potential applications in many fields, such as optoelectronic devices, fluorescence
sensing, and imaging agents [4]. Due to the introduction of many functional
units [5], reports on supramolecular polymers will be further explored because
of its luminescent properties.
Herein, we discussed an overview of the photoresponsive supramolecular systems induced by the host–guest interaction. The host–guest recognition is an important noncovalent bonding using hosts such as CD, CB, crown ether, calixarene, and
pillararene to encapsulate the guests in the constructed supramolecular system.
Furthermore, the guest unit undergoes a reversible structure or conformation difference under specific light stimulation, resulting in the corresponding changes of the
supramolecular polymer. In this chapter, we introduce the photoresponsive supramolecular systems according to the different types of hosts and make summaries and
outlooks on its functions and applications.
16.2 Photoresponsive Supramolecular Polymers Based on
Cyclodextrin (CDs)
CDs are a class of widely used supramolecular macrocyclic host molecules,
which are cyclic oligomers composed of α-(1-4)-glycosidically linked
glucopyranose units. In the structure of the CD, there is a hydrophilic surface
and a hydrophobic cavity, and its hydrophobic cavity can form an inclusion in
water with a series of organic molecules. Because of this unique advantage of CD,
scientists have linked it to the phosphorescent emission of organic molecules.
Reports on CD-induced room temperature phosphorescence (CD-RTP) were first
published in the early 1980s [6]. In 2011, we also reported a RTP addressing
pseudorotaxane induced by the inclusion of β-CD and α-BrNp. After that, we
constructed a supramolecular hydrogel system capable of rapidly self-healing and
room temperature phosphorescence based on the action of β-CD and α-BrNp [7].
For a supramolecular system based on the action of the host and guest,
the host molecule can be selected based on the size of the cavity of the macrocyclic
molecule. The cavity size of the γ-CD molecule is 0.75 nm, which is much larger than
that of α-CD and β-CD. The structures and related properties of CDs are shown in Fig. 1.
16.2.1 CD-Based Polymer Networks and Hydrogels
Many photoresponsive supramolecular polymer systems in side-chain are based
on cyclodextrin because of its high solubility and protective effect on the optical
signal. Herein, we introduce the cyclodextrins interacted with the corresponding
object to achieve light response control. In 2015, Wu et al. [8] reported a
novel supramolecular complex which is formed by tetra-ortho-methoxy-substituted
azobenzene (mAzo) and β-cyclodextrin (β-CD), shown in Fig. 2. They synthesized a
mAzo-functionalized polymer and a β-CD-functionalized polymer and obtained the
supramolecular hydrogels by mixing the two polymers. The supramolecular
16 Photoresponsive Supramolecular Polymers Based on Host-Guest Interactions
453
sensing, and imaging agents [4]. Due to the introduction of many functional
units [5], reports on supramolecular polymers will be further explored because
of its luminescent properties.
Herein, we discussed an overview of the photoresponsive supramolecular systems induced by the host–guest interaction. The host–guest recognition is an important noncovalent bonding using hosts such as CD, CB, crown ether, calixarene, and
pillararene to encapsulate the guests in the constructed supramolecular system.
Furthermore, the guest unit undergoes a reversible structure or conformation difference under specific light stimulation, resulting in the corresponding changes of the
supramolecular polymer. In this chapter, we introduce the photoresponsive supramolecular systems according to the different types of hosts and make summaries and
outlooks on its functions and applications.
16.2 Photoresponsive Supramolecular Polymers Based on
Cyclodextrin (CDs)
CDs are a class of widely used supramolecular macrocyclic host molecules,
which are cyclic oligomers composed of α-(1-4)-glycosidically linked
glucopyranose units. In the structure of the CD, there is a hydrophilic surface
and a hydrophobic cavity, and its hydrophobic cavity can form an inclusion in
water with a series of organic molecules. Because of this unique advantage of CD,
scientists have linked it to the phosphorescent emission of organic molecules.
Reports on CD-induced room temperature phosphorescence (CD-RTP) were first
published in the early 1980s [6]. In 2011, we also reported a RTP addressing
pseudorotaxane induced by the inclusion of β-CD and α-BrNp. After that, we
constructed a supramolecular hydrogel system capable of rapidly self-healing and
room temperature phosphorescence based on the action of β-CD and α-BrNp [7].
For a supramolecular system based on the action of the host and guest,
the host molecule can be selected based on the size of the cavity of the macrocyclic
molecule. The cavity size of the γ-CD molecule is 0.75 nm, which is much larger than
that of α-CD and β-CD. The structures and related properties of CDs are shown in Fig. 1.
16.2.1 CD-Based Polymer Networks and Hydrogels
Many photoresponsive supramolecular polymer systems in side-chain are based
on cyclodextrin because of its high solubility and protective effect on the optical
signal. Herein, we introduce the cyclodextrins interacted with the corresponding
object to achieve light response control. In 2015, Wu et al. [8] reported a
novel supramolecular complex which is formed by tetra-ortho-methoxy-substituted
azobenzene (mAzo) and β-cyclodextrin (β-CD), shown in Fig. 2. They synthesized a
mAzo-functionalized polymer and a β-CD-functionalized polymer and obtained the
supramolecular hydrogels by mixing the two polymers. The supramolecular
16 Photoresponsive Supramolecular Polymers Based on Host-Guest Interactions
453