Cocrystal Engineering of a Prototype Energetic Material: Supramolecular Chemistry of 2,4,6- Trinitrotoluene. Kira B. Landenberger and Adam J.

Transcription

1 Cocrystal Engineering of a Prototype Energetic Material: Supramolecular Chemistry of 2,4,6- Trinitrotoluene Kira B. Landenberger and Adam J. Matzger* Department of Chemistry and the Macromolecular Science and Engineering Program, University of Michigan, 930 N. University Avenue, Ann Arbor MI Supporting Information. Table of Contents SI 1. Experimental SI 2. Raman Spectra of TNT Cocrystals SI 3. Nitro Stretching Frequencies in Raman Spectra SI 4. Crystallographic Data of TNT Cocrystals SI 5. References 1

2 SI 1. Experimental Materials Naphthalene (98%), anthracene (99%), 9-bromoanthracene (94%), phenanthrene (98+%), dibenzothiophene (98%), 2-amino-4,5-dimethoxybenzoic acid (98%) and perylene (99%) were obtained from Aldrich (Milwaukee, WI). Tetrathiafulvalene (97%), 4,6-dimethyldibenzothiophene (97%), 1,4- dimethoxybenzene (99%) and 1,2-phenylenediamine (99.5%) were obtained from Aldrich, (St. Louis, MO). Phenothiazine and 1-bromonaphthalene (97%) were obtained from Sigma (St. Louis, MO). Anthranilic acid (puriss, >99.5%) was obtained from Fluka (Steinheim, Switzerland). 2,4,6- Trinitrotoluene 1 and thieno[3,2-b]thiophene 2 were synthesized and purified according to the published procedures. Caution! 2,4,6-Trinitrotoluene is an energetic material and care should be exercised in avoiding excessive heat, static electricity and mechanical shock! Cocrystal Formation High throughput screening (HTS) experiments were performed in 96 well polypropylene plates. Solutions were dispensed into the plates using either a Gilson 215 liquid handler or an Eppendorf EpMotion 5070 liquid handling robot. A 10 mg/ml (0.044 M) solution of TNT in ethanol (Decon Labs, Inc., 200 Proof, USP) was dispensed throughout the plate; the volumes dispensed across each row were 0, 2, 2, 3, 4, 3, 4, 4, 6, 6, 6, and 4 µl. A different cocrystal former solution (0.044 M) was dispensed for every row; the volumes dispensed across each row were 6, 8, 6, 6, 6, 4, 4, 3, 4, 3, 2, and 0 µl. Cocrystal formers screened were dissolved in ethanol when possible. Cocrystal formers anthracene, 9- bromoanthracene, and tetrathiafulvalene were dissolved in inhibitor free tetrahydrofuran (Fisher Chemical, HPLC Grade). Other solvents used for the screening process include methanol (Fisher Chemical, Certified ACS), dimethylsulfoxide (Fisher Chemical, HPLC Grade), and toluene (Fisher Chemical, Certified ACS). The solutions were mixed, covered and allowed to evaporate at room temperature over a period of three days. The resulting ratios of cocrystal former to TNT were 1:4, 1:3, 1:2, 2:3, 3:4, 1:1, 4:3, 3:2, 2:1, and 3:1. Additional Crystallizations Additional crystallizations were performed to produce cocrystals for powder X-ray diffraction (PXRD), thermal analysis and single crystal X-ray diffraction. TNT:naphthalene (1) mg TNT and mg naphthalene in 1 ml ethanol, 6.1 mg TNT and 3.7 mg naphthalene in 0.7 ml ethanol, mg TNT and mg naphthalene in acetone; TNT:anthracene (3) mg TNT and mg anthracene in 0.5 ml tetrahydrofuran (THF), mg TNT and mg anthracene in 0.5 ml THF; 2

