1

Fluorescent metal-organic frameworks based on mixed

organic ligands: new candidates for highly sensitive

detection of TNPDong Wang,a,b Zhiyong Hu,b Shasha Xu,b Dandan Li,*a Qiong Zhang,b Wen Ma,b

Hongping Zhou,b Jieying Wu,*b Yupeng Tian*b

a Institute of Physics Science and Information Technology, Anhui University, Hefei 230601, China

b Department of Chemistry, Key Laboratory of Functional Inorganic Materials Chemistry of Anhui

Province, Anhui University, Hefei 230601, P. R. China

* Corresponding author: chemlidd@163.com, yptian@ahu.edu.cn

Electronic Supplementary Material (ESI) for Dalton Transactions.This journal is © The Royal Society of Chemistry 2019

mailto:yptian@ahu.edu.cn

2

Content

Experiment section5

Materials and apparatus5

Computational details5

Synthesis of ligands5

Scheme S1. Synthetic routes for ligands6

Synthesis of 4,4'-(phenylazanediyl)dibenzoic acid (H2L1)6

Synthesis of 4,4'-(4-phenylpyridine-2,6-diyl)dibenzoic acid(H2L2)6

Synthesis of 2,6-BIP7

Results and discussion7

Coordination mode7

Fig. S1. Coordination model of ligands in MOFs (AHU-TW1, 2, 4, 5, 6)8

Structural features of AHU-TW1, 2, 4, 5, 68

Fig. S2. (a) Coordination environment of AHU-TW1 (hydrogen atoms are omitted);

(b) 2D layer structure along b-axis; (c) 2D structure along c-axis; (d) 3D structure8

Fig. S3. (a) Coordination environment of AHU-TW2 (hydrogens atoms are omitted);

(b) 2D layer structure along c-axis; (c) 3D structure; (d) schematic view of topology

structure9

Fig. S4. (a) Coordination environment of AHU-TW4 (hydrogens atoms are omitted);

(b) 1D structure along a-axis ; (c) 2D layer structure along a-axis; (d) space packing

mode10

Fig. S5. (a) Coordination environment of AHU-TW5 (hydrogens atoms are omitted);

(b) 1D chain structure; (c) 2D layer structure along a-axis11

Fig. S6. (a) Coordination environment of AHU-TW6 (hydrogens atoms are omitted);

(b) 2D net structure ; (c) 3D interpenetrating structure12

Fig. S7. Pore size of AHU-TW1, 4, 613

Table S1. Crystal data and Structure Refinements for AHU-TW1-213

Table S2. Crystal data and Structure Refinements for AHU-TW4-614

Table S3. Selected bond distances (Å) and angles ( ° ) for AHU-TW1, 2, 4, 5 614

3

Structure discussion for AHU-TW317

Fig. S8. (a) Coordination environment of Zn-AHU-TW3 (hydrogens atoms are

omitted); (b) 2D layer structure of Zn-AHU-TW3; (c) the asymmetric unit of Zn-

AHU-TW3; (d) pore size of Zn-AHU-TW317

Table S4. Crystal Data and Structure Refinements for Zn-AHU-TW318

Fig. S9. Powder X-ray diffraction patterns of AHU-TW3 and Zn-AHU-TW319

Fig. S10. Proposed coordination environment and structure of AHU-TW3 19

X-ray powder diffraction analyse19

Fig. S11. Powder X-ray diffraction patterns of AHU-TW1, 2, 4, 5, 620

Prolonged stability of MOFs20

Fig. S12. Powder X-ray diffraction patterns of AHU-TW1, 3, 4, 6 in different

conditions: (a) as-synthesized; (b) thermally activated; in DMF (c), 0.01 M HCl (d),

water (e) and 0.01 M NaOH (f) for 24 h; (g) after TNP sensing21

Thermal stability of MOFs21

Fig. S13. TG curves of AHU-TW1-621

Photophysical Property21

Fig. S14. The solid-state UV–vis absorption spectra of ligands and MOFs21

Fig. S15. The solid state emission spectra of ligands and MOFs21

Table S5. Solid state photophysical parameters of ligands and AHU-TW1-622

Fig. S16. Photoluminescence spectra of (a) AHU-TW1, (b) AHU-TW3, (c) AHU-

TW4 and (d) AHU-TW6 in different solvents22

Scheme S2. The structural formulas of eight nitro compounds23

Selectivity for TNP and anti-interference ability23

Fig. S17. The fluorescence emission spectra of (a) AHU-TW1, (b) AHU-TW3, (c)

