Photocatalytic functionalization of thin-layer membranes using a monomer truncation strategy.

We present the design and synthesis of two new organic polymer films making use of a liquid-liquid interfacial amine-acid chloride polymerization strategy. One of them was additionally functionalized in situ by the anchoring of N-phenyl-phenothiazine through a monomer truncation strategy, which endowed it with photocatalytic activity. This photoactive film displays interesting luminescence phenomena that were used for the oxidation of a variety of sulphides to their corresponding sulfoxides and reduction of aryl bromines.

Correction: Gligoric et al. IOTA-Based Distributed Ledger in the Mining Industry: Efficiency, Sustainability and Transparency. Sensors 2024, 24, 923.

In the original publication [...].

IOTA-Based Distributed Ledger in the Mining Industry: Efficiency, Sustainability and Transparency.

The paper presents a traceability framework founded upon a methodological approach specifically designed for the integration of the IOTA-based distributed ledger within the mining industry. This framework constitutes an initial stride towards the certification and labelling of sustainable material production. The efficacy of this methodology is subject to real-world evaluation within the framework of the European Commission funded project DIG_IT. Within the architectural framework, the integration of decentralized identifiers (DIDs) and the IOTA network are instrumental in effecting the encryption of data records, with associated hashes securely anchored on the explorer. Recorded environmental parameters, encompassing metrics such as pH level, turbidity, electrical conductivity, and emissions, serve as tangible evidence affirming their adherence to prevailing regulatory standards. The overarching system architecture encompasses a sophisticated Industrial Internet of Things platform (IIoTp), facilitating the seamless connection of data from a diverse array of sensors. End users, including governmental entities, mining managers, and the general public, stand to derive substantial benefits from tailored dashboards designed to facilitate the validation of data for emission compliance.

Intramolecular Hydrogen-Bond Activation: Strategies, Benefits, and Influence in Catalysis.

The activation of molecules through intramolecular hydrogen-bond formation to promote chemical reactions appears as a suitable strategy in organic synthesis, especially for the preparation of chiral compounds under metal and organocatalytic conditions. The use of this interaction has enabled reactivity enhancement of reagents, as well as stabilization of the chemical species and enantiocontrol of the processes.

Asymmetric synthesis of cyclic ß-amino carbonyl derivatives by a formal [3 + 2] photocycloaddition.

Herein, a visible-light mediated strategy unlocking a family of cyclic ß-amino carbonyl derivatives bearing three contiguous stereogenic centres is introduced. The overall reactivity relies on the performance of the substrate-catalyst complex to assist both the enantiocontrol and the photoredox tasks. This transformation led to an enantioselective [3 + 2] photocycloaddition between coordinated α,ß-unsaturated acyl imidazoles and cyclopropylamine derivatives.

Prime numbers and random walks in a square grid.

In recent years, computer simulations have played a fundamental role in unveiling some of the most intriguing features of prime numbers. In this paper, we define an algorithm for a deterministic walk through a two-dimensional grid, which we refer to as a prime walk. The walk is constructed from a sequence of steps dictated by and dependent on the sequence of the last digits of the primes. Despite the apparent randomness of this generating sequence, the resulting structure-in both two and three dimensions-created by the algorithm presents remarkable properties and regularities in its pattern, which we proceed to analyze in detail.

Asymmetric [2+2] photocycloaddition via charge transfer complex for the synthesis of tricyclic chiral ethers.

The asymmetric synthesis of chiral polycyclic ethers by an intramolecular [2+2] photocycloaddition is described. This process proceeded through a photocatalytically active iminium ion-based charge transfer (CT) complex under visible light irradiation. In this way a stereocontrolled [2+2] photocycloaddition is enabled leading to tricyclic products with good enantiomeric ratios.

Deformation-Controlled Design of Metallic Nanocomposites.

