- Hydrogen Bonding-Induced H-Aggregation for Fluorescence Turn-On of the GFP Chromophore: Supramolecular Structural Rigidity
-
To turn on the fluorescence of the native green fluorescence protein (GFP) chromophore, 4-hydroxybenzylidene-dimethylimidazolinone (HBDI), in an artificial supramolecular system has been a challenging task, because it requires high local environmental rigidity. This work shows that the formation of H-aggregates of an HBDI-containing organogelator results in two orders of magnitude fluorescence enhancement (Φf=2.9 vs. 0.02 %), in which the inter-HBDI OH???OH H-bonds play a crucial role. The aggregation-induced fluorescence enhancement of HBDI has important implications on the origin of the high fluorescence quantum efficiency of HBDI in the GFP β-barrel and on the supramolecular strategy for a full fluorescence recovery of HBDI. These results reveal a new approach to designing rigid chromophore aggregates for high-performance optoelectronic properties.
- Tsai, Meng-Shiue,Tsai, Sung-Yu,Huang, Yi-Fan,Wang, Chien-Lung,Sun, Shih-Sheng,Yang, Jye-Shane
-
supporting information
p. 5942 - 5945
(2020/03/30)
-
- Olefin Amine (OLA) Reagents for the Synthesis of Bridged Bicyclic and Spirocyclic Saturated N-Heterocycles by Catalytic Hydrogen Atom Transfer (HAT) Reactions
-
Spiro- and bridged bicyclic structures are in demand for their sp3-rich frameworks that offer unique physiochemical properties and precisely positioned substituent groups. In order to rapidly access such molecules in a cross-coupling fashion we describe olefin amine (OLA) reagents for the transformation of aldehydes and ketones into all three topological types of bicyclic N-heterocycles: bridged, spiro-, and fused rings. The OLA reagents are easily prepared and allow the synthesis of complex molecular frameworks under operationally simple conditions that tolerate a wide array of functional groups. Investigations into the Mn or Fe promoted reaction pathway support a metal hydride hydrogen atom transfer (MH-HAT) to generate a C-centered radical that undergoes addition to an unactivated imine, leading to an N-centered radical. A catalytic cycle featuring regeneration of the metal catalyst by O2 and a second HAT to form the unprotected saturated N-heterocycle appears to be operative.
- Wang, Ya-Yi,Bode, Jeffrey W.
-
supporting information
p. 9739 - 9745
(2019/06/17)
-
- Synthesis and antimalarial activity of new nanocopolymer β-lactams and molecular docking study of their monomers
-
This report describes the preparation of some new β-lactam nanocopolymers. These nanoparticles are synthesized in water by emulsion polymerization of an acrylate β-lactam pre-dissolved in a mixture of co-monomers in the presence of sodium dodecyl sulfate as a surfactant and potassium persulfate as a radical initiator. Dynamic light scattering analysis and electron microscopy images of these emulsions show that the nanoparticles are approximately 30-70 nm in diameter. These compounds have been evaluated for their antimalarial activities against chloroquine-resistant Plasmodium faliparum K1 strain demonstrating IC50 varying from 14 to 50 μM. The interactions between these β-lactam nanocopolymers and the P. falciparum single-stranded DNA-binding proteins have been studied by molecular docking calculations.
- Ebrahimi, Edris,Jarrahpour, Aliasghar,Heidari, Nahid,Sinou, Véronique,Latour, Christine,Brunel, Jean M.,Zolghadr, Amin R.,Turos, Edward
-
p. 247 - 262
(2016/01/25)
-
- An efficient microwave method for the synthesis of imines
-
A large variety of aryl and heterocyclic chiral and achiral imines can be generated simply, efficiently, and cleanly through the use of microwave irradiation and the use of a small amount of molecular sieve. Reactions are rapid and complete in a matter of minutes, and can be quantitative, reducing significantly the time and amount of solvents used in compound isolation and purification.
- Border, Emily C.,Blair, Victoria L.,Andrews, Philip C.
-
p. 844 - 848
(2015/05/20)
-
- A modular lead-oriented synthesis of diverse piperazine, 1,4-diazepane and 1,5-diazocane scaffolds
-
Piperazines are found widely in commercially-available compounds and bioactive molecules (including many drugs). However, in the vast majority of these molecules, the piperazine ring is isolated (i.e. not fused to another ring) and is not substituted on any of its carbon atoms. A modular synthetic approach is described in which combinations of cyclic sulfamidate and hydroxy sulfonamide building blocks may be converted into piperazines and related 1,4-diazepine and 1,5-diazocane scaffolds. By variation of the combinations of building blocks used, it was possible to vary the ring size, substitution and configuration of the resulting heterocyclic scaffolds. The approach was exemplified in the synthesis of a range of heterocyclic scaffolds that, on decoration, would target lead-like chemical space. It was demonstrated that lead-like small molecules based on these scaffolds would likely complement those found in large compound collections. This journal is the Partner Organisations 2014.
- James, Thomas,Maclellan, Paul,Burslem, George M.,Simpson, Iain,Grant, J. Andrew,Warriner, Stuart,Sridharan, Visuvanathar,Nelson, Adam
-
supporting information
p. 2584 - 2591
(2014/04/17)
-
- Structural studies on bioactive compounds. 34.1 Design, synthesis, and biological evaluation of triazenyl-substituted pyrimethamine inhibitors of Pneumocystis carinii dihydrofolate reductase
-
The triazenyl-pyrimethamine derivative 3a (TAB), a potent and selective inhibitor of Pneumocystis carinii DHFR, was selected as the starting point for a lead optimization study. Molecular modeling studies, corroborated by a recent crystal structure determination of the ternary complex of P. carinii DHFR-NADPH bound to TAB, predicted that modifications to the acetoxy residue of the lead inhibitor could exploit binding opportunities in the vicinity of an active site pocket bounded by residues Ile33, Lys37, and Leu72. Substitutions in the benzyl moiety with electron-donating and electron-withdrawing groups were predicted to probe face-edge interactions with amino acid Phe69 unique to the P. carinii enzyme. New triazenes 10a-v and 12a-f were prepared by coupling the diazonium tetrafluoroborate salt 6b of aminopyrimethamine with substituted benzylamines or phenethylamines. The most potent of the new inhibitors against P. carinii DHFR was the naphthylmethyl-substituted triazene 10t (IC50: 0.053 μM), but a more substantial increase in potency against the rat liver DHFR led to a reduction in selectivity (ratio rat liver DHFR IC50/P. carinii DHFR IC50: 5.36) compared to the original lead structure 3a (ratio rat liver DHFR IC50/P. carinii DHFR IC50: 114).
- Chan,Laughton,Queener,Stevens
-
p. 2555 - 2564
(2007/10/03)
-
- Synthesis of β-lactams from acetic acids and imines induced by phenyl dichlorophosphate reagent
-
The development of a practical method for the preparation of vinylamino-β-lactams from Dane salts and Schiff bases is described. Among the reagents known to produce β-lactams from imines and acetic acids, only phenyl dichlorophosphate and 1-methyl-2-chloropyridinium iodide are suitable for the synthesis of vinylamino-β-lactams. Reaction of acetic acids with ethanolimine derivatives promoted by phenyl dichlorophosphate affords oxazolidines instead of β-lactams. Protection of the hydroxyl group as the trimethylsilyl ether in the starting Schiff bases provides a convenient route to the corresponding β-lactams instead of oxazolidines. Some observations on the scope of the method are made.
- Arrieta,Cossio,Palomo
-
p. 1703 - 1712
(2007/10/02)
-