Phenanthroimidazole Derivatives Research Articles

Reversible mechanoresponsive luminescence based on an unsymmetrical D-π-A type phenanthroimidazole derivative

Abstract A kind of D-π-A mechanoresponsive luminescent molecule 2- (4- (1H-phenanthro[9,10-d] imidazol) benzylidene) malononitrile (ANPPI) was synthesized and characterized by UV absorption, photoluminescence, and other techniques. The obvious mechanoresponsive properties of ANPPI were reversible upon grinding and fuming, and were demonstrated by X-ray diffraction, scanning electron microscopy, and differential scanning calorimetry.

Film thickness dependent color purity of WOLEDs in a Phenanthroimidazole derivative due to electromers

Recently, derivatives of Phenanthroimidazole (Phen-I) based small molecules have been synthesized for OLED applications. Their photophysical characterization revealed they were fluorescent with a high quantum yield, indicating their suitability as an emissive layer (EML) in OLEDs. In this paper, we report and compare the OLED performance of two Phen-I derivatives. One contains thiophene (compound 1), and the other, newly designed and synthesized, has perylene (compound 2) as a functional group. Devices of 1 with lower EML thickness (∼70 nm) showed bluish white emission, while devices with higher EML thickness (> ∼100 nm) showed color tunability from bluish-white (CIE co-ordinates: (0.26, 31)) light at lower voltage to almost pure white (CIE co-ordinates: (0.29, 32)) light at higher voltages forming WOLED. The WOLED formed for 1 at all thickness of the EML is attributed to the combined monomer and electromer emission. In addition, the voltage-dependent change in colour purity observed for higher EML thickness is attributed to increased electromer species, indicating stronger intermolecular interactions due to well-connected grains in their thin films. In contrast, devices of compound 2 showed yellow-orange emission independent of the thickness of the EML. The optimized geometry for all devices was ITO/PEDOT: PSS /NPD/1 or 2 /BPhen/LiF-Al. Devices of 2 were more efficient than those of 1, indicating that forming electromers, though advantageous in giving WOLEDs, reduces the device efficiency.

Extremely Low Threshold Quasi‐CW Amplified Spontaneous Emission Achieving and Its Mechanism Study

AbstractThe development of lasing materials with weak pile‐up effect from triplet excitons, low lasing threshold, and long operational lifetime is much significant for truly continuous wave operation and electrically pumping organic lasers. However, most of organic gain media has been verified to have extreme quenching effect from triplet excitons due to its wide‐band distribution of triplet absorption spectrum. Here, it is found that the phenanthroimidazole derivatives as gain media have congenital advantages on handling triplet's issues. A very low amplified spontaneous emission (ASE) threshold of 0.56 µJ cm−2 and a long operational lifetime of 5.77 × 105 pump pulses in air atmosphere are well obtained. When increasing the pump repetition frequency from 20 Hz to 20 kHz, the operational lifetimes of the thin films have small reduction. Under a high pump repetition frequency of 200 kHz, which is quasi‐continuous wave operational regime, the PI2PhDPO thin film exhibits very low ASE threshold of 0.78 µJ cm−2 due to the tiny overlap between triplet absorption and ASE spectra.

Versatile deep blue fluorescent materials based on the hybridization of phenanthroimidazole and fluorene derivatives

Blue fluorescent materials are an essential part of commercial OLED displays and lightings. However, the market lacks highly efficient, short-emission wavelength blue fluorescent materials. Herein, two new blue fluorescent materials, SAFPI-3 and SAFPI-2, are developed based on a phenanthroimidazole derivative and spiro fluorene triphenylamine by replacing the substitution sites, which tactfully utilize the spatial configuration of the molecules to achieve higher external quantum efficiency and a shorter emission wavelength at the same time. Furthermore, the versatility of SAFPI-3 and SAFPI-2 can be demonstrated as non-doped emitters for blue OLEDs and as the hosts of yellow phosphorescent OLEDs, which have achieved a high external quantum efficiency of 23.98% with extremely low-efficiency roll-off.

Organic Fluorescent Compounds Based on Phenanthroimidazole: A Review on Highlights Studies.

