27443-40-9Relevant articles and documents
Anti-Kasha's Rule Emissive Switching Induced by Intermolecular H-Bonding
Zhou, Yunyun,Baryshnikov, Gleb,Li, Xuping,Zhu, Mingjie,?gren, Hans,Zhu, Liangliang
, p. 8008 - 8016 (2018)
The exploration of emission pathways from high-excited states in organic luminogens has recently become prosperous owing to improved possibilities to study so-called anti-Kasha's rule emission with the potential of improving the luminescent quantum efficiency. However, emission pathway switching among different high-excited states has rarely been addressed through external control. We here present a rational design and synthesis of a novel azulene-based emitter to achieve a responsive control of its anti-Kasha's rule emissive switching. The emitter initially gives rise to an S3-to-S0 dominant emission as indicated by our experimental and theoretical studies. On this basis, it can be toggled into an S2-to-S0 dominant emission upon the H-bond formation between the triformyl groups and water molecules. Such a process, which originates from the H-bonding regulated distribution of excited-state energy, is accompanied by a remarkable fluorescent color conversion and a significant improvement of the fluorescent quantum yield in the azulene family. Moreover, a reversible emissive switching in doped films was observed to depend on a solid-state H-bond tuning process with moisture sensitivity. These results may provide new insight for building advanced chemical systems for visualized sensing with high distinguishability.
Synthesis of protected 5-formylpyrido[2,3-d] pyrimidine via a 2,3,4-trisubstituted pyridine using an ortho-litmation strategy; applicationtothe synthesis of a folate derivative
Watson, Samuel E.,Markovich, Anatoly
, p. 2149 - 2155 (2007/10/03)
A convenient route for the preparation of a protected 5-formylpyrido[2,3-d]pyrimidine from 2,3,4-trisubstituted pyridines has been developed. The readily available diethylacetal of pyridinc 4-carboxaldehyde is chlorinated at the 2-position and then treated with LDA and methyl chloroformate to give a 2,3,4-trisubstituted pyridine (12). Treatment of 12 with guanidine hydrochloride gives the pyrido[23-rf]pyrimidine in good yield. A 4-aminobenzoylglutamic acid side chain is installed by means of a reductive amination step to provide a 5-substituted derivative that is, after deprotection, a confonnationally unrestricted analog of 5,10-methylenetetrahydrofolate(1), the natural co-factor for thymidylate synthase, an important chemotherapeutic target in the treatment of cancer.
