Chem Commun ESI Bernhard - RSC

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Enhanced Photocatalytic Water Reduction by Cyclometalated Ir(III) 4-

Vinyl-2,2’-bipyridine Complexes

Stefan Metz and Stefan Bernhard

Department of Chemistry, 4400 Fifth Ave, Carnegie Mellon University,

Pittsburgh, PA 15213

Supporting Information

Experimental Section ......................................................................................................... S2

UV-VIS Spectra ................................................................................................................. S11

Emission Spectra ................................................................................................................ S14

Water Reduction Experiments ........................................................................................... S17

References .......................................................................................................................... S20

Supplementary Material (ESI) for Chemical CommunicationsThis journal is (c) The Royal Society of Chemistry 2010

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Experimental Section

General Procedures. 1H and 13C NMR spectra were recorded on a Bruker Avance 300 MHz

spectrometer with [D6]-acetone as the solvent (1H, δ = 2.05 ppm; 13C, δ = 29.9 ppm). Mass

spectral (MS) data were collected on a Hewlett-Packard 5898B electrospray engine. UV-VIS

spectra were recorded using a Varian Cary 50 spectrophotometer with 20 μM solutions in

THF/H2O (8/1). Emission spectra were recorded using a Jobin-Yvon Fluorolog-3

spectrometer equipped with double monochromators and a Hamamatsu-928 photomultiplier

tube at right-angle geometry. 20 μM solutions in THF/H2O (8/1) were prepared for lifetime

measurements and were degassed by bubbling with THF-saturated argon for 10 min. Lifetime

data were recorded using a Tektronix TDS 3032B digital phosphor oscilloscope after

excitation at 337 nm with a Laser Science VSL-337LRF N2 laser using a 10 ns pulse, and

emission quantum yields (Φem) were calculated relative to a [Ir(ppy)2bpy]PF6 reference (20

μM solution in acetonitrile; Φr=0.0622). Cyclic voltammetry (CV) was performed on a CH-

Instruments Electrochemical Analyzer 600C potentiostat using a 1 mm2 platinum disk

working electrode, a coiled platinum wire supporting electrode, and a silver wire as a

pseudoreference electrode. Ferrocene was employed as an internal standard, and its Fe(II/III)

half-wave potential was taken to be 370 mV against the standard calomel electrode (SCE).

The 500 μM solutions were prepared in acetonitrile containing 0.1 M tetra-n-butylammonium

hexafluorophosphate. The samples were degassed by bubbling argon into the solution for 10

min before the voltammograms were recorded at a 100 mV/s sweep rate.

Hydrogen Evolution Experiments. Samples were prepared in 40 mL precleaned screw cap

vials through the addition of 1.00 mL of a 500 µM photosensitizer (PS) stock solution in

acetone that was subsequently concentrated to dryness under reduced pressure. To this PS

charged vial was added 9 mL of a THF/triethylamine (8/1) mixture, followed by 1 mL of a

375 µM K2PtCl4 solution in H2O or a 375 µM [Rh(bpy)2Cl2]Cl solution in H2O. Each sample

was capped with a custom-built lid containing a voltage–pressure transducer (Omega PX-138-

030A5 V). The transducers have an operating range of 0–30 psi and were driven in parallel at

8 V using a variable power supply (Tenma 72–6152). The samples were deoxygenated

through four iterations of applying a vacuum and subsequently backfilling with argon. The

samples were placed in a 16-sample photoreactor that was illuminated from the bottom by

Luxeon V Dental Blue LEDs (LXHL-LRD5) that were driven two in a series at 700mA using

Xitanium drivers (Advance LED120A0700C24F). The LEDs had a maximum emission of

460 nm with a 20 nm fullwidth at half-maximum (fwhm) and were mounted with collimating


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optics (Fraen FHS-HNB1-LL01-H) to give 500 ± 50 mW of power to the individual samples.

