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On April 28 2021, an earthquake of MW 6.4 occurred near Sonitpur, Assam, India. The epicenter was 43 km away from Tezpur, Assam with a focal depth of 34 km. The National Center for Seismology (NCS), Delhi reported the maximum intensity of MMI-V whereas the United States Geological Survey (USGS) reported the maximum intensity of MMI-VII. Preliminary reports suggest a reverse slip component for the earthquake, which occurred close to the previously reported Kopili fault. This fault is the cause of two damaging earthquakes in the past i.e., 1869 Cachar earthquake and the 1943 earthquake. The April 28 2021, Sonitpur earthquake caused widespread liquefaction, building damage, and lateral spreading as far as 90 km from the epicenter. The present study reports preliminary damages and ground effects observed soon after the earthquake along with a comparative analysis with previously reported damages around the area during the historical earthquakes. The farthest reported liquefaction occurred during the earthquake was plotted with other case studies which were well in agreement with the previous literature. The possible reason for the extensive liquefaction and ground cracks is inferred to be due to site amplification within a sedimentary basin. Therefore, the occurrence of the 2021Sonitpur, Assam earthquake emphasizes the seismic hazard scenario for the Brahmaputra Basin and Bengal Basin, which further requires more detailed study in terms of paleoseismology, liquefaction hazard zonation and seismic hazard assessment. In addition, the damages to the buildings highlight the implementation of proper building codes considering the liquefaction hazard zonation map for the study area. [ABSTRACT FROM AUTHOR]

Sikkim, a north‐eastern state of India, has a very specific and unique place in the tourism map of India. Every year, lakhs of people visit the state. To accommodate such floating population in the area, some big towered home stays/hotels have been constructed. However, the area is under the threat of many natural disasters such as earthquake, landslide, land subsidence, cloudburst, etc. In the year 2021, within a span of 8 months (April–November), the Sikkim state hosted four light to moderate earthquakes (Mw 4.1–Mw 5.1). Out of these, the strongest earthquake (Mw 5.1) occurred on 5 April 2021, which was well experienced in the parts of Indian states (i.e., Sikkim, West Bengal, Bihar) and across International borders, viz Bangladesh, Nepal, Bhutan, and China. Fortunately, this earthquake did not cause any major damage in the region. However, in the last two decades, one moderate (Mw 5.3) and one strong earthquake (Mw 6.9) has occurred in the Sikkim region on 14 Feb 2006 and 18 September 2011, respectively. Both of these earthquakes caused well enough damage to the residential as well as commercial buildings. Apart from infrastructural degeneracy, the 2011 Sikkim Earthquake (Mw 6.9) also caused generation of co‐seismic landslides within ~100 km epicentral distance from the earthquake. After a decade, from the 2011 earthquake, Gangtok city and other parts of the state have been rebuilt and reconstructed again, but most of the newly constructed and old refurbished buildings are established in the steep slope areas without considering the geotechnical properties of the underlying soil. These structures could be vulnerable during moderate to strong earthquakes. Therefore, the present study unfurled a question "Did we learn any lesson from the 2011 Sikkim Earthquake?". Furthermore, the study calls for earthquake hazard adaptation measures in the tectonically sensitive Himalayan region in order to safeguard the lives and vital infrastructure. [ABSTRACT FROM AUTHOR]

A straightforward catalyst-free synthetic approach has been developed for the synthesis of a quinoxaline derivative, 4-phenyl-4-(pyridin-2-yl)-4,5-dihydropyrrolo[1,2-a]quinoxaline (L), by the reaction of 2-benzoyl pyridine and pyrrole-1-anillin in ethanol. L in the presence of a stoichiometric amount of copper(II) perchlorate becomes decomposed unprecedentedly to produce a copper(II) complex, [CuL′2(H2O)2](ClO4)2 (1) (L′ = 2-benzoylpyridine), in aqueous methanolic medium. X-ray structures show that both L and 1 crystallize in the monoclinic crystal system with the P21/n space group. The structure of 1 is a copper centred centrosymmetric axially elongated octahedron with two (N,O) chelating ligands L′ occupying the equatorial positions (Cu–O of 2.013(2) Å and Cu–N of 1.963(2) Å) and two aqua ligands occupying the axial positions (Cu–O(aqua) bonds of 2.377(3) Å). Detailed computational analysis encompassed a combination of density functional theory (DFT) calculations and molecular dynamics (MD) simulations. The structural features of the compounds, local reactivity properties, stability, and spin density surfaces including frontier orbital energies were studied with DFT calculations in detail. [ABSTRACT FROM AUTHOR]

Every year, during the monsoon period (June–September), series of land subsidence incidences are reported from the Southern Western Ghats in India. These land subsidences occur primarily due to subsurface erosion, which leads to formation of soil pipes. These soil pipes are geo-morphologically an outcome of land degradation process that significantly influences the hill slope hydrology which makes the slopes vulnerable, and affects the human lives as well. However, detection of these subsurface pipes remains a serious challenge. Most of the previous studies are based on surface investigations, without considering the subsurface features. The present study aims to provide a more detailed account of these less-studied geomorphic features (soil pipes) using an integrated approach. The main purposes of the present study are to 1) describe the characteristic of the soil pipes and 2) to quantify the scale of piping activity; based on both surface and subsurface investigations in watershed scale. The remote sensing and GIS platform were used to delineate watershed boundary, identify geo morphological setup of the terrain, detailed landuse information and to bring out change in landuse, landcover pattern. The geomorphic mapping was carried out to identify the type of pipes, location of its inlet, outlet and other subsequent deformation features. The resistivity survey was done to map geometry of the pipe, piping network, subsurface lithology, and get the water table depth. The resistivity survey results indicate that the density of pipes are more than the estimated through surface mapping. Similarly, the length of the pipes is more than the mapped pipe through the surface mapping. The combined results suggest that the region is rich in these kinds of pipe features and may create hazard to the society residing in those areas. This study further underlined the importance of detailed study about soil piping phenomena to minimize its threat to human habitation and to provide specific recommendations to prevent the recurrence. [ABSTRACT FROM AUTHOR]

