Project team of Xu Lin, East China Normal University: PET / ICT conversion strategy to achieve precise control of the properties of high fluorescence quantum efficiency supramolecular assembly rings

Since the Nobel Prize in chemistry was awarded to three scientists who have made outstanding contributions in the field of supramolecular chemistry in 1987, supramolecular chemistry has developed into a frontier discipline which integrates and intersects with many fields such as materials science, life science, information science and environmental science As one of the core contents of supramolecular chemistry, self-assembly is considered to be an important means to create new substances and new functions at the molecular level In recent years, chemists have constructed a large number of super molecular metal self-assembly systems with exquisite structure through coordination bond oriented self-assembly Based on its applications in sensing, catalysis, information storage, light capture, disease diagnosis and treatment, supramolecular fluorescent metal assemblies have attracted a wide range of interest However, due to the fluorescence quenching of coordination heavy metals and the dynamic reversibility of coordination bonds, the construction of supramolecular fluorescent metal assemblies with high fluorescence quantum efficiency and wide range and fine regulation of fluorescence emission wavelength has always been a difficulty and challenge in this field Xu Lin, Professor of East China Normal University, has been committed to the field of organic supramolecular chemistry, focusing on the systematic research work of supramolecular fluorescence materials chemistry Innovative achievements have been made in the research of supramolecular coordination and assembly mechanism, the strengthening of assembly material stability and the development of new assembly strategies (j.am Chem SOC., 2017, 139, 9459; j.am Chem SOC., 2018, 140, 5049; NAT Commun., 2018, 9, 3190) Prof Xu Lin, Professor of School of chemistry and molecular engineering, East China Normal University, doctoral supervisor, winner of National Excellent Youth Fund In 2012, he obtained a doctor's degree from East China University of science and Technology (Tutor: Academician Qian Xuhong), and once worked in the research group of Professor Jonathan Nitschke of Cambridge University in the UK as a postdoctoral researcher In recent years, systematic research has been carried out on the chemistry of supramolecular fluorescent materials, and 61 papers have been published in academic journals such as chem SOC Rev., J am Chem SOC., NAT Commun., etc The published papers have been cited more than 2000 times, and 8 papers published as the first / corresponding author have been selected as "ESI highly cited papers" As the editorial board member of Dalton trans., new J chem., curr Org Synth., and chin Chem Lett He has won the honorary titles of Zijiang outstanding young scholars, Shanghai "Pujiang talent" plan, young science award of East China Normal University, etc Cutting edge scientific research achievements: PET / ICT conversion strategy realizes precise regulation of the properties of supramolecular assembly rings with high fluorescence quantum efficiency Although great progress has been made in the field of supramolecular fluorescence chemistry, due to the fluorescence quenching of coordination heavy metals and the dynamic reversibility of coordination bonds, The development of novel supramolecular coordinated fluorescent assemblies with high fluorescence quantum efficiency, fine structure and performance is still a challenge in this field Through reasonable molecular design, Professor Xu Lin's research group has synthesized the super molecular fluorescent elements that can be precisely regulated by photo induced electron transfer (PET) and intramolecular charge transfer (ICT) In the process of coordination between the fluorescent element and heavy metal Pt (II), the pet effect of pyridine lone pair electron in the fluorescent element is inhibited, which leads to the improvement of fluorescence quantum efficiency after assembly (2) The coordination with pyridine will also enhance the pull electron effect of pyridine, which will lead to the increase of ICT effect, which will lead to the amplification of wavelength shift of the assembled products and the realization of fluorescence wide-range emission of supramolecular fluorescent metal assemblies It is worth noting that in the traditional PT pyridine coordination assembly, because it is difficult to realize the pet and ICT regulation of the assembly unit by pyridine group, the heavy metal effect of Pt (II) often leads to the fluorescence weakening or quenching of the supramolecular metal assembly, and it is difficult to realize the fine regulation of the fluorescence properties of the assembly Fig 1 Construction of pet and ICT tunable supramolecular fluorescent assembly (source: Nat Commun.) Fig 2 Fluorescent emission of assembly units and supramolecular assembly (source: Nat Commun.) Next, the author uses control experiments, radiative transition and non radiative transition distribution experiments, time-dependent single photon counting (TCSPC) and time-dependent density functional theory, TD-DFT) and other technologies have verified the luminescent mechanism and regulation mechanism of these supramolecular fluorescent metal assemblies Table 1 Excitation rate constant, radiation rate constant and non radiation rate constant of ligands l1-l9 and metal ring h1-h9 (source: Nat Commun) Finally, based on the excellent fluorescence performance of the series of supramolecular fluorescent metal assemblies, the author prepared a variety of supramolecular fluorescent materials such as processable fluorescent film, fluorescent ink with anti-counterfeiting printing property, etc For example, under the visual inspection, the prepared material is background white and does not show any pattern, while under the irradiation of a simple portable fluorescent meter, the prepared material immediately shows a Chinese knot pattern with different colors and strong fluorescence This series of supramolecular fluorescent materials are expected to be used in the fields of intelligent response, information storage and anti-counterfeiting of optical information Fig 3 The results of Machinable fluorescent films and fluorescent ink-jet printing materials (source: Nat Commun.) based on supramolecular fluorescent metal assembly were recently published on NAT Commun (NAT Commun., 2019, 10, 4285) Zhu Junlong, Ph.D student, School of chemistry and molecular engineering, East China Normal University, is the first author of this paper, and Professor Xu Lin and Professor Yang Haibo are co correspondents In the work, some spectral research and theoretical calculation research were supported and helped by Chen Jinquan, researcher of the State Key Laboratory of precision spectroscopy of East China Normal University, and sun Haitao, research group Nowadays, people and scientific research have been paid more and more attention in the economic life China has ushered in the "node of science and technology explosion" Behind the progress of science and technology is the work of countless scientists In the field of chemistry, in the context of the pursuit of innovation driven, international cooperation has been strengthened, the influence of Returned Scholars in the field of R & D has become increasingly prominent, and many excellent research groups have emerged in China For this reason, CBG information adopts the 1 + X reporting mechanism CBG information website, chembeangoapp, chembeango official micro blog, CBG information wechat subscription number and other platforms jointly launch the column of "people and scientific research", approach the representative research groups in China, pay attention to their research, listen to their stories, record their demeanor, and explore their scientific research spirit.