Mild Homogeneous Synthesis of Gold Nanoparticles through the Epoxide Route: Kinetics, Mechanisms, and Related One‐Pot Composites

A new one-pot homogeneous methodology at room temperature to obtain Au nanoparticles (AuNP) on the basis of the epoxide route is presented. The proposed method takes advantage of the homogenous generation of OH- moieties driven by epoxide ring-opening, mediated by chloride nucleophilic attack. Once reached alkaline conditions, the reducing medium allows the quantitative formation of AuNP under well-defined kinetic control. A stabilizing agent, such as polyvinylpyrrolidone (PVP) or cetyltrimethylammonium chloride (CTAC), is required to maintain the AuNP stable. Meanwhile their presence dramatically affects the reduction kinetics and pathway, as demonstrated by the evolution of the UV/Vis spe…

On Demand One-Pot Mild Preparation of Layered Double Hydroxides and Their Hybrid Forms: Advances through the Epoxide Route.

Epoxide ring opening driven alkalinization process was explored with the aim of preparing layered double hydroxide (LDH) phases on demand, at room temperature. Employing iodide as nucleophilic agent, the precipitation reaction can be driven under much lower halide concentrations. This scenario favors the selective intercalation of concomitant bulky oxo anions as nitrate or perchlorate in the LDH products, allowing for the one-pot synthesis of an LDH able to delaminate in formamide. Even large dicarboxylic acids, - O2 C-(CH2 )n -CO2 - , with n up to 8, can be quantitively intercalated within the growing LDH phase, providing a versatile one-pot route for hybrid LDHs as well. Under the mild co…

The Missing Link in the Magnetism of Hybrid Cobalt Layered Hydroxides: The Odd‐Even Effect of the Organic Spacer

A dramatic change in the magnetic behaviour, which solely depends on the parity of the organic linker molecules, has been found in a family of layered CoII hydroxides covalently functionalized with dicarboxylic molecules. These layered hybrid materials have been synthesized at room temperature using a one-pot procedure through the epoxide route. While hybrids connected by odd alkyl chains exhibit coercive fields (Hc) below ca. 3500 Oe and show spontaneous magnetization at temperatures (TM) below 20 K, hybrids functionalized with even alkyl chains behave as hard magnets with Hc>5500 Oe and display a TM higher than 55 K. This intriguing behaviour was studied by density functional theory with …

Unveiling the Occurrence of Co(III) in NiCo Layered Electroactive Hydroxides: The Role of Distorted Environments

Co- and Ni-based layered hydroxides constitute a unique class of two-dimensional inorganic materials with exceptional chemical diversity, physicochemical properties and outstanding performance as supercapacitors and overall water splitting catalysts. Recently, the occurrence of Co(III) in these phases has been proposed as a key factor that enhance their electrochemical performance. However, the origin of this centers and control over its contents remains as an open question. We employed the Epoxide Route to synthesize a whole set of α-NiCo layered hydroxides. The PXRD and XAS characterization alert about the occurrence of Co(III) as a consequence of the increment in the Ni content. DFT+U si…

Room temperature synthesis of lanthanum phosphates with controlled nanotexture as host for Ln(III) through the Epoxide Route

AbstractHerein, the Epoxide Route, a one-pot room temperature alkalinization method based on the reaction between a nucleophile and an epoxide, has been employed to synthesize LaPO4 in the form of a Rhabdophane phase. The intrinsic features of this synthetic approach allow the reaction to be followed by pH monitoring, making possible the identification of the different precipitation steps involved in the formation of the solid. Once demonstrated the effectiveness of this chemical methodology, the size and shape of the LaPO4 particles were controlled by varying the identity and proportion of the organic co-solvents employed to perform the reaction. By these means, crystalline particles with …

Amorphous Calcium Phosphates: Solvent-Controlled Growth and Stabilization through the Epoxide Route.

Calcium phosphates stand among the most promising nanobiomaterials in key biomedical applications, such as bone repairment, signalling or drug/gene delivery. Their intrinsic properties as crystalline structure, composition, particle shape and size define their successful use. Among these compounds, metastable amorphous calcium phosphate (ACP) is currently gaining particular attention due to its inherently high reactivity in solution, which is crucial in bone development mechanisms. However, the preparation of this highly desired (bio)material with control over its shape, size and phase purity remains as a synthetic challenge. In this work, the epoxide route was adapted for the synthesis of …

Halide-Mediated Modification of Magnetism and Electronic Structure of α-Co(II) Hydroxides: Synthesis, Characterization, and DFT+U Simulations.

The present study introduces a comprehensive exploration in terms of physicochemical characterization and calculations based on density functional theory with Hubbard's correction (DFT+U) of the whole family of α-Co(II) hydroxyhalide (F, Cl, Br, I). These samples were synthesized at room temperature by employing a one-pot approach based on the epoxide route. A thorough characterization (powder X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetric analysis/mass spectroscopy, and magnetic and conductivity measurements) corroborated by simulation is presented that analyzes the structural, magnetic, and electronic aspects. Beyond the inherent tendency of intercalated anions to …

Cover Feature: The Missing Link in the Magnetism of Hybrid Cobalt Layered Hydroxides: The Odd–Even Effect of the Organic Spacer (Chem. Eur. J. 3/2021)