Precise synthesis and photophysical properties of a small chiral carbon nanotube segment: Cycloparaphenylene-2,6-naphthylene
Herein we report the precise synthesis and photophysical properties of a naphthalene-containing carbon nanohoop, cycloparaphenylene-2,6-naphthylene (CPPNa2,6), as a sidewall segment of a [9, 8] single-walled carbon nanotube ([9, 8]SWNT) by a rationally designed strategy. To the best of our knowledge, CPPNa2,6 represents the smallest chiral SWNT segment ever reported. The structure was confirmed by 1H NMR, 2D 1H-1H COSY NMR, 13C NMR, and HR-MS. The nanohoop’s interesting photophysical properties were investigated by steady-state and time-resolved spectroscopies combined with theoretical calculations. Compared with the CPP and CPP nanohoops, CPPNa2,6 has a moderate strain energy (89.6 kcal.mol-1) and a higher HOMO-LUMO gap (3.5 eV).