英语翻译For studying the nature of the interaction between senso

英语翻译
For studying the nature of the interaction between sensor
QB and Zn2+/Cd2+,1H NMR titrations were also carried out
(Figure 5 and Table S2,Supporting Information).Upon
interaction with Zn2+ and Cd2+,the protons of the methoxy
CH3 experienced significant upfield shifts (ΔδZn ) 0.97; ΔδCd
) 0.41 ppm),indicating that the oxygen atom of the methoxy
group strongly bonded with Zn2+/Cd2+.The protons at ortho
position of pyridines downfield shifted from 8.49 to 8.66
(Zn2+) and to 8.80 (Cd2+),respectively,by N-metal coordination
effect.Meanwhile,similar upfield shifts were also
observed for the proton at the 3-position of quinoline,
suggesting the direct interaction between quinoline platform
and metal ions.When 4 equiv of Cd2+ was further introduced
into the ZnQB solution,compare Figure 5d with 5b,
chemical shifts of all protons changed significantly and are
almost identical with these of the sole CdQB (Figure 5c).
The finding indicates that QB has higher affinity for Cd2+
than for Zn2+,which consequently incurs the ion displacement
process.
In conclusion,we have developed a novel fluorescent
sensor,QB.It shows a ratiometric response to Zn2+ based
on both CHEF and ICT mechanisms but a CHEF response
to Cd2+.Moreover,we show that the central ion of ZnQB
can be displaced by Cd2+,resulting in another ratiometric
sensing signal output.Thus,QB can be a dual mode Cd2+-
selective sensor via the CHEF mechanism and ratiometric
displacement approach.