The design of molecular receptors that bind and sense anions in biologically relevant aqueous solutions is a key challenge in supramolecular chemistry. The recognition of inorganic phosphate is particularly challenging...
The photophysical properties of a series of heteroleptic Ru(II) complexes of the form [Ru(phen) 2 (phen-5,6-R 2 )] 2+ , where phen = 1,10-phenanthroline and R = phenyl (Ph), p-tert-butylbenzene (p-Ph-tBu), p-methoxybenzene (p-Ph-OMe), and 2-naphthalene (2-naph), have been measured. Variation of the R group does not greatly perturb the electronic properties of the ground state, which were explored with electronic absorption and resonance Raman spectroscopy and are akin to those of the archetypal parent complex [Ru(phen) 3 ] 2+ . All complexes were shown to possess emissive 3 MLCT states, characterized through transient absorption and emission spectroscopy. However, an additional, long-lived excited state was observed in the Ru(II) naphthalene complex. The naphthalene substituents facilitate population of a 40 μs dark state which decays independently to that of the emissive 3 MLCT state. This state was characterized as 3 LC in nature, delocalized over the naphthalene substituted ligand.
Organic
redox flow batteries are currently the focus of intense
scientific interest because they have the potential to be developed
into low-cost, environmentally sustainable solutions to the energy
storage problem that stands in the way of widespread uptake of renewable
power generation technologies. Because the search space of suitable
redox-active electrolytes is large, computational screening is increasingly
being employed as a tool to identify promising candidates. It is well
known in the computational chemistry literature that redox potentials
for organic molecules can be accurately calculated on a class-by-class
basis, but the general utility and accuracy of the relatively low-cost
quantum chemical methods used in high-throughput screening are currently
unclear. In this work, we measure the redox potentials of 24 commonly
available but chemically diverse redox-active organic molecules in
acetonitrile, carefully controlling experimental errors by using an
internal reference (a ferrocene/ferrocenium redox couple), and compare
these with redox potentials computed at B3LYP/6–31+G(d,p) using
a polarizable continuum model to account for solvation. Unlike previous
large-scale computational screening studies, this work carefully establishes
the accuracy of the computational procedure by benchmarking against
experimental results. While previous small-scale computational studies
have been carried out on structurally homologous compounds, this work
assesses the accuracy of the computational model across a variety
of compound classes, without applying class-dependent empirical corrections.
We find that redox potential differences for coupled one-electron
transfer processes can be computed to within 0.4 V and two-electron
redox potential differences can usually be computed to within 0.15
V.
The reaction of symmetrical ligands based on 3,6-di(2-pyridyl)pyridazine () with carbocyclic rings fused to the pyridazine ring; 7,10-di(2-pyridyl)-8,9-diazafluoranthene (), 1,4-di(2-pyridyl)-6,7-dihydro-5H-cyclopenta[d]pyridazine (), 1,4-di(2-pyridyl)-5,6,7,8-tetrahydrophthalazine (), 1,4-di(2-pyridyl)-6,7,8,9-tetrahydro-5H-cyclohepta[d]pyridazine () in reactions with zinc perchlorate gave a series of complexes (). Characterisation of these using single crystal X-ray structure determination showed that less sterically hindered and gave saturated triple helicates ( and , respectively), while [2 × 2]-grids were formed with more sterically hindered ligands ( from and from ), or if methanol (rather than acetonitrile) was used as the reaction solvent with (). The most sterically-hindered ligand formed a mononuclear complex (). The structures of these complexes in solution was determined by (1)H-NMR, and found to match their solid-state structures. The [2 × 2]-grids are effective molecular clips able to hold solvent and anions between their arms via hydrogen bonding to a Zn4(H2O)2(OH)2 core.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.