Inorganic Chemistry
Article
transmitted by the sample was focused onto the entrance slit of a
SpectraKinetic monochromator (Applied Photophysics). Kinetic
traces were processed by means of a Agilent digital oscilloscope. A
typical pulse energy of 2 mJ cm−2 was used.
mL of propionic acid was refluxed at 150 °C in a flask protected from
light for 1.5 h. The reaction mixture was evaporated to dryness and
purified by column chromatography on neutral alumina eluting with a
mixture of CH2Cl2/MeOH (99:1, v/v) to obtain the H2TPP-
1
[PO(OEt)2]4 as a dark purple solid. Yield: 92.4 mg (28%). H NMR
Electrochemistry. Electrochemical studies were carried out using
an IviumStat potentiostat controlled using IviumSoft. Redox
potentials were determined using cyclic voltammetry. Electro-
chemistry was performed under a nitrogen atmosphere, using a
three-electrode setup, in a single compartment cell. A platinum disc
working electrode, a Pt wire secondary electrode, and a saturated
calomel reference electrode were used. The redox potential of the
porphyrins was measured with a 1 mM analyte concentration in
anhydrous DMF that had been purged with nitrogen, with 0.1 M
LiPF6 supporting electrolyte. The redox potential of CoNMeim was
measured under the same conditions but with a 50:50 mixture of
water/acetonitrile that had been purged with nitrogen, with 0.1 M
LiClO4 supporting electrolyte. The reference electrodes were
calibrated against ferrocene.
Photocatalytic Hydrogen Evolution Experiments. For photo-
induced hydrogen evolution, each sample was prepared in a 42 mL
glass vial with a silicone septum. Prior to sample preparation, an
aqueous solution of TEOA (10 vol %) was adjusted to pH 7 using
concentrated HCl. The components were then dissolved in 10 mL of
a 1:1 (v/v) mixture of acetonitrile and aqueous TEOA (10%)
solution. The mixture was degassed for 10 min using nitrogen at room
temperature. Then, the samples were sealed and irradiated with a
white LED ring (power of 40 W, color temperature of 6400 K and
lumen of 3800 LM, Figure S17). The amounts of hydrogen evolved
were determined by gas chromatography (external standard
technique) using a Shimadzu GC 2010 plus chromatograph with a
TCD detector and a 5 Å molecular sieve column (30 m to 0.53 mm).
A total of 100 μL was taken from the headspace and injected
immediately into the GC. In all cases, the reported TON (with
respect to the porphyrin) is the average of three independent
experiments. Control experiments were performed under the same
experimental conditions. We performed various experiments by
removing only the catalyst or the photosensitizer from the hydrogen
generating system, but we did not detect any H2 production. In
addition, mercury poisoning experiments were performed, in order to
examine the possible formation of metallic nanoparticles or colloids
during the hydrogen evolution process. In these studies, an excess of
mercury (ca. 40 equiv) was added to the hydrogen evolution
solutions, but H2 production was detected at the same levels as in the
regular photocalatytic experiments (absence of mercury).
(500 MHz, CDCl3): δ 8.83 (s, 8H, pyr), 8.33 (m, 8H, o-ph), 8.22 (m,
8H, m-ph), 4.38 (m, 16H, -OCH2), 1.52 (t, J = 7.3 Hz, 24H, −CH3),
−2.83 (s, 2H, -NH) ppm. HRMS (MALDI-TOF) m/z calcd. for
C60H66N4O12P4 [M]+: 1158.3628. Found: 1158.3633. UV/vis
(CH2Cl2), λmax, nm: 419, 515, 549, 590, 646.64,65
trans-Dichloro[5,10,15,20-tetrakis(4-diethyl-phosphonate-phe-
nyl) Porphyrinato] Tin(IV) (Sn(Cl2)TPP-[PO(OEt)2]4). In a round-
bottom flask, porphyrin H2TPP-[PO(OEt)2]4 (188 mg, 0.162 mmol),
SnCl2 (307 mg, 1.62 mmol), and pyridine (30 mL) were added and
refluxed for 9 h. The solvent was evaporated to dryness under a
vacuum. The solid was dissolved in CH2Cl2 and was filtered with
Celite to obtain the Sn(Cl2)TPP-[PO(OEt)2]4 as a dark purple solid.
