27443-40-9Relevant academic research and scientific papers
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.
Tropylium salts as efficient organic Lewis acid catalysts for acetalization and transacetalization reactions in batch and flow
Lyons,Crocker,Enders,Nguyen
supporting information, p. 3993 - 3996 (2017/09/08)
Acetalization reactions play significant roles in the synthetically important masking chemistry of carbonyl compounds. Herein we demonstrate for the first time that tropylium salts can act as organic Lewis acid catalysts to facilitate acetalization and transacetalization reactions of a wide range of aldehyde substrates. This metal-free method works efficiently in both batch and flow conditions, prompting further future applications of tropylium organocatalysts in green synthesis.
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.
The azulene ring as a structural element in liquid crystals
Estdale, Sian E.,Brettle, Roger,Dunmur, David A.,Marson, Charles M.
, p. 391 - 401 (2007/10/03)
A new approach to the synthesis of azulene liquid crystals is described based on Hafner's procedure involving reaction of a pyridinium salt with a cyclopentadienide. The preparation of a variety of liquid crystalline materials using this method is described. Variants are reported with single substituents on the azulene ring in the 6-position and doubly substituted in the 2,6-positions. The effect of the azulene ring as a core or dipolar terminal structural element is explored. 6-(5-Alkyl-1,3-dioxan-2-yl)azulenes are shown to exhibit smectic A phases and 2-cyclohexyl-6-(5-tridecyl-1,3-dioxan-2-yl)azulene show smectic A and B phases. Phase characterisation of the materials is recorded together with X-ray measurements on the smectic A phase of one representative compound. Results of dichroism studies on the azulene mesogens are also briefly reviewed.
