Research group of Professor Wu Tao of Suzhou University: cluster based organic framework: the largest supertetrahedral clusters of metal oxysulfide semiconductors and their unique assembly mode

The structural types of cluster units in the lead cluster based organic framework determine the later functional expansion of the framework materials to a large extent The tetrahedral tin nanoclusters (n represents the number of layers of metal) of metal chalcogenides can be regarded as fragments of traditional cubic sphalerite with the size of "quantum dot" The metal oxo-s-t-n clusters cleverly integrate oxygen and sulfur elements with different chemical properties in the traditional metal thio-t-n clusters, and realize their orderly distribution, thus providing a new way to regulate the photoelectric properties of such semiconductor materials However, up to now, the development of O-S ultra tetrahedral TN nanoclusters is slow, and their species and quantity are limited The size of the clusters is also limited to T4 clusters with 20 metal sites, and these clusters have not been integrated into the organic framework system Recently, Professor Wu Tao's research group of Suzhou University reported a case of the largest super tetrahedral oxygen sulfur cluster (t5-inso) with 35 metal sites, and successfully integrated the core-shell structure unit of "In-O @ in-s" with imidazole and carboxylic acid ligands into a multi-dimensional framework structure In particular, although carboxylic acid ligands are widely used in MOFs materials, their "marriage" with metal sulfur group nanoclusters is the first time This work provides an effective strategy for the integration of metal oxo sulfur clusters and carboxylic acid ligands, and lays a foundation for the development of new framework types in the future The results were published in J am Chem SOC (DOI: 10.1021 / JACS 8b07349) Brief introduction of Professor Wu Tao's research group Professor Wu Tao of Suzhou University founded in June 2012 At present, the research group has 1 Professor, 1 postdoctoral student, 3 doctoral students and 11 postgraduate students At present, the research group is exploring the basic research topics related to the field of chemical materials such as crystalline hybrid microporous framework materials and semiconductor nanoclusters Especially for the metal sulfur group semiconductor nanoclusters, the team has expanded the new system and structure types of such clusters, adjusted the new mode of spontaneous assembly of cluster unit framework structure, realized the cluster discretization process of reverse spontaneous assembly, expanded the limited domain function of semiconductor pore structure, and improved the cognition of structure-activity relationship of special sites in clusters, especially the development Based on this kind of discrete semiconductor clusters, the composite functional catalytic materials are developed At present, the research group has published more than 40 papers in J am Chem SOC (5 papers), angel Chem Int ed (2 papers), chem Commun (1 paper), chem Mater (2 papers) and other international chemical or Material Chemistry Journals with Suzhou University as the first communication unit Prof Wu Tao is a distinguished professor and doctoral supervisor of Suzhou University In 1999, he received a Bachelor of Science degree from Hubei Three Gorges University (now known as Three Gorges University); in 2003, he received a master of engineering degree from Shantou University; in 2003-2006, he taught in the Department of chemistry of School of science of Shantou University; in 2011, he received a Bachelor of Science degree from University of California, Riverside) received a Ph.D in science; 2011-2012 worked as a postdoctoral researcher at the University of California, riverside In 2011, he won the "national scholarship for outstanding self funded overseas students"; in 2012, he was selected into the second batch of "youth thousand talents plan" of the Central Organization Department, the core members of the introduction team of "innovation team plan" of Jiangsu Province and the high-level talents in short supply of Suzhou institutions of higher learning and scientific research institutes; in 2013, he was selected into the introduction of talents of "entrepreneurship and innovation plan" of Jiangsu Province; in 2014 It was selected into the "double hundred talents plan" of Jinjihu in Suzhou Industrial Park Professor Wu Tao has long been engaged in fundamental research work in the field of chemical materials such as crystalline hybrid microporous framework materials and semiconductor nanoclusters, especially in the construction of "precise site performance" in semiconductor nanoclusters Many pioneering contributions have been made in structure-activity relationship, solution discretization and catalytic application of discrete clusters, and multifunctional application of crystalline semiconductor framework materials At present, more than 120 jointly signed academic papers have been published in a series of international journals in the field of chemical materials, with more than 6780 citations (at present, h-index = 51) Among them, nearly 20 research papers have been published in J am Chem SOC (10), angel Chem Int ed (5), chem Mater (4) journals as the first author and corresponding author He once presided over and completed one general program of National Natural Science Foundation of China, and now presided over two general programs of National Natural Science Foundation of China and one program of Jiangsu Provincial Outstanding Youth Fund Cutting edge scientific research achievements: cluster based organic framework the largest metal oxide sulfur semiconductor super tetrahedral nano cluster and its unique assembly way since the end of last century, MOFs materials represented by HKUST-1 and MOF-5 have been reported, and the crystalline organic-inorganic hybrid framework materials have become hot and hot, and its functional research has been in full swing In view of the fact that in-situ solvothermal processes of metal sulfur group semiconductor TN clusters (Fig 1) are prone to spontaneously adopt the common angle bridging mode to form a cluster based framework structure, the academia began to realize that the framework semiconductor