Photoresponsive Supramolecular Polymers: From Light‐Controlled Small Molecules to Smart Materials

Abstract

and metal-ligand complexation [24] are attractive noncovalent interactions to enable the formation of supramolecular polymers. There are diverse groups that offer proper hydrogen bonds, for instance, amide, urea, ureidopyrimidinone (UPy), and barbituric acid derivatives. [13][14][15][16]25] Perylene bisimides and naphthalene bisimides are widely used in supramolecular polymers to provide π-π stacking moieties. [17,18] Pyridine and pyrrole are extensively studied units to coordinate with metals, i.e., Pt II , Zn II , and Cu II , which derivatives of terpyridine and porphyrin are potent ligands in supramolecular polymers. Cyclodextrins (CD), cucurbiturils, and calixarenes are the most representative host molecules in host-guest assemblies. [20][21][22][23] In many supramolecular polymers and assemblies, two or more noncovalent interactions are combined in one system. [17,[26][27][28] For instance, benzene-1,3,5-tricarboxamides (BTAs) provide both π-π stacking and hydrogen bonding for supramolecular polymers. [28] The reversible interaction between monomers enables their response to various stimuli, and therefore these polymers can function as smart and dynamic materials. [29][30][31][32][33] Among these stimuli, light has distinct advantages in controlling the supramolecular polymer and materials' organization and properties with high spatiotemporal precision. [34,35] In addition, the photochromic reactions of molecular switches and motors are reversible and can be controlled with high spatiotemporal precision and noninvasive manner. When a selective photochemical process occurs, it could avoid generating waste compared to most chemical-responsive systems. Due to these advantages, photoresponsive supramolecular polymers have attracted increasing interest either in fundamental studies or toward responsive materials in controlling macroscopic functions by light. Photoresponsive supramolecular polymers can be constructed through supramolecular homopolymerization of light-activated monomers (Figure 1). They can also be formed by co-assembling photochromic molecules with photoinactive monomers via noncovalent bonds (Figure 1). Compared with photoresponsive covalent polymers and crosslinked polymer networks, supramolecular polymers exhibit excellent dynamic properties. The conversion of small molecules to supramolecular polymers is reversible, which might offer distinct advantages with respect to reconfiguration and adaptive Photoresponsive supramolecular polymers are well-organized assemblies based on highly oriented and reversible noncovalent interactions containing photosensitive molecules as (co-)monomers. They have attracted increasing interest in smart materials and dynamic systems with precisely controllable functions, such as light-driven soft actuators, photoresponsive fluorescent anticounterfeiting and light-triggered electronic devices. The present review discusses light-activated molecules used in photoresponsive supramolecular polymers with their main photo-induced changes, e.g., geometry, dipole moment, and...

Conducting 2D Nanosheets: Photo Driven Crystallinity in Self-Assembled Cu (II) Metalated Porphyrin-Bispyridylquinoxaline

“…Therefore, these results reveal that light stimulated P Cu -DPQ have atypical self-assembled 2D nanosheets with crystallinity among others. Additionally, P Cu -DPQ entails distinct charge separation in donor and acceptor which promotes the potential structure for improvement of electronic properties in organic electronics. − …”

Defining Unidirectional Motions and Structural Reconfiguration in a Macrocyclic Molecular Motor

“…For the latter types of energy-driven molecular systems, the next necessary step is transmission of directional motions to places further away from where these motions are initially generated . This can be done in an up-scaling fashion by the transmission of the geometric state changes to an ordered environment, e.g., liquid crystals, , polymers, , or on surfaces . However, in less organized environments such as simple liquid solvents, transmission of motions at the molecular scale needs to be controlled more tightly in order not to diffuse the directional motion away by the action of the Brownian storm.…”

Flexible Azo-Polyimide-Based Smart Surface with Photoregulatable Surface Micropatterns: Toward Rewritable Information Storage and Wrinkle-Free Device Fabrication

“…31−34 To date, numerous outstanding studies have been conducted on novel photoresponsive polymers bearing azobenzene groups as side chains for applications in the fabrication of functional devices and smart surfaces. 35,36 For example, Tian et al reported a simple strategy for the fabrication of novel photoresponsive semiconductor devices via incorporation of two types of azobenzene groups in the side chain of the conjugated D−A polymer. 37 Li et al synthesized two kinds of azobenzene side-chain polymers with photoswitchable chiroptical properties, which have potential application in the development of functional optoelectronic devices.…”

“…Among them, photoresponsive materials have attracted extensive attention because light is a kind of green and environmentally friendly clean energy that can be regulated remotely, rapidly, and accurately. − Compared to the photoresponsive inorganic transition-metal oxide, photoresponsive organic molecules with reversible conformational changes, such as spiropyran, , diarylethenes, , and azobenzene, − have been widely used in controllable liquid transport, information storage, sensors, anticounterfeiting, , etc. In particular, the azobenzene and its derivatives demonstrate the obvious variation of the spatial structure and the dipole moments between the stable trans state and the metastable cis state, which endows the azobenzene-containing materials with fascinating properties of a reversible structural change or surface properties upon photoirradiation. − To date, numerous outstanding studies have been conducted on novel photoresponsive polymers bearing azobenzene groups as side chains for applications in the fabrication of functional devices and smart surfaces. , For example, Tian et al reported a simple strategy for the fabrication of novel photoresponsive semiconductor devices via incorporation of two types of azobenzene groups in the side chain of the conjugated D–A polymer . Li et al synthesized two kinds of azobenzene side-chain polymers with photoswitchable chiroptical properties, which have potential application in the development of functional optoelectronic devices .…”