Cobalt-Mediated Photochemical C-H Arylation of Pyrroles.

Precious metal complexes remain ubiquitous in photoredox catalysis (PRC) despite concerted efforts to find more earth-abundant catalysts and replacements based on 3d metals in particular. Most otherwise plausible 3d metal complexes are assumed to be unsuitable due to short-lived excited states, which has led researchers to prioritize the pursuit of longer excited-state lifetimes through careful molecular design. However, we report herein that the C-H arylation of pyrroles and related substrates (which are benchmark reactions for assessing the efficacy of photoredox catalysts) can be achieved using a simple and readily accessible octahedral bis(diiminopyridine) cobalt complex, [1-Co](PF6)2. Notably, [1-Co]2+ efficiently functionalizes both chloro- and bromoarene substrates despite the short excited-state lifetime of the key photoexcited intermediate *[1-Co]2+ (8 ps). We present herein the scope of this C-H arylation protocol and provide mechanistic insights derived from detailed spectroscopic and computational studies. These indicate that, despite its transient existence, reduction of *[1-Co]2+ is facilitated via pre-assembly with the NEt3 reductant, highlighting an alternative strategy for the future development of 3d metal-catalyzed PRC.

Deficiency in Galectin-3, -8, and -9 impairs immunity to chronic Mycobacterium tuberculosis infection but not acute infection with multiple intracellular pathogens.

Macrophages employ an array of pattern recognition receptors to detect and eliminate intracellular pathogens that access the cytosol. The cytosolic carbohydrate sensors Galectin-3, -8, and -9 (Gal-3, Gal-8, and Gal-9) recognize damaged pathogen-containing phagosomes, and Gal-3 and Gal-8 are reported to restrict bacterial growth via autophagy in cultured cells. However, the contribution of these galectins to host resistance during bacterial infection in vivo remains unclear. We found that Gal-9 binds directly to Mycobacterium tuberculosis (Mtb) and Salmonella enterica serovar Typhimurium (Stm) and localizes to Mtb in macrophages. To determine the combined contribution of membrane damage-sensing galectins to immunity, we generated Gal-3, -8, and -9 triple knockout (TKO) mice. Mtb infection of primary macrophages from TKO mice resulted in defective autophagic flux but normal bacterial replication. Surprisingly, these mice had no discernable defect in resistance to acute infection with Mtb, Stm or Listeria monocytogenes, and had only modest impairments in bacterial growth restriction and CD4 T cell activation during chronic Mtb infection. Collectively, these findings indicate that while Gal-3, -8, and -9 respond to an array of intracellular pathogens, together these membrane damage-sensing galectins play a limited role in host resistance to bacterial infection.

Autophagy restricts Mycobacterium tuberculosis during acute infection in mice.

Whether or not autophagy has a role in defence against Mycobacterium tuberculosis infection remains unresolved. Previously, conditional knockdown of the core autophagy component ATG5 in myeloid cells was reported to confer extreme susceptibility to M. tuberculosis in mice, whereas depletion of other autophagy factors had no effect on infection. We show that doubling cre gene dosage to more robustly deplete ATG16L1 or ATG7 resulted in increased M. tuberculosis growth and host susceptibility in mice, although ATG5-depleted mice are more sensitive than ATG16L1- or ATG7-depleted mice. We imaged individual macrophages infected with M. tuberculosis and identified a shift from apoptosis to rapid necrosis in autophagy-depleted cells. This effect was dependent on phagosome permeabilization by M. tuberculosis. We monitored infected cells by electron microscopy, showing that autophagy protects the host macrophage by partially reducing mycobacterial access to the cytosol. We conclude that autophagy has an important role in defence against M. tuberculosis in mammals.

Distinct Energy-Coupling Factor Transporter Subunits Enable Flavin Acquisition and Extracytosolic Trafficking for Extracellular Electron Transfer in Listeria monocytogenes.