AHU-TW4, (d) AHU-TW6 in the DMF upon the addition of nitro compounds (under

the same condition)23

Fig. S18. Fluorescence quenching response of AHU-TW6 upon addition of various

nitro compounds (a) TCP, (b) TNT, (c) NB, (d) 2, 4-DNT, (e) 1, 3-DNB, (f) 2, 4-DNP

followed by the addition of TNP solution24

4

Fig. S19. Emission spectra of (a) AHU-TW1, (b) AHU-TW3, (c) AHU-TW4 and (d)

AHU-TW6 incremental addition of TNP solution and response

curve26

Table S6. A comparison of the Stern-Volmer constant (Ksv), detection limit and

solvent for the detection of TNP by luminescent MOFs

reported26

Fig. S20. HOMO and LUMO energies for the selected nitro compounds27

Table S7. HOMO and LUMO energy levels of selected nitro compounds and AHU-

TW627

Fig. S21. Normalized absorbance spectra of some nitro analytes and the normalized

emission spectra of MOFs in DMF solution28

Fig. S22. Selected decay curves monitored of MOFs in the presence or absence of

TNP: (a) AHU-TW1, (b) AHU-TW1-TNP, (c) AHU-TW3, (d) AHU-TW3-TNP, (e)

AHU-TW4, (f) AHU-TW4-TNP, (g) AHU-TW6, (h) AHU-TW6-

TNP29

Fig. S23. The resonance energy transfer efficiency of AHU-TW1, 3, 4, 629

Table. S8. The resonance energy transfer efficiency of AHU-TW1, 3, 4, 630

References30

5

Experiment sectionMaterials and apparatus

All chemicals were commercial obtained, solvents were purified by usual

methods, and used as received. The 1H NMR and 13C NMR spectra were recorded

with Bruker Advance spectrometer 400 MHz and 100 MHz spectrometer (TMS as

internal standard in NMR) using d6-DMSO or D2O as the solvents. IR spectra, as KBr

pellets, were recorded with a Nicolet FT-IR NEXUS 870 spectrometer (KBr discs) in

the 4000-400 cm-1 region. Mass spectrum was performed with a LCQ Fleet (ESI-MS).

The collection of data for single-crystal X-ray diffraction (SCXRD) analyses was

performed on a Bruker Apex II CCD equipped (296 K), with a sealed tube X-ray

source (Mo-Kα radiation, λ= 0.71073 Å) operating at 50 kV and 30 mA. The

structures were solved by direct methods and refined by full-matrix least-squares

refinement using the SHELXL-2018/3 program package. Elemental analysis was

carried out on a Perkin-Elmer 240 analyzer. The powder X-ray diffraction patterns

(PXRD) were collected with a scan speed of 0.5 s/deg on a Bruker Advance D8

(40kV, 40 mA) diffractometer with Cu radiation (λ= 1.54056 Å) at room temperature.

TGA data were obtained on a TGA-50 (SHIMADZU) thermogravimetric analyzer

with a heating rate of 10 °C·min-1 under N2 atmosphere.

Absorption spectra were recorded on a UV-265 spectrophotometer. Fluorescence

spectra were performed using a Hitachi F-7000 fluorescence spectrophotometer.

Computational details

Stern-volme was established to evaluate the quenching efficiency of TNP to the

complexes, namely, I0/I=1+KSV[M],1-3 where I represented the fluorescence intensity

before and after the addition of nitro compounds, KSV as the fluorescence quenching

coefficient, [M] as the concentration of nitro compound.

Synthesis of ligands

6

Scheme S1. Synthetic routes for ligands

Synthesis of 4, 4'-(phenylazanediyl)dibenzoic acid (H2L1)

The ligand H2L1 is synthesized efficiently according to the literature.4, 5 The

compounds of KMnO4 (9.98 g, 0.063 mmol) and K2CO3 (1.51 g, 0.109 mmol) in

moderate water was dropwise added to the solution of triphenylamine dialdehyde

(4.50 g, 0.015 mmol) in acetone (200 mL), for 12 h, accompanying with the magenta

disappears, it was filtered, the resulting mixture was carefully tuned pH to 1 and then

stirred at rt. for 2 h, the solvent was removed and recrystallized to get yellow solid

(3.65 g, Yield 73.1 %). 1H NMR (400 MHz, d6-DMSO): 12.65 (s, 2H), 7.88 (t, 4H),

7.43 (t, 2H), 7.23 (dd, 1H), 7.16 (d, 2H), 7.06 (d, 4H). 13C NMR (100 MHz, d6-

DMSO): 151.1, 145.9, 131.2, 124.6, 125.7. Anal. Calc. for C20H15NO4: C, 72.06%; H,

4.54 %; N, 4.20 %. Found, C, 71.86 %; H, 4.68 %; N, 4.49 %. ESI-MS(m/z), cal:

330.10, found: 332.17[M+].

