Tailoring the Photophysical Properties of a Homoleptic Iron(II) Tetra N-Heterocyclic Carbene Complex by Attaching an Imidazolium Group to the (C∧N∧C) Pincer Ligand─A Comparative Study.

We here report the synthesis of the homoleptic iron(II) N-heterocyclic carbene (NHC) complex [Fe(miHpbmi)2](PF6)4 (miHpbmi = 4-((3-methyl-1H-imidazolium-1-yl)pyridine-2,6-diyl)bis(3-methylimidazol-2-ylidene)) and its electrochemical and photophysical properties. The introduction of the π-electron-withdrawing 3-methyl-1H-imidazol-3-ium-1-yl group into the NHC ligand framework resulted in stabilization of the metal-to-ligand charge transfer (MLCT) state and destabilization of the metal-centered (MC) states. This resulted in an improved excited-state lifetime of 16 ps compared to the 9 ps for the unsubstituted parent compound [Fe(pbmi)2](PF6)2 (pbmi = (pyridine-2,6-diyl)bis(3-methylimidazol-2-ylidene)) as well as a stronger MLCT absorption band extending more toward the red spectral region. However, compared to the carboxylic acid derivative [Fe(cpbmi)2](PF6)2 (cpbmi = 1,1'-(4-carboxypyridine-2,6-diyl)bis(3-methylimidazol-2-ylidene)), the excited-state lifetime of [Fe(miHpbmi)2](PF6)4 is the same, but both the extinction and the red shift are more pronounced for the former. Hence, this makes [Fe(miHpbmi)2](PF6)4 a promising pH-insensitive analogue of [Fe(cpbmi)2](PF6)2. Finally, the excited-state dynamics of the title compound [Fe(miHpbmi)2](PF6)4 was investigated in solvents with different viscosities, however, showing very little dependency of the depopulation of the excited states on the properties of the solvent used.

How Rigidity and Conjugation of Bidentate Ligands Affect the Geometry and Photophysics of Iron N-Heterocyclic Complexes: A Comparative Study.

Two iron complexes featuring the bidentate, nonconjugated N-heterocyclic carbene (NHC) 1,1'-methylenebis(3-methylimidazol-2-ylidene) (mbmi) ligand, where the two NHC moieties are separated by a methylene bridge, have been synthesized to exploit the combined influence of geometric and electronic effects on the ground- and excited-state properties of homoleptic FeIII-hexa-NHC [Fe(mbmi)3](PF6)3 and heteroleptic FeII-tetra-NHC [Fe(mbmi)2(bpy)](PF6)2 (bpy = 2,2'-bipyridine) complexes. They are compared to the reported FeIII-hexa-NHC [Fe(btz)3](PF6)3 and FeII-tetra-NHC [Fe(btz)2(bpy)](PF6)2 complexes containing the conjugated, bidentate mesoionic NHC ligand 3,3'-dimethyl-1,1'-bis(p-tolyl)-4,4'-bis(1,2,3-triazol-5-ylidene) (btz). The observed geometries of [Fe(mbmi)3](PF6)3 and [Fe(mbmi)2(bpy)](PF6)2 are evaluated through L-Fe-L bond angles and ligand planarity and compared to those of [Fe(btz)3](PF6)3 and [Fe(btz)2(bpy)](PF6)2. The FeII/FeIII redox couples of [Fe(mbmi)3](PF6)3 (-0.38 V) and [Fe(mbmi)2(bpy)](PF6)2 (-0.057 V, both vs Fc+/0) are less reducing than [Fe(btz)3](PF6)3 and [Fe(btz)2(bpy)](PF6)2. The two complexes show intense absorption bands in the visible region: [Fe(mbmi)3](PF6)3 at 502 nm (ligand-to-metal charge transfer, 2LMCT) and [Fe(mbmi)2(bpy)](PF6)2 at 410 and 616 nm (metal-to-ligand charge transfer, 3MLCT). Lifetimes of 57.3 ps (2LMCT) for [Fe(mbmi)3](PF6)3 and 7.6 ps (3MLCT) for [Fe(mbmi)2(bpy)](PF6)2 were probed and are somewhat shorter than those for [Fe(btz)3](PF6)3 and [Fe(btz)2(bpy)](PF6)2. [Fe(mbmi)3](PF6)3 exhibits photoluminescence at 686 nm (2LMCT) in acetonitrile at room temperature with a quantum yield of (1.2 ± 0.1) × 10-4, compared to (3 ± 0.5) × 10-4 for [Fe(btz)3](PF6)3.

