Lone-Pair-p Bond Strength Unveiled by a Combined Experimental and Computational Study.

A series of naphthalene-diimide (NDI) and perylene-diimide (PDI) connected bis-N-heterocyclic carbene complexes of iridium (III) have been prepared and fully characterized. The analysis of their NMR spectroscopic features, together their molecular structures show that these species display lone pair-p interactions between the chloride ligands of the Ir(III) complex and the heterocycles of the NDI/PDI moieties. The detection of this type of interaction in solution is due to the formation of two atropisomers, which are formed as a result of the restricted rotation about the Ir-Ccarbene bond imposed by the (Cl)lp…p interaction. Variable temperature 1H NMR analysis allowed to determine the strength of this non-covalent interaction, which lies between DH = 6.6-10 kcal/mol. The computational studies performed fully support the experimental findings. Our study demonstrates that this type of lp…p interaction is comparable to strong hydrogen bonding.

Five-year results of atropine 0.01% efficacy in the myopia control in a European population.

AIMS: To evaluate the efficacy and safety of 0.01% atropine eye-drops in controlling myopia progression over 5 years. METHODS: Experimental, analytical, prospective, randomised and longitudinal study, in 361 right eyes from 361 children randomised into the control group (177 eyes without treatment) and treatment group (184 eyes with 0.01% atropine eye-drops). Children assigned to the treatment group used 0.01% atropine once a day every night and the control group's children did not use any treatment or placebo. All the subjects completed an eye examination every 6 months for the 5 years of follow-up. The examination included subjective and objective refraction with cycloplegia, axial length (AL), keratometry and anterior chamber depth (ACD) to evaluate the efficacy of the treatment. It also included the anterior and posterior pole examination to evaluate the safety of the treatment. RESULTS: The SE increased -0.63±0.42D in children after 5 years of treatment with 0.01% atropine, while in the control group the increase was -0.92±0.56D. AL increased 0.26±0.28 mm in the treatment group compared with 0.49±0.34 mm in the control group. Atropine 0.01% showed an efficacy of 31.5% and 46.9% in the control of the SE and AL increase, respectively. ACD and keratometry did not have significant changes between groups. CONCLUSIONS: Atropine 0.01% is effective in slowing myopia progression in a European population. There were no side effects after 5 years of 0.01% atropine.

The role of crystal facets and disorder on photo-electrosynthesis.

Photoelectrochemistry has the potential to play a crucial role in the storage of solar energy and the realisation of a circular economy. From a chemical viewpoint, achieving high conversion efficiencies requires subtle control of the catalyst surface and its interaction with the electrolyte. Traditionally, such control has been hard to achieve in the complex multinary oxides used in PEC devices and consequently the mechanisms by which surface exposed facets influence light-driven catalysts are poorly understood. Yet, this understanding is critical to further improve conversion yields and fine-tune reaction selectivities. Here, we review the impact that crystal facets and disorder have on photoelectrochemical reactivity. In particular, we discuss how the crystal orientation influences the energetics of the surface, the existence of defects and the transport of reactive charges, ultimately dictating the PEC activity. Moreover, we evaluate how facet stability dictates the tendency of the solid to undergo reconstructions during catalytic processes and highlight the experimental and computational challenges that must be overcome to characterise the role of the exposed facets and disorder in catalytic performance.

Redox-Switchable Cycloisomerization of Alkynoic Acids with Napthalenediimide-Derived N-Heterocyclic Carbene Complexes.

Two naphthalene-diimide (NDI) bis-imidazolium salts have been used as N-heterocyclic carbene (NHC) precursors for the preparation of NDI-functionalized complexes of rhodium and iridium of general formula [MCl(NDI-NHC)(COD)] (M=Rh, Ir; NDI-NHC=NDI-functionalized NHC ligand). Comparison of the IR spectra of the complexes [IrCl(NDI-NHC)(CO)2 ] and their related one- and two-electron reduced forms, reveal that each one-electron reduction produces a decrease of the average ν(CO) of 9-10 cm-1 , indicating a significant enhancement of the electron-richness of the metal. The [MCl(NDI-NHC)(COD)] complexes were tested in the catalytic cycloisomerization of alkynoic acids. The one-electron reduced forms showed greatly enhanced activities. For the cyclization of 5-hexynoic acid, the two-electron reduction of the ligand produced further enhancement of the catalytic activity, therefore showing that the catalyst can switch between three redox species with three distinct catalytic activities.

Template-Controlled Synthesis of Polyimidazolium Salts by Multiple [2+2] Cycloaddition Reactions.

The tetrakisimidazolium salt H4 -2(Br)4 , featuring a central benzene linker and 1,2,4,5-(nBu-imidazolium-Ph-CH=CH-) substituents reacts with Ag2 O in the presence of AgBF4 to yield the tetranuclear, oktakis-NHC assembly [3](BF4 )4 . Cation [3]4+ features four pairs of olefins from the two tetrakis-NHC ligands perfectly arranged for a subsequent [2+2] cycloaddition. Irradiation of [3](BF4 )4 with a high pressure Hg lamp connects the two tetra-NHC ligands through four cyclobutane linkers to give compound [4](BF4 )4 . Removal of the template metals yields the novel oktakisimidazolium salt H8 -5(BF4 )8 . The tetrakisimidazolium salt H4 -2(BF4 )4 and the oktakisimidazolium salt H8 -5(BF4 )8 have been used as multivalent anion receptors and their anion binding properties towards six different anions have been compared.