Each LED was affixed to a copper plate that was situated on a water-cooled aluminium block,

and the entire setup was agitated at 150 rpm using an orbital shaker (IKA KS 260). During

illumination, the temperature of the samples was kept at 25 °C by using a water-cooled

sample block. Pressure data were collected every 30 s using a PC interface designed in

LabView. Pressure changes due to thermal fluctuations were monitored using a reference vial

that contained only the reaction solvent mixture, and these slight variations were subtracted

from the pressure traces of the samples. Analysis of the gases was performed using a

Hamilton SampleLock syringe and a Standard Research System QMS Series Gas Analyzer

that was calibrated using reference standards of 1:9 H2/Ar and 3:7 H2/Ar (Airgas).

Hydrogen production was calculated according to the ideal gas law assuming 1 atm, 298 K,

and a combined vial and transducer adapter headspace that was measured to be 35 mL. PS

turn-over numbers (TONs) refer to the total number of one-electron proton reductions

achieved by the time hydrogen evolution had ceased divided by the quantity of PS contained

in the initial reaction mixture.

Synthesis of 5-“R”-2-(4-“R*”-phenyl)pyridine

Except for 2,5-diphenylpyridine, all compounds were synthesized according to literature

procedures.1

Synthesis of 2,5-diphenylpyridine

This compound was synthesized according to the general procedure of ref 2. A mixture of 2,5-

dibromopyridine (1.00 g, 4.22 mmol), benzeneboronic acid (1.29 g, 10.6 mmol), potassium

phosphate (3.58 g, 16.9 mmol), and palladium(II) acetate (28 mg, 125 µmol) in water (5 mL)

and isopropanol (15 mL) was stirred at 80 °C for 90 min. Brine (25 mL) was added, and the

organic phase was extracted four times with ethyl acetate (25 mL each). The combined

organic phases were dried over sodium sulfate, and the solvent was removed under reduced

pressure. Hexanes (25 mL) was added to the remaining solid, the suspension was sonicated,

and the solid was isolated by filtration to give pure 2,5-diphenylpyridine in 79% yield (770

mg, 3.33 mmol). The analytical data were in accordance with the literature.3

Synthesis of 4-(2-hydroxyethyl)-4’-methyl-2,2’-bipyridine

This compound was prepared according to literature by lithiation of 4,4’-dimethyl-2,2’-

bipyridine with LDA followed by reaction with paraformaldehyde.4


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Synthesis of 4-vinyl-4’-methyl-2,2’-bipyridine

Potassium tert-butoxide (1.30 g, 11.6 mmol) was added at –10°C to a solution of 4-(2-

hydroxyethyl)-4’-methyl-2,2’-bipyridine (1.00 g, 4.67 mmol) in THF (25 mL). A solution of

p-toluenesulfonyl chloride (1.10 g, mmol) in THF (20 mL) was added within 15 min, and the

resulting mixture was stirred for 2 h. The reaction mixture was then poured into a

halfsaturated aqueous solution of sodium bicarbonate (30 mL) and extracted three times with

Et2O (30 mL each). The combined organic layers were dried over sodium sulfate, and the

solvent was removed under reduced pressure. The residue was purified by column

chromatography (silica; eluent, CH2Cl2 containing 3% NEt3) followed by crystallization from

hot hexanes. Yield: 830 mg (4.23 mmol, 91%) of a colorless solid. The analytical data were in

accordance with the literature.5

Synthesis of 4,4’-bis(2-hydroxyethyl)-2,2’-bipyridine

This compound was prepared according to literature by twofold lithiation of 4,4’-dimethyl-

2,2’-bipyridine with LDA followed by reaction with paraformaldehyde.6

Synthesis of 4,4’-divinyl-2,2’-bipyridine

Potassium tert-butoxide (51 mg, 454 µmol) was added at –20°C to a solution of 4,4’-bis(2-

hydroxyethyl)-2,2’-bipyridine (55 mg, 225 µmol) in a mixture of THF (10 mL) and CH2Cl2

(10 mL). Methanesulfonyl chloride (59 mg, 515 µmol) was added, and the resulting mixture

was stirred for 5 min, followed by addition of potassium tert-butoxide (60 mg, 535 µmol).

