Chapter 5- EXPERIMENTAL OBSERVATION, ANALYSIS AND...

106

Chapter 5- EXPERIMENTAL OBSERVATION, ANALYSIS AND DISCUSSION OF RESULTS OF FLUORESCENCE QUENCHING IN DIFFERENT SOLVENTS UNDER STEADY STATE

In this chapter, the experimental results obtained for steady state fluorescence

quenching of 4-(2,6-Dibromo-4-methyl-phenoxymethyl)-benzo [h] chromen-2-one in

Trichloroethylene, acetone and Tetrachloroethylene solvents, 6-Methoxy-4-p-

tolyoxymethyl-chromen-2-one in Trichloroethylene and Tetrachloroethylene solvents

and 4-(6,7-Dimethoxy-3,4-dihydro-isoquinoline-1-ylmethyl)-6-methyl-chromen-2-

one in acetone and Dimethylsulphoxide is given.

All these study is carried out at room temperature. In these systems studied Stern-

Volmer plots show positive deviation hence the experimental data were analyzed

using the modified Stern-Volmer equation (2.14) discussed in chapter two.

EXPERIHENTAL DETAILS:

Experimental arrangement and the procedure used for steady state measurements are

same as that explained in chapter three. The solutions were prepared keeping the

solute concentration fixed (5x10-5M/L) and the quencher concentration [Q] was varied

from 0.02 M/L to 0.1 M/L in each solvent. Fluorescence intensities IO without

quencher and I with different concentrations of quencher [Q] for all the three solutes

in respective solvents were measured corresponding to the peak position of the

emission spectrum at room temperature. There was no shift in the peak position of

the emission spectrum as a function of quencher concentration as shown in figure 5.1

for all three solutes.

RESULTS AND DISCUSSION:

The experimental data IO and I were given in tables 5.1 to 5.7 and the plots of IO/I

against Q were plotted in figures 5.2 to 5.4. From these figures it is observed that S-V

plots show positive deviation in all the cases. Equation (2.1) is only applicable to

linear S-V plots but for S-V plots with positive deviation suggests the quenching is

not purely collisional. This may be due to static quenching attributed to either the

107

ground state complex formation or sphere of action static quenching model. Thus

theory relating this is discussed.

Ground state complex formation:

Formation of complexes at ground state and formation of exciplex leading to non-

linearity in S-V plots can be analyzed using the extended Stern-Volmer equation

(2.13) and this can also be re-arranged as

((I0/I)-l]/[Q] =K 1+ K2 [Q]

Ground state complex formation can be analyzed only when there is shift in the peak

position in either emission spectra or absorption spectra. However in these three

solutes such shift in the peak position was not observed as it evident from the figure

5.1. Thus, theory relating to ground state complex formation is not discussed. This

shows that equation (2.13) is not applicable in our case for the analysis of the data

corresponding to the observed positive deviation in the Stern-Volmer plots. Thus, the

analysis of the experimental data for positive deviation in the Stern-Volmer plots are

made using sphere of action static quenching model described in chapter two.

Sphere of action static quenching model:

As already explained in chapter two, according to sphere of action static

quenching model, the deviation from the expected linear Stern-Volmer plot was

explained by the fact that only a certain fraction W (in the case of steady state

condition) of the excited state is actually quenched by the collisional mechanism. In

such a case, some molecules in the excited state, the fraction of which is (1-W) are de-

activated almost instantaneously after being formed because a quencher molecule

happens to be randomly positioned in the proximity at the time the solute molecules

are excited and interacts very strongly with them. Thus the fraction W decreases from

unity in contrast to the simple Stern-Volmer equation (2.1) where W=1. So, with the

introduction of an additional term W in the linear Stern-Volmer equation (2.1), this

equation gets modified to equation (2.14). To make this equation more meaningful,

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this has been re-written as equation (2.16). According to this equation the plots of [1-

