Abstract
By using the density functional theory (DFT) and time-dependent density functional theory (TDDFT), the electronic structure and photophysical properties of a series of cyclometalated iridium(III) complexes bearing the substituted phenylpyrazole have been theoretically investigated. All studied iridium(III) complexes have the distorted octahedral geometry with cis-C,C, cis-O,O, and trans-N,N chelate disposition. The lowest lying singlet → singlet absorptions of all studied iridium(III) complexes are respectively located at 405 nm, 387 nm, 382 nm, 370 nm, and 387 nm. The calculated emission wavelengths for all studied iridium(III) complexes are 654 nm, 513 nm, 506 nm, 505 nm and 499 nm, respectively. The calculated emission wavelength for complex 4 at the CAM-B3LYP level is in good agreement with the experimental value. From the theoretical results, it can be seen that the electron-donating substituent groups have the important effect on the electronic structure and photophysical properties of all studied iridium(III) complexes. We hope that this study can provide valuable guidance for the design of new phosphorescent organic light-emitting diodes (OLEDs) materials.
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Ding, Y., Liu, D., Li, J. Y., Li, H. T., Ma, H. Y., Li, D. L., & Niu, R. (2020). Saturated red phosphorescent Iridium(III) complexes containing phenylquinoline ligands for efficient organic light-emitting diodes. Dyes Pigments, 179, 108405.
Hsu, L. Y., Liang, Q. M., Wang, Z. H., Kuo, H. H., Tai, W. S., Su, S. J., Zhou, X. W., Yuan, Y., & Chi, Y. (2019). Bis-tridentate Ir-III phosphors bearing two fused five-six-membered metallacycles: A strategy to improved photostability of blue emitters. Chemistry-A European Journal, 25, 15375–15386.
Dragonetti, C., Fagnani, F., Marinotto, D., di Biase, A., Roberto, D., Cocchi, M., Fantacci, S., & Colombo, A. (2020). First member of an appealing class of cyclometalated 1,3-di-(2-pyridyl)benzene platinum(ii) complexes for solution-processable OLEDs. Journal of Materials Chemistry C, 8, 7873–7881.
Cheng, G., Kwak, Y., To, W. P., Lam, T. L., Tong, G. S. M., Sit, M. K., Gong, S. L., Choi, B., Choi, W. I., Yang, C. L., & Che, C. M. (2019). High-efficiency solution-processed organic light-emitting diodes with tetradentate platinum(II) emitters. ACS Journal of Materials Chemistry C, 11, 45161–45170.
Liao, J. L., Chi, Y., Yeh, C. C., Kao, H. C., Chang, C. H., Fox, M. A., Low, P. J., & Lee, G. H. (2015). Near infrared-emitting tris-bidentate Os(II) phosphors: Control of excited state characteristics and fabrication of OLEDs. Journal of Materials Chemistry C, 3, 4910–4920.
Song, Y. L., Jiao, B. J., Liu, C. M., Peng, X. L., Wang, M. M., Yang, Y., Zhang, B., & Du, C. X. (2020). Synthesis, structures and luminescent properties of red emissive neutral copper(I) complexes with bisphosphino-substituted benzimidazole. Inorganic Chemistry Communications, 112, 107689.
Cheng, W., Wang, L. D., Zhou, Y. Y., Bian, Z. Q., Tong, B. H., Liu, Z. W., & Wang, S. (2020). Blue iridium(III) complexes with high internal quantum efficiency based on 4-(pyridin-3-yl)pyrimidine derivative and their electroluminescent properties. Dyes Pigments, 177, 108257.
Liu, J., Ma, D. G., & Bai, J. (2019). Synthesis of a new iridium complex and its yellow efficient electroluminescence with low efficiency roll-off by exhaustive optimization of device. Journal of Luminescence, 215, 116655.
Pal, A. K., Krotkus, S., Fontani, M., Mackenzie, C. F. R., Cordes, D. B., Slawin, A. M. Z., Samuel, I. D. W., & Zysman-Colman, E. (2018). High-efficiency deep-blue-emitting organic light-emitting diodes based on iridium(III) carbene complexes. Advanced Materials, 30, 1804231.
Chen, Z., Wang, L. Q., Su, S. K., Zheng, X. Y., Zhu, N. Y., Ho, C. L., Chen, S. M., & Wong, W. Y. (2017). Cyclometalated iridium(III) carbene phosphors for highly efficient blue organic light-emitting diodes. ACS Applied Materials & Interfaces, 9, 40497–40502.
