Based on our interests in the exploration about the special properties of C18 and its derivatives and our desire to provide experimental scientists with multi-perspective reference on this class of materials, we here theoretically design four C18 derivatives containing hydrogen (-H), -NH2, and/or -NO2 groups, named respectively H-C18-H, H-C18-NO2, NH2-C18-H, and NH2-C18-NO2, as shown in Scheme 1. The geometric, electronic, and optical properties of the derivatives are investigated by using density