1

Supporting Information for

Dynamically Wavelength-Tunable Random Lasers Based on Metal-

organic Framework Particles

Baoyuan Xu,a Zhenhua Gao,*a Yanhui Wei,b Yang Liu,a Xun Sun,a Weiguang

Zhang,a Xue Wang,a Zifei Wang,a Xiangeng Meng*a

a. School of Materials Science & Engineering, Qilu University of Technology (Shandong

Academy of Sciences), 3501 Daxue Road, Changqing District, Jinan 250353, Shandong

Province, China

b. College of Chemistry and Material Science, Shandong Agricultural University, Taian,

271018, Shandong, China

E-mail: gaozhenhua@qlu.edu.cn; mengxiangeng@gmail.com

Electronic Supplementary Material (ESI) for Nanoscale.This journal is © The Royal Society of Chemistry 2020

2

Table of Contents

1. Materials and experimental details.

1). Materials

2). Preparation of bio-MOF-100 particles

3). Characterizations

3. Figure S1. Molecular structure of bio-MOF-100.

4. Figure S2. X-ray powder diffraction patterns of simulated bio-MOF-100, bio-MOF-100

particles.

5. Figure S3. Histogram for the size distribution of the MOF particles.

6. Figure S4. Geometries of DASPI, LAD 722 and LDS 750 molecules.

3. Figure S5. Schematics of an ion-exchange process that is used to introduce the cationic

dye LDS 722 inside bio-MOF-100.

4. Figure S6. Digital photographs of bio-MOF-100 powder before and after introduction

of LDS 722 dye.

5. Figure S7 PL spectra of LDS722 and LDS722@bio-MOF-100 powders recorded under

excitation at 532 nm.

6. Figure S8. Normalized PL spectra of LDS 722 molecules in different solvents with

increasing polarity.

7. Table S1. PL decay of LDS 722@bio-MOF100 particles.

8. Figure S9. Temperature-dependent PL spectra of LDS 722@bio-MOF100 particles.

9. Figure S10. Threshold of LDS 722@bio-MOF100 random lasers measured at different

temperatures.

10. Figure S11. Lasing properties of DASPI@bio-MOF-100 random lasers.

11. Figure S12. Lasing properties of LDS 750@bio-MOF-100 random lasers.

3

Materials and experimental Section

Materials: Trans-4-[4-(dimethylamino)styryl]-1-methylpyridinium iodide (DASPI), 4-[4-

[4-(dimethylamino)phenyl]-1,3-butadienyl]-1-ethyl-pyridinium perchlorate (LDS722) and

2-[4-[4-(dimethylamino)phenyl]-1,3-butadienyl]-3-ethyl-naphtho[2,1-d]thiazolium

perchlorate (LDS750) were purchased from Sigma-Aldrich and used without further

purification. All the chemicals were used without further treatment.

Preparation: Three kinds of dissolved stock solutions, adenine (2.5 ml, 0.13 mmol) in

DMF, Zinc acetate dehydrate (5 ml, 0.25 mmol) in DMF, Biphenyldicarboxylic acid (2.5

ml, 0.25 mmol) in DMF, were prepared by ultrasonication. Then, these three kinds of

stock solutions were poured into a 20 ml vial with the late addition of 2.5 ml of DMF, 1ml

of methanol and 0.25 ml of deionized water. The vial was capped and heated at 85 ℃ for

24 h and then cooled down to room temperature. The resultant product was rinsed with

DMF three times and then dried in vacuum conditions, giving the Bio-MOF-100

crystalline powders. Crystals of Bio-MOF-100 were immersed in a solution of LDS 722 in

DMF (0.45 mM) at 60 ℃ for 24 h to load LDS 722 into Bio-MOF-100. The resultant

products were washed by DMF several times until there is no detectable PL signal in the

supernatant. After being dried at 60 ℃ for 5 h, the crystals of LDS 722@Bio-MOF-100

were obtained. The preparation of DASPI@Bio-MOF-100 and LDS 750@Bio-MOF-100

undergoes the same steps mentioned above. The density of different dye molecules in the

MOF systems were estimated according to the Beer-Lambert law. The dye molecule

cations can be released from the MOF systems by exchanging cations with Li+ and then

comparing with the reference sample.1 The calculated concentrations are 37.4, 27.1 and

18.8 mmol·L-1, respectively for the DASPI@MOF, LDS722@MOF and LDS750@MOF

particles.