The mixture was stirred for a further 30 min at –20 °C, poured into a half-saturated aqueous

solution of sodium bicarbonate (10 mL), and extracted three times with CH2Cl2 (10 mL each).

The combined organic layers were dried over sodium sulfate, and the solvent was removed

under reduced pressure. The residue was purified by column chromatography (silica; eluent,

EtOAc/hexanes, 1:1, containing 3% NEt3) yielding 73% of a colorless solid (34 mg, 163

µmol). The analytical data were in accordance with the literature.7

Synthesis of tetrakis-(5-“R”-2-(4-“R*”-phenyl)pyridine)-bis-(µ-chloro)-diiridium(III)

These compounds were prepared according to literature procedures by reaction of two molar

equivalents of 5-“R”-2-(4-“R*”-phenyl)pyridine with one molar equivalent Iridium(III)

chloride hydrate in 2-methoxyethanol/water (5:1) at 120 °C for 16 h.1


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Synthesis of [(4,4’-dimethyl-2,2’-bipyridine)-bis-(C^N)-iridium(III)] hexafluoro-

phosphate

Except for C^N = 2,5-diphenylpyridine, all compounds were already described in literature.1

Synthesis of [(4,4’-dimethyl-2,2’-bipyridine)-bis-(2,5-diphenylpyridine)-iridium(III)]

hexafluorophosphate

A mixture of the appropriate iridium dimer (50.0 mg, 36.3 µmol; R = Ph, R* = H) and 4,4’-

dimethyl-2,2’-bipyridine (14.2 mg, 77.1 µmol) in CH2Cl2 (10 mL) and methanol (6 mL) was

stirred at 55 °C for 16 h. After cooling to room temperature, the CH2Cl2 was removed under

reduced pressure, and water (5 mL) was added to the residue. Ammonium

hexafluorophosphate (75 mg, 460 µmol) in water (2 mL) was added, and the resulting

suspension was stirred for 5 min. The solid was isolated by filtration and then washed with

water followed by hexanes. The obtained solid was dissolved in CH2Cl2 and crystallized by

ether diffusion to give a yellow solid in 84% yield (60 mg, 61.1 µmol). 1H NMR: δ = 8.71 (“br” s, 2H), 8.24–8.34 (m, 4H), 8.06 (d, J = 5.6 Hz, 2H), 7.94 (dd, J = 7.8

and 1.1 Hz, 2H), 7.88 (dd, J =2.0 and 0.7 Hz, 2H), 7.59 (ddd, J = 5.6, 1.0, and 0.6 Hz, 2H),

7.35–7.43 (m, 10H), 7.06 (dt, 7.6 and 1.2 Hz, 2H), 6.93 (dt, J = 7.4 and 1.3 Hz, 2H), 6.48 (dd,

J = 7.6 and 0.8 Hz, 2H), 2.60 (s, 6H).

High-resolution MS: Calcd for C46H36IrN4 [M+], m/z 837.2571; found, 837.2043.

Synthesis of [(4-vinyl-4’-methyl-2,2’-bipyridine)-bis-(5-methyl-2-(4-fluorophenyl)-

pyridine)iridium(III)] hexafluorophosphate

A mixture of the appropriate iridium dimer (40.0 mg, 33.3 µmol; R = Me, R* = F) and 4-

vinyl-4’-methyl-2,2’-bipyridine (13.7 mg, 69.8 µmol) in CH2Cl2 (10 mL) and methanol (6

mL) was stirred at 55 °C for 16 h. After cooling to room temperature, the CH2Cl2 was

removed under reduced pressure, and water (10 mL) was added to the residue. Ammonium




ether diffusion to give a yellow solid in 75% yield (45 mg, 49.7 µmol). 1H NMR: δ = 8.86 (d, J = 1.5 Hz, 1H), 8.78 (s, 1H), 8.11 (d, J = 8.4 Hz, 2H), 8.03 (d, J = 5.7

Hz, 1H), 7.90–7.96 (m, 3H), 7.79–7.84 (m, 2H), 7.66–7.74 (m, 2H), 7.53–7.62 (m, 2H), 6.96

