N-Acyldithieno[3,2-b:2',3'-d]pyrroles: Second Generation Dithieno[3,2-b:2',3'-d]- pyrrole Building Blocks with Stabilized Energy Levels

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1 SUPPORTING INFORMATION N-Acyldithieno[3,2-b:2',3'-d]pyrroles: Second Generation Dithieno[3,2-b:2',3'-d]- pyrrole Building Blocks with Stabilized Energy Levels Sean J. Evenson and Seth C. Rasmussen* Department of Chemistry and Biochemistry, North Dakota State University, NDSU Dept. 2735, P.O. Box 6050, Fargo, ND USA. Fax: ; Tel: ; Table of Contents: I. General experimental details... S2 II. 3,3 -dibromo-2,2 -bithiophene (1)... S2 III. General procedure for the preparation of N-acyldithieno[3,2-b:2',3'-d]pyrroles... S2 IV. Table S1. Investigated catalytic conditions for the production of N-acylDTP 2b... S3 V. Figure S1. 1 H NMR spectrum of 2a... S4 VI. Figure S2. 13 C NMR spectrum of 2a... S4 VII. Figure S3. 1 H NMR spectrum of 2b... S4 VIII. Figure S4. 13 C NMR spectrum of 2b... S5 IX. Figure S5. 1 H NMR spectrum of 2c... S5 X. Figure S6. 13 C NMR spectrum of 2c... S5 XI. Figure S7. 1 H NMR spectrum of 2d... S6 XII. Figure S8. 13 C NMR spectrum of 2d... S6 XIII. Figure S9. 1 H NMR spectrum of 2e... S6 XIV. Figure S C NMR spectrum of 2e... S7 XV. X-ray Crystallography... S7 XVI. Figure S11. Ellipsoid Plots of 2b, 2d, and 2e at the 50% probability level... S7 XVII. Table S2. Crystal data, collection parameters, and refinement statistics for N-acylDTPs... S8 XVIII. UV-visible spectroscopy... S8 XIX. Electrochemistry... S9 XX. Calculations... S9 XXI. Figure S12. Calculated HOMO, LUMO, and LUMO+1 of N-acetyldithieno[3,2-b:2',3'-d]pyrrole.. S9 XXII. Table S3. Calculated atom coordinates and absolute energy of N-acetyldithieno- [3,2-b:2',3'-d]pyrrole... S10 XXIII. Table S4. Calculation of lowest energy electronic transition... S10 XXIV. References... S10 S1

