Photoexcited protonated tetrathiafulvalene (HTTF) was found to act as a photosensitizer, injecting electrons into Pt microparticles (floating electrocatalysts) to produce H and TTF in acidic acetonitrile. In addition, TTF was electrochemically reduced back to TTF on a carbon electrode, to be further protonated to continuously produce H photochemically. The onset potential for the electrochemical recycling of TTF on carbon was set at a potential 500 mV more positive than the potential required for the direct reduction of protons. HTTF showed no signs of decomposition after 51 h of continuous recycling and photoinduced production of H, proving stability and reversibility.

We report the in situ self-assembly of TTF, TTF•+, and BF4 – or PF6 – into p-type semiconductors on the surface of Pt microparticles dispersed in water/acetonitrile mixtures. The visible light photoactivation of these self-assemblies leads to water oxidation forming O2 and H+, with an efficiency of 100% with respect to the initial concentration of TTF•+. TTF•+ is then completely reduced to TTF upon photoreduction with water. The Pt microparticles act as floating microelectrodes whose Fermi level is imposed by the different redox species in solution; here predominantly TTF, TTF•+, and HTTF+, which furthermore showed no signs of decomposition in solution.

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The ion transport through a bilayer lipid membrane was analyzed by an electrochemical method combined with fluorometry. The distribution of a cation and an anion predominantly determines membrane conductivity.

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The "uphill (against the concentration gradient)" accumulation of a hydrophobic cation (rhodamine 6G, R6G + ) into the inner phase of a giant unilamellar vesicle (GUV) was realized with the concentration gradient of the counter anion (X − = ClO 4 − , BF 4 − , or Br − ) in the presence of phosphate buffer (P − , pH = 7) in the inner and outer phase of the GUV and detected as the increase of the R6G + fluorescence intensity in the inner phase using a confocal laser scanning fluorescence microscope. The addition of X − in the outer phase of the GUV caused the accumulation of R6G + in the inner phase. The degree and kinetics of the accumulation were dependent on the concentration and type of X − ; e.g., the inner concentration of R6G + reached 2.5 times that in the outer phase of GUV after adding 10 mM ClO 4 − . The accumulation was theoretically simulated by assuming the distribution of ion pairs (R6G + and X − , R6G + , and P − ) between the aqueous phase and the lipid bilayer membrane (ion pair distribution model) and the transmembrane fluxes of R6G + , X − and P − . The theoretical simulation rationalized the accumulation degree and kinetics of the experimental results. The accumulation of the target cation by the concentration gradient of the counter anion demonstrated in this study can be an effective method for the preparation of liposomal drugs.