Highly efficient bifunctional oxygen reduction/evolution activity of a non-precious nanocomposite derived from a tetrazine-COF.

We report a novel s-tetrazine based covalent organic framework (TZA-COF) and its hybrid nanocomposites with reduced graphene oxide (TZA-COF-rGO) and Co metal to illustrate novel structure-activity relationships in this class of compounds for electrocatalytic oxygen reduction reaction (ORR). The Co-impregnated hybrid composites (TZA-COF-rGO-Co) were further annealed to yield Co-encapsulated nitrogen doped graphitic carbon (Co@NC-600), which exhibited excellent ORR activity comparable to that of the state-of-the art Pt/C in terms of onset potential, E1/2 (half-wave potential), 4e- reduction selectivity and methanol tolerance. Sequential mechanistic analyses of activity enhancement and electron transfer pathways for the ORR, at different stages of controlled catalyst engineering, elucidated the crucial role of active sites and overall catalyst nature in tuning the ORR mechanism.

Quadruple bonding of bare group-13 atoms in transition metal complexes.

Density functional theory calculations at the M06-D3/def2-TZVPPD level of the group-13 anion complexes EFe(CO)3- (E = B-Tl) and the isoelectronic neutral and charged boron adducts BTM(CO)3q (TMq = Fe-, Ru-, Os-, Co, Rh, Ir, Ni+, Pd+, Pt+) give tetrahedral (C3v) geometries in the 1A1 electronic ground state as equilibrium structures. The analysis of the bonding situation with the energy decomposition analysis in combination with natural orbital for chemical valence method suggests that the E-TM(CO)3q bonds possess four bonding components: (a) one strong electron-sharing σ bond E-TM(CO)3q; (b) two π backdonations E⇇TM(CO)3q and (c) one weak σ donation E→TM(CO)3q. The relative strength of the four bonding components depends on the charge of the system, the transition metal TM and the group-13 atom E.

Synthesis and characterization of heterometallic complexes involving coinage metals and isoelectronic Fe(CO), [Mn(CO)] and [Fe(CO)CN] ligands.

The chemistry of coinage metal ions with Fe(CO), [Mn(CO)] and [Fe(CO)CN] has been explored using MesP and N-heterocyclic carbene supporting ligands. A comparison of [(SIPr)Au-Fe(CO)][SbF], [(CAAC)Au-Fe(CO)][SbF] and [(MesP)Au-Fe(CO)][SbF] shows that the ligand donor strength towards Au(i) follows the order MesP > CAAC > SIPr. These Fe(CO) complexes show significant blue shifts in [small nu, Greek, macron] bands relative to those observed for free Fe(CO) as a result of it serving as a net electron donor to Au(i).

Novel acyloxy derivatives of branched mono- and polyol esters of sal fat: multiviscosity grade lubricant base stocks.

Sal fat, a nontraditional seed oil, was chemically modified to obtain base stocks with a wide range of specifications that can replace mineral oil base stocks. Sal fatty acids were enriched to 72.6% unsaturation using urea adduct method and reacted with branched mono alcohol, 2-ethylhexanol (2-EtH), and polyols namely neopentyl glycol (NPG) and trimethylolpropane (TMP) to obtain corresponding esters.