1

Unique Effects of the Chain Lengths and Anions of

Tetraalkylammonium Salts on Quenching Pyrene

Excimer

<Supporting Information>

Hyun-Sook Jang1, Jing Zhao

2, Yu Lei

3, Mu-Ping Nieh

*1, 3

1. Polymer program, Institute of Materials Science, University of Connecticut, Storrs, CT, 06279,

USA

2. Department of Chemistry, University of Connecticut, Storrs, CT, 06269, USA

3. Department of Chemical & Biomolecular Engineering, University of Connecticut, Storrs, CT

06279, USA

4. Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06279, USA

Corresponding author

Mu-Ping Nieh, PhD

Telephone: 860-486-8708

mu-ping.nieh@ims.uconn.edu

2

Table S1 illustrates the values of Iexc/Imon and I1/I3 as a function of Py concentrations in acetone.

The fact that Iexc/Imon increases and I1/I3 decreases with increased Py concentration in all samples

in Table 2 (similar to the result shown in Fig. 2), indicates that the formation of the Py excimer

has no significant dependence of salts. The critical Py concentration is found higher (~ 0.1 M) in

the case of Py/THAPF6 solution than the other solutions, possibly due to the increased size of

salt, resulting in reduced mobility of Py.

Table S1. The Iexc/Imon and I1/I3 as a function of Py concentration in various Py/salt solutions.

3

Previously it has been reported that the excimer fluorescencce of the high-T prepared ternary

PS/Py/TBAPF6 thin film (having high excimer emission) can be quenched after being annealed

at 100 oC for 1 hour

1. The change of Py excimer configuration is presumably attributed from the

high mobility of Py as it is associated with PS matrix above the glass transition point. The same

approach is taken to test the high-T (100 °C) prepared binary Py/TBAPF6 system, which also

reveals a high excimer emission. Fig. S4 shows the fluorescence emission spectra of the high-T

prepared thin film before and after being annealed at 100 °C for 1 h. No significant change in Py

excimer fluorescence intensity was observed after high-T annealing, indicating no thermal effect

Figure S1. The fluorescence emission spectra of Py/ TBAPF6 film (black) prepared at

room-T and after being annealed under (a) acetone and (b) THF vapor generated by 1

mL of the solvent in the closed system at 95 °C (red) for 20mins.

Figure S2. The fluorescence emission spectra of freshly prepared high-T (100 °C)

Py/TBAPF6 film and after being annealed at 100 °C for 1 h. No significant change in

Py excimer fluorescence intensity was observed after high-T annealing, indicating that

no thermal effect on the Py excimers in the solid state.

4

on the Py excimers in the solid state. This result implies that the enhanced flexibility of Py

provided PS (> TG) is a key parameter to quench Py excimer.

The topology of Py and Py/salt films was examined by SEM to correlate an aggregation of Py

and it fluorescence response of Iexc in Fig.S5. Note that a significant difference of Iexc/Imon was

observed in Py/TBAPF6 films prepared by high-T and room-T, respectively in Fig.3. Also, salts

structures provided a different polar environment to the Py as shown Fig. 3. (i.e., room-T

prepared films of Py/ TBABF6 and Py/TBABF4 hydrophilic; Py/THAPF6 hydrophobic)

However, no clear difference was observed in the films made of Py and different salts as well as

by different preparation methods, suggesting us that there is little or non- correlation between

topology and formation of Py excimer in the film.

(a) Py_HT (b) Py /TBAPF6_RT

(c) Py/TBAPF6_HT (d) Py/TBABF

4_RT

(e) Py/THAPF6_RT

Figure S3 The SEM images of films (a) High-T

prepared Py (b) Room-T prepared Py/TBAPF6

(c)

High-T prepared Py/TBAPF6 (d) Room-T prepared

Py/TBABF4 (e) Room-T prepared Py/THAPF

6

5

Table S2. The lattice parameters of pyrene and TBAPF6 as well as the theoretical values of 1/d2

from XRD compared with the experimental result of the new peak yielding 0.014 Å-2

.

1

𝑑2=

ℎ2

𝑎2 +𝑘2

𝑏2 ∙ sin2 𝛽 +𝑙2

𝑐2

1 cos2 𝛽

Miller index for Pyrene2

Miller inde for TBAPF6

3

6

Fig S4 shows the XRD results of films (i.e. TEAPF6, THAPF6, and TBACl and its combination

with Py).