Synthesis of 4,4'-(4-phenylpyridine-2,6-diyl)dibenzoic acid (H2L2)

4-phenyl-2,6-di-p-tolylpyridine:

A mixture of 4'-methyl-acetophenon (10.47 g, 0.078 mol), benzaldehyde (4.1 g,

0.039 mol), ammonium acetate (30 g, 0.389 mol), acetic acid (100 mL) were placed in

a round-bottom flask, the mixture was heated to 120 °C and stirred, refluxed for 5 h.

After cooling to room temperature, the solvent was removed by decompression to get

faint yellow solid and the crude product was recrystallized with ethyl alcohol absolute

in moderation, colorless transparent needle crystal was obtained. (5.00 g, Yield 30 %)

1H NMR (400 MHz, CDCl3): 8.10 (d, 4H, J = 8 Hz), 7.83 (s, 2H), 7.65 (d, 2H, J = 8

Hz), 7.34-7.31 (m, 6H), 2.44 (s, 6H). 13C NMR (100 MHz, CDCl3): 157.3, 149.8,

138.9, 138.8, 137.0, 136.2, 129.7, 129.3, 127.0, 116.2, 21.3, 21.2.

7

4-phenyl-2,6-di-p-tolylpyridine (4.50 g, 0.013 mol) was dissolved in mixed

solvents (75 mL of pyridine and 75 mL of H2O) in a round-bottom flask, stir to the

maximum, potassium permanganate (10.6 g, 0.067 mol) were added, then the reaction

mixture was stirred at 100 °C for 2 h. Mineral chameleon permanganate (10.6 g,

0.067 mol) were added again, stirred for 1 h. In the end of the reaction, colorless

transparency filtrate was obtained, then pyridine was removed by decompression, the

mixture was poured into plenty of water and carefully tuned acidic, large quantities of

off-white powder (4.3 g, Yield 90 %) were obtained, which were suction filtered off

and dried in vacuum. 1H NMR (400 MHz, d6-DMSO): 11.0 (s, 2H), 8.27 (d, 4H), 8.10

(s, 2H), 7.94 (d, 2H), 7.36 (t, 6H), 2.39 (s, 6H). 13C NMR (100 MHz, d6-DMSO):

167.1, 167.0, 155.7, 148.8, 142.3, 141.4, 131.5, 131.4, 129.9, 129.7, 127.7, 118.1.

Anal. Calc. for C20H15NO4: C, 72.06 %; H, 4.54 %; N, 4.20 %. Found, C, 71.86 %; H,

4.68 %; N, 4.49 %. ESI-MS(m/z), cal: 330.10, found: 332.17[M+].

Synthesis of 2,6-BIP

A mixture of imidazole (2.20 g, 33.77 mmol), 2,6-dibromopyridine (2.00 g, 8.44

mmol), potassium hydroxide (2.85 g, 50.73 mmol), tetrabutyl ammonium bromide

(0.30 g, 0.93 mmol), tetrahydrofuran (30 mL) was placed in a round-bottom flask and

then the mixture was re-fluxed at 70 °C for 48 h. After cooling to room temperature,

the mixture was evaporated, then poured into water, extracted twice with

dichloromethane, and the resulting mixture was dried over MgSO4, filtered, and

evaporated. The resulting residue was purified by chromatography over silica gel

eluting with petroleum ether, affording the compound as off white powder (3.50 g,

Yield 40 %). 1H NMR (400 MHz, d6-DMSO): 8.78 (s, 2H), 8.18 (dd, 3H), 7.77 (d,

2H), 7.17 (s, 2H). 13C NMR (100 MHz, d6-DMSO): 158.9, 134.5, 127.8, 112.5. Anal.

Calc. for C11H9N5: C, 62.56 %; H, 4.30 %; N, 33.16 %. Found: C, 62.45 %; H, 4.62 %;

N, 32.81 %.

Results and discussion

Coordination mode

8

Fig. S1. Coordination model of ligands in MOFs (AHU-TW1, 2, 4, 5, 6).

Structural features of AHU-TW1, 2, 4, 5, 6

Fig. S2. (a) Coordination environment of AHU-TW1 (hydrogen atoms are omitted); (b) 2D layer

structure along b-axis; (c) 2D structure along c-axis; (d) 3D structure.

AHU-TW1: The crystal structure determination reveals that AHU-TW1

crystallizes in a monoclinic space group C2/c (Fig. S2). X-ray single crystal

9

diffraction analysis reveals that the asymmetric unit of AHU-TW1 consists of one

independent Zn (II) ion, one H2L1 ligand, one 2, 6-BIP ligand and two free water

molecules. In the asymmetric unit, two dicarboxylate ligands are both monodentate.