(I/I0 )]/[Q] against (I/I0 ) becomes linear in the case of steady state measurements, the

slope of which is KSV and the intercept is (1-W)/[Q]. It may be noted that in solute of

such a deviation from the Stern-Volmer plot, the approximation made in equation

(2.16) is fully appropriate as the expansion inaccuracy is less than 4% over the

concentration range of the quencher used. Accordingly, equation (2.16) turns out to be

a more powerful equation for the analysis of strong quenching processes than the

usual Stern-Volmer equation (2.1). Figures 5.3 and 5.6 show the modified Stern-

Volmer plots of [1-(I/I0 )]/[Q] versus (I/I0 ) for all the three solutes with aniline as

quencher in respective solvents. As can readily be seen from these figures, the

intercepts are large in all the solvents but the intercept should strictly go to zero where

the linear condition W=1 is satisfied. Further, the Stern-Volmer or the steady state

quenching constants KSV are determined by least square fit method using equation

(2.16) for all the cases. Quenching rate parameter kq (= KSV /0 ) were determined

using experimental values of 0 of three solutes and the values of kq along with the

values of KSV are given in tables 5.8 to 5.10. The intercepts of the least square fit

lines in figures 5.3 to 5.6 are equal to (l-W)/[Q]. From the intercepts of plot [1-(I/I0

)]/[Q] versus (I/I0 ), the values of W were determined for each quencher

concentration. These values W were determined in order to find out the magnitude of

static quenching constant V and radius r of sphere of action, where the static or

instantaneous quenching occurs between the excited solute and quencher molecules.

Using the values of W, the static quenching constant V are determined by least square

fit method according to equation (2.18). Then, from these values of V, the radii ‘r’ of

sphere of action (or kinetic distance) were determined by 1east square fit method

using equation (2.20). The values of W, V and ‘r’ are given in tables 5.8 to 5.10 for

all the solutes in respective solvents.

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In order to compare the radius r of sphere of action with encounter distance R

i.e. the sum of the molecular radii of the interacting molecules, the radii of the solute

(RY) and the quencher (RQ) molecules were determined as suggested by Edward [4]

and are given at the bottom of tables 5.8 to 5.10. The encounter distances R (=RY +

RQ) estimated were, for 4-(2,6-Dibromo-4-methyl-phenoxymethyl)-benzo [h]

chromen-2-one, 7.121 for 6-Methoxy-4-p-tolyoxymethyl-chromen-2-one, 7.91 and

for 4-(6,7-Dimethoxy-3,4-dihydro-isoquinoline-1-ylmethyl)-6-methyl-chromen-2-

one, 7.033 angstrom unit respectively. The values of radius of sphere of action ‘r’ are

presented in tables 5.8 to 5.10 and these values of ‘r’ are approximately double the

encounter distance R. Such results were also obtained by others. [7, 20]. According to

Andre et al., [21] if the distance between the quencher molecule and excited molecule

lies between the encounter distance and the kinetic distance (radius of sphere of

action) the static effect takes place especially in the case of steady state experiments

irrespective of ground state complex formation provided the reactions are limited by

diffusion. So, in order to find out whether the reactions are diffusion limited the finite

sink approximation model described in chapter two for steady state experiments is

considered which helps to estimate independently the mutual diffusion coefficients

D, distance parameter R’ and activation energy controlled rate constant ka. To

determine these values, D, R’ and ka, the modified Stern-Volmer equation (2.48) of

finite sink approximation model is used. According to this equation it is necessary to

determine the values Ksv-1 (reciprocal KSV ) and [Q]1/3 . Where KSV = [ (IO/I) – 1]/[Q]

according to equation (2.1) and [Q] the quencher concentration from 0.02 to .1 M/L.

