Aggregation-induced emission (AIE) is a photophysical phenomenon correlated closely with the excited-state intramolecular motions. Although AIE has attracted increasing attention due to the significant applications in biomedical and optoelectronics, an in-depth understanding of the excited-state intramolecular motion has yet to be fully developed. Here we found the non-aromatic annulene derivative of cyclooctatetrathiophene shows typical AIE phenomenon in spite of its rotor-free structure. The underlying mechanism is investigated through photoluminescence spectra, time-resolved absorption spectra, theoretical calculations, circular dichroism as well as by pressure-dependent fluorescent spectra etc., which indicate that the aromaticity reversal from ground state to the excited state serves as a driving force for inducing the excited-state intramolecular vibration, leading to the AIE phenomenon. Therefore, aromaticity reversal is demonstrated as a reliable strategy to develop vibrational AIE systems. This work also provides a new viewpoint to understand the excited-state intramolecular motion behavior of lumiongens.

Seed germination and photoautotrophic establishment are controlled by the antagonistic activity of the phytohormones gibberellins (GAs) and abscisic acid (ABA). Here we show that Arabidopsis thaliana GAS2 (Gain of Function in ABA-modulated Seed Germination 2), a protein belonging to the Fe-dependent 2-oxoglutarate dioxygenase superfamily, catalyzes the stereospecific hydration of GA₁₂ to produce GA₁₂ 16, 17-dihydro-16α-ol (DHGA₁₂). We show that DHGA₁₂, a C₂₀-GA has an atypical structure compared to known active GAs but can bind to the GA receptor (GID1c). DHGA₁₂ can promote seed germination, hypocotyl elongation and cotyledon greening. Silencing and over-expression of GAS2 alters the ABA/GA ratio and sensitivity to ABA during seed germination and photoautotrophic establishment. Hence, we propose that GAS2 acts to modulate hormonal balance during early seedling development.

Novel all-thiophene-based conjugated porous organic polymers (ThPOP-1 and ThPOP-2) were synthesized through ferric chloride-catalyzed oxidative coupling polymerization at room temperature. ThPOP-1 and ThPOP-2 were characterized via solid-state ¹³C CP/MAS NMR spectroscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and elemental analysis. The sulfur content of the obtained polymers is approximately 36 wt%. The Brunauer–Emmett–Teller specific surface area results of ThPOP-1 and ThPOP-2 are 1050 and 160 m² g⁻¹, respectively. Carbon dioxide adsorption isotherms show that ThPOP-1 (15.0 wt%) exhibits a larger uptake capacity than ThPOP-2 (4.0 wt%) at 273 K and 1.0 bar. Hydrogen uptake is also excellent for ThPOP-1 (2.23 wt%) at 77 K and 1.0 bar.

2,5-Distyryl-dithieno[2,3-b:2′,3′-d]thiophene (DEP-bt-DTT), an isomer of 2,5-distyryl-dithieno [2,3-b:3′,2′-d]thiophene (DEP-bb-DTT) and 2,5-distyryl-dithieno[3,2-b:2′,3′-d]thiophene (DEP-tt-DTT), was synthesized. Organic field-effect transistors (OFETs) based on these three isomers were fabricated. The structure cell parameters and the formation of intermolecular interactions in their single crystals show regular change when the positions of sulphur atoms vary from top–bottom–top in DEP-tt-DTT to bottom–bottom–top in DEP-bt-DTT, then to bottom–bottom–bottom in DEP-bb-DTT. Combining the results of theoretical calculations and OFET performances, it reveals that: (1) the positions of sulphur atoms determine the contribution extent of sulphur atoms to the molecular conjugation and the formation of intermolecular interactions; (2) the existence of the intermolecular interactions, especially for S–π, benefits for the charge transport; (3) the field-effect mobility (μ) increases with increasing of the sulphur atom contribution to the molecular conjugation.