Thermoswitchable fluorescence organogels based on hydrogen bond‐assisted chiral gelators

Liu, Wen Tzu; Tohnai, Norimitsu; Hisaki, Ichiro; Miyata, Mikiji; Chen, Wen Ting; Wu, Yen Jou; Liu, Jui-Hsiang

doi:10.1002/pola.26440

Cited by 5 publications

(1 citation statement)

References 44 publications

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“…Recently, we reported thermoswitchable uorescent organogels that were based on anthracene-cholesteryl carbamates in which self-assembled helical constructions formed bundles and three-dimensional networks. 6 Our research group has experience in designing photo-tunable azobenzene-cholesterolbased thermotropic liquid crystalline materials 7 by changing their structural motifs, including varying spacer lengths and linking groups (amides, esters, ethers, etc.). Thus, we aimed to implement these effects to achieve efficient gelation in this study.…”

Section: Introductionmentioning

confidence: 99%

Structure–property relationships of symmetrical and asymmetrical azobenzene derivatives as gelators and their self-assemblies

Balamurugan

Chien

et al. 2014

Soft Matter

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Two different series of symmetrical and asymmetrical azobenzenes containing terminal cholesteryl/adamantyl derivatives (SAC/SAA and AAC) with varying spacer lengths (alkyl chains) have been developed. The gelation and aggregation of these derivatives were studied relative to structural motifs, spacer lengths, solvent affinity, temperatures and light conditions. Among these derivatives, the cholesteryl derivatives that have short alkyl chains (<3) act as efficient gelators in a variety of solvents. However, the cholesteryl derivatives with longer alkyl chains (11 spacer) and adamantyl derivatives did not possess this ability. Self-assembled fibrous structures were constructed by gelators with short alkyl chains (<3), while flower-like structures were constructed by gelators with moderately longer alkyl chains (3-6) at their respective critical gelation concentrations (CGCs) according to SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy) analyses. In some cases, a partial/weak gel was observed in different solvents, which exhibited uniform spherical nanoparticles at CGCs. These nanoparticles were further entangled to form interconnected fibrous structures when the concentration was increased above the CGC (according to the SEM and TEM analyses). Secondary forces (van der Waals/H-bonding) and π-π stacking played important roles in the aggregation of both series in the solvents according to variable temperature (1)H-NMR analysis. The reversibility of sol-gel transitions by light was studied with respect to solvent affinity. This study revealed that reversible transitions were only observed in the non-polar solvents, as supported by the FTIR analysis of the gelators in the various solvents. The thermal and mesomorphic behaviors of the gelators by DSC (Differential Scanning Calorimetry) and POM (Polarized Optical Microscopy) analyses revealed that the chiral nematic (N*) and cholesteric mesophase (Ch*) were exhibited by only the short and longer alkyl chain cholesteryl derivatives, respectively. However, the cholesteryl derivative without a spacer (AAC0) did not exhibit any liquid crystalline phase but acted as an efficient gelator relative to the other gelators in this study.

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Section: Introductionmentioning

confidence: 99%

Structure–property relationships of symmetrical and asymmetrical azobenzene derivatives as gelators and their self-assemblies

Balamurugan

Chien

et al. 2014

Soft Matter

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Functional π-Gelators and Their Applications

2014

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The effect of meta versus para substitution on the aggregation of bis-cholesteryl appended 2,6-disubstituted pyridine-based gelators

2015

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The effect of meta versus para substitution on the aggregation of bischolesteryl appended 2,6-disubstituted pyridine-based gelatorsThe structurally isomeric, bent core, 2,6-disubstituted pyridine derivatives (PyPC and PyMC) were synthesized, and their gelation ability and aggregation behavior in different solvents were studied using various techniques including electron microscopy (TEM and SEM) and X-ray diffraction analysis (XRD). The PyPC was found to be soluble in most of the organic solvents studied, which may be due to the possible existence of intramolecular hydrogen bonding in PyPC (low angle) that enhanced its solubility. In contrast, 10 the PyMC was less soluble, making it a more efficient gelator than PyPC. The results from the morphological studies showed that the xerogel of PyPC in dodecanol exhibited a nanotube morphology (diameter ~70 nm), whereas PyMC in dodecanol exhibited a fibrous morphology, indicating that the existence of positional isomerism had a profound effect on the aggregation of the molecules in solution.Both right-and left-handed helical structures were observed in all gelators; however, left-handed structures were more predominant.Intermolecular hydrogen bonding as well as π-π stacking cooperatively played an important role in the aggregation of the gelators as 15 evidenced by XRD and temperature-dependent 1 H-NMR spectroscopy analyses. Based on these results, aggregation mechanisms were proposed.

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Thermoswitchable fluorescence organogels based on hydrogen bond‐assisted chiral gelators

Cited by 5 publications

References 44 publications

Structure–property relationships of symmetrical and asymmetrical azobenzene derivatives as gelators and their self-assemblies

Structure–property relationships of symmetrical and asymmetrical azobenzene derivatives as gelators and their self-assemblies

Functional π-Gelators and Their Applications

The effect of meta versus para substitution on the aggregation of bis-cholesteryl appended 2,6-disubstituted pyridine-based gelators

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