Landslide is one of the devastating natural phenomenon that threatens human life and property. Every year a number of persons lost their lives due to the landslides. Therefore, a better understanding and characterization of landslide is very essential for adopting mitigation strategies to contain the adversities of this natural hazard. Information on landslides from different climatic setup are very essential for better understanding of the influence of weathering, rainfall, or topography on landslide generation. Weathering is one of the important causative factor for landslide generation in the moderate topography or inactive mountainous terrain. The Western Ghats including the Deccan Traps, an inactive mountain range, receives torrential rainfall. Intense rainfall in these areas enhances the weathering processes and fabricates thick soil covers. Mahabaleshwar area, Maharashtra was chosen as a case study, where high elevated part is covered by lateritic layer and each lava flow unit is separated by a thin weathered bed of red bole. The area experiences series of landslides during the summer monsoon months. Mainly two types of landslides have been identified in the area confined with the red bole bed and powdery lateritic soil. The first type of landslides occur at higher elevations (≥1200m) where horizontal beds of permeable laterites underlined by impermeable thick basalt beds. The rain water infiltrates down and spread laterally within the permeable lateritic beds. It finally spouts at lower plateau elevations and triggers mainly debris flows. The other category of landslides occurs where the weathered red bole bed separates two successive lava flows. The percolating water from the secondary porosities (joints and inter connected vugs) comes out from the contact zones of basalt and red bole bed in the form of seepages. It erodes the red bole bed and as a result the overlying masses hang and consequently lead to rock fall. The Chemical Index of Alteration (CIA) of the representative samples from landslide locations indicates significant weathering. The CIA values for the fine lateritic soil are up to 98% whereas for the red bole bed it varies from 77 to 85%. This suggests a high chemical weathering and higher erodibility. The association of active landslide locations with the red bole bed and fine lateritic soil suggests a close relation between weathering and landslide occurrences in the area. [ABSTRACT FROM AUTHOR]

A metal-free highly diastereoselctive [3 + 2] cycloaddition reaction has been developed between N-phenacylbenzothiazolium bromides and prochiral cyclopentene-1,3-diones. The active 1,3 dipole benzothiazolium N-phenacylide was generated in situ with the treatment of DIPEA, and the corresponding cycloaddition products were obtained in excellent yields under mild reaction conditions. The scope of the reaction is quite broad, tolerating a variety of aryl and heteroaromatic groups. A catalytic asymmetric approach was also studied preliminarily, and moderate enantioselectivity was achieved. [ABSTRACT FROM AUTHOR]

The purpose of study was to conjugate and evaluate methotrexate with C 60 -fullerenes and multi-walled carbon nanotubes (MWCNTs) for better drug delivery to cancer cells, and also to compare these two systems. C 60 -fullerenes and MWCNTs were functionalized by 1,3-dipolar cycloaddition using glycine and paraformaldehyde. Methotrexate (MTX) was esterified and conjugated to the functionalized carbon-based carriers. The conjugates were characterized for micromeritics and drug conjugation. The systems were evaluated for drug release in various pH, MTT cytotoxicity assay, protein binding, cellular uptake, haemolytic profile and pharmacokinetics. Spectroscopic studies confirmed the successful conjugation of drug to the aminated carbon-based carriers. The developed systems released more drug at the pH of cancer cells to that of the pH of plasma. The carriers were compatible with erythrocytes and offered substantial cytotoxicity. Better cellular uptake was confirmed by confocal laser scanning microscopy. C 60 -fullerenes/MWCNTs modulated the pharmacokinetic profile of drug in desired manner, resulting in better retention and compartment availability. However, the results from C 60 -fullerenes were observed to be better than that from MWCNTs. The present findings established the potential of carbon-based aminated nanocarriers for delivery of methotrexate in safer and effective manner. [ABSTRACT FROM AUTHOR]

Abstract: Carbon loaded polyethylene films were selected as the base substrate for a mechanically flexible and conductive sensing material for use wound monitoring technologies. The films were processed using laser ablation of the surface to increase the effective surface area of the electrode and then subject to an oxidative electrochemical etch to improve the electron transfer kinetics. The surface morphology of the resulting films was analysed and the electrode performance in relation to monitoring uric acid, a key wound biomarker, was optimized. A prototype smart bandage was designed, based on interfacing the mesh to a portable potentiostat, and the response to urate and potential interferences assessed. [Copyright &y& Elsevier]

The Palaeozoic granites forming the Dalhousie pluton occur as an elongated body intruded into the core of an antiform in Salkhala metasedimentary rocks and are referred to herein as Dalhousie granites (DG). The studied mesoscopic structures, for example, well‐developed and randomly distributed megacrysts of K‐feldspar at the core part of massif, show undeformed porphyritic nature, whereas augen along with the mylonitic foliation and parallelly aligned feldspar megacrysts are dipping towards north‐north‐east (NNE) in the marginal part. The presence of aplite veins is evidence of final stage crystallization, where these rocks rapidly crystallized from siliceous residual fluids/solutions that escaped along fractures in the granites. Moreover, the granites show intrusive as well as thrusted contact with the Chamba metamorphics. The microscopic study from the marginal parts shows the dynamic recrystallization of quartz along with the fractures filled with secondary material oriented opposite to the top‐to‐the‐SW. Whereas euhedral quartz grains with undeformed grain boundaries, compositional zoning in plagioclase, and magmatic (perthite) texture of K‐feldspar are present in the core of Dalhousie pluton. In addition, a new whole‐rock geochemical dataset of DG is presented and investigated to elucidate the petrogenesis and tectonic environment. The geochemical data shows that DG (dominantly monzogranites) are formed from a pelitic source‐derived, (molar Al2O3/CaO + Na2O + K2O > 1.1) strongly peraluminous (S‐type) calc‐alkaline magma. This magma was generated by muscovite vapour absent dehydration melting. Harker bivariate plots indicate that fractional crystallization was a dominant process during the evolution of these granites. The tectonic discrimination diagrams suggest that DG were generated in syn‐collisional setting. Exceptionally high Pb in DG occurred due to primary melt generation at low‐temperature during partial melting (low‐degree melting) of the pelitic source rock. Trace and rare earth elements characteristics, such as positive anomaly of Zr show a notable amount of zircon as one of the accumulating phases. A pronounced negative Eu anomaly (EuN/Eu* = 0.04–0.66), along with high silica content and highly varied trace element ratios in these rocks, show that these are fairly evolved granites. [ABSTRACT FROM AUTHOR]

By using double-time temperature dependent Green's function method, expressions for dielectric constant are derived. Model Hamiltonian used by earlier workers is modified and used in the derivation. Model values are fitted and compared with experimental data of others. [ABSTRACT FROM AUTHOR]

Herein we first report the unprecedented synthesis of tetrazene‐based cobalt complexes using unusual coupling of amines via dehydrogenation. These cobalt complexes were employed for dehydrogenative coupling reactions to synthesize N‐heterocycles (quinoline, and quinazolinone). Based on control experiments and IR identification of intermediates, we proposed a plausible reaction mechanism. Synthesis protocols were utilized for preparative scale synthesis and biologically active molecule (±)‐galipinine synthesis. [ABSTRACT FROM AUTHOR]

