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Maity M, Bala I, Kanakala MB, Gupta SP, Yelamaggad CV, Pal SK. Tailoring Chiral Discotic Liquid Crystals: Mesophase Engineering through Alternative Approaches and Chain Lengths. Chem Asian J 2024; 19:e202300936. [PMID: 37988364 DOI: 10.1002/asia.202300936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 11/16/2023] [Accepted: 11/16/2023] [Indexed: 11/23/2023]
Abstract
Hydrogen (H)-bonding is crucial in constructing superstructures in chemical (such as chiral discotic liquid crystals (DLCs)) as well as in biological systems due to its specific and directional nature. In this context, we achieved the successful synthesis of two branches of heptazine-based H-bonded complexes using distinct strategies. Hpz*-Es-Cn , we incorporated chiral alkyl tails (Hpz-chiral) onto the central C3 symmetric heptazine core, connected to achiral benzoic acid derivatives (Es-Cn acid) through H-bonding. In Hpz-Es-Cn -acid*, we used an achiral heptazine derivative (Hpz-Es-Cn ) linked to a chiral acid via H-bonding. On the other hand, based on the DSC results, we observed that Hpz*-Es-Cn complexes exhibited three distinct phases, whereas Hpz-Es-Cn -acid* complexes displayed only a single mesophase. In polarized optical microscopy (POM) observations, all the complexes displayed birefringence at room temperature, with the color of the POM images changing as the temperature varied. X-ray diffraction (XRD) studies at lower temperatures confirmed that Hpz*-Es-C8 exhibited the columnar rectangular (Colr ) phase, while Hpz*-Es-C10/12 exhibited the columnar oblique (Colob ) phase. However, all the H-bonded complexes exhibited the columnar hexagonal (Colh ) phase at higher temperatures. The chiroptical spectra recorded by Circular dichroism (CD) highlight the specific observations in the columnar phase of two complexes, Hpz*-Es-C10 and Hpz*-Es-C12 . This behavior has potential applications in various fields, including sensors, displays, and responsive materials.
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Affiliation(s)
- Madhusudan Maity
- Department of Chemical Science, Indian Institute of Science Education and Research (IISER) Mohali, Punjab, 140306, India
- Knowledge City, Sector 81, SAS Nagar, Manauli, PO 140306, India
| | - Indu Bala
- Department of Chemical Science, Indian Institute of Science Education and Research (IISER) Mohali, Punjab, 140306, India
- Knowledge City, Sector 81, SAS Nagar, Manauli, PO 140306, India
| | | | | | - C V Yelamaggad
- Centre for Nano and Soft Matter Sciences, Bengaluru, 560013, India
| | - Santanu Kumar Pal
- Department of Chemical Science, Indian Institute of Science Education and Research (IISER) Mohali, Punjab, 140306, India
- Knowledge City, Sector 81, SAS Nagar, Manauli, PO 140306, India
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2
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Sun W, Wang C, Tian C, Li X, Hu X, Liu S. Nanotechnology for brain tumor imaging and therapy based on π-conjugated materials: state-of-the-art advances and prospects. Front Chem 2023; 11:1301496. [PMID: 38025074 PMCID: PMC10663370 DOI: 10.3389/fchem.2023.1301496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 10/26/2023] [Indexed: 12/01/2023] Open
Abstract
In contemporary biomedical research, the development of nanotechnology has brought forth numerous possibilities for brain tumor imaging and therapy. Among these, π-conjugated materials have garnered significant attention as a special class of nanomaterials in brain tumor-related studies. With their excellent optical and electronic properties, π-conjugated materials can be tailored in structure and nature to facilitate applications in multimodal imaging, nano-drug delivery, photothermal therapy, and other related fields. This review focuses on presenting the cutting-edge advances and application prospects of π-conjugated materials in brain tumor imaging and therapeutic nanotechnology.