3 TNT:9-bromoanthracene (4) mg TNT and mg of 9-bromoanthracene in 0.5 ml acetonitrile, 10.4 mg TNT and 11.8 mg 9-bromoanthracene in 1 ml THF; TNT:phenanthrene (5) mg TNT and mg phenanthrane in 0.5 ml ethanol; TNT:tetrathiafulvalene (7) mg TNT and mg tetrathiafulvalene in 0.5 ml THF; TNT:thieno[3,2-b]thiophene (8) 6.7 mg TNT and 4.6 mg thieno[3,2-b]thiophene in 0.7 ml ethanol, mg TNT and mg thieno[3,2- b]thiophene in acetone, mg TNT and mg thieno[3,2-b]thiophene in ethanol; TNT:phenothiazine (9) mg TNT and mg phenothiazine in 0.5 ml ethanol; mg TNT and mg phenothiazine in ethanol; TNT:dibenzothiophene (10) mg TNT and mg dibenzothiophene in 0.5 ml ethanol; TNT:4,6-dimethyldibenzothiophene (11) 2.0 mg TNT and 1.9 mg 4,6-dimethyldibenzothiophene in 0.4 ml of ethanol; TNT:1,2-phenylenediamine (12) mg TNT and mg 1,2-phenylenediamine in 1 ml of methanol; mg TNT and mg 1,2- phenylenediamine in a 1:1 mixture by volume of THF and ethanol; TNT:1,4-dimethoxybenzene (13) mg TNT and mg 1,4-dimethoxybenzene in 1.6 ml ethanol; TNT:4-aminobenzoic acid 1:1 (14) mg TNT and mg 4-aminobenzoic acid in 1.4 ml ethanol; TNT:anthranilic acid 1:1 (16) mg TNT and mg anthranilic acid in 1 ml ethanol. Thermomicroscopy Thermomicroscopy was performed with a Linkham LTS 350 hot stage connected to a Linkham TMS 94 processor and controlled using Linksys32 Version software, viewed under polarized light with a Nikon Eclipse E600 microscope. For initial observation, samples were heated from room temperature up to temperatures ranging from 50 to 200 C at a rate of 1 C/min. Fused samples were cooled and identified using Raman spectroscopy. Thermomicroscopy was used to form three TNT cocrystals: TNT:1-bromonaphthalene (2) 1 mg of TNT in excess 1-bromonaphthalene was heated at a rate of 1 ºC/min to 50 ºC and held for 15 minutes, cooled and allowed to sit for 24 hours; TNT:4-aminobenzoic acid 1:2 (15) 1 mg of the 1:1 TNT-4-aminobenzoic acid cocrystal was heated at 10 ºC/min to 107 ºC and held there for 15 minutes; TNT:anthranilic acid 1:2 (17) 1 mg of both TNT and anthranilic were mixed, placed on a microscope slide under cover slip, heated up to 120 C at 1 C/min, and held at this temperature for 1 hour. Raman Spectroscopy Raman spectra were obtained using a Renishaw invia Raman microscope equipped with a 633 nm He- Ne laser and a 514 nm argon laser with 1800 lines/mm grating and a RenCam CCD detector. Spectra were collected and analyzed using the WiRE 3.1 software package. Calibration was performed using a 3