This manuscript demonstrates the synthesis, structural characterization, computational studies, and biomimics of the phenazine oxidase activity of a newly designed cobalt (III) complex, [Co (dpa)(dpa‐H+)(N3)2]Cl2 (1) [dpa = 2,2′‐dipyridylamine] under an aerobic condition. The crystal structure analysis reveals that the cobalt (III) center adopts an octahedral geometry, and the complex forms a beautiful supramolecular framework through noncovalent interactions. The cobalt (III) catalyst turns out to be a promising catalyst for the oxidative coupling of o‐phenylenediamine (OPD) in oxygen‐saturated methanol with an excellent turnover number, kcat = 7.85 × 103 h−1. Spectrophotometric, electrochemical, mass spectrometry, and computational analysis ensure that the course of catalysis undergoes through a catalyst‐substrate complexation, facilitating the development of cobalt‐iminobenzoquinone species in the solution. The computational calculations employing the density functional theory (DFT) throw a light to the mechanistic insights of the phenazine oxidase mimics. ETS‐NOCV (extended transition state‐natural orbitals for chemical valence) plots of the reactive intermediates portray the coordination‐driven depletion of electron density from the nitrogens of OPD to cobalt center leading to the enhancement of electrophilic character on para‐positioned C‐atoms with respect to N‐atoms of OPD, therby catalyzing the nucleophilic attack by second OPD to produce the oxidation product, 2,3‐diaminophenazine (DAP). Interestingly, we are able to isolate the oxidation product of the OPD oxidation reaction as a hydrated chloride salt, DAPH+Cl− ·3H2O (2). The crystal engineering perspectives of 2 attribute the intriguing fate of the secondary chlorides for the stabilization of the oxidation product in crystalline phase. [ABSTRACT FROM AUTHOR]

Twenty-five (Ia–Iu, IIa–IIb, IIIa, and IVa) diarylidene-N-methyl-4-piperidones (DANMPs) were synthesized and characterized via UV, FT-IR, NMR, and MS while Id was characterized also by single crystal XRD. Twenty-one compounds shortlisted after initial in vitro anti-plasmodial activity successive screenings at 100 μM and 10 μM were evaluated for their IC50s against chloroquine-sensitive Pf3D7, chloroquine-resistant PfINDO, and artemisinin-resistant PfMRA-1240 strains. The four most promising compounds were Ie (IC50s μM 0.35MRA, 1.39INDO, 1.923D7), If (IC50s μM 1.07MRA, 1.36INDO, 3.393D7), Ir (IC50s μM 0.74MRA, 2.45INDO, 1.443D7), and In (IC50s μM 1.27MRA, 1.8INDO, 1.73D7). Resistance indices as low as 0.2 to 0.5 for these potent compounds and <1 for most other compounds suggest their greater potency against drug resistant strains than the drug sensitive strain. The parasiticidal action of Ir was seen within 4 h against the trophozoite stage of the parasite, which is known to express the highest levels of PLP synthase. In silico docking scores of −7.0 to −8.0 kcal mol−1 between potent DANMPs and PfPLP synthase, the direct binding of Ir studied by SPR to recombinantly expressed and purified PfPdx-1 and inhibition of Pdx1 enzymatic activity by Ir suggest this vital enzyme to be a probable target for the DANMPs. The non-hemolytic nature of Ir and conformity of most DANMPs to Lipinski's parameters indicate their potential as new anti-plasmodial leads with PfPLP synthase as one of their targets. [ABSTRACT FROM AUTHOR]

Base-metal catalysts Co1, Co2 and Co3 were synthesized from designed pincer ligands L1, L2 and L3 having NNN donor atoms respectively. Co1, Co2 and Co3 were characterized by IR, UV–Vis. and ESI-MS spectroscopic studies. Single crystal X-ray diffraction studies were investigated to authenticate the molecular structures of Co1 and Co3. Catalysts Co1, Co2 and Co3 were utilized to study the dehydrogenative activation of alcohols for N-alkylation of amines, α-alkylation of ketones and synthesis of quinolines. Under optimized reaction conditions, a broad range of substrates including alcohols, anilines and ketones were exploited. A series of control experiments for N-alkylation of amines, α-alkylation of ketones and synthesis of quinolines were examined to understand the reaction pathway. ESI-MS spectral studies were investigated to characterize cobalt-alkoxide and cobalt-hydride intermediates. Reduction of styrene by evolved hydrogen gas during the reaction was investigated to authenticate the dehydrogenative nature of the catalysts. Probable reaction pathways were proposed for N-alkylation of amines, α-alkylation of ketones and synthesis of quinolines on the basis of control experiments and detection of reaction intermediates. [ABSTRACT FROM AUTHOR]

This research study reports the synthesis, structural characterization and phenoxazinone synthase‐like activity of two structurally similar copper(II) complexes developed with a benzimidazole functionalized Schiff base (L). The ligand, L, was designed and synthesized in high yield by the reaction of p‐methoxy benzaldehyde with o‐phenylenediamine. The reaction of L with CuCl2 and Cu(NO3)2 leads to the formation of two isostructural complexes, [Cu(L)2Cl2]2 (1) and [Cu(L)2(NO3)2]2 (2). Single crystal X‐ray structural study reveals that both the Cu(II) centre in 1 and 2 adopts a square planar geometry. An attempt has also been made to understand the role of coordinated co‐ligands on the catalytic oxidation of 2‐aminophenol (2‐AP) to 2‐amino‐3H‐phenoxazine‐3‐one (2‐APX) in methanol. The presence of coordinated nitrate to Cu(II) ions imparts a more labile character to complex 2, and the catalytic efficiency (kcat/KM) for complex 2 (1.50 × 107) was determined almost double compared with that of complex 1 (8.78 × 106). Electro‐chemical and electrospray ionization mass spectrometry studies of 1 and 2 with 2‐AP suggests that the square planar geometries of the Cu(II) centres remain the driving force to develop enzyme‐substrate adducts and excellent catalytic performance of the complexes. Electrochemical and EPR spectral analysis of the reaction mixture confirm the presence of active 2‐AP−/2‐AP•− redox species in the course of catalytic oxidation and suggest the radical driven oxidative coupling of 2‐AP in an aerobic environment. Temperature‐dependent kinetic measurements were carried out to evaluate the activation parameters (Ea, ΔH‡, ΔS‡), which favours the higher rate of catalytic oxidation of 2‐AP for complex 2 than complex 1. [ABSTRACT FROM AUTHOR]

