Molecular entanglement can strongly increase basicity.

Brønsted basicity is a fundamental chemical property featured by several kinds of inorganic and organic compounds. In this Review, we treat a particularly high basicity resulting from the mechanical entanglement involving two or more molecular subunits in catenanes and rotaxanes. Such entanglement allows a number of basic sites to be in close proximity with each other, highly increasing the proton affinity in comparison with the corresponding, non-entangled counterparts up to obtain superbases, properly defined as mechanically interlocked superbases.

Kinetic Trapping of an Out-of-Equilibrium Dynamic Library of Imines by Changing Solvent.

A well-behaved dynamic library composed of two imines and corresponding amines was subjected to the action of an activated carboxylic acid (ACA), whose decarboxylation is known to be base promoted, in different solvents, namely CDCl, CDCN, and mixtures of them. Two non-equilibrium systems are consequently obtained: i) a dissipative (CDCl) and ii) an out-of-equilibrium (CDCN) dynamic library whose composition goes back to equilibrium after a given time. In the former case, the library is fully coupled with the decarboxylation of the ACA, while in the latter, an energy ratchet operates.

Signal Transduction Allows Temporal Control of the Potential of a Concentration Cell Driven by the Decarboxylation of an Activated Carboxylic Acid.

The use of Activated Carboxylic Acids (ACAs) allows the time-controlled operation of dissipative chemical systems based on the acid-base reaction by providing both the stimulus that temporarily drives a physicochemical change and, subsequently, the counter-stimulus with a single reagent addition. However, their application is inherently limited to acid-sensitive systems. To overcome this limitation, we herein develop a straightforward device for the transduction of the acid-base stimuli delivered by an ACA into a voltage signal that, in turn, is used to control voltage-sensitive circuits that are not pH-responsive by themselves.

A Doubly Dissipative System Driven by Chemical and Radiative Stimuli.

The operation of a dissipative network composed of two or three different crown-ether receptors and an alkali metal cation can be temporally driven by the use (combined or not) of two orthogonal stimuli of a different nature. More specifically, irradiation with light at a proper wavelength and/or addition of an activated carboxylic acid, are used to modulate the binding capability of the above crown-ethers towards the metal ion, allowing to control over time the occupancy of the metal cation in the crown-ether moiety of a given ligand. Thus, application of either or both of the stimuli to an initially equilibrated system, where the metal cation is distributed among the crown-ether receptors depending on the different affinities, causes a programmable change in the receptor occupancies.

Controlling the Conformation of 2-Dimethylaminobiphenyls by Transient Intramolecular Hydrogen Bonding.

Temporal control of molecular motions is receiving increasing attention because it is central to the development of molecular switches and motors and nanoscopic materials with life-like properties. Inspired by previous studies, here, we report that acid can be used to temporally control the conformational freedom around the C-C bond connecting the two aromatic rings of the ditopic bases and . Consistent with NMR measurements and DFT calculations, before fuel addition, the conformational motion of the two aromatic rings of both and mainly consists of a large amplitude torsional oscillation spanning about 260° and passing for the conformation (the two nitrogen atoms at opposite sides).

Titania as Buffer Layer for Cd-Free Kesterite Solar Cells.

Pure sulfide kesterite (CuZnSnS) is one of the most promising emerging photovoltaic technologies thanks to its excellent absorption coefficient, cost-effectiveness, and environmental sustainability. However, record efficiencies are not exceeding 11% due to several issues, such as absorber defects or a nonoptimal band alignment with the toxic but conventionally used CdS buffer layer. To get rid of it, several efforts have been made in the past few years.

Dissipative Dynamic Covalent Chemistry (DDCvC) Based on the Transimination Reaction.

This work reports that the composition of a dynamic library (DL) of interconverting imines can be controlled over time in a dissipative fashion by the addition of an activated carboxylic acid used as a chemical fuel. When the fuel is added to the DL, which is initially under thermodynamic equilibrium, the composition of the mixture dramatically changes and a new, dissipative (out of equilibrium) state is reached that persists until fuel exhaustion. Thus, a transient dissipative dynamic library (DDL) is generated that, eventually, reverts back to the initial DL when the fuel is consumed, closing a DL→DDL→DL cycle.

Time-programmable pH: decarboxylation of nitroacetic acid allows the time-controlled rising of pH to a definite value.

In this report it is shown that nitroacetic acid (ONCHCOH) can be conveniently used to control the pH of a water solution over time. Time-programmable sequences of the kind pH-pH-pH can be achieved, where both the extent of the initial pH jump (pH-pH) and the time required for the subsequent pH rising (pH-pH) can be predictably controlled by a judicious choice of the absolute and relative concentrations of the reagents (acid and NaOH). Successive pH-pH-pH sequences can be obtained by subsequent additions of acid .

Changing Pattern of Femoral Deformity During Growth in Polyostotic Fibrous Dysplasia of the Bone: An Analysis of 46 Cases.

Background: In polyostotic fibrous dysplasia (PFD) affecting the femur, 6 types of stable femoral deformities have been identified, ranging from the mild type 1 to the most severe type 6. The purpose of our study was to identify the type of deformity present at diagnosis in children with PFD affecting the femur, and to investigate possible changes in the original type with growth.

Methods: Twenty-seven children affected by either PFD or McCune-Albright syndrome, with 46 affected femurs, were consecutively observed from 1994 to 2010.

Two-stage surgical treatment of complex femoral deformities with severe coxa vara in polyostotic fibrous dysplasia.

Background: In patients with polyostotic fibrous dysplasia with extensive femoral involvement, severe coxa vara may cause complex femoral deformities that are difficult to treat with a single-stage surgical procedure. We evaluated the results of treatment of such patients with a two-stage procedure.

Methods: Eleven patients with polyostotic fibrous dysplasia and severe coxa vara (including one who required bilateral treatment and one who required repeat treatment) were treated surgically at a mean age of fourteen years and four months.

Surface-based haemangioma of the tibia: a case report.

We present in this paper a case of surface-based haemangioma of the tibia in a 34-year-old patient which had been misdiagnosed as periostitis. X-ray examination demonstrated a periosteal reaction, confirmed by a MRI showing a soft tissue mass adjacent to bone. We performed an incisional biopsy and made a diagnosis of haemangioma only after examining the histological results.