(dd, J = 17.6 and 10.9 Hz, 1H), 6.79 (ddt, J = 8.5, 2.6, and 0.8 Hz, 2H), 6.43 (d, J = 17.6 Hz,


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1H), 5.94 (ddd, J = 9.6, 3.6, and 2.6 Hz, 2H), 5.77 (d, J = 10.9 Hz, 1H), 2.60 (s, 3H), 2.14 (s, 3

H), 2.13 (s, 3H). 13C NMR: δ = 165.1, 164.4 (d, 1JCF = 252 Hz), 157.5, 156.6, 154.1, 153.2, 151.7, 151.0, 149.6

(d, 3JCF = 7.5 Hz), 149.1, 141.7, 140.8, 134.9, 134.3, 130.3, 127.6 (d, 3JCF = 9.1 Hz), 126.7,

126.0, 123.7, 122.7, 120.5, 118.3 (d, 2JCF = 18 Hz), 110.3 (d, 2JCF = 23 Hz), 21.5, 18.0.

High-resolution MS: Calcd for C37H30F2IrN4 [M+], m/z 761.2070; found, 761.1976.

Synthesis of [(4-vinyl-4’-methyl-2,2’-bipyridine)-bis-(5-methyl-2-(4-chlorophenyl)-


A mixture of the appropriate iridium dimer (50.0 mg, 39.5 µmol; R = Me, R* = Cl) and 4-







ether diffusion to give a yellow solid in 81% yield (60 mg, 63.9 µmol). 1H NMR: δ = 8.88 (d, J = 1.5 Hz, 1H), 8.79 (s, 1H), 8.17 (d, J = 8.4 Hz, 2H), 8.04 (d, J = 5.8

Hz, 1H), 7.97 (d, J = 5.6 Hz, 1H), 7.81–7.90 (m, 4H), 7.72–7.75 (m, 2H), 7.63–7.65 (m, 1H),

7.55 (ddd, J = 5.6, 1.6, and 0.6 Hz, 1H), 7.06 (ddd, J = 8.3, 2.1, and 0.9 Hz, 2H), 6.97 (dd, J =

17.6 and 11.0 Hz, 1H), 6.43 (d, J = 17.6 Hz, 1H), 6.23 (dd, J = 3.7 and 2.1 Hz, 2H), 5.79 (d, J

= 11.0 Hz, 1H), 2.61 (s, 3H), 2.14 (s, 3 H), 2.13 (s, 3H). 13C NMR: δ = 164.9, 157.5, 156.6, 153.3, 152.8, 152.7, 151.7, 151.0, 149.74, 149.65, 149.2,

144.2, 144.1, 140.9, 136.0, 135.5, 134.3, 131.9, 130.3, 126.9, 126.7, 126.1, 123.7, 123.6,

122.7, 120.9, 21.5, 18.1.

High-resolution MS: Calcd for C37H30Cl2IrN4 [M+], m/z 793.1480; found, 793.1064.

Synthesis of [(4,4’-divinyl-2,2’-bipyridine)-bis-(5-methyl-2-(4-chlorophenyl)pyridine)-

iridium(III)] hexafluorophosphate

A mixture of the appropriate iridium dimer (29.0 mg, 22.9 µmol; R = Me, R* = Cl) and 4,4’-

divinyl-2,2’-bipyridine (10.0 mg, 48.0 µmol) in CH2Cl2 (5 mL) and methanol (3 mL) was





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water followed by hexanes. Acetone was added to the solid, and the undissolved residue was

filtered off. The solvent of the filtrate was removed, and the residue was dissolved in CH2Cl2

and then crystallized by ether diffusion to give an orange solid in 73% yield (32 mg, 33.7

µmol). 1H NMR: δ = 8.92 (d, J = 1.5 Hz, 2H), 8.16 (d, J = 8.4 Hz, 2H), 8.05 (d, J = 5.8 Hz, 2H), 7.88

(d, J = 8.4 Hz, 2H), 7.83 (ddd, J = 8.4, 1.9, and 0.6 Hz, 2H), 7.72–7.76 (m, 4H), 7.06 (dd, J =

8.3 and 2.1 Hz, 2H), 6.97 (dd, J = 17.6 and 11.0 Hz, 2H), 6.40 (d, J = 17.6 Hz, 2H), 6.24 (d,

2.1 Hz, 2H), 5.78 (d, J = 11.0 Hz, 2H), 2.13 (s, 6H). 13C NMR: δ = 164.8, 157.4, 152.7, 151.7, 149.8, 149.2, 144.1, 140.9, 136.0, 135.5, 134.3,

131.9, 126.9, 126.1, 123.8, 123.7, 123.0, 120.9, 18.1.

