Control of Crystalline-Amorphous Structures of Polyhedral Oligomeric Silsesquioxanes Containing Two Types of Ammonium Side-Chain Groups and Their Properties as Protic Ionic Liquids

Abstract

Polyhedral oligomeric silsesquioxanes (POSSs), Am-POSS(x,y), prepared by hydrolytic condensation, contains two types of ammonium side-chain groups, where the numbering of x and y represents the type of ammonium ions in the POSS structure, corresponding to primary (1), secondary (2), tertiary (3), and quaternary (4) ammonium ions. Mixtures of the two starting materials selected from organotrialkoxysilanes containing primary, secondary, and tertiary amines and a quaternary ammonium salt [(RO)3Si(CH2)3R′, R = CH3 or CH2CH3, R′ = NH2, NHCH3, N(CH3)2, and N(CH3)3Cl] were dissolved in dimethyl sulfoxide (DMSO). The hydrolytic condensation was performed in the presence of bis(trifluoromethansulfonyl)imide (HNTf2) and water. All Am-POSS(x,y) structures consisted of a cage-type octamer (T8-POSS), as confirmed by 29Si NMR spectrometry and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analyses indicated that Am-POSS(1,3), Am-POSS(1,4), and Am-POSS(2,4) had amorphous structures. These POSSs have two or three differences in the number of methyl groups between the two types of ammonium side-chains. Conversely, Am-POSS(1,2), Am-POSS(2,3), and Am-POSS(3,4) had crystalline structures. The difference in the number of methyl groups between the two types of ammonium side-chains in these POSSs is only one. Therefore, the crystalline-amorphous structure of Am-POSS(x,y) is controlled by the side-chain group combinations. Furthermore, Am-POSS(1,3), Am-POSS(1,4), and Am-POSS(2,4) are protic ionic liquids with relatively low flow temperatures.

A Kinetically Superior Rechargeable Zinc‐Air Battery Derived from Efficient Electroseparation of Zinc, Lead, and Copper in Concentrated Solutions

“…The [Zn(bet) 2 ][NTf 2 ] 2 looks like colorless and transparent glass that can be broken by hand (see the Supporting Information, Figure S1). There is a big difference of the PXRD patterns between [Zn(bet) 2 ][NTf 2 ] 2 and the pure [Hbet][NTf 2 ] and ZnO (Figure 1a), which shows the amorphous structure of solid [Zn(bet) 2 ][NTf 2 ] 2 [50] . Figure 1b shows the liquid‐phase 13 C NMR spectrum of [Zn(bet) 2 ][NTf 2 ] 2 , which showed no additional or absent signals compared to the pure IL [Hbet][NTf 2 ], [3] but the resonances were slightly shifted upfield.…”

“…All solutions are colorless except for sulfolane, which is a yellowish liquid. The fastest dissolution was observed in AN, which illustrates that highly polar organic solutions are favorable for the dissolution of [Zn(bet) 2 ][NTf 2 ] 2 [50] . Before we evaluated the electrochemical properties of the solution, we determined the IR and UV/Vis spectra of these six different electrolytes compare to the pure [Zn(bet) 2 ][NTf 2 ] 2 .…”

“…There is a big difference of the PXRD patterns between [Zn(bet) 2 ][NTf 2 ] 2 and the pure [Hbet][NTf 2 ] and ZnO (Figure 1a), which shows the amorphous structure of solid [Zn(bet) 2 ][NTf 2 ] 2 . [50] Figure 1b shows the liquid-phase 13 C NMR spectrum of [Zn(bet) 2 ][NTf 2 ] 2 , which showed no additional or absent signals compared to the pure IL [Hbet][NTf 2 ], [3] but the resonances were slightly shifted upfield. As in our previous study, [3,8] we explain this by the deprotonation of the carboxyl group and the formation of the complex [Zn(bet) 2 ] 2 + , which reduces the electron abstraction from the C atom and increases the shielding of the nuclei.…”

“…The fastest dissolution was observed in AN, which illustrates that highly polar organic solutions are favorable for the dissolution of [Zn(bet) 2 ][NTf 2 ] 2 . [50] Before we evaluated the electrochemical properties of the solution, we determined the IR and UV/Vis spectra of these six different electrolytes compare to the pure [Zn(bet) 2 ][NTf 2 ] 2 . Except DMF based electrolytes, the highlighted coordination of the betaine can be clearly seen by comparing the IR spectra of the pure [Zn(bet) 2 ][NTf 2 ] 2 and different electrolytes (Figure 1d; enlarged images in Figure S2).…”

Modulation of Properties by Ion Changing Based on Luminescent Ionic Salts Consisting of Spirobi(boron ketoiminate)

“…Two ligands with the spiro structures could play a critical role in lowering T m s by disturbing intermolecular interaction in the crystalline state. Moreover, symmetric structures of cations might contribute to lowering T m s, as observed in the nano-cluster-containing ionic liquids [ 49 , 50 ].…”