Polarity of Ordered Solvent Molecules in 9,9'-Bianthracene Single Crystals Selects between Singlet Fission or Symmetry-Breaking Charge Separation.

Singlet exciton fission (SF) and symmetry-breaking charge separation (SB-CS) are both photophysical processes that can occur between two organic chromophores and are both of interest to improve solar energy conversion. Here, we tuned the photophysics of a 9,9'-bianthracene () single crystal between SF and SB-CS using solvent intercalation to change the electric field within the crystal. Crystals of were grown in -xylene, chlorobenzene, -dichlorobenzene, and benzonitrile, as well as solvent-free from a melt.

Controlling carbodiimide-driven reaction networks through the reversible formation of pyridine adducts.

Carbodiimides and pyridines form reversible adducts that slowly deliver carbodiimide "fuels" to out-of-equilibrium reaction networks, slowing activation kinetics and elongating transient state lifetimes. More-nucleophilic pyridines give more adduct under typical conditions. This approach can be used to extend the lifetimes of transient polymer hydrogels.

Substituent Effects on Transient, Carbodiimide-Induced Geometry Changes in Diphenic Acids.

Nucleotide-induced conformational changes in motor proteins are key to many important cell functions. Inspired by this biological behavior, we report a simple chemically fueled system that exhibits carbodiimide-induced geometry changes. Bridging via transient anhydride formation leads to a significant reduction of the twist about the biaryl bond of substituted diphenic acids, giving a simple molecular clamp.

Chemically Fueled Transient Geometry Changes in Diphenic Acids.

Transient changes in molecular geometry are key to the function of many important biochemical systems. Here, we show that diphenic acids undergo out-of-equilibrium changes in dihedral angle when reacted with a carbodiimide chemical fuel. Treatment of appropriately functionalized diphenic acids with EDC (-(3-(dimethylamino)propyl)-'-ethylcarbodiimide hydrochloride) yields the corresponding diphenic anhydrides, reducing the torsional angle about the biaryl bond by ∼45°, regardless of substitution.