Photochemical & Photobiological Sciences
Page 2 of 6
DOI: 10.1039/C5PP00139K
photophysical properties of the molecule (absorption,
France) composed with
a
pulsed diode excitation source
fluorescence emission, singlet oxygen formation) have been
evaluated.
SpectraLEDꢀ415 emitting at 415 nm, cuvette compartment, a
SeyaꢀNamioka type emission monochromator (600 – 2000 nm)
60 and
a H10330ꢀ45 nearꢀinfrared photomultiplier tube with
thermoelectric cooler (HAMAMATSU) as detection system. The
system is monitored by a single photon counting controller
FluoroHubꢀB and the software DataStation and DAS6 (Horiba
JobinYvon).
2. Experimental
5
2.1 Materials and Instruments
All chemicals were obtained commercially and used as received
unless otherwise noted. Pyrrole and CH2Cl2 were redistilled
before use. All reactions were performed in the dark.
Chromatography was performed on neutral Al2O3. Reactions
65 2.2 Synthesis of 5,10,15,20-tetra(4-pyridyl)-21H,23H-
porphyrin 1
Under N2 atmosphere, pyrrole (3.48 g, 51.9 mmol) was added
10 were monitored by thinꢀlayer chromatography (TLC) using
dropwise to
a
refluxed solution (140°C) of 4ꢀ
aluminiumꢀbacked
silica
gel
plates
(Macherey–Nagel
ALUGRAM® SIL G/UV254). TLC spots were viewed under
pyridiylcarboxaldehyde (5.80 g, 54.1 mmol) dissolved in
70 propionic acid (40 mL) and the mixture is stirred under reflux for
3 hours. After removal of propionic acid in vacuo, the crude solid
was dissolved in CH2Cl2 filtered through a small pad of silica gel
and washed with CH2Cl2/EtOH (95/5, v/v). After removal of
solvent under vacuum, MeOH (500 mL) was added and the
75 resulting mixture was heated under reflux (80°C) for 1 h. The
mixture was allowed to return to room temperature and
compound 1 was crystallized by freezing and storing in a
refrigerator overnight. The crystals were filtered and washed with
cold MeOH to afford pure 1 with 10% yield (802 mg) as a light
80 purple powder; 1H NMR (300 MHz, CDCl3): δ = 9.07 (d, J = 4.3
Hz, 8H, Hoꢀpy.), 8.87 (s, 8H, Hpyrr.), 8.17 (d, J = 4.3 Hz, 8H, Hmꢀ
py.), ꢀ2.91 (s, 2H, NH) ppm; HRMS (ESI+) [C40H26N8]: calcd.
[M+H]+ 619.2358, found 619.2353.
1
ultraviolet light. H and 13C NMR spectra were recorded on a
Bruker Advance 300 spectrometer. Multiplicities are reported as
15 follow: s = singlet, d = doublet, q = quadruplet, m = multiplet, br
= broad, Ar. = aromatic. Electron spray ionization mass spectra
(ESIꢀMS) were recorded on
a Brucker MicroTofꢀQ HR
spectrometer. Absorption spectra were recorded on a Perkinꢀ
Elmer (Lambda EZ 210) double beam UVꢀVisible
20 spectrophotometer. Fluorescence spectra were recorded on a
Horiba Jobin Yvon Fluorologꢀ3 (FL3ꢀ222) spectrofluorimeter
equipped with a 450 W Xenon lamp, a thermostated cell
compartment (25°C), a R928 (HAMAMATSU Japan) UVꢀvisible
photomultiplier and a liquid nitrogen cooled InGaAs infrared
25 detector
(DSSꢀ16A020L
ElectroꢀOptical
System
Inc,
Phoenixville, PA, USA). The excitation spectrometer is a SPEX
double grating monochromator (1200 grooves/mm blazed at 330
nm). The fluorescence was measured by the UVꢀVisible detector
2.3 Synthesis of 5-(4-N-dodecylpyridyl)-10,15,20-tri(4-
85 pyridyl)-21H,23H-porphyrin monoiodide, 2
through
a
SPEX double grating monochromator (600
30 grooves/mm blazed at 500 nm). The singlet oxygen production
was measured by the IR detector through a SPEX double grating
monochromator (600 grooves/mm blazed at 1 µm). All spectra
were recorded using four optical faces quartz cells. Fluorescence
quantum yields (Φf) were determined using tetraphenyl porphyrin
35 (TPP) solution in toluene as fluorescence standard (Φf = 0.11.
