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Liu H, Isoda R, Doi M, Muto K, Ando S. Pressure-Induced Enhancement of Room-Temperature Phosphorescence in Heavy Halogen-Containing Imide and Polyimide. J Phys Chem B 2024. [PMID: 39054756 DOI: 10.1021/acs.jpcb.4c03946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2024]
Abstract
To investigate the correlation between the aggregated state and photoluminescence (PL) mechanism of dual fluorescent (FL) and phosphorescent (PH) polyimides (PIs), the photophysical processes of FL-type BP-PI, PH-type DBrBP-PI, and their corresponding imide model compounds (BP-MC and DBrBP-MC) dispersed in poly(methyl methacrylate) (PMMA) films were analyzed at elevated pressures up to 8 GPa using a diamond anvil cell. Dibromo-substituted DBrBP-MC demonstrated a shorter wavelength absorption than BP-MC owing to the larger dihedral angle in the biphenyl moiety. Both MCs exhibited red-shifts in their absorption spectra with increasing pressure, indicating planarization occurred at the biphenyl moieties associated with the compression of the free volume in PMMA. The PL intensity of BP-MC increased with increasing pressure, while its quantum yield (ΦPL) decreased sharply due to the enhanced energy transfer via the Förster mechanism. In contrast, the PH quantum yield (ΦPH) of DBrBP-MC monotonically increased at lower pressures, while it showed excitation wavelength-dependent behaviors at higher pressures: ΦPH remained unchanged under excitation at 340 nm but gradually increased under excitation at 365 nm. This fact suggests that, at higher pressures, 365 nm excitation promoted intersystem crossing (ISC) from excited singlet states at higher energy levels. Using this phenomenon, a significant pressure-induced PH enhancement (PIPE) was observed for DBrBP-PI up to 0.9 GPa upon excitation at 365 nm, which is a rare phenomenon for organic polymers. This study indicates that even in colorless and optically transparent amorphous polymers, an enhancement of PH due to restricted molecular motion and intensified ISC outweighs the deactivation due to intermolecular energy transfer under certain pressures, leading to an increase in ΦPH.
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Affiliation(s)
- Haonan Liu
- Department of Chemical Science and Engineering, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8552, Japan
| | - Ryuichi Isoda
- Department of Chemical Science and Engineering, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8552, Japan
| | - Marina Doi
- Department of Chemical Science and Engineering, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8552, Japan
| | - Koichiro Muto
- Department of Chemical Science and Engineering, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8552, Japan
| | - Shinji Ando
- Department of Chemical Science and Engineering, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8552, Japan
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Nara M, Fujiwara E, Vyšniauskas A, Gulbinas V, Ando S. Photophysical analysis of dual fluorescence and phosphorescence emissions observed for semi-aliphatic polyimides at lower temperatures. Phys Chem Chem Phys 2024; 26:15461-15471. [PMID: 38748239 DOI: 10.1039/d4cp00538d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
The photoluminescence (PL) properties of four types of blue fluorescent semi-aliphatic polyimides (PIs) derived from aromatic dianhydrides (ODPA, BPDA, HQDEA, and BPADA) and an alicyclic diamine (DCHM) were investigated at temperatures ranging from room temperature (RT, 298 K) to 30 K to analyse the origins of their non-radiative relaxation (NR) processes. These PIs exhibited significant increases in fluorescence (FL) intensity and lifetimes when lowering the temperature, stabilising below 100 K. The PIs containing ether (-O-) linkages showed a shoulder peak at around 500 nm below 150 K, which is attributable to phosphorescence (PH). These results show that the NR deactivation at RT includes three processes: intersystem crossing (ISC) from the excited singlet (S1) to the triplet (T1) state, temperature-dependent NR from the S1 state, which becomes suppressed below around 100 K, and temperature-independent NR. Based on the analyses of the temperature dependences, polymer structures, and quantum chemical analysis of molecular orbitals, we contemplate that the temperature-dependent NR is attributable to the excitation quenching by defect states mediated by excitation migration, and the temperature-independent NR may be caused by the deactivation of the excited state induced by molecular vibrations.
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Affiliation(s)
- Mayuko Nara
- Department of Chemical Science and Engineering, Tokyo Institute of Technology, Ookayama 2-12-1-E4-5, Meguro-ku, Tokyo 152-8552, Japan.
| | - Eisuke Fujiwara
- Department of Chemical Science and Engineering, Tokyo Institute of Technology, Ookayama 2-12-1-E4-5, Meguro-ku, Tokyo 152-8552, Japan.
| | - Aurimas Vyšniauskas
- Centre for Physical Sciences and Technology, Sauletekio av. 3, Vilnius 10257, Lithuania.
| | - Vidmantas Gulbinas
- Centre for Physical Sciences and Technology, Sauletekio av. 3, Vilnius 10257, Lithuania.
| | - Shinji Ando
- Department of Chemical Science and Engineering, Tokyo Institute of Technology, Ookayama 2-12-1-E4-5, Meguro-ku, Tokyo 152-8552, Japan.