The four coordinating atoms around Zn (II) are two oxygen atoms from carboxyl

groups and two N atoms from 2, 6-BIP, respectively, forming a distorted hexahedral

structure. The bond distances of Zn-O vary in the range of 1.9635(2)-1.9713(2) Å,

and the bond distances of Zn-N vary in the range of 2.006(2)-2.024(2) Å. All these

distances fall in the normal range found in reported Zn complexes. The H2L1 ligands

connect Zn (II) atoms to form a one-dimensional (1D) chain, then the 2, 6-BIP

ligands join all infinite 1D chains into a two-dimensional (2D) sheet, finally formed

three-dimensional (3D) framework structure by the bond of C-H-π.

Fig. S3. (a) Coordination environment of AHU-TW2 (hydrogens atoms are omitted); (b) 2D layer

structure along c-axis; (c) 3D structure; (d) schematic view of topology structure

AHU-TW2: crystallizes of AHU-TW2 in the orthogonal crystal system of Fdd2.

In the asymmetric unit, it contains an independent Co (II) cation, an H2L1 ligand, and

a 2, 6-BIP ligand (Fig. S3). The two carboxylic acid ions of H2L1 ligand were both

pattern of bidentate chelation. The six coordinating atoms around Co (II) are four

oxygen atoms (O1, O2, O3, O4) from two separated H2L1 ligands as well as two

nitrogen atoms (N2, N6) from 2, 6-BIP ligands, respectively, forming a distorted

10

octahedral geometry. The bond distances of Co-O ranging from 2.290(1) Å to 2.453(1)

Å and the bond distances of Co-N ranging from 2.280(1) Å to 2.453(1) Å, which can

be compared with values reported previously. The H2L1 are bridged by Co (II) ions to

generate 1D chains, and a triple interpenetrating 3D structure, which are formed by 2,

6-BIP ligands into higher dimensional frameworks.

Fig. S4. (a) Coordination environment of AHU-TW4 (hydrogens atoms are omitted); (b) 1D

structure along a-axis; (c) 2D layer structure along a-axis; (d) space packing mode

AHU-TW4: crystallizes of AHU-TW4 in the monoclinic crystal system in space

group Pbcn. The asymmetric unit contains one Zn (II) cation, one 2, 6-BIP ligand,

and one H2L2 ligand (Fig. S4). In the asymmetric unit, the two carboxylate groups of

the H2L2 ligand are both monodentate. The four coordinating atoms around Zn (II)

are two oxygen atoms (O1, O3) from carboxyl groups and two N atoms (N2, N0AA)

from 2, 6-BIP, respectively, forming a distorted hexahedral geometry. The bond

length of Zn-O varies in the range of 1.935(4)-2.013(8) Å and the bond distance of

Zn-N is from 2.036(1)-2.295(1) Å. All these distances and bond angles are within the

normal range. Through the connected of the first and end of H2L2 ligand, a 1D ‘‘V-

shape’’ link structure is formed, and the 1D chain by the π-π bond between hydrogen

bonds and aromatic rings that formed a 2D network structure.

11

Fig. S5. (a) Coordination environment of AHU-TW5 (hydrogens atoms are omitted); (b) 1D chain

structure; (c) 2D layer structure along a-axis

AHU-TW5: crystallizes of AHU-TW5 in the triclinic crystal system of Pī. In the

asymmetric unit, it contains an independent Co (II) cation, three H2L2 ligands, two 2,

6-BIP ligands (Fig. S5). One carboxylate group of the H2L2 ligand takes a bis-

monodentate coordination mode to bridge two Co (II) centers while the other

carboxylate group adopts a chelating in bidentate mode. Co (II) is six-coordinate, and

the coordination geometry for each Co (II) atom is a distorted octahedron with four O

atoms (O1, O2, O3, O4) from three H2L2 ligands and two N atoms (N1, N5) from

two 2, 6-BIP ligands. The bond lengths of Co-O vary in the range of 2.025(4)-2.240(4)

Å, and the bond distance of Co-N is 2.131(4)-2.140(4) Å. All these distances and

bond angles are within the normal range. Two H2L2 ligands connect two Co (II)

cation to form a [Co(CO2)4] units, and each [Co(CO2)4] unit binds to two adjacent

units through the other two H2L2 ligands to form a 1D chain. Finally, the chains are

connected by the 2, 6-BIP ligands to form a 2D sheet.

