利用甲酸、三氟醋酸、氟硼酸及硫酸作為質子型離子液體的陰離子，鹼則以六環的六氫哌啶系列 (piperidine)、嗎啉 (morpholine)系列及七環的六亞甲基亞胺 (azepane)三大類作為陽離子，在無溶劑的條件下以酸鹼中和概念得到質子型離子液體 (protic ionic liquids, PIL)。
使用核磁共振 (PGSE-NMR)的方法，測量離子液體的擴散係數，同時也測量離子液體之黏度、密度、導電度、極性與酸度，分別探討陰陽離子的結構對於離子液體的物理性質影響。結合導電度與擴散係數，經由Nernst-Einstein方程式計算各離子液體的解離程度，瞭解質子型離子液體的聚集現象。
結果顯示：(1) 離子液體的黏度、密度隨著溫度提升而下降，導電度與擴散係數隨著溫度提升而增加。(2) 在陰離子為HCOO-，改變陽離子環的大小(分別為六環Pip+與七環Azep+)，環效應造成七環Azep+離子液體的黏度大於六環Pip+，但導電度、密度、極性、擴散係數、解離程度小於六環Pip+，而比擴散係數隨著溫度上升增加的程度也同樣小於六環Pip+，然而酸度變化不顯著。(3) 在陰離子為HCOO-，進行六環陽離子氮上甲基或乙基取代(分別由Pip+ 、Mor+ 改為MePip+、EtPip+、4-MeMor+、4-EtMor+)，取代基效應導致陽離子為MePip+、EtPip+、4-MeMor+、4-EtMor+ 離子液體的黏度、導電度、解離程度大於未取代的陽離子Pip+、Mor+ 離子液體，比擴散係數隨溫度上升增加的程度同樣也大於未取代的陽離子Pip+、Mor+ 離子液體，而密度、擴散係數則小於未取代的陽離子Pip+、Mor+ 離子液體，極性與酸度略稍下降但不顯著。(4) 當陰離子為HCOO-，將陽離子由Pip+系列改為Mor+系列(Pip+系列包含Pip+、MePip+ 與EtPip+；Mor+系列包含Mor+、4-MeMor+ 與4-EtMor+)，陰、陽離子間偶極-偶極作用力增強導致Mor系列離子液體的黏度、密度、極性、酸度大於Pip+系列離子液體，而比擴散係數隨溫度上升增加的程度同樣也大於Pip+系列離子液體，但導電度及擴散係數小於Pip+系列離子液體；而當陰離子為BF -，陽離子分別為MePip+與4-MeMor+，同樣受到偶極偶極作用力的影響，[4-MeMor][BF4]其黏度等性質趨勢大於[MePip][BF4]，但導電度等性質趨勢則小於[MePip][BF4]，與上述陰離子為HCOO-的趨勢相同。(5) 當陰離子為HCOO-，陽離子分別為MePip+與4-MeMor+，在甲酸與鹼比例分別為1：1、2：1與4：1不同酸鹼比例的離子液體，隨著未解離甲酸的比例提高，黏度、酸度為[MePip][HCOO] ＞ [MePip][2HCOO]＞[MePip][4HCOO]，密度、導電度、極性、解離程度均為[MePip][4HCOO]＞[MePip][2HCOO]＞[MePip][HCOO]，但擴散係數為[MePip][4HCOO]＞[MePip][HCOO]＞[MePip][2HCOO]([MePip][2HCOO]與[4-MeMor][2HCOO]的擴散係數例外)。(6) 陽離子為MePip+，改變陰離子(HCOO-、TFA-、BF4-、HSO4-)，受到陰離子體積大小影響，陰離子擴散係數為HCOO-＞BF4-＞TFA-(陰離子HSO4-無法測量其擴散係)；陰離子的比擴散係數隨溫度增加的程度大小為BF-＞TFA-＞HCOO-。受到氫鍵作用力影響，黏度依序為[MePip][HSO4]＞[MePip][BF4]＞[MePip][TFA]＞[MePip][HCOO]。解離程度為[MePip][BF4]＞[MePip][TFA]＞[MePip][HCOO]。密度依序為[MePip][BF4]＞[MePip][HSO4]＞ [MePip][TFA]＞[MePip][HCOO]。受到黏度與離子形狀大小因素影響，導電度依序為[MePip][HCOO]＞[MePip][BF4]＞[MePip][TFA]＞ [MePip][HSO4]。提供陰離子所需的酸其酸性愈大，則極性、酸性愈大，極性依序為[MePip][HSO4]＞[MePip][BF4]＞[MePip][HCOO]＞[MePip][TFA] (但[MePip][TFA]為例外)；酸性為[MePip][HCOO] ＞[MePip][BF4] ([MePip][ HSO4]不溶於DCM溶劑，[MePip][TFA]為指示劑酸式吸收)。當陽離子為4-MeMor+、4-EtMor+，陰離子為HCOO-與 BF-，其趨勢同上。但在陽離子為Azep+，陰離子為HCOO-與TFA-，其導電度與解離程度為例外，導電度與解離程度：[ Azep][TFA]＞[Azep][HCOO]，其於趨勢同上。而不同陰離子的離子液體，黏度、酸性與極性隨著提供陰陽離子的酸與鹼pKa差值（△pKa）愈大而增加，導電度、擴散係數為下降。

Piperidinium-cation-based, morpholinium-cation-based and azepanium protic ionic liquids(PIL) were prepared through a simple neutralization reaction without any solvent and the Bronsted acids were formic acid, sulfuric acid, trifluoroacetic acid and hydrofluoroboric acid.
