Synthesis and Conductive Performance of Temperature Control-type Ionic Liquid Based on Keggin Polyoxometalate

Abstract

A temperature control-type ionic liquid based on ternary Keggin polyoxometalate, [PyPS] 4 PW 11 VO 40 , has been synthesized and characterized. It is solid state at room tempareture and it shows a phase transformation below 100 • C. The results indicate that this compound possesses layered type structure. Its conductive performance is investigated. Its conductivity is as high as 6.20 × 10 −3 S · cm −1 at 120 • C.Heteropoly acids (HPAs) and their polyoxometalate salts (POMs), a fascinating class of inorganic metal-oxygen cluster compounds, have been known for almost two centuries. A large amount of basic researches have emerged in various areas ranging from structural diversity to applications including catalysis, medicine, biology and materials science because of their novel chemical, structural and electronic properties. [1][2][3][4] Lots of the researches in materials science have been reported that these compounds have good conductivity either in solution or as solid. 5-7 Unfortunately, HPAs suffer from high sensitivity to atmospheric moisture, diffusional problems, relatively weak thermal stability and continuous leakage during cell operation. In order to broaden their application, the design and synthesis of HPA derivatives are of great interest. Among these HPA derivatives, a new family of polyoxometalate-based ionic liquids (POM-ILs) that are based on ionic liquids and HPAs have been explored. Ionic liquids (ILs) have attracted special interests owing to their negligible volatility, excellent thermal stability, remarkable solubility, electrical conductivity and the variety of structures available. 8,9 Rickert et al. have synthesized and characterized a series of POM-ILs based on polyoxometalates and ionic liquids. 10 Giannelis has reported a new kind of POM-IL prepared by PW 12 O 40 3− anion and bulky PEG-containing quaternary ammonium cation. This HPA derivative has higher conductivity than that of its solid analog, which has been found promising for electrolytes. 11 A variety of these POM-ILs constructed from classical Keggin-, Wells-Dawson-and Anderson-type heteropolyanions. 12,13 However, most of the anions they used are binary HPAs, the application of vanadium-substituted ternary HPAs as anions is scarce. So we chose monovanadium-substituted ternary HPA (H 4 PW 11 VO 40 ) and 1-(3-sulfonic group) propyl-3-methyl pyridine (PyPS) to synthesize a new POM-IL. In this paper, we have studied the conductive performance of this POM-IL. ExperimentalSyntheses of POM-IL.-PyPS was synthesized according to the literature. 14 H 4 PW 11 VO 40 was synthesized according to the procedure described in our previous report. 15 The presynthesized PyPS and HPA (H 4 PW 11 VO 40 ), was taken in 4:1 mole ratio to give one mole of [PyPS] 4 PW 11 VO 40 . PyPS was added to an ethanol solution of HPA (0.2 g · mL −1 ), and then the mixture was stirred for 12 h at room temperature. The orange-yellow product was washed with ethanol and dried in vacuum at room temperature to give the final one.Instruments and reagents.-FTIR spectrum w...

The synthesis and electrical properties of hybrid gel electrolytes derived from Keggin-type heteropoly acids and 3-(pyridin-1-ium-1-yl)propane-1-sulfonate (PyPs)

“…Based on the higher activation energy (>0.20 eV), it can be assumed that the proton conduction in these types of hybrids appears to be following a vehicle mechanism. 34 Cyclic voltammetry analysis was used to understand the electrochemical stability window (ESW) of PyPs-H 3 PWMo at room temperature, and is shown along with electrical conductivity comparison of currently studied hybrids with other known promising proton conductors including Naon 22,35,36 (Fig. 8).…”

Synthesis and characterization of metal-substituted tetraalkylphosphonium polyoxometalate ionic liquids

“…37 Reactions between polyoxometalates and other organic cations, to this date, have provided several types of compounds, including a number of liquid crystal phases, 40,41 but only a handful of materials that can be described as truly ionic liquids. 38,39,42 From these, and besides the above mentioned compounds, 11,37 IL-materials are known with functionalized guanidinium, 43 pyridine derivatives, 44 quaternary 42,45,46 and functionalized alkylammonium, 47 and alkylphosphonium cations. 45,46,[48][49][50][51][52][53] Several polyoxometalate (POM) anions were used, ranging from the dianionic Lindquist anion, 48,50 [W 6 O 19 ] 2À , to the highly charged lantanodecatungstate anions [LnW 10 O 36 ] nÀ (Ln = Eu, Tb and n = 9; Ln = Ce and n = 8).…”

“…45,46,[48][49][50][51][52][53] Several polyoxometalate (POM) anions were used, ranging from the dianionic Lindquist anion, 48,50 [W 6 O 19 ] 2À , to the highly charged lantanodecatungstate anions [LnW 10 O 36 ] nÀ (Ln = Eu, Tb and n = 9; Ln = Ce and n = 8). 51,52 However, research has mainly been centred on Keggin-type structures, such as the parent [PW 12 O 40 ] 3À , 11,43,48,50 or the mixed addenda anions [PM 11 VO 40 ] 4À (M = Mo, W) 44,49,53 and [PW 9 V 3 O 40 ] 6À . 46 Studies involving transitionmetal substituted Keggin-anions have remained scarce, with only two recent reports addressing the study of the interaction of the anions [SiW 11 O 39 M(H 2 O)] nÀ (M = Fe III and n = 5; M = Cu II and n = 6) with tetraalkylammonium, 42,45 and trihexyl(tetradecyl)phosphonium 45 cations, published during the progress of this work.…”