Figure S4. (a) The XRD spectra of different films (a) Py (black), TEAPB6(green) and room-T prepared Py/

TEAPF6 (blue)

6 9 12 15 18 21 24 27 30

Py_

HT

2 (degree)

TE

AP

F6

Py

TE

AP

F6

8.30

7.63 5.48 4.08 3.87 3.33

6.70 6.37

5.76

4.78

3.66

8.38

7.6 3

5.75

5.91

6.33

4.76

4.63 4.38

3.82 3.70

7

6 9 12 15 18 21 24 27 30

Py_

RT

2 (degree)

TH

AP

F6

Py

THA

PF

6

8.30

7.63 5.48 4.08 3.87 3.33

13.4

6.84 4.54

13.4

8.28

7.58

6.80 4.54

4.17

Figure S4.(b) The XRD spectra of different films (a) Py (black), THAPF6(green) and room-T prepared Py/

THAPF6 (blue)

8

Figure S4.(c) The XRD spectra of different films (a) Py (black), TBACl6(green) and room-T prepared Py/

TBACl (blue)

6 9 12 15 18 21 24 27 30

Py_

RT

2 (degree)

TB

AC

l

Py

TB

AC

l

0.83

7.63 5.48 4.08 3.87 3.33

9.98

8.40

8.98

4.13

11.30

8.43 7.99

4.23 6.93

3.97 3.77

9

Figure S4.(d) The XRD spectra of different films (a) Py (black), TBABF4(green) and room-T prepared Py/

TBABF4 (blue)

6 9 12 15 18 21 24 27 30

Py_

RT

2 (degree)

TB

AB

F4

Py

TB

AB

F4

0.83

0.763 0.548 0.408 0.387 0.333

13.0

11.94

9.76

9.0

8.05

3.42

4.25

4.07 4.51

5.06 5.94 7.06

06

9.75

8.94

8.09

7.61 0.693

5.68 4.71

4.17

4.05

3.88

10

The lifetime of excimer in Py/salt solutions was also studied to provide the insight to the

effect of the salts in this study on the formation of Py excimer. Fig. S5 shows practically the

same decay for all the cases, a confirmation of marginal effects of cation or anion structure on

the Py excimer quenching mechanism.

Figure S5. Fluorescence lifetime of solution (A) Py/TBA acetate (black), Py/TEAPF6 (red),

Py/THAPF6 (blue) , Py/TBABF4 (marine), Py/TBANO3 (pink), Py (dark green), and Py/TBAPF6

(dark blue).

The double-exponential and combinational decay functions [as shown in Eqs. (S1) and (S2)]

were used to best fit the data of excimer lifetime obtained from high-T prepared Py/TBAPF6 (or

pure Py) films and room-T prepared Py/TBAPF6 film, respectively. In the double-exponential

decay, two relaxation modes are assumed having the populations of A1 and A2, and the relaxation

times of 1 and 2, respectively. The excitation laser pulse came in at time to. It should be noted

that in the case of combinational decay function (used for the room-T prepared Py/TBAPF6 film)

A1 and A2 are kept unchanged and only a prefactor B is used to account for the population of the

same decay mechanism presented by the high-T prepared Py/TBAPF6 residue. The lifetime of

11

the new single-exponential decay constant, ’1 and the prefactor, A3 (presenting its population) as

well as B and to are obtained through best fitting the experimental data of the room-T prepared

Py/TBAPF6 film using Eq (S2).

( )

(S1)

( )

(

) (S2)

The best fitting parameters in the cases are summarized in Table S3.

Table S3. The best fitting parameters for double-exponential and combinational decay functions to describe the

excimer lifetimes of Py, high-T prepared Py/TBAPF6 and room-T prepared Py/TBAPF6 films.

(1) Double-exponential decay function

to (ns) A1 1(ns) 2 (ns) Py film 38.4 0.964 11.9 0.046 31.8 HT, Py/TBAPF6

film 38.0 0.987 12.3 0.036 41.6

(2) Combinational decay function

to (ns) A3 '1(ns) B RT, Py/TBAPF6 film 37.9 1.00 8.4 0.00

12

References

1. Jang, H.-S.; Wang, Y.; Lei, Y.; Nieh, M.-P., Controllable Formation of Pyrene (C16H10) Excimers in Polystyrene/Tetrabutylammonium Hexafluorophosphate Films through Solvent Vapor and Temperature Annealing. J. Phys. Chem. C. 2012, 117, 1428-1435. 2. Madelung, O.; Rössler, U.; Schulz, M. In Ternary Compounds, Organic Semiconductors, "Pyrene, C16H10 Crystal Structure, Lattice Parameters, Phase Transitions, Density, Melting Point." Eds. Springer Berlin Heidelberg: 2000; Chapter 1356, pp 1-3. 3. Schodel, F.; Lerner, H.-W.; Bolte, M., Tetra-n-Butylammonium Hexafluorophosphate. Acta Crystallogr. Sect. E. 2004, 60, o1680-o1681.