Graphical abstract Herein, the synthesis, structural characterisation and potential catalytic activity of a tetrazinc(II) complex were investigated with experimental techniques and DFT calculations. The diverse coordination aspect of methanol in the architect of the complex and it's crucial role in oxidative coupling of 2-aminophenol through ligand centred radical pathway were comprehensively ascertained. Abstract Herein, the synthesis, structural characterization and catalytic activity of a novel tetranuclear zinc(II)–Schiff base complex, [Zn 4 (L) 2 (µ 3 -OCH 3) 2 (CH 3 OH) 2 ]·2CH 3 OH (1), [ L = N,N′- bis(3-methoxysalicylidene)-1,3-diamino-2-propanol] was presented. Single crystal X-ray diffraction structural analysis revealed that the tetra-zinc(II) cluster crystallized in a monoclinic system with P 2 1 / c space group. Interestingly, three different molecular bridges (methoxido-, alkoxido- and phenoxido-) simultaneously co-existed in assembling tetra-zinc(II) core, which was a very rare observation. To the best of our knowledge, this compound would be the first compound where a diverse coordination aspect was covered by a single solvent as terminal coordinator (CH 3 OH), bridging (µ 3 -CH 3 OH) and solvent for crystallization in the existing scientific literature. The compound showed good photo-stability and excellent luminescence property with higher lifetime at transition state in ethanol. This zinc(II) complex revealed crucial role as an effective catalytic system towards oxidation of 2-aminophenol (2-AP) in ethanol. Additionally, the tetra-zinc(II) complex displayed potential phenoxazinone synthase like activity with momentous turn over number, k cat (h−1) = 6.19 × 102 in ethanol under aerobic condition. ESI-MS and EPR spectral analysis of the reaction mixture between Zn(II) complex and 2-AP recommended that the course of catalysis proceeded through substrate–catalyst adduct formation and authenticated the radical mechanistic pathway in favor of oxidative coupling product. This tetranuclear zinc(II)–Schiff base complex would be considered as the first example that catalyzed the oxidative coupling of 2-aminophenol to aminophenoxazino compound under usual aerobic condition. As complementary, detailed quantum chemical computations, performed with density functional theory (DFT) were well corroborated with the experimental results. This was the first and rarest example where a tetrazinc(II)–Schiff base cluster exhibited catalytic oxidation of 2-AP through ligand centered radical activity. [ABSTRACT FROM AUTHOR]

In this work, we present the synthesis and structural characterization of a new Zn(II)‐Schiff base complex, [Zn(L)(H2O)] (1), [L=N,N′‐bis(3‐methoxysalicylidene)‐1,3‐diamino‐2‐propanol]. Single crystal X‐ray structural analysis reveals that 1 crystallizes in monoclinic system with P21/c space group. The compound shows good photo‐luminescence property in methanol medium. This Zn(II) complex has been evaluated as a catalytic system in the catalytic oxidation of 3,5‐di‐tert‐butylcatechol (DTBC) in methanol. The Zn(II) complex displays good catecholase like activity with significant turn over, kcat(h–1)=7.99×102 in methanol under aerobic condition. Very interestingly, we are able to isolate the oxidation product as 3,5‐di‐tert‐butylquinone (2) in association with the substrate in the form of a single crystal. Electron paramagnetic resonance (EPR), electron spray ionization (ESI) mass and 1H nuclear magnetic resonance (NMR) spectral analyses of the reaction mixture between Zn(II) complex and DTBC recommend that the course of catalysis proceeds through substrate‐catalyst adduct formation & confirm the presence of radical pathways in favour of oxidation products. The computation studies have been executed with density functional theory and all experimental observations are well rationalised with extensive theoretical calculations. Being a redox inactive metal ion, catalytic oxidation of DTBC by Zn(II) complexes will always be a remarkable example in the scientific community. A new mononuclear zinc(II)‐Schiff base complex, [Zn(L)(H2O)] (1) has been synthesized and structurally characterized through different analytical techniques in support with computational studies. This Zn(II) compound exhibited catalytic oxidation of 3,5‐DTBC with a significant turn over number, 7.99×102 h−1 and recommended the radical pathways for the production of 3,5‐DTBQ product. [ABSTRACT FROM AUTHOR]

4H-Chromene derivatives are promising anticancer compounds known to bind within the colchicine binding site of the tubulin protein. Among these, the 2-amino-4-phenyl-4H-benzo[h]chromene-3-carbonitrile-based 4H-chromenes scaffold is known to produce a significant impact on tubulin proteins. Other molecules with similar pharmacophores are also known for their colchicine binding site targeting abilities. However, tubulin is not a single protein; multiple isoforms have been reported, and some are comparatively more important under malignant conditions. Therefore, the research findings presented herein include a detailed understanding of the interaction pattern of the 2-amino-4-phenyl-4H-benzo[h]chromene-3-carbonitrile series for their colchicine binding ability against various tubulin isoforms proteins. We have established the current series anticancer potential and structural activity relationship. The series revealed promising anticancer potential, and MNC-1 was the best among all. However, a serious side effect of this scaffold is a major problem, as these derivatives indiscriminately bind to the tubulin of malignant and normal cells. However, the expression profile of tubulin isoforms was found to be different in normal and malignant cell types. Therefore, selective killing of the malignant cell seems possible by designing a 4H-chromenes derivative selective against particular tubulin isoforms. The insights provided herein clearly indicate the differences in the binding pattern of different 4H-chromenes derivatives against different tubulin isoforms. Therefore, with precise structural modification, these molecules' selective targeting against cancer cells seems quite possible. [ABSTRACT FROM AUTHOR]

Summary 1. The aim of the present study was to understand the benefit of liposomal dry powder for inhalation (LDPI) of ketotifen fumarate (KF) over plain drug dry powder for inhalation as a pulmonary targetted drug-delivery system. 2. The KF liposomes, composed of egg phosphatidyl choline and cholesterol, were prepared by the lipid film hydration technique. The liposomal dispersion was freeze dried and formulated to a dry powder for inhalation. Values of 89.0–65.3% drug entrapment of freeze-dried liposomes were estimated in prepared batches. 3. Rehydrated KF liposomes formed by the hydration of LDPI or the plain KF solution was delivered to rat lungs by intratracheal instillation. Simultaneous monitoring of drug levels in the bronchoalveolar lavage and lung tissue enabled assessment of pulmonary drug disposition. 4. Cumulative drug levels in lung tissue after intratracheal administration revealed that with liposomes targetting factors were between 1.36 and 1.54. The maximal drug concentration in lung homogenate for LDPI was 42.0 µg compared with 73.6 µg for plain drug solution. 5. Similarly, the time to reach maximum drug concentration in the lung homogenate for liposomal dry powder was 9–12 h compared with 3 h for plain drug. 6. Hence, the use of LDPI of KF was found to provide desired drug levels in the lung for a long time and thereby increased pulmonary targetting 7. This is expected to enhance the therapeutic index of the drug and probably reduce the dose administered and the cost of therapy. [ABSTRACT FROM AUTHOR]

