Dissipative self-assembly is exploited by nature to control important biological functions, such as cell division, motility and signal transduction. The ability to construct synthetic supramolecular assemblies that require the continuous consumption of energy to remain in the functional state is an essential premise for the design of synthetic systems with lifelike properties. Here, we show a new strategy for the dissipative self-assembly of functional supramolecular structures with high structural complexity. It relies on the transient stabilization of vesicles through noncovalent interactions between the surfactants and adenosine triphosphate (ATP), which acts as the chemical fuel. It is shown that the lifetime of the vesicles can be regulated by controlling the hydrolysis rate of ATP. The vesicles sustain a chemical reaction but only as long as chemical fuel is present to keep the system in the out-of-equilibrium state. The lifetime of the vesicles determines the amount of reaction product produced by the system.

It is confirmed by measurements of fluorescence spectra and quantum yields that the fluorescence in tolan originates from the same state that causes the absorption band at lowest energy. The temperature dependence of the fluorescence quantum yield shows that this state is thermally deactivated with an activation energy of Ea = 14.0 kJ/mol. Geometry optimizations of the states SO, SI, and TI of tolan with the semiempirical AM1 method lead to planar structures with Dzh symmetry. Potential energy curves along the triple-bond stretching coordinate have been calculated for several low-lying excited states with a combination of the AM1 and the INDO/S methods. It is found that for large triple-bond lengths, the llA,-state with UT* character becomes thelowest excited singlet state. It is proposed that thermal deactivation of SI( llBlu) leads to this state. Nonvertical excitation of 11A, could explain the weak lines found in supersonic jet experiments below the onset of the llA, -l1B1,, transition.

Singlet oxygen sensitization by organic molecules is a topic of major interest in the development of both efficient photodynamic therapy (PDT) and aerobic oxidations under complete green chemistry conditions. We report on the design, synthesis, biology, and complete spectroscopic characterization (vis-NIR linear and two-photon absorption spectroscopy, singlet oxygen generation efficiencies for both one- and two-photon excitation, electrochemistry, intrinsic dark toxicity, cellular uptake, and subcellular localization) of three classes of innovative singlet oxygen sensitizers pertaining to the family of symmetric squaraine derivatives originating from pi-excessive heterocycles. The main advantage of pi-extended squaraine photosensitizers over the large number of other known photosensitizers is their exceedingly strong two-photon absorption enabling, together with sizable singlet oxygen sensitization capabilities, for their use at the clinical application relevant wavelength of 806 nm. We finally show encouraging results about the dark toxicity and cellular uptake capabilities of water-soluble squaraine photosensitizers, opening the way for clinical small animal PDT trials.