Sarada, G., Sim, B., Moon, C. K., Cho, W., Kim, K. H., Sree, V. G., Park, E., Kim, J. J., & Jin, S. H. (2016). Synthesis and characterization of highly efficient blue Ir(III) complexes by tailoring beta-diketonate ancillary ligand for highly efficient PhOLED applications. Organic Electronics, 39, 91–99.
Hwang, J., Yook, K. S., Lee, J. Y., & Kim, Y. H. (2015). Synthesis and characterization of phenylpyridine derivative containing an imide functional group on an iridium(III) complex for solution-processable orange-phosphorescent organic light-emitting diodes. Dyes Pigments, 121, 73–78.
Baldo, M. A., Lamansky, S., Burrows, P. E., Thompson, M. E., & Forrest, S. R. (1999). Very high-efficiency green organic light-emitting devices based on electrophosphorescence. Applied Physics Letters, 75, 4–6.
Cleave, V., Yahioglu, G., Le Barny, P., Friend, R. H., & Tessler, N. (1999). Harvesting singlet and triplet energy in polymer LEDs. Advanced Materials, 11, 285–288.
Xie, L. M., Bai, F. Q., Li, W., Zhang, Z. X., & Zhang, H. X. (2015). Theoretical research on the effect of regulated π-conjugation on the photophysical properties of Ir(III) complexes. Physical Chemistry Chemical Physics: PCCP, 17, 10014–10021.
Wang, Y., Bai, F. Q., Ma, X. Y., & Zhang, H. X. (2018). A complete evaluation from theoretical aspect on the phosphorescent efficiency improvement through ancillary ligands modifications of a blue Ir(III) complex. Organic Electronics, 59, 293–300.
Liu, B. Q., Jabed, M. A., Guo, J. L., Xu, W., Brown, S. L., Ugrinov, A., Hobbie, E. K., Kilina, S., Qin, A. J., & Sun, W. F. (2019). Neutral Cyclometalated iridium(III) complexes bearing substituted N-heterocyclic carbene (NHC) ligands for high-performance yellow OLED application. Inorganic Chemistry, 58, 14377–14388.
Zhou, Y. H., Xu, Q. L., Han, H. B., Zhao, Y., Zheng, Y., Zhou, L., Zuo, J. L., & Zhang, H. J. (2016). Highly efficient organic light-emitting diodes with low efficiency roll-off based on iridium complexes containing pinene sterically hindered spacer. Advanced Optical Materials, 4, 1726–1731.
Zhou, Y. H., Xu, J., Wu, Z. G., & Zheng, Y. X. (2017). Synthesis, photoluminescence and electroluminescence of one iridium complex with 2-(2,4-difluorophenyl)-4-(trifluoromethyl) pyrimidine and tetraphenylimidodiphosphinate ligands. Journal of Organometallic Chemistry, 848, 226–231.
Groves, L. M., Schotten, C., Beames, J., Platts, J. A., Coles, S. J., Horton, P. N., Browne, D. L., & Pope, S. J. A. (2017). From ligand to phosphor: Rapid, machine-assisted synthesis of substituted iridium(III) pyrazolate complexes with tuneable luminescence. Chemistry—A European Journal, 23, 9407–9418.
Niu, Z. G., Han, H. B., Li, M., Zhao, Z., Chen, G. Y., Zheng, Y. X., Li, G. N., & Zuo, J. L. (2018). Tunable emission color of iridium(III) complexes with phenylpyrazole derivatives as the main ligands for organic light emitting diodes. Organometallics, 37, 3154–3164.
Wang, Y., Bao, P., Wang, J., Jia, R., Bai, F. Q., & Zhang, H. X. (2018). Comprehensive investigation into luminescent properties of Ir(III) complexes: An integrated computational study of radiative and nonradiative decay processes. Inorganic Chemistry, 57, 6561–6570.
Wang, Y., Wang, J., Zhang, H. X., Szilagyi, I. M., & Bai, F. Q. (2018). Strategies on cyclometalating ligand substitution of several Ir(III) complexes: Theoretical investigation of different molecular behaviors. Organometallics, 37, 2491–2499.
Hohenberg, P., & Kohn, W. (1964). Inhomogeneous electron gas. Physical Review, 136, B864–B871.
Adamo, C., & Barone, V. (1999). Toward reliable density functional methods without adjustable parameters: The PBE0 model. The Journal of Chemical Physics, 110, 6158–6169.
