1

Determining the absorption tolerance of single chromophore photodiodes for machine vision

R. Jansen van Vuuren1, K. D. Johnstone1, S. Ratnasingam3, H. Barcena1,P. C. Deakin2, A. K. Pandey4, P. L. Burn1, S. Collins3, and I. D. W. Samuel4

1Centre for Organic Photonics & Electronics, The University of Queensland, 4072 Queensland, Australia

2Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Rd, OX1 3TA Oxford, UK

3Department of Engineering, University of Oxford, Parks Rd, OX1 3PJ Oxford, UK

4Organic Semiconductor Centre, School of Physics & Astronomy, SUPA, University of St Andrews, North Haugh, KY16 9SS Fife, UK

Supplementary Information

Simulation Details

The effect on feature F1 and F2 of a variety of phenomena including temporal noise, the effects of an analogue to digital converter and sensors that respond over a range of wavelengths, and the fact that the spectrum of daylight is not described by Wein’s approximation have been studied numerically1. The reflectance data of Munsell colors and the daylight spectra used in these studies were sampled at 1 nm intervals. The simulated response of eachsensor to a reflectance under different illumination conditions was obtained by integrating the product of the particular Munsell reflectance, the CIE standard daylight spectra and a function or data representing the spectral sensitivity of the sensors. To represent the effects of temporal noise the result of the integral was then multiplied by a normal distribution with a mean value of one and standard deviation of 0.01. The final step in the simulation was then to represent the effects of using an analogue to digital converter (ADC) to convert the sensor responses to digital quantities. In representing the quantiser effect the first stage is to determine the maximum sensor response. A white standard reflectance and the CIE standard daylight illuminant (6500 K) was used to determine this maximum response. This maximum sensor response was then divided by 210, to represent a 10 bit ADC.

A typical feature space obtained using 14 CIE standard daylights and 202 Munsell reflectances with similar relative brightness is shown in Figure S1. In this figure each cross represents the actual color of the Munsell reflectance when illuminating with one of the 14 CIE daylight spectra. This figure shows that as required most different colors are widely separated in the space and most similar colors are near neighbours. A closer inspection of the feature space shows that noise and a residual dependence on the spectrum of the illuminating light means that each of the Munsell reflectances creates a small cluster of responses in the feature space. The size of these clusters depends upon several factors including the width of the sensor responses, the amount of noise in the sensor responses and the difference between the spectrum of the light source and that of a blackbody. To determine the width of the sensor responses needed to obtain useful features a method has been proposed to determine the significance of the area occupied by each cluster1.

Figure S1: The two dimensional feature space formed with 80 nm FWHM equal weight sensors when applying 202 Munsell surfaces and 14 CIE standard daylights. Each cross is the color of the relevant Munsell color. In this case the sensor responses were represented using 10 bits.

The cluster of points formed by each of the Munsell reflectances when illuminating with CIE standard test daylights form a non-uniform distribution of points (see Figure S2). To account for this observed non-uniform distribution it is appropriate to use a distance metric which takes this non-uniform nature of cluster points into account. Therefore, the Mahalanobis distance was applied to determine a boundary that ideally encloses all points in each cluster of responses corresponding to the same Munsell reflectance. For n-dimensional normally distributed data, the Mahalanobis distance between the centre of the cluster C and a data point P is defined as:

where Σ is the covariance matrix of the distribution. For a pair of surface reflectances representing colors separated by a known distance in CIELab space the Mahalanobis distance can be used to determine a boundary around each cluster. To determine the Mahalanobis distance boundary of a particular reflectance pair the first step is to find the centre of each cluster of responses. Then the Mahalanobis distance from the centre of the respective clusters to the boundary was increased from a small value until the boundaries formed by both members of a pair touch each other. To assess the dependency of the feature space on the illuminant, the number of responses that fall inside the correct boundary in the pair was then counted.

