Supporting Information

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1 Supporting Information A Luminescent Terbium MOF Containing Hydroxyl Groups Exhibits Selective Sensing of Nitroaromatic Compounds and Fe(III) Ions Sanchari Pal and Parimal K. Bharadwaj * Department of Chemistry, Indian Institute of Technology Kanpur, , India pkb@iitk.ac.in 1

2 Synthesis of Ligand (H 3 L): Scheme S1. Synthetic route of H 3 L Methyl 2-(benzyloxy)-4-iodobenzoate (1) It was prepared following early reported method. 1 Solid K 2 CO 3 (6g, 44mmol) was added to a solution of methyl-4-iodosalicylate (6g, 22mmol) in dry MeCN at room temperature. To it benzyl bromide (3.7g, 22mmol) was added with a syringe and the resulting mixture was heated to 80 C and stirred overnight. The reaction mixture was then cooled to room temperature and filtered subsequently to remove insoluble salt which was washed further with MeCN. The filtrate was concentrated and extracted with EtOAc/H 2 O. Slow evaporation of the solvent afforded crystalline product which was directly used for next step. Yield: 6 g (90%). 1 H-NMR (CDCl 3, 500 MHz), δ (ppm): 3.92 (s, 3H); 3.95 (s, 6H); 5.22 (s, 2H); 7.07 (s, 1H); 7.15 (d, J = 8.5 Hz, 1H); 7.33 (d, J = 7.3 Hz, 1H); 7.40 (t, J = 7.3 Hz, 2H); 7.52 (d, J = 7.3 Hz, 2H); 7.95 (d, J = 7.9 Hz, 1H) (Figure S1); 13 C-NMR (CDCl 3 ), δ (ppm): 52.21, 70.91, , , , , 128, , , , , , (Figure S2). 2

3 Figure S1. 1 H NMR spectrum of 1. Figure S2. 13 C NMR spectrum of 1. 3

4 3,5-diethyl 4'-methyl 3'-(benzyloxy)biphenyl-3,4',5-tricarboxylate (2) 4 g (11 mmol) Methyl 2-(benzyloxy)-4-iodobenzoate (1), 3.5 g (13 mmol) 3,5- bis(ethoxycarbonyl)phenylboronic acid and 3 g (22 mmol) K 2 CO 3 were added to a mixture of 80 ml toluene, 40 ml EtOH and 40 ml water in 250 ml round bottom flask. It was degassed under N 2 using Schlenk line at 80 C for 15 minutes. Then 250 mg, (0.02 mmol) freshly prepared [Pd(PPh 3 ) 4 ] was added to the solution. Then the mixture was refluxed for 24 hours with constant stirring under constant flow of nitrogen. The reaction mixture was allowed to cool and organic solvents were evaporated. Then it was extracted from EtOAc and washed with brine and dried over Na 2 SO 4. Chromatographic purification of the crude material on silica gel column using 5% EtOAc in hexane afforded compound 2 as white powder. Yield: 2.5 g (80%). 1 H-NMR (CDCl 3, 400 MHz), δ (ppm): 1.43 (t, J = 6.8 Hz, 3H); 3.92 (s, 3H); 4.44 (q, J = 6.8 Hz, 4H); 5.27 (s, 2H); (m, J = 7.8 Hz, 5H); 7.53 (d, J = 7.3 Hz, 2H); 7.93 (d, J = 8.1 Hz, 2H); 8.39 (s, 2H); 8.67 (s, 1H) (Figure S3); 13 C-NMR (CDCl 3 ), δ (ppm): 14.44, 52.20, 61.69, 71.00, , , , , , , , , , , , , , , (Figure S4). ESI-MS: m/z (100%) [M + ] (Figure S5). Figure S3. 1 H NMR spectrum of 2. 4

