Dynamic conformational changes in the molecular rotor of the triangular-shaped AIEgens linker enable diversification of Ln-MOFs with a family of three-connected networks

AIEgens typically feature dynamic molecular rotor modules, often exhibiting non-planar and conformationally flexible molecular structures. By incorporating AIEgens into the framework of Metal-Organic Frameworks (MOFs) as functionalized linkers, one can effectively overcome the geometric constraints inherent in traditional, rigid "static" linkers, while simultaneously circumventing the major bottleneck associated with traditional organic fluorophores—namely, their propensity for fluorescence quenching in the aggregated state. The self-assembly of dynamic Lanthanide Metal-Organic Frameworks (LnMOFs)—formed by the alternating linkage of lanthanide ions or clusters (serving as Secondary Building Units, or SBUs, and possessing exceptional photophysical properties and fingerprint emission spectra) with dynamic molecular rotors (serving as linkers)—opens up new horizons for the construction of novel, intelligent luminescent materials. The degree of twisting within the molecular rotors of the AIEgen ligands—and the consequent changes in energy levels resulting from conformational shifts—enables an adaptive "antenna effect" tailored to the distinct energy levels of various lanthanide ions, thereby facilitating the effective construction of intelligent multicolor and/or chromogenic materials.

A team led by Zhong-Hong Zhu at Guangxi University in Nanning, China, utilized classic triangular triphenylamine-based AIEgens as linkers to successfully synthesize a series of Ln-MOFs featuring diverse topological connections—achieving this solely by modulating the degree of twisting of their molecular rotors. Furthermore, they demonstrated the immense potential of these materials for applications in fields such as ratiometric fluorescence sensing, multicolor displays, and information encryption.

The team published their research in Nano Research on March 27, 2026.

This study utilized the classic AIEgen 4,4′,4″-triphenylamine-tricarboxylic acid (TPA-COOH) and Ln(NO₃)₃·6H₂O (Ln = Eu, Tb) to successfully synthesize two Ln-MOFs (Eu-MOF and Tb-MOF) featuring identical topological networks via a "one-pot" solvothermal reaction. Although Eu-MOF and Tb-MOF are highly similar in their overall structures—both exhibiting a 3,8-c topological connectivity mode and a topological point symbol of {4.5²}²{4².5¹².6⁴.7⁵.8³.9²}—subtle differences exist in the dihedral angles between the phenyl rings of the AIEgens within their respective frameworks. By modulating reaction conditions to manipulate the torsion angles and conformational changes of the molecular rotor units, a series of frameworks—specifically Eu/Tb-MOF-1 and Eu-MOF-2-4—were successfully obtained. Among these, Eu-MOF-1 and Eu-MOF-3 exhibited complex 3²,8-c connectivity networks, with topological point symbols of {4².5}²{4⁴.5⁹.6⁸.7⁵.8²} and {4.5²}{4².5}{4³.5¹¹.6⁸.7³.8³}, respectively. Conversely, Eu-MOF-2/4 and Tb-MOF-1 formed even more intricate 3³,11-c connectivity networks, all sharing the topological point symbol {4.5²}{4¹¹.5¹⁴.6²⁰.7³.8⁷}{4³}². This work, for the first time, demonstrates that by controlling the torsion angles and conformational dynamics of the molecular rotor units within AIEgens, it is possible to systematically expand the family of Ln-MOFs featuring 3-c connectivity networks. AIEgens possessing distinct torsion angles exhibit differentiated energy levels, thereby enabling them to selectively match the specific excitation wavelength requirements of particular lanthanide ions. Consequently, Tb-MOF and Eu-MOF each demonstrated distinct optimal excitation wavelengths; specifically, 365 nm excitation light proved to be a better match for the energy levels of Tb(III) ions, while 410 nm Excitation at this wavelength facilitates the preferential excitation of Eu(III) ions, thereby enabling the selective regulation of luminescence in a wavelength-dependent manner. Furthermore, the Eu-/Tb-MOF exhibits distinct linear temperature responses—characterized by differing slopes—across high and low temperature regimes, rendering it suitable for the construction of dual-region ratiometric fluorescent temperature sensing systems. Notably, the Tb-MOF can be conveniently and rapidly fabricated into thin-film materials; these films retain stable and bright green luminescence even after undergoing multiple bending cycles, demonstrating excellent processability and significant potential for device applications. By manipulating reaction conditions to control the torsion angles or conformational changes of molecular rotor modules, this study has achieved the systematic construction of Ln-MOFs featuring diverse topological connectivity networks. This work not only drives substantial progress in the crystal engineering of dynamic Ln-MOFs but also opens up new horizons for the systematic development of multifunctional Ln-MOF emitters.

This work was supported by the National Natural Science Foundation of China (22505045, and 22503021), Startup Fund Guangxi University [Grant numbers ZX1080030424009 and ZX1080030424008], Natural Science Foundation of Guangxi (2025GXNSFDA069029), and Guangxi University Young and Middle-aged Teachers’ Scientific Research Basic Capacity Improvement Project (2025KY0055and 2025KY0054).

DOI Link:

https://doi.org/10.26599/NR.2026.94908442

About the Author

Zhong-Hong Zhu is an Assistant Professor at the College of Chemistry and Chemical Engineering, Guangxi University. His primary research interests focus on: (1) the construction, sensing applications, and theranostic applications of dynamic luminescent metal-organic frameworks (MOFs); and (2) the assembly mechanisms and magneto-optical properties of rare-earth coordination molecular clusters. He has authored or co-authored over 60 high-level research papers—published as the first or corresponding author—in internationally renowned journals spanning the fields of general chemistry, materials science, and nanotechnology (including Nat. Commun., Angew. Chem. Int. Ed., Adv. Mater., Coord. Chem. Rev., Adv. Funct. Mater., ACS Nano, etc.). These publications have garnered a total of over 1,400 citations, resulting in an H-index of 26, and include 3 highly cited papers. Furthermore, he serves as a peer reviewer for numerous journals—such as Nat. Commun., J. Am. Chem. Soc., Small, ACS Appl. Mater. Interfaces, Inorg. Chem. Front., Rare Metals, Inorg. Chem., Crystal Growth & Design, and CrystEngComm—and is a member of the Young Editorial Board for Chinese Chemical Letters.

About Nano Research

Nano Research is a peer-reviewed, open access, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society, published by Tsinghua University Press on the platform SciOpen. It publishes original high-quality research and significant review articles on all aspects of nanoscience and nanotechnology, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials. After 18 years of development, it has become one of the most influential academic journals in the nano field. Nano Research has published more than 1,000 papers every year from 2022, with its cumulative count surpassing 8,000 articles. In 2025 InCites Journal Citation Reports, its 2025 IF is 9.4 (8.3, 5 years), and it continues to be the Q1 area among the four subject classifications. Nano Research Award, established by Nano Research together with TUP and Springer Nature in 2013, and Nano Research Young Innovators (NR45) Awards, established by Nano Research in 2018, have become international academic awards with global influence.