Figure S2: The clusters of points formed by Munsell reflectances corresponding to colors that are good matches to each other. In this figure the colors have been chosen to allow the four constituent parts of the figure to be seen easily and have no significance. In particular the blue and red crosses are the features extracted from noisy responses to each of the two reflectances under different illuminants. The purple and the green are then the boundaries drawn around each of the clusters so that the boundaries just touch.

To assess the quality of the information that can be obtained from F1 and F2 the pairs of reflectances that are separated by six units in CIELab space have been used. In addition to being independent of the spectrum of the illuminant F1 and F2are also independent of the brightness of the illuminant. This means that they are also independent of the lightness of any color and are therefore related to the chromaticity of the color. To assess the feature space reflectances that differ only by chromaticity have been obtained by scaling the 1269 Munsell reflectance spectra so that all these scaled spectra have a luminance component in CIELab color space of 50 units. This particular value of the L component of CIELab was chosen because it is the middle of the range and possible L values and it is also used in defining the CIE standard color difference model (E94)2.Critically this scaling means that pairs of reflectance spectra can be selected that only differ by their chromaticity. From this normalised Munsell data a set of 100 pairs of reflectances that differ by between 5.995 to 6.005 CIELab units were chosen randomly. To assess the dependency of the feature space on the illuminator the number of responses that fall inside the correct boundary in the pair was then counted. This test was performed on all the 100 pairs of reflectances in the test data set and the percentage of points falling within the boundary was recorded.

Experimental Details

All solvents were distilled prior to use. N,N-Dimethylformamide was dried over calcium hydride, filtered, and distilled under reduced pressure. Tetrahydrofuran was freshly distilled over sodium and benzophenone. Column chromatography was performed with Kieselgel 60 230-400 mesh silica purchased from Merck (cat. number 1.09385.9025). 1H and 13C NMR spectroscopy was performed on Bruker Avance AV-300, AV-400 or AV-500 MHz spectrometers: spH = surface phenyl H; bpH = branch phenyl H; IndH = indolenyl H; ThH = thiophenyl H; cpH = cyclopentanone H. Coupling constants are given to the nearest 0.5 Hz and br = broad. UV-visible spectroscopy were performed on a Cary 5000 UV-Vis spectrophotometer as either a thin film on quartz or as a solution in spectroscopic grade solvent (sh = shoulder). FT-IR spectroscopy was performed on solid samples using a Perkin-Elmer Spectrum 100 FT-IR Spectrometer with ATR attachment. Melting points were determined using a Buchi B-545 melting point apparatus. Differential scanning calorimetry was performed with a Perkin-Elmer Diamond DSC.Microanalyses were performed on a Carlo Erba NA 1500 Elemental Analyser. Matrix-assisted laser-desorption ionisation time of flight (MALDI-TOF) mass spectrometry was performed on a Voyager DE STR MALDI-TOF spectrometer. Electrospray ionisation mass spectrometry was performed on a BRUKER HCT 3D Ion Trap mass spectrometer. Quartz substrates were cleaned by sonication at 80 °C with Alconox detergent (1g/100 mL in MilliQ water), then scrubbed using Kim-wipes before being sequentially sonicated at 50 °C in Alconox (1 g/100 mL in MilliQ water), MilliQ water, acetone, and 2-propanol. The substrates were dried under a stream of nitrogen immediately prior to spin-coating. Compounds were spin coated onto 2.5 cm x 2.5 cm square pre-cleaned quartz substrates using a Cookson Electronics G3-8 speciality coating system. Film thicknesses were determined using a Dektak 150 Profilometer.