The values of KSV were determined at each quencher concentration in respective

solvents and the reciprocal of KSV are given in tables 5.15 to 5.17 along with

values of [Q]1/3. The plots of Ksv-1 against of [Q]1/3 according to equation (2.48) were

shown in figures 5.7 to 5.9. From these, it is observed that all plots are almost linear

with small deviation. Hence, linear dependence of Ksv-1 on one—third power of

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quencher concentration within the error limits associated with relative fluorescence

intensity measurements was confirmed. Then least square fit value of 푲풔풗푶 (S-V

constant at [Q]=0) were obtained from the intercept of the plots of 푲풔풗ퟏ against [Q]1/3

according to equation (2.48). Then, the mutual diffusion coefficients D were

determined from the slope of the equation (2.48) by least square fit method and values

of 푲풔풗푶 and D are given in tables 5.18 to 5.20. Using 푲풔풗

푶 and D, the distance

parameter R’ were determined according to equation (2.50) and are given in tables

5.18 5.20 and 5.22. Using the values of distance parameter R’ and encounter distance

R the activation energy controlled rate constant ka can be determined according to

equation (2.40). This value of ka can only be determined for R’ less than R [17].

Here, in all the three solutes it is found that the values of R’ are less than R however

for solute 4-(6,7-Dimethoxy-3,4-dihydro-isoquinoline-1-ylmethyl)-6-methyl-

chromen-2-one in acetone value R’ is greater than R. Thus, ka values have been

determined for the cases where R’ less than R and are shown in tables 5.18 5.20 and

5.22. According to Zeng et al.,[17] if ka is greater than kd (i.e equation 2. 4) then the

reactions are said to be diffusion limited which is true in our case in all the solutes

except in solute 4-(2,6-Dibromo-4-methyl-phenoxymethyl)-benzo [h] chromen-2-one,

in acetone. But, according to Joshi et al.,[22] the bimolecular reactions of

fluorescence quenching are said to be diffusion limited if the values of kq are greater

than 4πN’R’D. Thus the values 4πN’R’D were calculated using experimentally

determined values of R’and D which are given in tables 5.18 to 5.20. Then, these

values of 4πN’R’D are compared with quenching rate constant kq determined using

equation (2.16) and these values are in given in tables 5.18 5.20 and 5.22. From the

comparison, it is found that kq is greater than 4πN’R’D hence it may be concluded

that quenching reactions are diffusion limited.

From the foregoing discussions it is observed that the S-V plots show positive

deviation, and the range of kinetic distance r (i.e radius of sphere of action) almost the

111

double the encounter distance R and thus agree mostly with the reported values.

Further, from the magnitudes of kq and ka bimolecular quenching reactions in the

systems studied may be inferred as diffusion limited reactions. (except for 4-(2,6-

Dibromo-4-methyl-phenoxymethyl)-benzo [h] chromen-2-one, in acetone). In view of

these facts it may be concluded that static and dynamic (transient) quenching

phenomenon is playing role in all the systems studied.

112

Table 5.1: Fluorescence Intensity as function of Quencher concentration at fixed

solute concentration 5x10-5 M/L in TETRACHLOROETHYLENE

Molecule: 4-(2,6-Dibromo-4-methyl-phenoxymethyl)-benzo [h] chromen-2-one

Quencher: Aniline

Excitation wavelength: 360 nm

Emission wavelength: 430 nm

Quencher concentration (Q) (M/L) I Io/I I/Io (I0/I-1)/Q (1-I/Io)/Q

0.00 560.4 0.02 366.9 1.527 0.6570 26.10 17.148 0.04 265.2 2.113 0.4732 27.75 13.17 0.06 189.4 2.958 0.3380 32.50 11.032 0.08 148.4 3.78 0.2645 34.75 9.193 0.1 123.4 4.54 0.2202 35.40 7.79

Slope (Ksv) = 14.741 Intercept = 6.5838


solute concentration5x10-5 M/L in ACETONE


Quencher: Aniline




0.00 554.2 0.02 367.2 1.50 0.666 25 16.7 0.04 252.0 2.19 0.4566 29.75 13.52 0.06 186.5 2.97 0.3367 32.83 11.06 0.08 149.6 3.76 0.2702 33.75 9.12 0.1 125.6 4.41 0.2267 34.1 7.732