A variety of electron transfer mechanisms link bacterial cytosolic electron pools with functionally diverse redox activities in the cell envelope and extracellular space. In Listeria monocytogenes, the ApbE-like enzyme FmnB catalyzes extracytosolic protein flavinylation, covalently linking a flavin cofactor to proteins that transfer electrons to extracellular acceptors. L. monocytogenes uses an energy-coupling factor (ECF) transporter complex that contains distinct substrate-binding, transmembrane, ATPase A, and ATPase A' subunits (RibU, EcfT, EcfA, and EcfA') to import environmental flavins, but the basis of extracytosolic flavin trafficking for FmnB flavinylation remains poorly defined. In this study, we show that the EetB and FmnA proteins are related to ECF transporter substrate-binding and transmembrane subunits, respectively, and are essential for exporting flavins from the cytosol for flavinylation. Comparisons of the flavin import versus export capabilities of L. monocytogenes strains lacking different ECF transporter subunits demonstrate a strict directionality of substrate-binding subunit transport but partial functional redundancy of transmembrane and ATPase subunits. Based on these results, we propose that ECF transporter complexes with different subunit compositions execute directional flavin import/export through a broadly conserved mechanism. Finally, we present genomic context analyses that show that related ECF exporter genes are distributed across members of the phylum Firmicutes and frequently colocalize with genes encoding flavinylated extracytosolic proteins. These findings clarify the basis of ECF transporter export and extracytosolic flavin cofactor trafficking in Firmicutes. IMPORTANCE Bacteria import vitamins and other essential compounds from their surroundings but also traffic related compounds from the cytosol to the cell envelope where they serve various functions. Studying the foodborne pathogen Listeria monocytogenes, we find that the modular use of subunits from a prominent class of bacterial transporters enables the import of environmental vitamin B2 cofactors and the extracytosolic trafficking of a vitamin B2-derived cofactor that facilitates redox reactions in the cell envelope. These studies clarify the basis of bidirectional small-molecule transport across the cytoplasmic membrane and the assembly of redox-active proteins within the cell envelope and extracellular space.

Reduction of Nitrous Oxide by Light Alcohols Catalysed by a Low-Valent Ruthenium Diazadiene Complex.

Decomposition of the environmentally harmful gas nitrous oxide (N2 O) is usually performed thermally or catalytically. Selective catalytic reduction (SCR) is currently the most promising technology for N2 O mitigation, a multicomponent heterogeneous catalytic system that employs reducing agents such as ammonia, hydrogen, hydrocarbons, or a combination thereof. This study reports the first homogenous catalyst that performs the reduction of nitrous oxide employing readily available and cheap light alcohols such as methanol, ethanol or ethylene glycol derivatives. During the reaction, these alcohols are transformed in a dehydrogenative coupling reaction to carboxylate derivatives, while N2 O is converted to N2 and H2 O, later entering the reaction as substrate. The reaction is catalysed by the low-valent dinuclear ruthenium complex [Ru2 H(µ-H)(Me2 dad)(dbcot)2 ] that carries a diazabutadiene, Me2 dad, and two rigid dienes, dbcot, as ligands. The reduction of nitrous oxide proceeds with low catalyst loadings under relatively mild conditions (65-80 °C, 1.4 bar N2 O) achieving turnover numbers of up to 480 and turnover frequencies of up to 56 h-1 .

Listeria monocytogenes requires cellular respiration for NAD+ regeneration and pathogenesis.

Cellular respiration is essential for multiple bacterial pathogens and a validated antibiotic target. In addition to driving oxidative phosphorylation, bacterial respiration has a variety of ancillary functions that obscure its contribution to pathogenesis. We find here that the intracellular pathogen Listeria monocytogenes encodes two respiratory pathways which are partially functionally redundant and indispensable for pathogenesis. Loss of respiration decreased NAD+ regeneration, but this could be specifically reversed by heterologous expression of a water-forming NADH oxidase (NOX). NOX expression fully rescued intracellular growth defects and increased L. monocytogenes loads >1000-fold in a mouse infection model. Consistent with NAD+ regeneration maintaining L. monocytogenes viability and enabling immune evasion, a respiration-deficient strain exhibited elevated bacteriolysis within the host cytosol and NOX expression rescued this phenotype. These studies show that NAD+ regeneration represents a major role of L. monocytogenes respiration and highlight the nuanced relationship between bacterial metabolism, physiology, and pathogenesis.

