Background and Originality Content
Chirality has been widely employed in the design of novel nanomolecular
carbon structures in the fields of organic chemistry and material
science.1-3 Chiral macrocycles, in particular, offer
several advantages, such as a rigid backbone enabling a stable chiral
conformation, a terminal-less structure enabling excited states to
spread across the whole molecule, and a cavity capable of accommodating
guest molecules. However, the limited expansibility and tedious chiral
introduction of these larger carbon structures restrict their wider
application despite interest in their precise organic
synthesis.4, 5 Consequently, the translation of
molecular chirality into nanoscale chirality has been a subject of
intense current research activity. Nanogrids, an emerging area of chiral
carbon nanostructures, are powerful square carbon nanomaterials with
edges and vertices, and their extraordinary expandable skeleton allows
for constructing complex covalent nanoarchitectures.6Recently, a series of novel chiral nanogrids, including
windmill-type,7 diamond-type,8ladder-type and drawing hands-type,9, 10 have been
synthesized using Friedel-Crafts gridization. Our studies have
demonstrated the potential of ordered chiral nanogrids for stereoregular
organic nanopolymers applications.10, 11 The use of
nanogrids and gridization in constructing complex chiral
nanoarchitectures may therefore translate into a powerful molecular
installation nanotechnology.
Chirality is a ubiquitous phenomenon in nature, and is also prevalent in
the world of chemistry, particularly in many organic
compounds.12 Axial chirality, one of the most
important chiral types, has been studied for over a
century.13 Axially chiral molecule have broad
applications, including molecular sensing,14 chiral
resolution,15 chiral assembly and chemical
catalysis.16, 17 Three categories of axially chiral
molecules can be identified: biaryl axially chiral molecules (biphenyls,
binaphthylenes and heterocycles),18 olefin axially
chiral molecules (dienes, aromatic hydrocarbons and cycloalkanes) and
spiro axially chiral molecules.19, 20 Of these, biaryl
axially chiral molecules, particularly 2,2’-disubstituted derivatives of
1,1’-binaphthyl, are a versatile class of compounds that have found
applications in many areas of chemistry and
material.21 The robust configurational stability of
binaphthyl derivatives in a broad range of
conditions,22 combined with their tunable chiral
dihedral angle, makes them an ideal platform for transferring
stereoinformation and exhibiting excellent optical
properties.23 Here, we propose a fascinating class of
A-type nanogrids (AGs), which consist of difluorenyl biaromatic
derivatives (green and blue, A2 synthons which represents two reaction
sites) and thiophene derivatives (red, B2 synthons which represents two
reaction sites, Figure 1). AGs with a tunable axial chiral dihedral
angle can exhibit varying photoelectric properties. Furthermore, we
anticipate that AGs can be synthesized through an ”A2+B2” Friedel-Crafts
gridization (FCG) reaction. Our investigations revealed that FCG
provides an effective strategy for