5 Figure S4. 13 C NMR spectrum of 2. Figure S5. ESI-MS spectrum of 2. 5

6 3,5-diethyl 4'-methyl 3'-hydroxybiphenyl-3,4',5-tricarboxylate (3) Compound 2 (3g, 6.5mmol) was dissolved in 50 ml dry THF and to it Pd/C (10% by weight) was added. Then hydrogen gas was purged in it, making the system completely closed and stirred well at room temperature for 48 h. The Pd/C was then filtered with a good filter paper and washed well. Recrystallization with EtOAc gave pure white compound. Yield: 1.5 g (80%). 1 H-NMR (CDCl 3, 400 MHz), δ (ppm): 1.42 (t, J = 7.3 Hz, 6H); 3.97 (s, 3H); 4.44 (q, J = 6.8 Hz, 4H); 7.18 (d, J = 6.8 Hz 1H); 7.27 (s, 1H); 7.92 (d, J = 8.1 Hz, 1H); 8.45 (s, 2H); 8.68 (s, 1H); 8.67 (s, 1H); (s, 1H) (Figure S6); 13 C-NMR (CDCl 3 ), δ (ppm): 14.44, 52.52, 61.67, 71.00, , , , , , , , , , , , (Figure S7). ESI-MS: m/z (100%) [M+1 + ] (Figure S8). Figure S6. 1 H NMR spectrum of 3. 6

7 Figure S7. 13 C NMR spectrum of 3. Figure S8. ESI-MS spectrum of 3. 7

8 3'-hydroxybiphenyl-3,4',5-tricarboxylic acid (H 3 L) The triester compound (3) was hydrolyzed by refluxing with 6(N) KOH solution (50 ml) for 24 h. Finally the resulting solution was carefully acidified in cold condition, with dropwise addition of 6(N) HCl to obtain a white precipitate. Keeping flask overnight in the freezer, the white solid was collected by filtration, washed thoroughly with water and dried at 80 o C under vacuo. Yield: 1.5 g (80%). 1 H-NMR (CDCl 3, 400 MHz), δ (ppm): (m, 2H); 7.87 (d, J = 9.0 Hz, 1H); 8.34(s, 2H); 8.45 (s, 1H); (s, 3H); (Figure S9); 13 C-NMR (CDCl 3 ), δ (ppm): , , , , , , , , , , , (Figure S10). ESI-MS: m/z (100%) [M-1 + ] (Figure S11). Figure S9. 1 H NMR spectrum of H 3 L. 8

9 Figure S C NMR spectrum of H 3 L. Figure S11. ESI-MS spectrum of H 3 L. 9

10 Table S1. Crystal and Structure Refinement Data for 1. Complexe 1 Empirical formula C23 H26 N2 O9.5 Tb Formula wt Crystal system Tetragonal Space group I4 1 /a a, Å (6) b, Å (6) c, Å (3) α ( ) 90 β ( ) 90 γ ( ) 90 U, Å (5) Z 16 ρ calc g/cm μ, mm F(000) 4256 Reflns collected R int Independent reflns 5442 Refinement method full-matrix leastsquares on F 2 GOF Final R indices [I>2σ(I)] R1 = wr2 = R indices (all data) R1 = wr2 =

11 Comments on checkcif: Framework 1 Alert level A PLAT213_ALERT_2_A Atom C7 has ADP max/min Ratio prolat PLAT234_ALERT_4_A Large Hirshfeld Difference N1 -- C Ang. PLAT234_ALERT_4_A Large Hirshfeld Difference N1 -- C Ang. PLAT241_ALERT_2_A High MainMol Ueq as Compared to Neighbors of C7 Check PLAT242_ALERT_2_A Low MainMol Ueq as Compared to Neighbors of O5 Check PLAT242_ALERT_2_A Low MainMol Ueq as Compared to Neighbors of N1 Check Alert level B PLAT213_ALERT_2_B Atom O6A has ADP max/min Ratio prolat PLAT220_ALERT_2_B Non-Solvent Resd 1 C Ueq(max)/Ueq(min) Range 10.0 Ratio PLAT230_ALERT_2_B Hirshfeld Test Diff for C6 -- C s.u. PLAT342_ALERT_3_B Low Bond Precision on C-C Bonds Ang. PLAT430_ALERT_2_B Short Inter D...A Contact O2A.. O3A Ang. Author response: The single crystal structure has severe disorders in framework as well as coordinated and lattice solvent molecules and we have tried several times to get a good crystal data but unable to get it. Therefore we have refined the data with squeeze command by PLATON software. The alert level A and B arises due to the disorders in the crystal especially in the coordinated DMA molecule. We have collected data on different crystals with the same result. 11