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Ando S. Characteristic changes in the structures and properties of polyimides induced by very high pressures up to 8 GPa. Polym J 2023. [DOI: 10.1038/s41428-023-00759-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
AbstractVarious in situ measurement techniques have been applied to investigate changes in the three-dimensional structures and the properties of fully aromatic polymers (mainly aromatic polyimides: PIs) generated at very high pressures up to 8 GPa. In particular, significant changes occurred in the ordered structures, aggregation states, electronic structures, and intermolecular interactions in the repeating units of the PI molecular chains and were observed by applying pressure with a high-pressure optical cell (up to 0.4 GPa, ca. 4000 atm) or a diamond anvil cell (DAC, up to 8.0 GPa, ca. 80,000 atm). In addition, the structural changes in the PI molecular chain repeating units and interchain distances induced by the ultrahigh pressures were observed with wide-angle X-ray diffraction, and they were compared and contrasted with optical absorption, fluorescent and phosphorescent emission spectra, infrared absorption spectra, and refractive indexes observed under the same conditions. These findings obtained at very high pressures provide molecular design guidelines for new PI materials with novel optical, electronic, and thermal functionalities that are not easy to achieve under ambient conditions.
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Hwang SH, Kim H, Ryu H, Serdiuk IE, Lee D, Choi TL. Powerful Direct C-H Amidation Polymerization Affords Single-Fluorophore-Based White-Light-Emitting Polysulfonamides by Fine-Tuning Hydrogen Bonds. J Am Chem Soc 2021; 144:1778-1785. [PMID: 34968031 DOI: 10.1021/jacs.1c11100] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The development of white-light-emitting polymers has been actively pursued because of the importance of such polymers in various applications, such as lighting sources and displays. To generate white-light, numerous research efforts have focused on synthesizing multifluorophore-based random copolymers to effectively cover the entire visible region. However, due to their intrinsic synthetic and structural features, this strategy has limitations in securing color reproducibility and stability. Herein, we report the development of single-fluorophore-based white-light-emitting homopolymers with excellent color reproducibility. A powerful direct C-H amidation polymerization (DCAP) strategy enabled the synthesis of defect-free polysulfonamides that emit white-light via excited-state intramolecular proton-transfer (ESIPT). To gain structural insights for designing such polymers, we conducted detailed model studies by varying the electronic nature of substituents that allow facile tuning of the emission colors. Further analysis revealed precise control of the thermodynamics of the ESIPT process by fine-tuning the strength of the intramolecular hydrogen bond. By applying this design principle to polymerization, we successfully produced a series of well-defined polysulfonamides with single-fluorophore emitting white-light. The resulting polymers emitted consistent fluorescence, regardless of their molecular weights or phases (i.e., solution, powder, or thin film), guaranteeing excellent color reproducibility. With these advantages in hand, we also demonstrated practical use of our DCAP system by fabricating a white-light-emitting coated LED.
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Affiliation(s)
- Soon-Hyeok Hwang
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
| | - Hongsik Kim
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
| | - Hanseul Ryu
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
| | - Illia E Serdiuk
- Faculty of Mathematics, Physics and Informatics, University of Gdańsk, Wita Stwosza 57, 80-308 Gdańsk, Poland
| | - Dongwhan Lee
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
| | - Tae-Lim Choi
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
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Synthesis and Characterization of White-Light Luminescent End-Capped Polyimides Based on FRET and Excited State Intramolecular Proton Transfer. Polymers (Basel) 2021; 13:polym13224050. [PMID: 34833349 PMCID: PMC8621099 DOI: 10.3390/polym13224050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 11/18/2021] [Accepted: 11/19/2021] [Indexed: 11/17/2022] Open
Abstract
N-cyclohexylphthalimide-substituted trifluoroacetylamino (CF3CONH-) group (3TfAPI), which forms an intramolecular hydrogen bond, was synthesized, and it exhibited a bright yellow fluorescence owing to the excited-state intramolecular proton transfer (ESIPT) in the solution and crystalline states. In addition, CF3CONH-substituted phthalic anhydride (3TfAPA) was synthesized, which was attached to the termini of a blue-fluorescent semi-aromatic polyimide (PI) chain. Owing to the efficient Förster resonance energy transfer (FRET) occurring from the main chain to the termini and the suppression of deprotonation (anion formation) at the 3TfAPA moiety by H2SO4 doping, the resulting PI films display bright white fluorescence. Moreover, the enhancement of the chain rigidity by substituting the diamine moiety results in an increase in the quantum yield of white fluorescence (Φ) by a factor of 1.7, due to the suppression of local molecular motion. This material design strategy is promising for preparing thermally stable white-light fluorescent PIs applicable to solar spectral convertors, displays, and ICT devices.
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Li J, Feng S, Feng X, Wu J, Xu L. The excited state behaviors of 3-(benzo[d]thiazol-2-yl)-2-hydroxy-5-methoxybenzaldehyde system in aprotic solvents. Chem Phys 2021. [DOI: 10.1016/j.chemphys.2021.111280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Doi M, Muto K, Nara M, Liang N, Sano K, Mori H, Ishige R, Ando S. Photoluminescence Properties of Copolyimides Containing Naphthalene Core and Analysis of Excitation Energy Transfer between the Dianhydride Moieties. J PHOTOPOLYM SCI TEC 2021. [DOI: 10.2494/photopolymer.34.423] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Marina Doi
- Department of Chemical Science and Engineering, Tokyo Institute of Technology
| | - Koichiro Muto
- Department of Chemical Science and Engineering, Tokyo Institute of Technology
| | - Mayuko Nara
- Department of Chemical Science and Engineering, Tokyo Institute of Technology
| | - Naiqiang Liang
- Department of Chemical Science and Engineering, Tokyo Institute of Technology
| | - Kosuke Sano
- Chemical Research Laboratory, JFE Chemical Corporation
| | - Hiroaki Mori
- Chemical Research Laboratory, JFE Chemical Corporation
| | - Ryohei Ishige
- Department of Chemical Science and Engineering, Tokyo Institute of Technology
| | - Shinji Ando
- Department of Chemical Science and Engineering, Tokyo Institute of Technology
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