Springs and streams are essential sources of fresh water for the Himalayan population. To global and regional extents, these resources are being severely affected by climate change as well as anthropogenic activities. However, the effects of seismicity also have considerable influence on springs but are negligibly studied in that aspect. Crustal deformation, shaking, and movement of the earth's surface due to an earthquake, can modify the stream flow and water level in wells through consolidation of surficial deposits and development of new fractures. The present study addresses the effect of an earthquake on water springs in a seismically active zone. On 18 September 2011, the Sikkim Himalaya experienced a strong earthquake of magnitude (Mw) 6.9. To assess the impact of this earthquake on hydrology, we studied the springs located in the South Sikkim district, India. Our research indicates that few springs dried up following the Mw 6.9 earthquake in 2011 while some springs discharged at a higher rate than before. The springs which were dried up due to climate change were excluded in this study. Furthermore, our study suggests that in tectonically active mountain ranges, like Himalaya, an earthquake not only causes surficial deformations but also influences the hydrological framework at a regional scale. Therefore, the seismic nature of the terrain should also be considered for spring rejuvenation policies. • Impact of an earthquake on water bodies were studied. • Himalayan springs are sensitive to both climate change as well as earthquakes also. • An earthquake having magnitude Mw ≥ 5 may affect the discharge of a spring. [ABSTRACT FROM AUTHOR]

The advent of d–d type complex salts for designing smart functional materials with versatile utility inspired us to develop a novel type of M(II)–Ce(IV) complex salts [M(II) = Cu and Zn ions]. In this study, we present for the first time a holistic approach to design and prepare metal complex salts of the novel hybrid d–f block type, [Cu(bpy)2]2[Ce(NO3)6]2 (1), [Cu(phen)2(NO3)]2[Ce(NO3)6](HNO3) (2), [Zn(bpy)2(NO3)][ClO4] (3), and [Zn(phen)2(NO3)]2 [Ce(NO3)6] (4); [bpy = 2,2′-bipyridine; phen = 1,10-phenanthroline]. The intrinsic structural and morphological properties of the compounds have been revealed by employing a suite of analytical and spectroscopic methods. X-ray structural analysis reveals that the copper(II) centres in the cationic complex units of 1 and 2 adopt a highly distorted tetrahedral and a rare bicapped square pyramidal coordination geometry, respectively. The zinc(II) ions in both 3 and 4 adopt the rare bicapped square pyramidal geometry while the cerium(IV) ions in 1, 2 and 4 exist in a dodecahedral geometry. Investigation of supramolecular interactions reveals that intermolecular O⋯H and O⋯π short contacts bind the complex units in 1, while predominant π⋯π interactions, along with O⋯H and O⋯π short contacts, produce the binding force among the complex units in 2. We further employed the complex salts (1–4) to construct Schottky devices to reveal the role of these new complex salts in the charge-transport phenomenon. The carrier mobilities (μ) for salts 1–4 were determined to be 1.76 × 10−6, 9.02 × 10−6, 1.86 × 10−8, and 4.31 × 10−8 m2 V−1 s−1, with respective transit times (τ) of 439, 85, 4.17 × 103, and 1.79 × 103 ns, which suggest that complex salt 2 is the best candidate with the highest transport properties among all the complex salts. A crystal engineering perspective sheds light on the charge-transport properties of the complex salts, emphasizing the attribution of the best performance of 2 to its predominant π⋯π interactions. The synthesis of this new type of complex salts, their physicochemical properties and their charge-transport applications envisage great promise for the development of novel crystalline materials with smart functionalities. [ABSTRACT FROM AUTHOR]

The graphical abstract presents the oxidation of 3,5-di- tert -butylcatechol to 3,5-di- tert -butylquinone which is dependent on the pH of the solution. The effect of counter anion on the turnover number is also presented. • pH dependent catecholase activity. • Fe(II) complexes. • Role of counter anions on Turn Over Number. Two mononuclear Fe(II) complexes having same ligand framework, coordination geometry but different counter anions [Fe(L)]X 2 [L = N-(phenyl-pyridin-2-yl-methylene)-ethane-1,2-diamine; X = ClO 4 − (1), PF 6 − (2)] have been synthesized and crystallographically characterized. Both the complexes catalyzed catechol-quinone oxidation pH dependently. In the pH range 8.3–8.5 the suitable activity of both the complexes were found. Counter anions in the complexes played a significant role in controlling the turn over numbers of the catalytic reactions. In acetonitrile (MeCN), the turn over number for 1 was 4.99 h−1 and for 2 , it was 42.75 h−1. [ABSTRACT FROM AUTHOR]

The present study accounts on the synthesis, structural characterization, self-assembled crystalline architecture, and transesterification study of a mononuclear zinc(II) complex, [Zn(H L)(H 2 O)]·(H 2 O) (1) containing a previously reported Schiff base ligand, H 3 L = N,N ′-bis(salicylidene)-1,3-diamino-2-propanol]. • Synthesis and characterization of a tetrapyramidal zinc(II)-Schiff base complex. • Zn(II) complex crystallizes in hexagonal crystal system with P 6 1 space group. • This Zn(II) complex displays good transesterification activity with initial rate constant, 1.73 × 10−4 min−1. • Computational studies agree well with the experimental results in this course of study. The article demonstrates the synthesis, structural characterization and transesterification activity of a mononuclear zinc(II) complex, [Zn(H L)(H 2 O)]·(H 2 O) (1) containing a previously reported Schiff base ligand, H 3 L = N,N ′-bis(salicylidene)-1,3-diamino-2-propanol]. X-ray structural analysis of 1 reveals that Zn(II)-Schiff base complex crystallizes in hexagonal crystal system with P 6 1 space group and adopts a distorted tetrapyramidal geometry. Self-assembled molecular units of 1 exhibit a beautiful construction of 3D crystalline architecture through intermolecular hydrogen bond wire. Zinc(II) complex displays an enhancement of fluorescence intensity in comparison to H L in methanol medium. Catalytic behaviour of 1 towards disodium salt of 2,4-dinitrophenylphosphate (PNPP) in aqueous-methanol medium exhibits good transesterification activity with initial rate constant value of 1.73 × 10−4 min−1. Detailed DFT calculations are also employed to cope with the geometrical parameters of 1 as well as to explore the proposed catalytic mechanism of transesterification activity. [ABSTRACT FROM AUTHOR]