113


solute concentration 5x10-5 M/L in TRICHLOROETHYLENE


Quencher: Aniline




0.00 414.4 0.02 280.1 1.479 0.6802 23.95 15.98 0.04 182.4 2.271 0.4405 31.55 13.98 0.06 124.4 3.33 0.300 38.83 11.66 0.08 92.20 4.49 0.222 43.62 9.716 0.1 70.66 5.91 0.169 49.1 8.307


Table 5.4 : Fluorescence Intensity as function of Quencher concentration at fixed


Molecule: 6-Methoxy-4-p-tolyoxymethyl-chromen-2-one

Quencher: Aniline




0.00 53.59 0.02 46.37 1.152 0.8679 7.608 6.605 0.04 39.38 1.345 0.7430 8.6465 6.425 0.06 34.13 1.555 0.6415 9.3137 5.975 0.08 30.11 1.766 0.5660 9.5833 5.424 0.1 26.0 2.061 0.4851 10.611 5.148


114

Table 5.5 : Fluorescence Intensity as function of Quencher concentration at fixed



Quencher: Aniline




0.00 132.30 0.02 110.02 1.200 0.8333 10.00 8.330 0.04 91.19 1.450 0.6892 11.27 7.77 0.06 78.72 1.680 0.5931 11.34 6.75 0.08 69.21 1.911 0.5231 11.39 5.961 0.1 61.78 2.141 0.4669 11.41 5.340



solute concentration 5x10-5 M/L in ACETONE

4-(6,7-Dimethoxy-3,4-dihydro-isoquinoline-1-ylmethyl)-6-methyl-chromen-2-one

Quencher: Aniline





0.00 237.0 0.02 200 1.185 0.8438 6.5 7.805 0.04 163 1.453 .6896 11.25 7.75 0.06 130 1.823 0.5485 13.71 7.52 0.08 97 2.434 0.4098 18.04 7.30 0.1 69 3.43 0.2994 24.34 7.01

115


solute concentration 5x10-5 M/L in DIMETHYL SULPHOXIDE


Quencher: Aniline




0.00 252 0.02 230 1.09 0.9174 4.5 4.128 0.04 212 1.18 0.8412 4.7 3.968 0.06 194 1.298 0.7698 4.95 3.835 0.08 175 1.44 0.6944 5.5 3.819 0.1 157 1.605 0.6230 6.00 3.769


116

(a)

(b)

(c)

Fig 5.1 Fluorescence emission spectra of a) 4-(2,6-Dibromo-4-methyl-phenoxymethyl)-benzo [h] chromen-2-one b) 6-Methoxy-4-p-tolyoxymethyl-chromen-2-one c) 4-(6,7-Dimethoxy-3,4-dihydro-isoquinoline-1-ylmethyl)-6-methyl-chromen-2-on (C= 5 x 10-5 exc = 350 nm) in presence of aniline in solvents a) trichloroethylene b) dimethyl sulfoxide c) trichloroethylene at 270 C. Concentrations of aniline (in M/L)(1) 0.00 (2) 0.02 (3) 0.04 (4) 0.06 (5) 0.08 (6) 0.1