High-resolution MS: Calcd for C38H30Cl2IrN4 [M+], m/z 805.1480; found, 805.1144.

Synthesis of [(4-vinyl-4’-methyl-2,2’-bipyridine)-bis-(5-methyl-2-(4-methoxyphenyl)-


A mixture of the appropriate iridium dimer (50.0 mg, 40.1 µmol; R = Me, R* = OMe) and 4-







ether diffusion to give an orange solid in 72% yield (54 mg, 29.0 µmol). 1H NMR: δ = 8.85 (d, J = 1.4 Hz, 1H), 8.75 (s, 1H), 8.04 (d, J = 5.8 Hz, 1H), 7.95–8.00 (m,

3H), 7.79 (d, J = 8.6 Hz, 2H), 7.68–7.73 (m, 3H), 7.59–7.62 (m, 1H), 7.50–7.54 (m, 2H), 6.96

(dd, J = 17.6 and 11.0 Hz, 1H), 6.62 (ddd, J = 8.6, 2.6, and 0.8 Hz, 2H), 6.40 (d, J = 17.6 Hz,

1H), 5.82 (dd, J = 3.5 and 2.6 Hz, 2H), 5.77 (d, J = 11.0 Hz, 1H), 3.58 (s, 3H), 3.57 (s, 3H),

2.59 (s, 3H), 2.104 (s, 3 H), 2.096 (s, 3H). 13C NMR: δ = 166.2, 161.9, 157.6, 156.6, 153.3, 153.2, 152.8, 151.6, 150.9, 149.1, 149.0,

148.8, 140.2, 138.0, 134.4, 133.2, 130.1, 127.0, 126.5, 125.9, 123.4, 122.5, 119.6, 118.1,

108.2, 55.0, 21.5, 17.9.

High-resolution MS: Calcd for C39H36IrN4O2 [M+], m/z 785.2469; found, 785.2045.


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Synthesis of [(4-vinyl-4’-methyl-2,2’-bipyridine)-bis-(5-methyl-2-phenylpyridine)-

iridium(III)] hexafluorophosphate

A mixture of the appropriate iridium dimer (50.0 mg, 44.3 µmol; R = Me, R* = H) and 4-

vinyl-4’-methyl-2,2’-bipyridine (18.3 mg, 93.2 µmol) in CH2Cl2 (5 mL) and methanol (3 mL)

was stirred at 55 °C for 4 h. After cooling to room temperature, the CH2Cl2 was removed

under reduced pressure, and water (5 mL) was added to the residue. Ammonium




ether diffusion to give an orange solid in 84% yield (65 mg, 74.7 µmol). 1H NMR: δ = 8.85 (d, J = 1.5 Hz, 1H), 8.76 (s, 1H), 8.11 (d, J = 8.4 Hz, 2H), 7.98 (d, J = 5.3

Hz, 1H), 7.90 (d, J = 5.6 Hz, 1H), 7.77–7.84 (m, 4H), 7.68–7.71 (m, 2H), 7.59–7.61 (m, 1H),

7.51 (dq, J = 5.6 and 0.7 Hz, 1H), 6.94–7.02 (m, 3H), 6.84–6.91 (m, 2H), 6.40 (d, J = 17.6 Hz,

1H), 6.34 (ddd, J = 7.5, 3.8, and 0.8 Hz, 2H), 5.77 (d, J = 11.0 Hz, 1H), 2.59 (s, 3H), 2.15 (s, 3

H), 2.14 (s, 3H). 13C NMR: δ = 164.3, 157.6, 156.7, 152.8, 151.5, 151.1, 151.0, 155.8, 149.5, 149.4, 148.8,

145.20, 145.16, 140.3, 134.7, 134.4, 132.6, 130.8, 130.1, 126.5, 125.9, 125.4, 123.4, 122.5,

120.3, 21.5, 18.0.


