On-Surface Synthesis of a Nonplanar Porous Nanographene

On-surface synthesis
provides an effective approach toward the
formation of graphene nanostructures that are difficult to achieve
via traditional solution chemistry. Here, we report on the design
and synthesis of a nonplanar porous nanographene with 78 sp2 carbon atoms, namely C78. Through a highly selective oxidative cyclodehydrogenation of 2,3,6,7,10,11-hexa­(naphthalen-1-yl)­triphenylene
(2), propeller nanographene precursor 1 was
synthesized in solution. Interestingly, although 1 could
not be cyclized further in solution, porous nanographene C78 was successfully achieved from 1 by on-surface assisted
cyclodehydrogenation on Au(111). The structure and electronic properties
of C78 have been investigated by means of scanning tunneling
microscopy, noncontact atomic force microscopy, and scanning tunneling
spectroscopy, complemented by computational investigations. Our results
provide perspectives for the on-surface synthesis of porous graphene
nanostructures, offering a promising strategy for the engineering
of graphene materials with tailor-made properties.