Characterization of Alternaria blotch disease of apple in Himachal Pradesh, India: insights on morphology, pathogenicity, and molecular features.

BACKGROUND: Alternaria blotch disease in Himachal Pradesh, India, caused by Alternaria spp., adversely affects apple cultivars, resulting in reduced fruit size and quality accompanied by premature leaf fall. METHODS AND RESULTS: Sixteen Alternaria isolates from apple growing regions underwent comprehensive analysis including morphology, pathogenicity, and molecular characterization. Variations in conidiophore and conidia dimensions, shapes, and divisions were observed among isolates. Pathogenicity assays revealed differences in incubation periods, latent phases, and disease responses. Molecular characterization via nuclear ITS rDNA and RAPD analysis indicated 99-100% homology with Alternaria alternata, Alternaria mali, and other Alternaria spp., with a close phylogenetic relationship to Chinese isolates. Differentiation of isolates based on origin, cultural characteristics, and morphology was achieved using RAPD markers. CONCLUSIONS: The study identifies diverse genotypes and morphotypes of Alternaria contributing to apple blotch disease in Himachal Pradesh. These findings highlight the complexity of the pathogenic environment and hold significant implications for disease management in apple orchards.

Photophysical Integrity of the Iron(III) Scorpionate Framework in Iron(III)-NHC Complexes with Long-Lived 2LMCT Excited States.

Fe(III) complexes with N-heterocyclic carbene (NHC) ligands belong to the rare examples of Earth-abundant transition metal complexes with long-lived luminescent charge-transfer excited states that enable applications as photosensitizers for charge separation reactions. We report three new hexa-NHC complexes of this class: [Fe(brphtmeimb)2]PF6 (brphtmeimb = [(4-bromophenyl)tris(3-methylimidazol-2-ylidene)borate]-, [Fe(meophtmeimb)2]PF6 (meophtmeimb = [(4-methoxyphenyl)tris(3-methylimidazol-2-ylidene)borate]-, and [Fe(coohphtmeimb)2]PF6 (coohphtmeimb = [(4-carboxyphenyl)tris(3-methylimidazol-2-ylidene)borate]-. These were derived from the parent complex [Fe(phtmeimb)2]PF6 (phtmeimb = [phenyltris(3-methylimidazol-2-ylidene)borate]- by modification with electron-withdrawing and electron-donating substituents, respectively, at the 4-phenyl position of the ligand framework. All three Fe(III) hexa-NHC complexes were characterized by NMR spectroscopy, high-resolution mass spectroscopy, elemental analysis, single crystal X-ray diffraction analysis, electrochemistry, Mößbauer spectroscopy, electronic spectroscopy, magnetic susceptibility measurements, and quantum chemical calculations. Their ligand-to-metal charge-transfer (2LMCT) excited states feature nanosecond lifetimes (1.6-1.7 ns) and sizable emission quantum yields (1.7-1.9%) through spin-allowed transition to the doublet ground state (2GS), completely in line with the parent complex [Fe(phtmeimb)2]PF6 (2.0 ns and 2.1%). The integrity of the favorable excited state characteristics upon substitution of the ligand framework demonstrates the robustness of the scorpionate motif that tolerates modifications in the 4-phenyl position for applications such as the attachment in molecular or hybrid assemblies.

