Liquid crystals with 1,3,4-oxadiazole units in the aromatic core have attracted considerable attention due to their rich mesophases, high photoluminescence quantum yields, good electron transporting ability and excellent thermal stabilities. In this feature article, 1,3,4-oxadiazole-based liquid crystals are classified into three categories according to their different molecular shapes and molecular weight: calamitic and discotic monomers, symmetric and non-symmetric dimers, and polymers including main-chain, side-chain and mesogen-jacketed types. The structure–property relationships of this kind of liquid crystal are discussed in-depth, with an emphasis on strategies to devise columnar and biaxial nematic mesophases with a low temperature range.

Liquid crystals based on substituted 2,5‐diaryl‐1,3,4‐thiadiazole derivatives (1a–1f, 3a and 3b) and 1,3,4‐oxadiazole analogues (2a–2f, 4a and 4b) were synthesised and characterised by ¹H, ¹³C nuclear magnetic resonance, Fourier transform infrared, mass spectrometry, high‐resolution mass spectrometry techniques and elemental analyses. The X‐ray crystal structure of 1e revealed that it contains tilted lamellar arrangement of molecules in the crystalline solid. The liquid crystal properties have been investigated by polarised‐light optical microscopy, differential scanning calorimetry and in‐situ variable‐temperature X‐ray diffraction. All compounds (except 2e and 2f) exhibited thermotropic liquid crystal behaviours with various mesophases (smectic A and C, nematic N or soft crystal E phases). Notably, the 1,3,4‐thiadiazole derivatives consistently have wider mesomorphic temperature ranges than those of the respective 1,3,4‐oxadiazole analogues. The solutions of all compounds in CH₂Cl₂ individually displayed one or two absorption bands with λ _max values at 297–355 nm and emitted with λ _max values at 363–545 nm and quantum yields of 0.12–0.73. Structure–property relationships of these compounds are discussed in the contexts of their molecular structures and weak intermolecular interactions.

The synthesis and application of promising polymeric materials–pillararene-based conjugated porous polymers–are discussed and summarized in this review.

A new class of thiophene‐based 1,3,4‐oxadiazole derivatives ( n ‐OXD‐R) and the corresponding 1,3,4‐thiadiazole derivatives ( n ‐THD‐R) was synthesised and characterised by means of ¹H NMR, ¹³C NMR, MS and HRMS techniques. Liquid crystal properties were investigated by differential scanning calorimetry, polarising optical microscopy and variable temperature X‐ray diffraction measurements. All the 1,3,4‐thiadiazole compounds ( n ‐THD‐R) exhibited enantiotropic mesophases (smectic A, smectic C and nematic phases) with wide mesomorphic temperature ranges (68.5–109.5°C). In contrast, only the oxadiazole compounds 8‐OXD‐Cl, 9‐OXD‐Cl and 10‐OXD‐Cl, bearing electron‐withdrawing terminal group and longer alkoxy chain, displayed an enantiotropic smectic A phase with narrow mesomorphic temperature ranges (4.1–10.9°C). The effects of central heterocyclic rings, the terminal groups and the length of the terminal alkoxy on the mesomorphic behaviour are discussed.

A P(NMe₂)₃-mediated reductive intramolecular cyclopropanation is developed for the first time, which provides facile access to a wide variety of cyclopropane-fused heterocycles including chromanes, tetrahydroquinolines, lactones, and lactams. Catalytic hydrogenative ring-expansion of the cyclopropane-fused heterocycles is also elaborated, leading to various structurally important medium-sized heterocycles.