Nuclear Magnetic resonance techniques were applied to investigate the effect of varied temperature on ion diffusion coefficient by pulsed-gradient spin-echo NMR methods (PGSE-NMR) to understand the dynamics further and the properties affected by these cation and anion . The physical properties, such as viscosity, density, ionic conductivity, polarity, and Hammett acidity were also measured. We use Nernst-Einstein equation by combining the ionic conductivity and the diffusion coefficient of anion and cation to calculate the ion dissociation of PIL and to understand the aggregation phenomena between ions.
These results showed that (1)viscosity, density, ionic conductivity, and diffusion coefficient are temperature dependency. Viscosity and density of PIL will be lower with raising temperature, whereas ionic conductivity, diffusion coefficient will be larger. (2)When we changed the ring size of cation from Pip+ (six-membered ring) to Azep+ (seven-membered ring), the viscosity of [Azep][HCOO] will increase. However the ionic conductivity, density, polarity, diffusion coefficient, and the degree of ion dissociation will decrease. The increasement of specific diffusion coefficient also raises with increasing temperature. But the Hammett acidity scale remains the same.
(3)When the anion is HCOO-, we substitute the H atom with methyl or ethyl-group on the N atom of cation. The viscosity, ionic conductivity, the degree of ion dissociation of [MePip][HCOO], [EtPip][HCOO], [4-MeMor][HCOO], and [4-EtMor][HCOO] are larger than [Pip][HCOO], [Mor][HCOO]. And the increasement of specific diffusion coefficient are larger than [Pip][HCOO], [Mor][HCOO], too.But the density, and diffusion coefficient are smaller than [Pip][HCOO], [Mor][HCOO]. Whereas, the polarity, and Hammett acidity are smaller. (4)When the anion is HCOO-, we changed the cation from Pip+-based cation to Mor+-based cation. (It contains Pip+, MePip+, EtPip+ in Pip+-based cation, and it contains Mor+, 4-MeMor+, 4-EtMor+ in Mor +-based cation). Dipole-dipole interaction between anion and cation will increase the viscosity, density, and polarity, and Hammett acidity of Mor +-based ionic liquids, and the degree of specific diffusion coefficient increased are also larger than Mor+-based ionic liquids, but the ionic conductivity, and diffusion coefficient are smaller than Pip+-based ionic liquids . When the anion and cation are BF4-, MePip+, and 4-MeMor+, respectively, those properties mentioned above are still affected by dipole-dipole interaction between [MePip][BF4] and [4-MeMor][BF4]. And those trends are the same as [MePip][HCOO] and [4-MeMor][HCOO]. (5) When the anion is HCOO-, the cation are MePip+, and 4-MeMor+,we mixed the base (1-methylpiperidine or 4-methylmorpholine) and acid (formic acid) at various molar ratios from 1: 1, 1: 2, and 1: 4, respectively. Because those undissociated formic acid increased, the viscosity and Hammett acidity decrease in the order of [MePip][HCOO] > [MePip][2HCOO] >[MePip][4HCOO]. The density, polarity, ionic conductivity, and the degree of ion dissociation decrease in the order of [MePip][4HCOO] > [MePip][2HCOO] > [MePip][HCOO].However, the diffusion coefficient are in the order of [MePip][4HCOO] > [MePip][HCOO] > [MePip][2HCOO] with the exception of [MePip][2HCOO]. (6)While the cation is MePip+, we alter the anion by using of HCOO-, TFA-, BF4-, and HSO4-. The diffusion coefficient of anion is HCOO- > BF4- > TFA- because of the size of anion. (the diffusion coefficient of HSO4- is not obtained by NMR signal). The degree of specific diffusion coefficient with raising temperature follows the order of BF4->TFA- >HCOO-. The order of viscosity is [MePip][HSO4] > [MePip][BF4] > [MePip][TFA] > [MePip][HCOO]. The degree of ion dissociation is in the order of [MePip][BF4] > [MePip][TFA] > [MePip][HCOO]. And the density decreases in the order of [MePip][BF4] > [MePip][HSO4] > [MePip][TFA] > [MePip][HCOO]. The ionic conductivity is affected by both viscosity and the size, shape of ion. The conductivity decreases by [MePip][HCOO] > [MePip][BF4] > [MePip][TFA] > [MePip][HSO4]. The more acidic of acid providing for anion is , the higher of polarity, and acidity of PIL are. The polarity of PIL is in the order of [MePip][HSO4] > [MePip][BF4] > [MePip][HCOO] > [MePip][TFA] with the exception of [MePip][TFA]. The Hammett acidity scale follows the order of [MePip][HCOO] > [MePip][BF4] ([MePip][HSO4] is insoluble in dichloromethane). While the cation and anion are 4-MeMor+, 4-EtMor+, HCOO-, and BF4-, the trends are the same as mentioned above MePip+-based -cation PIL. But it is out of expection with [Azep][TFA], and [Azep][HCOO] in ionic conductivity and the degree of ion dissociation (the order is [Azep][TFA] > [Azep][HCOO]). When we changed the anion by fixing the cation, the viscosity, acidity, and polarity increase with the difference between acid and base providing for anion and cation, whereas the ionic conductivity and ion diffusion coefficient decrease.

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