Reference intervals for reticulocyte parameters (reticulocyte haemoglobin equivalent and immature reticulocyte fraction) in first-trimester pregnancy.

Reticulocyte parameters including reticulocyte haemoglobin equivalent (Ret-He) and immature reticulocyte fraction (IRF) are newly recognised hematological parameters that are being used for diagnosis and follow-up of anaemic patients. Reference intervals of these parameters have been established in different populations, however, the data relating to pregnancy are still lacking. One hundred and fifty-five first-trimester pregnant females were screened and the reference interval was calculated after selecting the patient with fixed criteria. R statistical software was used for statistical calculations. We tried to establish a reference interval of Ret-He content and IRF in first-trimester pregnancy in our study.IMPACT STATEMENTWhat is already known on this subject? Ret-He and IRF have been established as the marker of iron deficiency and iron-deficiency anaemia in different age groups and as a marker of response to iron therapy. However, literature is scarce regarding the reference intervals of these parameters, especially in pregnancy.What do the results of this study add? This study establishes the reference interval of newer reticulocyte parameters in first-trimester pregnancy which is not yet established in the literature. Establishing a reference interval is required for any laboratory parameters to be used in the clinical context.What are the implications of these findings for clinical practice and further research? The results of this study may help in making a clinical decision regarding iron deficiency in early pregnancy which is one of the common clinical problems in pregnancy. This study also serves as a baseline study for further studies of reference intervals for newer reticulocyte parameters in pregnancy. A similar study with a larger study population and follow-up with iron therapy may establish these parameters as one of the important markers of iron deficiency in pregnancy and help institute iron therapy on case-to-case basis.

Oxygenated Cyclohexene Derivatives from the Stem and Root Barks of Uvaria pandensis.

Five new cyclohexene derivatives, dipandensin A and B (1 and 2) and pandensenols A-C (3-5), and 16 known secondary metabolites (6-21) were isolated from the methanol-soluble extracts of the stem and root barks of Uvaria pandensis. The structures were characterized by NMR spectroscopic and mass spectrometric analyses, and that of 6-methoxyzeylenol (6) was further confirmed by single-crystal X-ray crystallography, which also established its absolute configuration. The isolated metabolites were evaluated for antibacterial activity against the Gram-positive bacteria Bacillus subtilis and Staphylococcus epidermidis and the Gram-negative bacteria Enterococcus raffinosus, Escherichia coli, Paraburkholderia caledonica, Pectobacterium carotovorum, and Pseudomonas putida, as well as for cytotoxicity against the MCF-7 human breast cancer cell line. A mixture of uvaretin (20) and isouvaretin (21) exhibited significant antibacterial activity against B. subtilis (EC50 8.7 µM) and S. epidermidis (IC50 7.9 µM). (8'α,9'ß-Dihydroxy)-3-farnesylindole (12) showed strong inhibitory activity (EC50 9.8 µM) against B. subtilis, comparable to the clinical reference ampicillin (EC50 17.9 µM). None of the compounds showed relevant cytotoxicity against the MCF-7 human breast cancer cell line.

Spatial network based model forecasting transmission and control of COVID-19.