117

Fig: 5.2 Stern-Volmer plots of Io/I against Q 4-(2,6-Dibromo-4-methyl-

phenoxymethyl)-benzo [h] chromen-2-one with Aniline as quencher

0 . 0 2 0 . 0 4 0 . 0 6 0 . 0 8 0 . 1 00 . 0

0 . 5

1 . 0

1 . 5

2 . 0

T r i c h l o r o e t h y l e n e

I 0 / I

Q

0 . 0 0 0 . 0 2 0 . 0 4 0 . 0 6 0 . 0 8 0 . 1 00 . 0

0 . 2

0 . 4

0 . 6

0 . 8

1 . 0

1 . 2

1 . 4

1 . 6

1 . 8

2 . 0

2 . 2 t e t r a c h l o r o e t h y l e n e

I o/I

Q

Fig:5.3 Stern-Volmer plots of Io/I against Q for (6-Methoxy-4-p-tolyoxymethyl-

chromen-2-one) with Aniline as quench

118

0 . 0 2 0 . 0 4 0 . 0 6 0 . 0 8 0 . 1 00 . 00 . 10 . 20 . 30 . 40 . 50 . 60 . 70 . 80 . 91 . 01 . 11 . 21 . 31 . 41 . 51 . 6

D i m e t h y l S u l f o x i d e

I / I o

Q

0 . 0 2 0 . 0 4 0 . 0 6 0 . 0 8 0 . 1 01 . 0

1 . 5

2 . 0

2 . 5

3 . 0

3 . 5A c e t o n e

I / I o

Q

Fig:5.4 Stern-Volmer plots of Io/I against Q for 4-(6,7-Dimethoxy-3,4-dihydro-

isoquinoline-1-ylmethyl)- 6-methyl- chromen-2-one with Aniline as quench

119

Fig; 5.3 Modified Stern-Volmer plots of Io/I (1-I/Io)/Q against Io/I 4-(2,6-Dibromo-

4-methyl-phenoxymethyl)-benzo [h] chromen-2-one with Aniline as quencher

0 . 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 702468

1 01 21 41 61 8 A c e t o n e

(1-I o/I)

/Q

I / I o

0 . 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 702468

1 01 21 41 6

T r i c h l o r o e t h y l e n e

(1-I/

I o/Q)

I / I o

0 . 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 702468

1 01 21 41 61 8 t e t r a c h l o r o e t h y l e n e

(1-I/

I o)/Q

I / I o

120

0 . 0 0 . 2 0 . 4 0 . 6 0 . 8 1 . 00 . 0

0 . 5

1 . 0

1 . 5

2 . 0

2 . 5

3 . 0

3 . 5

4 . 0

4 . 5

5 . 0

5 . 5

6 . 0

6 . 5

7 . 0 T e t r a c h l o r o e t h y l e n e

(1-I/

I o)/Q

I / Io

Fig. 5.5: Modified Stern-Volmer plots of Io/I (1-I/Io)/Q against Io/I (6-Methoxy-4-p

tolyoxymethyl-chromen-2-one) with Aniline as quencher

Fig :5.6 Modified Stern-Volmer plots of (1-I/Io)/Q against I/Io for : 4-(6,7-

Dimethoxy-3,4-dihydro-isoquinoline-1-ylmethyl)-6-methyl chromen 2-one with

Aniline as quencher

0 . 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 94 . 04 . 24 . 44 . 64 . 85 . 05 . 25 . 45 . 65 . 8 T r i c h l o r o e t h y l e n e

(1-I/

I o)/Q

I / I o

121

Table 5.8 : The dynamic quenching constant Ksv, quenching rate parameter kq,

intercept (1-w)/Q, range of W, static quenching constant V and Kinetic distance r for

Different solvents in 5x10-5 M/L concentration of solute.


Quencher: Aniline



SOLVENT KSV

(m-1) kq x 10-10

(m-1s-1) Intercept Range of

W V

(mole-1 dm3) r (A0)

TRICHLORO ETHYLENE 14.7418 18.348 6.5838 0.4316-0.8684 11.54 16.38

ACETONE 20.021 18.367 3.791 0.6209-0.9241 4.962 19.64 TETRACHLORO

ETHYLENE 20.687 18.68 3.59 0.641-0.9282 4.621 12.23

Ry = 4.28A0 RQ = 2.84 A0 τ0 = 1.09 ns

Table 5.9 : The dynamic quenching constant Ksv, quenching rate parameter kq,

intercept (1-w)/Q, range of W, static quenching constant V and Kinetic distance r for

different solvents in 5x10-5 M/L concentration of solute.


