Thiophene-benzothiadiazole based donor–acceptor–donor (D-A-D) bolaamphiphiles, self-assembly and photophysical properties

ABSTRACT

Bolaamphiphilies with D-A-D type π-conjugated rigid cores composed by thiophenes as donors (D) and benzothiadiazole (BTD) as central acceptor (A) have been synthesised. Their self-assemblies and photophysical properties were investigated by polarising optical microscope, differential scanning calorimetry, X-ray diffraction and scanning electron microscopy. Such compounds can self-assemble into honeycomb cylinder mesophases with Col_hex∆/p6mm and Col_squ/p4mm lattices in their pure states as well as organogels with different morphologies in organic solvents. Their absorption spectra cover nearly the entire visible light range and their band gaps are relatively low. Tetrathiophene BTD based bolaamphilphiles (BT⁴/n) with higher D/A ratios than the bisthiophene BTD bolaamphilphiles (BT²/n) can self-assemble into more ordered nanostructures in both bulk states and solution. Both the absorption and emission peaks of BT⁴/n are strongly red shifted. The influence of the molecular conformation, the conjugated core length, as well as the D/A ratio on the self-assemble and photophysical characteristics of such D-A-D bolaamphiphiles are discussed.

GRAPHICAL ABSTRACT

KEYWORDS:

• Liquid crystal
• self-assembly
• organogel
• benzothiadiazole
• bolaamphiphile

Acknowledgments

We thank beamline 1W2A at Beijing Accelerator Laboratory and beamline BL16B1 at Shanghai Synchrotron Radiation Facility (SSRF), China.

Disclosure statement

No potential conflict of interest was reported by the authors.

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Additional information

Funding

This work was supported by National Natural Science Foundation of China (No. 21865038), Yunling Scholar Supporting Project (No. KC194320) and the Yunnan University’s Research Innovation Fund for Graduate Students (Nos. 2020204 and 2020Z51).