The SARS-CoV-2 driven infectious novel coronavirus disease (COVID-19) has been declared a pandemic by its brutal impact on the world in terms of loss on human life, health, economy, and other crucial resources. To explore more about its aspects, we adopted the S E I R D (Susceptible-Exposed-Infected-Recovered-Death) pandemic spread with a time delay on the heterogeneous population and geography in this work. Focusing on the spatial heterogeneity, epidemic spread on the framework of modeling that incorporates population movement within and across the boundaries is studied. The entire population of interest in a region is divided into small distinct geographical sub regions, which interact using migration networks across boundaries. Utilizing the time delay differential equations based model estimations, we analyzed the spread dynamics of disease in India. The numerical outcomes from the model are validated using real time available data for COVID-19 cases. Based on the developed model in the framework of the recent data, we verified total infection cases in India considering the effect of nationwide lockdown at the onset of the pandemic and its unlocking by what seemed to be the end of the first wave. We have forecasted the total number of infection cases in two extreme situations of nationwide no lockdown and strict lockdown scenario. We expect that in future for any change in the key parameters, due to the regional differences, predictions will lie within the bounds of the above mentioned extreme plots. We computed the approximate peak infection in forwarding time and relative timespan when disease outspread halts. The most crucial parameter, the time-dependent generalization of the basic reproduction number, has been estimated. The impact of the social distancing and restricted movement measures that are crucial to contain the pandemic spread has been extensively studied by considering no lockdown scenario. Our model suggests that attaining a reduction in the contact rate between susceptible and infected individuals by practicing strict social distancing is one of the most effective control measures to manage COVID-19 spread in India. The cases can further decrease if social distancing is followed in conjunction with restricted movement.

Network synchronization, stability and rhythmic processes in a diffusive mean-field coupled SEIR model.

Connectivity and rates of movement have profound effect on the persistence and extinction of infectious diseases. The emerging disease spread rapidly, due to the movement of infectious persons to some other regions, which has been witnessed in case of novel coronavirus disease 2019 (COVID-19). So, the networks and the epidemiology of directly transmitted infectious diseases are fundamentally linked. Motivated by the recent empirical evidence on the dispersal of infected individuals among the patches, we present the epidemic model SEIR (Susceptible-Exposed-Infected-Recovered) in which the population is divided into patches which form a network and the patches are connected through mean-field diffusive coupling. The corresponding unstable epidemiology classes will be synchronized and achieve stable state when the patches are coupled. Apart from synchronization and stability, the coupled model enables a range of rhythmic processes such as birhythmicity and rhythmogenesis which have not been investigated in epidemiology. The stability of Disease Free Equilibrium (or Endemic Equilibrium) is attained through cessation of oscillation mechanism namely Oscillation Death (OD) and Amplitude Death (AD). Corresponding to identical and non-identical epidemiology classes of patches, the different steady states are obtained and its transition is taking place through Hopf and transcritical bifurcation.

Catalytic Activity of trans-Bis(pyridine)gold Complexes.

Gold catalysis has become one of the fastest growing fields in chemistry, providing new organic transformations and offering excellent chemoselectivities under mild reaction conditions. Methodological developments have been driven by wide applicability in the synthesis of complex structures, whereas the mechanistic understanding of Au(III)-mediated processes remains scanty and have become the Achilles' heel of methodology development. Herein, the systematic investigation of the reactivity of bis(pyridine)-ligated Au(III) complexes is presented, based on NMR spectroscopic, X-ray crystallographic, and DFT data. The electron density of pyridines modulates the catalytic activity of Au(III) complexes in propargyl ester cyclopropanation of styrene. To avoid strain induced by a ligand with a nonoptimal nitrogen-nitrogen distance, bidentate bis(pyridine)-Au(III) complexes convert into dimers. For the first time, bis(pyridine)Au(I) complexes are shown to be catalytically active, with their reactivity being modulated by strain.

Evaluation of platelet distribution width as novel biomarker in gall bladder cancer.

