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Supporting Information for:

Porphyrin nanofiber bundles from phase-transfer ionic self-assembly andtheir photocatalytic self-metallization

Zhongchun Wang1,2, Kuangchiu J. Ho3, Craig J. Medforth1, and John A. Shelnutt1,2,*1. Surface and Interface Sciences Department, Sandia National Laboratories, Albuquerque, NM 87185

2. Department of Chemistry, University of Georgia, Athens, GA 306023. Department of Chemistry, University of New Mexico, Albuquerque, NM 87106

Synthesis of porphyrin nanofiber bundles. Oxo-Sb(V) 5,10,15,20-tetraphenylporphyrin iodideand the sodium salts of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (free base and Cu(II),Ni(II), Ag(II), or Zn(II) complexes) were purchased from Frontier Scientific and used withoutfurther purification. Stock solutions were prepared in ultrapure water from a Barnstead Nanopurewater system or in dichloromethane (HPLC grade, Aldrich) and filtered through a 0.2-µm syringefilter to remove particles. The stock solutions were stored in the dark and used within two weeks.

In a typical reaction, 9 mL of an aqueous solution of [H2TPPS4]4- (105 �M) was added to 9mL of a dichloromethane solution of [SbOTPP]+ (315 �M) in a 20-mL glass scintillation vial.This mixture was vigorously shaken for 2 minutes and then stirred vigorously for 1 hour using amagnetic stirrer bar. After the stirring was stopped and phase separation occurred, strands of pinkmaterial immediately appeared in the organic phase. This material tended to float up to theinterface but could be dispersed in the organic phase by gentle swirling. The sample was thenstored in the dark at room temperature for further characterization.

When the reaction was repeated without shaking and stirring, pink strands were found to formnear the interface after about 30 minutes. This material is much larger in size (up to 1 micron inwidth and tens of microns in length) and has a wide range of widths and lengths (see Fig. S1).Repeating this procedure with 10-fold lower porphyrin concentrations increased the formationtime for the pink strands but did not appreciably change the dimensions of the material.

Characterization of porphyrin nanofiber bundles. Transmission electron microscopy (TEM)and energy-dispersive X-ray spectroscopy (EDX) were performed on a JEOL 2010 transmissionelectron microscope (200 keV). Scanning electron microscopy (SEM) was carried out on aHitachi S-5200 Nano Scanning Electron Microscope operating at 1 kV. The samples for TEManalysis were prepared by pipetting 5-25 µl of the nanofiber suspension onto standard holey-carbon-coated copper TEM grids (SPI Supplies, Φ 3 mm, catalogue # 3620C-MB). The excesssolvent was wicked away by a Kimwipe® tissue underneath the copper grid. The grids were airdried for at least 2 hours before being loaded into the vacuum chamber of the electronmicroscope. The samples for both TEM and SEM imaging were not subjected to any pre-treatments such as heavy-metal staining or metal/carbon coating. Samples on TEM grids wereobserved by SEM using a specially designed sample holder.

The fluorescence images were recorded using a Zeiss LSM510 META laser scanningmicroscope and a Zeiss fluorescence microscope with an Axioskop digital camera. UV-visibleabsorption spectra were obtained with a HP 8452A diode array spectrophotometer. The steady-state fluorescence measurements were carried out on a Varian Cary Eclipse fluorescencespectrometer. X-ray diffraction patterns were recorded on a Siemens D500 diffractometer usingNi-filtered Cu K� radiation with � = 1.5418 Å in �–2� scan mode.

The molar ratio of the two porphyrins in the porphyrin nanofiber bundles was measured byelemental analysis, UV-visible absorption spectroscopy (Fig. S3) and EDX (Fig. S4). The pinkmaterial was first separated from the organic phase by centrifugation or filtration and then rinsedtwice with dichloromethane. Elemental analysis calculated for 4 [SbOTPP]+ and 1 [H2TPPS4]4-

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(C220H138N20S4O16Sb4): C, 67.19; H, 3.54; N, 7.12; O, 6.51; S, 3.26; Sb, 12.38. Found C, 61.65;H, 3.51; N, 6.51; O, 10.77; S, 3.31; Sb, 11.60. The Sb:S ratio indicates 3.7 [SbOTPP]+ per[H2TPPS4]4-.