Quencher: Aniline



SOLVENT KSV

(m-1) kq x 10-10


W V

(mole-1 dm3) r (A0)

TETRACHLOROETHYLENE 5.900 0.5175 3.2044 0.6759-0.9359 3.996 11.656

TRICHLORO ETHYLENE

8.3522 0.7326 1.6392 0.8636-0.9672 1.8204 8.9687

Ry = 5.07A0 RQ = 2.84 A0 τ0 = 01.140 ns

122

Table 5.10 : The dynamic quenching constant Ksv, quenching rate parameter

kq, intercept (1-w)/Q, range of W, static quenching constant V and Kinetic

distance r for different solvents in 5x10-5 M/L concentration of solute.


Quencher: Aniline



SOLVENT KSV

(m-1) kq x 10-10


W V

(mole-1 dm3) r (A0)

TRICHLORO ETHYLENE 4.255 5.129 2.18 0.5744-0.9148 5.803 13.199

ACETONE 1.326 1.598 6.746 0.3254-0.8652 12.08 16.85

DIMETHYL SULPHOXIDE 2.968 3.578 2.968 0.7032-0.9406 3.625 11.283

Ry = 4.193A0 RQ = 2.84 A0 τ0 = 8295ns

123


solute concentration 5x10-5 M/L in TETRACHLOROEHYLENE


Quencher: Aniline



Quencher concentration (Q) (M/L) I I0/I Q1/3 1

svK

0.00 560.4 0.02 366.9 1.527 0.2714 0.0383 0.04 265.2 2.113 0.34199 0.0360 0.06 189.4 2.958 0.13914 0.0307 0.08 148.4 3.78 0.4308 0.0287 0.1 123.4 4.54 0.4641 0.0282

Slope {(2N’)1/3/4N’D0} = -0.05764 Intercept (Ko

sv ) –1 =0.0539


solute concentration: 5x10-5 M/Lin ACETONE


Quencher: Aniline




svK

0.00 554.2 0.02 367.2 1.50 0.666 0.04 0.04 252.0 2.19 0.4566 0.0336 0.06 186.5 2.97 0.3367 0.0304 0.08 149.6 3.76 0.2702 0.0296 0.1 125.6 4.41 0.2267 0.0293

Slope {(2N’)1/3/4N’D0} = -0.05609 Intercept (Kosv ) –1 =0.05358

124




Quencher: Aniline




svK

0.00 414.4 0.02 280.1 1.479 0.2714 0.417 0.04 182.4 2.271 0.34199 0.314 0.06 124.4 3.33 0.13914 0.0257 0.08 92.20 4.49 0.4308 0.0229 0.1 70.66 5.91 0.4641 0.02040


sv ) –1 =0.0687




Quencher: Aniline



Quencher concentration (Q) (M/L) I Io/I Q1/3 1

svK

0.00 53.59 0.02 46.37 1.152 0.271 0.1314 0.04 39.38 1.345 0.342 0.1156 0.06 34.13 1.555 0.392 0.1073 0.08 30.11 1.766 0.431 0.1043 0.1 26.0 2.061 0.464 0.094

Slope {(2N’)1/3/4N’D0} = -0.16843 Intercept (Kosv ) –1 =0..1726

125




Quencher: Aniline




svK

0.00 132.30 - - 0.02 110.02 1.200 0.271 0.1000 0.04 91.19 1.450 0.342 0.0887 0.06 78.72 1.680 0.392 0.0881 0.08 69.21 1.911 0.431 0.0877 0.1 61.78 2.141 0.464 0.0876


sv ) –1 =0.0918


solute concentration 5x10-5 M/L in ACETONE


Quencher: Aniline




svK

0.00 237.0 0.02 200 1.185 0.2714 .1081 0.04 163 1.453 0.34199 .0888 0.06 130 1.823 0.13914 .072 0.08 97 2.434 0.4308 .0555 0.1 69 3.43 0.4641 .0416