2 General experimental details. Unless otherwise specified, all reactions were carried out under nitrogen atmosphere with reagent grade materials. THF and toluene were distilled from sodium/benzophenone prior to use. Chromatographic separations were performed using standard column methods with silica gel ( mesh). Melting points were determined using an digital thermocouple with a 0.1 C resolution. 1 H and 13 C NMR spectra were carried out on a 400 MHz spectrometer in CDCl 3. All NMR data was referenced to chloroform and peak multiplicity reported as follows: s = singlet, d = doublet, t = triplet, p = pentet, tt = triplet of triplets, m = multiplet, br = broad. 3,3 -dibromo-2,2 -bithiophene (1). To a 500mL-3-necked flask was added THF (200 ml), which was then cooled to 0 ºC. Diisopropylamine (3.1 ml, 22 mmol) was added, followed by n BuLi (8.8 ml, 22 mmol) and the mixture allowed to stir for 30 min. 3-Bromothiophene (1.87 ml, 20 mmol) was added and the solution was stirred for another 2 h. ZnCl 2 (2.998 g, 22 mmol) was added in one portion and stirred for 15 min. The solution was cooled to -78 ºC and CuCl 2 was added in one portion and stirred for 30 min. Dry O 2 was bubbled through the solution for 2 min and the reaction was stirred until completion (as monitored by TLC. ~1 h). The reaction was then warmed to room temperature and quenched with saturated aqueous NH 4 Cl (600 ml). The organic layer was separated and the aqueous layer was extracted with diethyl ether (2 x 200 ml). The combined organic layers were dried, filtered, concentrated via rotary evaporation, and purified by silica gel chromatography (hexanes) to give the isolated product as a white solid (2.86 g, 88%). mp ºC (lit C); 1 H NMR: 7.41 (d, J = 5.2 Hz, 2H), 7.08 (d, J = 5.2 Hz, 2H). 1 H NMR agree well with previously reported values. 1,2 General procedure for the preparation of N-acyldithieno[3,2-b:2',3'-d]pyrroles. To a 50mL-3 necked flask was added potassium carbonate (4.15 g, 30 mmol), DMEDA (0.216 ml, 2 mmol), copper iodide (0.095 g, 0.5 mmol), followed by evacuation and backfilling with nitrogen. Toluene (20 ml) was then added and the solution was allowed to stir for 30 min. Amide (12 mmol) was added, followed by 1 (3.24 g, 10 mmol), and the reaction was heated to just below reflux for 24 h. The reaction was then cooled to room temperature, quenched with water and extracted with hexane (3 x 20 ml). The combined organic layers were dried, filtered, concentrated via rotary evaporation, and purified by silica gel chromatography (1% hexane/ethyl acetate) to give the isolated product as a crystalline solid. N-Hexanoyldithieno[3,2-b:2',3'-d]pyrrole (2a). 24%; mp ºC; 1 H NMR: 7.49 (br s, 2H), 7.23 (d, J = 5.2 Hz, 2H), 3.00 (t, J = 7.6 Hz, 2H), 1.88 (p, J = 7.6 Hz, 2H), 1.45 (m, 4H), 0.96 (t, J = 7.6 Hz, 3H); 13 C NMR: 169.8, 142.4, 124.4, 122.1, 116.8, 36.6, 31.6, 24.1, 24.4, 22.8, 14.2; HRMS: m/z [M + Na] + (calcd for C 14 H 15 NNaOS ). N-Octanoyldithieno[3,2-b:2',3'-d]pyrrole (2b). 38%; mp ºC; 1 H NMR: 7.48 (br s, 2H), 7.22 (d, J = 5.2 Hz, 2H), 2.98 (t, J = 7.6 Hz, 2H), 1.87 (p, J = 7.6 Hz, 2H), 1.53 (m, 6H), 1.33 (m, 2H), 0.96 (t, J = 7.6 Hz, S2