4 silicon standard. Spectra were collected using an Olympus SLMPlan 20 objective (numerical aperture = 0.35) and 50 μm slit in extended scan mode with a range of cm -1. Powder X-Ray Diffraction Powder X-ray diffraction (PXRD) patterns were collected at 95 K using a Rigaku R-Axis Spider diffractometer with an image plate detector and graphite monochromated Cu-Kα radiation ( Å). Samples were mounted on a CryoLoop and images were collected for ten minutes while rotating the sample about the φ-axis at 10 /sec, oscillating ω between 120 and 180 at 1 /sec with χ fixed at 45. Images were integrated from 3 to 70 with a 0.05 step size using AreaMax 2 software. Powder patterns were processed in Jade Plus. Single Crystal X-ray Diffraction All measurements were made on a Rigaku R-Axis Spider diffractometer with an image plate area detector using graphite monochromated Cu-Kα radiation ( Å). All collections were carried out at 95 K with the sample mounted on a MiTeGen MicroMount. The structures were solved by direct methods 3,4 and expanded using Fourier techniques. 5 The non-hydrogen atoms were refined anisotropically and the hydrogen atoms were refined using the riding model. The final cycle of fullmatrix least-squares refinement was made on F 2. An empirical absorption correction was applied to the structure. All calculations were performed using the CrystalStructure crystallographic software package except for refinement, which was performed using SHELXL For determination of interand intramolecular distances, all carbon-hydrogen bond lengths were normalized to Å, all nitrogen-hydrogen bond lengths were normalized to Å and all oxygen-hydrogen bond lengths were normalized to Å. Structures 1, 2, 4, 7, 8, 10, 11, and 16 all exhibit low completeness due to the triclinic space group and the copper X-ray radiation source employed; data collection strategies to achieve the maximum possible completeness were used. Structure 17 has a relatively high R factor (0.0944). The method for the formation of this 1:2 cocrystal introduces disorder within the bulk of the crystal and therefore good quality crystals of adequate size for single crystal X-ray diffraction could not be grown. In structures 6 and 9 large C-C bond uncertainties (>0.01 Å) were observed (0.011 and Å respectively). Quality crystals of 6 were not obtainable; this cocrystal exhibits a significant amount of disorder in the nitro groups of the TNT, and the best crystal selected still diffracted weakly. Despite considerable effort, high quality crystals, without twinning, of 9 were not obtainable; this cocrystal structure exhibits a significant amount of disorder, particularly in two of the nitro groups of TNT as a result of the various conformations possible for these groups. Due to poor crystal quality large C-C 4

5 bond uncertainties were observed. The disorder in the nitro groups also contributed significantly to increasing the ADP values of two oxygen atoms, O1B and O5B. Differential Scanning Calorimetry Thermograms of the samples were recorded on a TA Instruments Q10 differential scanning calorimeter and programmed using Thermal Advantage for Q Series Version 2.5. Samples (0.5-2 mg weighed to a precision of mg) were placed in aluminum pans and the lids were crimped using a TA- Instruments hermetic sealing press. Thermal behavior of the samples was studied under a nitrogen purge of 50.0 ml/min at a heating rate of 10 C/min, over a temperature range of C. The instrument was calibrated with an indium standard. Data were analyzed using Universal Analysis Version 4.3 Thermal Advantage Software. Calculations Packing coefficients were calculated by using the following equation: C k = ZV mol V 1 cell, where C k is the packing coefficient, Z is the number of molecules in the unit cell, V mol is the molecular volume (Å 3 ), and V cell is the volume of the unit cell. Molecular volume was calculated with Spartan 08 version (Wavefunction, Inc.), which employs van der Waals radii of 1.89 Å for bromine, 1.92 Å for carbon, 1.20 Å for hydrogen, 1.55 Å for nitrogen, 1.52 Å for oxygen, and 1.82 Å for sulfur. Torsion angles were determined using Mercury Torsion angles were calculated by measuring the angle between the plane of the benzene ring and the plane formed by the nitrogen and two oxygen atoms of the nitro group. Calculations of the electrostatic potential energy density maps were performed using semi-empirical methods with the AM1 model available in Spartan 08 version (Wavefunction, Inc.). All maps were normalized between -25 and 25 kj/mol. 5

6 SI 2. Raman Spectra of TNT Cocrystals Figure S1. Raman spectra of TNT:naphthalene cocrystal, naphthalene and monoclinic TNT Figure S2. Raman spectra of TNT:1-bromonaphthalene cocrystal, 1-bromonaphthalene and monoclinic TNT 6

7 Figure S3. Raman spectra of TNT:anthracene cocrystal, anthracene and monoclinic TNT Figure S4. Raman spectra of TNT:9-bromoanthracene cocrystal, 9-bromoanthracene and monoclinic TNT 7

8 Figure S5. Raman spectra of TNT:phenanthrene cocrystal, phenanthrene and monoclinic TNT Figure S6. Raman spectra of TNT:tetrathiafulvalene cocrystal, tetrathiafulvalene and monoclinic TNT 8

9 Figure S7. Raman spectra of TNT:thieno[3,2-b]thiophene cocrystal, thieno[3,2-b]thiophene and monoclinic TNT. Figure S8. Raman spectra of TNT:phenothiazine cocrystal, phenothiazine and monoclinic TNT. 9

