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The relative chemical shifts (△δ) △δwere put forward to investigate the microscopic structure of 1-ethyl-3-methyl-imidazolium tetrafluoroborate (EmimBF4) during the dilution process with water.The concentration-dependent △δ(C2)H-(C4)H,△δ(C2)H-(C5)H and △δ(C4)H-(C5)H were analyzed.The results reveal that the variations of the microscopic structures of three aromatic protons are inconsistent.The strength of the H-bond between water and three aromatic protons follows the order:(C2)H···O > (C4)H···O > (C5)H···O.The concentration-dependent △δ(C6)H-(C7)H and △δ(C6)H-(C8)H indicate the formation of the H-bonds of (Calkyl)H···O is impossible,and more water is located around (C6)H than around (C7)H or (C8)H.The concentration-dependent △δ(C2)H-(C4)H and △δ(C2)H-(C5)H both increase rapidly when xwater > 0.9 or so,suggesting the ionic pairs of EmimBF4 are dissociated rapidly.The turning points of concentration-dependent △δ(C2)H-(C4)H and △δ(C2)H-(C5)H indicate that some physical properties of the EmimBF4/water mixtures also change at the corresponding concentration point.The microscopic structures of EmimBF4 in water could be clearly detected by the relative chemical shifts.
The relative chemical shifts (Δδ) Δδwere put forward to investigate the microscopic structure of 1-ethyl-3-methyl-imidazolium tetrafluoroborate (EmimBF4) during the dilution process with water.The concentration- dependentΔδ (C2) H- C4) H, Δδ (C2) H- (C5) H and Δδ (C4) H- (C5) H were analyzed.The results reveal that the variations of the microscopic structures of three aromatic protons are inconsistent. The strength of the H-bond between water and three aromatic protons follows the order: (C2) H ··· O (C4) H ··· O (C5) H ····. The concentration- H (C7) H and Δδ (C6) H- (C8) H indicate the formation of the H-bonds of (Calkyl) H ··· is impossible, and more water is located around (C7) H or (C8) H.The concentration-dependentΔδ (C2) H- (C4) H and Δδ (C2) H- (C5) H both increase rapidly when xwater> 0.9 or so, suggesting the ionic pairs of EmimBF4 are dissociated rapidly.The turning points of concentration-dependentΔδ (C2) H- (C4) H andΔδ (C2) H- (C5) H i ndicate that some physical properties of the EmimBF4 / water mixtures also change at the corresponding concentration point. The microscopic structures of EmimBF4 in water could be clearly detected by the relative chemical shifts.