CH4@C60 was the first example an organic molecule has been embedded in C60, and by far the largest molecule. CH4 can rotate freely in the molecular cage, and the carbon skeleton structure of the C60 has no obvious deformation. The electronic structure of CH4@C60 and interaction between C60 and CH4 were studied using quantum mechanical calculation method. The different reaction sites on C-C bonds in C60 and the weak Van der Walls interaction between CH4 and C60 were shown clearly. These results and the orbital interaction between CH4 and C60 were helpful for understanding and further application of this unique biggest organic molecule CH4 contained in C60 structure so far.

A small molecule probe for simultaneous detection of HSA and SO2 via their distinct fluorescent signals was designed recently. This effective tool provided a significant boost in understand underlying mechanism of synergistic action between SO2 and HSA in disease. The structure and fluorescent character of this probe molecule were studied under density functional theory in this work. The different stable conformations of probe C23 were found through theoretical method which explained the no experimental fluorescent character of the probe itself. The electron excitation analysis indicated the charge transfer process in the restricted C23 (binding to the hydrophobic cavity of HSA) and CS (C23 reaction with SO2) when the molecules were under optical excitation. The theoretical results could be helpful for understanding the electronical properties in the probe and providing the insights for designing new probe molecules.