10 Figure S9. Raman spectra of TNT:dibenzothiophene cocrystal, dibenzothiophene and monoclinic TNT. Figure S10. Raman spectra of TNT:4,6-dimethyldibenzothiophene cocrystal, 4,6-dimethyldibenzothiophene and monoclinic TNT. 10

11 Figure S11. Raman spectra of TNT:1,2-phenylenediamine cocrystal, 1,2-phenylenediamine and monoclinic TNT. Figure S12. Raman spectra of TNT:1,4-dimethoxybenzene cocrystal, 1,4-dimethoxybenzene and monoclinic TNT. 11

12 Figure S13. Raman spectra of TNT:4-aminobenzoic acid 1:1 cocrystal, 4-aminobenzoic acid and monoclinic TNT. Figure S14. Raman spectra of TNT:4-aminobenzoic acid 1:2 cocrystal, 4-aminobenzoic acid and monoclinic TNT. 12

13 Figure S15. Raman spectra of TNT:anthranilic acid 1:1 cocrystal, anthranilic acid form II and monoclinic TNT. Figure S16. Raman spectra of TNT:anthranilic acid 1:2 cocrystal, anthranilic acid form II and monoclinic TNT. 13

14 Table S1. Frequency of Raman vibrational modes (cm -1 ) of TNT cocrystals

15 SI 3. Nitro Stretching Frequencies in Raman Spectra Table S2. Observed frequencies (cm -1 ) for the asymmetric and symmetric nitro stretch of TNT in both pure and the TNT cocrystals TNT/TNT cocrystal ν as NO ν 2 s NO 2 monoclinic TNT orthorhombic TNT naphthalene anthracene bromoanthracene phenanthrene tetrathiafulvalene thieno[3,2-b]thiophene phenothiazine dibenzothiophene ,6-dimethyldibenzothiophene ,2-phenylenediamine ,4-dimethoxybenzene aminobenzoic acid 1: aminobenzoic acid 1: anthranilic acid 1: anthranilic acid 1:

16 SI 4. Crystallographic Data of TNT Cocrystals TNT:naphthalene cocrystal Figure S17. ORTEP diagram of TNT:naphthalene cocrystal Figure S18. Simulated (bottom) and experimental (top) PXRD of TNT:naphthalene cocrystal. 16

17 TNT:1-bromonaphthalene cocrystal Figure S19. ORTEP diagram of TNT:1-bromonaphthalene cocrystal Figure S20. Simulated (bottom) and experimental (top) PXRD of TNT:1-bromonaphthalene cocrystal. 17

18 TNT:anthracene cocrystal Figure S21. ORTEP diagram of TNT:anthracene cocrystal Figure S22. Simulated (bottom) and experimental (top) PXRD of TNT:anthracene cocrystal. 18

19 TNT:9-bromoanthracene cocrystal Figure S23. ORTEP diagram of TNT:9-bromoanthracene cocrystal Figure S24. Simulated (bottom) and experimental (top) PXRD of TNT:9-bromoanthracene cocrystal. 19

20 TNT:phenanthrene cocrystal Figure S25. ORTEP diagram of TNT:phenanthrene cocrystal Figure S26. Simulated (bottom) and experimental (top) PXRD of TNT:phenanthrene cocrystal. 20

21 TNT:perylene cocrystal Figure S27. ORTEP diagram of TNT:perylene cocrystal Figure S28. Simulated (bottom) and experimental (top) PXRD of TNT:perylene cocrystal. 21

22 TNT:tetrathiafulvalene cocrystal Figure S29. ORTEP diagram of TNT:tetrathiafulvalene cocrystal Figure S30. Simulated (bottom) and experimental (top) PXRD of TNT:tetrathiafulvalene cocrystal. 22

23 TNT:thieno[3,2-b]thiophene cocrystal Figure S31. ORTEP diagram of TNT:thieno[3,2-b]thiophene cocrystal Figure S32. Simulated (bottom) and experimental (top) PXRD of TNT:thieno[3,2-b]thiophene cocrystal. 23

