215-64-5Relevant academic research and scientific papers
Modulated emission from dark triplet excitons in aza-acene compounds: fluorescence versus phosphorescence
Chen, Jianwei,Chen, Yi,Wu, Yishi,Wang, Xuedong,Yu, Zhenyi,Xiao, Lu,Liu, Yanping,Tian, He,Yao, Jiannian,Fu, Hongbing
, p. 1864 - 1871 (2017)
In the field of organic light-emitting diodes (OLEDs), research interests focus on making the optically dark triplet excitons shine in order to increase the electro-optic conversion efficiency of devices. In this work, two kinds of phenazine compounds, i.e. dibenzo[a,c]phenazine (DBP) and tribenzo[a,c,i]phenazine (TBP), were synthesized and used as model compounds to regulate the emission efficiency of the dark triplet excitons by chemical modification. Charge-transfer induced ultrafast intersystem crossing (CT-ISC) with a time constant of ～1 ps was observed for these two phenazine derivatives upon photoexcitation with a high triplet yield of 77.1% for DBP and 58.7% for TBP. The triplet excited states of DBP can produce ultra-long phosphorescence with lifetime as long as 318 ms at 77 K. The quantum yield for phosphorescence (ΦP) is determined to be 8.45%. In sharp contrast, the triplet-excited 3TBP* undergoes an efficient reverse intersystem crossing (RISC) process, resulting in bright delayed fluorescence emission with negligible phosphorescence. A controllable luminescence behavior from the triplet states between fluorescence and phosphorescence in phenazine derivatives is demonstrated. Theoretical calculations reveal that the structure-dependent triplet evolution is due to the charge-transfer induced energy level alignment within these compounds. Our results may have potential applications in the design of OLEDs and high triplet yield pure organic materials.
Ternary Emission of Fluorescence and Dual Phosphorescence at Room Temperature: A Single-Molecule White Light Emitter Based on Pure Organic Aza-Aromatic Material
Zhou, Changjiang,Zhang, Shitong,Gao, Yu,Liu, Haichao,Shan, Tong,Liang, Xiaoming,Yang, Bing,Ma, Yuguang
, (2018)
Herein, a simple aza-aromatic compound dibenzo[a,c]phenazine (DPPZ), which exhibits single-molecule white light with a ternary emission, consisting of simultaneous fluorescence (S1→S0) and dual room-temperature phosphorescence (RTP, T2→S0 and T1→S0) is reported. The Commission Internationale de l' éclairage coordinates of DPPZ powder are (0.28, 0.33). To everyone's knowledge, this is the first case to achieve single-molecule white emission with ternary emission of fluorescence and dual RTP. This finding provides a prototype strategy to realize low-cost, stable pure organic single-molecule white light emission with three standard primary colors through further precise modulation of excited states.
Use of co-grinding as a solvent-free solid state method to synthesize dibenzophenazines
Carlier, Leslie,Baron, Michel,Chamayou, Alain,Couarraze, Guy
, p. 4686 - 4689 (2011)
Many synthetic methods exist for dibenzoquinoxalines but only a few for dibenzophenazines and their aza derivatives and even less are 'green'. Some dibenzophenazines and dibenzopyridoquinoxaline have been efficiently obtained with good to excellent yield by a very simple method which does not require use of solvent or catalyst. Solid phase synthesis using co-grinding presents thus many advantages in developing greener synthetic organic pathways.
A general method for the synthesis of structurally diverse quinoxalines and pyrido-pyrazine derivatives using camphor sulfonic acid as an efficient organo-catalyst at room temperature
Kaur, Gurpreet,Singh, Arvind,Kaur, Navdeep,Banerjee, Bubun
, p. 1121 - 1131 (2021)
A mild, convenient, eco-friendly, general and practical approach has been developed for the synthesis of a series of structurally diverse quinoxaline derivatives via the condensation reactions of various 1,2-diaminobenzene derivatives and 1,2-dicarbonyls
Electron-transfer reorganization energies of isolated organic molecules
Amashukeli, Xenia,Winkler, Jay R.,Gray, Harry B.,Gruhn, Nadine E.,Lichtenberger, Dennis L.
, p. 7593 - 7598 (2002)
He I photoelectron spectra of phenanthrene (1), 1,10-phenanthroline (2), phenazine (3), dibenzo[a,c]anthracene (4), dibenzo[a,c]phenazine (5), and dipyrido[3,2-a;2′3′-c]phenazine (6) have been obtained. Assignment of the π ionization states was aided by electronic structure calculations: the first ionization state of 1, 2B1(π1), is observed at 7.888 ± 0.002 eV, 2B2(π1) of 2 is at 8.342 ± 0.002 eV, and 2B1g(π1) of 3 is at 8.314 ± 0.002 eV. Spectra of 4-6 are reported for the first time: 2A2(π1) of 4 is at 7.376 ± 0.002 eV, and both 5 (7.983 ± 0.002 eV) and 6 (8.289 ± 0.002 eV) exhibit quasi-degenerate first and second ionization states. Quantum-mechanical reorganization energies, λQM, were extracted from analyses of vibrational structure: values are 149 ± 5 (1), 167 ± 5 (2), 68 ± 2 (3), and 92 ± 4 (4) meV. Low-frequency modes were treated semiclassically: values of λSC are estimated to be 21 ± 1 (1), 13 ± 1 (2), 22 ± 1 (3), 66 ± 1 (4), 27 ± 9 (5), and 16 ± 1 (6) meV. Reorganization energies (λ = λQM + λSC) of isolated molecules are 170 ± 5 (1), 180 ± 5 (2), 90 ± 2 (3), and 158 ± 4 (4) meV. Density functional calculations (B3LYP/6-311G++(d,p)) give λ values that are on average 63 meV lower than experimentally derived energies.