12

Fig. S6. (a) Coordination environment of AHU-TW6 (hydrogens atoms are omitted); (b) 2D net

structure; (c) 3D interpenetrating structure

AHU-TW6: crystallizes of AHU-TW6 in the triclinic crystal system in space

group Pī. As shown in Fig. S6, the asymmetric unit contains two Cd (II) cations, three

H2L2 ligands, two 2, 6-BIP ligands. For AHU-TW6, two dicarboxylate ligands take

different coordination modes, one is bis-monodentate while the other adopts a

chelating in bidentate mode. The six coordinating atoms around Cd (II) are four

oxygen atoms from carboxyl groups and two N atoms from 2, 6-BIP, respectively,

forming a distorted hexahedral structure. The bond distances of Cd-O ranging from

2.026(11) Å to 2.487(11) Å and bond distances of Cd-N ranging from 2.271(15) Å to

2.340(14) Å, which can be compared with values reported previously. The two H2L2

ligands connect Cd1 and Cd2 cations to form a [Cd(CO2)4] units, and each [Cd(CO2)4]

unit binds to two adjacent units through the other two H2L2 ligands to form a M2L2

ring, which the dihedral angle between the two ancillary ligands and the metal center

is 173.941°. The 2D network structure through the aromatic ring π-π bond between

the accumulation, which forming 3D network structure with double interspersed.

13

Fig. S7. Pore size of AHU-TW1, 4, 6.

Table S1. Crystal Data and Structure Refinements for AHU-TW1-2.

MOFs AHU-TW1 AHU-TW2

Empirical C31H23ZnN6O4.5 C31H24CoN6O5

Formula weight 616.92 619.49

Crystal system Monoclinic Orthorhombic

Space group C2/c Fdd2

a(Å) 26.9949(19) 18.099(4)

b(Å) 10.8305(7) 56.282(11)

c(Å) 21.8868(13) 13.435(3)

a[º] 90.00 90.00

b[º] 91.7250(1) 90.00

γ[º] 90.00 90.00

V(Å3) 6396.1(7) 13686(5)

Z 8 16

R1, wR2[I ≥2σ (I)] 0.0414, 0.1374 0.0758, 0.2106S on F2 1.226 1.013

14

Table S2. Crystal Data and Structure Refinements for AHU-TW4-6.

MOFs AHU-TW4 AHU-TW5 AHU-TW6

Empirical C72H50Zn2N14O15 C39H33CoN7O6 C78H66Cd2N14O12

Formula weight 1482.04 754.65 1616.24

Crystal system Orthorhombic Triclinic Triclinic

Space group Pbcn Pī Pī

a(Å) 23.937(3) 10.2264(14) 10.2023(12)

b(Å) 18.786(2) 11.4194(16) 11.5349(14)

c(Å) 15.8863(18) 16.870(2) 17.274(2)

a[º] 90.00 99.420(1) 99.987(1)

b[º] 90.00 92.468(2) 93.293(1)

γ[º] 90.00 105.420(2) 103.859(1)

V(Å3) 7143.8(14) 1865.8(4) 1933.3(4)

Z 4 2 1

R1, wR2[I ≥2σ (I)] 0.0646, 0.2091 0.0417, 0.1228 0.0323,0.1067

S onF2 1.062 1.093 1.152

Table S3. Selected bond distances (Å) and angles ( ° ) for AHU-TW1, 2, 4, 5, 6.

AHU-TW1

Zn1—O1#1 1.964(2) Zn1—N6#2 2.025(2)

Zn1—O3 1.971(2) Zn1—N2 2.007(2)

O1#1—Zn1—O3 106.95(9) O1#1—Zn1—N6# 113.93(10)

15

O1#1—Zn1—N2 119.45(10) O3—Zn1—N6#2 96.84(9)

O3—Zn1—N2 110.79(10) N2—Zn1—N6#2 106.57(10)

AHU-TW2

Co1—N2 2.280(12) Co1—O1#2 2.346(15)

Co1—O3 2.235(15) Co1—N6 2.295(12)

Co1—N6 2.295(12) N6#1—Co1—O1#2 93.6 (4)

N2—Co1—O3 139.7 (5) N2—Co1—O2#2 96.7 (5)

N2—Co1—N6#1 100.9 (5) O3—Co1—O2#2 100.7 (5)

O3—Co1—N6#1 84.3 (5) N6#1—Co1—O2#2 145.8 (5)

N2—Co1—O1#2 95.6 (5) O1#2—Co1—O2#2 55.4 (4)

O3—Co1—O1#2 124.1 (6)

AHU-TW4

Zn1—O1 1.935 (4) Zn1—N2 2.036 (5)

Zn1—O3#1 2.013 (8) Zn1—N0AA#2 2.031 (4)