24 TNT:phenothiazine cocrystal Figure S33. ORTEP diagram of TNT:phenothiazine cocrystal Figure S34. Simulated (bottom) and experimental (top) PXRD of TNT:phenothiazine cocrystal. 24

25 TNT:dibenzothiophene cocrystal Figure S35. ORTEP diagram of TNT:dibenzothiophene cocrystal Figure S36. Simulated (bottom) and experimental (top) PXRD of TNT:dibenzothiophene cocrystal. 25

26 TNT:4,6-dimethyldibenzothiophene cocrystal Figure S37. ORTEP diagram of TNT:4,6-dimethyldibenzothiophene cocrystal Figure S38. Simulated (bottom) and experimental (top) PXRD of TNT:4,6-dimethyldibenzothiophene cocrystal. 26

27 TNT:1,2-phenylenediamine cocrystal Figure S39. ORTEP diagram of TNT:1,2-phenylenediamine cocrystal Figure S40. Simulated (bottom) and experimental (top) PXRD of TNT:1,2-phenylenediamine cocrystal. 27

28 TNT:1,4-dimethoxybenzene cocrystal Figure S41. ORTEP diagram of TNT:1,4-dimethoxybenzene cocrystal Figure S42. Simulated (bottom) and experimental (top) PXRD of TNT:1,4-dimethoxybenzene cocrystal. 28

29 TNT:4-aminobenzoic acid 1:1 cocrystal Figure S43. ORTEP diagram of TNT:4-aminobenzoic acid 1:1 cocrystal Figure S44. Simulated (bottom) and experimental (top) PXRD of TNT:4-aminobenzoic acid 1:1 cocrystal. 29

30 TNT:4-aminobenzoic acid 1:2 cocrystal Figure S45. ORTEP diagram of TNT:4-aminobenzoic acid 1:2 cocrystal Figure S46. Simulated (bottom) and experimental (top) PXRD of TNT:4-aminobenzoic acid 1:2 cocrystal. 30

31 TNT:anthranilic acid 1:1 cocrystal Figure S47. ORTEP diagram of TNT:anthranilic acid 1:1 cocrystal Figure S48. Simulated (bottom) and experimental (top) PXRD of TNT:anthranilic acid 1:1 cocrystal. 31

32 TNT:anthranilic acid 1:2 cocrystal Figure S49. ORTEP diagram of TNT:anthranilic acid 1:2 cocrystal Figure S50. Simulated (bottom) and experimental (top) PXRD of TNT:anthranilic acid 1:2 cocrystal. 32

33 Table S3. Experimental PXRD peak positions ( ) and the relative intensity (%) of TNT cocrystals θ I/I0 2θ I/I0 2θ I/I0 2θ I/I0 2θ I/I0 2θ I/I0 2θ I/I0 2θ I/I0 2θ I/I

34 Table S4. Experimental PXRD peak positions ( ) and the relative intensity (%) of TNT cocrystals θ I/I0 2θ I/I0 2θ I/I0 2θ I/I0 2θ I/I0 2θ I/I0 2θ I/I0 2θ I/I

35 SI 5. References 1. Dorey, R. C.; Carper, W. R., J. Chem. Eng. Data 1987, 29, Henssler, J. T.; Matzger, A. J., Org. Lett. 2009, 11, Altomare, A.; Cascarano, G.; Giacovazzo, C.; Guagliardi, A., J. Appl. Crystallogr. 1994, 27, Burla, M. C.; Caliandro, R.; Camalli, M.; Carrozzini, B.; Cascarano, G. L.; De Caro, L.; Giacovazzo, C.; Polidori, G.; Spagna, R., J. Appl. Crystallogr. 2005, 38, Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman, W. P.; de Gelder, R.; Israel, R.; Smits, J. M. M. DIRDIF99; University of Nijmegen: The Netherlands, CrystalStructure, 3.8 ed.; Rigaku and Rigaku Americas: 9009 New Trails Dr., The Woodlands, TX USA, Sheldrick, G. M.; Schneider, T. R., Macromol. Crystallogr., Pt A 1997, 277,