Ring Closure of Heterocyclic Systems by Potassium-Graphite Intercalat - C8K
Tamarkin, Dov,Cohen, Yoram,Rabinovitz, Mordecai
, p. 196 - 197 (1987)
Potassium-graphite intercalate C8K is the reagent of choice for the ring closure of the dianions of 2,3-diarylquinoxalines derivatives 1-3 to the dianions of dibenzophenazine derivatives 4-6 in high yields and high degree of purity.This process appears to occur via a thermal electrocyclic process of the dianions.
Synthesis and photophysical properties of three ladder-type chromophores with large and rigid conjugation structures
Zhang, Kaichen,Dai, Yong,Zhang, Xinfu,Xiao, Yi
, p. 1 - 5 (2014)
Three novel ladder-conjugated chromophores indicated as LT1–LT3 were synthesized and characterized. Further studies on linear, nonlinear optics and electrochemical properties demonstrated their photophysical features respectively. Compound LT1 shows good two-photon absorption cross-section (δ) up to?～1200?GM at 810?nm in tetrahydrofuran, which is attributed to intramolecular charge transfer effect, as supported by density functional theory theoretical calculations. Compound LT2 and LT3 show considerable molar extinction coefficients, which are more than 105, and higher quantum yields. Structure–function relationship is further discussed, suggesting a rational strategy to develop ladder-conjugated small molecules.
Green Hydrothermal Synthesis of Fluorescent 2,3-Diarylquinoxalines and Large-Scale Computational Comparison to Existing Alternatives
Amaya-García, Fabián,Caldera, Michael,Koren, Anna,Kubicek, Stefan,Menche, J?rg,Unterlass, Miriam M.
, p. 1853 - 1863 (2021/04/02)
Here, the hydrothermal synthesis (HTS) of 2,3-diarylquinoxalines from 1,2-diketones and o-phenylendiamines (o-PDAs) was achieved. The synthesis is simple, fast, and generates high yields, without requiring any organic solvents, strong acids or toxic catalysts. Reaction times down to 90 % in all cases). Moreover, it was shown that HTS has high compatibility: (i) hydrochlorides, a standard commercial form of amines, could be used directly as combined amine source and acidic catalyst, and (ii) Boc-diprotected o-PDA could be directly employed as substrate that underwent HT deprotection. A systematic large-scale computational comparison of all reported syntheses of the presented quinoxalines from the same starting compounds showed that this method is more environmentally friendly and less toxic than all existing methods and revealed generic synthetic routes for improving reaction yields. Finally, the application of the synthesized compounds as fluorescent dyes for cell staining was explored.
In water organic synthesis: Introducing itaconic acid as a recyclable acidic promoter for efficient and scalable synthesis of quinoxaline derivatives at room temperature
Tamuli, Kashyap J.,Nath, Shyamalendu,Bordoloi, Manobjyoti
supporting information, p. 983 - 1002 (2021/02/27)
Substituted quinoxaline derivatives are traditionally synthesized by co-condensation of various starting materials. Herein, we describe a novel environmentally benign in water synthetic route for the synthesis of structurally and electronically diverse ninety quinoxalines with readily available substituted o-phenylenediamine and 1,2-diketones using cheap and biodegradable itaconic acid as a mild acid promotor in 1 hours. The reaction is performed at room temperature, which proceeds through cyclo-condensation reaction followed by obtaining the aforesaid nitrogen-containing heterocyclic adducts without performing the column chromatography up to 96% total yields. The simplicity, high efficiency, and reusable of the catalyst merits this reaction condition as “green synthesis” which enables it to be useful in synthetic transformations upto gram scale level.
BSA-encapsulated cyclometalated iridium complexes as nano-photosensitizers for photodynamic therapy of tumor cells
Xu, Yao,Wang, Xiang,Song, Kang,Du, Jun,Liu, Jinliang,Miao, Yuqing,Li, Yuhao
, p. 15323 - 15331 (2021/05/19)
Photodynamic therapy is a promising treatment method. The development of suitable photosensitizers can improve therapeutic efficacy. Herein, we report three iridium complexes (Ir1, Ir2, and Ir3), and encapsulate them within bovine serum albumin (BSA) to f