This research work reports the synthesis, structural characterization, computational study and bio-mimicking activity of Phenoxazinone Synthase enzyme of a new phenoxido-bridged dicopper(II)-Schiff base complex, [Cu 2 (L) 3 ]ClO 4 (1), [H L (Schiff base ligand) = (Z)-2-methoxy-6-(((2-methoxyphenyl)imino)methyl)phenol]. • Synthesis and characterization of a dicopper(II)-Schiff base complex. • The dicopper(II) complex adopts different coordination geometry for each of the copper(II) centres. • This Cu(II) complex efficiently catalyzes the oxidation of 2-aminophenol to aminophenoxazinone species. • EPR study authenticates the generation of radical species in this course of catalysis. This research article reports the synthesis, structural characterization and phenoxazinone synthase activity of a new phenoxido-bridged dicopper(II)-Schiff base complex, [Cu 2 (L) 3 ]ClO 4 (1) , [H L = (Z)-2-methoxy-6-(((2-methoxyphenyl)imino) methyl)phenol]. X-ray structure of the Cu(II) complex reveals that each of the two Cu(II) centres in 1 adopts different coordination geometries (distorted octahedral and distorted square planar) and phenoxido bridges couple two Cu(II) centres to form a dinuclear copper complex with Cu⋯Cu distance 3.182 Å. The dicopper(II) complex catalyzes the aerobic oxidation of 2-aminophenol (2-AP) to aminophenoxazinone species in acetonitrile with good turnover number, 78.14 h−1. Electro-chemical and electrospray ionization mass spectrometry analysis of 1 in presence of 2-AP ensure the involvement and key role of the copper(II) centres in formation of enzyme-substrate adduct. Subsequently, electron paramagnetic resonance study confirms the generation of radical species in the course of catalysis. Finally, density functional theoretical calculations well reproduce the experimental geometrical parameters and spectroscopic behaviours of 1 and decisively argue in favour of the proposed catalytic pathways. [ABSTRACT FROM AUTHOR]

Synthesis and structural characterization of a linkage isomer, bis(2,2′-dipyridylamine)dithiocyanato(k -S)nickel(II), [Ni(dpa) 2 (k -SCN) 2 (1) of a previously reported Ni(II) complex, [Ni(dpa) 2 (k -NCS) 2 (dpa = 2,2′-dipyridylamine; SCN = thiocyanate) has been reported herein. X-ray structural analysis of 1 reveals that Ni(II) complex crystallizes in monoclinic system with P 2 1 / c space group and exists in trans configuration. The coordination geometry for 1 adopts a tetragonal structure. Supramolecular aspects of the Ni(II) complex indicate that N atom of SCN behaves as a donor and H atom of dpa ligand acts as a receptor in growing 1D crystalline structure along b axis in solid state. The aromatic rings in 1 prefer to exist in face-centred stacking with interplanar distance of 3.426 Å and supports strongly to form self-assembled 3D crystalline architecture. Hirshfeld surface analysis further recommends this crystalline assembly in solid state. 1 exhibits promising phosphatase activity towards disodium(4-nitrophenyl)phosphate (PNPP) in aqueous-methanolic medium. The hydrolytic phosphatase efficiency for 1 is determined in terms of turnover number (k cat) as 3.38 × 104 h−1. Moreover, density functional theoretical computations closely replicate the structural parameters and spectroscopic behaviour of 1. Image 1 • Synthesis and X-ray structure of a linkage isomer, bis(2,2′-dipyridylamine)dithiocyanato(k-S)nickel(II), [Ni(dpa)2(k-SCN)2]. • The nickel(II) complex efficiently cleave PNPP with TON, 3.38 × 104 h−1. • The theoretical findings employing DFT have been well corroborated with the experimental results. [ABSTRACT FROM AUTHOR]

In pursuit of the significant contribution of copper ion in different biological processes, this research work describes the synthesis, X‐ray structure, Hirshfeld surface analysis, oxidative dimerization of 2‐aminophenol and antibacterial activity of a newly designed copper (II)‐Schiff base complex, [Cu(L)2] (1), [Schiff base (HL) = 2‐(2‐methoxybenzylideneamino)phenol]. X‐ray structural analysis of 1 reveals that the Cu (II) complex crystallizes in a cubic crystal system with Ia‐3d space group. The Cu (II) centre adopts an unprecedented tetragonal bipyramidal geometry in its crystalline phase. The Schiff base behaves as a tridentate chelator and forms an innermetallic chelate of first order with Cu (II) ion. The copper (II) complex has been tested in the bio‐mimics of phenaxozinone synthase activity in acetonitrile and exhibits good catalytic activity as evident from high turnover number, 536.4 h−1. Electrochemical analysis exhibits the appearance of two additional peaks at −0.15 and 0.46 V for Cu (II) complex in presence of 2‐AP and suggests the development of AP−/AP•− and AP•−/IQ redox couples in solution, respectively. The presence of iminobenzosemiquinone radical at g = 2.057 in the reaction mixture was confirmed by electron paramagnetic resonance and may be considered the driving force for the oxidative dimerisation of 2‐AP. The existence of a peak at m/z 624.81 for Cu (II) complex in presence of 2‐AP in electrospray ionization mass spectrum ensures that the catalytic oxidation proceeds through enzyme‐substrate adduct formation. The copper (II) complex exhibits potential antibacterial properties against few pathogenic bacterial species like Staphylococcus aureus, Enterococcus and Klebsiella pneumonia and scanning electron microscope studies consolidates that destruction of bacterial cell membrane accounts on the development of antibacterial activity. [ABSTRACT FROM AUTHOR]

Graphical abstract This paper reports a novel addition of a Schiff base as chemosensor for nickel(II) ion in a wider range of concentration. Highlights • We developed a new chemosensor for Nickel(II) ion with high selectivity & sensitivity. • Spin state switching of nickel ion by the Schiff base remains the driving force for super stable compound. • Ratiometric fluorescence changes are observed during sensing. • This sensing technique may be applied in a wider concentration range for Ni(II) ion. • This is a pH independent sensor. Abstract A novel tetradentate (N,O)-donor salen type Schiff base was designed, prepared and structurally characterized by different analytical techniques. This Schiff base ligand, (L = 2 , 2 '-((1,2 phenylenebis(methanylylidene))bis(azanylylidene))diphenol) behaved as an effective chemosensor towards Ni(II) ion with specific selectivity. The Schiff base (L) displayed a remarkable ratiometric fluorescence enhancement upon binding with Ni(II) ion in acetonitrile (ACN) medium. The L -Ni(II) solution was distinguished indisputably with the naked eye colour change and the crystal was found to be red colour. L selectively detected Ni(II) ion in presence of other competitive cations like Mn(II), Fe(II),Co(II), Cu(II), Zn(II), Cd(II) and Hg(II) ions. This simple but novel Schiff base might be used as a potential pH independent colorimetric and naked-eye chemosensor for Ni(II) ion. Most significantly, L exhibited geometry preferred selectivity towards Ni(II) ion and formed highly stable square planar Ni(II)-Schiff base complex. Single crystal X-ray diffraction study further authenticated that the nickel complex crystallized in orthorhombic system with P 2 1 2 1 2 1 space group in solid state. Density functional theory (DFT) calculations attested the experimental results very well. This sensing method could be applied in a wider concentration range and might be used as an alternative qualitative and quantitative test for the detection of Ni(II) ion in analytical chemistry. [ABSTRACT FROM AUTHOR]