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Affiliation(s)
- Wenshe Sun
- Department of Interventional Medical Center, Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
- Qingdao Cancer Institute, Qingdao University, Qingdao, China
| | - Congxiao Wang
- Department of Interventional Medical Center, Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Chuan Tian
- Department of Interventional Medical Center, Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Xueda Li
- Department of Interventional Medical Center, Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Xiaokun Hu
- Department of Interventional Medical Center, Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Shifeng Liu
- Department of Interventional Medical Center, Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
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3
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Yang W, Luo D, Li G, Luo Q, Banwell MG, Chen L. Synthesis of Pyridin-1(2 H)-ylacrylates and the Effects of Different Functional Groups on Their Fluorescence. Molecules 2023; 28:6511. [PMID: 37764287 PMCID: PMC10536652 DOI: 10.3390/molecules28186511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 08/25/2023] [Accepted: 09/01/2023] [Indexed: 09/29/2023] Open
Abstract
While fluorescent organic materials have many potential as well as proven applications and so have attracted significant attention, pyridine-olefin conjugates remain a less studied subset of such systems. Herein, therefore, we report on the development of the straightforward syntheses of pyridin-1(2H)-ylacrylates and the outcomes of a study of the effects of substituents on their fluorescent properties. Such compounds were prepared using a simple, metal-free and three-component coupling reaction involving 2-aminopyridines, sulfonyl azides and propiolates. The fluorescent properties of the ensuing products are significantly affected by the positions of substituents on the cyclic framework, with those located in central positions having the greatest impact. Electron-withdrawing groups tend to induce blue shifts while electron-donating ones cause red shifts. This work highlights the capacity that the micro-modification of fluorescent materials provides for fine-tuning their properties such that they may be usefully applied to, for example, the study of luminescent materials.
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Affiliation(s)
- Weiguang Yang
- Key Laboratory of Big Data Mining and Precision Drug Design of Guangdong Medical University, The Marine Biomedical Research Institute, Guangdong Medical University, Zhanjiang 524023, China; (D.L.); (G.L.)
| | - Danyang Luo
- Key Laboratory of Big Data Mining and Precision Drug Design of Guangdong Medical University, The Marine Biomedical Research Institute, Guangdong Medical University, Zhanjiang 524023, China; (D.L.); (G.L.)
| | - Guanrong Li
- Key Laboratory of Big Data Mining and Precision Drug Design of Guangdong Medical University, The Marine Biomedical Research Institute, Guangdong Medical University, Zhanjiang 524023, China; (D.L.); (G.L.)
| | - Qiaoli Luo
- School of Chemistry and Chemical Engineering, Lingnan Normal University, Zhanjiang 524048, China;
| | - Martin G. Banwell
- Key Laboratory of Big Data Mining and Precision Drug Design of Guangdong Medical University, The Marine Biomedical Research Institute, Guangdong Medical University, Zhanjiang 524023, China; (D.L.); (G.L.)
- Institute for Advanced and Applied Chemical Synthesis (IAACS), Jinan University, Guangzhou 510632, China
| | - Lanmei Chen
- Key Laboratory of Big Data Mining and Precision Drug Design of Guangdong Medical University, The Marine Biomedical Research Institute, Guangdong Medical University, Zhanjiang 524023, China; (D.L.); (G.L.)
