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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Photoswitching magnetic crossover in organic molecular systems
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Photoswitching magnetic crossover in organic molecular systems

机译：有机分子系统中的光开关磁性交叉

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摘要

We have theoretically designed efficient photomagnetic diradicals using both substituted and unsubstituted cyclophanediene (CPD) and dihydropyrenes (DHP) as spacers. Nitronyl nitroxide (NN), oxoverdazyl (o-VER), and tetrathiafulvalene (TTF) are chosen as monoradical centers. Molecular geometries have been optimized by the density functional method UB3LYP using the 6-311G(d,p) basis set. Final single point calculations have been done with the 6-311++G(d,p) basis. Absorption wavelengths have been estimated from time-dependent density functional treatment using restricted spin-polarized density functionals (RB3LYP) and 6-31G basis. Both the substituted and unsubstituted CPD species with mixed monoradical centers are found to be antiferromagnetically coupled. Diradicals with the same centers but with DHP coupler exhibit strong ferromagnetic coupling. Also, photoexcitations of the diradicals are generally red-shifted by only a few nanometers from those of the 15,16-dimethyl pyrenes. This indicates that on photoexcitation a consistent magnetic crossover from an antiferromagnetic to a ferromagnetic regime is possible. The accompanying change in magnetic exchange coupling constant ΔJ is very large, varying from 445 to 1003 cm~(-1). As far as organic molecular magnetism is concerned, this observation is entirely new and likely to be of technological significance.
机译：我们从理论上设计了有效的光磁双自由基，同时使用了取代的和未取代的环戊二烯（CPD）和二氢py烯（DHP）作为间隔基。选择一氧化氮亚硝基（NN），氧过氧二氮卓（o-VER）和四硫富瓦烯（TTF）作为单自由基中心。分子几何结构已通过使用6-311G（d，p）基集的密度泛函方法UB3LYP进行了优化。最终的单点计算已在6-311 ++ G（d，p）的基础上进行。使用受限的自旋极化密度泛函（RB3LYP）和6-31G，可以从时间依赖性密度泛函处理中估算出吸收波长。发现具有混合的单自由基中心的取代的和未取代的CPD物质都被反铁磁耦合。具有相同中心但带有DHP耦合器的双基自由基表现出强铁磁耦合。同样，双自由基的光激发通常与15，16-二甲基pyr的光激发仅红移几纳米。这表明在光激励下，从反铁磁到铁磁的稳定的磁交叉是可能的。伴随的磁交换耦合常数ΔJ的变化非常大，从445到1003 cm〜（-1）。就有机分子磁性而言，这一发现是全新的，可能具有技术意义。

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