Well-Defined Mn(II)-complex Catalyzed Switchable De(hydrogenative) Csp3 -H Functionalization of Methyl Heteroarenes: A Sustainable Approach for Diversification of Heterocyclic Motifs.

Catalytic activities of Mn(I) complexes derived from expensive MnBr(CO)5 salt have been explored in various dehydrogenative transformations. However, the reactivity and selectivity of inexpensive high spin Mn(II) complexes are uncommon. Herein, we have synthesized four new Mn(II) complexes and explored switchable alkenylation and alkylation of methyl heteroarenes employing a single Mn(II)catalyst. The developed protocol selectively furnishes a series of functionalized E-heteroarenes and C-alkylated heteroarenes with good to excellent yields. Various medicinally and synthetically useful compounds are successfully synthesized using our developed protocol. Various controls and kinetics experiments were executed to shed light on the mechaism,which reveals that α-C-H bond breaking of alcohol is the slowest step.

Well-Defined NNS-Mn Complex Catalyzed Selective Synthesis of C-3 Alkylated Indoles and Bisindolylmethanes Using Alcohols.

Herein, we demonstrated Mn-catalyzed selective C-3 functionalization of indoles with alcohols. The developed catalyst can also furnish bis(indolyl)methanes from the same set of substrates under slightly modified reaction conditions. Mechanistic studies reveal that the C-3 functionalization of indoles is going via a borrowing hydrogen pathway. To highlight the practical utility, a diverse range of substrates including nine structurally important drug molecules are synthesized. Furthermore, we also introduced a one-pot cascade strategy for synthesizing C-3 functionalized indoles directly from 2-aminophenyl ethanol and alcohol.

Supramolecular Interaction of Molecular Cage and ß-Galactosidase: Application in Enzymatic Inhibition, Drug Delivery and Antimicrobial Activity.

Enzyme inhibitors play a crucial role in diagnosis of a wide spectrum of diseases related to bacterial infections. We report here the effect of a water-soluble self-assembled PdII8 molecular cage towards ß-galactosidase enzyme activity. The molecular cage is composed of a tetrapyridyl donor (L) and cis-[(en)Pd(NO3 )2 ] (en=ethane-1,2-diamine) acceptor and it has a hydrophobic internal cavity. We have observed that the acceptor moiety mainly possesses the ability to inactivate the ß-galactosidase enzyme activity. Kinetic investigation revealed the mixed mode of inhibition. This inhibition strategy was extended to control the growth of methicillin-resistant Staphylococcus aureus. The internalization of the Pd(II) cage inside the bacteria was confirmed when bacterial solutions were incubated with curcumin loaded cage. The intrinsic green fluorescence of curcumin made the bacteria glow when put under an optical microscope. Furthermore, this curcumin loaded molecular cage shows an enhanced antibacterial activity. Thus, PdII8 molecular cage is quite attractive due to its dual role as enzyme inhibitor and drug carrier.

Selective Synthesis of 2-Substituted and 1,2-Disubstituted Benzimidazoles Directly from Aromatic Diamines and Alcohols Catalyzed by Molecularly Defined Nonphosphine Manganese(I) Complex.

Herein, we present a selective synthesis of 2-substituted and 1,2-disubstituted benzimidazoles by acceptorless dehydrogenative coupling of aromatic diamine with primary alcohols. The reaction is catalyzed by a phosphine-free tridentate NNS ligand-derived manganese(I) complex.

Static second hyperpolarizability of inverse sandwich compounds (M1-C5H5-M2) of alkali (M1 = Li, Na, K) and alkaline earth metals (M2 = Be, Mg, Ca).

In the investigated inverse sandwich complexes, charge transfer from alkali metal (M1) led to aromatically stabilized Cp ring, which prevented further charge transfer from the alkaline earth metal (M2). This electron push effect resulted in diffusion of electron density from the outermost "ns" subshell of alkaline earth metal. The alkaline earth metal is weakly bound to the alkali metal-C5H5 complex. The vertical ionization energy of the chosen M1-Cp-M2 complexes was smaller than that of the corresponding alkaline earth metals. Large second hyperpolarizability (106-108 a.u.) was obtained for the studied molecules. The correction due to the basis set superposition error (BSSE) in the calculated second hyperpolarizability was found to be small for larger systems, while it was rather significant for small systems. The MP4SDQ and CCSD results were in fair agreement, which indicates the necessity of higher order electron correlation treatment in the accurate description of second hyperpolarizability. Calculated dynamic second hyperpolarizabilities at 1064 nm were found to increase considerably for most of the chosen metal complexes.