Synthesis of [(4,4’-divinyl-2,2’-bipyridine)-bis-(5-methyl-2-phenylpyridine)iridium(III)]

hexafluorophosphate

A mixture of the appropriate iridium dimer (30.0 mg, 26.6 µmol; R = Me, R* = H) and 4,4’-

divinyl-2,2’-bipyridine (11.6 mg, 55.7 µmol) in CH2Cl2 (5 mL) and methanol (3 mL) was







and then crystallized by ether diffusion to give an orange-red solid in 64% yield (30 mg, 34.0

µmol). 1H NMR: δ = 8.93 (d, J = 1.5 Hz, 2H), 8.12 (d, J = 8.4 Hz, 2H), 8.00 (d, J = 5.8 Hz, 2H), 7.84

(dd, J = 7.7 and 1.2 Hz, 2H), 7.79 (ddd, J =8.4, 2.0, and 0.6 Hz, 2H), 7.71 (dd, J = 5.8 and 1.7


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Hz, 2H), 7.69–7.71 (m, 2H), 6.85–7.04 (m, 6H), 6.40 (d, J = 17.6 Hz, 2H), 6.34 (dd, J = 7.6

and 0.8 Hz, 2H), 5.77 (d, J = 11.0 Hz, 2H), 2.13 (s, 6H). 13C NMR: δ = 166.2, 157.5, 151.4, 151.0, 149.6, 148.9, 145.2, 140.4, 134.8, 134.4, 132.6,

130.8, 125.9, 125.4, 123.5, 123.3, 122.8, 120.4, 18.0.


Synthesis of [(4-vinyl-4’-methyl-2,2’-bipyridine)-bis-(2-phenylpyridine)iridium(III)]

hexafluorophosphate

A mixture of the appropriate iridium dimer (50.0 mg, 46.6 µmol; R = H, R* = H) and 4-vinyl-

4’-methyl-2,2’-bipyridine (19.2 mg, 97.8 µmol) in CH2Cl2 (10 mL) and methanol (6 mL) was






ether diffusion to give a yellow-orange solid in 88% yield (69 mg, 40.9 µmol). 1H NMR: δ = 8.88 (d, J = 1.6 Hz, 1H), 8.78 (s, 1H), 8.23 (d, J = 8.0 Hz, 2H), 7.81–8.00 (m,

8H), 7.72 (dd, J = 5.8 and 1.7 Hz, 1H), 7.53 (ddd, J = 5.6, 1.7, and 0.7 Hz, 1H), 7.12–7.19 (m,

2H), 6.99–7.06 (m, 2H), 6.88–6.97 (m, 3H), 6.40 (d, J = 17.6 Hz, 1H), 6.35 (ddd, 7.5, 3.0, and

0.8 Hz, 2H), 5.77 (d, J = 11.0 Hz, 1H), 2.59 (s, 3H). 13C NMR: δ = 168.8, 157.6, 156.6, 153.0, 151.74, 151.65, 151.5, 150.8, 150.2, 150.1, 149.0,

145.0, 139.5, 134.3, 132.6, 131.3, 130.2, 126.6, 125.9, 124.5, 123.5, 123.4, 122.6, 120.8, 21.4.