Slope {(2N’)1/3/4N’D0} = -0..4836 Intercept (Kosv ) –1 =0.26441

126


solute concentration 5x10-5 M/L in DIMETHYLESULPHOXIDE


Quencher: Aniline




svK

0.00 252 0.02 230 1.09 0.2714 0.222 0.04 212 1.18 0.34199 0.2127 0.06 194 1.298 0.13914 0.2020 0.08 175 1.44 0.4308 0.1828 0.1 157 1.605 0.4641 0.1666

Slope {(2N’)1/3/4N’D0} = -0..2874 Intercept (Ko

sv ) –1 =0.3056

127

0 . 2 5 0 . 3 0 0 . 3 5 0 . 4 0 0 . 4 5 0 . 5 00 . 0 2 8

0 . 0 3 0

0 . 0 3 2

0 . 0 3 4

0 . 0 3 6

0 . 0 3 8

0 . 0 4 0 A c e t o n e

K-1

sv

Q 1 / 3

0 . 2 5 0 . 3 0 0 . 3 5 0 . 4 0 0 . 4 5 0 . 5 0

0 . 0 2 0

0 . 0 2 5

0 . 0 3 0

0 . 0 3 5

0 . 0 4 0

0 . 0 4 5t r i c h l o r o e t h y l e n e

K-1KS

V

Q 1 / 3

0 . 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 50 . 0 3 00 . 0 3 20 . 0 3 40 . 0 3 60 . 0 3 80 . 0 4 00 . 0 4 20 . 0 4 40 . 0 4 60 . 0 4 80 . 0 5 0 T e t r a c h l o r o e t h y l e n e

K-1

sv

Q 1 / 3

Fig; 5.7 Modified Stern-Volmer plots of 1svK against Q1/3 4-(2,6-Dibromo-4-methyl

phenoxymethyl)-benzo [h] chromen-2-one with Aniline as quencher

128

0 . 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5

0 . 0 8 7 5

0 . 0 8 8 0

0 . 0 8 8 5

0 . 0 8 9 0

0 . 0 8 9 5

0 . 0 9 0 0

0 . 0 9 0 5

0 . 0 9 1 0

0 . 0 9 1 5 t r i c h l o r o e t h y l e n e

K-1

sv

Q 1 / 3

0 . 2 5 0 . 3 0 0 . 3 5 0 . 4 0 0 . 4 5 0 . 5 00 . 0 9 0

0 . 0 9 5

0 . 1 0 0

0 . 1 0 5

0 . 1 1 0

0 . 1 1 5

0 . 1 2 0

0 . 1 2 5

0 . 1 3 0

0 . 1 3 5 T e t r a c h l r o e t h y l e n e

K-1sv

Q 1 / 3

a) Fig; 5.8 Modified Stern-Volmer plots of 1svK against Q1/3 4-(6,7-Dimethoxy-3,4-

dihydro-isoquinoline-1-ylmethyl)- 6-methyl- chromen-2-one with Aniline as

quencher

129

0 . 2 5 0 . 3 0 0 . 3 5 0 . 4 0 0 . 4 5 0 . 5 0

0 . 0 40 . 0 50 . 0 60 . 0 70 . 0 80 . 0 90 . 1 00 . 1 1

A c e t o n eK-1

sv

Q 1 / 3

0 . 2 5 0 . 3 0 0 . 3 5 0 . 4 0 0 . 4 5 0 . 5 00 . 1 60 . 1 70 . 1 80 . 1 90 . 2 00 . 2 10 . 2 20 . 2 3

d i m e t h y l e s u l p h o x i d e

K-1

sv

Q 1 / 3

b) Fig: 5.9 Modified Stern-Volmer plots of 1svK against Q1/3 for : 6-Methoxy-4-

p-tolyoxymethyl-chromen-2-one with Aniline as quencher

130

Table 5.18 : The values of K 0sv (Steady state quenching constant at [Q] = 0, Mutual

diffusion coefficient D, Distance parameter R’, 4N’DR’, Quenching rate parameter

kq and Activation energy controlled rate constant ka.