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4
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Tang H, Chen Q, Meng G, Lu S, Qin J, Yang K, Gao L, Wang Z, He Y. A graphitic-C 3N 4 derivative containing heptazines merged with phenyls: synthesis, purification and application as a high-efficiency metal-free quasi-green phosphor for white LEDs. RSC Adv 2023; 13:12509-12517. [PMID: 37091623 PMCID: PMC10120611 DOI: 10.1039/d3ra00473b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Accepted: 03/31/2023] [Indexed: 04/25/2023] Open
Abstract
Because rare-earth elements are scarce, expensive, and unsustainable, it is of great significance to develop rare-earth-free (even metal-free) luminescent materials as phosphors for LEDs. Here, a graphitic-C3N4 (g-C3N4) derivative containing some heptazines merged with phenyls has been synthesized via thermal polymerization of melamine and quinazoline-2,4(1H,3H)-dione at an optimal mole ratio of 18 : 1. In comparison with g-C3N4 synthesized from melamine only, the photoluminescent (PL) emission colour changed from blue to green, the maximum emission wavelength (λ em,max) changed from 467 nm to 508 nm, and the PL quantum yield (PLQY) increased from 8.0% to 24.0%. It was further purified via vacuum sublimation, and a product with yellowish green emission (λ em,max = 517 nm) and PLQY up to 45.5% was obtained. This sublimated product had high thermal stability and low thermal quenching; its thermal decomposition temperature was as high as 527 °C, and its relative PL emission intensity at 100 °C was 90.8% of that at 20 °C. Excited by blue light chips (λ em,max ≈ 460 nm), cold, neutral and warm white LEDs can be fabricated using the sublimated product and orange-emitting (Sr,Ba)3SiO5:Eu2+ as phosphors. The good performances of these white LEDs (for example, the CIE coordinates, color rendering index and correlated color temperature were (0.31, 0.33), 84.4 and 6577 K, respectively) suggest that the low-efficiency blue-emitting g-C3N4 had been successfully converted into a high-efficiency metal-free quasi-green phosphor.
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Affiliation(s)
- Huaijun Tang
- Key Laboratory of Green-Chemistry Materials in University of Yunnan Province, National and Local Joint Engineering Research Center for Green Preparation Technology of Biobased Materials, School of Chemistry & Environment, Yunnan Minzu University Kunming 650500 P. R. China
| | - Qiuhong Chen
- Key Laboratory of Green-Chemistry Materials in University of Yunnan Province, National and Local Joint Engineering Research Center for Green Preparation Technology of Biobased Materials, School of Chemistry & Environment, Yunnan Minzu University Kunming 650500 P. R. China
| | - Guoyun Meng
- Department of Chemistry, Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Tsinghua University Beijing 100084 P. R. China
| | - Shiyou Lu
- Key Laboratory of Green-Chemistry Materials in University of Yunnan Province, National and Local Joint Engineering Research Center for Green Preparation Technology of Biobased Materials, School of Chemistry & Environment, Yunnan Minzu University Kunming 650500 P. R. China
| | - Jing Qin
- Key Laboratory of Green-Chemistry Materials in University of Yunnan Province, National and Local Joint Engineering Research Center for Green Preparation Technology of Biobased Materials, School of Chemistry & Environment, Yunnan Minzu University Kunming 650500 P. R. China
| | - Kaixin Yang
- Key Laboratory of Green-Chemistry Materials in University of Yunnan Province, National and Local Joint Engineering Research Center for Green Preparation Technology of Biobased Materials, School of Chemistry & Environment, Yunnan Minzu University Kunming 650500 P. R. China
| | - Long Gao
- Key Laboratory of Green-Chemistry Materials in University of Yunnan Province, National and Local Joint Engineering Research Center for Green Preparation Technology of Biobased Materials, School of Chemistry & Environment, Yunnan Minzu University Kunming 650500 P. R. China
| | - Zhengliang Wang
- Key Laboratory of Green-Chemistry Materials in University of Yunnan Province, National and Local Joint Engineering Research Center for Green Preparation Technology of Biobased Materials, School of Chemistry & Environment, Yunnan Minzu University Kunming 650500 P. R. China
| | - Yonghui He
- Key Laboratory of Chemistry in Ethnic Medicinal Resources, State Ethnic Affairs Commission & Ministry of Education, Yunnan Minzu University Kunming 650500 China
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Zhao Y, Wang C, Han X, Lang Z, Zhao C, Yin L, Sun H, Yan L, Ren H, Tan H. Two-Dimensional Covalent Heptazine-Based Framework Enables Highly Photocatalytic Performance for Overall Water Splitting. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2202417. [PMID: 35948503 PMCID: PMC9534949 DOI: 10.1002/advs.202202417] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 07/03/2022] [Indexed: 06/15/2023]
Abstract