O1—Zn1—O3#1 102.5 (3) O1—Zn1—N0AA#2 107.04 (17)

O1—Zn1—N2 99.95 (17) O3#1—Zn1—N2 112.1 (3)

N0AA#2—Zn1—N2 100.55 (19)

AHU-TW5

Co1—O3 2.025 (4) Co1—N1 2.140 (4)

Co1—O4#1 2.051 (4) Co1—O1#3 2.163 (4)

Co1—N5#2 2.131 (4) Co1—O2#3 2.240 (4)

O3—Co1—O4#1 119.41 (14) O4#1—Co1—O1#3 89.57 (14)

16

O3—Co1—N5#2 85.36 (15) N5#2—Co1—O1#3 94.08 (15)

O4#1—Co1—N5#2 86.17 (15) N1—Co1—O1#3 91.76 (15)

O3—Co1—N1 88.77 (15) O3—Co1—O2#3 91.47 (14)

O4#1—Co1—N1 95.47 (15) O4#1—Co1—O2#3 148.68 (15)

N5#2—Co1—N1 173.95 (16) O3—Co1—O1#3 150.84 (15)

O3—Co1—O1#3 150.84 (15) N1—Co1—O2#3 89.95 (16)

AHU-TW6

配合物 6Cd1—O4#3 2.226 (11) Cd2—N12#4 2.271 (15)

Cd1—N7#4 2.286 (14) Cd2—O3#3 2.270 (11)

Cd1—O5 2.276 (10) Cd2—O6 2.284 (12)

Cd1—O2 2.315 (10) Cd2—O8#3 2.322 (11)

Cd1—N3 2.334 (16) Cd2—N8 2.340 (14)

Cd1—O1 2.487 (11) Cd2—O7#3 2.427 (12)

O4#3—Cd1—N7#4 84.1 (5) N7#4—Cd1—N3 169.9 (6)

O4#3—Cd1—O5 122.2 (4) O5—Cd1—N3 86.9 (5)

N7#4—Cd1—O5 83.1 (5) O2—Cd1—N3 91.9 (5)

O4#3—Cd1—O2 89.9 (4) O4#3—Cd1—O1 144.6 (4)

N7#4—Cd1—O2 97.1 (5) N7#4—Cd1—O1 90.8 (5)

O5—Cd1—O2 147.6 (4) O5—Cd1—O1 91.7 (4)

O4#3—Cd1—N3 100.6 (5) O2—Cd1—O1 56.0 (4)

O3#3—Cd2—O6 124.8 (4) N3—Cd1—O1 90.4 (5)

N12#4—Cd2—O8#3 90.5 (5) N12#4—Cd2—O3#3 85.1 (5)

17

Structure discussion for AHU-TW3

Numerous attempts failed to grow AHU-TW3 crystals suitable for single-crystal

X-ray diffraction. Fortunately, we have determined the single crystal structure of an

analogue of AHU-TW3, [ZnL1(2,6-BIP)]·2H2O·DMF (denoted as Zn-AHU-TW3,

Table S4 and Fig. S8) bearing the same organic ligands with AHU-TW3. The crystal

data of Zn-AHU-TW3 was provided for reference only.

Fig. S8. (a) Coordination environment of Zn-AHU-TW3 (hydrogens atoms are omitted); (b) 2D

layer structure of Zn-AHU-TW3; (c) the asymmetric unit of Zn-AHU-TW3; (d) pore size of Zn-

AHU-TW3.

Zn-AHU-TW3: crystallizes of Zn-AHU-TW3 in the monoclinic crystal system

in space group C2/c. The asymmetric unit contains an independent Zn (II) cation, one

H2L1 ligand, one 2, 6-BIP ligand (Fig. S8). In the asymmetric unit, one carboxylate

O3#3—Cd2—O8#3 146.4 (4) N12#4—Cd2—O6 101.8 (5)

O6—Cd2—O8#3 88.7 (5) O3#3—Cd2—O7#3 93.1 (4)

N12#4—Cd2—N8 168.3 (4) O8#3—Cd2—N8 100.1 (4)

O3#3—Cd2—N8 83.3 (5) N1#4—Cd2—O7#3 90.5 (5)

O6—Cd2—N8 83.4 (5)

18

group adopts a chelating bidentate coordination mode while the other carboxylate

group adopts a monodentate coordination mode. Zn (II) is five-coordinated, bound

with three O atoms (O2, O3, O4) from two H2L1 ligands and two N atoms (N2, N6)

from the 2, 6-BIP ligand, respectively, forming a distorted octahedral geometry. Two

H2L1 ligands connect two Zn (II) units to form a 1D chain, and each 1D chain unit

binds to two adjacent units through the 2, 6-BIP ligand to form a 2D surface structure

(a very open framework structure with pore size 11.255 14.491 Å), which the sheets

are stacked in an ABAB fashion.

