Ambient ozone is a common pollutant in the atmosphere that has an extremely high oxidative ability, can dramatically change the structure and functionality of biomolecules, and is harmful to public health. However, the knowledge about the influence of low-level ozone is still very limited at a molecular level. In the present study, the monolayer of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC, 16:0-18:1 PC) as well as its binary mixed monolayer with 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC, 16:0 PC), which are widely found in many biological systems, have been systematically investigated in a low-level ozone environment (20 ± 10 ppb), by π-A isotherm, sum frequency generation (SFG) vibrational spectroscopy, and atomic force microscopy (AFM). Our results demonstrate that the POPC monolayer is unstable and the C═C moieties in the oleyl chain are selectively oxidized by the low-level ozone. The oxidized lipids from POPC initially remain and reorientate the hydrophilic portion to the water surface and gradually dissolve into the aqueous solution. One should take great caution when using unsaturated lipid molecules to avoid their possible oxidation in the ambient environment. The present study expands and deepens our insights into the oxidation mechanism of unsaturated lipids at a molecular level.

The high Seebeck coefficient of an I − /I 3 − thermocell was achieved by introducing host molecule PEGylated α-cyclodextrin (TEG-α-CD), which showed thermally induced phase transition. The host captures I 3 − at the cold side of the thermocell, which increased S e up to +2.4 mV/K. Notably, the maximum S e value of +4.2 mV/K was observed in the temperature range between 31 and 37 °C, which was achieved as a consequence of the phase transition between a hydrophilic phase to a hydrophobic phase. At the lower temperature side of the thermocell, the host effectively captures the I 3 − anion. Meanwhile, microphase separation of TEG-α-CD occurred at the higher temperature side, which promoted the dissociation of I 3 − . This resulted in a large concentration gap of electrochemically active I 3 − ions in between the electrodes. The power density determined for the thermoelectric cell was doubled in the presence of TEG-α-CD. This result provides a practical means to design n-type thermocells showing positive S e , only from low-molecular-weight compounds.

Supramolecular thermocell composed of I– (yellow balls), I3– (trio of red balls), I5– (five connected dark red balls) and Me18-α-CD (gray cone-shaped cylinder).

Ethylated α-cyclodextrin (Et18-α-CD) is used as a host matrix for I−/I3− thermocells.