Screening high-efficiency 2D conjugated polymers toward visible-light-driven overall water splitting (OWS) is one of the most promising but challenging research directions to realize solar-to-hydrogen (STH) energy conversion and storage. "Mystery molecule" heptazine is an intriguing hydrogen evolution reaction (HER) building block. By covalently linking with the electron-rich alkynyl and phenyl oxygen evolution reaction (OER) active units, 10 experimentally feasible 2D covalent heptazine-based frameworks (CHFs) are constructed and screened four promising visible-light-driven OWS photocatalysts, which are linked by p-phenyl (CHF-4), p-phenylenediynyl (CHF-7), m-phenylenediynyl (CHF-8), and phenyltriynyl (CHF-9), respectively. Their HER and OER active sites achieve completely spatially separated, where HER active sites focus on heptazine units and OER active sites located on alkynyl or phenyl units. Their lower overpotentials allow them to spontaneously trigger the surface OWS reaction under their own light-induced bias without using any sacrificial agents and cocatalysts. Among them, CHF-7 shows the best photocatalytic performance with an ideal STH energy conversion efficiency estimated at 12.04%, indicating that it is a promising photocatalyst for industrial OWS. This work not only provides an innovative idea for the exploration of novel polymer photocatalysts for OWS but also supplies a direction for the development of heptazine derivatives.
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Affiliation(s)
- Yingnan Zhao
- Key Laboratory of Polyoxometalate and Reticular Material Chemistry of Ministry of EducationFaculty of ChemistryNortheast Normal UniversityChangchun130024P. R. China
| | - Cong Wang
- School of Materials Science and EngineeringChangchun University of Science and TechnologyChangchun130022P. R. China
| | - Xingqi Han
- Key Laboratory of Polyoxometalate and Reticular Material Chemistry of Ministry of EducationFaculty of ChemistryNortheast Normal UniversityChangchun130024P. R. China
| | - Zhongling Lang
- Centre for Advanced Optoelectronic Functional Materials ResearchKey Laboratory of UV‐Emitting Materials and TechnologyMinistry of EducationNortheast Normal UniversityChangchun130024P. R. China
| | - Congcong Zhao
- Key Laboratory of Polyoxometalate and Reticular Material Chemistry of Ministry of EducationFaculty of ChemistryNortheast Normal UniversityChangchun130024P. R. China
| | - Liying Yin
- Key Laboratory of Polyoxometalate and Reticular Material Chemistry of Ministry of EducationFaculty of ChemistryNortheast Normal UniversityChangchun130024P. R. China
| | - Huiying Sun
- Key Laboratory of Polyoxometalate and Reticular Material Chemistry of Ministry of EducationFaculty of ChemistryNortheast Normal UniversityChangchun130024P. R. China
| | - Likai Yan
- Key Laboratory of Polyoxometalate and Reticular Material Chemistry of Ministry of EducationFaculty of ChemistryNortheast Normal UniversityChangchun130024P. R. China
| | - Hongda Ren
- Key Laboratory of Polyoxometalate and Reticular Material Chemistry of Ministry of EducationFaculty of ChemistryNortheast Normal UniversityChangchun130024P. R. China
| | - Huaqiao Tan
- Key Laboratory of Polyoxometalate and Reticular Material Chemistry of Ministry of EducationFaculty of ChemistryNortheast Normal UniversityChangchun130024P. R. China
- State Key Laboratory for Chemistry and Molecular Engineering of Medicinal ResourcesMinistry of Science and Technology of ChinaSchool of Chemistry and Pharmaceutical SciencesGuangxi Normal UniversityGuilin541004China
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6
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Kiuchi H, Sonoda Y, Miyake Y, Kobayashi F, Tsutsumi J, Tadokoro M, Kanai K. Mechanism of high photoluminescence quantum yield of melem. Phys Chem Chem Phys 2022; 24:23602-23611. [PMID: 36134431 DOI: 10.1039/d2cp03693b] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
To produce high-efficiency organic light-emitting diodes, materials that exhibit thermally activated delayed fluorescence (TADF) are attracting attention as alternatives to phosphorescent materials containing heavy metallic elements. Melem, a small molecule with a heptazine backbone composed only of nitrogen, carbon, and hydrogen, is known to emit light in the near-ultraviolet region and exhibit high photoluminescence (PL) quantum yield and delayed fluorescence. However, the mechanism underlying the high PL quantum yield remains unclear. This study aimed to elucidate the mechanism of the high PL quantum yield of melem by examining its optical properties in detail. When the amount of dissolved oxygen in the melem solution was increased by bubbling oxygen through it, the PL quantum yield and emission lifetime decreased significantly, indicating that the triplet state was involved in the light-emission mechanism. Furthermore, the temperature dependence of the PL intensity of melem was investigated; the PL intensity decreased with decreasing temperature, indicating that it increases thermally. The experimental results show that melem is a TADF material that produces an extremely high PL quantum yield by upconversion from the triplet to the singlet excited state.
