S. Salohiddinov, A. Vignesh, Z. Li et al.
Journal of Organometallic Chemistry 951 (2021) 122002
-119.19. FT-IR (cm−1): 3049 (w), 1658 (m), 1633 (m), 1590 (m),
1496 (s), 1487 (s), 1435 (m), 1419 (m), 1358 (m), 1273 (m), 1211
(s), 1203 (s), 1147 (m), 1090 (m), 1042 (m), 1008 (m), 925 (m), 827
(s), 792 (m), 780 (m), 745 (m), 732 (m), 720 (m). Anal. Calcd. For
C24H14 F2N2 (368.39): C, 78.25; H, 3.83; N, 7.60%. Found: C, 78.42;
H, 3.78; N, 7.64%.
counting to all above-mentioned points, we designed three dif-
ferent fluorinated ancillary Ar-BIAN ligands to obtain light emis-
sion in the lower energy region. The intention of this work was to
study on the influence of fluorine atoms in terms of photophysical
and electrochemical properties of Ir(III) complexes. Herein, we re-
ported the synthesis and characterization of three cationic iridium
complexes [(ppy)2Ir(4-FPh-BIAN)]PF6 (complex Ir1), [(ppy)2Ir(3,4-
F,FPh-BIAN)]PF6 (complex Ir2), and [(ppy)2Ir(4-CF3Ph-BIAN)]PF6
(complex Ir3) employing 2-(phenyl)pyridine (ppy) as the cyclomet-
alating ligand and corresponding (Ar-BIAN) ligands as the ancillary
ligands. The photophysical and electrochemical properties of these
complexes were investigated, and obtained results were corrobo-
rated with theoretical DFT calculations.
ꢀ
N,N -bis(3,4-difluorophenyl)acenaphthene (3,4-F,FPh-BIAN) (L2):
Obtained as a grayish-yellow solid. Yield: 1.27 g, 63 %. 1H NMR
(300 MHz, CDCl3) δ (ppm): 8.06 (d, J = 8.3 Hz, 2H), 7.56 (dd,
J = 8.3, 7.3 Hz, 2H), 7.42 – 7.30 (m, 2H), 7.15 – 6.99 (m, 4H), 6.98 –
6.88 (m, 2H). 13C NMR (100 MHz, CDCl3) δ (ppm): 162.22, 162.21,
152.32, 152.19, 149.84, 149.71, 148.99, 148.87, 147.97, 147.93, 147.89,
147.86, 146.56, 146.43, 142.09, 131.47, 129.79, 127.93, 124.12, 118.32,
118.31, 118.14, 118.13, 114.21, 114.18, 114.15, 114.12, 108.15, 107.95.
19 F NMR (470 MHz, CDCl3) δ (ppm): -135.45, -143.36. FT-IR (cm−1):
3054 (w), 1914 (w), 1670 (m), 1645 (m), 1599 (m), 1505 (w), 1489
(w), 1437 (w), 1412 (m), 1364 (w), 1321 (s), 1276 (m), 1244 (m),
1157 (m), 1125 (m), 1098 (s), 1062 (m), 1013 (m), 925 (m), 847 (m),
843 (m), 830 (m), 783 (m). Anal. Calcd. For C24H12F4N2(404.37): C,
71.29; H, 2.99; N, 6.93%. Found: C, 71.46; H, 2.82; N, 6.91%.
2. Experimental section
2.1. Materials and methods
Commercially available reagents were used as received. Reac-
tions were carried out under nitrogen atmosphere using standard
Schlenk technique. Iridium dimer [(ppy)2Ir(μ-Cl)]2 was prepared
according to literature procedure [18]. 1H and 13C NMR spectra
were recorded on Bruker Fourier 300 and Bruker Avance 400 MHz
instruments respectively, at ambient temperature using TMS as
an internal standard. 19 F NMR spectra were logged on a Bruker
Ascend 500 MHz instrument. Deuterated chloroform (CDCl3) and
deuterated dichloromethane (CD2Cl2) were used as a solvent of
record. Chemical shifts are given in parts per million (ppm) and
coupling constant (J) values in Hz. C, H and N elemental anal-
ysis were performed on Flash EA 1112 microanalyzer. Infra-Red
spectra were recorded on a Perkin Elmer System 2000 FT-IR. UV-
Visible absorption spectra were recorded at room temperature us-
ing Shimadzu UV-2600 double beam spectrophotometer. Cyclic
voltammetry (CV) analysis of complexes (Ir1-Ir3) was recorded on
electrochemical workstation CHI-660c. Sample solutions for cyclic
voltammetry were prepared in CH3CN and degassed with CH3CN-
saturated nitrogen bubbling for about 20 minutes prior to scan-
ning. Tetra(n-butyl)ammoniumhexafluorophosphate [nBu4N]PF6 0.1
M in CH3CN was used as a supporting electrolyte. [nBu4N]PF6 was
recrystallized twice with C2H5OH and dried under reduced pres-
sure prior to use. The Pt electrode, Pt wire, and Ag/AgCl elec-
trode was used working, counter, and reference electrode, respec-
tively. All the potentials were referred to the ferrocene/ferrocenium
(Fc/Fc+) taken as internal standard. All the voltametric experiments
were started and finished at a potential of 0 V and performed to-
ward clockwise direction [18].
