Full Papers
doi.org/10.1002/ejic.202001077
negative eigenvalues. UV/Vis spectra and electronic transitions
LCacac emissive state is indicated, whereas the linear emissive
1
2
3
4
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were calculated using TD-DFT methods (singlet, nstates=50, CPCM,
solvent=dichloromethane) as implemented in the Gaussian16
package. Calculated geometries were visualized with GaussView.[39]
The coordinates of the optimized structures are given in the
Supporting Information.
states can be described as MLCT=LCC^ . The contributions of
C
*
the ligands to the frontier molecular orbitals were additionally
confirmed by voltammetry experiments.
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7
8
9
Electrochemistry: Cyclic voltammetry and differential pulse voltam-
metry experiments were carried out employing a Biologic SP-150
potentiostat with a glassy carbon working electrode, a platinum
wire counter electrode and an Ag/Ag+ pseudo reference electrode.
All complexes were measured as 0.5 mM solutions in degassed,
anhydrous DMF along with 0.1 M supporting electrolyte (N(n-
Bu)4ClO4) at room temperature. The CV measurements were
conducted with a sweep rate of 100 mV/s while the DP voltammo-
grams were recorded with a scan rate of 50 mV/s. All measurements
were internally referenced against ferrocene/ferrocenium (Fc/Fc+).
Experimental Section
General considerations: Compounds 3a–3c, 4a–4c and the
platinum complexes were synthesized in flame dried Schlenk tubes
under argon atmosphere, all other compounds were synthesized in
dried standard laboratory glassware under air. Solvents of at least
99.0% purity were used in all reactions in this study. Dimethyl-
formamide (DMF) was dried using standard techniques and stored
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over
molecular
sieve
and
(3 Å).
bis-1,3-(2,4,6-
Dichloro(cycloocta-1,5-diene)platinum(II)[29]
trimethyl-phenyl)propan-1,3-dione[30] were prepared according to
modified known literature procedures. The solution of trimethylsilyl
Synthesis and Characterization: A detailed description of the
synthetic procedures is given below exemplarily for each class of
compounds. The syntheses and analytical data of the analogously
prepared compounds are given in the Supporting Information.
polyphosphate (PPSE) was prepared according to
a known
literature procedure.[31] All other compounds were obtained from
1
common suppliers and were used without further purification. H-,
13C- and 195Pt-NMR spectra were acquired on Bruker NMR
Avance300, Bruker DRX 500 and Bruker Avance600 NMR spectrom-
Compound 2a: In a 250 mL round-bottom flask, a mixture of
3.568 g 2-bromoethylamine hydrobromide (98%, 17.1 mmol) and
4.777 g aniline (51.2 mmol, 3 equiv) in 64 mL toluene is refluxed for
4 h. After cooling to room temperature, the mixture is treated with
80 mL of 20% aq. NaOH until the precipitate dissolves and the
aqueous phase is extracted with dichloromethane. The combined
organic phases are washed with distilled water and dried over
magnesium sulfate. The solvent is removed in vacuo and the
product is isolated by column chromatography (dichloromethane-
1
eters. H and 13C spectra were referenced internally (1H: 7.26 ppm,
13C: 77.16 ppm for CDCl3; 1H: 2.50 ppm, 13C: 39.43 ppm for DMSO-d6;
1H: 5.32 ppm, 13C: 54.00 ppm for CD2Cl2). 195Pt spectra were
referenced externally by using potassium tetrachloroplatinate(II) in
D2O (PtCl42À : À 1617.2 ppm). Chemical shifts are given in ppm,
coupling constants J in Hz. The spectra are given in the Supporting
Information (Figures S29–S88). EI mass spectra were recorded by
GC-MS coupling on an Agilent Technologies 6890N GC system
equipped with a 5973 N mass-selective detector (70 eV). ESI mass
spectra were recorded on a Bruker Esquire LC mass spectrometer
with an ion-trap detector. Positive and negative ions were detected.
Elemental analyses were performed by the microanalytical labora-
tory of our institute on a Hekatech EA 3000 Euro Vector elemental
analyzer. Melting points were determined by using a Wagner and
1
methanol, 7:3 to 1:9) as a highly viscous liquid (1.623 g, 70%). H-
NMR (300 MHz, CDCl3): δ (ppm)=7.23–7.13 (m, 2H, CHarom), 6.71 (t,
3J=7.3 Hz, 1H, CHarom), 6.65 (d, 3J=7.7 Hz, 2H, CHarom), 4.00 (br s, 1H,
NH), 3.19 (t, 3J=5.8 Hz, 2H, NCH2CH2N), 2.96 (t, 3J=5.8 Hz, 2H,
NCH2CH2N), 1.32 (br s, 2H, NH2). 13C-NMR (75 MHz, CDCl3): δ (ppm)=
148.5 (Ci), 129.4 (CHarom), 117.6 (CHarom), 113.1 (CHarom), 46.7
(NCH2CH2N), 41.3 (NCH2CH2N). MS (EI, 70 eV) m/z (%): 136 (17) [M]+,
106 (100) [MÀ CH2NH2]+. Due to partial decomposition during work-
up no satisfying elemental analysis was received.