Successive lithiation of acetylene, ethylene and benzene: a comprehensive computational study of large static second hyperpolarizability.

This work is a revisit of the study of the electron correlation effect of lithium substitution on the second hyperpolarizability (106 a.u.) of acetylene, ethylene and benzene. The large quenching of mean second hyperpolarizability has been addressed by CCSD calculations. The inclusion of triple excitation in the MP4 method generally overestimates second hyperpolarizability in comparison to the MP4SDQ method. The present CCSD γav value of C6Li6: 405 × 104 a.u. obtained with a relatively larger basis set established the earlier prediction of Sadlej et al. [Phys. Chem. Phys. Chem., 2000, 2, 3393-3399] where degenerate non-dipolar transitions in low lying excited states play the crucial role. The successive lithiation results in gradual red shifting of transition energy leading to significant enhancement of second hyperpolarizability. Most of the chosen DFT functionals predict the correct qualitative trend of second hyperpolarizability. The quantitatively different results may be attributed to the case when the ground state wave function cannot be approximated by a single SD.

A facile approach for selective detection of arsenite ions using plasmonic behaviour of silver nanoparticles.

A specific reagent/aptamer-free easy redox strategy between silver(I) moieties present in a citrate-stabilized colloidal silver nanoparticle (NP) system and arsenite ions is described that enables plasmonic change of AgNPs for the selective quantification of arsenite ions in the range of 0 to 30 µM with a low limit of quantification value of 50 nM (5.3 ppb).

Designing Cobalt(II) Complexes for Tandem Dehydrogenative Synthesis of Quinoline and Quinazoline Derivatives.

In this work, we have constructed three new Co(II) complexes in which steric features govern their structural geometry. The metal ligand-cooperation behavior of the alkoxy arm is utilized to explore the catalytic activities of these complexes with respect to dehydrogenation. A wide range of C-3-substituted quinoline and quinazoline derivatives were synthesized in high yields. The developed protocol's usefulness is enhanced by the chemoselective transformation of different fatty alcohols to synthesize heterocycles having distal unsaturation. Various kinetic, mechanistic, and control studies were conducted to comprehend the reaction route.

Thiol ligand-mediated exfoliation of bulk sulfur to nanosheets and nanodots: applications in antibacterial activity.

Reducing bulk materials to layers or dots results in profound alterations in their physiochemical and optoelectronic properties, leading to a wide array of applications, spanning from device manufacturing to biomedicine. In this regard, the preparation of sulfur nanomaterials has garnered significant attention due to their low toxicity. Traditional methods for sulfur nanomaterial synthesis often involve harsh reaction conditions, leaving a gap for convenient approaches to create nanomaterials, such as nanosheets (NSs) and nanodots (NDs). Herein, the mechanical exfoliation of bulk sulfur using a surfactant thiol ligand with probe sonication is reported, making a unique contribution to existing methods. In the reported method, the thiol group binds to sulfur surfaces, facilitating exfoliation and stabilization, while the hydrophilic ends provide functional groups for exfoliated nanomaterials. Exfoliation can yield either nanosheets or nanodots, depending on the thiol ligand and exfoliation time. This approach offers the opportunity to exfoliate bulk sulfur using bioactive thiol ligands. With this goal in mind, bulk sulfur was exfoliated with 4-mercaptophenylboronic acid (BA) to target Gram-positive bacteria. This innovative exfoliation strategy of bulk sulfur using thiol ligands holds immense promise for synthesizing functionalized sulfur nanomaterials with wide-ranging applications, particularly in biomedicine.

Experimental and theoretical insights for designing Zn2+ complexes to trigger chemo-selective hetero-coupling of alcohols.

Designing well-defined Zn-complexes for sustainable dehydrogenative catalysis overcoming the difficulties associated with activating Zn2+(d10)-metal species is considered paramount goal in catalysis. Herein, we explore the plausibility of ß-alkylation of secondary alcohols with primary alcohols by well-defined 3d10 Zn-complexes. Detailed organometallic and catalytic investigations, in conjunction with computational analyses, were conducted to ascertain the potential involvement of the catalyst at various stages of the catalytic process.

Reversing the Trend: Deciphering Self-Assembly of Unconventional Amphiphiles Having Both Alkyl-Chain and PEG.

