Heterobi- and multimetallic complexes providing close proximity between several metal centers serve as active species in artificial and enzymatic catalysis, and in model systems, showing unique modes ...of metal-metal cooperative bond activation. Through the rational design of well-defined, unsymmetrical ligand scaffolds, we create a convenient approach to support the assembly of heterometallic species in a well-defined and site-specific manner, preventing them from scrambling and dissociation. In this perspective, we will outline general strategies for the design of unsymmetrical ligands to support heterobi- and multimetallic complexes that show reactivity in various types of heterometallic cooperative bond activation.
Unsymmetrical ligand scaffolds bridging two or more different metals in a site-selective manner offer a convenient approach to utilize metal-metal cooperation for bond activation.
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•Photo, electro-Fenton and photo-electro-Fenton processes were compared for the removal of % color and COD from landfill leachate.•Photo-electro-Fenton process yielded higher % color ...and COD removal with low power consumption than the photo and electro-Fenton process.•Operating parameters were studied to obtain the process efficiency.•Direct and alternating current photo-electro-Fenton process was studied.
The comparison of photo (UV), electro-Fenton and photo-electro-Fenton process on the removal of % color and chemical oxygen demand (COD) along with power consumption on landfill leachate wastewater was investigated. Experimental results showed that, the hybrid photo-electro-Fenton process yielded higher color (100%) and COD (97%) removal efficiencies with lower power consumption (3.10 kWhr/m3) than the photo and electro-Fenton processes alone. Effect of major operating parameters such as current density (0.07–0.35 A/dm2), solution pH (1.5–5), inter-electrode distance (0.75–3 cm), hydrogen per oxide (H2O2) concentration (75–450 mg/L), COD concentration (1000–5000 ppm) and UV power (8–32 W) on the % COD removal efficiency and power consumption of landfill leachate were investigated. The direct and alternating current photo-electro-Fenton process was studied and reported on the % COD removal and power consumption. The alternating current photo-electro-Fenton process is most suitable in comparison to the direct current photo-electro-Fenton process and can be applied effectively and efficiently for the removal of pollutant from wastewater.
Aminoquinonato bridged Re(I)-based metallarectangles have been constructed via an orthogonal bonding approach. Self-assembly of Re2(CO)10 and aminoquinone ligands in the presence of ditopic linear ...pyridyl ligands has resulted in the formation of metallarectangles of the general formula {(CO)3Re(μ-η4-L)Re(CO)3}2(μ-N-L′-N)2 (1–4), wherein 1, L = 2,5-bis(n-butylamino)-1,4-benzoquinonato (bbbq) and N-L′-N = 4,4′-bipyridine (bpy); 2, L = 2,5-bis(phenethylamino)-1,4-benzoquinonato (bpbq) and N-L′-N = 4,4′-bipyridine; 3, L = 2,5-bis(n-butylamino)-1,4-benzoquinonato (bbbq) and N-L′-N = trans-1,2-bis(4-pyridyl)ethylene (bpe) and 4, L = 2,5-bis(phenethylamino)-1,4-benzoquinonato (bpbq) and N-L′-N = trans-1,2-bis(4-pyridyl)ethylene (bpe). Metallarectangles 1–4 have been characterized by elemental analysis, IR, NMR, and UV–vis absorption spectroscopic techniques. The molecular structures of 1 and 4 were determined by single-crystal X-ray diffraction methods. The molecular recognition capability of 1 and 3 with pyrene and triphenylene has been investigated using UV–vis absorption and emission spectroscopic techniques. The formation of host–guest complex has been further corroborated by the single-crystal X-ray structural evidence of carceplex system (3⊃pyrene)·(DMF).
