Dihydrogen is one of the sustainable energy vectors envisioned for the future. However, the rapidly reversible and secure storage of large quantities of hydrogen is still a technological and scientific challenge. In this context, this review proposes a recent state-of-the-art on H 2 production capacities from the dehydrogenation reaction of ammonia borane (and selected related amine-boranes) as a safer solid-source of H 2 by hydrolysis (or solvolysis), according to the different developed nanoparticle-based catalysts. The review groups the results according to the transition metals constituting the catalyst according a special view to current cost/availability consideration. This includes the noble metals Rh, Pd, Pt, Ru, Ag, as well as transition metals such as Co, Ni, Cu, and Fe. For each element, the monometallic and polymetallic structures, isolated or supported, are presented and the performances described in terms of TOF and recyclability. The structure-property links are highlighted whenever possible. It appears from all these works that the mastery of the preparation of catalysts remains a crucial point; not only in terms of process but also in terms of mastery of the electronic structures of the elaborated nanomaterials. A particular effort of the scientific community remains to be made in this multidisciplinary field with major societal stakes.

With the view to enhancing the unique coordinating ability of the known phenyl-tetrakis(diisopropylamino)dicyclopropeniophosphine (Ph-DCP), replacement of the phenyl substituent by a tert-butyl substituent was envisaged. Both α-dicationic R-DCP phosphines, with R = Ph and Bu, were prepared in 54%-55% yield by substitution of RPCl with two equivalents of bis(diisopropylamino)-dicyclopropenylidene (BAC) and metathesis with NaBF. This method is implicitly consistent with the representation of R-DCPs as BAC-phosphenium adducts. The R-DCP salts were found to coordinate hard and soft Lewis acids such as a promoted oxygen atom (in the singlet spin state) in the corresponding R-DCP oxides, and electron-rich transition-metal centers in η-R-DCP complexes with AuCl, PtCl, or PdCl, respectively. Coordination of Ph-DCP with PdCl, which is a more electron-deficient Pd(II) center, leads to pentachlorinated dinuclear complexes [(Ph-DCP)PdCl]Cl, where the dicoordinate Cl bridge screens the repelling pairs of positive charges from each other. The same behavior is inferred for the Bu-DCP ligand, from which addition of an excess of (MeCN)PdCl was found to trigger a heterolytic cleavage of the DCP-Bu bond, releasing Bu and a dicationic phosphide, DCP: the latter is evidenced as a ligand in a tetranuclear complex ion [(μ-DCP)PdCl], which, upon HCl treatment, dissociates to a doubly zwitterionic dipalladate complex. All the complexes were isolated in 82%-97% yield, and five of them were characterized by X-ray crystallography.

We report a general route for synthesizing ortho-substituted unsymmetrical biphenyl and polyaromatic s-aryltetrazines. These compounds are inaccessible by classical Pinner hydrazine condensation or by the current s-aryltetrazine aromatic core functionalization methods described up to now. We exploited multiple versatile N-directed palladium C–H activation/halogenation of s-aryltetrazine to form C–X bonds (X = I, Br, Cl, F), which collectively produced polyhalogenated unsymmetrical building blocks. We achieved a sequence of selective C–H halogenation reactions in a specific order to produce reactive aryl halides. Polyhalogenated s-aryltetrazines can then be used for controlled cross-coupling reactions toward ortho-substituted polyaromatic s-aryltetrazines. In general, this C–H functionalization route gives access to a large number of variously halogenated building blocks practical for further synthetic implementation of tetrazines (arylation, cycloaddition, etc.). Herein, we exemplified their potential by using halogen-selective Suzuki–Miyaura reactions for divergent construction of novel biphenyl s-tetrazines. Therefore, we deliver original poly­(hetero)­aromatic tetrazine structures, such as new typically “Z-shaped” and “T-shaped” species. We examined by DFT calculation the origin of the remarkable regioselectivity in some C–H concurrent halogenation reactions. Computations focused at free enthalpy profiles for C–H activation of aryltetrazines to form the intermediate palladacycles by CMD process. We showed that the presence of halogen substituents on aryl groups before further halogenation increases the activation barrier to form the determining C–H activation intermediate palladacycle. XRD studies of functionalized tetrazines evidenced planarity ruptures in the mutual arrangement of aromatic cycles. Finally, this methodology allowed us to deliver a unique tetrahalogenated s‑aryltetrazine holding not less than four different halogens arranged in ortho-aryl positions.

Click chemistry at a tetrazine core is useful for bioorthogonal labeling and crosslinking. Introduced here are two new classes of doubly clickable s‐aryl tetrazines synthesized by Cu‐catalyzed cross‐coupling. Homocoupling of o‐brominated s‐aryl tetrazines leads to bis(tetrazine)s structurally characterized by tetrazine cores arranged face‐to‐face. [N]8 π‐stacking interactions are essential to the conformation. Upon inverse electron demand Diels–Alder (iEDDA) cycloaddition, the bis(tetrazine)s produce a unique staple structure. The o‐azidation of s‐aryl tetrazines introduces a second proximal intermolecular clickable function that leads to double click chemistry opportunities. The stepwise introduction of fluorophores and then iEDDA cycloaddition, including bioconjugation to antibodies, was achieved on this class of tetrazines. This method extends to (thio)etherification, phosphination, trifluoromethylation and the introduction of various bioactive nitrogen‐based heterocycles.

No abstract

Diamondoids, sp3‐hybridized nanometer‐sized diamond‐like hydrocarbons (nanodiamonds), difunctionalized with hydroxy and primary phosphine oxide groups, enable the assembly of the first sp3‐C‐based chemical sensors by vapor deposition. Both pristine nanodiamonds and palladium nanolayered composites can be used to detect toxic NO2 and NH3 gases. This carbon‐based gas sensor technology allows reversible NO2 detection down to 50 ppb and NH3 detection at 25–100 ppm concentration with fast response and recovery processes at 100 °C. Reversible gas adsorption and detection is compatible with 50 % humidity conditions. Semiconducting p‐type sensing properties are achieved from devices based on primary phosphine–diamantanol, in which high specific area (ca. 140 m2 g−1) and channel nanoporosity derive from H‐bonding.

Diamondoids, sp3‐hybridized nanometer‐sized diamond‐like hydrocarbons (nanodiamonds), difunctionalized with hydroxy and primary phosphine oxide groups, enable the assembly of the first sp3‐C‐based chemical sensors by vapor deposition. Both pristine nanodiamonds and palladium nanolayered composites can be used to detect toxic NO2 and NH3 gases. This carbon‐based gas sensor technology allows reversible NO2 detection down to 50 ppb and NH3 detection at 25–100 ppm concentration with fast response and recovery processes at 100 °C. Reversible gas adsorption and detection is compatible with 50 % humidity conditions. Semiconducting p‐type sensing properties are achieved from devices based on primary phosphine–diamantanol, in which high specific area (ca. 140 m2 g−1) and channel nanoporosity derive from H‐bonding.

An a-vinylation of enolizable ketones has been developed by using b-bromostyrenes and a KOtBu/NMP system. β,γ-Unsaturated ketones of E configuration were obtained in excellent yield and selectivity. Further synthetic possibilities are highlighted by one-pot functionalization via trapping of intermediate dienolates with alkyl, allyl, benzyl, and propargyl halides to generate quaternary centers. The reported transformation is believed to proceed via phenylacetylene and propargylic alcohol intermediates. Regio-and Steroselective 27 Examples, up to 95% yield