Synthesis of [(4-vinyl-4’-methyl-2,2’-bipyridine)-bis-(2,5-diphenylpyridine)iridium(III)]

hexafluorophosphate

A mixture of the appropriate iridium dimer (50.0 mg, 36.3 µmol; R = Ph, R* = H) and 4-









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and then crystallized by ether diffusion to give a yellow-orange solid in 72% yield (52 mg,

52.3 µmol). 1H NMR: δ = 8.89 (d, J = 1.5 Hz, 1H), 8.79 (s, 1H), 8.34 (d, J = 8.6 Hz, 2H), 8.26 (dt, J = 8.6

and 1.9 Hz, 2H), 8.15 (d, J = 5.8 Hz, 1H), 8.07 (d, J = 5.7 Hz, 1H), 7.88–7.97 (m, 4H), 7.79

(dd, J = 5.8 and 1.8 Hz, 1H), 7.60 (ddd, J = 5.7, 1.7, and 0.7 Hz, 1H), 7.36–7.43 (m, 10H),

6.91–7.09 (m, 5H), 6.49 (ddd, J = 7.6, 3.2, and 0.8 Hz, 2H), 6.40 (d, J = 17.6 Hz, 1H), 6.35

(5.77 (d, J = 11.0 Hz, 1H), 2.61 (s, 3H). 13C NMR: δ = 167.7, 157.8, 156.9, 153.1, 151.8, 151.7, 151.6, 151.1, 149.1, 147.2, 144.74,

144.69, 137.8, 137.1, 136.4, 134.3, 132.7, 131.5, 130.3, 129.8, 127.5, 126.9, 126.1, 123.7,

123.6, 122.8, 121.0, 21.5.



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UV-VIS Spectra

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

200 250 300 350 400 450 500 550

wavelength (nm)

abso

rban

ce

dMebpymVbpy

N^N

Fig. S1 UV-VIS spectra for the series of [Ir(F-mppy)2(N^N)]PF6 complexes.

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

200 250 300 350 400 450 500 550

wavelength (nm)

abso

rban

ce dMebpymVbpydVbpy

N^N

Fig. S2 UV-VIS spectra for the series of [Ir(Cl-mppy)2(N^N)]PF6 complexes.


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0

0.2

0.4

0.6

0.8

1

1.2

1.4

200 250 300 350 400 450 500 550wavelength (nm)

abso

rban

ce

dMebpymVbpy

N^N

Fig. S3 UV-VIS spectra for the series of [Ir(MeO-mppy)2(N^N)]PF6 complexes.

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

200 250 300 350 400 450 500 550

wavelength (nm)

abso

rban

ce

dMebpymVbpydVbpy

N^N

Fig. S4 UV-VIS spectra for the series of [Ir(mppy)2(N^N)]PF6 complexes.


S13

0

0.2

0.4

0.6

0.8

1

1.2

200 250 300 350 400 450 500 550

wavelength (nm)

abso

rban

ce

dMebpymVbpy

N^N

Fig. S5 UV-VIS spectra for the series of [Ir(ppy)2(N^N)]PF6 complexes.

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

200 250 300 350 400 450 500 550wavelength (nm)

abso

rban

ce

dMebpymVbpy

N^N

Fig. S6 UV-VIS spectra for the series of [Ir(Ph-ppy)2(N^N)]PF6 complexes.


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Emission Spectra

0

0.2

0.4

0.6

0.8

1

1.2

425 475 525 575 625 675 725wavelength (nm)

rela

tive

emis

sion

inte

nsity

dMebpymVbpy

N^N

Fig. S7 Relative emission intensities for the series of [Ir(F-mppy)2(N^N)]PF6 complexes

(λex = 400 nm).

0

0.2

0.4

0.6

0.8

1

1.2

425 475 525 575 625 675 725wavelength (nm)

rela

tive

emis

sion

inte

nsity

dMebpymVbpydVbpy

N^N

Fig. S8 Relative emission intensities for the series of [Ir(Cl-mppy)2(N^N)]PF6 complexes

(λex = 400 nm).


S15

0

0.2

0.4

0.6

0.8

1

1.2

425 475 525 575 625 675 725wavelength (nm)

rela

tive

emis

sion

inte

nsity

dMebpymVbpy

N^N

Fig. S9 Relative emission intensities for the series of [Ir(MeO-mppy)2(N^N)]PF6

complexes (λex = 400 nm).

0

0.2

0.4

0.6

0.8

1

1.2

425 475 525 575 625 675 725wavelength (nm)

rela

tive

emis

sion

inte

nsity

dMebpymVbpydVbpy

N^N

Fig. S10 Relative emission intensities for the series of [Ir(mppy)2(N^N)]PF6 complexes

(λex = 400 nm).


