Pt/Pd–Ethynyl Bond Containing Fluorescent Molecular Architectures as Sensors for Nitroaromatics - Molecular Self-Assembly: Advances and Applications - page 286

3 -1

( K ) was determined to be (Fig. 9.21) 19.6 × 10 M in CH Cl -DMF

SV 2 2

(4:1).

Figure 9.21 Fluorescence quenching of 17 by TNT (left) and Stern-

Volmer plot (right).

The fluorescence intensity in the solution state of both 21 and

23 underwent quenching upon gradual addition of TNT (2,4,6-

trinitrotoluene) solution. When a 1.5 × 10

in
DMF was titrated with a TNT solution in methanol, the fluorescence
intensity gradually decayed as shown in Fig. 9.22. The mechanism
of fluorescence quenching could be due to the formation of charge-
transfer complex between the excited state of

-6

M solution of 21

π

-electron-rich cage

21 and an electron-deficient oxidizer TNT. The Stern-Volmer plot

(Fig. 9.22) gave a quenching constant of

-1

K = 173.3

±

5.46 M . The

SV

high quenching constant in case of 21 was probably due the presence

of electron-donating -CH , which makes the cage a better host for

3

electron-deficient TNT.

Figure 9.22 Fluorescence quenching of 21 by TNT (left) and Stern-

Volmer plot (right).