ABSTRACT
The syntheses of high-spin organic polymers have been a daunting task due to the highly reactive nature of organic radicals, especially when they are ferromagnetically coupled. In this paper, we report our approach to obtain high-spin organic polymers, in which a reasonably stable fluorenyl radical was employed as the primary radical unit, and s-triazine serves as the connector that facilitates ferromagnetic coupling between them. Initially, the diamagnetic polymer precursor was synthesized by cyclotrimerization of a cyano-monomer. Subsequently, the high-spin polymers were obtained by oxidizing corresponding anionic polymers using O2 (6) or I2 (7). The temperature-dependent magnetic moments, and field-dependent magnetization data obtained from SQUID measurements revealed ferromagnetic couplings between primary radical units, with coupling J = 7.5 cm-1 and 38.6 cm-1. The percentages of primary unit in the radical form are 29%, and 47% for 6 and 7, respectively. Notably, this marks the first reported instance of a high-spin fluorenyl radical polymer exhibiting ferromagnetic coupling.
ABSTRACT
Objective:To explore the effects of caffeine on the prevention of Alzheimer's disease (AD).Methods:Use Ethanol as a solvent to extract the caffeine in tea and then injecting 5％ D-galactose saline solution 1ml/d/kg to establish aging model mice.Divide mice randomly into experimental group (high-dose/low-dosecaffeine),positive control group,negative control group,and normal con-trol group (NS) and injecting appropriate drugs for consecutive four weeks.Test superoxyde dismutase (SOD) and malondialdehvde (MDA) periodically.Take mice's hippocampus and use Western blotting to detect the expression of brain derived neurotrophic factor (BDNF) and extracellular signal-regulated kinasesl/2 (p-ERK1/2).Results:The expression of BDNF and p-ERK1/2,negative control group is less than low-dose experimental group and positive control group (P＜0.01);The p-ERK1/2 expression of injecting D-galactose mice was significantly lower than normal group,negative control group compared weth the normal group,the differencd was significant (P＜0.05).The level of SOD in model group was significantly lower than that in normal control group,high,low dose caffeine group and positive control group (P＜0.01),but the level of MDA is opposite.Conclusions:Caffeine can delay aging process by increasing the level of SOD in aging mice,and enhancing the expression of BDNF and P-ERK1/2.Caffeine does a lot to prevent AD.