5,5'''-Bis{3,5-bis[4-(2-ethylhexyloxy)phenyl]phenyl}-[2,2':5',2":5'',2''']-quaterthiophene (1)

5-Bromo-5'-{3,5-bis[4-(2-ethylhexyloxy)phenyl]phenyl}-[2,2’]-bithiophene3 (119 mg, 0.16 mmol), bis(pinacolato)diboron (41.4 mg, 0.16 mmol), potassium acetate (50 mg, 3 equiv.), and N,N-dimethylformamide (5 mL) were placed in a pressure tube. The mixture was freeze-pump-thaw degassed three times, then back-filled with nitrogen. Bis(triphenylphosphine)palladium(II) dichloride (6 mg, 8.2 μmol) was added under nitrogen and the mixture was freeze-pump-thaw degassed twice, then back-filled with nitrogen. The reaction mixture was stirred at 75 °C overnight. The reaction was allowed to cool to room temperature before being diluted with toluene (50 mL). The solution was washed with a saturated aqueous solution of sodium hydrogen carbonate (2 x 25 mL) and brine (30 mL), dried over anhydrous magnesium sulfate, filtered, and the solvent removed. The residue was purified using column chromatography over silica using dichloromethane:hexane mixtures (0:100 to 1:4) to yield 1 (63 mg, 30%) as a red-orange amorphous solid. Tg: 31 °C; Solution UV-vis (CH2Cl2): λmax(ε) 269 nm (4.1 x 105), 431 nm (2.9 x 105); Thin Film UV-vis (10 mg/mL spin-coated: toluene, 1500 rpm, 120 sec; film thickness = 30 nm): λmax 438 nm; 1H NMR (300 MHz, CDCl3) δ 0.91-0.99 (24 H, m, CH3), 1.32-1.63 (32 H, m, CH2), 1.78 (4 H, m, CH), 3.91 (8 H, m, ArOCH2), 7.02 and 7.60 (16 H, AA’BB’, spH), 7.10 (2 H, d, J = 4.0, ThH), 7.14 (2 H, d, J = 4.0, ThH), 7.18 (2 H, d, J = 4.0, ThH), 7.33 (2 H, d, J = 4.0, ThH), 7.64 (2 H, dd, J = 1.5, J = 1.5, bpH), 7.69 (4 H, d, J = 1.5, bpH); 13C NMR (100 MHz, CDCl3) δ 11.1, 14.1, 23.1, 23.9, 29.1, 30.5, 39.4, 70.6, 114.9, 122.4, 124.1, 124.3, 124.4, 124.6, 124.8, 128.2, 133.0, 134.7, 135.9, 136.36, 136.41, 142.2, 143.4, 159.3; MS (MALDI-TOF, m/z, dithranol) 1299.1 (100%) [M]+, Anal. Calcd for C84H98O4S4: C, 77.6; H, 7.6; S 9.9. Found: C, 77.5; H, 7.6; S 9.5.

5-{3,5-Bis[4-(2-ethylhexyloxy)phenyl]phenyl}-2,3,3-trimethyl-3H-indole

A mixture of 2-{3,5-bis[4-(2-ethylhexyloxy)phenyl]phenyl}-4,4,5,5-tetramethyl-1,3,2-dioxaborolane4(1.84 g, 3.01 mmol), 5-bromo-2,3,3-trimethyl-3H-indole5 (594 mg, 2.50 mmol), tetrakis(triphenylphosphine)palladium(0) (145 mg, 0.126 mmol), aqueous sodium carbonate (2 M, 7.0 ml), ethanol (10 mL) and toluene (18 mL) was deoxygenated by vacuum-nitrogen purging three times and then heated at reflux for 45 h. The mixture was allowed to cool and water (60 mL) and ether (60 mL) were added. The organic layer was removed and the aqueous layer was extracted with ether (2 x 100 mL). The organic layer and the ether extracts were combined, dried over anhydrous magnesium sulfate, filtered, and the solvent removed. The residue was purified by column chromatography over silica using ethyl acetate:light petroleum mixtures (1:4 to 1:1) as eluent to give 5-{3,5-bis[4-(2-ethylhexyloxy)phenyl]phenyl}-2,3,3-trimethyl-3H-indole(1.55 g, 97%) as a viscous yellow oil. UV-vis (THF): λmax(ε) 276 (1.8 x 105); 1H NMR (400 MHz, CDCl3) δ 0.90-0.97 (12 H, m, CH3), 1.32-1.60 (22 H, m, CH2 & C(CH3)2), 1.72-1.82 (2 H, m, CH), 2.34 (3 H, s, -NCH3), 3.91 (4 H, d, ArOCH2), 7.02 (4 H, 1/2AA’BB’, spH), 7.57 (1 H, m, IndH), 7.61-7.65 (6 H, m, spH & IndH), 7.69 (3 H, s, bpH); 13C NMR (100 MHz, CDCl3) δ 11.1, 14.1, 15.5, 23.1, 23.2, 23.9, 29.1, 30.5, 39.4, 53.8, 70.6, 114.9, 119.9, 120.5, 124.2, 127.0, 128.3, 133.5, 138.8, 142.0, 142.4, 146.2, 152.8, 159.18, 159.24, 188.6; MS (ESI+, m/z, DCM) 644.6 (100%) [MH]+; Anal. Calcd for C45H57NO2: C, 83.9; H, 8.9; N, 2.2. Found: C, 83.9; H, 9.1; N, 2.2.