In this study, water dispersible fluorescent carbon quantum dot (CQD) has been synthesised, having an average size of 8.6 ± 0.4 nm using Cynodon dactylon (CD) following microwave assisted green synthetic one-step method. As-prepared CQD fluoresces strongly at 444 nm having a quantum yield of 1% in water when excited at 350 nm. This fluorescence of CQD is sensitive toward As3+ and Fe3+ metal ions. These CQD are utilized for dual metal ion fluorescence sensing; turn-on fluorescence sensing for As3+ and turn-off fluorescence sensing for Fe3+ ions. Limit of detection for As3+ and Fe3+ ions has been found to be 19 nM and 0.10 μM respectively, which is the lowest value reported for As3+ without any functionalization. The adsorption kinetics of As3+ and Fe3+ ions on CQD have been examined using pseudo-first-order-kinetic model revealing that physical adsorption is dominant over chemical processes in this work. For 0.41 g/L and 1.90 g/L dose of CQD, the equilibrium adsorption capacity was found to be 1.57 × 10−6 mg/g, 2.91 × 10−7 mg/g, and 1.01 × 10−5 mg/g, 1.69 × 10−6 mg/g respectively for As3+ and Fe3+ ions. Despite having low quantum yield in water, as-prepared CQD showed low cytotoxicity and good tolerance against photodegradation of biological cells at concentrations lower than 62.5 μg/mL and when the cells are illuminated up to 12 h. Owing to this, the synthesised CQD have been utilized as fluorescent probes for in itro cell imaging. [Display omitted] • Fluorescent carbon quantum dot (CQD) were prepared using Cynodon dactylon. • CQD showed dual sensitivity, turn-off and turn-on sensing of Fe3+ and As3+ ions. • Adsorption capacity of CQD on Fe3+ and As3+ ions were examined. • Good biocompatibility and low cytotoxicity of CQD enabled in vitro cell imaging. • First report on the detection of As3+ ions using CQD without functionalization. [ABSTRACT FROM AUTHOR]

In this work, we have developed a new one-dimensional cadmium(II) coordination polymer, [Cd(phen)(NO 3 ) 2 (H 2 O)] n ( 1 ) (phen = 1,10-phenanthroline) and structurally characterized by different spectroscopic techniques including single crystal X-ray diffraction analysis. Single crystal X-ray structural analysis of 1 indicates that Cd(II) ion in the coordination polymer crystallizes in a monoclinic system with P 2 1 space group and adopts a distorted pentagonal bipyramidal coordination geometry. This will be the first citation of a 1D Cd(II) polymer till date where nitrate ions exhibit diverse coordination motifs. Solid state emission suggests good luminescence behavior of the polymer. Spectroscopic studies reveal that the polymer is unstable in polar solvents and dominates in monomeric form. Molar conductivity and electrospray ionization mass spectral analysis in methanolic solution confirm the instability of the polymer at room temperature and authenticates the decomposition of the polymer into monomer in solution. In addition, all the structural parameters and spectroscopic behaviors have been well corroborated with the theoretical findings. [ABSTRACT FROM AUTHOR]

Docetaxel has always attracted the researchers owing to its promises and challenges. Despite marked efficacy, concerns like poor aqueous solubility, lower bioavailability, poor tissue penetration and dose related side-effects offer further scope of research on docetaxel. The present study aims to explore the potential of C 60 -fullerenes in the delivery of docetaxel to cancerous cells. C 60 -fullerenes were carboxylated, acylated and conjugated with the drug. The chemical processes were monitored by UV, FT-IR and NMR spectroscopy. The conjugate was further characterized for drug loading, micromeritics, drug release, morphology and evaluated for in-vitro cytotoxicity, haemolysis and in-vivo pharmacokinetic profile. The developed nanoconstruct was able to enhance the bioavailability of docetaxel by 4.2 times and decrease the drug clearance by 50%. The developed system was able to control the drug release and was found to be compatible with erythrocytes. The cytotoxic potential on studied MCF-7 and MDA-MB231 cell lines was also enhanced by many folds, indicating marked promise in efficacy enhancement and dose reduction. The present findings are encouraging and offer a technique to enhance the delivery and efficacy potential of anticancer agents, especially belonging to BCS class IV. [ABSTRACT FROM AUTHOR]

[Display omitted] • "Nature-to-new" as a medicinal chemistry strategy. • Iterative Scaffold-hopping to identify new chemotype. • Organocatalysed Umpolung Chemistry to construct Arylidene heterocyclic-fused imidazolone scaffold. • Polyphosphoric acid-mediated ester-lactam exchange. • In silico study reveals good drug-like properties. A strategy of "Nature-to-new" with iterative scaffold-hopping was considered for investigation of privileged ring/functional motif-elaborated analogs of natural aurones. An organocatalyzed umpolung chemistry based method was established for molecular-diversity feasible synthesis of title class of chemotypes i.e. (Z)-2-Arylideneimidazo[1,2– a ]pyridinones and (Z)-2-Arylidenebenzo[ d ]imidazo[2,1–b]thiazol-3-ones. Various biophysical experiments indicated their important biological properties. The analogs showed characteristic anticancer activities with efficiency more than an anticancer drug. The compounds induced apoptosis with arrest in the S phase of the cell cycle regulation. The compounds' significant effect in up/down-regulation of various apoptotic proteins, an apoptosis cascade, and the inhibition of topoisomerases-mediated DNA relaxation process was identified. The analysis of the structure-activity relationship, interference with biological events and the drug-likeness physicochemical properties of the compounds in the acceptable window indicated distinctive medicinal molecule-to-properties of the investigated chemotypes. [ABSTRACT FROM AUTHOR]

