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Table 1 1 H NMR limiting chemical shifts (∆ δ lim ) for protons in IAA, 2-NAA, and 2,4-D

From: pH-controlled release of auxin plant hormones from cucurbit[7]uril macrocycle

1Ha pH
  1.0 3.0 5.0 7.0 9.5 12.0
IAA       
 a 0.0055 0.0049 −0.0003 −0.0012 0.0002 −0.0018
 b 0.0056 0.0058 0.0024 0.0002 0.0035 0.0024
 c 0.0042 0.0045 0.0012 0.0002 0.0012 0.0006
 d 0.0054 0.0057 0.0021 0.0005 0.0024 0.0010
 e 0.0026 0.0031 −0.0005 −0.0016 0.0000 −0.0009
 f 0.0014 0.0021 0.0004 0.0004 0.0022 0.0010
2-NAA       
 g 0.0182 0.0003 −0.0008 0.0015 0.0024 −0.0002
 h 0.0136 −0.0014 −0.0014 0.0005 0.0010 −0.0096
 i 0.0151 −0.0018 0.0000 0.0012 0.0025 −0.0002
 l 0.0071 −0.0046 −0.0017 0.0002 0.0008 −0.0015
 m −0.0035 −0.0065 −0.0011 −0.0007 0.0000 −0.0014
 n ND ND ND ND ND ND
2,4-D       
 o 0.0036 0.0020 0.0007 0.0006 0.0011 0.0004
 p 0.0073 0.0010 0.0005 0.0004 0.0006 0.0003
 q 0.0039 0.0020 0.0004 0.0000 0.0007 −0.0004
 r ND 0.0008 0.0001 0.0002 0.0003 −0.0009
  1. aAuxin protons in IAA, 2-NAA and 2,4-D, upon addition of one equivalent of CB[7], and at different solution pH. Letters indicate positions of protons on auxins structure as reported in Figure 2. ND, not determined because it was masked by other signals. The ∆δlim values were calculated as δfree guestδbound guest.