Bonding, charge transfer and aggregation of luminescent Platinum complexes at metallic interfaces
Final Report Abstract
We developed the synthesis of new Pt(II) complexes bearing tailored cyclometallated C^N*N^C luminophores, and performed their in-depth photophysical characterization. The emission of the monomeric species can be blue-shifted upon formal isosteric replacement of two C-H units by N atoms at the two cyclometallating rings. Their remarkable stability upon sublimation was demonstrated by means of scanning tunneling microscopy (STM), which also revealed a defined self-assembly behavior leading to supramolecular arrays, showing a three-fold symmetry in 2D-confined monolayers. The supramolecular organization is driven by van der Waals interactions of the side chains and does not depend on the nature of the luminophores, as also observed in the crystalline phases showing no significant Pt-Pt interactions in 3D. Conversely, the luminescence properties in glassy matrices at 77 K and in amorphous solids are indicative of intermolecular interactions with sizeable intermetallic coupling, which was demonstrated by reproducing the emission spectra of dimeric species by means of (TD)DFT calculations. The tendency towards aggregation was also traceable by cyclic voltammetry, whereas thermogravimetric analyses confirmed their stability. Solution-processed and vacuum-deposited OLED devices showed a concentration-dependent electroluminescence that red-shifts with increasing concentrations. Due to the stability of the complexes, solution-processed and vacuum-deposited devices showed identical electroluminescence spectra. Besides favoring aggregation, the introduction of two N atoms has a detrimental effect on the device performance, due to the prolonged excited state lifetimes favoring triplet-triplet annihilation.
Publications
- Phosphorescent Pt(II) complexes bearing a monoanionic CˆNˆN luminophore and tunable ancillary ligands, Dalton Trans., 46 (2017) 3160
M. Hebenbrock, L. Stegemann, J. Kösters, N. L. Doltsinis, J. Müller, C. A. Strassert
(See online at https://doi.org/10.1039/c7dt00393e) - Turn-on Fluorescence in Tetra-NHC Ligands by Rigidification via Metal Complexation: An Alternative to Aggregation-Induced Emission, Angew. Chem. Int. Ed., 56 (2017) 2785
N. Sinha, L. Stegemann, T. T. Y. Tan, N. L. Doltsinis, C. A. Strassert, F. E. Hahn
(See online at https://doi.org/10.1002/anie.201610971) - Conformation-dependent phosphorescence emission of individual mononuclear Ruthenium-(II)-bis-terpyridine complexes, Phys. Chem. Chem. Phys., 20 (2018) 24921
T. Koch, C. Höppener, N. L. Doltsinis
(See online at https://doi.org/10.1039/c8cp04580a) - Fluorination-controlled Aggregation and Intermolecular Interactions in Pt(II) Complexes with Tetradentate Luminophores, Isr. J. Chem., 58 (2018) 932
S. Wilde, D. Gonzalez-Abradelo, C. G. Daniliuc, M Böckmann, N. L. Doltsinis, C. A. Strassert
(See online at https://doi.org/10.1002/ijch.201800050) - Modification of the Potential Landscape of Molecular Rotors on Au(111) by the Presence of an STM Tip, Nano Lett., 18 (2018) 4704
H. Lu, Y. Cao, J. Qi, A. Bakker, C. A. Strassert, X. Lin, K.-H. Ernst, S. Du, H. Fuchs, H.-Y. Gao
(See online at https://doi.org/10.1021/acs.nanolett.8b01019) - Quantitative assessment of intermolecular interactions by atomic force microscopy imaging using copper oxide tips. Nat. Nanotech., 13 (2018) 371
H. Mönig, S. Amirjalayer, A. Timmer, Z.-X. Hu, L. Liu, O. Díaz Arado, M. Cnudde, C. A. Strassert, W. Ji, M. Rohlfing, H. Fuchs
(See online at https://doi.org/10.1038/s41565-018-0104-4) - Studie über den Einfluss des Fluorierungsgrades an einem tetradentaten CˆN*NˆC-Luminophor auf die photophysikalischen Eigenschaften seiner Platin(II)-Komplexe und deren Aggregation, Z. Naturforsch., 73 (2018) 849
S. Wilde, L. Stegemann, C. G. Daniliuc, T. Koch, N. L. Doltsinis, C. A. Strassert
(See online at https://doi.org/10.1515/znb-2018-0139) - Toward Tunable Electroluminescent Devices by Correlating Function and Submolecular Structure in 3D Crystals, 2D-Confined Monolayers, and Dimers, ACS Appl. Mater. Interfaces, 10 (2018) 22460
S. Wilde, D. Ma, T. Koch, A. Bakker, D. Gonzalez-Abradelo, L. Stegemann, C. G. Daniliuc, H. Fuchs, H.- Y. Gao, N. L. Doltsinis, L. Duan, C. A. Strassert
(See online at https://doi.org/10.1021/acsami.8b03528) - On-Surface Reactive Planarization of Pt(II) Complexes, Angew. Chem. Int. Ed., 58 (2019) 15396
J. Ren, M. Cnudde, D. Brünink, S. Buss, C. G. Daniliuc, L. Liu, H. Fuchs, C. A. Strassert, H.-Y. Gao, N. L. Doltsinis
(See online at https://doi.org/10.1002/anie.201906247) - Energy Transfer between CNT Surface and −Re(CO)3(phen)+* Pendants Grafted to P4VP in Nanohybrid Shish-Kebab-like Structures. J. Phys. Chem. C, 124 (2020) 1238
I. Maisuls, S. Ostendorp, G. Wilde, J. Parola, C. A. Strassert, E. Wolcan
(See online at https://doi.org/10.1021/acs.jpcc.9b10567)
