scholarly journals Synthesis and Characterization of White-Light Luminescent End-Capped Polyimides Based on FRET and Excited State Intramolecular Proton Transfer

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 4050
Author(s):  
Atsuko Tabuchi ◽  
Teruaki Hayakawa ◽  
Shigeki Kuwata ◽  
Ryohei Ishige ◽  
Shinji Ando

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.

RSC Advances ◽  
2016 ◽  
Vol 6 (6) ◽  
pp. 5134-5140 ◽  
Author(s):  
Chaozheng Li ◽  
Yonggang Yang ◽  
Chi Ma ◽  
Yufang Liu

The electronic density redistributes and it migrates in opposite directions for HBO when compared to those of 5A-HBO and 6A-HBO. The amino group in the HBO framework can change the behavior of the intramolecular hydrogen bonds.


2011 ◽  
Vol 3 (5) ◽  
pp. 1713-1720 ◽  
Author(s):  
Hsin-Chieh Peng ◽  
Chia-Cheng Kang ◽  
Ming-Ren Liang ◽  
Chun-Yen Chen ◽  
Alexander Demchenko ◽  
...  

2018 ◽  
Vol 96 (3) ◽  
pp. 351-357 ◽  
Author(s):  
Dapeng Yang ◽  
Min Jia ◽  
Xiaoyan Song ◽  
Qiaoli Zhang

In this work, the excited state dynamical behavior of a novel π-conjugated dye 2,2′-((5-(2-(4-methoxyphenyl)ethenyl)-benzene-1,1-diyl)-bis-(nitrilomethylylidene)-diphenol) (C1) has been investigated. Two intramolecular hydrogen bonds of C1 are tested to pre-existing in the ground state via AIM and reduced density gradient. Using a time-dependent density functional theory (TDDFT) method, it has been substantiated that the intramolecular hydrogen bonds of C1 should be strengthened in the S1 state via analyzing fundamental bond length, bond angles, and corresponding infrared vibrational modes. The most obvious variation of these two hydrogen bonds is the O4–H5···N6 bond, which might play important roles in excited state behavior for the C1 system. Furthermore, based on electronic excitation, charge transfer could occur. Just due to this kind of charge re-distribution, two hydrogen bonds should be tighter in the first excited state, which is consistent with the variation of hydrogen bond lengths. Thus, the phenomenon of charge transfer is reasonable evidence for confirming the occurrence of the excited state proton transfer (ESPT) process in the S1 state. Our theoretically constructed potential energy surfaces of C1 show that excited state single proton transfer should occur along with the O4–H5···N6 hydrogen bond rather than the O1–H2···N3 bond. We not only clarify the ESIPT mechanism for C1 but put forward new affiliation and explain a previous experiment successfully.


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