Yao Wenzhi, Kelley Steven P, Rogers Robin D, Vaid Thomas P
Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487, USA.
Phys Chem Chem Phys. 2015 Jun 7;17(21):14107-14. doi: 10.1039/c5cp01172h. Epub 2015 May 11.
Two different room-temperature liquid systems were investigated, both of which conduct a DC electrical current without decomposition or net chemical transformation. DC electrical conductivity is possible in both cases because of the presence of two different oxidation states of a redox-active species. One system is a 1 : 1 molar mixture of n-butylferrocene (BuFc) and its cation bis(trifluoromethane)sulfonimide salt, [BuFc(+)][NTf2(-)], while the other is a 1 : 1 molar mixture of TEMPO and its cation bis(trifluoromethane)sulfonimide salt, [TEMPO(+)][NTf2(-)]. The TEMPO-[TEMPO(+)][NTf2(-)] system is notable in that it is an electrically conducting liquid in which the conductivity originates from an organic molecule in two different oxidation states, with no metals present. Single-crystal X-ray diffraction of [TEMPO(+)][NTf2(-)] revealed a complex structure with structurally different cation-anion interactions for cis- and trans [NTf2(-)] conformers. The electron transfer self-exchange rate constant for BuFc/BuFc(+) in CD3CN was determined by (1)H NMR spectroscopy to be 5.4 × 10(6) M(-1) s(-1). The rate constant allowed calculation of an estimated electrical conductivity of 7.6 × 10(-5)Ω(-1) cm(-1) for BuFc-[BuFc(+)][NTf2(-)], twice the measured value of 3.8 × 10(-5)Ω(-1) cm(-1). Similarly, a previously reported self-exchange rate constant for TEMPO/TEMPO(+) in CH3CN led to an estimated conductivity of 1.3 × 10(-4)Ω(-1) cm(-1) for TEMPO-[TEMPO(+)][NTf2(-)], a factor of about 3 higher than the measured value of 4.3 × 10(-5)Ω(-1) cm(-1).
研究了两种不同的室温液体体系，它们都能传导直流电，且不会发生分解或净化学转化。在这两种情况下都能实现直流电导率，这是因为存在具有两种不同氧化态的氧化还原活性物种。一种体系是正丁基二茂铁（BuFc）与其阳离子双（三氟甲烷）磺酰亚胺盐[BuFc(+)][NTf2(-)]的1:1摩尔混合物，而另一种是2,2,6,6-四甲基哌啶氮氧化物（TEMPO）与其阳离子双（三氟甲烷）磺酰亚胺盐[TEMPO(+)][NTf2(-)]的1:1摩尔混合物。TEMPO-[TEMPO(+)][NTf2(-)]体系值得注意的是，它是一种导电液体，其电导率源自处于两种不同氧化态的有机分子，且不存在金属。[TEMPO(+)][NTf2(-)]的单晶X射线衍射揭示了一种复杂结构，其中顺式和反式[NTf2(-)]构象异构体具有结构不同的阳离子-阴离子相互作用。通过(1)H核磁共振光谱法测定，CD3CN中BuFc/BuFc(+)的电子转移自交换速率常数为5.4×10(6) M(-1) s(-1)。该速率常数使得能够计算出BuFc-[BuFc(+)][NTf2(-)]的估计电导率为7.6×10(-5)Ω(-1) cm(-1)，是测量值3.8×10(-5)Ω(-1) cm(-1)的两倍。同样，先前报道的CH3CN中TEMPO/TEMPO(+)的自交换速率常数导致TEMPO-[TEMPO(+)][NTf2(-)]的估计电导率为1.3×10(-4)Ω(-1) cm(-1)，约为测量值4.3×10(-5)Ω(-1) cm(-1)的3倍。
