Fernandes Ana M, Coutinho João A P, Marrucho Isabel M
QOPNA, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
J Mass Spectrom. 2009 Jan;44(1):144-50. doi: 10.1002/jms.1484.
Positive singly charged ionic liquid aggregates (C(n)mim)(m+1)(BF(4))(m) (mim = 3-methylimidazolium; n = 2, 4, 8 and 10) and (C(4)mim)(m+1)(A)(m) (A = Cl(-), BF(4) (-), PF(6) (-), CF(3)SO(3) (-) and (CF(3)SO(2))(2)N(-)) were investigated by electrospray ionisation mass spectrometry and energy-variable collision induced dissociation. The electrospray ionisation mass spectra (ESI-MS) showed the formation of an aggregate with extra stability for m = 4 for all the ionic liquids with the exception of [C(4)mim][CF(3)SO(3)]. ESI-MS-MS and breakdown curves of aggregate ions showed that their dissociation occurred by loss of neutral species ([C(n)mim][A])(a) with a >or= 1. Variable-energy collision induced dissociation of each aggregate from m = 1 to m = 8 for all the ionic liquids studied enabled the determination of E(cm, 1/2) values, whose variation with m showed that the monomers were always kinetically much more stable than the larger aggregates, independently of the nature of cation and anion. The centre-of-mass energy values correlate well with literature data on ionic volumes and interaction and hydrogen bond energies.
通过电喷雾电离质谱法和能量可变碰撞诱导解离对带正电荷的单电荷离子液体聚集体[（C（n）mim）（m + 1）（BF（4））（m）]+（mim = 3 - 甲基咪唑鎓；n = 2、4、8和10）以及[（C（4）mim）（m + 1）（A）（m）]+（A = Cl-、BF（4）-、PF（6）-、CF（3）SO（3）-和（CF（3）SO（2））（2）N-）进行了研究。电喷雾电离质谱（ESI - MS）表明，除了[C（4）mim][CF（3）SO（3）]之外，对于所有离子液体，当m = 4时会形成具有额外稳定性的聚集体。聚集体离子的ESI - MS - MS和分解曲线表明，它们通过损失中性物种（[C（n）mim][A]）（a）（a≥1）而发生解离。对所研究的所有离子液体从m = 1到m = 8的每个聚集体进行可变能量碰撞诱导解离，从而能够确定E（cm，1/2）值，其随m的变化表明，单体在动力学上总是比更大的聚集体稳定得多，这与阳离子和阴离子的性质无关。质心能量值与关于离子体积、相互作用和氢键能的文献数据相关性良好。
