In aqueous solution, Zn2+ and Cd2+ in 100% CH3CN lead to
Blue shift emission with maximum wavelength variation
From 48 1 to 430 and 432 nm respectively (supporting information,
Numbers S4, S5); However, the addition of Zn2+ and Cd2+
Ztr in 100% DMSO leads to red-shift emission.
The maximum wavelength varies from 472 to 5 12 and 532 nm,
Respectively (supporting information, Figures S6 and S7). this
Figure 1. Effect of pH on fluorescence of ZTRS in acetonitrile/water (50:50, v/v). Excitation wavelength: 360 nm. [ZTRS]) 10 μm(a)pH
4.7- 12.8. Illustration: the functional relationship between fluorescence intensity at 483 nm and pH; (b) The pH value is 4.7- 1.8. Illustration: Ratio fluorescence changes with pH value.
Figure 2. (a) The fluorescence spectrum (50∶50) of 10 micron ztr in the presence of various metal ions in aqueous solution (CH3CN/0.5 M HEPES (pH 7.4)).
Excited at 360 nm. (b) Fluorescence spectra of ZTRS in the presence of different concentrations of Zn2+. The illustration shows the working diagram from the evaluation.
The fluorescence with a total concentration of 65438 00μ m.. The addition of other HTM ions leads to blue shift of emission.
In CH3CN and DMSO (supporting information, figure
S8、S9)。 However, the small blue shift of the absorption maximum
ZTRS in CH3CN, DMSO and aqueous solution
Add Zn2+ and Cd2+ (supporting information, figure
S 10-S 15) means that it will not cause red-shift emission.
Deprotonation of NH group of amide, because
Deprotonation of NH group conjugated with 1, 8- naphthalimide
It will lead to a red shift in the absorption spectrum. 18h, 25a These
Spectral data show that ZTRS binds Zn2+ and Cd2+
Different tautomeric forms depend on solvents and metals.
Ions (Scheme 3); Zn2+ and Cd2+ in ZTRS complex
Amide tautomers in CH3CN and imidic acid tautomers in CH3CN.
DMSO is dominant. However, other HTM ions are bound to
Amide tautomers in CH3CN and DMSO.
Further evidence of tautomers of amide and imino acid
The binding mode (scheme 3) was provided by 1H NMR titration.
ZTRS experiment of Zn2+ and Cd2+ in CD3CN (support
Information, figure S 16, S 17) and DMSO-d6 (support
Information, figure S 18, S 19), 2D·NOESY of Zhongtian company.
/Zn2+ (1: 1 complex) in CD3CN (fig. 3, supporting information,
Fig. S20, S2 1) and DMSO-d6 (fig. 3, S22-23),
And the infrared spectra of ZTRS/Zn2+ (1: 1 complex) in CH3CN.
(support information, figure S24) and DMSO (support
Information, figure S25). For reference, bind properties
The interaction between ZTF and Zn2+ was studied by 1H NMR.
And infrared spectrum.
Contrary to the fluorescence response of ZTRS and metal ions in aqueous solution, in 100% CH3CN, Cd2 ++ and Zn2 ++ produce blue-shift emission, and the maximum wavelength changes from 48 1 to 430 and 432nm, respectively (supporting Figures S4 and S5). However, adding Cd2 ++ and Zn2 ++ to ZTRS in 100% DMSO will cause the maximum wavelength to change from 472nm to 5 12nm and 532nm, respectively (Figures S6 and S7 support this information). Adding other HTM ions will lead to blue shift of emission in CH3CN and DMSO (supporting information in Figures S8 and S9). However, when Cd2 ++ and Zn2 ++ were added, the absorption spectrum of ZTRS in CH3CN, DMSO and aqueous solution slightly shifted blue (supporting information in Figure S 10-S 15), which indicated that the red-shift emission was not the result of deprotonation of amide NH group, because it was associated with 1 8 naphthalimide *. These spectral data tell us that ZTRS binds to Cd2 ++ and Zn2 ++ in different tautomeric forms according to solvents and metal ions (Scheme 3). ZTRS is mainly complexed with Cd2+ and Zn2+ in amide tautomer in CH3CN and with Cd2+ and Zn2+ in imino tautomer in DMSO. However, in CH3CN and DMSO, other ions combine with amide tautomers.
Using CD3CN (supporting figures S 16 and S 17) and DMSO-d6 (supporting figures S 18 and S65438), the tautomeric binding mode of amide and imino acid was obtained from ZTRS titration experiment with hydrogen nuclear magnetic resonance (1H NMR) (Scheme 3 In S20/S2 1, ZTRS/Zn2+( 1: 1 complex) and DMSO-d6 (fig. 3, S22, S23), as well as the two-dimensional nuclear magnetic resonance spectrum (2D NOESY) of CH3CN (fig. S24) and DMSO. As a reference, the binding properties of ZTF with Zn2+ were studied by 1H NMR and IR spectra.