5-{3,5-Bis[4-(2-ethylhexyloxy)phenyl]phenyl}-2,3,3-trimethyl-3H-indolium iodide

A mixture of 5-{3,5-bis[4-(2-ethylhexyloxy)phenyl]phenyl}-2,3,3-trimethyl-3H-indole(0.73 g, 1.1 mmol) and methyl iodide (0.8 mL, 12.8 mmol) in acetonitrile (2 mL) and tetrahydrofuran (2 mL) was deoxygenated by vacuum-nitrogen purging three times and then heated at reflux in the dark for 36 h. The mixture was then allowed to cool before the volatiles were removed in vacuo. Light petroleum (40 mL) was then added and the mixture stirred under ambient conditions in the dark for 45 min. The solvent was decanted and the residue dried, providing the product as dark green crystals (891 mg, quantitative). m.p. 116-118 °C; UV-vis (THF): λmax(ε) 276 (6.2 x 105); 1H NMR (300 MHz, CDCl3) δ 0.89-0.98 (12 H, m, CH3), 1.30-1.59 (16 H, m, CH2), 1.73-1.81 (8 H, m, CH & C(CH3)2), 3.15 (3 H, s, -NCH3), 3.90 (4 H, m, ArOCH2), 4.34 (3 H, s, -NCH3), 7.02 (4 H, 1/2AA’BB’, spH), 7.58-7.64 (6 H, spH & bpH), 7.73-7.77 (3 H, m, bpH & IndH), 7.86 (1 H, dd, J = 8, J = 1.5, IndH); 13C NMR (100 MHz, CDCl3) δ 11.1, 14.1, 17.0, 23.0, 23.3, 23.9, 29.1, 30.5, 37.3, 39.4, 54.7, 70.6, 115.0, 115.4, 122.0, 124.3, 125.5, 128.3, 128.7, 132.8, 140.2, 141.1, 142.0, 142.5, 144.2, 159.4, 195.6; MS (ESI+, m/z, 5% DCM/MeOH) 658.4 (100%) [M+], 784.2 (18%) [MI]+; Anal. Calcd for C46H60INO2: C, 70.3; H, 7.7; N, 1.8. Found: C,70.3; H, 7.8; N, 1.8.

5-{3,5-Bis[4-(2-ethylhexyloxy)phenyl]phenyl}-2,3,3-trimethyl-3H-indol-2-ylidene-acetaldehyde