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Affiliation(s)
- Hiroki Kiuchi
- Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
| | - Yoriko Sonoda
- Research Institute for Advanced Electronics and Photonics, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, 305-8565 Tsukuba, Ibaraki, Japan
| | - Yuto Miyake
- Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
| | - Fumiya Kobayashi
- Department of Chemistry, Faculty of Science, Tokyo University of Science, Kagurazaka 1-3, Shinjuku-ku, Tokyo 162-8601, Japan
| | - Jun'ya Tsutsumi
- Research Institute for Advanced Electronics and Photonics, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, 305-8565 Tsukuba, Ibaraki, Japan
| | - Makoto Tadokoro
- Department of Chemistry, Faculty of Science, Tokyo University of Science, Kagurazaka 1-3, Shinjuku-ku, Tokyo 162-8601, Japan
| | - Kaname Kanai
- Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
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Zhong H, Li L, Zhu S, Wang Y. Controllable self-assembly of thiophene-based π-conjugated molecule and further construction of pillar[5]arene-based host-guest white-light emission system. Front Chem 2022; 10:980173. [PMID: 36118325 PMCID: PMC9478560 DOI: 10.3389/fchem.2022.980173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 08/09/2022] [Indexed: 11/13/2022] Open
Abstract
Photoluminescence materials have been widely applied in biological imaging and sensing, anti-counterfeiting, light-emitting diodes, logic gates et al. The fabrication of luminescent materials with adjustable emission color by self-assembly of π-conjugated molecules has attracted particular attention. In this study, we designed and synthesized a thiophene-based α-cyanostyrene-derivative (TPPA), then investigate its self-assembly morphology and fluorescence emission under different organic solvents, different proportions of H2O/THF (DMSO) mixture and different pH conditions by UV, FL and SEM images. It was found that TPPA formed nanoparticles by self-assembly in organic solvent (THF or DMSO), accompanied by strong fluorescence emission. However, with the increase of water ratio, the fluorescence intensity decreased accompany with red shift, and the self-assembly morphology changed from nanoparticles to fibers. More interestingly, when pillar[5]arene (P5) was added to form host-guest complex with TPPA, white light emission could be successfully constructed when the ratio of TPPA to P5 was 1:20 and THF to water was 19:1.