Table S4. Crystal Data and Structure Refinements for Zn-AHU-TW3

MOFs Zn-AHU-TW3

Empirical C60H48Zn2N12O9

Formula weight 1211.84

Crystal system Monoclinic

Space group C2/c

a(Å) 26.882(3)

b(Å) 10.8337(13)

c(Å) 21.914(3)

a[º] 90.00

b[º] 91.584(2)

γ[º] 90.00

V(Å3) 6379.7(13)

Z 4

R1, wR2[I ≥2σ (I)] 0.0367, 0.1454

S onF2 0.626

The powder X-ray diffraction (PXRD) pattern of as-synthesized AHU-TW3 is

essentially the same as that of Zn-AHU-TW3 (Fig. S9), revealing that it adopts the

19

same structure with Zn-AHU-TW3 (Fig. S10). Therefore, AHU-TW3 has a very

open framework structure similar with Zn-AHU-TW3 (Fig. S8).

Fig. S9. Powder X-ray diffraction patterns of AHU-TW3 and simulated Zn-AHU-TW3.

Fig. S10. Proposed coordination environment and structure of AHU-TW3.

X-ray powder diffraction analyse

20

Fig. S11. Powder X-ray diffraction patterns of AHU-TW1, 2, 4, 5, 6.

Prolonged stability of MOFs

21

Fig. S12. Powder X-ray diffraction patterns of AHU-TW1, 3, 4, 6 in different conditions: (a) as-

synthesized; (b) thermally activated; in DMF (c), 0.01 M HCl (d), water (e) and 0.01 M NaOH (f)

for 24 h; (g) after TNP sensing.

Thermal stability of MOFs

Fig. S13. TG curves of AHU-TW1-6.

Photophysical Property

Fig. S14. The solid-state UV–vis absorption spectra of ligands and MOFs.

Fig. S15. The solid state emission spectra of ligands and MOFs.

22

Table S5. Solid state photophysical parameters of ligands and AHU-TW1-6.

Complexes(nm)

𝑚𝑎𝑥𝑎𝑏𝑠 (nm)

𝑚𝑎𝑥𝑒𝑚

Stokes Shift (nm)

H2L1 364 433 69H2L2 343 397 54

2, 6-BIP 318 337 19AHU-TW1 343 417 74AHU-TW2 338 387 49AHU-TW3 361 414 53AHU-TW4 352 381 29AHU-TW5 343 382 39AHU-TW6 343 374 31

Fig. S16. Photoluminescence spectra of (a) AHU-TW1, (b) AHU-TW3, (c) AHU-TW4 and (d)

AHU-TW6 in different solvents.

23

Scheme S2. The structural formulas of eight nitro compounds.

Selectivity for TNP, anti-interference ability

Fig. S17. The fluorescence emission spectra of (a) AHU-TW1, (b) AHU-TW3, (c) AHU-TW4,

(d) AHU-TW6 in the DMF upon the addition of nitro compounds (under the same condition).

24

Fig. S18. Fluorescence quenching response of AHU-TW6 upon addition of various nitro

compounds (a) TCP, (b) TNT, (c) NB, (d) 2, 4-DNT, (e) 1, 3-DNB, (f) 2, 4-DNP followed by the

addition of TNP solution. Blank: the fluorescence spectra of AHU-TW6.

Firstly, as shown in Figure 4A, the quenching efficiency of TNP (~94%) are

much higher than other nitro compounds. In addition, the selectivity of AHU-TW6

(mainly discussed in the manuscript) towards TNP in the presence of other competing

nitro compounds have been performed to further demonstrate the high selectivity. In a

specially designed experiment, the luminescence emission spectrum of a well-

dispersed suspension of AHU-TW6 was initially collected and 0.5 mM of 2-NP

solution (50 μL) was added to the suspension, which was followed by the addition of

25

TNP solution (50 μL). Negligible quenching of the fluorescence of AHU-TW6 was

observed after the addition of 2-NP solution. However, the addition of 50 μL of TNP

solution to the suspension of AHU-TW6 containing the 2-NP solution led to

significant quenching of the fluorescence. The same trend (i.e. reduction in

fluorescence intensity) was observed in the subsequent addition sequence (i.e.,

addition of 2-NP solution, followed by the addition of TNP solution). The

fluorescence intensity was also decreased in an analogous, step-wise manner upon the

addition of the solutions of other nitro compounds, followed by the addition of TNP

solution to a DMF suspension of AHU-TW6. The results of these competitive

luminescence quenching experiments are shown in Fig. S18 and Fig. 5a. The results

clearly demonstrate that AHU-TW6 shows high selectivity for TNP, even in the

presence of other potentially interfering nitro compounds.