5-{3,5-Bis[4-(2-ethylhexyloxy)phenyl]phenyl}-2,3,3-trimethyl-3H-indolium iodide (184 mg, 0.23 mmol) and potassium t-butoxide (80 mg, 0.71 mmol) were dissolved in tetrahydrofuran (5 mL) and stirred under nitrogen at ambient temperature for 2 h. The solvent was removed before water (50 mL) and ether (50 mL) were added. The organic layer was removed and the aqueous layer was extracted with ether (2 x 50 mL). The organic layer and the ether extracts were combined, dried over anhydrous magnesium sulfate, filtered, and the solvent removed to afford the enamine intermediate, which was used immediately without purification. Phosphorous oxychloride (0.3 mL, 3.2 mmol) was added dropwise with stirring to dry N,N,-dimethylformamide (0.4 mL) holding the temperature <10 °C under anhydrous conditions. A solution of the enamine in dry N,N,-dimethylformamide (0.2 mL) was then added to the mixture at this temperature, and the reaction was then heated at 35 °C for 45 min. Ice water (20 mL) was then added to the reaction mixture followed by a saturated aqueous sodium hydroxide solution (5 mL) until the pH of the mixture was approximately 10. The reaction mixture was then heated at reflux for 20 min. The mixture was allowed to cool before brine (30 mL) and ether (30 mL) were added. The organic layer was removed and the aqueous layer was extracted with ether (2 x 30 mL). The organic layer and the ether extracts were combined, dried over anhydrous magnesium sulfate, filtered, and the solvent removed. The crude product was purified using column chromatography over silica using ethyl acetate:light petroleum mixtures (1:19 to 1:1) as eluent to give the product as a pink amorphous solid (119 mg, 75%). m.p. 64-66 °C;UV-vis (THF): λmax(ε) 232 (4.7 x 104) 274 (4.7 x 104), 347 (4.2 x 104); FT-IR (solid) υ = 1634 (C=O) cm-1; 1H NMR (400 MHz, CDCl3) δ 0.90-0.98 (12 H, m, CH3), 1.31-1.60 (16 H, m, CH2), 1.72-1.82 (8 H, m, CH & C(CH3)2), 3.34 (3 H, s, -NCH3), 3.91 (4 H, m, ArOCH2), 5.50 (1 H, d, J = 9.0, vinylH), 6.97 (1 H, d, J = 8.0, IndH), 7.02 (4 H, 1/2AA’BB’, spH), 7.54 (1 H, d, J = 1.5, IndH), 7.60-7.64 (5 H, m, spH & IndH), 7.64 (2 H, d, J = 2.0, bpH), 7.69 (1 H, dd, J = 2.0,J = 2.0, bpH), 9.95 (1 H, d, J = 9.0 Hz); 13C NMR (100 MHz, CDCl3) δ 11.3, 14.2, 23.2, 24.0, 29.2, 29.8, 29.9, 30.7, 39.5, 47.7, 70.8, 99.5, 108.3, 115.0, 121.1, 124.0, 124.4, 127.4, 128.4, 133.5, 136.3, 140.3, 141.9, 142.3, 143.2, 159.4, 173.7, 186.7; MS (ESI+, m/z, MeOH) 686.0 (100%) [M+]; Anal. Calcd for C47H59NO3: C, 82.3; H, 8.7; N, 2.0. Found: C, 82.1; H, 8.8; N, 2.1.

2,5-Bis[2-(1,3,3-trimethyl-5-{3,5-bis[4-(2-ethylhexyloxy)phenyl]phenyl}indolin-2-ylidene)ethylidene]cyclopentanone (2)