Yield: 108 mg (50%). Due to solubility reasons, we were unable to
record NMR spectra for Sn(Cl2)TPP-[PO(OEt)2]4. HRMS (MALDI-
TOF), m/z calcd. for C60H64Cl2N4O12P4Sn [M − Cl]+: 1311.2182.
Found: 1311.2165. UV/vis (CH2Cl2) λmax, nm: 428, 561, 600.
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge at
■
sı
Figures S1−S17 and Tables S1−S3 (PDF)
Accession Codes
CCDC 1935835 contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge
bridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
AUTHOR INFORMATION
Corresponding Authors
■
Georgios Charalambidis − University of Crete,
Elizabeth A. Gibson − Newcastle University, Newcastle
Athanassios G. Coutsolelos − University of Crete,
Synthesis. The catalysts CoPy and CoNMeim were prepared
according to the literature.17 In addition, the Zn (ZnTPyP, ZnTPP-
[COOMe]4, ZnTPP-[PO(OEt)2]4, [ZnTMePyP4+]Cl4, and nega-
tively ZnTPP-[COOH]4)36−39 and the Sn porphyrin derivatives
(Sn(OH)2TPyP, Sn(Cl2)TPP-[COOMe]4, Sn(Cl2)TPP-[PO-
(OEt)2 ]4, [Sn(OH)2 TMePyP4 +]Cl4, and Sn(Cl2 )TPP-
[COOH]4)18,40−43 were synthesized as previously reported.
Other Authors
Diethyl-4-Formylphenylphosphonate. 4-Bromobenzaldehyde
(500 mg, 2.70 mmol) was added to a 100 mL two-necked bottom
flask. To this solution, dry toluene (4 mL), dry Et3N (4 mL), and
diethylphosphite (0.4 mL, 6 mmol) were added and purged with Ar
gas for 2 min, followed by the addition of Pd(PPh3)4 (155 mg, 0.135
mmol). The reaction mixture was heated to 90 °C for 24 h under an
Ar atmosphere. The reaction mixture was cooled down to room
temperature and the solvent was evaporated to dryness under a
vacuum, redissolved in CHCl3 (35 mL), washed with distilled water
(3 × 50 mL) followed by brine solution (50 mL), and finally dried
with Na2SO4. The crude product was purified on a silica column
chromatograph using CHCl3/EtOAc (70:30, v/v) as the eluent. After
distillation under a vacuum, diethyl-4-formylphenylphosphonate was
Emmanouil Giannoudis − University of Crete,
́
Heraklion, Greece, and UMR 5249 Universite Grenoble
Alpes, CNRS, CEA, Grenoble Cedex 9, France
Elisabetta Benazzi − Newcastle University, Newcastle
upon Tyne, United Kingdom
Joshua Karlsson − Newcastle University, Newcastle upon
Tyne, United Kingdom
Graeme Copley − Newcastle University, Newcastle upon
Tyne, United Kingdom
Stylianos Panagiotakis − University of Crete, Heraklion,
Greece
Georgios Landrou − University of Crete, Heraklion,
Greece
1
obtained as a colorless liquid. Yield: 300 mg (47%). H NMR (300
MHz, CDCl3): δ 10.09 (s, 1H, CHO), 7.98(m, 4H, ph-H), 4.15(m,
4H, −CH2), 1.34(t, J = 7.1 Hz, 6H, −CH3) ppm.64
5,10,15,20-Tetrakis(4-diethyl-phosphonate-phenyl) Porphyrin
(H2TPP-[PO(OEt)2]4). A solution of diethyl-4-formylphenylphospho-
nate (280 mg, 1.18 mmol) and pyrrole (0.080 mL, 1.15 mmol) in 10
Panagiotis Angaridis − Aristotle University of
Thessaloniki, Thessaloniki, Greece
H
Inorg. Chem. XXXX, XXX, XXX−XXX
Angaridis, Panagiotis