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Affiliation(s)
- Haibo Zhong
- School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai, China
- School of Chemistry and Chemical Engineering, Nantong University, Nantong, China
| | - Liang Li
- School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai, China
- *Correspondence: Liang Li, ; Shajun Zhu, ; Yang Wang,
| | - Shajun Zhu
- Department of Hepatobiliary and Pancreatic Surgery, Affiliated Hospital of Nantong University, Nantong, China
- *Correspondence: Liang Li, ; Shajun Zhu, ; Yang Wang,
| | - Yang Wang
- School of Chemistry and Chemical Engineering, Nantong University, Nantong, China
- *Correspondence: Liang Li, ; Shajun Zhu, ; Yang Wang,
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Li J, Li Z, Liu H, Gong H, Zhang J, Yao Y, Guo Q. Organic molecules with inverted singlet-triplet gaps. Front Chem 2022; 10:999856. [PMID: 36092667 PMCID: PMC9448862 DOI: 10.3389/fchem.2022.999856] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 08/01/2022] [Indexed: 11/13/2022] Open
Abstract
According to Hund’s multiplicity rule, the energy of the lowest excited triplet state (T1) is always lower than that of the lowest excited singlet state (S1) in organic molecules, resulting in a positive singlet-triplet energy gap (ΔEST). Therefore, the up-converted reverse intersystem crossing (RISC) from T1 to S1 is an endothermic process, which may lead to the quenching of long-lived triplet excitons in electroluminescence, and subsequently the reduction of device efficiency. Interestingly, organic molecules with inverted singlet-triplet (INVEST) gaps in violation of Hund’s multiplicity rule have recently come into the limelight. The unique feature has attracted extensive attention in the fields of organic optoelectronics and photocatalysis over the past few years. For an INVEST molecule possessing a higher T1 with respect to S1, namely a negative ΔEST, the down-converted RISC from T1 to S1 does not require thermal activation, which is possibly conducive to solving the problems of fast efficiency roll-off and short lifetime of organic light-emitting devices. By virtue of this property, INVEST molecules are recently regarded as a new generation of organic light-emitting materials. In this review, we briefly summarized the significant progress of INVEST molecules in both theoretical calculations and experimental studies, and put forward suggestions and expectations for future research.
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Affiliation(s)
- Jie Li
- College of Optoelectronic Engineering, Chengdu University of Information Technology, Chengdu, China
| | - Zhi Li
- College of Optoelectronic Engineering, Chengdu University of Information Technology, Chengdu, China
| | - Hui Liu
- College of Optoelectronic Engineering, Chengdu University of Information Technology, Chengdu, China
| | - Heqi Gong
- College of Optoelectronic Engineering, Chengdu University of Information Technology, Chengdu, China
| | - Jincheng Zhang
- College of Optoelectronic Engineering, Chengdu University of Information Technology, Chengdu, China
| | - Yali Yao
- School of Physics and Engineering Technology, Chengdu Normal University, Chengdu, China
| | - Qiang Guo
- College of Optoelectronic Engineering, Chengdu University of Information Technology, Chengdu, China
- *Correspondence: Qiang Guo,
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Dai T, Kiuchi H, Minamide H, Miyake Y, Inoki H, Sonoda Y, Tsutsumi J, Kanai K. Growth and characterization of melem hydrate crystals with a hydrogen-bonded heptazine framework. Phys Chem Chem Phys 2022; 24:13922-13934. [PMID: 35621074 DOI: 10.1039/d2cp00691j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
In carbon nitride (CN) compounds, hydrogen bonds play a major role in cohesion, in addition to dispersion forces. The crystal structures of CN compounds produced via thermal polymerization are complex, but they possess unique and attractive features. Melem is a well-known building unit of CN compounds such as melon and g-C3N4, which have recently attracted attention as photocatalysts. Melem hydrate (Mh) forms hexagonal prismatic crystals that are sufficiently porous to accommodate small molecules. In this study, we grew and characterized single crystals of Mh and investigated their optical properties and hygroscopicity. By precisely adjusting the hydration conditions, we succeeded in growing a well-formed hexagonal prismatic single crystal of Mh (Mhr) with a length measuring several tens of micrometers. Furthermore, we discovered a parallelogram-shaped Mh single crystal (Mhp), which possessed a different crystal structure and optical properties from those of Mh and melem crystals. Although the crystal structure of Mh was greatly disrupted by dehydration, it exhibited hygroscopicity and could absorb moisture even in air, restoring the crystal structure of Mh. In addition, Mh demonstrated a high photoluminescence quantum yield and long lifetime delayed fluorescence, similar to melem crystal. The high quantum yield of Mh can be attributed to the effect of the strong anchoring of the melem molecule by several hydrogen bonds in the Mh crystal, since the strongly anchored molecule is less likely to undergo radiation-free deactivation due to the small displacement of atomic positions in the excited state after light absorption. The findings obtained in this study shed light not only on the application of CN compounds as photocatalysts, but also on a wider range of applications based on their optoelectronic functions.