A solution of 5-{3,5-bis[4-(2-ethylhexyloxy)phenyl]phenyl}-2,3,3-trimethyl-3H-indol-2-ylidene-acetaldehyde (284 mg, 0.41 mmol) and potassium t-butoxide (60 mg, 0.53 mmol) in dry tert-butanol (4.2 mL) was heated at reflux for 30 min. Cyclopentanone (20 L, 0.23 mmol) was added dropwise to the solution and the reaction mixture was stirred at reflux for 18 h before being cooled to room temperature and the solvent removed. The residue was purified by column chromatography over silica using ethyl acetate:hexanes mixtures (1:9 to 1:3) as eluent to give 2 (48 mg, 16%) as a gold/purple solid. Tg 98 °C; UV-vis (THF): λmax(ε) 272 (1.4 x 105), 340 (sh; 3.7 x 104), 356 (sh;2.81 x 104), 410 (sh;2.0 x 104), 439 (sh;1.7 x 104) 480 (sh; 5.6 x 104), 516 (9.1 x 104); Thin Film UV-vis (27 mg/mL, spin-coated: chlorobenzene, 2000 rpm, 60 secs; film thickness = 85 nm): λmax 529 nm; FT-IR (solid) υ= 1559 (C=O) cm-1; 1H NMR (400 MHz, CDCl3) 0.90-0.97 (24 H, m, CH3), 1.32-1.62 (16 H, m, CH2), 1.72-1.81 (32 H, m, CH & C(CH3)2), 2.77 (4 H, s, cpH), 3.27 (6 H, s, -NCH3), 3.91 (8 H, m, ArOCH2), 5.36 (2 H, d, J = 13.0, vinylH), 6.79 (2 H, br d,J = 8.0, IndH), 7.01 and 7.61 (16 H, AA’BB’, spH), 7.50 (2 H, br s, IndH), 7.54 (2 H, dd, J = 8.0, J = 1.5, IndH), 7.65 (6 H, bs, bpH), 7.76 (2 H, br d, J = 13, vinylH); MS (MALDI-TOF, m/z, dithranol) 1420.2 (100%) [M]+.

1,3,3-Trimethyl-5-[3,5-bis(4-tert-butylphenyl)phenyl]-2-(3-{1,3,3-trimethyl-5-[3,5-bis(4-tert-butylphenyl)phenyl]indolin-2-ylidene}prop-1-enyl)-3H-indolium iodide (3)6

Thin Film UV-vis (20 mg/mL, spin-coated: chloroform, 1000 rpm, 60 secs; film thickness = 110 nm): λmax 590 nm.

4-[(5-Bromo-1,3,3-trimethyl-3H-indolium-2-yl)methylene]-2-[(5-bromo-1,3,3-trimethylindolin-2-ylidene)methyl]-3-oxocyclobut-1-enolate

1-Butanol (40 mL) and toluene (40 mL) was added to 5-bromo-1,3,3-trimethyl-3H-indolium iodide7(1.50 g, 3.95 mmol) and squaric acid (214 mg, 1.88 mmol). Quinoline (0.468 mL, 3.95 mmol) was added, and the reaction mixture was heated at reflux with a Dean-Stark apparatus for at least 10 h. The solvents were removed and the residue was dissolved in chloroform (400 mL). The organic layer was washed with aqueous hydrochloric acid (3 M, 5 x 75 mL)and brine (75 ml) before being dried with anhydrous magnesium sulphate, filtering and removing the solvent togive a dark blue solid of 4-[(5-bromo-1,3,3-trimethyl-3H-indolium-2-yl)methylene]-2-[(5-bromo-1,3,3-trimethylindolin-2-ylidene)methyl]-3-oxocyclobut-1-enolate (1.05 g, 96%). m.p. 367-368 °C; UV-vis (CHCl3): λmax(ε) 269 (1.3 x 104), 283 (sh; 1.2 x 104), 348 (sh; 5.3 x 103), 590 (sh; 3.6 x 104), 641 (2.5 x 105); FT-IR υ = 1595 (C=O) cm-1; 1H NMR (300 MHz, CDCl3) δ 1.77 (12 H, broad s, CH3), 3.54 (6H, br s, NCH3), 5.92 (2 H, br s, vinylH), 6.87 (2 H, d, J = 9.0, IndH), 7.42-7.44 (4 H, m, IndH); MS (MALDI-TOF, m/z, dithranol) 582.51 (100%) [MH]+; Anal. Calcd for C28H26Br2N2O2: C, 57.75; H, 4.5; N, 4.8. Found: C, 57.5; H, 4.45; N, 4.7.

