Herein we successfully developed a ring-fusion approach to extend the conjugation length of phenothiazines and synthesized a series of novel extended phenothiazines 1–5. The intriguing π-conjugation length-dependent photophysical and redox...
Metal-organic frameworks (MOFs) consisting of organic radicals are of great interest because they have exhibited unique and intriguing optical, electronic, magnetic, and chemo-catalytic properties, and thus have demonstrated great potential applications in optical, electronic, and magnetic devices, and as catalysts. However, the preparation of MOFs bearing stable organic radicals is very challenging because most organic radicals are highly reactive and difficult to incorporate into the framework of MOFs. Herein we reported a post-synthetic modification strategy to prepare a novel MOF containing phenazine radical cations, which was used as heterogeneous catalyst for aza-Diels-Alder reaction. The zinc-based metal-organic framework Zn 2 (PHZ) 2 (dabco) (N) was successfully synthesized from 5,10-di(4-benzoic acid)-5,10-dihydrophenazine (PHZ), triethylene diamine (dabco) with Zn(NO 3 ) 2 • 6H 2 O by solvothermal method. The as-synthesized MOF N was partially oxidized by AgSbF 6 to form MOF R containing ~10% phenazine radical cation species. The resultant MOF R was found to keep the original crystal type of N and very persistent under ambient conditions. Consequently, MOF R was successfully employed in radical cation-catalyzed aza-Diels-Alder reactions with various imine substrates at room temperature with high reaction conversion. Moreover, heterogeneous catalyst MOF R was reusable up to five times without much loss of catalytic activity, demonstrating its excellent stability and recyclability. Therefore, the post-synthetic modification developed in this work is expected to become a versatile strategy to prepare radicalbased MOFs for the application of heterogeneous catalysts in organic synthesis.
A fluorescent probe based on tetrahydroxanthylium–coumarin was designed and synthesized for the detection of bisulfite in an aqueous solution and mitochondria.
The organometallic compounds of lithium ions have garnered continuous interest as indispensable precursors for the syntheses of organometallic complexes of main-group metals, transition metals, lanthanide metals, and actinide metals. In this work, we present a strategy for the preparation of a series of polynuclear lithium complexes. This methodology features the utilization of organolithium reagents both as metal sources to coordinate with the ligands and as nucleophilic reagents to undergo nucleophilic addition to the C�N bonds of the ligands. Reaction of a ligand HL1amino)phenol]. One prominent feature regarding the formation of 1•1.5Tol is the occurrence of nucleophilic addition of n-BuLi to the C�N bond of HL1, leading to the generation of a new [L1a] 2− ligand that contains both aminophenol and 1-(2-pyrrolyl)alkylamine scaffolds. The developed protocol can be adapted to a series of organolithium reagents. Compounds [Li 8 (L1b) 4 ] (2) and [Li 8 (L1c) 4 ] (3) were afforded by treatment of HL1 with sec-BuLi and LiCH 2 SiMe 3 , respectively. Reaction of an analogous ligand HL2 [HL2 = 2-(((1-(2-(dimethylamino)ethyl)-1H-pyrrol-2yl)methylene)amino)-4-methylphenol] with n-BuLi generated compound [Li 8 (L2a) 4 ] ( 4). C�N bond activation was not observed in the reaction of HL1 with NaO t Bu, and the complex [Na 4 (L1) 4 ]•Tol (5•Tol) was obtained. A decanuclear complex [Li 10 (L3a) 2 (L3b) 2 ] (6) was also prepared via the reaction of HL3 [HL3 = 2-(2-((((1H-pyrrol-2-yl)methylene)amino)methyl)-1Hpyrrol-1-yl)-N,N-dimethylethan-1-amine] with t-BuLi. A remarkable feature in terms of the synthesis of 6 is the simultaneous occurrence of hydrogen atom abstraction from the C−H bond of the pyrrolyl ring and nucleophilic addition to the C�N bond of the HL3 ligand by t-BuLi. A series of amines containing biologically and physiologically important moieties were achieved by hydrolysis of the crude products from the reactions of the HL1−HL3 ligands and organolithium reagents. This work provides an efficient approach to high-nuclearity lithium compounds as well as a series of amines.
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