21035-59-6Relevant articles and documents
Design and synthesis of a highly sensitive off-on fluorescent chemosensor for zinc ions utilizing internal charge transfer
Hanaoka, Kenjiro,Muramatsu, Yasuaki,Urano, Yasuteru,Terai, Takuya,Nagano, Tetsuo
, p. 568 - 572 (2010)
Fluorescence imaging is a powerful tool for the visualization of biological molecules in living cells, tissue slices, and whole bodies, and is important for elucidating biological phenomena. Furthermore, zinc (Zn2+) is the second most abundant heavy metal ion in the human body after iron, and detection of chelatable Zn2+ in biological studies has attracted much attention. Herein, we present a novel, highly sensitive off-on fluorescent chemosensor for Zn2+ by using the internal charge transfer (ICT) mechanism. The rationale of our approach to highly sensitive sensor molecules is as follows. If fluorescence can be completely quenched in the absence of Zn2+, chemosensors would offer a better signal-to-noise ratio. However, it is difficult to quench the fluorescence completely before Zn 2+ binding, and most sensor molecules still show very weak fluorescence in the absence of Zn2+. But even though the sensor shows a weak fluorescence in the absence of Zn2+, this fluorescence can be further suppressed by selecting an excitation wavelength that is barely absorbed by the Zn2+-free sensor molecule. Focusing on careful control of ICT within the 4-amino-1,8-naphthalimide dye platform, we designed and synthesized a new chemosensor (1) that shows a pronounced fluorescence enhancement with a blueshift in the absorption spectrum upon addition of Zn 2+. The usefulness of 1 for monitoring Zn2+ changes was confirmed in living HeLa cells. There have been several reports on 4-amino-1,8-naphthalimide-based fluorescent sensor molecules. However, 1 is the first Zn2+-sensitive off-on fluorescent sensor molecule that employs the ICT mechanism; most off-on sensor molecules for Zn2+ employ the photoinduced electron transfer (PeT) mechanism.
4-Aminoquinoline Antimalarials Containing a Benzylmethylpyridylmethylamine Group Are Active against Drug Resistant Plasmodium falciparum and Exhibit Oral Activity in Mice
Joshi, Mukesh C.,Okombo, John,Nsumiwa, Samkele,Ndove, Jeffrey,Taylor, Dale,Wiesner, Lubbe,Hunter, Roger,Chibale, Kelly,Egan, Timothy J.
, p. 10245 - 10256 (2018/01/10)
Emergence of drug resistant Plasmodium falciparum including artemisinin-tolerant parasites highlights the need for new antimalarials. We have previously shown that dibemequines, 4-amino-7-chloroquinolines with dibenzylmethylamine (dibemethin) side chains, are efficacious. In this study, analogues in which the terminal phenyl group of the dibemethin was replaced with a 2-pyridyl group and in which the 4-amino-7-chloroquinoline was either maintained or replaced with a 4-aminoquinoline-7-carbonitrile were synthesized in an effort to improve druglikeness. These compounds exhibited significantly improved solubility and decreased lipophilicity and were potent against chloroquine-sensitive (NF54) and -resistant (Dd2 and 7G8) P. falciparum strains with 5/6 having IC50 100 nM against the NF54 strain. All inhibited both β-hematin (synthetic hemozoin) formation and hemozoin formation in the parasite. Parasitemia was reduced by over 90% in P. berghei infected mice in 3/6 derivatives following oral dosing at 4 × 30 mg/kg, with microsomal metabolic stability data suggesting that this could be attributed to highly active metabolites.
Amidation of unactivated ester derivatives mediated by trifluoroethanol
McPherson, Christopher G.,Caldwell, Nicola,Jamieson, Craig,Simpson, Iain,Watson, Allan J. B.
, p. 3507 - 3518 (2017/04/26)
A catalytic amidation protocol mediated by 2,2,2-trifluoroethanol has been developed, facilitating the condensation of unactivated esters and amines, furnishing both secondary and tertiary amides. The complete scope and limitations of the method are described, along with modified conditions for challenging substrates such as acyclic secondary amines and chiral esters with retention of chiral integrity.
