The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.201906064.Research on artificial photoactivated molecular machines has moved in recent years from a basic scientific endeavor toward a more applicative effort. Nowadays, the prospect of reproducing the operation of natural nanomachines with artificial counterparts is no longer a dream but a concrete possibility. The progress toward the construction of molecular-machinebased devices and materials in which light irradiation results in the execution of a task as a result of nanoscale movements is illustrated here. After a brief description of a few basic types of photoactivated molecular machines, significant examples of their exploitation to perform predetermined functions are presented. These include switchable catalysts, nanoactuators that interact with cellular membranes, transporters of small molecular cargos, and active joints capable of mechanically coupling molecular-scale movements. Investigations aimed at harnessing the collective operation of a multitude of molecular machines organized in arrays to perform tasks at the microscale and macroscale in hard and soft materials are also reviewed. Surfaces, gels, liquid crystals, polymers, and self-assembled nanostructures are described wherein the nanoscale movement of embedded molecular machines is amplified, allowing the realization of muscle-like actuators, microfluidic devices, and polymeric materials for light energy transduction and storage.

Simple ammonium and pyridinium perrhenate salts were evaluated as catalysts for the deoxydehydration (DODH) of diols into alkenes.

Well-defined dinuclear lanthanide complexes: stabilisation of both CeIII and CeIV.

A palladium N-heterocyclic carbene catalyzed methodology for the synthesis of substituted, N-unprotected indoles and azaindoles is reported. The protocol permits access to various, highly substituted members of these classes of compounds. Although two possible reaction pathways (deprotonative and Heck-like) can be proposed, control experiments, supported by computational studies, point toward a deprotonative mechanism being operative.

A hybrid epoxy resin with intrinsic self healing properties has been prepared from a bifunctional Diels-Alder (DA) adduct. The obtained network, based on conventional Diglycidyl ether of Bis-phenolA (DGEBA) and DA epoxy, leads to simultaneous tuning of physical-chemical properties and healing capability. The self-repairing behavior has been verified by means of scratch recovery observation and micromechanical analysis. A satisfactory morphological and mechanical recovery has been achieved by thermal stimulus, leading to very promising application in the field of adhesives and structural applications.

The oxygenation of aliphatic and aromatic hydrocarbons using earth-abundant Fe and Cu catalysts and "green" oxidants such as hydrogen peroxide is becoming increasingly important to atom-economical chemical processing. In light of this, we describe that dinuclear Cu complexes of pyrrolic Schiff-base macrocycles, in combination with ferric chloride (FeCl), catalyze the oxygenation of π-activated benzylic substrates with hydroperoxide oxidants at room temperature and low loadings, representing a novel design in oxidation catalysis. Mass spectrometry and extended X-ray absorption fine structure analysis indicate that a cooperative action between Cu and Fe occurs, most likely because of the interaction of FeCl or FeCl with the dinuclear Cu macrocycle. Voltammetric measurements highlight a modulation of both Cu and Fe redox potentials in this adduct, but electron paramagnetic resonance spectroscopy indicates that any Cu-Fe intermetallic interaction is weak. High ketone/alcohol product ratios, a small reaction constant (Hammett analysis), and small kinetic isotope effect for H-atom abstraction point toward a free-radical reaction. However, the lack of reactivity with cyclohexane, oxidation of 9,10-dihydroanthracene, oxygenation by the hydroperoxide MPPH (radical mechanistic probe), and oxygenation in dinitrogen-purge experiments indicate a metal-based reaction. Through detailed reaction monitoring and associated kinetic modeling, a network of oxidation pathways is proposed that includes "well-disguised" radical chemistry via the formation of metal-associated radical intermediates.

The design of ligands that can act as platforms for the controlled, "bottom-up" synthesis of transition-metal clusters is a promising approach to accessing enzymatic mimics and new small-molecule reaction chemistry. This approach is exemplified here through the coordination chemistry of two compartmental Schiff-base calixpyrroles (H 4 L) that usually act as dinucleating ligands for transition metals. While reactions between H 4 L and Zn{N(SiMe 3 ) 2 } 2 form the expected dinuclear Zn "Pacman" complexes Zn 2 (L), reactions with ZnEt 2 result in the tetranuclear Zn alkyl complexes Zn 4 Et 4 (THF) 4 (L), in which open, "bowl-shaped" structures are adopted due to the flexibility of the macrocyclic platform. The outcome of hydrolysis reactions of these tetranuclear complexes is found to depend on the macrocyclic cavity size, with the smaller macrocycle favoring oxo formation in Zn 4 (μ 4 -O)Et 2 (L) and the larger macrocycle favoring complete hydrolysis to form the hydroxide-bridged cluster Zn 4 (μ 2 -OH) 4 (L). This latter complex reacts with carbon dioxide at elevated temperature, reforming the free macrocycle H 4 L and eliminating ZnCO 3 .

Abstract:The synthesis, metalation, and redox properties of an acyclic bis(iminothienyl)methene L − are presented. This π-conjugated anion displays pronounced redox activity, undergoing facile oneelectron oxidation to the acyclic, metal-free, neutral radical L • on reaction with FeBr2. In contrast, reaction of L − with CuI forms the unique, neutral Cu2I2(L • ) complex of a ligand-centered radical, whereas reaction with the stronger oxidant AgBF4 forms the metalfree radical dication L •2+ .Since the first reports on dithiolate metal complexes, [1] interest in redox-active ligands has burgeoned due to their relevance to enzymatic processes [2] and access to unusual chemical properties by coupling the redox activity of the ligand to the coordination chemistry of a metal. [3] In these cases, the ligand is no longer a classical "spectator", [4] and a large number of ligands have been shown to exhibit redox activity and stabilize the radical species through an inductive effect or by delocalization in a conjugated π-system. Accordingly, we have shown that an N-donor-expanded dipyrrin ligand [5] is redox active and able to mediate sequential electron transfer to a uranyl(VI) center (Figure 1). The initial reduction occurs at the ligand, forming a U(VI) ligand-centered radical prior to reduction of the uranium center, ultimately to U(IV). [6] Ligandcentered oxidation was also seen in Ni complexes of a similar bis(phenolate)dipyrrin ligand, with the one-electron oxidation product characterized as a ligand-centered radical. [7] In contrast to the nitrogen-containing heterocycles found in dipyrrins, porphyrinoids and sub-porphyrins, [8] studies on the redox activity of sulfur-containing heterocycles such as thiophene are more limited, despite their use in tuning the electronic properties of molecular compounds [9] and polymeric materials. [10] Expanded porphyrinoids featuring five thiophene units undergo single-electron oxidations, from the aromatic mono-anion to an isolable, air-stable neutral radical, and further to an anti-aromatic mono-cation. [11] In contrast, radical cations of simple thiophenes or their analogues are stable only at low temperatures or their identity inferred from quenching reactions. [12,13] We were keen to see if we could exploit redox activity and the 'softer' donor properties of the sulfur atoms in methylene-bridged thiophenes to access new transition-metal chemistry and reactivity. As such, we show here that the bis(iminothienyl)methene L − reacts with metal salts to generate the neutral radical L • , the dicationic radical L •2+ or the dinuclear copper(I) complex Cu2I2(L • ) of a ligand-based iminothienyl radical. Scheme 1. Synthetic pathway to the monoanionic iminodithiophene KL and its redox reactions with metal salts (isolated yields in parentheses).Studies on the meso-C lithiation of dithiophenemethane compounds have found thermodynamic versus kinetic selectivity issues along with the formation of meso-C coupled products. [14] However, we find that deprotonation of HL with KH in THF ...