Self-metallization of the porphyrin nanofiber bundles. Potassium tetrachloroplatinate(II)(K2PtCl4; 99.99%), hydrogen tetrachloroaurate(III) (HAuCl4; 17 wt.% solution in dilutehydrochloric acid; 99.99%), L-ascorbic acid (99+%), ethylenediamine tetra-acetic acid (EDTA)(99+%), silver nitrate (99.9%), sodium thiosulfate (99+%), and thiourea (99+%) were purchasedfrom Aldrich and used without further purification. Gold(I) sodium thiosulfate (99.9%) waspurchased from Alfa Aesar and also used without further purification. All reactant solutions wereprepared using ultrapure water. Ascorbic acid is unstable in aerated water, so a stock solution (0.2M) was freshly prepared before each reaction. K2PtCl4 solution (20 mM) was prepared andequilibrated overnight before use (Ciacchi, L. C.; Pompe, W.; De Vit, A. J. Am. Chem. Soc. 2001,123, 7371). Gold(I) thiosulfate solution was freshly prepared before use and filtered through a 0.2�m membrane. Silver(I) thiosulfate solution was freshly prepared before use by dropwiseaddition of 2 ml of silver nitrate solution (0.1 M) to 8 ml of sodium thiosulfate solution (0.1 M).The solution was filtered through a 0.2 micron membrane prior to use. Au(I)-(thiourea)x solutionwas freshly prepared according to a published procedure (Wang, Z.; Medforth, C. J.; Shelnutt, J.A. J. Am. Chem. Soc. 2004, 126, 16720).

Since the porphyrin nanofiber bundles are not easily dispersed in aqueous solutions, theywere first immobilized by drying them onto standard holey-carbon coated TEM Cu grids; thisalso facilitates TEM or SEM imaging. For the photocatalytic metallization reactions, typically 20�L of a suspension of nanofiber bundles in dichloromethane prepared by the synthesis describedabove was pipetted onto a TEM grid, and the solvent was wicked away using a Kimwipe® tissueplaced underneath the grid. The TEM grid was submerged in a 2-mL glass vial containing 1 mLof a solution of the metal precursor(s) (typically 0.1 or 1.0 mM) and ascorbic acid or EDTA(typically 20 mM). The vial was placed in a glass water bath (for temperature control), and thenthe nanofiber bundles on the TEM grid were irradiated with incandescent light (800 nmol cm-2

s-1). After light exposure, the TEM grid was rinsed twice with deionized water prior to TEMimaging. Negligible amounts of gold or silver deposition were observed in control experimentswithout light or the porphyrin nanofiber bundles, confirming that these reactions arepredominantly photocatalytic.

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Supplementary Figure 1

Figure S1. SEM images (a and b) and conventional fluorescence image (c) of porphyrin rodsprepared from 105 �M [H2TPPS4]4- and 315 �M [SbOTPP]+ without shaking or stirring thereaction mixture: (a) The rods are up to 1 micron in width and tens of microns in length with awide size distribution (the background is the holey-carbon film on a TEM grid); (b) at highermagnification the rods are seen to consist of bundles of fibers ~30 nm in diameter; (c)conventional fluorescence image of the porphyrin rods.

2 �m

b

a

c

10 �m

50 �m

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Supplementary Figure 2

1 2 3 4 5 6 7 8 9 10 11

d =

1.0

nm

d =

2.1

nm

Inte

nsi

ty (

arb

. u.)

