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combination with a type I photoinitiator—and as a NP precursor
under aerated conditions. To the best of our knowledge, such
a system has not been described yet. This Ag(I)-derived com-
pound appears as really promising. It likely opens the way to
the incorporation of Ag NPs in polymer matrix which could
be therefore crosslinked under air. This allows developing new
antibacterial materials for deactivating a wide range of patho-
genic microorganisms, for example. We will investigate here
the capability of the Ag-derived complex/2,2-dimethoxy-1,2-di-
phenylethan-1-one (DMPA) photoinitiating system to increase
the FRP kinetic of polymerizable acrylate matrix under air while
generating Ag NPs. Laser ash photolysis (LFP), electron spin
resonance spin-trapping (ESR-ST), and real-time Fourier trans-
form infrared spectroscopy (RT-FTIR) were used to understand
the photoreactivity of the Ag(I) complex under light activation
in a rst part. Transmission electron microscopy (TEM) experi-
ments as well as nanoindentation investigations will be used to
characterize the Ag NPs and the resulting coatings, respectively.
In a nal part, the ability of Ag-derived materials to prevent bac-
terial proliferation against two bacteria strains, Escherichia coli
(E. coli) and Staphylococcus aureus (S. aureus), will be evaluated.
2. Experimental Section
2.1. Investigated Compounds and Chemical Synthesis
Trimethylolpropane tris(3-mercaptopropionate) (Trithiol, ≥95%),
silver hexauoroantimonate (AgSbF
6
, 98%), silver chloride (AgCl,
99.99%), and triphenylphosphine (PPh
3
, 99%) were purchased
from Sigma-Aldrich. 2,2-dimethoxy-1,2-diphenylethan-1-one
(DMPA) was kindly provided by BASF company. With exception
of MeCN, which was dried with an mBraun MB-SPS-800 puri-
cation system, all reagents and chemicals in this study were used
without any further purification.
1
H,
13
C, and
31
P NMR spectra
were recorded on a JEOL 400 spectrometer. Infrared spectra
were recorded with a Nicolet Nexus FTIR spectrometer equipped
with an ATR-Germanium unit and were reported as wavenum-
bers (cm
−1
) with signal intensity expressed as weak (w), medium
(m), or strong (s). Melting points were determined using a capil-
lary tube melting point meter Krüss M5000.
2.2. Synthesis of Bis[(
µ
-Chloro)Bis(Triphenylphosphine)Silver (I)]
([Ag](PPh
3
))
[28]
A mixture of AgCl (100 mg, 0.698 mmol) and PPh
3
(366 mg,
1.396 mmol) in MeCN (3.7 mL) was stirred under reux for
18 h. After cooling to room temperature, the white solid was
removed by ltration, washed with MeCN, and dried under
vacuum to yield 1 (363 mg, 78%). White powder; mp 185 °C
(litt.
[28]
180–187 °C); IR 3054w, 1569w, 1543w, 1517w, 1479w,
1434w, 1185w, 1157w, 1094w, 1070w, 1027w, 998w, 853w,
744m, 694s cm
−1
.
31
P NMR (162 MHz, CDCl
3
)
δ
4.3 (s).
13
C{
1
H}
NMR (100 MHz, CDCl
3
)
δ
134.1 (d, J = 16.6 Hz), 133.5 (d, J =
18.3 Hz), 129.8 (s), 128.7 (d, J = 8.9 Hz).
1
H NMR (400 MHz,
CDCl
3
)
δ
7.35–7.28 (m, 9H), 7.23–7.16 (m, 6H).
13
C,
1
H and
31
P
NMR spectra of [AgCl(PPh
3
)
2
]
2
are described in Figures S1–S3
in the Supporting Information.
2.3. LFP Experiments
The nanosecond LFP setup working at 300 nm was based on
a nanosecond Nd:TAG laser (Powerlite 9010, Continuum)
operating at 5 Hz with 7–8 ns impulsion time. The analyzing
system (LP920, Edinburgh Instruments) used a 450 W pulsed
xenon arc lamp, a Czerny-Turner monochromator (spectral
width = 5 nm coupled with an emission lter LP314), a fast
photomultiplier (PMT R928 fast mode), and a transient digi-
tizer (TDS 340, Tektronix). The sample was contained in a 1 cm
cell. Measurements were done at room temperature.
2.4. ESR-ST
ESR-ST experiments were carried out using a X-Band spec-
trometer (EMX plus from Bruker Biospin) at room temperature
(293 K). The radicals were generated at room temperature using
polychromatic light irradiation (Xe–Hg lamp; Hamamatsu, LC5,
150 W) and trapped by phenyl-N-tert-butylnitrone (PBN). Irradia-
tion was carried out under air or nitrogen atmosphere. The ESR
spectra simulations were generated using the PEST WINSIM
program. All of the samples were prepared in a 6 mm quartz
cylindrical tube and dissolved in tert-butylbenzene as an inert
solvent.
2.5. Computational Details
All density functional theory (DFT) calculations were performed
with the Gaussian09 package at the B3LYP level in gas phase.
[29]
The absence of imaginary frequencies was checked on all calcu-
lated structures to confirm they were true minima. Molecular
structures, orbitals, and computed data were visualized and
analyzed with Avogadro.
[30]
Macromol. Mater. Eng. 2018, 303, 1800101
Scheme 1. Photochemical pathways involved in the photoinitiator photolysis under air.