Highly Emissive Luminogens in Both Solution and Aggregate States

Organic light-emitting materials have attracted considerable attention because of their promising applications in diverse areas.Most fluorophores emit brightly in either dilute solutions or aggregate states;the former generally suffer from aggregation-caused quenching problem,and the latter encounter intensity loss at low concentrations.Herein,we propose a new strategy to overcome these dilemmas by balancing the planar and distorted structures of terphenyl-based luminogens and obtain three luminogens,2PB-AC,2Me2PB-AC,and 2T2PB-AC,with bright emission in both solution and aggregate states.Among them,2PB-AC shows absolute photoluminescence quantum yields(ФPL)higher than 90%in both tetrahydrofuran solution(90.2%)and aggregate states(92.7%for powder and 95.3%for crystal).Thus,2PB-AC could be an efficient probe to realize dual-channel explosive detection in both solution and aggregate states.Moreover,it could be used to image live-cell lipid droplets at a wide range of concentrations.In addition,benefiting from its thermodynamically favorable intersystem crossing process,2Me2PB-AC could be doped in polymethyl methacrylate matrix to provide efficient room-temperature phosphorescence.Thus,this work provides a feasible strategy for the design of luminogens with highly efficient emission in both solution and aggregate states,greatly facilitating and broadening their practical applications.

Discovery of New Thioviridamide-Like Compounds with Antitumor Activities

Thioviridamide is a structurally unique compound with potent antitumor activity.The biosynthesis of thioviridamide follows a typical pathway as ribosomally synthesized and post-transiationally modified peptides,making the genome mining-based discovery of thioviridamide-like compounds rational.Taking advantage of the linkage between the precursor peptide and the metabolite skeleton,we identified a new biosynthetic gene cluster in Streptomyces sp.NRRL S-87 that could encode thioviridamide analogues.Overexpression of the whole gene cluster led to the isolation and structure elucidation of TVA-YJ-4 and TVA-YJ-5,two novel thioviridamide-like compounds featuring N-terminal capping groups.Chemical screening of the fermentation extracts also detected TVA-YJ-6,another new thioviridamide-like compound with representative methionine sulfoxide.Detailed analysis further revealed that these structural modifications were introduced during the compound extraction process instead of through genuine enzymatic reactions.TVA-YJ-4 and TVA-YJ-5 display slightly reduced cytotoxic activities against a panel of tumor cell lines in comparison with their parental natural product,TVA-YJ-2.Our work will expand the membership of this rare class of compounds and promote related biosynthetic studies.