Dong-Lin Jiang

Photoisomerization in dendrimers by harvesting of low-energy photons

Infrared radiation can induce low-frequency molecular vibrations, but, with the exception of hydrogen-bond reorganization, the excitation energy tends to be dissipated rapidly through molecular collisions rather than inducing photochemical changes. Here we show that in a macromolecular system that is designed to be insulated against collisional energy scattering, infrared absorption can excite photoisomerization by multiphoton intramolecular energy transfer. We have prepared highly branched dendrimers from aryl ethers with a photoisomerizable azobenzene core, in which infrared excitation of the aromatic units is apparently followed by a channelling of the absorbed energy to the core while the dendrimer matrix protects against collisional de-excitation. These findings suggest a strategy for harvesting low-energy photons to effect chemical transformations.

Self-assembly of a π-electronic amphiphile consisting of a zinc porphyrin–fullerene dyad: formation of micro-vesicles with a high stability

An amphiphilic zinc porphyrin-fullerene dyad appended with triethyleneglycol chains in aqueous media forms uniformly-sized multilamellar vesicles with a mean diameter of 100 nm that are thermally stable and robust against membrane lysis with surfactants.

A new approach to light-harvesting with dendritic antenna

Abstract Large aryl ether azodendrimers (LnAZO) with the number of the aromatic layers (n) larger than 4 showed a cis-to-trans isomerization upon infrared excitation (1597 cm−1) of the dendrimer matrix, whereas smaller families such as L1AZO–L3AZO were totally silent to the infrared light. The observed dependence of the isomerization rate constant on the irradiation distance suggests an unusual ‘multiphotonic’ isomerization mechanism which can overcome the activation free energy of 0.84 eV for the cis-to-trans isomerization.

A dendritic iron porphyrin as a novel haemoprotein mimic: effects of the dendrimer cage on dioxygen-binding activity

An iron(II) porphyrin 1-methylimidazole (mim) complex covalently encapsulated within a large aryl ether dendritic cage, FeII(mim)2L5, displays reversible dioxygen-binding activity, in which the dioxygen adduct survives over a period of months even in the presence of water, and exhibits a half-life of 50 h upon exposure to carbon monoxide.

Dendrimer-encapsulated iron porphyrin as a novel hemoprotein mimic for dioxygen binding

Abstract An iron(∥) porphyrin/1-methylimidazole (Im) complex, covalently encapsulated within a large aryl ether dendrimer cage ((lm)2(L5P)Fe∥), shows reversible dioxygen-binding activity, in which the dioxygen adduct ((lm)(L5P)Fe∥O2) survives over a period of months even in the presence of water. (lm)(L5P)Fe∥O2 was highly reluctant to undergo carbonylation upon exposure to a carbon monoxide atmosphere, where the half-life of (lm)(L5P)Fe∥O2 was as long as 50 hours.