Cellular respiration is one of the main ways organisms make energy. It works by linking the oxidation of an electron donor (like sugar) to the reduction of an electron acceptor (like oxygen). Electrons pass between the two molecules along what is known as an 'electron transport chain'. This process generates a force that powers the production of adenosine triphosphate (ATP), a molecule that cells use to store energy. Respiration is a common way for cells to replenish their energy stores, but it is not the only way. A simpler process that does not require a separate electron acceptor or an electron transport chain is called fermentation. Many bacteria have the capacity to perform both respiration and fermentation and do so in a context-dependent manner. Research has shown that respiration can contribute to bacterial diseases, like tuberculosis and listeriosis (a disease caused by the foodborne pathogen Listeria monocytogenes). Indeed, some antibiotics even target bacterial respiration. Despite being often discussed in the context of generating ATP, respiration is also important for many other cellular processes, including maintaining the balance of reduced and oxidized nicotinamide adenine dinucleotide (NAD) cofactors. Because of these multiple functions, the exact role respiration plays in disease is unknown. To find out more, Rivera-Lugo, Deng et al. developed strains of the bacterial pathogen Listeria monocytogenes that lacked some of the genes used in respiration. The resulting bacteria were still able to produce energy, but they became much worse at infecting mammalian cells. The use of a genetic tool that restored the balance of reduced and oxidized NAD cofactors revived the ability of respiration-deficient L. monocytogenes to infect mammalian cells, indicating that this balance is what the bacterium requires to infect. Research into respiration tends to focus on its role in generating ATP. But these results show that for some bacteria, this might not be the most important part of the process. Understanding the other roles of respiration could change the way that researchers develop antibacterial drugs in the future. This in turn could help with the growing problem of antibiotic resistance.

RibU is an essential determinant of Listeria pathogenesis that mediates acquisition of FMN and FAD during intracellular growth.

Flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) are essential riboflavin-derived cofactors involved in a myriad of redox reactions across all forms of life. Nevertheless, the basis of flavin acquisition strategies by riboflavin auxotrophic pathogens remains poorly defined. In this study, we examined how the facultative intracellular pathogen Listeria monocytogenes, a riboflavin auxotroph, acquires flavins during infection. A L. monocytogenes mutant lacking the putative riboflavin transporter (RibU) was completely avirulent in mice but had no detectable growth defect in nutrient-rich media. However, unlike wild type, the RibU mutant was unable to grow in defined media supplemented with FMN or FAD or to replicate in macrophages starved for riboflavin. Consistent with RibU functioning to scavenge FMN and FAD inside host cells, a mutant unable to convert riboflavin to FMN or FAD retained virulence and grew in cultured macrophages and in spleens and livers of infected mice. However, this FMN- and FAD-requiring strain was unable to grow in the gallbladder or intestines, where L. monocytogenes normally grows extracellularly, suggesting that these sites do not contain sufficient flavin cofactors to promote replication. Thus, by deleting genes required to synthesize FMN and FAD, we converted L. monocytogenes from a facultative to an obligate intracellular pathogen. Collectively, these data indicate that L. monocytogenes requires riboflavin to grow extracellularly in vivo but scavenges FMN and FAD to grow in host cells.

Unusual toxic accident caused by Calosoma alternans, Fabricius 1792 (Coleoptera: Carabidae) in a Venezuelan patient / Accidente tóxico inusual provocado por Calosoma alternans, Fabricius 1792 (Coleoptera: Carabidae) en un paciente venezolano

Coleopteran insects can produce toxic substances containing multiple components which have so far not been properly described. To report an unusual case of intoxication by excretion from Calosoma alternans Fabricius 1792 (Coleoptera: Carabidae) in a Venezuelan patient from a periurban neighborhood near the mesothermal raining forest. The toxic activity caused a clinical status characterized by digestive symptoms such as nausea, vomiting, epigastralgia, an increase in bowel movements and probable kidney inflammation with intense pain in both lumbar regions, which did not correspond to the classic dermal damage. In conclusion, a unique case is presented of intoxication by a coleopteran species, with a clinical description not previously reported(AU)

Los insectos coleópteros pueden producir sustancias tóxicas que contienen numerosos componentes que aún no han sido descritos adecuadamente. Presentar un caso inusual de intoxicación por excreciones de Calosoma alternans Fabricius 1792 (Coleoptera: Carabidae) en un paciente venezolano residente en un barrio periurbano cercano a la selva tropical mesotérmica. La actividad tóxica provocó un cuadro clínico caracterizado por síntomas digestivos como náuseas, vómitos, epigastralgia, aumento del número de deposiciones y probablemente inflamación renal, con dolor intenso en ambas regiones lumbares, lo que no se corresponde con el daño dérmico clásico. En resumen, se presenta un caso singular de intoxicación provocada por una especie de coleóptero, con una descripción clínica no reportada anteriormente(AU)

Post-translational flavinylation is associated with diverse extracytosolic redox functionalities throughout bacterial life.