Munz PolyTherm
A system and are given uncorrected. The
thermogravimetric analyses were conducted with a Netzsch TG209
F1 Libra using Al2O3 crucibles under argon atmosphere (sample
chamber evacuated and refilled twice prior to analysis, 100 ml/min)
Compound 3a: 1.623 g of 2a (11.9 mmol) are dissolved in 18 mL
°
dry THF and cooled down to 0 C. Under stirring 2.033 g 4-
°
and a heat rate of 5 K/min (25–500 C).
nitrophenyl formate (98%, 11.9 mmol, 1 equiv) is added in small
portions to the solution in a time period of 15 min. After 2 h of
stirring at the same temperature the solvent is removed in vacuo,
the residue is dissolved in ethyl acetate and washed with an
aqueous saturated NaHCO3 solution. The aqueous phase is
extracted with ethyl acetate once and the combined organic phases
are dried over magnesium sulfate. The solvent is removed in vacuo
and the crude product is purified by column chromatography with
ethyl acetate as eluent affording the product as a high viscous
Photoluminescence and absorption measurements: The 2 wt%
emitter films were prepared by doctor blading a solution of an
emitter in a 10 wt% PMMA solution in dichloromethane on a quartz
substrate with a 60 mm doctor blade. After drying of the film, the
emission was measured under nitrogen atmosphere. Excitation was
conducted in a wavelength range of 280–400 nm (Xe lamp with a
monochromator), and the emission was detected with a calibrated
quantum yield detection system (Hamamatsu, model C9920-02).
The phosphorescence decay was measured with an Edinburgh
Instruments mini-t by excitation with pulses of an EPLED (360 nm,
20 kHz) and time-resolved photon counting (TCSPC). Absorption
spectra were measured on a PerkinElmer Lambda 365 UV/Vis
spectrometer in dichloromethane solutions with an analyte concen-
1
liquid (1.487 g, 76%). H-NMR (300 MHz, CDCl3): δ (ppm)=8.21 (s,
1H, OCH), 7.23–7.12 (m, 2H, CHarom), 6.79–6.68 (m, 1H, CHarom), 6.67–
6.58 (m, 2H, CHarom), 5.97 (br s, 1H, NH), 3.60–3.50 (m, 2H,
NCH2CH2N), 3.36–3.28 (m, 2H, NCH2CH2N). 13C-NMR (75 MHz, CDCl3):
δ (ppm)=161.9 (OCH), 147.9 (Ci), 129.5 (CHarom), 118.1 (CHarom), 113.0
(CHarom), 43.9 (NCH2CH2N), 37.9 (NCH2CH2N). MS (EI, 70 eV) m/z (%):
164 (12) [M]+, 106 (100) [MÀ CH2NHCHO]+. Anal. Calcd for C9H12N2O:
C 65.83, H 7.37, N 17.06, found: C 65.77, H 7.52, N 17.12.
tration of 5×10À 5 molLÀ 1
.
Computational details: The Gaussian16[32] package was used to
perform all quantum chemical calculations employing the hybrid
functionals B3LYP[33] and PBE0[34] and the local GGA functional
PBE.[35] The 6-311G*[36] basis set were used. Platinum was described
by the LANL2DZ ECP and basis set.[37] Dispersion forces were
simulated by using the D3 dispersion correction with Becke-
Johnson damping (D3BJ).[38] All given structures were verified as
true minima by vibrational frequency analysis and the absence of
Compound 4a: 1.409 g of 3a (8.6 mmol) are dissolved in 30 mL of a
dichloromethane solution of PPSE and refluxed for 2 h. After
cooling to room temperature, the mixture is extracted with distilled
water and the combined aqueous phases were made alkaline with
Na2CO3 to pH 9–10. Afterwards the aqueous phase is extracted with
dichloromethane and the combined organic phases are washed
Eur. J. Inorg. Chem. 2021, 804–813
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© 2021 The Authors. European Journal of Inorganic Chemistry published
by Wiley-VCH GmbH