Characterizations: The morphology of the bio-MOF-100 particles was examined through

scanning electron microscopy (Hitachi Regulus8220). The optical absorption and PL

spectra were measured on a UV-visible spectrometer (SHIMADZU UV-3600 Plus) and a

fluorescence spectrometer (EDINBURGH FLS1000), respectively. The transient PL

decay spectra were measured on Edinburgh FLS1000 photoluminescence spectrometer

4

(Edinburgh Instruments, UK) equipped with a supercontinuum white light laser (Superk

EXTREME, 2-80 MHz) as the light source, and the excitation wavelength was set as 532

nm (19.5 MHz). The decay curves detected at different wavelengths of 650, 700 and 800

nm within the PL band of LDS722@MOF, respectively. The dye concentration in sample

of LDS722@MOF is 27.1 mmol·L-1. A focused picosecond pulsed laser beam from an

optical parametric generator (EKSPLA, PG-401) was employed to locally excite the

dye@bio-MOF-100 composite particles and the spatially resolved spectra were recorded

with a monochrometer (Princeton Instruments, SP-2500) connected with an CCD

(Princeton Instruments, PIXIS 256). XRD measurements...

Calculations: The calculations were performed with Gaussian software on the basis of

density functional theory (DFT) by using the ɷB97XD functional and 6-311G (d,p) basis

set.

5

ZnNOC

Figure S1. Molecular structure of bio-MOF-100. The structure of bio-MOF-100 consists of

inorganic (Zn) and organic building blocks (adeninate (ad) and biphenyldicarboxylate

(BPDC) linkers).2 Eight Zn2+ cations are interconnected with four adeninates, two μ-oxo

groups and six monodentate BPDCs, forming the molecular structure formulated as

Zn8(ad)4(BPDC)6O2∙4Me2NH2. The framework has a net 4-charge per formular unit, resulting

in the anionic microenvironment of bio-MOF-100.

6

10 20 30

10 20 302θ (degree)

Simulated bio-MOF-100

Bio-MOF-100 particles

Inte

nsity

(a.u

.)

Fig. S2. X-ray powder diffraction patterns of bio-MOF-100: simulation (black curve) and

experimental (red curve). The experimental results are well consistent with the simulated

ones, suggesting that phase-pure bio-MOF-100 was obtained.

7

0.4 0.8 1.2

5

10

15

20

25

0.4 0.8 1.2Size (μm)

5

10

15

20

25

Freq

uenc

y co

unt

Fig. S3. Histogram for the size distribution of the MOF particles. The average size of the

particles is determined to be about 0.8 ± 0.2 μm.

8

Figure S4. Geometries of DASPI, LAD 722 and LDS 750 molecules that are optimized on

the ɷB97XD/6-311G (d, p) level of theory. The lateral dimensions are determined to be 0.48,

0.50 and 0.60 nm for DASPI, LDS 722 and LDS 750 molecules, respectively.

9

LDS 722 dye

N

N

Figure S5. Schematics of an ion-exchange process that is used to introduce the cationic dye

LDS 722 inside bio-MOF-100. The internal pores of bio-MOF-100 contain a large amount of

Me2NH2+ cations, thus allowing for facile incorporation of cationic dyes via strong ionic

interaction.

10

LDS 722 dye

Figure S6. Digital photographs of bio-MOF-100 powders before and after introduction of

LDS 722 dye. Owing to the strong ionic interaction, the MOFs exhibit an obvious color

change from the original colorless to the final purple particles after the ion exchange,

indicating that the LDS 722 laser dye were encapsulated into the bio-MOF-100 pores.

11

650 700 750 800

650 800700Wavelength(nm)

Inte

nsity

(a.u

.)

LDS722@bio-mof-100LDS722 powder

x30

750

Figure S7. PL spectra of LDS722 and LDS722@bio-MOF-100 powders excited at 532 nm.

The much stronger PL signal from LDS722 in bio-MOF-100 than bare LDS722 powders

indicates the occurrence of an efficient monomer emission in the confined system. The

restricted ICT dyes display strong red emission compared with that of LDS722 powder,

indicating that the ICT dye molecules confined in the pores of MOFs have restricted

intramolecular torsional motion and restrained π-π interactions,3 providing a good candidate

for high-performance random lasing.

12

600 700 800

n-butanolAcetoneDMF

Wavelength (nm)

DMSO

600 700 800

Inte

nsity

(a.u

.)