Disparate redox activities that take place beyond the bounds of the prokaryotic cell cytosol must connect to membrane or cytosolic electron pools. Proteins post-translationally flavinylated by the enzyme ApbE mediate electron transfer in several characterized extracytosolic redox systems but the breadth of functions of this modification remains unknown. Here, we present a comprehensive bioinformatic analysis of 31,910 prokaryotic genomes that provides evidence of extracytosolic ApbEs within ~50% of bacteria and the involvement of flavinylation in numerous uncharacterized biochemical processes. By mining flavinylation-associated gene clusters, we identify five protein classes responsible for transmembrane electron transfer and two domains of unknown function (DUF2271 and DUF3570) that are flavinylated by ApbE. We observe flavinylation/iron transporter gene colocalization patterns that implicate functions in iron reduction and assimilation. We find associations with characterized and uncharacterized respiratory oxidoreductases that highlight roles of flavinylation in respiratory electron transport chains. Finally, we identify interspecies gene cluster variability consistent with flavinylation/cytochrome functional redundancies and discover a class of 'multi-flavinylated proteins' that may resemble multi-heme cytochromes in facilitating longer distance electron transfer. These findings provide mechanistic insight into an important facet of bacterial physiology and establish flavinylation as a functionally diverse mediator of extracytosolic electron transfer.

In bacteria, certain chemical reactions required for life do not take place directly inside the cells. For instance, 'redox' reactions essential to gather minerals, repair proteins and obtain energy are localised in the membranes and space that surround a bacterium. These chemical reactions involve electrons being transferred from one molecule to another in a cascade that connects the exterior of a cell to its internal space. The enzyme ApbE allows proteins to perform electron transfer by equipping them with ring-like compounds called flavins, through a process known as flavinylation. Yet, the prevelance of flavinylation in bacteria and the scope of redox reactions it facilitates has remained unclear. To investigate this question, Méheust, Huang et al. analysed over 30,000 bacterial genomes, finding genes essential for ApbE flavinylation in about half of all bacterial species across the tree of life. The role of ApbE-flavinylated proteins was then deciphered using a 'guilt by association' approach. In bacteria, genes that perform similar roles are often close to each other in the genome, which helps to infer the function of a protein coded by a specific gene. This approach revealed that flavinylation is involved in processes that allow bacteria to acquire iron and to use various energy sources. A number of interesting proteins were also identified, including a group that carry multiple flavins, and could therefore, in theory, transfer electrons over long distances. This discovery could be relevant to bioelectronic applications, which are already considering another class of bacterial electron-carrying molecules as candidates to form minuscule electric wires.

Artificial Triterpenoid Fatty Acid Ester Isolated From the Leaves of Phytolacca icosandra L.

The methanol extract form the leaves of Phytolacca icosandra L., afforded the unprecedented artificial triterpenoid fatty acid ester 1 derived from the new natural triterpenoid phytolaccagenic acid 3-O-myristate (1a), along with the three known triterpenoids serjanic, acinosolic and phytolaccagenic acid (2 - 4). Their structures were stablished by HR-EI-MS, 1D and 2D NMR techniques. The possible mechanistic formation of 1 is proposed, and the in vitro toxicity of all compounds was assessed using the brine shrimp lethality assay (BSLA).

Relación entre estrés percibido y calidad de sueño en enfermeras de turnos nocturno y rotativo / Relationship between perceived stress and sleep quality in night-shift and rotating nurses

Objetivo: determinar si existe relación entre el estrés percibido y la calidad de sueño en las enfermeras de los turnos nocturno y rotativo de la empresa social del Estado Hospital San Rafael de Facatativá. Metodología: estudio transversal con alcance correlacional donde se evaluó el estrés percibido y la calidad de sueño por medio de la escala de estrés percibido - versión 14 y el índice de calidad de sueño de Pittsburg -versión colombiana, respectivamente, en una muestra de 98 enfermeras que cumplieron con los criterios de inclusión. Resultados: se presentó una prevalencia del 72,45% de estrés percibido y del 79,59% de mala calidad de sueño; entre estas dos variables se halló una correlación baja (r=0,258; p=0,010). Se puede asegur ar con un 95 % de confianza que mientras una variable aumenta, la otra también lo hace, queriendo decir que a mayor puntaje en la escala de estrés percibido, mayor puntaje en el índice de calidad de sueño de Pittsburgh, lo que sugiere que el nivel de estrés es un factor que tiene relación directamente proporcional con el sueño, es decir, entre mayor estrés, peor calidad de sueño. Conclusiones: se concluye que sí existe relación entre el estrés percibido y la calidad de sueño, lo cual evidencia, por un lado, que en las enfermeras a mayor estrés, peor calidad de sueño, y por otro, que a peor calidad de sueño, mayor estrés.

