Journal of Inorganic and General Chemistry
ARTICLE
Zeitschrift für anorganische und allgemeine Chemie
UV/Vis spectroscopic setup for KATRP/kact determination
thus was chosen to be starting point of the polymerization. Further
samples were taken in certain time intervals. The samples were
UV/Vis spectroscopic measurements were conducted with an
Avantes AvaSpec-ULS2048 CCD-Spectrometer and an Avantes Ava-
Light-DHÀ S-BAL lightsource. The measurements were performed in
Hellma QS-Screwcap-Cuvettes with an optical pathlength of
1
diluted in CDCl followed by a H-NMR spectroscopy measurement
3
to determine the conversion. Afterwards the polymer was precipi-
tated in ethanol to remove the copper complex and residual
monomer. The solid, colourless polystyrene was dried overnight at
10.00 mm.
5
0°C and molecular mass distributions were measured by GPC.
CV measurements
KATRP determination
The measurements were conducted at room temperature under
inert conditions with a Metrohm Autolab Potentiostat PGSTAT 101
using a three electrode arrangement with a Pt wire as counter
electrode, a Pt disc working electrode (1 mm diameter) and a Ag
wire as reference electrode (pseudo reference). The measurements
All measurements were conducted in oxygen free acetonitrile at
2
2°C. The acetonitrile has been degassed by three freeze-pump-
thaw cycles. Stock solutions of the complexes and the cuvettes
were prepared in a glovebox under inert conditions.
À 1
were done in CH CN/0.1 molL NBu PF6 with a sample concen-
During the measurement in the cuvette (2 mL) the concentration of
complex and initiator was 5 mM.
3
4
tration of 10 mM. Ferrocene was added afterwards as an internal
standard of the sample and all potentials are referenced relative to
+
First, stock solutions of the initiator (1.00 mmol EBrib in 10 mL of
the Fc/Fc couple. Cyclic voltammograms were measured with
I
acetonitrile) and the complexes (0.05 mmol CuBr and 0.1 mmol
200 mV/s, 100 mV/s, 50 mV/s and 20 mV/s.
ligand in 2 mL of acetonitrile) were prepared. A screw cap cuvette
containing a stirring bar was filled with 1.5 mL of acetonitrile and
tightly sealed with a silicon septum. After addition of 400 μL
catalyst solution the UV/Vis spectroscopic measurement was
started. 100 μL of EBrib solution were added and the formation of
X-ray diffraction analysis
The single crystal diffraction data for C1-I, C1-II, C2-I, C2-II, C3-I, C3-
II, C4-I, C4-II are presented in Tables S1 and S2. The data for C4-I
were collected with an Oxford KM4 XCalibur2 and for C1-I, C1-II,
C2-I, C2-II, C3-I, C3-II, C4-II on a Bruker D8 Venture with APEX CCD
detector with graphite monochromated MoÀ Kα radiation (λ=
II
the Cu species was followed via UV/Vis spectroscopy.
k
act determination
0
.71073 Å) at 100 K in a mix of ω- and φ-scans. Data reduction and
All measurements were performed in oxygen free acetonitrile at
absorption correction was performed with the programs CRYSALIS
Oxford, 2008) and CRYSALIS RED (Oxford, 2008) (C4-I) or with
2
2°C. The acetonitrile has been degassed by three freeze-pump-
(
[31]
thaw cycles. Stock solutions of the complexes and the cuvettes
were prepared in a glovebox under inert conditions.
SAINT and SADABS (C1-I, C1-II, C2-I, C2-II, C3-I, C3-II, C4-II) The
structure was solved by direct and conventional Fourier methods
and all non-hydrogen atoms were refined anisotropically with full-
During the measurement in the cuvette (2 mL) the concentration of
the complex was 3 mM. A tenfold excess of initiator and trapping
agent (30 mM) was used.
2
[32]
[33]
matrix [ least-squares based on
F
(XPREP,
SHELXS
and
34]
ShelXle ). Hydrogen atoms were derived from difference Fourier
maps and placed at idealised positions, riding on their parent C
atoms, with isotropic displacement parameters U (H)=1.2U (C)
First, stock solutions of the initiator (6.00 mmol EBrib in 10 mL of
solvent), the trapping agent (6.00 mmol TEMPO in 10 mL solvent)
and the complexes (0.05 mmol CuBr and 0.1 mmol ligand in 2 mL
of solvent) were prepared.
iso
eq
and 1.5U (C methyl). All methyl groups were allowed to rotate but
eq
not to tip.
Full crystallographic data (excluding structure factors) have been
deposited with the Cambridge Crystallographic Data Centre as
supplementary no. CCDC–2049173 for C1-I, CCDC–2049174 for C1-
II, CCDC–2049175 for C2-I, CCDC–2049176 for C2-II, CCDC–2049177
for C3-I, CCDC–2049178 for C3-II, CCDC–2049179 for C4-I and
CCDC–2049180 C4-II. Copies of the data can be obtained free of
charge on application to CCDC, 12 Union Road, Cambridge CB2
A screw cap cuvette containing a stirring bar was filled with
1
.26 mL acetonitrile and tightly sealed with a silicon septum. After
addition of 100 μL initiator and 400 μL TEMPO solution the UV/Vis
spectroscopic measurement was started. By adding 240 μL of
complex solution the reaction was initiated and the formation of
II
the Cu species was followed via UV/Vis spectroscopy.
1EZ, UK (fax: (+44)1223-336-033; e-mail: deposit@ccdc.cam.ac.uk).
Acknowledgements
Polymerization procedure
Styrene (Acros Organics, 99% stab.) and the initiator ethyl α-
bromoisobutyrate (EBrib, abcr, 98%) have been purified by
J.S.M. thanks the Konrad-Adenauer-Stiftung for generous
financial support in form of a fellowship. Open access funding
enabled and organized by Projekt DEAL.
distillation over CaH . All polymerizations were conducted with
2
in situ generated catalysts. First CuBr (0.23 mmol, 1 eq.), then ligand
(0.46 mmol, 2 eq.) were directly weighed into the polymerization
vessel under nitrogen atmosphere inside a glovebox. Outside the
glove box styrene (23 mmol, 100 eq.), benzonitrile (1.13 mL) and
finally the initiator EBrib (0.23 mmol, 1 eq.) were added with
gastight glass syringes using Schlenk technique.
Keywords: Copper · Atom transfer radical polymerization ·
Kinetics · Guanidines · Ligand design
After addition of the initiator, the solution was heated to 110°C
under vigorous stirring. The first aliquot was taken with a glass
pipette under inert conditions after 2.5 min. At this point of time
the polymerization mixture reached its desired temperature and
[
Z. Anorg. Allg. Chem. 2021, 832–842
840 © 2021 The Authors. Zeitschrift für anorganische und allgemeine Chemie
published by Wiley-VCH GmbH.
Kr?ckert, Konstantin W.