Figure S8. Normalized PL spectra of LDS 722 molecules in different solvents with increasing

polarity (DMSO>DMF>Acetone>n-butanol). When the solvent polarity increased gradually

from low-polarity n-butanol to high-polarity DMSO, the LDS 722 solution exhibits a large

red-shift of 25 nm. This large solvatochromic shift, which is commonly consistent with the

large dipole moment of the ICT state, indicates that the LDS 722 molecules possess a strong

ICT state characteristic.4

13

Table S1. PL decay of LDS 722@bio-MOF100 particles at different wavelength.

t1(ns)

w1 t2(ns)

w2 χ2

650 nm

700 nm

800 nm

2.150.65 0.67

0.72 0.58 2.21 0.42 0.99

0.99

0.76 0.46 2.23 0.54 0.98

0.33

The PL decay curve of LDS 722@bio-MOF100 particles was best fitted with two exponential

components, which indicates that the luminescence is originated from two excited states,

namely LE state and TICT state.

14

680 720 760 800

680 720 760Wavelength(nm)

Inte

nsity

(a.u

.)

298 K323 K

375 K423 K

Figure S9. Temperature-dependent PL spectra of LDS 722@bio-MOF100 particles. The

temperature-dependent PL spectra prove the feasibility of tuning the gain region in the MOF

pellets, which can be utilized to build wavelength tunable random lasers.

15

300 330 360 390 420

0.5

1.0

1.5

2.0

300 330 360 390 420

0.5

1.0

1.5

2.0

Temperature (K)

Thre

shol

d(m

Jcm

-2)

Figure S10. Threshold of the LDS 722@bio-MOF100 random lasers evaluated at different

temperatures. The high temperature causes the additional nonradiative losses of LDS 722

dyes. Accordingly, the lasing threshold increases monotonically with temperature.

16

600 620 640 660

0

10000

20000

30000

40000

50000

600 630 660

600Wavelength(nm)

Inte

nsity

(a.u

.)

640620

630600 660Wavelength(nm)

0.2 0.4 0.6 0.8

0

20

40

60

0.2 0.80.4 0.6

0

20

40

60

Pump fluence(mJ cm2)

Inte

nsity

(a.u

.)

FWH

M(n

m)

Ith=0.46 mJ cm-2

660

Pump fluence

0.21 mJ cm-2

0.54 mJ cm-2

0.68 mJ cm-2

0.84 mJ cm-2

a b

Figure S11. (a) Evolution of the emission spectral profile with the pump fluence for

DASPI@bio-MOF-100 random lasers. Inset: Emission spectra recorded below (black) and

above (red) the pump threshold. (b) Dependence of the emission intensity (red) and the

spectral linewidth (blue) on the pump fluence.

17

0.6 0.9 1.2 1.5

0

30

60

90

720 750 780 810

730 770 810

730Wavelength(nm)

Inte

nsity

(a.u

.)

810770

720 750 780 810Wavelength(nm)

0.6

0

Pump fluence(mJ cm2)

Inte

nsity

(a.u

.)

FWH

M(n

m)

0.9 1.2 1.5

60

30

90Pump fluence

0.58 mJ cm-2

1.12 mJ cm-2

1.37 mJ cm-2

1.60 mJ cm-2

Ith=0.96 mJ cm-2

a b

Figure S12. (a) Evolution of the emission spectral profile with the pump fluence for

LDS750@bio-MOF-100 random lasers. Inset: Emission spectra recorded below (black) and

above (red) the pump threshold. (b) Dependence of the emission intensity (red) and the

spectral linewidth (blue) on the pump fluence.

18

References:

1. Y. Liu, H. Dong, K. Wang, Z. Gao, C. Zhang, X. Liu, Y. S. Zhao, F. Hu, ACS Appl. Mater.

Interfaces 2018, 10, 35455-35461.

2. J. An, O. K. Farha, J. T. Hupp, E. Pohl, J. I. Yeh, N. L. Rosi, Nat. Commun. 2012, 3, 604.

3. Y. Wei, H. Dong, C. Wei, W. Zhang, Y. Yan, Y. S. Zhao, Adv. Mater. 2016, 28, 7424-

7429.

4. W. Li, D. Liu, F. Shen, D. Ma, Z. Wang, T. Feng, Y. Xu, B. Yang, Y. Ma, Adv. Funct.

Mater. 2012, 22, 2797-2803.