Chemical and Biological Technologies in Agriculture

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

¹H^a	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

^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 ∆δ_lim values were calculated as δ_{free guest} – δ_{bound guest}.

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