Electrocatalytic Micelle-Driven Hydrodefluorination for Accessing Unprotected Monofluorinated Indoles.

Toxic organic solvents and electrolytes, traditionally indispensable for electro-organic synthesis, are now being reconsidered. In developing more sustainable electro-organic synthesis, we've harnessed the aqueous micelles as solvents and electrolyte-like structures when deformed under an electric field. The technology is showcased in synthetically highly valued hydrodefluorination reactions of difluorinated indoles.

Simultaneous Cycloadditions in the Solid State via Supramolecular Assembly.

Chemical reactions conducted in the solid phase (specifically, crystalline) are much less numerous than solution reactions, primarily due to reduced motion, flexibility, and reactivity. The main advantage of crystalline-state transformations is that reactant molecules can be designed to self-assemble into specific spatial arrangements, often leading to high control over product regiochemistry and/or stereochemistry. In crystalline-phase transformations, typically only one type of reaction occurs, and a sacrificial template molecule is frequently used to facilitate self-assembly, similar to a catalyst or enzyme.

Hierarchical 2D honeycomb-like network from barium-seamed nanocapsules.

We report on a two-dimensional hexagonal "honeycomb" network comprising barium-seamed metal-organic nanocapsules involving a hexameric assembly of pyrogallol[4]arene ligands. The incorporated barium ions act as spacers to generate a solvent-accessible void, hierarchical self-assembly having an individual void volume near 13 000 Å. This work illustrates the surprising chemistry that remains to be discovered by integrating large or classically non-reactive metal ions within supramolecular assemblies, networks, and organic nanocapsules.

Predicting photoactivity in dithienylethene crystalline solids.

This commentary discusses the design of stimuli-responsive materials, specifically, light-responsive dithienylethene-based compounds. Recent progress in predicting photoactivity using a combination of theory and crystal structure landscape experiments is highlighted.

Ligand-Free Ultrasmall Recyclable Iridium(0) Nanoparticles for Regioselective Aromatic Hydrogenation of Phosphine Oxide Scaffolds: An Easy Access to New Phosphine Ligands.

Herein, we developed the recyclable ligand-free iridium (Ir)-hydride based Ir nanoparticles (NPs) for the first regioselective partial hydrogenation of P -substituted naphthalenes. Both the isolated and in situ generated NPs are catalytically active. A control nuclear magnetic resonance (NMR) study revealed the presence of metal-surface-bound hydrides, most likely formed from Ir species.

Hydrogen-Atom Electronic Basis Sets for Multicomponent Quantum Chemistry.

Multicomponent methods are a conceptually simple way to include nuclear quantum effects into quantum chemistry calculations. In multicomponent methods, the electronic molecular orbitals are described using the linear combination of atomic orbitals approximation. This requires the selection of a one-particle electronic basis set which, in practice, is commonly a correlation-consistent basis set.

Self-Assembly of a Semiconductive and Photoactive Heterobimetallic Metal-Organic Capsule.

We report the synthesis of a novel metal-organic capsule constructed from six pyrogallol[4]arene macrocycles, which are switched together by 16 Fe and 16 Co ions. This supramolecular structure is the first instance of a spheroidal heterometallic nanocage assembled through a one-step metal-ligand coordination approach. This new assembly also demonstrates an important proof of concept through the formation of multiple heterometallic metal-metal interactions within the capsule framework.

An Indium-Seamed Hexameric Metal-Organic Cage as an Example of a Hexameric Pyrogallol[4]arene Capsule Conjoined Exclusively by Trivalent Metal Ions.

A hexameric metal-organic nanocapsule is assembled from pyrogallol[4]arene units, which are stitched together with indium ions. This indium-seamed capsule is the first instance of a M L type hexameric coordination cage held together exclusively by trivalent metal ions. Explicitly, unlike previously reported pyrogallol[4]arene-based metal-seamed capsules, the current In seamed capsule is entirely supported by O→In coordinate bonds.

Synthesis and evaluation of Re/Tc(I) complexes bearing a somatostatin receptor-targeting antagonist and labeled via a novel [N,S,O] clickable bifunctional chelating agent.