• Synthesis and characterization of a copper(II) complex. • Solvent induced distortion to the coordination environment of Cu(II) centre. • Bio-mimics of catecholase activity with high turnover number, 4.75 × 102 h–1. • Exploitation of fungicidal and anti-proliferative property. This research work reports the synthesis, single crystal X-ray structure, catechol oxidation, fungicidal and antiproliferative activity of a newly synthesized copper(II) complex, [Cu(L) 2 ]H 2 O . CH 3 OH (1) containing an azo-functionalized Schiff base, H L = 2-methoxy-6-((Z)-((4-((E)-phenyldiazenyl)phenyl)imino)methyl)phenol. The crystal structure analysis reveals that the Cu(II) centre exists in a highly distorted square planar geometry. The crystallize water and methanol form a strong intermolecular association through H-bonding. More importantly, the H atoms of the lattice water interact with the O atoms of ligand units leading to 5- and 6-membered cycles through the H-bonding network and distort the square planar geometry. The copper(II) complex has emerged as a bioinspired catalyst in the oxidative transformation of 3,5-di- tert -butylcatechol (DTBC) to o-benzoquinone in methanol with a high turnover number, 4.75 × 102 h–1. Electrochemical analysis of the copper(II) complex in presence of DTBC recommends the generation of catechol/o-benzosemiquinone redox couple in the course of oxidation. The EPR spectral analysis of 1 in presence of DTBC was found silent and suggested the antiferromagnetic interaction between copper centre and benzosemiquinone species. The copper(II) complex turns out to be a potential fungicidal agent against clinical candida albicans and scanning electron microscope studies confirm the destruction of the fungal cell membrane with the deposition of copper. The IC 50 value of the copper complex was determined as 15 µg/mL which suggests the excellent antiproliferative potency of the synthetic compound against the breast cancer cell lines, MCF-7. [Display omitted] [ABSTRACT FROM AUTHOR]

Two hydrazine functionalized Schiff bases have been synthesized through the reaction between hydrazine and o -vanillin/salicylaldehyde compounds employing a green-chemical approach and characterized spectroscopically including XRD study. Crystal structure analysis reveals that both the chemosensors, N,N′ -bis(o -vanilidine)hydrazine (P17) and N,N′ -bis(salicylidene)hydrazine, (HARB) crystallize in monoclinic system with P 2 1 / n space group and exist in the locked forms through intramolecular H-bonding (~1.90 Å) between phenolic-OH and N atom of hydrazine. The chemosensors display excellent selectivity towards fluoride followed by bisulphate ions, over other potential competitor anions in acetonitrile. Binding stoichiometry of the individual chemosensor with F− is confirmed to be 1:1 and assessed with absorption study and 1H NMR analysis. Systematic DFT analysis reveals that the contribution of hydroxyl oxygen atoms to the HOMO increases sharply from the chemosensor to chemosensor–F− adduct (17% to 28%) leading to deprotonation of one hydroxyl group and consequently involvement in conjugation impeding the C=N isomerisation. Thus, the hydroxyl proton captured by F− restricts the C=N isomerisation as well as ICT character of both the chemosensors and confirms the cascade sensing mechanism for fluoride and bisulphate ions. This paper reports the green-chemical synthesis of hydrazine functionalized Schiff base, their crystal structures and cascade detection of fluoride followed by bisulphate ions over other competitive anions in acetonitrile in a wider range of concentration. Unlabelled Image • We developed hydrazine functionalised chemosensors for cascade detection of F− and HSO 4 − ion with high selectivity & sensitivity. • The hydroxyl proton captured by F− restricts the C=N isomerisation for the chemosensors. • DFT calculations suggests that the contribution of hydroxyl oxygen atoms to HOMO leads to deprotonation of hydroxyl group. • This sensing technique may be applied in a wider concentration range. • This is a pH independent sensor. [ABSTRACT FROM AUTHOR]

This research work demonstrates the synthesis, crystal structure, supramolecular architecture, 4-methylcatechol oxidation and bactericidal activity of a newly designed zinc complex containing a protonated Schiff base of zwitter ion type. • Synthesis and crystal structure of a tetrahedral zinc-Schiff base complex. • Schiff base gets protonated to exhibit monodentate behaviour. • The zinc complex exhibits good efficiency towards the bio-mimetic oxidation of 4-methylcatechol. • Radical driven catalytic activity has been observed. • Shows good bactericidal activity with 1.44% presence of zinc in cell membrane of bacteria. Focusing on the important biological functions of metallo-enzymes and metallo-therapeutics in living world, this research work demonstrates the synthesis, crystal structure, supramolecular architecture, 4-methylcatechol oxidation and bactericidal activity of an interesting zinc-Schiff base complex, [Zn(H L) 2 Cl 2 ] (1), [Schiff base (H L) = 2-(2-methoxybenzylideneamino)phenol]. Crystal structure analysis of the zinc-Schiff base reveals that zinc centre exists in a distorted tetrahedral geometry. The Schiff base adopts three donor centres, however it gets protonated to exist in a zwitter ionic form and behaves as a monodentate coordinator in 1. This zinc-Schiff base complex has been examined towards the bio-mimetic oxidation of 4-methylcatechol (4-MC) in methanol and portrays its good efficacy with good turnover number, 1.45 × 103 h−1. Electro-chemical study, electron paramagnetic resonance analysis and electrospray ionization mass spectrometry results for the zinc-Schiff base complex in presence of 4-MC ensures that the catalytic reaction undergoes through enzyme-substrate binding, and generation of radical in the course of catalysis drives the catalytic oxidation of 4-MC. Antibacterial study has also been performed against few clinical pathogens (Bacillus SP, Enterococcus , and E. coli). Scanning electron microscope and EDAX analysis for the pathogen with little dose of zinc complex confirms the destruction of bacterial cell membrane with 1.44% occurrence of zinc in the selected zone of inhibition area. This observation holds a great promise to develop future antibacterial agent. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we have synthesised and structurally characterized a mononuclear cobalt(III) complex, [Co(2-O-pn)2]Cl.2H2O (1), (2-O-pn = 1,3-diamino-2-propanolate). From the X-ray structure of the cobalt complex, it is revealed that Co(III) ion in 1 adopts an octahedral geometry and crystallizes in the monoclinic system with C2 / c space group. The lattice aqua molecule in combination with chloride ion in 1 forms a water-chloride cluster, (H2O)2⋯(Cl)2 through strong H-bonding interaction mediated via cobalt(III) complex in a unique binding motif. This cobalt(III) complex has been tested as an effective catalytic system towards the oxidative coupling of 2-aminophenol (2-AP) in the MeCN medium. In situ mass spectral analysis confirms that 2-AP forms an adduct with cobalt ion and the course of catalysis proceeds through catalyst-substrate binding followed by oxidative coupling of 2-AP with iminobenzoquinone. This cobalt(III) catalyst affords exclusively aminophenoxazinone species with a significant turnover number, kcat:6.37×102h-1 in the MeCN medium. This cobalt(III) complex is able to screen out the growth of some bacteria and fungi species. Quantum chemical calculations employing density functional theory is used to model structural parameters and spectroscopic behaviour. The theoretical findings corroborate well with the experimental results.GRAPHICAL ABSTRACT: SYNOPSIS A mononuclear cobalt(III) complex exhibits significant catalytic efficacy towards oxidative coupling of 2-aminphenol (2-AP) in MeCN medium and predominantly produces aminophenoxazinone species with a significant turn over number, kcat:6.37×102h-1 in presence of molecular oxygen. [ABSTRACT FROM AUTHOR]