12 Table S2. Selected Bond Distances (Å) and Bond Angles ( o ) in 1. complex Bond lengths Bond angles 1 Tb(01)-O(2A)# (9) O(2A)#4-Tb(01)-O(5A)# (3) Tb(01)-O(5A)# (8) O(2A)#4-Tb(01)-O(5) 77.6(4) Tb(01)-O(3A)# (8) O(5A)#5-Tb(01)-O(5) 130.2(3) Tb(01)-O(6A)# (8) O(2A)#4-Tb(01)-O(1A) 133.3(4) Tb(01)-O(4A)# (8) O(5A)#5-Tb(01)-O(1A) 70.8(3) Tb(01)-O(4A)# (8) O(5)-Tb(01)-O(1A) 73.0(4) Tb(01)-O(1A) 2.335(9) O(2A)#4-Tb(01)-O(3A)#6 76.0(4) Tb(01)-O(5) 2.329(8) O(5A)#5-Tb(01)-O(3A)# (3) O(5)-Tb(01)-O(3A)#6 75.1(4) O(1A)-Tb(01)-O(3A)# (4) O(2A)#4-Tb(01)-O(6A)#7 76.6(4) O(5A)#5-Tb(01)-O(6A)# (4) O(5)-Tb(01)-O(6A)#7 86.3(4) O(1A)-Tb(01)-O(6A)#7 66.2(4) O(3A)#6-Tb(01)-O(6A)# (4) O(2A)#4-Tb(01)-O(4A)#8 77.3(3) O(5A)#5-Tb(01)-O(4A)#8 74.3(3) O(5)-Tb(01)-O(4A)# (3) O(1A)-Tb(01)-O(4A)# (4) O(3A)#6-Tb(01)-O(4A)#8 78.1(3) O(6A)#7-Tb(01)-O(4A)# (3) O(2A)#4-Tb(01)-O(4A)# (3) O(5A)#5-Tb(01)-O(4A)#6 67.7(3) O(5)-Tb(01)-O(4A)#6 74.3(3) O(1A)-Tb(01)-O(4A)#6 81.8(3) O(3A)#6-Tb(01)-O(4A)#6 50.1(3) O(6A)#7-Tb(01)-O(4A)# (3) O(4A)#8-Tb(01)-O(4A)# (2) 12

13 Figure S12. IR spectrum of 1. Figure S13. Thermogravimetric (TG) spectrum of 1. 13

14 Figure S14. Variable temperature PXRD of 1 and activated sample (1 ). (a) (b) (c) (d) (e) 14

15 Figure S15. (a) 1D metal (Tb)-oxygen chain along crystallographic c-axis. Linker L connecting the Tb-O chain along crystallographic (b) b axis and (c) a-axis forming (d) 3D box like framework. (e) a representation of the new 6,6-c net of 1. Figure S16. The PXRD pattern of 1 after immerging in several solvents. Luminescence measurements For all quantitative measurements, 5 mg of the powered sample (1 ) was dispersed in 5 ml DMF and sonicated until homogeneous suspension was obtained. This solution was then diluted to 100 ml to afford the DMF-suspended 1 and used as the stock solution for all the measurements. To measure the quenching constant, in 1 ml of the stock solution of 1 representative micro liter amount of 1mM NAC analytes were gradually added and measured as depicted in the following figures ( Figure S17 to S21). For different metal ions, in 0.5 ml of stock solution of 1, 0.5 ml of 0.1 (M) DMF solutions of metal ions have been added and 15

16 measured. For quantitative measurements with Fe(III) ions, total of 1 ml experimental solutions were made by adding 0.5 ml of stock solution of 1 and required amount of 0.1 (M) of Fe(NO 3 ) 3 solution and DMF. Figure S17. Emission spectra of 1 dispersed in DMF-stock solution (1 ml) upon incremental addition (µl) of nitrobenzene (NB) solution (1 mm ) in DMF. Figure S18. Emission spectra of 1 dispersed in DMF-stock solution (1 ml) upon incremental addition (µl) of 1,4-dinitrobenzene (DNB) solution (1 mm ) in DMF. 16