In the field of molecular self-assembly, the core of an assembly is always made up of hydrophobic moiety like a long alkyl chain, whereas the outer part has always been a hydrophilic moiety such as poly(ethylene glycol) (PEG), or charged species. Hence, reversing the trend to manifest self-assembled structures with a PEG core and a surface consisting of alkyl chains in aqueous system is incredibly challenging. Herein, we architected a unique class of cationic bolaamphiphiles containing low molecular weight PEG and alkyl chains of different lengths. The bolaamphiphiles spontaneously form vesicles without external stimuli. These vesicles are unprecedented because PEG makes up the vesicle core, while the alkyl chains appear on the vesicles' exterior. Hence, this particular design reverses the usual trend of self-assembly formation. The vesicle size increases with the increase in alkyl chain-length. To our great surprise, we obtained large micelles for longest alkyl-chain amphiphile, which in turn act as a gemini amphiphile. The shift from a particular bolaamphiphile to gemini amphiphile with the variation of alkyl chain is also unexplored. Therefore, this specific class of self-assembled structure would compound a new paradigm in molecular self-assembly and supramolecular chemistry.

Manganese Complex Catalyzed Sequential Multi-component Reaction: Enroute to a Quinoline-Derived Azafluorenes.

The development of innovative synthetic strategies for constructing complex molecular structures is the heart of organic chemistry. This significance of novel reactions or reaction sequences would further enhance if they permitted the synthesis of new classes of structural motifs, which have not been previously created. The research on the synthesis of heterocyclic compounds is one of the most active topics in organic chemistry due to the widespread application of N-heterocycles in life and material science. The development of a new catalytic process that employs first-row transition metals to produce a range of heterocycles from renewable raw materials is considered highly sustainable approach. This would be more advantageous if done in an eco-friendly and atom-efficient manner. Herein we introduce, the synthesis of various new quinoline based azafluorenes via sequential dehydrogenative multicomponent reaction (MCR) followed by C(sp3)-H hydroxylation and annulation. Our newly developed, Mn-complexes have the ability to direct the reaction in order to achieve a high amount of desired functionalized heterocycles while minimizing the possibility of multiple side reactions. We also performed a series of control experiments, hydride trapping experiments, reaction kinetics, catalytic intermediate and DFT studies to comprehend the detailed reaction route and the catalyst's function in the MCR sequence.

Solid pseudopapillary neoplasm of the pancreas mimicking gastrointestinal stromal tumour.

Solid pseudopapillary neoplasm (SPN) of pancreas is an uncommon low-grade malignant tumour that has a remarkable postoperative cure rate. Improved awareness and widespread use of imaging have resulted in more frequent diagnosis of these tumours. We report a case of a woman in her 20s who had an abdominal lump identified as a gastrointestinal stromal tumour on imaging elsewhere. The patient was reevaluated in our hospital and given a provisional diagnosis of SPN on radiology, which was later confirmed on postoperative histopathology.

Post-functionalization of sulfur quantum dots and their aggregation-dependent antibacterial activity.

Sulfur quantum dots (SQDs) have emerged as an intriguing class of luminescent nanomaterial due to their exceptional physiochemical and optoelectronic properties. However, their biomedical application is still in its infancy due to the limited scope of their surface functionalization. Herein, we explored the surface functionalization of SQDs through different thiol ligands with tuneable functionality and tested their antibacterial efficacy. Notably, very high antibacterial activity of functionalized SQDs (10-25 ng ml-1) was noted, which is 105 times higher compared to that of nonfunctionalized SQDs. Moreover, a rare phenomenon of the reverse trend of antibacterial activity through surface modification was observed, with increasing surface hydrophobicity of various nanomaterials as the antibacterial activity increased. However, we also noted that as the surface hydrophobicity increased, the SQDs tended to exhibit a propensity for aggregation, which consequently decreased their antibacterial efficacy. This identical pattern was also evident in in vivo assessments. Overall, this study illuminates the importance of surface modifications of SQDs and the role of surface hydrophobicity in the development of antibacterial agents.

Multiple keratotic papules on palm.

Porokeratotic eccrine ostial and dermal duct nevus (PEODDN) is a rare nonhereditary malformation of the eccrine duct. A relationship with linear porokeratosis is not yet established; some consider it as a rare variant of porokeratosis involving the acrosyringium, whereas others consider it a separate entity based on distinctive clinical features and histologic accentuation within ostial structures. A 7-year-old girl presented with multiple asymptomatic keratotic papules over her right palm, present since the age of 6 months. These papules were arranged in a linear distribution over the palm and middle finger of the right hand. Most of the papules were discrete. However, lesions on the middle finger coalesced to form a plaque. Histology revealed a keratin filled deep invagination of the epidermis, notable for a column of parakeratosis ("cornoid lamella"). The dermis was notable for dilated eccrine ducts and absent inflammation. Considering the clinical and histological evidence, a diagnosis of PEODDN was made. Its clinical resemblance to linear lichen planus and linear porokeratosis is discussed. Also, we provide a brief review of this rare condition.

