257-97-6Relevant academic research and scientific papers
Triplet Dynamic Nuclear Polarization of Guest Molecules through Induced Fit in a Flexible Metal–Organic Framework**
Fujiwara, Saiya,Kimizuka, Nobuo,Matsumoto, Naoto,Nishimura, Koki,Tateishi, Kenichiro,Uesaka, Tomohiro,Yanai, Nobuhiro
supporting information, (2022/01/19)
Dynamic nuclear polarization utilizing photoexcited triplet electrons (triplet-DNP) has great potential for room-temperature hyperpolarization of nuclear spins. However, the polarization transfer to molecules of interest remains a challenge due to the fast spin relaxation and weak interaction with target molecules at room temperature in conventional host materials. Here, we demonstrate the first example of DNP of guest molecules in a porous material at around room temperature by utilizing the induced-fit-type structural transformation of a crystalline yet flexible metal–organic framework (MOF). In contrast to the usual hosts, 1H spin-lattice relaxation time becomes longer by accommodating a pharmaceutical model target 5-fluorouracil as the flexible MOF changes its structure upon guest accommodation to maximize the host–guest interactions. Combined with triplet-DNP and cross-polarization (CP), this system realizes an enhanced 19F NMR signal of guest target molecules.
Wavelength selective photoactivated autocatalytic oxidation of 5,12-dihydrobenzo[: B] phenazine and its application in metal-free synthesis
Bian, Lei,Feng, Xiaotong,Guo, Guangsheng,Ma, Jie,Pu, Qiaosheng,Wang, Xiayan,Wang, Yuanhang,Zhao, Lei,Zhao, Lizhi
, p. 9949 - 9954 (2020/03/23)
Photochemical stability of 5,12-dihydrobenzo[b]phenazine (DHBP) was investigated with LEDs with central emission wavelengths in a range of 365 to 595 nm. Photochemical conversion of DHBP to benzo[b]phenazine (BP) was observed with wavelengths upto 516 nm. Light of 490 and 516 nm is not absorbed by DHBP, but photoactivated autocatalytic oxidation of DHBP to BP with these wavelengths was confirmed. The reaction rate is in a range of 111-208 μg min-1 with these LEDs. The mechanism of the reaction was examined and the experimental results exclude the intermolecular interaction such as the F?rster resonance energy transfer, the intermolecular charge transfer, the photoinduced electron transfer and the formation of an exciplex. The formation of the reactive oxygen species was verified with electron paramagnetic resonance, which indicates its potential in the synthesis. When sunlight was used as the light source, the oxidation rate of 1 mg mL-1 DHBP was 393 μg min-1. Same autocatalytic oxidation was also observed on similar compounds and it can be used for producing metal-free organic substances for semiconductors.
Potential chemopreventive agents based on the structure of the lead compound 2-bromo-1-hydroxyphenazine, isolated from streptomyces species, strain CNS284
Conda-Sheridan, Martin,Marler, Laura,Park, Eun-Jung,Kondratyuk, Tamara P.,Jermihov, Katherine,Mesecar, Andrew D.,Pezzuto, John M.,Asolkar, Ratnakar N.,Fenical, William,Cushman, Mark
experimental part, p. 8688 - 8699 (2011/02/28)
The isolation of 2-bromo-1-hydroxyphenazine from a marine Streptomyces species, strain CNS284, and its activity against NF-κB, suggested that a short and flexible route for the synthesis of this metabolite and a variety of phenazine analogues should be developed. Numerous phenazines were subsequently prepared and evaluated as inducers of quinone reductase 1 (QR1) and inhibitors of quinone reductase 2 (QR2), NF-κB, and inducible nitric oxide synthase (iNOS). Several of the active phenazine derivatives displayed IC50 values vs QR1 induction and QR2 inhibition in the nanomolar range, suggesting that they may find utility as cancer chemopreventive agents.
Are N,N-dihydrodiazatetracene derivatives antiaromatic?
Miao, Shaobin,Brombosz, Scott M.,Schleyer, Paul V R.,Wu, Judy I.,Barlow, Stephen,Marder, Seth R.,Hardcastle, Kenneth I.,Bunz, Uwe H. F.
, p. 7339 - 7344 (2008/12/21)
The synthesis and X-ray characterization of two new dialkynylated diazatetracenes and the corresponding N,N-dihydrodiazatetracenes are reported. The dialkynylated heteroacenes are packed in a brick-wall motif that enforces significant overlap of their π-faces. Cyclic voltammetry indicates that the dehydrogenated forms are easily reduced to their radical anions in solution. The planarity of these species validates the discussion of their aromaticity. Nucleus Independent Chemical Shift (NICS) computations demonstrate that both of these 20 π and 24 π electron systems are aromatic. Both experimental and computational results suggest that the aromaticity of the dihydroheteroacenes is reduced.
Solid-phase synthesis of 1,2-benzophenazine and some fused imidazole derivatives
Zefirov,Sereda,Volkov,Tkachenko,Zyk
, p. 577 - 579 (2007/10/03)
The solid-phase synthesis of 1,2-benzophenazine and various N-methylbenzimidazoles using o-diaminoarenes is very promising and permits the synthesis of 1-methyl-4,5-[b]naphtho-1H-imidazole, which could not be obtained by the condensation of o-diaminoarenes with paraformaldehyde using the standard liquid-phase method. 1996 Plenum Publishing Corporation.
