Professor Yang Yingwei's team of Jilin University: strong fluorescence and controllable white light emission of solid phase / solution phase assisted by aromatics

The author: Professor Yang Yingwei's team has been one of the research focuses in the field of luminescent materials, including the design and synthesis of fluorescent molecules with strong fluorescence emission in solid / solution phase and the reasonable construction of tunable white light emission system The application of synthetic macrocyclic compounds as building units in the structural modification of fluorescent molecules has great potential for the design and construction of intelligent response fluorescent materials On the one hand, the modification of supramolecular macrocycles in fluorescent molecules can affect their fluorescence properties by changing the original stacking mode; on the other hand, the combination of macrocycles and fluorescent molecules provides a binding site for the interaction between the host and the guest, and the construction of fluorescent supramolecular assemblies with stimulus responsiveness can be realized by introducing the corresponding guest, that is, by changing the solvent and pH The effective control of the fluorescence properties of these materials can be realized by the method of influencing the host guest interaction by environmental conditions such as temperature, competitive object and so on This kind of intelligent response fluorescent materials with dynamic properties have great application prospects in photoelectric devices, anti-counterfeiting printing, ion detection, cell imaging, drug delivery and so on Recently, a team of Professor Yang Yingwei from Jilin University reported the design and synthesis of anthracene containing fluorescent molecule (FH) with dark blue fluorescence and dual functionalization of aromatics Compared with the corresponding acyclic aromatic modified monomer molecule (FM), FH has strong fluorescence emission and high quantum efficiency in both solid and solution phases At the same time, the team selected three guest molecules with different fluorescent chromophores or bonding sites, and assembled them with FH respectively By adjusting the proportion of host and guest and changing the solvent system, the team obtained the fluorescent emission controllable supramolecular assembly by virtue of the fluorescent resonance energy transfer (FRET) between chromophores When DG2 and FH are assembled in toluene, white light emission with CIE coordinates of (0.31, 0.35) can be realized Figure 1 The structure of DG1, DG2, BG3, FH and FM, and the single crystal structure analysis of the supramolecular assembly of DG2 and FH (source: chem EUR J.) FH and FM show that although they have the same color group, the interaction between the intramolecular groups and the stacking mode between the molecules are obviously different Because FH molecules are modified with aromatic macrocycles at both ends, there is a certain steric hindrance in the molecules (Fig 2a), which leads to the increase of molecular rigidity At the same time, the steric hindrance effect of the macrocycles also effectively avoids the π - π accumulation between the central chromophores (Fig 2e) This unique molecular structure and intermolecular stacking is the direct reason why FH has superior fluorescence properties in both solid and solution phases Fig 2 structural diagram of FH and FM single crystal (source: Chem Eur J In each kind of assembly, changing the ratio of host and guest and the solvent in the system can effectively regulate the fluorescence emission of the system The calculation results of the radiative and non radiative transition constants of different assemblies (Fig 3) show that the host guest bond interaction and solvent effect have a synergistic effect on the FRET efficiency in the system and the overall fluorescence properties The white light emission with CIE coordinates of (0.31,0.35) was successfully realized by the assembly of DG2 and FH in toluene Figure 3 Radiation transition constant Kr, non radiation transition constant Kr, quantum efficiency, fluorescence photo and CIE coordinate data of FH, FM and different supramolecular assemblies in different solvents (chloroform and toluene) (source: chem EUR J 2019), Doi: 10.1002/chem.201902700) The first co authors of the paper are Lou Xinyue and Song Nan, postgraduates of Jilin University This work was supported by the general program of National Natural Science Foundation of China, the special fund for new materials of Jilin Province University co construction plan, and the project of Jilin University Peiying.