Stimuli-fluorochromic smart organic materials.

Smart materials based on stimuli-fluorochromic π-conjugated solids (SFCSs) have aroused significant interest due to their versatile and exciting properties, leading to advanced applications. In this review, we highlight the recent developments in SFCS-based smart materials, expanding beyond organometallic compounds and light-responsive organic luminescent materials, with a discussion on the design strategies, exciting properties and stimuli-fluorochromic mechanisms along with their potential applications in the exciting fields of encryption, sensors, data storage, display, green printing, etc. The review comprehensively covers single-component and multi-component SFCSs as well as their stimuli-fluorochromic behaviors under external stimuli. We also provide insights into current achievements, limitations, and major challenges as well as future opportunities, aiming to inspire further investigation in this field in the near future. We expect this review to inspire more innovative research on SFCSs and their advanced applications so as to promote further development of smart materials and devices.

pH-Modulated 1D Hierarchical Self-Assembly of a Brush-Like Poly-Para-Phenylene Homopolymer.

The controllable self-assembly of conjugated homopolymers, especially homopolymers without other segments (a prerequisite for phase separation), which can afford chances to achieve tunable optical/electronic properties, remains a great challenge due to their poor solubility and has remained rarely documented. Herein, a conjugated homopolymer (DPPP-COOH) is synthesized, which has a unique brush-like structure with a conjugated dendritic poly-para-phenylene (DPPP) backbone and alkyl-carboxyl side chains at both edges of the backbone. The introduction of carboxyl makes the brush-like homopolymer exhibit pH-modulated 1D hierarchical self-assembly behavior in dilute solution, and allows for flexible morphological regulation of the assemblies, forming some uncommon superstructures including ultralong nanowires (at pH 7), superhelices (at pH 10) and "single-wall" nanotubes (at pH 13), respectively. Furthermore, the good aqueous dispersibility and 1D feature endow the superstructures formed in a high-concentration neutral solution with high broad-spectrum antibacterial performance superior to that of many conventional 1D materials.