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Affiliation(s)
- Tomonori Dai
- Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
| | - Hiroki Kiuchi
- Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
| | - Hiroki Minamide
- Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
| | - Yuto Miyake
- Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
| | - Hiroya Inoki
- Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
| | - Yoriko Sonoda
- Research Institute for Advanced Electronics and Photonics, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, 305-8565 Tsukuba, Ibaraki, Japan
| | - Jun'ya Tsutsumi
- Research Institute for Advanced Electronics and Photonics, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, 305-8565 Tsukuba, Ibaraki, Japan
| | - Kaname Kanai
- Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
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10
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Sancho-García JC, Brémond E, Ricci G, Pérez-Jiménez AJ, Olivier Y, Adamo C. Violation of Hund’s rule in molecules: Predicting the excited-state energy inversion by TD-DFT with double-hybrid methods. J Chem Phys 2022; 156:034105. [DOI: 10.1063/5.0076545] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- J. C. Sancho-García
- Department of Physical Chemistry, University of Alicante, E-03080 Alicante, Spain
| | - E. Brémond
- Université de Paris, ITODYS, CNRS, F-75006 Paris, France
| | - G. Ricci
- Laboratory for Computational Modeling of Functional Materials, Namur Institute of Structured Matter, Université de Namur, Rue de Bruxelles, B-5000 Namur, Belgium
| | - A. J. Pérez-Jiménez
- Department of Physical Chemistry, University of Alicante, E-03080 Alicante, Spain
| | - Y. Olivier
- Laboratory for Computational Modeling of Functional Materials, Namur Institute of Structured Matter, Université de Namur, Rue de Bruxelles, B-5000 Namur, Belgium
| | - C. Adamo
- Chimie ParisTech, PSL Research University, CNRS, Institute of Chemistry for Life and Health Sciences (i-CLeHS), FRE 2027, F-75005 Paris, France
- Institut Universitaire de France, 103 Boulevard Saint Michel, F-75005 Paris, France
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11
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Dinkelbach F, Bracker M, Kleinschmidt M, Marian CM. Large Inverted Singlet-Triplet Energy Gaps Are Not Always Favorable for Triplet Harvesting: Vibronic Coupling Drives the (Reverse) Intersystem Crossing in Heptazine Derivatives. J Phys Chem A 2021; 125:10044-10051. [PMID: 34756038 DOI: 10.1021/acs.jpca.1c09150] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Heptazine derivatives are promising dopants for electroluminescent devices. Recent studies raised the question whether heptazines exhibit a small regular or an inverted singlet-triplet (IST) gap. It was argued that the S1 ← T1 reverse intersystem crossing (RISC) is a downhill process in IST emitters and therefore does not require thermal activation, thus enabling efficient harvesting of triplet excitons. Rate constants were not determined in these studies. Modeling the excited-state properties of heptazine proves challenging because fluorescence and intersystem crossing (ISC) are symmetry-forbidden in first order. In this work, we present a comprehensive theoretical study of the photophysics of heptazine and its derivative HAP-3MF. The calculations of electronic excitation energies and vibronic coupling matrix elements have been conducted at the density functional theory/multireference configuration interaction (DFT/MRCI) level of theory. We have employed a finite difference approach to determine nonadiabatic couplings and derivatives of spin-orbit coupling and electric dipole transition matrix elements with respect to normal coordinate displacements. Kinetic constants for fluorescence, phosphorescence, internal conversion (IC), ISC, and RISC have been computed in the framework of a static approach. Radiative S1 ↔ S0 transitions borrow intensity mainly from optically bright E' π → π* states, while S1 ↔ T1 (R)ISC is mediated by E″ states of n → π* character. Test calculations show that IST gaps as large as those reported in the literature are counterproductive and slow down the S1 ← T1 RISC process. Using the adiabatic DFT/MRCI singlet-triplet splitting of -0.02 eV, we find vibronically enhanced ISC and RISC to be fast in the heptazine core compound. Nevertheless, its photo- and electroluminescence quantum yields are predicted to be very low because S1 → S0 IC efficiently quenches the luminescence. In contrast, fluorescence, IC, ISC, and RISC proceed at similar time scales in HAP-3MF.
