[materials] high fluorescence ink: aggregation induced luminescence effect of copper iodine complex clusters

The traditional fluorescence molecules will self quench when the concentration is high, and have aggregation induced effect (AIE) In contrast, at low concentrations, the special structural units of fluorescent molecules can rotate or vibrate freely, which will consume the excited state energy of molecules and make them return to the ground state in the way of non radiative transition, so they will not emit fluorescence; at high concentrations or in the state of aggregation, molecules are subject to physical constraints such as space potential resistance, which are consumed by non radiative transition The energy is greatly reduced, so it will emit fluorescence Since Tang benzhong reported the first aggregation induced luminescence materials, new AIE materials such as hydrocarbon AIE materials, heteroatom AIE materials, macromolecular AIE materials and metal complex AIE materials have been reported one after another Among them, although AIE materials have special properties, it is very difficult to obtain their uniform nanoparticles Compared with precious metals, copper and iodine are nontoxic and abundant elements, cu-i cluster based composite materials have excellent photoluminescence properties, which have become the object of extensive research Figure 1 Schematic diagram of ligand exchange of cu-i complex (picture source: angelw Chem Int ed 2018, accepted) Recently, Yao Hongbin group of China University of science and technology reported a simple and efficient synthesis method of soluble cu-i composite fluorescent particles and studied its AIE effect Previously reported methods of preparing cu-i cluster based fluorescent materials are mainly to synthesize insoluble powder materials, so it is impossible to study the state of these materials in solution In order to solve this problem, Professor Yao Hongbin developed a ligand exchange method, successfully prepared a variety of soluble cu-i cluster composite materials, and confined the cu-i cluster composite materials to small-sized droplets to study its AIE effect This achievement was published in Figure 2 of German Applied Chemistry (DOI: 10.1002 / anie 201802932) under the title of "highly luminescent inks: aggregation induced emission of copper – idine hybrid clusters" a) Cu-i cluster composite AIE ink preparation process; b) tem Atlas of AIE ink in different time periods; c) SEM Atlas of AIE ink in different time periods; d) PXRD Atlas of AIE ink in different time periods; E) fluorescence spectra of AIE ink in different time periods (picture source: angel Chem.int ed 2018, The author selected 0d-cu4i4 (py) 4 as the starting material This material not only has higher stability than other cu-i clusters, but also has weak binding between pyridine ligands and Cu4I4, so it is easier to exchange with other ligands In addition, P - (m-tol) 3, which has strong affinity with organic solution, is used as exchange ligand to improve the solubility of the composite in organic solution After the reaction, the author determined the ligand exchange reaction and the molecular structure of the new material through the change of powder X-ray diffraction pattern, the change of solid color, the change of solubility and crystal structure (Figure 1) After the structure and basic properties of Cu 4I 4 (P - (m-tol) 3) 4 were determined, AIE ink (Fig 2a) was prepared by using the material The morphology and fluorescence changes of the composite were monitored by transmission electron microscopy (TEM, FIG 2b), scanning electron microscopy (TEM, FIG 2C), PXRD (Fig 2D) and fluorescence spectrum (Fig 2e) The experimental results further prove that Cu 4I 4 (P - (m-tol) 3) 4 The material has good AIE effect Figure 3 A) cu-i cluster composite with different ligands; b) picture made with AIE ink; c) led light covered with AIE material; C-G) tem map of different materials (picture source: angel Chem Int ed 2018, Accepted) in addition, the author obtained composite materials with different colors by changing the kinds of ligands (Fig 3a) It was found that the complexes formed by different ligands and cu-i tetragons not only have different colors, but also have different topological structures They have 0-dimensional nanoparticle (Cu 4I 4 (3-cl-py) 4), 1-dimensional nanorod (Cu 4I 4 (PZ) 3) and 2-dimensional Nanoflake (Cu 4I 4 (PZ) 3) 4 I 4 (4,4 '- bpy) 2), which may be the reason why they emit different wavelengths of light Then, the author drew a pattern on parchment with red, yellow and blue nano materials (Fig 3b), which proved the feasibility of this material as ink Finally, the author found that the composite material can be covered on the LED chip to obtain LED chips with different luminous properties, while the Yellow AIE material attached to the blue LED can make the blue light of the LED turn into white light Therefore, this kind of fluorescent AIE composite is not only a simple aggregation induced luminescent material, but also has potential application value in anti-counterfeiting, solid-state fluorescent decoration, LED luminescent layer and other fields All authors: Chen Chen, Rui Han Li, Bai Sheng Zhu, Kun Hua Wang, Ji song Yao, Yi Chen Yin, Ming Ming Yao, Hong binyao, and Shu Hong Yu correspondence Author: Yao Hongbin