12.1 Introduction
The design and synthesis of new types of synthetic macrocyclic receptors with novel
and intriguing structures is always a popular topic in macrocyclic and supramolecular chemistry. The most well-known supramolecular hosts, including cyclodextrins
(CDs), crown ethers, calix[n]arenes, and cucurbit[n]urils (CBs), are widely investigated as building blocks for molecular recognition [1], self-assembly [2], smart
materials [3–6], drug delivery [7, 8], and molecular machines [9, 10]. In recent
years, some new synthetic macrocycles have been reported and have gained much
attention, such as Sessler’s “Texas-sized” box [11], Stoddart’s “Ex-box” [12],
Wang’s corona[n]arenes [13], Chen’s helic[n]arenes [14], Jiang’s oxatub[4]arene
[15], Flood’s cyanostar [16], and others [17, 18].
Macrocyclic arenes, including calixarenes [19], resorcinarenes [20], cyclotriveratrylenes [21], pillararenes [18, 22], etc. [23, 24] (Scheme 1), have been significantly
important supramolecular macrocycles over the past decades. They are all composed
of mono-benzene and mono-heterocycle units bridged by methylene. Meanwhile,
they possess π-electron rich cavities, which can capture cationic guests driven by
cationÁ Á Áπ interactions. Furthermore, one important feature of macrocyclic arenes
is that they can be readily modified with certain functional groups to improve the
solubility, host–guest binding ability, and self-assembly characteristics.
In 2015, we reported a new class of macrocyclic host compounds, namely
“4,4
0 -biphen[n]arenes,” which are based on the 4,4
0 -dialkoxy or hydroxy biphenyl
monomer [25]. In 2017, we introduced another type of biphenarenes, 2,2
0 -biphen[n]
arenes, to the supramolecular world [26]. Very recently, extended biphen[n]arenes
(e.g., terphen-[n]arenes and quaterphen[n]arenes) were designed and synthesized by
our group [27] (Scheme 2). Biphen[n]arenes have similar advantages as other typical
macrocyclic arenes such as one-pot synthesis, versatile functionality, and superior
Scheme 1 Structures of some typical macrocyclic arenes
312
B. Li et al.
The design and synthesis of new types of synthetic macrocyclic receptors with novel
and intriguing structures is always a popular topic in macrocyclic and supramolecular chemistry. The most well-known supramolecular hosts, including cyclodextrins
(CDs), crown ethers, calix[n]arenes, and cucurbit[n]urils (CBs), are widely investigated as building blocks for molecular recognition [1], self-assembly [2], smart
materials [3–6], drug delivery [7, 8], and molecular machines [9, 10]. In recent
years, some new synthetic macrocycles have been reported and have gained much
attention, such as Sessler’s “Texas-sized” box [11], Stoddart’s “Ex-box” [12],
Wang’s corona[n]arenes [13], Chen’s helic[n]arenes [14], Jiang’s oxatub[4]arene
[15], Flood’s cyanostar [16], and others [17, 18].
Macrocyclic arenes, including calixarenes [19], resorcinarenes [20], cyclotriveratrylenes [21], pillararenes [18, 22], etc. [23, 24] (Scheme 1), have been significantly
important supramolecular macrocycles over the past decades. They are all composed
of mono-benzene and mono-heterocycle units bridged by methylene. Meanwhile,
they possess π-electron rich cavities, which can capture cationic guests driven by
cationÁ Á Áπ interactions. Furthermore, one important feature of macrocyclic arenes
is that they can be readily modified with certain functional groups to improve the
solubility, host–guest binding ability, and self-assembly characteristics.
In 2015, we reported a new class of macrocyclic host compounds, namely
“4,4
0 -biphen[n]arenes,” which are based on the 4,4
0 -dialkoxy or hydroxy biphenyl
monomer [25]. In 2017, we introduced another type of biphenarenes, 2,2
0 -biphen[n]
arenes, to the supramolecular world [26]. Very recently, extended biphen[n]arenes
(e.g., terphen-[n]arenes and quaterphen[n]arenes) were designed and synthesized by
our group [27] (Scheme 2). Biphen[n]arenes have similar advantages as other typical
macrocyclic arenes such as one-pot synthesis, versatile functionality, and superior
Scheme 1 Structures of some typical macrocyclic arenes
312
B. Li et al.