materials constructed by metal sulfur group semiconductor TN clusters as building units can make up for the defects of the traditional MOFs framework materials in terms of conductivity Inspired by the structural design concept of MOFs organic-inorganic hybrid materials, the metal sulfur super tetrahedral TN nanoclusters have been successfully assembled with nitrogen-containing bipyridine ligands, but only low-dimensional framework structures have been reported In 2011, Professor Pingyun Feng's research group at the University of California Riverside realized three-dimensional assembly with TN cluster for the first time using imidazole ligand (angelw Chem Int ed 2011, 50, 2536-2539) However, a large group of mainstream carboxylic acid ligands widely used in MOFs synthesis have not been able to realize the "marriage" with metal sulfur group nanoclusters Considering the configuration and component diversity of carboxylic acid ligands and metal sulfur group TN clusters, if carboxylic acid ligands can be introduced into sulfur group framework materials, a kind of hybrid framework materials with great development prospects will be obtained Fig 1 The most difficult point to realize the combination of carboxylic acid and metal sulfur group clusters is how to balance the affinity of metal oxygen bond and metal sulfur bond, which involves two key design factors: Gold species selection and fine-tuning of synthesis environment Through a large number of literature research, the research team found that the main group of metal indium (in) has achieved great success in the construction of sulfides and MOFs Combined with the previous research on oxygen sulfur clusters, the research team concluded that indium has a good affinity for oxygen and sulfur In terms of synthesis, the research group summarized the synthesis conditions of sulfides and MOFs: organoamines are mostly used as solvents and templates for the synthesis of metal sulfur clusters, and super alkaline organic solvents are conducive to the assembly of clusters and organic ligands; DMF is the most commonly used solvent in the synthesis of MOFs materials Therefore, the research group cleverly combined the synthesis conditions of MOFs and metal sulfur group clusters, and finally realized the first "marriage" between homobenzoic acid and super tetrahedral T5 inSo oxygen sulfur clusters by adjusting the ratio of DMF and super alkali solvent In addition, the team has also obtained a chiral framework system composed of t5-inso oxygen sulfur cluster and imidazole ligand (Fig 2) The conductance experiment of ios-1 single crystal fully confirmed the semiconductor characteristics of the framework material of carboxyl bridge cluster (Fig 3) Fig 2 (a) two dimensional assembly of T5 oxo sulfur cluster and pyromellitic acid; (b) three dimensional assembly of T5 oxo sulfur cluster and imidazole (source: j.am Chem SOC.) Fig 3 Arrhenius diagram of carboxylic acid ligand ios-1 and conductivity test of single crystal (source: j.am Chem SOC.) in fact, it was formed in situ in the process of solvothermal assembly T5-inso cluster is also a classic case of the size expansion of TN type oxygen sulfur cluster system In the early exploration of high valence metal based TN clusters, it was found that O 2-ions can be inserted into the "adamantane" cage center of tetrahedral clusters For example, Professor Krebs group of Bielefeld University completed the preparation of oxygen inserted T3 snseo clusters as early as 1975; in 1999, Professor ozin group of University of Toronto filled the oxygen inserted T2 snseo clusters Although o 2-ion can effectively alleviate the excess of the positive charge of the high valence metal in the cluster, in many successful examples of "oxygen sulfur coupling" type TN clusters, the metal components are mainly concentrated in the IV valence metal (SN 4 +) Even if the insertion type O 2-reduces the positive charge in the core region of the cluster, it is not enough to achieve a significant reduction, so the breakthrough of the size of the TN oxo-s cluster still faces great challenges In 2016, Professor Zhang Xianmin's research group of Shanxi Normal University cleverly used the strategy of Sn4 + / in3 + mixed metal, successfully broke through the size of oxygen sulfur clusters, and obtained the first T4 sninso nano cluster It is worth mentioning that the core site of the oxygen sulfur cluster (originally occupied by μ 4 - S 2 -) is in a vacancy state The group of Wu Tao, Professor of Suzhou University, has successfully synthesized the first t5-inso oxygen sulfur cluster by using only in 3 + ions In 3 + of the core site of the new t5-inso cluster is surrounded by four inserted oxygen and four substituted oxygen, forming a unique "In-O @ in-s" core-shell structure This structural model successfully breaks the magic spell that the high valence metal in3 + cannot appear in the core site of T5 cluster (Figure 4) Figure 4 In 13 o 8 nucleus (source: j.am Chem SOC.) in various O-S supertetrahedral clusters and T5 O-S clusters Conclusion: in terms of structure, this work has achieved three breakthroughs: 1 It has created the largest metal O-S supertetrahedral nanoclusters so far; 2 It is the first time in TN, except for insertion type oxygen Substitutional oxygen was found in the oxygen sulfur cluster system, and the stability of high valence metals in the core site of T n cluster was realized; 3 In view of the diversity of carboxylic acid ligands, the synthesis strategies and reaction media involved in this work provide an effective reference for the creation of new inorganic organic hybrid framework materials with metal sulfur group nanoclusters as cluster units Yang Huajun, a member of Professor Wu Tao's team, and Zhang Jiaxu, a graduate student, are the first adults to complete the research At the same time, the research was supported by the National Natural Science Foundation of China, Jiangsu Science outstanding youth fund and Jiangsu higher education institution key discipline development fund The results were published in J am Chem SOC (DOI: 10.1021 / JACS 8b07349) 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, under the background of pursuing innovation driven, international cooperation has been strengthened, and returned personnel are leading in R & D