INTRODUCTION: Gall bladder cancer (GBC) tends to present in advanced stages, therefore, early diagnosis of GBC is necessary. There is no ideal single tumor marker available presently for the diagnosis and prognosis of GBC. Platelet distribution width (PDW) is an early marker for activated platelets and has been used in a variety of tumors to assess prognosis. This study was designed to evaluate the utility of PDW in identifying GBC patients and its association with tumor markers, staging and resectability of GBC. MATERIALS AND METHODS: This cross sectional study was done on 100 patients of GBC and 100 age- and sex- matched healthy controls. PDW was evaluated and compared between GBC and healthy controls. Receiver-operating characteristics was plotted to determine optimal cut-off for identifying GBC patients and to determine sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of PDW. Correlation between serum tumor markers (carbohydrate antigen 19-9, carcinoembryonic antigen, and carbohydrate antigen 125) and PDW were evaluated. Association of PDW with hyperbilirubinemia, staging and resectability of GBC was also studied. RESULTS: A significantly higher PDW with a median of 18.1 was observed in GBC as compared to healthy controls with median value of 13. PDW was found to have a very high sensitivity (90%), specificity (95%), PPV (94%) and NPV (90%) in identifying GBC at cut-off of 16 with area under the curve (AUC) of 0.97. An increase of PDW was observed with increasing stage and unresectable GBC. However, it was not statistically significant. Significant positive correlation was observed between PDW and all three serum tumor markers and good positive correlation with r = 0.61 was observed with CA 19-9. CONCLUSION: PDW was associated with GBC and may be considered as a cost- effective marker in adjunct to other investigations for the diagnosis of GBC.

Golden Age of Fluorenylidene Phosphaalkenes-Synthesis, Structures, and Optical Properties of Heteroaromatic Derivatives and Their Gold Complexes.

The substitution of 2,7-dibromo-9-fluorenyl phosphaalkenes with heteroaromatic substituents (bithiophene, benzothiophene, pyridine) offers access to interesting push-pull dye molecules. Steric shielding due to the bulky P-substituent gives marked different reactivities at the 2- and 7-positions, allowing the synthesis of mixed/asymmetric derivatives. Further functionalization via gold(I) coordination was demonstrated and increased the acceptor character, concomitant with a red-shifted absorption.

Oxygenated Cyclohexene Derivatives and Other Constituents from the Roots of Monanthotaxis trichocarpa.

Three new oxygenated cyclohexene derivatives, trichocarpeols A (1), B (2), and C (3), along with nine known secondary metabolites, were isolated from the methanolic root extract of Monanthotaxis trichocarpa. They were identified by NMR spectroscopic and mass spectrometric analyses, and the structure of trichocarpeol A (1) was confirmed by single-crystal X-ray diffraction. Out of the 12 isolated natural products, uvaretin (4) showed activity against the Gram-positive bacterium Bacillus subtilis with a MIC value of 18 µM. None of the isolated metabolites was active against the Gram-negative Escherichia coli at a ∼5 mM (2000 µg/mL) concentration. Whereas 4 showed cytotoxicity at EC50 10.2 µM against the MCF-7 human breast cancer cell line, the other compounds were inactive or not tested.

Short term biological variation of common hematological parameters in healthy subjects in a South Asian population.

There is no rigorous publication on the biological variation of common hematological parameters in South Asians to date. Also, there are few publications worldwide dealing with a variation of Reticulocyte parameters. Therefore, an attempt was made to estimate the short term within-subject and between-subject biological variation of common hematological and reticulocyte parameters. Twenty-eight healthy individuals (fifteen males and thirteen females) were selected after clinical and laboratory examination. Blood was collected in K3-EDTA vials in the morning for six consecutive days and analysed in triplicate on the Sysmex XN-1000 analyzer. Outliers were excluded and the within-subject, between-subject and analytical coefficient of variation calculated after statistical analysis by nested repeated measures ANOVA. The Reference change values (RCV), and estimates for desirable imprecision, bias, total error and index of individuality calculated. The within-subject biological variation for the studied subset belonging to South Asia closely followed published European and American studies and were similar for males and females. The between-subject variation showed differences from the published studies for white blood cells, platelets, red blood cells, hemoglobin, platelet indices and reticulocyte hemoglobin as well as between males and females for hemoglobin, red blood cell count and hematocrit. All the indices of individuality were low. This study supports the contention that the conclusions from within-subject biological variation for common hematological parameters are important and transportable to a South Asian population for short-term serial measurements. For quality specifications dependent on between-subject variation, the lower estimates from European and American studies should be used.

Short-term biological variation of differential count in healthy subjects in a South Asian population.

