted with disulfide and diselenide, the S-S and Se-Se bonds were cleaved, and a coupled product was formed through carbon atom of the pyridine-imine group. The nickel(I) radical activates dihydrogen at room temperature and atmospheric pressure to give the monomeric nickel hydride.

Superior mesenteric artery syndrome: A tough nut to crack – A rare complication in the management of oligometastatic colorectal carcinoma

The superior mesenteric artery (SMA) syndrome is a rare cause of intestinal obstruction. However, conditions associated with rapid weight loss, including malignancy, burns, bariatric surgery, and trauma, can precipitate the syndrome. Recognition of the syndrome requires a high index of suspicion and a multidisciplinary approach in conjunction with the radiologist. Here, we present the case of a patient with metastatic colon cancer, who developed symptoms of abdominal pain and hematuria after undergoing a local ablative procedure for liver metastases. He was extensively evaluated, in view of a history of abdominal pain in the supine position and relieved in the prone position, along with a history of similar complaints following an earlier colectomy procedure and a history of weight loss. In view of this unusual symptom complex coupled with the radiologic findings on the ultrasound, he underwent a barium swallow which showed duodenal dilation and a reduced aortomesenteric angle. Thus, a diagnosis of the SMA syndrome with the nutcracker phenomenon was made. The patient was managed conservatively and is on regular follow-up. The case highlights the need for a multidisciplinary approach, with an innocuous observation in tandem with the clinical history being pivotal in clinching a rare diagnosis.

An all-rounder aminoguanidine based ligand, its unusual anionic zinc(ii) and cadmium(ii) coordination complexes and their biological implications

The versatility of the ligand by protonating and deprotonating in the same medium yields unparallel complexes, one of which is more potent against E. coli than the standard ciprofloxacin, and opens-up new possibilities in coordination chemistry.

In situ studies of reversible solid-gas reactions of ethylene responsive silver pyrazolates.

Solid-gas reactions and in situ powder X-ray diffraction investigations of trinuclear silver complexes {[3,4,5-(CF3)3Pz]Ag}3 and {[4-Br-3,5-(CF3)2Pz]Ag}3 supported by highly fluorinated pyrazolates reveal that they undergo intricate ethylene-triggered structural transformations in the solid-state producing dinuclear silver-ethylene adducts. Despite the complexity, the chemistry is reversible producing precursor trimers with the loss of ethylene. Less reactive {[3,5-(CF3)2Pz]Ag}3 under ethylene pressure and low-temperature conditions stops at an unusual silver-ethylene complex in the trinuclear state, which could serve as a model for intermediates likely present in more common trimer-dimer reorganizations described above. Complete structural data of three novel silver-ethylene complexes are presented together with a thorough computational analysis of the mechanism.