Achieving the theoretical strength of a metallic alloy material is a demanding task that usually requires utilizing one or more of the well-established routes: (1) Decreasing the grain size to stop or slow down the dislocation mobility, (2) adding external barriers to dislocation pathways, (3) altering the crystal structure, or (4) combining two of the previous discrete strategies, that is, implementing crystal seeds into an amorphous matrix. Each of the outlined methods has clear limitations; hence, further improvements are required. We present a unique approach that envelops all the different strength-building strategies together with a new phenomenon-phase transition. We simulated the plastic deformation of a Zr-Nb nanolayered alloy using molecular dynamics and ab initio methods and observed the transition of Zr from hexagonal close-packed to face-centered cubic and then to body-cenetered cubic during compression. The alloy, which was prepared by magnetron sputtering, exhibited near-theoretical hardness (10.8 GPa) and the predicted transition of the Zr structure was confirmed. Therefore, we have identified a new route for improving the hardness of metallic alloys.

Chromoselective access to Z- or E- allylated amines and heterocycles by a photocatalytic allylation reaction.

The most useful strategies for the alkylation of allylic systems are related to the Tsuji-Trost reaction or the use of different Lewis acids. Herein we report a photocatalytic approach for the allylation reaction of a variety of nucleophiles, such as heteroarenes, amines and alcohols. This method is compatible with a large variety of pyrroles and indoles, containing different substituents such as electron-withdrawing and electron-donating groups, unprotected nitrogen atoms and bromo derivatives. Moreover, this methodology enables the chromoselective synthesis of Z- or E-allylated compounds. While the use of UV-light irradiation has allowed the synthesis of the previously inaccessible Z-allylated products, E-isomers are prepared simply by changing both the light source to the visible region, and the catalytic system. Based on mechanistic and photochemical proofs, laser flash photolysis studies and DFT calculations, a rational mechanism is presented.

BODIPY as electron withdrawing group for the activation of double bonds in asymmetric cycloaddition reactions.

In this work we have found that a BODIPY can be used as an electron withdrawing group for the activation of double bonds in asymmetric catalysis. The synthesis of cyclohexyl derivatives containing a BODIPY unit can easily be achieved via trienamine catalysis. This allows a new different asymmetric synthesis of BODIPY derivatives and opens the door to future transformation of this useful fluorophore. In addition, the Quantum Chemistry calculations and mechanistic studies provide insights into the role of BODIPY as an EWG.

First principles simulation of damage to solvated nucleotides due to shock waves.

We present a first-principles molecular dynamics study of the effect of shock waves (SWs) propagating in a model biological medium. We find that the SW can cause chemical modifications through varied and complex mechanisms, in particular, phosphate-sugar and sugar-base bond breaks. In addition, the SW promotes the dissociation of water molecules, thus enhancing the ionic strength of the medium. Freed protons can hydrolyze base and sugar rings previously opened by the shock. However, many of these events are only temporary, and bonds reform rapidly. Irreversible damage is observed for pressures above 15-20 GPa. These results are important to gain a better understanding of the microscopic damage mechanisms underlying cosmic-ray irradiation in space and ion-beam cancer therapy.

Development and Application of Asymmetric Organocatalytic Mukaiyama and Vinylogous Mukaiyama-Type Reactions.

Organocatalysis is a growing area that is benefiting from advances in many fields. Its implementation has begun in areas such as supramolecular chemistry, organic chemistry and natural product synthesis. While a considerable number of important publications in the field of organocatalytic Mukaiyama-type additions have been reported, they are yet to be fully covered in a review. Therefore, we would like to highlight the applications of various kinds of organocatalysts in Mukaiyama-type reactions, while also including the vinylogous Mukaiyama variation. Herein we describe and discuss the development and current state of the art of the organocatalytic Mukaiyama reaction, vinylogous Mukaiyama and related reactions.

Intramolecular hydrogen-bond activation for the addition of nucleophilic imines: 2-hydroxybenzophenone as a chemical auxiliary.

The addition of nucleophilic imines, using 2-hydroxybenzophenone as a chemical auxiliary, is presented. An intramolecular six-membered ring via hydrogen bonding that enhances the reactivity and selectivity is the key of this strategy, which is supported by DFT calculations and experimental trials.

Intramolecular Hydrogen Bond Activation: Thiourea-Organocatalyzed Enantioselective 1,3-Dipolar Cycloaddition of Salicylaldehyde-Derived Azomethine Ylides with Nitroalkenes.