The somatostatin receptor subtype 2 (SSTR2) is often highly expressed on neuroendocrine tumors (NETs), making it a popular in vivo target for diagnostic and therapeutic approaches aimed toward management of NETs. In this work, an antagonist peptide (sst-ANT) with high affinity for SSTR2 was modified at the N-terminus with a novel [N,S,O] bifunctional chelator (2) designed for tridentate chelation of rhenium(I) and technetium(I) tricarbonyl cores, [Re(CO)] and [Tc][Tc(CO)]. The chelator-peptide conjugation was performed via a Cu(I)-assisted click reaction of the alkyne-bearing chelator (2) with an azide-functionalized sst-ANT peptide (3), to yield NSO-sst-ANT (4).

Mixed transitions in the UV photodissociation of propargyl chloride revealed by slice imaging and multireference ab initio calculations.

Resonance-enhanced multiphoton ionization (REMPI) and DC slice imaging were used to detect photoproducts Cl (2P3/2), spin-orbit excited Cl* (2P1/2), and C3H3 in the photodissociation of propargyl chloride at 212 and 236 nm. Cl and Cl* translational energy distributions peak at high recoil energy, suggesting impulsive energy release in the C-Cl coordinate. Near 236 nm, photofragment angular distributions show rapidly changing anisotropy across the main peak for both Cl and Cl*, indicating excitations arising from in-plane or out-of-plane π systems.

A Multi-Component Sensor System for Detection of Amphiphilic Compounds.

Many biologically important compounds are amphiphilic in character. Glycolipids, for example, represent a biologically important class of amphiphiles. Receptors and sensors for such compounds must also be amphiphilic making them a challenge to prepare.

Ionic liquid inspired alkalinochromic salts based on Reichardt's dyes for the solution phase and vapochromic detection of amines.

Chromogenic salts based on the negatively solvatochromic pyridinium N-phenolate betaines 2,6-diphenyl-4-(2,4,6-triphenyl-N-pyridino)-phenolate (Reichardt's dye 30) and 2,6-dichloro-4-(2,4,6-triphenyl-N-pyridino)-phenolate (Reichardt's dye 33) proved to be promising probes for the colorimetric detection of bases, including hydroxide ion, ammonia, and aliphatic amines. Specifically, the protonated halide forms of these two dyes were ion exchanged to generate lipophilic bis(trifluoromethylsulfonyl)imide derivatives, denoted [E(30)][TfN] and [E(33)][TfN], respectively. When dissolved in 95 vol% EtOH, these essentially colorless solutions displayed dramatic "alkalinochromic" color-on switching due to phenolic deprotonation to generate the zwitterionic form of the dyes with their characteristic charge-transfer absorption.

A ML metal-organic nanocapsule with open windows using mixed macrocycles.

We present here the preparation of a ML hexameric metal-organic nanocapsule using a pyrogallol[3]resorcin[1]arene mixed macrocycle. The introduction of resorcinol moieties within the assembly leads to the formation of two open windows. This study demonstrates that introducing defects into the existing structure of nanocapsules may act as an effective method to tailor the composition and geometry, and introduce new properties.

Formation of Water Channels in the Crystalline Hydrates of Macrocyclic Compounds.

Crystalline hydrates of macrocyclic compounds such as pyroagllol[4]arenes (PgCs) and resorcin[4]arenes (RsCs) are rare owing to their lower water solubility. Functionalization of these macrocyclic compounds is an affordable way to enhance water solubility. However, functionalization also encounters the formation of multiple conformers and subsequent difficulty in purification of the product.

Isomer-specific detection in the UV photodissociation of the propargyl radical by chirped-pulse mm-wave spectroscopy in a pulsed quasi-uniform flow.

Isomer-specific detection and product branching fractions in the UV photodissociation of the propargyl radical is achieved through the use of chirped-pulse Fourier-transform mm-wave spectroscopy in a pulsed quasi-uniform flow (CPUF). Propargyl radicals are produced in the 193 nm photodissociation of 1,2-butadiene. Absorption of a second photon leads to H atom elimination giving three possible CH isomers: singlets cyclopropenylidene (c-CH) and propadienylidene (l-CH), and triplet propargylene (HCCCH).