India has a rich tradition of plant-based knowledge on healthcare. A large number of plants/plant extracts/decoctions or pastes are equally used by tribals and folklore traditions in India for ...treatment of cuts, wounds, and burns. The present review thus attempts to analyze the ethnobotanical knowledge base for treatment of cuts and wounds which includes a usage of plants, methods employed by tribals and folklore practices prevailing in India. Pharmacological reports available on Indian medicinal plants employing various wound healing models and its underlying molecular mechanism, wherever available, has also been briefly reviewed. This pharmacological validation on Indian medicinal plants is very limited and a large number of plants used in tribal and folklore with enormous potential have not been validated for their wound healing activity. This review therefore attempts to bridge the lacunae in the existing literature and offers immense scope for researchers engaged in validation of the traditional claims and development of safe and effective and globally accepted herbal drugs for cuts and wounds.
The disease preventive and health promotive approach of ‘Ayurveda’, which takes into consideration the whole body, mind and spirit while dealing with the maintenance of health, promotion of health ...and treating ailments is holistic and finds increasing acceptability in many regions of the world. Ancient Ayurvedic physicians had developed certain dietary and therapeutic measures to arrest/delay ageing and rejuvenating whole functional dynamics of the body system. This revitalization and rejuvenation is known as the ‘Rasayan chikitsa’ (rejuvenation therapy). Traditionally, Rasayana drugs are used against a plethora of seemingly diverse disorders with no pathophysiological connections according to modern medicine. Though, this group of plants generally possesses strong antioxidant activity, only a few have been investigated in detail. Over about 100 disorders like rheumatoid arthritis, hemorrhagic shock, CVS disorders, cystic fibrosis, metabolic disorders, neurodegenerative diseases, gastrointestinal ulcerogenesis and AIDS have been reported as reactive oxygen species mediated. In this review, the role of free radicals in these diseases has been briefly reviewed. ‘Rasayana’ plants with potent antioxidant activity have been reviewed for their traditional uses, and mechanism of antioxidant action. Fifteen such plants have been dealt with in detail and some more plants with less work have also been reviewed briefly.
Facile transmetalation is observed from a d8 metal, platinum(ii), to indium and gallium leading to the extrusion of methylated gallate and indate anions representing a rare case of the “reverse” ...transmetalation from a d8 metal to a main group metal. The Pt–Ga and Pt–In bonding in the bimetallic complexes was analyzed through bosonic and fermionic potentials, QTAIM, and NBO.
Nickel perfluoroethyl and perfluoropropyl complexes supported by naphthyridine-type ligands show drastically different aerobic reactivity from their trifluoromethyl analogs resulting in facile oxygen ...transfer to perfluoroalkyl groups or oxygenation of external organic substrates (phosphines, sulfides, alkenes and alcohols) using O
2
or air as a terminal oxidant. Such mild aerobic oxygenation occurs through the formation of spectroscopically detected transient high-valent Ni
III
and structurally characterized mixed-valent Ni
II
-Ni
IV
intermediates and radical intermediates, resembling O
2
activation reported for some Pd dialkyl complexes. This reactivity is in contrast with the aerobic oxidation of naphthyridine-based Ni(CF
3
)
2
complexes resulting in the formation of a stable Ni
III
product, which is attributed to the effect of greater steric congestion imposed by longer perfluoroalkyl chains.
Aerobic oxidation of long-chain perfluoroalkyl Ni complexes results in O-atom transfer to form perfluorocarboxylates
via
high valent Ni; in the presence of external substrate, oxygenation of phosphines, sulfides, stilbenes or alcohols occurs.
Herein, we describe the first transition-metal-free catalytic carboalkoxylation of styrenes with aryl diazonium salts by Meerwein addition in the presence of a phenalenyl ligand at room temperature ...without requiring any light stimulation. This three-component reaction allows facile difunctionalization of styrene derivatives with various alcohols (such as 1, 2, and 3°) as the source of alkoxy group during this transformation. The key intermediates and the transition states involved in this reaction path were unraveled by a series of control experiments coupled with density functional theory calculations. The full mechanistic investigation provides an understanding of the selectivity toward carboalkoxylation (Meerwein arylation addition elimination) in the presence of various alcohols over the simple arylation to multiple bond (Meerwein arylation–elimination) reaction.
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