An organocatalytic strategy for the synthesis of tetrasubstituted pyrrolidines with monoactivated azomethine ylides in high enantiomeric excess and excellent exo/endo selectivity is presented. The key to success is the intramolecular activation via hydrogen bonding through an o-hydroxy group, which allows the dipolar cycloaddition to take place in the presence of azomethine ylides bearing only one activating group. The intramolecular hydrogen bond in the azomethine ylide and the intermolecular hydrogen bond with the catalyst have been demonstrated by DFT calculations and mechanistic proofs to be crucial for the reaction to proceed.

2-Hydroxybenzophenone as a Chemical Auxiliary for the Activation of Ketiminoesters for Highly Enantioselective Addition to Nitroalkenes under Bifunctional Catalysis.

An organocatalytic system is presented for the Michael addition of monoactivated glycine ketimine ylides with a bifunctional catalyst. The ketimine bears an ortho hydroxy group, which increases the acidity of the methylene hydrogen atoms and enhances the reactivity, thus allowing the synthesis of a large variety of α,γ-diamino acid derivatives with excellent stereoselectivity.

A General Asymmetric Formal Synthesis of Aza-Baylis-Hillman Type Products under Bifunctional Catalysis.

A new organocatalytic strategy for the synthesis of enantioenriched aza-Baylis-Hillman type products via a frustrated vinylogous reaction is presented. This process proceeds under mild conditions with good yields, completed Z/E selectivity and excellent enantioselectivities. Moreover, easy derivatizations of the final products led to important building blocks of organic synthesis such as 1,3-aminoalcohols and Lewis base catalysts.

Thiol-ene/oxidation tandem reaction under visible light photocatalysis: synthesis of alkyl sulfoxides.

The photocatalyzed synthesis of sulfoxides from alkenes and thiols has been carried out using Eosin Y. This is a metal-free method which uses a low catalyst loading, atmospheric oxygen as the oxidant, and visible light conditions (green light). A mechanism has been proposed that is consistent with the experimental results.

"Anti-Michael addition" of Grignard reagents to sulfonylacetylenes: synthesis of alkynes.

In this work, the addition of Grignard reagents to arylsulfonylacetylenes, which undergoes an "anti-Michael addition", resulting in their alkynylation under very mild conditions is described. The simplicity of the experimental procedure and the functional group tolerance are the main features of this methodology. This is an important advantage over the use of organolithium at -78 °C that we previously reported. Moreover, the synthesis of diynes and other examples showing functional group tolerance in this anti-Michael reaction is also presented.

Asymmetric Synthesis of 1,2-Diamines bearing Tetrasubstituted Centers from Nonstabilized Azomethine Ylides and N-Sulfinylketimines under Brønsted Acid Catalysis.

The first asymmetric cycloaddition of nonstabilized azomethine ylide and N-sulfinylimines is presented. In reactions with aryl-alkyl and heteroaryl-alkyl ketimines, excellent diastereoselectivities and good yields are obtained in all cases, regardless of the electronic character of the substituents at the aromatic rings. Moreover, the cycloadducts obtained can easily be deprotected in acid media, giving access to free 1,2-diamines which are prevalent in many natural and pharmaceutical products.

Control of the dual reactivity (iminium-dienamine) of ß-arylmethyl α,ß-unsaturated aldehydes in organocatalytic 1,3-dipolar cycloadditions with N-benzoyl C,N-cyclic azomethine imines.

1,3-Dipolar cycloadditions of C,N-cyclic azomethine imines with α,ß-unsaturated aldehydes can be performed with complete control of the regio-, exo-, and enantioselectivity under aminocatalytic conditions. The so far never studied competence of the iminium-dienamine reactivity inherent to ß-alkyl α,ß-unsaturated aldehydes was studied, which was possible by allowing achievement of complete control of the chemoselectivity in reactions of the ß-arylmethyl derivatives with azomethine imines by using different additives and organocatalysts, whose role has been rationalized by DFT calculations and chemical proofs. Thus, it has been possible to selectively obtain the pyrazolidines resulting from both the attack to the C2-C3 (via iminium) and the C3-C4 (via dienamine) bonds at the starting enals, which can be used as precursors of interesting tetrahydroisoquinolinic compounds.