Light‐Triggered Self‐Assembly of a Spiropyran‐Functionalized Dendron into Nano‐/Micrometer‐Sized Particles and Photoresponsive Organogel with Switchable Fluorescence

Chen, Qun; Yu, Feng; Zhang, Deqing; Zhang, Guanxin; Fan, Qing‐Hua; Sun, Shuna; Zhu, Daoben

doi:10.1002/adfm.200901358

Cited by 122 publications

(78 citation statements)

References 61 publications

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“…Previous work on spiropyran photochromic systems include their use for photo-induced optical sensing of metal ions, continuous flow optical sensing of solvents of different polarity [23,24], reversible photo-actuators for microfluidic applications [25][26][27], photo-chemopropulsion of microdroplets [28], and self-assembly [29,30], among others. More recently it was demonstrated that the conversion between the SP and MC form can be achieved also mechanically under tensile loading, showing the capability to create mechanochromic materials using SP containing polymers [31].…”

Section: Introductionmentioning

confidence: 99%

Microcantilever arrays functionalised with spiropyran photoactive moieties as systems to measure photo-induced surface stress changes

Grogan¹,

Florea

Koprivica

et al. 2016

Sensors and Actuators B: Chemical

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Herein we investigate the feasibility of detecting photo-induced surface stress changes using the deflection response of cantilevers. For this purpose, silicon microcantilevers have been functionalised with spiropyran photochromic molecules, using both a monolayer and a polymeric brushes approach. Upon ultraviolet light irradiation, the spiropyran unit is converted to the merocyanine form due to the photo-induced cleavage of the C spiro -O bond. The two forms of the molecule have dramatically different charge, polarity and molecular conformations. This makes spiropyrans an ideal system to study the correlation between photo-induced molecular changes and corresponding changes in surface stress. Our investigations include monitoring the changes in static cantilever deflection, and consequently, surface stress of the spiropyran functionalised cantilevers on exposure to ultraviolet light. Cantilever deflection data reveals that ultraviolet induced conformational changes in the spiropyran moiety cause a change in compressive surface 2 stress and this varies with the type of functionalisation method implemented. The change in surface stress response from the spiropyran polymer brushes functionalised cantilevers gives an average surface stress change of 98 Nm -1 (n = 8) while the spiropyran monolayer coated cantilevers have an average surface stress change of about 446 Nm -1 (n = 24) upon irradiation with UV light.

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Section: Introductionmentioning

confidence: 99%

Microcantilever arrays functionalised with spiropyran photoactive moieties as systems to measure photo-induced surface stress changes

Grogan¹,

Florea

Koprivica

et al. 2016

Sensors and Actuators B: Chemical

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“…This caused spontaneous association of MC in order to minimize the overall energy of the system. 13,16,17 In the case presented here however, these conditions are not satisfied, no spontaneous association is observed, and the turbidity of the solution exhibits good homogeneity (ESI, † Fig. S2).…”

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confidence: 97%

“…through the carboxylic acid group) and between MC-COOH molecules and water. 9,16,18 Our studies suggest that the microstructures obtained present photochromic properties not only at the liquid/air interface (ESI, † Fig. S11), but also in the solid state, see Fig.…”

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confidence: 99%

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Self-assembled solvato-morphologically controlled photochromic crystals

et al. 2014

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Here we describe, for the first time, intriguing solvato-morphological control of spiropyran-based microcrystalline structures. These microstructures exhibit reversible photoisomerization upon light irradiation (UV/Vis) in the solid-state. Finally, light-guided aggregation of these microstructures at the liquid/air interface is also demonstrated.Self-assembly is omnipresent in nature as components of any size (from molecules to galaxies) may self-assemble under favorable conditions. 1,2 From the assembly of an ant colony to the folding of a polypeptide chain into a protein, self-assembly is inspiring scientists (chemists, physicists, biologists, and materials scientists) to employ this approach as a ''bottom-up'' tool to create intriguing structures for different applications. [3][4][5] Until now, most research in self-assembly has been focused on molecular components, but more recently, the development of supramolecular chemistry and the direction of technology toward micrometer-and nanometer-scale structures have broadened this focus to include assembly of larger structures. [2][3][4] In principle, self-assembly can provide a highly innovative solution to the challenges brought by the continued drive to reduce device feature scale 6 while also providing great potential for building complex 3D microstructures in a practical way. 3Besides molecular aggregation in solution, interfacial self-assembly has attracted great interest in recent years mainly because of the creative and unique principles of this method for forming complex structures, such as self-assembled monolayers, Langmuir-Blodgett films, nanocrystals, clusters, and capsules.7 Among the self-assembly architectures, a nano-or microstructures with photo-responsive properties is of particular interest due to important potential applications in optical memories, optical switches and displays. 8,9 It is becoming increasingly obvious that the next generation of these materials will incorporate intelligent design of externally addressable photo-responsive units with self-assembly capabilities, as these can produce highly pre-organized nano-or microstructures in a spontaneous manner under the right conditions.Among the various classes of photochromic compounds, spirobenzopyrans are one of the most studied, and have been successfully used in applications such as non-linear optics, data recording, optical and electrical switching, and chemical sensing, among others. 10 The photochromic behaviour of spiropyrans is due to the reversible heterolytic cleavage and rebinding of the C spiro -O bond upon irradiation with UV light and white light, respectively (Scheme 1). These characteristics offer the possibility to modulate or switch various functions at the molecular or supramolecular level using light as the trigger. Several assemblies of spiropyran (SP) derivatives and related photomodulation have been previously reported, indicating the great potential of merocyanine (MC) to be used as a self-assembly unit. Krongauz and coworkers have described the formation of M...

