Self-assembled Co(II) and Co(III) [ML] helicates and [ML] tetrahedra from an unsymmetrical quaterpyridine ligand.

In order to bind guest molecules with exquisite selectivity, biological host molecules often employ low symmetry binding pockets. The majority of metallosupramolecular assemblies, however, rely on symmetrical ligands to form high-symmetry assemblies that enclosing similarly symmetrical cavities. Here we employ an unsymmetrical quaterpyridine ligand in combination with cobalt(II) to form a mixture of low-symmetry [ML] helicates and [ML] tetrahedra and their subsequent oxidation to Co(III)-containing assemblies.

Remote stereocentres do not disrupt the stereochemical coupling in homochiral [ML] helicates and [ML] tetrahedra.

Despite the use of achiral ligands, the vast majority of metallosupramolecular assemblies containing octahedral tris-bidentate metal centres show strong stereochemical communication between metal centres, generally resulting in homochiral assemblies even though they are statistically disfavoured. Here we show that when resolved stereocentres are attached to the central part of a quaterpyridine ligand, the stereochemical coupling from this centre is insufficient to disrupt the strong stereochemical communication between metal centres in both [ML] helicates and [ML] tetrahedra.

Antiplatelet, cytotoxic activities and characterization of green-synthesized zinc oxide nanoparticles using aqueous extract of Nephrolepis exaltata.

The goal of the current study was to synthesize zinc oxide nanoparticles (ZnO-NPs) using ZnCl.2HO salt precursor and an aqueous extract of Nephrolepis exaltata (N. exaltata), which act as a capping and reducing agent.

Facile Synthesis of PdO.TiO Nanocomposite for Photoelectrochemical Oxygen Evolution Reaction.

The rapid depletion of fossil fuels and environmental pollution has motivated scientists to cultivate renewable and green energy sources. The hydrogen economy is an emerging replacement for fossil fuels, and photocatalytic water splitting is a suitable strategy to produce clean hydrogen fuel. Herein, the photocatalyst (PdO.

Sterics and metal-ion radius control the self-assembly of [ML] helicates.

The interplay of many factors influences the outcomes of self-assembly reactions. Using an acetylene-appended quaterpyridine ligand we show that both the size of the metal ion and the presence of steric repulsion between the acetylene groups result in the exclusive formation of [ML] helicates rather than a helicate/tetrahedron equilibrium.

Controlling the Complexity and Interconversion Mechanisms in Self-Assembled [Fe L ] Helicates and [Fe L ] Cages.

Self-assembled coordination cages and metal-organic frameworks have relied extensively on symmetric ligands in their formation. Here we have prepared a relatively simple system employing an unsymmetric ligand that results in two distinct self-assembled structures, a [Fe L ] helicate and a [Fe L ] cage composed of 10 interconverting diastereomers and their enantiomers. We show that the steric profile of the ligand controls the complexity, thermodynamics and kinetics of interconversion of the system.

The kinetics and mechanism of interconversion within a system of [FeL] helicates and [FeL] cages.

Nature builds simple molecules into highly complex assemblies, which are involved in all fundamental processes of life. Some of the most intriguing biological assemblies are those that can be precisely reconfigured to achieve different functions using the same building blocks. Understanding the reconfiguration of synthetic self-assembled systems will allow us to better understand the complexity of proteins and design useful artificial chemical systems.

Insights into the growth of bismuth nanoparticles on 2D structured BiOCl photocatalysts: an in situ TEM investigation.

The synthetic techniques for novel photocatalytic crystals had evolved by a trial-and-error process that spanned more than two decades, and an insight into the photocatalytic crystal growth process is a challenging area and prerequisite for achieving an excellent photoactivity. Bismuth nanoparticle based hybrids, such as Bi/BiOCl composites, have recently been investigated as highly efficient photocatalytic systems because of the localized surface plasmon resonance (LSPR) of nanostructured bismuth. In this work, the observation towards the formation and growth of bismuth nanoparticles onto 2D structured BiOCl photocatalysts has been performed using a transmission electron microscope (TEM) directly in real time.

Synthesis, morphology and antifungal activity of nano-particulated amphotericin-B, ketoconazole and thymoquinone against Candida albicans yeasts and Candida biofilm.

In the current study, nano-particulated drugs-Amphotericin-B, Ketoconazole and Thymoquinone (an active ingredient of Nigella sativa)-were prepared using the ball milling technique, and their particle sizes were examined by transmission electron microscopy (TEM) and using a particle size analyzer. The grain sizes of the prepared compounds were found in between 5 to 20 nm, and exhibited quasi-spherical morphology. The antifungal activity of each nano-particulated drug was investigated in vitro against Candida albicans yeasts and Candida biofilm, and compared with their micro-structured conventional forms.