Hay, P. J., & Wadt, W. R. (1985). Ab initio effective core potentials for molecular calculations. Potentials for the transition metal atoms Sc to Hg. The Journal of Chemical Physics, 82, 270–284.
Hay, P. J., & Wadt, W. R. (1985). Ab initio effective core potentials for molecular calculations. Potentials for K to Au including the outermost core orbitals. The Journal of Chemical Physics, 82, 299–310.
Frisch, M. J., Trucks, G. W., Schlegel, H. B., Scuseria, G. E., Robb, M. A., Cheeseman, J. R., Scalmani, G., Barone, V., Mennucci, B., Petersson, G. A., Nakatsuji, H., Caricato, M., Li, X., Hratchian, H. P., Izmaylov, A. F., Bloino, J., Zheng, G., Sonnenberg, J. L., Hada, M., … Fox, D. J. (2009). Gaussian 09. Gaussian Inc.
Niehaus, T. A., Hofbeck, T., & Yersin, H. (2015). Charge-transfer excited states in phosphorescent organo-transition metal compounds: A difficult case for time dependent density functional theory? RSC Advances, 5, 63318–63329.
Cramer, C., & Truhlar, D. (1996). Solvent effects and chemical reactivity. Kluwer.
Zhao, Y., Schultz, N. E., & Truhlar, D. G. (2006). Design of density functionals by combining the method of constraint satisfaction with parametrization for thermochemistry, thermochemical kinetics, and noncovalent interactions. Journal of Chemical Theory and Computation, 2, 364–382.
Zhao, Y., & Truhlar, D. G. (2008). The M06 suite of density functionals for main group thermochemistry, thermochemical kinetics, noncovalent interactions, excited states, and transition elements: Two new functionals and systematic testing of four M06 functionals and 12 other functionals. Theoretical Chemistry Accounts, 120, 215–241.
Perdew, J. P., Burke, K., & Ernzerhof, M. (1996). Generalized gradient approximation made simple. Physical Review Letters, 77, 3865–3868.
Fantacci, S., De Angelis, F., Sgamellotti, A., Marrone, A., & Re, N. (2005). Photophysical properties of [Ru(phen)(2)(dppz)] (2+) intercalated into DNA: An integrated Car-Parrinello and TDDFT study. Journal of the American Chemical Society, 127, 14144–14145.
Tamayo, A. B., Garon, S., Sajoto, T., Djurovich, P. I., Tsyba, I. M., Bau, R., & Thompson, M. E. (2005). Cationic bis-cyclometalated iridium(III) diimine complexes and their use in efficient blue, green, and red electroluminescent devices. Inorganic Chemistry, 44, 8723–8732.
Haneder, S., Da Como, E., Feldmann, J., Lupton, J. M., Lennartz, C., Erk, P., Fuchs, E., Molt, O., Munster, I., Schildknecht, C., & Wagenblast, G. (2008). Controlling the radiative rate of deep-blue electrophosphorescent organometallic complexes by singlet-triplet gap engineering. Advanced Materials, 20, 3325–3330.
Turro, N. (1991). Modern molecular photochemistry. University Science Books.
Yang, C. H., Cheng, Y. M., Chi, Y., Hsu, C. J., Fang, F. C., Wong, K. T., Chou, P. T., Chang, C. H., Tsai, M. H., & Wu, C. C. (2007). Blue-emitting heteroleptic iridium(III) complexes suitable for high-efficiency phosphorescent OLEDs. Angewandte Chemie International Edition, 46, 2418–2421.
Avilov, I., Minoofar, P., Cornil, J., & De Cola, L. (2007). Influence of substituents on the energy and nature of the lowest excited states of heteroleptic phosphorescent Ir(III) complexes: A joint theoretical and experimental study. Journal of the American Chemical Society, 129, 8247–8258.
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The authors are grateful to the financial aid from the Program of Science and Technology Development Plan of Jilin Province of China (Grant No. 20200201099JC).
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Han, D., Ji, X., Zhao, L. et al. Theoretical insight on electronic structure and photophysical properties of a series of cyclometalated iridium(III) complexes bearing the substituted phenylpyrazole with different electron-donating or electron-accepting groups. Photochem Photobiol Sci 20, 1487–1495 (2021). https://doi.org/10.1007/s43630-021-00125-8
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DOI: https://doi.org/10.1007/s43630-021-00125-8