17 Figure S19. Emission spectra of 1 dispersed in DMF-stock solution (1 ml) upon incremental addition (µl) of 2,4-dinitrochlorobenzene (DNCB) solution (1 mm ) in DMF. Figure S20. Emission spectra of 1 dispersed in DMF-stock solution (1 ml) upon incremental addition (µl) of 4-nitrophenol (NP) solution (1 mm ) in DMF. 17

18 Figure S21. Emission spectra of 1 dispersed in DMF-stock solution (1 ml) upon incremental addition (µl) of trinitrophenol (TNP) solution (1 mm ) in DMF. Figure S22. The PXRD pattern of 1 after immerging in several NAC-analytes. 18

19 Figure S23. Fluorescence intensity ratio histograms of 1 dispersed in different metal ions (green) and subsequent addition of Fe(NO 3 ) 3 (red) in DMF. Figure S24. Dependence of quenching efficiency on the concentration of Fe(III). 19

20 (a) (b) Figure S25. Reversibility test for sensing (a) Fe(NO 3 ) 3 and (b) trinitrophenol up to three cycles. Figure S26. The PXRD pattern of 1 after immerging in Fe(NO 3 ) 3, Cu(NO 3 ) 2 and after three cycle reversibility test with Fe(NO 3 ) 3 and trinitrophenol. 20

21 Figure S27. IR-spectra of 1 (green line) and 1 in presence of nitrobenzene (black line) Table S3: EDS Analysis 1. Fe Tb 001 nd nd Average Standard deviation Fe Tb

22 003 nd nd Average Standard deviation Fe Tb Average Standard deviation

23 (a) (b) 23

24 (c) Figure S28. (a) Absorption spectra of DMF-solution containing Fe(NO 3 ) 3, Fe(ClO 4 ) 2, Cu(NO 3 ) 2 and other metal ions(10-3 M); green line represents the absorption spectra of 1 suspended stock solution in DMF, green line represents the average absorption spectra of other experimental metal ions incorporated 1, (b) The absorption spectrum of Fe(NO 3 ) 3 and excitation (blue spectrum) spectra of 1 suspended stock solution in DMF. (c) The absorption (black spectrum) and excitation (blue spectrum) spectra of 1 suspended stock solution in DMF. Gas adsorption study Due to the porous character of the framework and availability of surface functionalized channels of 1, gas adsorption studies were conducted up to a relative pressure (p/p o ) of 1.0 bar. Before measurement, 1 was activated and measurements were performed. CO 2 adsorption experiment showed typical type I adsorption behavior with little hysteresis (Figure S28a) at 273 and 298 K, confirming the microporous nature of 1. From the low-pressure region, gradually 1 starts to take up CO 2. The maximum CO 2 uptakes (1 bar) at 273 and 298 K for 1 are 24.7 and 18.9 cm 3 g 1, respectively. The BET and Langmuir surface area was calculated as and m 2 /g respectively and the pore volume was measured 24

25 (a) (b) Figure S29. (a) Sorption isotherms for 1' : red- CO 2 at 273 K, green- CO 2 at 298 K, blue- N 2 at 77K. (b) Isosteric heat of CO 2 adsorption (Q st ) cm 3 /g for CO 2 uptake at 273 K. To have more insight on the interaction of the framework with the CO 2, the isosteric heat of CO 2 adsorption (Q st ) of 1 was evaluated utilizing the Clausius Clayperon equation, 2 from the isotherms obtained at 273 and 298 K. As revealed in figure S28b, the Qst value for CO 2 is kj mol 1 at zero coverage. Reference: (1) Deng, H.; Grunder, S.; Cordova, K. E.; Valente, C.; Furukawa, H.; Hmadeh, M.; Gándara, F.; Whalley, A. C.; Liu, Z.; Asahina, S.; Kazumori, H.; O Keeffe, M.; Terasaki, O.; Stoddart, J. F.; Yaghi, O. M. Science, 2010, 336, (2) Kaye, S. S; Long, J. R. J. Am. Chem. Soc., 2005, 127,