Rose Bengal was chosen as reference solutions thanks to their
Under N2 atmosphere, to a solution of 1 (390 mg, 0.630 mmol)
dissolved in glacial acetic acid (16 mL) was added 1ꢀ
iodododecane (192 mg, 0.649 mmol) and the mixture was stirred
for 3 days under reflux (130°C). After removal of acid in vacuo,
90 the crude solid was dissolved in MeOH (500 mL) and the
resulting mixture was heated under reflux (80°C) for 1 h. The
mixture was allowed to return to room temperature and unreacted
1 was crystallized by freezing and storing in a refrigerator. The
compound 1 crystals were filtered off (78 mg, 80% conversion)
95 and the crude filtrate was evaporated under vacuum and purified
by neutral Al2O3 column chromatography (CH2Cl2/EtOH=96:4)
to afford 2 (174 mg, isolated yield 30%) as a light purple powder;
1H NMR (300 MHz, CDCl3): δ = 9,83 (d, J = 5.4 Hz, 2H, HoꢀNꢀ
dodecylpy.), 9.08 (d, J = 5.7 Hz, 2H, Hoꢀpy.), 9.02 (d, J = 5.4 Hz, 2H,
100 HmꢀNꢀdodecylpy.), 8.92 (s, 4H, Hpyrr.), 8.93ꢀ8.81 (m, 8H, Hpyrr. and Hoꢀ
py.), 8.15 (d, J = 5.7 Hz, 2H, Hmꢀpy.), 8.08 (d, J = 5.7 Hz, 4H, Hmꢀ
py.), 5.37ꢀ5.29 (m, 2H, αꢀCH2(dodecyl)), 2.42ꢀ2.35 (m, 2H, βꢀ
CH2(dodecyl)), 1.69ꢀ1.13 (m, 18H, CH2(dodecyl)), 0.87 (t, J = 6.6 Hz,
CH3(dodecyl)), ꢀ2.91 (s, 2H, NH) ppm; HRMS (ESI+) [C52H51N8]:
105 calcd. [M]+ 787.4236, found 787.4231.
1
high O2 quantum yields in ethanol (Φꢁ = 0.68).6 The absorbance
value at the excitation wavelength of the reference and the sample
solutions were set to around 0.2. Fluorescence lifetimes were
40 measured by TimeꢀCorrelated Single Photon Counting (TCSPC)
using for excitation: a pulsed laser diode LDHꢀPꢀCꢀ405 coupled
with a driver PDL 800ꢀD (both PicoQuant GmbH, Berlin,
Germany) emitting at 408 nm (FWHM < 70 ps, 1 MHz) and an
avalanche photodiode SPCMꢀAQRꢀ15 (EG & G, Vaudreuil
45 Canada) coupled with a 650 nm (± 10 nm) interference longꢀ
wave pass filter as detection system. The acquisition system was
a PicoHarp 300 module with a four channels router PHRꢀ800
(both PicoQuant GmbH, Berlin, Germany). Fluorescence
monoexponential decays were recorded using the single photon
50 counting method (four optical faces quartz cells for pure products
in ethanol). Data was collected up to 1000 counts accumulated in
the maximum channel and analyzed using TCSPC software
Fluofit (PicoQuant GmbH, Berlin, Germany) based on iterative
reconvolution using a LevensbergꢀMarquandt algorithm. Singlet
55 oxygen lifetime measurements have been performed on a
TEMPROꢀ01 spectrophotometer (Horiba JobinYvon – Palaiseau
2.3 Synthesis of 5-(4-N-dodecylpyridyl)-10,15,20-tri(4-N-
methylpyridyl)-21H,23H-porphyrin tetraiodide, 3
Under N2 atmosphere, to a solution of 2 (50.3 mg, 5.5 10ꢀ2 mmol)
dissolved in DMF (6 mL) was added iodomethane (456 mg, 3.23
2
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