Estimates of Within-Subject and between subject biological variation for the white blood cell differential count (DC) have not been reported in South Asia. Therefore, we attempted to measure the short-term biological variation estimates for DC. The study was conducted on 28 healthy volunteers (15 males and 13 females). Blood from the volunteers was collected in the morning in K3-EDTA vials and analyzed in triplicate on the Sysmex XN-1000 analyzer, for six consecutive days. The Within subject, between subject and analytical coefficient of variation of the DC was calculated from the results by nested repeated measures ANOVA after outlier exclusion. The Reference change values (RCV) were also calculated. The within-subject variation for eosinophil Count and between subject variation for basophils in our study from South Asia was greater than the published European and American studies. Males and females showed similar biological variation for DC. The within-subject variation of other parameters (Neutrophils, Lymphocytes, Monocytes and Basophils) were similar or showed only mild differences to the published studies. The markedly different within-subject variation for Eosinophil counts suggest that the RCV for DC in South Asians need to be different from the published data in order to have clinical relevance. The Within-subject variation values of the other parameters seem transportable from the published European and American studies, but the small differences found mean that further regional estimates need to be reported for robust evidence of the same.

The Self-Assembly of [{Ag3(C≡CtBu)2}n]n+ Building Units into a Template-Free Cuboctahedron and Anion-Encapsulating Silver Cages.

We describe the controlled synthesis of silver acetylide clusters based on a simple polymeric [Ag3L2]+ (L = -C≡CtBu) building block. A linear one-dimensional polymeric structure shows alternating pyramidal motifs and is the basic repeating unit forming discrete molecular cages (pentamers [X⊂Ag15L10]4+ and hexamers [PF6⊂Ag18L12]5+) obtained by incorporating suitable templates. These motifs and a rare template-free cuboctahedral [Ag12L8]4+ cluster (tetramer) were crystallographically characterized.

Halogen Bonding Helicates Encompassing Iodonium Cations.

The first halonium-ion-based helices were designed and synthesized using oligo-aryl/pyridylene-ethynylene backbones that fold around reactive iodonium ions. Halogen bonding interactions stabilize the iodonium ions within the helices. Remarkably, the distance between two iodonium ions within a helix is shorter than the sum of their van der Waals radii. The helical conformations were characterized by X-ray crystallography in the solid state, by NMR spectroscopy in solution and corroborated by DFT calculations. The helical complexes possess potential synthetic utility, as demonstrated by their ability to induce iodocyclization of 4-penten-1-ol.

Alkynyl Coinage Metal Clusters and Complexes-Syntheses, Structures, and Strategies.

In this Concept we discuss how the chemistry of coinage metal complexes based on alkynyl ligands has developed over the past decades. The rich coordination of alkynyl, that exhibit both η1 (end-on) and η2 (side on) modes, includes non-bridged systems, as well as bridging of up to four (or six) metal centres. Resulting metal clusters often exhibit highly regular structures and typical coordination motifs forming fascinating assemblies exploiting this versatile coordination. Metallophilic interactions are often an important driving force for the formation of large clusters. In addition, the use of co-ligands as well the possibility to encapsulate counter ions greatly increases the chemical and structural diversity. Herein we attempt to summarize and highlight design principles towards multinuclear homo and hetero-bi-metallic coinage metal clusters of alkynyl ligands.

Rich Coordination Chemistry of π-Acceptor Dibenzoarsole Ligands.

A series of dibenzoarsole (also known as 9-arsafluorene) derivatives have been prepared, and their coordination chemistry has been investigated. The different ligand topology and the arsenic substituents govern the reactivity of the ligands. We report various crystal structures of palladium and platinum complexes derived from this family of ligands. The biphenyl backbone of the bridged bidentate ligands allows very flexible coordination. We have also studied the application of an allylic Pd complex in nucleophilic substitution reactions, revealing that the benzoarsole substituent is susceptible to metal insertion.