26

Fig. S19. Emission spectra of (a) AHU-TW1, (b) AHU-TW3, (c) AHU-TW4 and (d) AHU-TW6

incremental addition of TNP solution and response curve.

Table S6. A comparison of the Stern-Volmer constant (Ksv), detection limit and solvent for the

detection of TNP by reported sensors.

NO. MOF Ksv (104

M-1)Detection Limit Ref.

1 [ZnL1(2,6-BIP)]·2H2O·DMF (AHU-TW1)

1.48 4.05 × 10-6 M This work

2 [CdL1(2,6-BIP)]·2H2O·DMF (AHU-TW3)

1.44 3.94 × 10-6 M This work

3 [Zn2L2(2,6-BIP)]·DMF (AHU-TW4) 5.00 1.16 × 10-6 M This work

4 [CdL2(2,6-BIP)]·DMF (AHU-TW6) 5.31 1.10 × 10-6 M This work

5 [Zr6O4(OH)4(BTDB)6]·8H2O·6DMF 2.49 1.63 × 10-6 M 6

6 Benzo[c]cinoline-3,8-dicarboxylic acid 1.05 1.65 × 10-6 M 7

7 N1,N4-bis((pyridin-4-yl)methylene)benzene-1,4-diamine

2.97 5.00 × 10-6 M 8

8 [Cd(INA)(pytpy)(OH)·2H2O]n 4.30 2.41 × 10-6 M 9

9 {[Zn2(1,4-ndc)2(3-abpt)]2DMF}n 4.15 2.35 × 10-6 M 10

27

10 {[Cd(1,4-ndc)(3-abit)]H2O}n 4.90 2.47 × 10-6 M 10

11 (Z)-3-(4-butoxyphenyl)-2-[4-(butylamino)phenyl]acrylonitrile

2.37 1.96 × 10-6 M 11

12 M1 0.50 4.70 × 10-6 M 12

Compared with the reported conventional sensors to TNP (Table S7), the MOF

sensors hold their particular advantages, mostly as follows: (1) Compared with

organic sensor: the intimate contact between the MOF sensor and analyte due to the

porous frameworks, making them with high sensitivity and low detection limit;

repeatability of the sensors. (2) Compared with other reported MOF sensors: the

introduction of a functional auxiliary ligand (2, 6-BIP) provides more functional sites.

Fig. S20. HOMO and LUMO energy levels for the selected nitro compounds.

Table S7. HOMO and LUMO energy levels of selected nitro compounds and AHU-TW6.

Compounds HOMO (eV) LUMO (eV) Band Gap with AHU-TW6 (ELUMO)

2-NP -0.14780 -0.02062 0.05545

1,3-DNB -0.16355 -0.00990 0.06617

2,4-DNT -0.15991 -0.00996 0.06611

NB -0.14902 -0.01118 0.06489

TNP -0.15884 -0.05837 0.01770

TCP -0.24658 -0.04676 0.02931

28

Fig. S21. Normalized absorbance spectra of some nitro analytes and the normalized emission

spectra of MOFs in DMF solution.

TNT -0.31590 -0.15197 0.07590

2,4-DNP -0.28008 -0.15883 0.08276

AHU-TW6 -0.16422 -0.07607 0

29

Fig. S22. Selected decay curves monitored of MOFs in the presence or absence of TNP: (a) AHU-

TW1, (b) AHU-TW1-TNP, (c) AHU-TW3, (d) AHU-TW3-TNP, (e) AHU-TW4, (f) AHU-

TW4-TNP, (g) AHU-TW6, (h) AHU-TW6-TNP.

Fig. S23. The resonance energy transfer efficiency of AHU-TW1, 3, 4, 6.

30

Table S8. The resonance energy transfer efficiency of AHU-TW1, 3, 4, 6.

MOFs excited-state lifetime of MOFs in the

presence of TNP (τda)

excited-state lifetime of MOFs in the absence of TNP

(τd)

resonance energy transfer efficiency (E) of MOFs (E=1-

τda/τd)AHU-TW1 3.856679 × 10-9 2.759383 × 10-9 0.28451836

AHU-TW3 3.114276 × 10-9 2.025359 × 10-9 0.34965334

AHU-TW4 3.024396 × 10-9 1.771936 × 10-9 0.41411905

AHU-TW6 3.272681 × 10-9 1.593139 × 10-9 0.51320064

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