ꢀ
N,N -bis(4-(trifluoromethyl)phenyl)acenaphthene (4-CF3Ph-BIAN)
(L3): Obtained as a yellow solid. Yield: 1.60 g, 68 %. 1H NMR (300
MHz, CDCl3) δ (ppm): 7.96 (d, J = 8.3 Hz, 1H), 7.75 (d, J = 8.3 Hz,
2H), 7.44 (dd, J = 8.3, 7.3 Hz, 1H), 7.23 (d, J = 8.2 Hz, 2H), 6.86
(d, J = 7.2 Hz, 1H). 13C NMR (100 MHz, CDCl3) δ (ppm): 161.45,
154.62, 142.21, 131.50, 129.82, 128.13, 128.07, 127.06, 127.03,
126.99, 126.95, 126.73, 125.86, 124.31, 123.16, 118.51. 19 F NMR (470
MHz, CDCl3) δ (ppm): -61.76. FT-IR (cm−1): 3054 (w), 1914 (w),
1671 (m), 1645 (m), 1599 (m), 1507 (w), 1489 (w), 1438 (w), 1412
(m), 1364 (w), 1321 (s), 1284 (m), 1276 (m), 1244 (m), 1157 (m),
1124 (m), 1097 (s), 1062 (s), 1022 (m), 1013 (m), 925 (m), 847
(m), 843 (m), 830 (s), 783 (m), 749 (m), 703 (m). Anal. Calcd. For
C26H14 F6N2 (468.40): C, 66.67; H, 3.01; N, 5.98%. Found: C, 66.37;
H, 2.97; N, 6.05%.
2.3. General procedure for the synthesis of [(C∧N)2Ir(N∧N)]PF6
complexes
The dichloro-bridged dimeric iridium complex [Ir(ppy)2 (μ-Cl)]2
(107.1 mg, 0.1 mmol) and bis(aryl)acenaphthylene-1,2-diimine (L1-
L3) (0.21 mmol) were dissolved in the mixture of dry CH2Cl2
(8 mL) and CH3OH (8 mL), then refluxed at 60°C under in-
ert (N2) atmosphere for 2 hours. Afterward, the reaction was
cooled to room temperature. Solid ammonium hexafluorophos-
phate (NH4PF6) (65.2 mg, 0.4 mmol) was added to the reaction
mixture under stirring for 1 h at ambient temperature. After evap-
oration of the solvent under reduced pressure the crude product
was dissolved in dichloromethane and then filtered off to remove
the inorganic impurities. Filtrate was recrystallized with hexane.
The desired product was obtained as green powder, which was fil-
tered and dried under reduced pressure for 36 h at 80°C. The com-
plexes were recrystallized again in CH2Cl2/n-Hex by slow evapora-
tion.
2.2. Synthesis of bis(arylimino)-acenaphthene (Ar-BIAN) ligands
(L1-L3)
All the ligands were prepared according to the Schiff’s base re-
actions of acenaphthylene-1,2-dione (0.91 g, 5 mmol) with substi-
tuted anilines (11 mmol) in the presence of catalytic amount of
p-toluene sulfonic acid in toluene. Reaction mixture was refluxed
for 6 hours at 140°C. Dean-Stark apparatus was used in order to
remove secondary product (H2O) from the reaction environment.
After completion of the reaction, the mixture was cooled to room
temperature, solvent was removed under vacuum and crude prod-
uct was recrystallized twice with ethanol.
Iridium(III)
bis[2-phenylpyridinato-N,2’]-N,N-bis(4-
fluorophenylimino)acenaphthene hexafluorophosphate (Ir1): Ob-
tained as a greenish-black solid. Yield: (184 mg, 91%). 1H NMR
(300 MHz, CD2Cl2) δ (ppm): 8.62 – 8.54 (m, 2H), 8.29 (d, J = 8.3
Hz, 2H), 7.98 – 7.89 (m, 2H), 7.81 (d, J = 8.2 Hz, 2H), 7.59 (t,
J = 7.9 Hz, 2H), 7.40 – 7.31 (m, 6H), 7.05 (s, 2H), 6.91 – 6.73 (m,
8H), 6.27 – 6.01 (m, 4H). 13C NMR (100 MHz, CD2Cl2) δ (ppm):
173.67, 167.97, 163.54, 161.07, 150.37, 148.18, 146.76, 143.43, 140.97,
139.40, 132.22, 132.18, 131.82, 130.66, 129.47, 126.91, 124.89,
124.73, 124.68, 124.36, 123.18, 122.04, 120.13, 116.87, 116.58. 19 F
NMR (470 MHz, CD2Cl2) δ (ppm): -72.46, -73.97, -112.97. FT-IR
(cm−1): 3662 (w), 3581 (w), 3049 (w), 1976 (w), 1606 (m), 1586
(m), 1559 (m), 1496 (m), 1479 (m), 1417 (m), 1360 (w), 1319 (w),
ꢀ
N,N -bis(4-fluorophenyl)acenaphthene (4-FPh-BIAN) (L1): Ob-
tained as a yellow solid. Yield: 1.41 g, 76 %. 1H NMR (300 MHz,
CDCl3) δ (ppm): 7.84 (d, J = 8.3 Hz, 2H), 7.35 (dd, J = 8.3, 7.2 Hz,
2H), 7.18 – 7.09 (m, 4H), 7.09 – 7.00 (m, 4H), 6.90 (d, J = 7.2 Hz,
2H). 13C NMR (100 MHz, CDCl3) δ (ppm): 161.90, 161.89, 161.45,
159.04, 147.67, 147.64, 141.94, 131.39, 129.33, 128.41, 127.77, 123.95,
119.87, 119.80, 116.48, 116.25. 19 F NMR (470 MHz, CDCl3) δ (ppm):
2