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Affiliation(s)
- Fabian Dinkelbach
- Institute of Theoretical and Computational Chemistry, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany
| | - Mario Bracker
- Institute of Theoretical and Computational Chemistry, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany
| | - Martin Kleinschmidt
- Institute of Theoretical and Computational Chemistry, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany
| | - Christel M Marian
- Institute of Theoretical and Computational Chemistry, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany
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Li J, Gong H, Zhang J, Liu H, Tao L, Wang Y, Guo Q. Efficient Exciplex-Based Deep-Blue Organic Light-Emitting Diodes Employing a Bis(4-fluorophenyl)amine-Substituted Heptazine Acceptor. Molecules 2021; 26:5568. [PMID: 34577041 PMCID: PMC8466596 DOI: 10.3390/molecules26185568] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 09/03/2021] [Accepted: 09/10/2021] [Indexed: 11/25/2022] Open
Abstract
The realization of a deep-blue-emitting exciplex system is a herculean task in the field of organic light-emitting diodes (OLEDs) on account of a large red-shifted and broadened exciplex emission spectrum in comparison to those of the corresponding single compounds. Herein, 2,5,8-tris(di(4-fluorophenyl)amine)-1,3,4,6,7,9,9b-heptaazaphenalene (HAP-3FDPA) was designed as an electron acceptor by integrating three bis(4-fluorophenyl)amine groups into a heptazine core, while 1,3-di(9H-carbazol-9-yl)benzene (mCP) possessing two electron-donating carbazole moieties was chosen as the electron donor. Excitingly, the exciplex system of 8 wt% HAP-3FDPA:mCP exhibited deep-blue emission and a high photoluminescence quantum yield of 53.2%. More importantly, an OLED containing this exciplex system as an emitting layer showed deep-blue emission with Commission Internationale de l'Eclairage coordinates of (0.16, 0.12), a peak luminance of 15,148 cd m-2, and a rather high maximum external quantum efficiency of 10.2% along with a low roll-off. This study not only reports an efficient exciplex-based deep-blue emitter but also presents a feasible pathway to construct highly efficient deep-blue OLEDs based on exciplex systems.
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Affiliation(s)
- Jie Li
- College of Optoelectronic Engineering, Chengdu University of Information Technology, Chengdu 610225, China; (J.L.); (H.G.); (J.Z.); (H.L.); (L.T.)
| | - Heqi Gong
- College of Optoelectronic Engineering, Chengdu University of Information Technology, Chengdu 610225, China; (J.L.); (H.G.); (J.Z.); (H.L.); (L.T.)
| | - Jincheng Zhang
- College of Optoelectronic Engineering, Chengdu University of Information Technology, Chengdu 610225, China; (J.L.); (H.G.); (J.Z.); (H.L.); (L.T.)
| | - Hui Liu
- College of Optoelectronic Engineering, Chengdu University of Information Technology, Chengdu 610225, China; (J.L.); (H.G.); (J.Z.); (H.L.); (L.T.)
| | - Li Tao
- College of Optoelectronic Engineering, Chengdu University of Information Technology, Chengdu 610225, China; (J.L.); (H.G.); (J.Z.); (H.L.); (L.T.)
| | - Yanqing Wang
- College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, China;
| | - Qiang Guo
- College of Optoelectronic Engineering, Chengdu University of Information Technology, Chengdu 610225, China; (J.L.); (H.G.); (J.Z.); (H.L.); (L.T.)
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