2� (degree)

Figure S2. (a) Low-angle X-ray diffraction pattern of the porphyrin nanofiber bundles; (b) High-resolution TEM image of a porphyrin nanofiber bundle showing layering along the fiber axis andthe minimum inter-lamellar spacing of ~2.2 nm.

70 nm2.2 nm

a

b

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Supplementary Figure 3

340 360 380 400 420 440 460

aA

bso

rba

nce

(a

. u

.)

Wavelength (nm)

Experimental Simulated

450 500 550 600 650 700

b

Ab

sorb

an

ce (

a.

u.)

Wavelength (nm)

Experimental Simulated

Figure S3. Simulation of the UV-visible spectrum of the porphyrin nanofiber bundles dissociatedin ethanol using the spectra of monomeric [SbOTPP]+ or [H2TPPS4]4- in ethanol: (a) Soret-bandregion, best fit ratio 4.0:1; (b) Q-band region, best fit ratio 3.5:1.

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Supplementary Figure 4

0 5 10 15 20Energy (keV)

0

1000

2000

3000

4000

Counts

C

O

Cu

S

Sb

Sb

Cu

Cu

Figure S4. Energy dispersive X-ray spectrometry (EDX) of the porphyrin nanofiber bundles.Signals from Cu are due to the copper TEM grid. The atomic ratio of Sb:S was found to be56.1:43.9, based on the L line of Sb and the K line of S, and averaged over the six differentmeasured areas. This atomic ratio corresponds to a ratio of 5.1:1.0 for [SbOTPP]+/[H2TPPS4]4-.Given that EDX is typically less sensitive to light elements such as sulfur, this ratio is close to thevalue of 4:1 expected for an ionic solid composed entirely of porphyrins.

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Supplementary Figure 5

300 400 500 600 700 8000.0

0.3

0.6

0.9

1.2

1.5422

554 594

516

552 580 632

414

[H2TPPS4]4- x 10

Abso

rba

nce

Wavelength (nm)

31.5 �M [SbOTPP]+ in dichloromethane

10.5 �M [H2TPPS4]4- in water

Figure S5. UV-visible spectra of monomeric [SbOTPP]+ and [H2TPPS4]4- solutions. The spectrawere measured using a 1-mm quartz cuvette, except for the expansion of the Q-band region of[H2TPPS4]4- which was measured using a 1-cm cuvette.

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Supplementary Figure 6

550 600 650 700 750

606 653

645

701

Inte

nsi

ty (

a. u.)

Wavelength (nm)

Figure S6. Emission spectra of monomeric solutions of [SbOTPP]+ in dichloromethane (blackcurve) and [H2TPPS4]4- in water (red curve) obtained with 420-nm excitation.

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Supplementary Figure 7

Figure S7. TEM images of platinized porphyrin nanofiber bundles showing various degrees of

coverage with platinum dendrites: (a) dense, but non-continuous; (b) virtually continuous. The

platinization was achieved by 6 minutes of light exposure in the presence of 20 mM ascorbic acid

and 0.1 mM K2PtCl4 (a) or 1.0 mM K2PtCl4 (b).

100 nm

100 nm

b

a

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Supplementary Figure 8

Figure S8. TEM image of porphyrin nanofiber bundles gilded by 8 minutes of light exposure in

the presence of 0.1 mM Au(I)-thiosulfate complex and 20 mM ascorbic acid.

70 nm

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Supplementary Figure 9

Figure S9. TEM image of porphyrin nanofiber bundles decorated with flattened silver

nanoparticles. The silver metallization was achieved by 8 minutes of light exposure in the

presence of 1.0 mM Ag(I)-thiosulfate complex and 20 mM ascorbic acid.

70 nm

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Supplementary Figure 10

Figure S10. TEM image of porphyrin nanofiber bundles prepared from [SbOTPP]+ and

[CuTPPS4]4- and platinized by 6 minutes of light exposure in the presence of 0.1 mM K2PtCl4 and

20 mM ascorbic acid.

100 nm