Objective: To determine if there is a relationship between perceived stress and sleep quality in nurses in the night and rotating shifts of the social enterprise of the State Hospital San Rafael of Facatativá. Methodology: Study cross-sectional with a correlational scope where the perceived stress was assessed through the Perceived Stress Scale, Version 14, and sleep quality using the Pittsburg Sleep Quality Index, Colombian Version, in a sample of 98 nurses who met the inclusion criteria. Results: a prevalence of 72.45% of stress and 79.59% of poor sleep quality were perceived; there was a low correlation between these two variables (r= 0.258; p=0.010). It may be ensured with 95% of confidence that while a variable increases, the other one does the same; this means that higher stress level in the perceived stress scale implies a higher score in the Pittsburgh Sleep Quality Index; which suggests that stress level is a factor that has directly proportional relationship with sleep; so, higher stress level is equal to worse sleep quality. Conclusions: It is concluded that there is a relationship between perceived stress and sleep quality, showing that, the greater the stress in the nurses, the worse the quality of sleep, as well as the worse the quality of sleep, the greater the stress

A flavin-based extracellular electron transfer mechanism in diverse Gram-positive bacteria.

Extracellular electron transfer (EET) describes microbial bioelectrochemical processes in which electrons are transferred from the cytosol to the exterior of the cell1. Mineral-respiring bacteria use elaborate haem-based electron transfer mechanisms2-4 but the existence and mechanistic basis of other EETs remain largely unknown. Here we show that the food-borne pathogen Listeria monocytogenes uses a distinctive flavin-based EET mechanism to deliver electrons to iron or an electrode. By performing a forward genetic screen to identify L. monocytogenes mutants with diminished extracellular ferric iron reductase activity, we identified an eight-gene locus that is responsible for EET. This locus encodes a specialized NADH dehydrogenase that segregates EET from aerobic respiration by channelling electrons to a discrete membrane-localized quinone pool. Other proteins facilitate the assembly of an abundant extracellular flavoprotein that, in conjunction with free-molecule flavin shuttles, mediates electron transfer to extracellular acceptors. This system thus establishes a simple electron conduit that is compatible with the single-membrane structure of the Gram-positive cell. Activation of EET supports growth on non-fermentable carbon sources, and an EET mutant exhibited a competitive defect within the mouse gastrointestinal tract. Orthologues of the genes responsible for EET are present in hundreds of species across the Firmicutes phylum, including multiple pathogens and commensal members of the intestinal microbiota, and correlate with EET activity in assayed strains. These findings suggest a greater prevalence of EET-based growth capabilities and establish a previously underappreciated relevance for electrogenic bacteria across diverse environments, including host-associated microbial communities and infectious disease.

No Evidence for the Pathogenicity of the BRCA2 c.6937 + 594T>G Deep Intronic Variant: A Case-Control Analysis.

BACKGROUND: The role of deep intronic variants in hereditary cancer susceptibility has been largely understudied. Previously, the BRCA2 c.6937 + 594T>G variant has been shown to preferentially promote the inclusion of a 95 nucleotide cryptic exon and to introduce a premature termination codon. Our objective was to further assess the pathogenicity of the BRCA2 c.6937 + 594T>G deep intronic variant. PATIENTS AND METHODS: We examined the association between BRCA2 c.6937 + 594T>G and breast cancer (BC) risk in 464 BC cases and 497 noncancer controls from Puerto Rico. RESULTS: The overall frequency of the G allele was 2.1% in this population. There was no association between the TG/GG genotypes and BC risk in the uncorrected model and after correcting for confounders. There was only one carrier of the GG genotype. This individual did not have personal or family history of cancer and did not meet the National Comprehensive Cancer Network criteria for hereditary cancer genetic testing. CONCLUSIONS: Although previous work has demonstrated that the BRCA2 c.6937 + 594T>G variant affects splicing, this association study does not support a pathogenic role for the BRCA2 c.6937 + 594T>G intronic variant in breast and ovarian cancer syndrome susceptibility. Furthermore, it emphasizes the need to take into account multiple diverse populations in association studies for the assessment of variant pathogenicity.

Homogeneously catalysed conversion of aqueous formaldehyde to H2 and carbonate.