Novel magnesium-seamed organic nanocapsules with hierarchical structural complexity.

Enhancing hierarchical structural complexities of metal-organic nanocapsules is an effective way of introducing new functions and properties. Herein, we present the synthesis of novel magnesium-seamed C-alkylpyrogallol[4]arene nanocapsules with hierarchical structural complexity via both exterior and endohedral functionalization. The exterior functionalization is realized by using a variety of covalently modified pyrogallol[4]arene ligands, while the endohedral functionalization is achieved via coordination-driven self-assembly.

Self-assembly of ML metal-organic nanocapsules using mixed macrocycles.

The solvothermal synthesis of two ML metal-organic nanocapsules from C-alkyl pyrogallol[3]resorcin[1]arene is reported. Using mixed macrocycles as building blocks shows great potential in the discovery of new metal-organic nanocapsules with novel properties.

Preparation of Magnesium-Seamed C-Alkylpyrogallol[4]arene Nanocapsules with Varying Chain Lengths.

Novel supramolecular nanocapsules based on metal-directed assembly have captured tremendous interest due to their applications in fields such as catalysis, selective gas adsorption, and biomedicine. Functionalization of metal-organic nanocapsules (MONCs) by using organic ligands with different pendant groups affords more complexity to the structure and may lead to novel properties. In this work, we report the solvothermal synthesis of a group of magnesium-based MONCs using C-alkylpyrogallol[4]arenes with varying alkyl chain lengths.

Self-assembly of magnesium-seamed hexameric pyrogallol[4]arene nanocapsules.

The solvothermal synthesis of a metal-seamed hexameric nanocapsule from pyrogallol[4]arenes and magnesium is reported. The unique non-toxic and biocompatible nature of divalent magnesium cations in addition to the large inherent cavities make these nanocapsules promising for potential application in biomedicine. In addition, we show that these nanocapsules can form cocrystals with pyridine molecules through hydrogen bonding, which sheds light to cocrystallization of supramolecular nanocapsules with small pharmaceutics.

Process Development for Separation of Conformers from Derivatives of Resorcin[4]arenes and Pyrogallol[4]arenes.

Macrocyclic compounds, such as resorcin[4]arenes and pyrogallol[4]arenes, have proven to be useful building blocks in the construction of supramolecular organic frameworks (SOFs) because of their unique bowl-like shape and ability to interact through variety of intermolecular interactions. Herein, we report the synthesis and crystal structures of two functionalized resorcin[4]arenes and pyroagllol[4]arenes, 4-hydroxyphenylresorcin[4]arenes, and 4-hydroxyphenylpyrogallol[4]arenes. These phenyl-functionalized macrocycles usually have different conformers, such as cone, boat, chair, saddle, and diamond.

Selective CO2 Adsorption in a Supramolecular Organic Framework.

Considering the rapidly rising CO2 level, there is a constant need for versatile materials which can selectively adsorb CO2 at low cost. The quest for efficient sorptive materials is still on since the practical applications of conventional porous materials possess certain limitations. In that context, we designed, synthesized, and characterized two novel supramolecular organic frameworks based on C-pentylpyrogallol[4]arene (PgC5 ) with spacer molecules, such as 4,4'-bipyridine (bpy).

Tunable Molecular Logic Gates Designed for Imaging Released Neurotransmitters.

Tunable dual-analyte fluorescent molecular logic gates (ExoSensors) were designed for the purpose of imaging select vesicular primary-amine neurotransmitters that are released from secretory vesicles upon exocytosis. ExoSensors are based on the coumarin-3-aldehyde scaffold and rely on both neurotransmitter binding and the change in environmental pH associated with exocytosis to afford a unique turn-on fluorescence output. A pH-functionality was directly integrated into the fluorophore π-system of the scaffold, thereby allowing for an enhanced fluorescence output upon the release of labeled neurotransmitters.

New synthesis of α'-hydroxydienones.

Herein, attempted oxidation of selected allenols with PCC affording α'-hydroxydienones rather than simple oxidation products is described. The formation of the products observed is rationalized via a series of sigmatropic shifts, followed by hydrolysis.