Zinc and skin: a brief summary.

Zinc is an essential trace element that is an integral component of many metallo-enzymes in the body and thus serves many biological functions. The clinical presentation of zinc deficiency varies and depends on serum zinc level. Whereas a significantly low serum zinc level results in clinical features similar to acrodermatitis enteropathica, mild hypozincemia presents with a less characteristic appearance; hence it may be underdiagnosed. Recognition of various cutaneous lesions is required for suspecting and identifying cases of zinc deficiency. Although many laboratory tests are useful, therapeutic response in suspected cases remains the gold standard of diagnosis. Serum zinc estimation alone is not very reliable because disease activity may not necessarily correlate with serum zinc level. Zinc supplementation results in a rapid response and the skin lesions heal without permanent sequelae. However, pigmentary alterations may persist longer. Predisposing factors should be identified and corrected. This brief review summarizes the identification and management of clinical zinc deficiency.

Evaluation of the antimicrobial potential of two flavonoids isolated from limnophila plants.

The antimicrobial potential of two bioflavonoids, i.e., 5,7-dihydroxy-4',6,8-trimethoxyflavone (1) and 5,6-dihydroxy-4',7,8-trimethoxyflavone (2), isolated from Limnophila heterophylla Benth. and L. indica (Linn.) Druce (Scrophulariaceae), respectively, were evaluated against the microbial strains Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, Alternaria solani, and Candida albicans. Compounds 1 and 2 exhibited moderate but broad antimicrobial activities against both Gram-positive and Gram-negative bacteria and also against the fungal pathogens. Moreover, the mechanism of action of 1 and 2 on the cellular functions or structures of some of the microorganisms was studied. Compound 1 showed a bactericidal effect against E. coli and S. aureus (MICs of 200 and 250 µg/ml, resp.), while compound 2 was found to effectively kill B. subtilis by cell lysis. The growth of A. solani and C. albicans was inhibited by compounds 1 and 2, respectively. The effects of the flavonoids on the cellular structures and the carbohydrate metabolic pathways were studied by scanning electron microscopy (SEM) of the treated cells and by assessing the specific activity of key enzymes of the pathways, respectively. At sublethal doses, they enhanced the activity of gluconeogenic fructose bisphosphatase, but decreased the activity of phosphofructokinase and isocitrate dehydrogenase, the key enzymes of the EmbdenMeyerhofParnas pathway and the tricarboxylic acid cycle, respectively.

Manganese catalyzed switchable C-alkylation/alkenylation of fluorenes and indene with alcohols.

The usage of earth-abundant, nontoxic transition metals in place of rare noble metals is a central goal in catalysis. This would be especially interesting when the reactivity and selectivity patterns can be tuned. Herein, we introduced the first Mn-catalyzed selective C-alkylation and olefination of fluorene, and indene with alcohols. Various substrates including benzylic, heteroaromatic, and aliphatic primary and secondary alcohols are employed as alkylating agents. Mechanistic investigations and a kinetic study underpin the involvement of the olefinated intermediate to furnish the alkylated product.

Microwave sintering of refractory metals/alloys: W, Mo, Re, W-Cu, W-Ni-Cu and W-Ni-Fe alloys.

Refractory metals and alloys are well known for their high mechanical properties which make them useful for wide range of high temperature applications. However, owing to the refractoriness of these metals and alloys, it is very difficult to consolidate them under moderate conditions. Conventional P/M processing is a viable sintering technique for these refractory metals. One of the constraints in conventional sintering is long residence time which results in undesirable microstructural coarsening. This problem gets further aggravated when using smaller (submicron and nano) precursor powder sizes. Furthermore, conventional heating is mostly radiative, which leads to non-uniform heating in large components. This review article describes recent research findings about how these refractory metals and alloys (W, Mo, Re, W-Cu, W-NiCu and W-Ni-Fe) have been successfully consolidated using microwave sintering. A comparative study with conventional data has been made. In most cases, microwave sintering resulted in an overall reduction of sintering time of up to 80%. This sintering time reduction prevents grain growth substantially providing finer microstructure and as a result better mechanical properties have been observed.

Dyshidrosiform Pemphigus vulgaris: Report of an unusual case.

Dyshidrosiform Bullous pemphigoid is a well-known entity, but dyshidrosiform pemphigus vulgaris has rarely been described. Our patient, a 36-year-old female, with a known case of pemphigus vulgaris (PV) for the last 6 years, presented with a 3 month history of a dyshidrosiform eruption of the soles. On the basis of histopathological and direct immunofluorence (DIF) findings, the new eruption was diagnosed as PV. We report our case as dyshidrosiform pemphigus vulgaris.