Small organic molecules provide a promising solution for the requirement to store large amounts of hydrogen in a future hydrogen-based energy system. Herein, we report that diolefin-ruthenium complexes containing the chemically and redox non-innocent ligand trop2dad catalyse the production of H2 from formaldehyde and water in the presence of a base. The process involves the catalytic conversion to carbonate salt using aqueous solutions and is the fastest reported for acceptorless formalin dehydrogenation to date. A mechanism supported by density functional theory calculations postulates protonation of a ruthenium hydride to form a low-valent active species, the reversible uptake of dihydrogen by the ligand and active participation of both the ligand and the metal in substrate activation and dihydrogen bond formation.

A Stable Aminyl Radical Coordinated to Cobalt.

A family of cobalt complexes bearing the trop2 NH [bis(5-H-dibenzo[a,d]cyclohepten-5-yl)-amine] and 2,2'-bpy (2,2'-bipyridine) chelate ligands were prepared and fully characterized. The compounds [Co(trop2 N)(bpy)], [Co(trop2 NH)(bpy)]+ , and [Co(trop2 N)(bpy)]+ are cobalt complexes interrelated by one-electron redox processes and/or proton transfer. Two limiting resonance structures can be used to describe the paramagnetic complex [Co(trop2 N)(bpy)]+ : [CoII (trop2 N- )(bpy)]+ (CoII amido) and [CoI (trop2 N⋅ )(bpy)]+ (CoI -aminyl radical). Structural data, DFT calculations, and reactivity toward H-abstraction indicate a slightly higher contribution of the aminyl radical form to the ground state of [Co(trop2 N)(bpy)]+ . The results described here complete the series of Group 9 metal aminyl radical complexes bearing the diolefin amine ligand trop2 NH.

Zero-Valent Amino-Olefin Cobalt Complexes as Catalysts for Oxygen Atom Transfer Reactions from Nitrous Oxide.

The synthesis and characterization of several zero-valent cobalt complexes with a bis(olefin)-amino ligand is presented. Some of these complexes proved to be efficient catalysts for the selective oxidation of secondary and allylic phosphanes, as well as diphosphanes, even with a direct P-P bond. With 5 mol % catalyst loadings the oxidations proceed under mild conditions (25-70 °C, 7-22 h, 2 bar N2 O) and afford good to excellent yields (65-98 %). In this process, the greenhouse gas N2 O is catalytically converted into benign N2 and added-value organophosphorus compounds, some of which are difficult to obtain otherwise.

Insights into metal-ligand hydrogen transfer: a square-planar ruthenate complex supported by a tetradentate amino-amido-diolefin ligand.

A four-coordinate, sixteen-electron Ru(0) complex containing the tetradentate diamino-diolefin ligand (±)-trans-N,N-bis(5H-dibenzo[a,d]cyclohepten-5-yl)-1,2-diaminocyclohexane (trop2dach) has been synthesised. Deprotonation of one amino N-H functional group generates an unprecedented four-coordinate ruthenate species which has been characterised in solution and in the solid state. The newly formed ruthenate complex undergoes intramolecular metal-ligand N-H addition/elimination in solution to generate a transient diamido ruthenium hydride species, as supported by NMR spectroscopy and density functional theory.

A non-additive repulsive contribution in an equation of state: The development for homonuclear square well chains equation of state validated against Monte Carlo simulation.

This work consists of the adaptation of a non-additive hard sphere theory inspired by Malakhov and Volkov [Polym. Sci., Ser. A 49(6), 745-756 (2007)] to a square-well chain. Using the thermodynamic perturbation theory, an additional term is proposed that describes the effect of perturbing the chain of square well spheres by a non-additive parameter. In order to validate this development, NPT Monte Carlo simulations of thermodynamic and structural properties of the non-additive square well for a pure chain and a binary mixture of chains are performed. Good agreements are observed between the compressibility factors originating from the theory and those from molecular simulations.

The solid-state emmissive chalcone (2E)-1-(5-chlorothiophen-2-yl)-3-[4-(dimethylamino)phenyl]prop-2-en-1-one.

Orange rectangular blocks suitable for X-ray diffraction analysis were obtained for the previously reported [Ahmad & Bano (2011). Int. J. ChemTech Res. 3, 1470-1478] title chalcone, C15H14ClNOS. This solid-emissive chalcone exhibits a planar structure and the bond parameters are compared with related compounds already described in the literature. The determination of the structure of this chalcone is quite relevant because it will play an important role in theoretical calculations to investigate potential two-photon absorption processes and could also be useful for studying the interaction of such compounds with a biological target.