3 3H); 13 C NMR: 169.8, 142.1, 124.5, 121.6, 116.4, 36.6, 31.9, 29.4(3), 29.3(5), 24.4, 22.8, 14.3; HRMS: m/z [M + Na] + (calcd for C 16 H 19 NNaOS ). N-Dodecanoyldithieno[3,2-b:2',3'-d]pyrrole (2c). 19%; mp ºC; 1 H NMR: 7.49 (br s, 2H), 7.24 (d, J = 5.2 Hz, 2H), 3.01 (t, J = 7.6 Hz, 2H), 1.88 (p, J = 7.6 Hz, 2H), 1.48 (m, 2H), 1.27 (m, 14H), 0.89 (t, J = 7.6 Hz, 3H); 13 C NMR: 169.8, 140.9, 124.6, 121.5, 116.9, 36.6, 32.2, 29.9, 29.7(3), 29.7(0), 29.6, 29.5, 24.4, 22.9, 14.4; HRMS: m/z [M + Na] + (calcd for C 20 H 27 NNaOS ). N-Benzoyldithieno[3,2-b:2',3'-d]pyrrole (2d). 36%; mp ºC; 1 H NMR: 7.73 (d, J = 8.4 Hz, 2H), 7.65 (t, J = 8.4 Hz, 1H), 7.54 (t, J = 8.4 Hz, 2H), 7.10 (d, J = 7.6 Hz, 2H), 6.86 (br s, 2H); 13 C NMR: 167.0, 143.1, 134.5, 132.4, 128.7, 124.4, 121.8, 116.4; HRMS: m/z [M + Na] + (calcd for C 15 H 9 NNaOS ). N-Cyclohexanoyldithieno[3,2-b:2',3'-d]pyrrole (2e). 24%; mp ºC; 1 H NMR: 7.48 (br s, 2H), 7.24 (d, J = 5.2 Hz, 2H), 3.17 (tt, J = 11.6, 3.2 Hz, 2H), 2.01 (m, 2H), 1.75 (m, 2H), 1.40 (m, 2H); 13 C NMR: 173.0, 141.1, 124.6, 121.3, 116.5, 43.7, 29.3, 25.9; HRMS: m/z [M + Na] + (calcd for C 15 H 15 NNaOS ). Table S1. Investigated catalytic conditions for the production of N-acylDTP 2b S 1 Br Br S + H 2 N O C 7 H 15 CuI, ligand base gentle reflux S O C 7 H 15 Entry Catalyst mol % Ligand mol % Base Equivalents Solvent Temp %Yield 1 CuI 5 DMEDA 20 K 2 CO 3 3 1,4-dioxane ~ CuI 5 DMEDA 20 K 3 PO 4 3 1,4-dioxane ~ CuI 10 1,2-DACH 10 K 3 PO 4 2 1,4-dioxane ~ CuI 5 DMEDA 20 K 2 CO 3 3 toluene ~ CuI 10 DMEDA 20 K 2 CO 3 3 toluene ~ CuI 20 DMEDA 20 K 2 CO 3 3 toluene ~ CuI 20 DMEDA 20 K 3 PO 4 3 toluene ~ CuI 2 x10 DMEDA 40 K 2 CO 3 3 toluene ~ CuI 5 DMEDA 20 K 2 CO 3 3 xylenes ~ Pd 2 dba Xphos 2.5 Cs 2 CO t BuOH ~ Pd 2 dba BINAP 10 Na t OBu 2.4 toluene ~110 0 N 2b S i Pr NH 2 1,2-DACH = DMEDA = NH HN Xphos = NH 2 Pr i i Pr PCy 2 S3

4 Figure S1. 1 H NMR spectrum of 2a Figure S2. 13 C NMR spectrum of 2a Figure S3. 1 H NMR spectrum of 2b S4

5 Figure S4. 13 C NMR spectrum of 2b Figure S5. 1 H NMR spectrum of 2c Figure S6. 13 C NMR spectrum of 2c S5

6 Figure S7. 1 H NMR spectrum of 2d Figure S8. 13 C NMR spectrum of 2d Figure S9. 1 H NMR spectrum of 2e S6

7 Figure S C NMR spectrum of 2e X-ray Crystallography. X-ray quality crystals of 2b, 2d, and 2e were grown by the slow evaporation of an hexane solution. The X-ray intensity data of the crystals were measured at 273 K on a CCD-based X-ray diffractometer system equipped with a Mo-target X-ray tube ( = Å) operated at 2000 W of power. The detector was placed at a distance of cm from the crystal. Frames were collected with a scan width of 0.3 in and exposure time of 10 s/frame and then integrated with the Bruker SAINT software package using an arrow-frame integration algorithm. The unit cell was determined and refined by least-squares upon the refinement of XYZ-centeroids of reflections above 20 (I). The structure was refined using the Bruker SHELXTL (Version 5.1) Software Package. The crystal data, data collection parameters, and refinement statistics are listed in Table S1. Full crystallographic data is included in the cif file. Figure S11. Ellipsoid Plots of 2b, 2d, and 2e at the 50% probability level. S7