S16

0

0.2

0.4

0.6

0.8

1

1.2

425 475 525 575 625 675 725

wavelength (nm)

rela

tive

emis

sion

inte

nsity

dMebpymVbpy

N^N

Fig. S11 Relative emission intensities for the series of [Ir(ppy)2(N^N)]PF6 complexes

(λex = 400 nm).

0

0.2

0.4

0.6

0.8

1

1.2

425 475 525 575 625 675 725wavelength (nm)

rela

tive

emis

sion

inte

nsity

dMebpymVbpy

N^N

Fig. S12 Relative emission intensities for the series of [Ir(Ph-ppy)2(N^N)]PF6 complexes

(λex = 400 nm).


S17

Water Reduction Experiments

0

200

400

600

800

1000

1200

1400

0 1 2 3 4 5 6

t(h)

TON

Fig. S13 Photocatalytic hydrogen production of the photosensitizers [Ir(C^N)2(N^N)]PF6

using molecular [Rh(bpy)2Cl2]Cl as catalyst (labels, see Fig. S15).

0

50

100

150

200

250

12 12.2 12.4 12.6 12.8 13t(h)

TON


using colloidal Pt as catalyst. TONs of hydrogen production after 12h irradiation

(labels, see Fig. S15).


S18

0

20

40

60

80

100

24 24.2 24.4 24.6 24.8 25

t(h)

TON

F-mppy, dMebpy F-mppy, mVbpy Cl-mppy, dMebpy Cl-mppy, mVbpyCl-mppy, dVbpy MeO-mppy, dMebpy MeO-mppy, mVbpy mppy, dMebpymppy, mVbpy mppy, dVbpy ppy, dMebpy ppy, mVbpyPh-ppy, dMebpy Ph-ppy, mVbpy


using colloidal Pt as catalyst. TONs of hydrogen production after 24h irradiation.


S19

Table S1 Turn-over rates (TORs) of the [Ir(C^N)2(N^N)]+ photosensitizers with a colloidal Pt

catalyst after different times of irradiation.

C^N N^N TOR0.5ha TOR12h

b AF12hc TOR24h

d AF24hc

F-mppy dMebpy 595 18 0.030 5 0.008

F-mppy mVbpy 435 240 0.552 53 0.122

Cl-mppy dMebpy 1035 14 0.014 9 0.009

Cl-mppy mVbpy 520 249 0.479 51 0.098

Cl-mppy dVbpy 690 215 0.312 87 0.126

MeO-mppy dMebpy 445 11 0.025 0 0

MeO-mppy mVbpy 320 219 0.684 64 0.200

mppy dMebpy 600 12 0.020 2 0.003

mppy mVbpy 380 220 0.579 86 0.226

mppy dVbpy 455 213 0.468 93 0.204

ppy dMebpy 400 9 0.023 2 0.005

ppy mVbpy 535 161 0.301 70 0.131

Ph-ppy dMebpy 615 20 0.033 10 0.016

Ph-ppy mVbpy 740 144 0.195 5 0.007

a Average TOR at the first 30 min [TON/h]. b Turn-over rate from 12 to 13 hours irradiation

[TON/h]. c Activity factor of the photosensitizer after a certain time, determined by

comparison of the initial TOR0.5 with the current TOR (TOR/TOR0.5h) d Turn-over rate from

24 to 25 hours irradiation [TON/h].


S20

1 M. S. Lowry, W. R. Hudson, R. A. Pascal, Jr., S. Bernhard, J. Am. Chem. Soc., 2004,

126, 14129–14135.

2 C. Liu, W. Yang, Chem. Commun., 2009, 6267–6269.

3 F. Berthiol, I. Kondolff, H. Doucet, M. Santelli, J. Organomet. Chem., 2004, 689, 2786–

2798.

4 Z. Lu, T. Ladrak, O. Roubeau, J. van der Toorn, S. J. Teat, C. Massera, P. Gamez, J.

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119.

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