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“…However, it remains a great challenge to date in the design of effective dendritic organogelators with no conventional gelation motifs such as peptide and long alkyl chains [22,23]. We previously reported a series of peripherally dimethyl isophthalate-functionalized poly(benzyl ether) dendrons, which could act as a highly efficient dendritic organogelator despite the lacking of any conventional gelating motifs [24,25]. The multiple strong - stacking interactions due to the peripheral dimethyl isophthalate motifs and non-typical hydrogen bonding were found to be the key contributor in forming the self-assembled gel.…”

mentioning

confidence: 99%

Poly(benzyl ether) dendrons without conventional gelation motifs as a new kind of effective organogelators

Liu

Wang

et al. 2012

Chin. Sci. Bull.

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Two poly(benzyl ether) dendrons, decorated in their periphery with nitrile groups, were divergently synthesized and fully characterized. Their gelation properties were studied by using scanning electron microscopy (SEM), X-ray crystal structure analysis and concentration-and temperature-dependent 1 H NMR spectroscopy. It was found that the gelation capability of these dendrons was highly dependent on dendron generation, and the second-generation dendron G 2 -CN proved to be highly efficient organogelator despite the lacking of any conventional gelation motifs, such as amides, long alkyl side chains and steroidal groups. The multiple strong - stacking interactions and hydrogen bonding interactions due to the peripheral isophthalonitrile motifs were proved to be the main driving forces to form the self-assembled gel. Over the past decades, dendritic gelators have gained much interest due to the advantages of significant steric impact and capability of forming multiple noncovalent interactions [1][2][3]. So far, a great number of physically thermo-reversible hydrogel and organogel systems based on dendrimers or dendrons with different chemical structures and functionalities have been reported [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. In 1986, Newkome and coworkers [4,5] initiated the field of dendritic supramolecular gels by reporting a series of arborol-shaped hydrogelators. Aida and co-workers [7] have reported the first example of dendritic organogel in 2000 by using an ester-terminated Fréchet-type dendrons with a dipeptide focal core. Since then, great attention has been focused on the design of novel dendritic gelators with highly gelation properties. For example, Smith and co-workers [10,11] have systematically studied both one-component and two-component dendritic gelators based on lysine. Jia and co-workers [12][13][14] have reported a series of dendritic organogel with lyotropic liquid crystals properties based on glycine and L-aspartic acid. Lately, Liu and co-workers [19] have synthesized a series of L-glutamate based aromatic dendrons as ambidextrous gelators of water and organic solvents. Among these successful examples reported, the incorporation of amide units into the core or the branches of the dendritic organogelators has been considered very necessary for the effective gelation process. However, it remains a great challenge to date in the design of effective dendritic organogelators with no conventional gelation motifs such as peptide and long alkyl chains [22,23]. We previously reported a series of peripherally dimethyl isophthalate-functionalized poly(benzyl ether) dendrons, which could act as a highly efficient dendritic organogelator despite the lacking of any conventional gelating motifs [24,25]. The multiple strong - stacking interactions due to the peripheral dimethyl isophthalate motifs and non-typical hydrogen bonding were found to be the key contributor in forming the self-assembled gel. Encouraged by these exciting results, we wish to extend such ...

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Light‐Triggered Self‐Assembly of a Spiropyran‐Functionalized Dendron into Nano‐/Micrometer‐Sized Particles and Photoresponsive Organogel with Switchable Fluorescence

Cited by 122 publications

References 61 publications

Microcantilever arrays functionalised with spiropyran photoactive moieties as systems to measure photo-induced surface stress changes

Microcantilever arrays functionalised with spiropyran photoactive moieties as systems to measure photo-induced surface stress changes

Self-assembled solvato-morphologically controlled photochromic crystals

Poly(benzyl ether) dendrons without conventional gelation motifs as a new kind of effective organogelators

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