8 Table S2. Crystal data, collection parameters, and refinement statistics for N-acylDTPs 2b 2d 2e Formula C 16 H 19 NOS 2 C 15 H 9 NOS 2 C15 H15 N O S2 Formula Weight Temperature (K) 273(2) 273(2) 273(2) Crystal System Monoclinic Monoclinic Triclinic Space Group P2(1)/c P2(1)/c P-1 a (Å) 8.070(3) (3) 8.321(3) b (Å) (5) (3) 8.994(3) c (Å) (8) (3) 9.073(3) α (º) (5) β (º) (8) (6) (5) γ (º) (5) V (Å 3 ) (12) (6) 674.3(4) Z d calc (g cm -3 ) μ (mm -1 ) Reflections collected Unique reflections 2433 [R int = ] 2204 [R int = ] 2787 [R int = ] Final R indices [I>2 (I)] R 1 = R 1 = R 1 = wr 2 = wr 2 = wr 2 = R indices (all data) a R 1 = R 1 = R 1 = wr 2 = wr 2 = wr 2 = Goodness-of-fit on F a R 1 = ( F o F c ) / F o, wr 2 = [ (w(f o 2 F c 2 ) 2 ) / (F o 2 ) 2 ] 1/2, Goodness-of-fit on F 2 = [ ( w(f o 2 F c 2 ) 2 / (n-p)] 1/2, where n is the number of reflections and p is the number of parameters refined. Electrochemistry. Electrochemical measurements were performed on a BAS 100B/W using a Pt disc working electrode and a Pt wire counter electrode. Solutions consisted of 0.1 M TBAPF 6 in CH 3 CN and were sparged with argon for 20 min prior to data collection and blanketed with argon during the experiment. All potentials are referenced to a Ag/Ag+ reference electrode (0.1 M AgNO 3 /0.1 M TBAPF 6 in CH 3 CN; V vs. SCE) 3 and internally standardized with ferrocene (51 mv vs. Ag/Ag + ). E HOMO values were determined in reference to ferrocene (5.1 ev vs. vacuum). 4 Polymer films of the 2b were grown via repetitive cycles of the monomer cyclic voltammogram (-1000 mv to 1000 mv) using either a Pt disc or ITO-coated glass slide as the working electrode. The polymer-coated electrode was then removed, washed with CH 3 CN and placed in a cell with a fresh electrolyte solution for electrochemical characterization. S8

9 UV-visible spectroscopy. UV-visible spectra were measured on a dual beam scanning spectrophotometer using samples prepared as dilute CH 3 CN solutions in 1 cm quartz cuvettes or as polymer thin films on ITOcoated glass slides. The E LUMO values were determined from the difference of the E HOMO and E HOMO-LUMO values. The E HOMO-LUMO and band gap values were determined from the absorption onset of the solution and solid-state data, respectively. Table S3. Full UV-visible Spectroscopy Data for N-AcylDTPs a DTP max (nm) (M -1 cm -1 ) onset (nm) DTP max (nm) (M -1 cm -1 ) onset (nm) 2a d (sh) (sh) (sh) (sh) b e (sh) (sh) (sh) (sh) c (sh) a In CH 3 CN. sh = shoulder. Calculations. All calculations were performed using Guassian 03. Geometry optimization and frequency calculation for N-acetylditheno[3,2-b:2,3 -d]pyrrole were performed via DFT methods utilizing a 6-31G* basis set and a B3LYP correlation/exchange functional. The resulting calculated geometry for the DTP core agreed well with the reported structural data. Molecular orbital surfaces were generated utilizing the Gaussview 3.0 program with an isovalue of Electronic transitions were predicted through TD-DFT calculations, again utilizing a 6-31G* basis set and a B3LYP correlation/exchange functional. Figure S12. Calculated HOMO, LUMO, and LUMO+1 of N-acetyldithieno[3,2-b:2',3'-d]pyrrole S9

10 Table S3. Calculated atom coordinates and absolute energy of N-acetyldithieno[3,2-b:2',3'-d]pyrrole Center Atomic Atomic Coordinates (Angstroms) Number Number Type X Y Z Energy (hartrees) Table S4. Calculation of lowest energy electronic transition Transition Contribution Energy (ev) Wavelength (nm) f HOMO LUMO HOMO LUMO REFERENCES 1. Meng, H.; Huang, W. J. Org. Chem. 2000, 65, Dahlmann, U.; Neidlein, R. Helvetica Chim. Acta 1996, 79, Larson, R. C.; Iwamoto, R. T.; Adams, R. N. Anal. Chim. Acta 1961, 25, Thompson, B. C.; Kim, Y.-G.; McCarley, T. D.; Reynolds, J. R. J. Am. Chem. Soc. 2006, 128, S10