Quencher: Aniline



SOLVENT K 0sv

(M-1)

D x105 (cm2s-1)

R’ x 108 (Å)

4N’DR’ x 10-10

(M-1S-1)

kq x 10-10

(M-1S-1) ka x 10-10

(M-1S-1)

TRICHLORO ETHYLENE 14.168 2.6760 6.416 1.299 1.3524

13.848

ACETONE 18.348 3.329 6.680 1.6833 1.83678 32.390

TETRACHLORO ETHYLENE

18.258 3.448 6.416 1.6750 1.8978 8.942

R (Ry + RQ) =7.121Å

131

Table 5.19: The values of Mutual diffusion coefficients Da and Db, distance

parameter R’ and encounter distance R are given.


Quencher: Aniline



SOLVENT Da x105 (cm2s-1) Db x105 (cm2s-1) R’ x 108 (Å)

TRICHLORO ETHYLENE 3.8163 2.6760 6.416

ACETONE 5.2691 3.329 6.680


2.466 3.448 6.416

Da : Diffusion Coefficients determined from Stokes Einstein relation Db : Diffusion Coefficients determined from Finite Sink Model

Table 5.20: The values of K 0sv (Steady state quenching constant at [Q] = 0, Mutual


kq and Activation energy controlled rate constant ka

Molecule: 4- 6-Methoxy-4-p-tolyoxymethyl-chromen-2-one

Quencher: Aniline



SOLVENT K 0sv

(M-1)

D x105 (cm2s-1)

R’ x 108 (Å)

4N’DR’ x 10-10

(M-1S-1) kq x 10-10

(M-1S-1) ka x 10-10

(M-1S-1)

TETRACHLOROETHYLENE 5.7937 1.072 6.16 0.4998 0.5175 3.225

TRICHLORO ETHYLENE

10.893 0.31595 3.3916 0.0810 0.7326 1.079

R (Ry + RQ) =7. 91 Å

132

Table 5.21: The values of Mutual diffusion coefficients Da and Db, distance

parameter R’ and encounter distance R are given.

Molecule: 4- 6-Methoxy-4-p-tolyoxymethyl-chromen-2-one

Quencher: Aniline





2.3453 1.072 6.16

TRICHLORO ETHYLENE 3.6323 0.31595 3.3916

Da : Diffusion Coefficients determined from Stokes Einstein relation

Db : Diffusion Coefficients determined from Finite Sink Model

Table 5.22: The values of K 0sv (Steady state quenching constant at [Q] = 0, Mutual


kq and Activation energy controlled rate constant ka.


Quencher: Aniline



SOLVENT

K 0sv

(M-1)

D x105 (cm2s-1)

R’ x 108 (Å)

4N’DR’ x 10-10

(M-1S-1) kq x 10-10

(M-1S-1) ka x 10-10

(M-1S-1)

ACETONE 3.786 0.5131 11.7 0.1165 1.598 -----

DIMETHYL SULPHOXIDE 3.272 0.8635 6.035 0.2138 0.3578 9.932

R (Ry + RQ) =7. 033Å

133

Table 5.23 : The values of Mutual diffusion coefficients Da and Db, distance

parameter R’ and encounter distance R are given


Quencher: Aniline




ACETONE 5.2434 0.5131 11.7

DIMETHYL SULPHOXIDE 4.115 0.8635 6.035

Da : Diffusion Coefficients determined from Stokes Einstein relation

Db : Diffusion Coefficients determined from Finite Sink Model

134

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