4-[(5-{3,5-Bis[4-(2-ethylhexyloxy)phenyl]phenyl}-1,3,3-trimethyl-3H-indolium-2-yl)methylene]-2-[(5-{3,5-bis[4-(2-ethylhexyloxy)phenyl]phenyl}-1,3,3-trimethylindolin-2-ylidene)methyl]-3-oxocyclobut-1-enolate (4)

A mixture of 4-[(5-bromo-1,3,3-trimethyl-3H-indolium-2-yl)methylene]-2-[(5-bromo-1,3,3-trimethylindolin-2-ylidene)methyl]-3-oxocyclobut-1-enolate (329 mg, 0.620 mmol), 3,5-bis[4-(2-ethylhexyloxy)phenyl)]phenylboronic acid8 (176 mg, 0.302 mmol),sodium carbonate (65.7 mg, 0.62 mmol), and tetrakis(triphenylphosphine)palladium(0) (17.5 mg, 15 mol) was degassed and backfilled with argon. Deoxygenated toluene (2 mL), water (330 L), and ethanol (330 L) were added, and then the reaction mixture was heated at reflux for at least 10 h. Chloroform (30 mL) was added and the mixture was washed with brine (30 mL). The organic layer was dried over anhydrous magnesium sulfate, filtered, and the solvent removed. The residue was purified by column chromatography over silica using chloroform:acetone mixtures (1:0 to 95:5) as eluent to give 4 as a dark blue solid (355 mg, 84%), m.p. 281-285 °C; UV-vis (CHCl3): λmax(ε) 271 (1.8 x 105), 334 (sh; 2.6 x 104), 367 (sh; 1.4 x 104), 608 (sh; 9.8 x 104), 658 (5.4 x 105); Thin Film UV-vis (5 mg/mL, spin-coated: chloroform, 3000 rpm, 60 secs film thickness = 40 nm): λmax 675 nm; FT-IR (solid) υ = 1599 (C=O) cm-1; 1H NMR (300 MHz, CDCl3) δ 0.91-0.99 (24 H, m, CH3), 1.22-1.60 (32 H, m, CH2), 1.72-1.94 (16 H, m and br s, CH & C(CH3)2), 3.63 (6 H, br s, NCH3), 3.92 (8 H, m, ArOCH2), 5.99 (2 H, br s, vinylH), 7.04 (8 H, 1/2AA’BB’, spH), 7.10 (2 H, d, J =9, IndH), 7.61-7.72 (18 H, m, bpH, spH, & IndH); MS (MALDI-TOF, m/z, dithranol matrix) 1393.2 (100%) [M]+; Anal. Calcd for C96H116N2O6: C, 82.7; H, 8.4; N, 2.0. Found: C, 82.6; H, 8.6; N, 2.0.

References

1S. Ratnasingham and S. Collins, J. Opt. Soc. Am. A 27 (2), 286-294 (2010).

2H. C. Lee, Introduction to Color Imaging Science, Cambridge University Press,(2005).

3E. J. Wren, K. Mutkins, M. Aljada, P. L. Burn, P. Meredith, G. Vamvounis, submitted.

4 S.C. Lo, E.B. Namdas, P.L. Burn and I.D.W. Samuel,Macromolecules 36 (26), 9721-9730 (2003).

5M.V. Reddington, Bioconjugate Chemistry18 (6), 2178-2190 (2007).

6A. K. Pandey, P. C. Deakin, R. Jansen Van Vuuren, P. L. Burn, I. D.W. Samuel, Adv. Mater., 2010, in press.

7The indolium salt was prepared by the conventional reaction of the corresponding 2,3,3-trimethylindolinine derivatives with methyl iodide. See S. Yagi, K. Maeda, H. Nakazumi, J. Mater. Chem. 9, 2991-2997 (1999).

8Y.-J. Pu, R. E. Harding, S. G. Stevenson, E. B. Namdas, C. Tedeschi, J. P. J. Markham, R. J. Rummings, P. L. Burn, I. D. W. Samuel,J. Mater. Chem. 17,4255-4264 (2007).