Organic compounds containing phenanthroimidazole; Its optical, thermal, chemical, and high fluorescence have drawn the interest of numerous researchers. Phenanthroimidazole derivatives are appealing for various applications owing to these characteristics. This research provides a summary of the general information contained in studies on the synthesis, characterisation, photophysical characteristics, and possible applications of phenanthroimidazole derivative compounds. The focus of this study revolves around these topics' utilization in technological fields such sensors, solar cells, optical brighteners, and OLED, which covers significant studies on mentioned topics. We anticipate that this study is meant to provide an outline for researchers aiming to further examine fluorescent organic compounds for technological innovations. Furthermore, we anticipate that this research will be crucial in developing long term high organic compounds for optoelectronic devices.

Progress on Phenanthroimidazole Derivatives for Light-Emitting Electrochemical Cells: An Overview

Phenanthroimidazole derivatives are currently frequently used chemical compounds in the active layers of various devices, such as organic light-emitting diodes (OLEDs) or light-emitting electrochemical cells (LECs). Their advantages include simple and cheap synthesis, good solubility in organic solvents, easy processing, high thermal stability, excellent electron transport ability, and very good optical and electroluminescent properties. The construction of the LEC is based on a very simple construction in which the active layer plays a significant role. Thus, the compounds used in it are extremely important because they play the role of more than just emitters. This review summarizes the current state of the art regarding phenanthroimidazole derivatives used in the active layer in LECs. The synthesis of the considered compounds is presented in detail in the first part of the review. Next, research on the physicochemical properties of phenanthroimidazole derivatives is presented. Finally, the latest reports on LEC test devices are presented.

Rational design of phenanthroimidazole derivatives with hybridized local and charge-transfer characteristics to achieve efficient blue emission in non-doped OLEDs

Two new blue phenanthroimidazole-based emitters were designed and synthesized. The molecules after introducing a benzene ring show interesting HLCT characteristics. A HLCT-OLED shows blue emission and a full width at half-maximum of 67 nm.

Crystalline organic thin films for crystalline OLEDs (II): weak epitaxy growth of phenanthroimidazole derivatives.

The ordered molecular arrangement of crystalline organic semiconductors facilitates high carrier mobility and light emission in organic light-emitting diode (OLED) devices. It has been demonstrated that the weak epitaxy growth (WEG) process is a valuable crystallization route for fabricating crystalline thin-film OLEDs (C-OLEDs). Recently, C-OLEDs based on crystalline thin films of phenanthroimidazole derivatives have exhibited excellent luminescent properties such as high photon output at low driving voltage and high power efficiency. Achieving effective control of organic crystalline thin film growth is crucial for the development of new C-OLEDs. Herein, we report the studies on morphology structure and growth behavior of the phenanthroimidazole derivative WEG thin films. The oriented growth of WEG crystalline thin films is determined by channeling and lattice matching between the inducing layer and active layer. Large-size and continuous WEG crystalline thin films can be obtained by controlling the growth conditions.

Imidazole-based phenanthroline derivatives induce DNA damage-mediated apoptosis to suppress hepatocellular carcinoma

ObjectiveThis study focused on designing and subsequently screening novel phenanthroimidazole derivatives with activity as potential inhibitors of hepatocellular carcinoma. MethodsWe synthesized a series of phenanthroimidazole derivatives and their molecular structures were characterized by ESI-MS and 1H NMR. The anti-tumor activity was evaluated using the MTT assay. The potential mechanism of anti-tumor activity based on DNA-damage-mediated apoptosis was analyzed by flow cytometry, immunofluorescence, and comet assay. Additionally, the anti-angiogenic activity was assessed by transgenic zebrafish. Furthermore, in vivo biodistribution of the compound was studied using a nude mice xenograft model. ResultsThe screening results for anti-tumor activity revealed that the compounds, especially 2, exhibited promising restrain activity against the growth of HepG2 cells with an IC50 value of 0.68 µM. Further studies showed that 2 can accumulate in the mitochondria of HepG2 cells, decreased the mitochondrial membrane potential, induce DNA damage and apoptosis of cells. Moreover, it was also discovered that 2 can inhibit the formation of neovascularization, which was confirmed by the decrease in ISV angiogenesis of zebrafish after being incubated with 2, as well as the decrease in the number and length of tubes formed in HUVECs cells. Besides, in vivo distribution and metabolism studies show that 2 is rapidly distributed in the whole body and accumulated in the tumor tissue of BALB/c mice. ConclusionTaken together, this type of phenanthroimidazole derivatives, especially 2, will be developed to be potent inhibitors against the growth of HepG2 cells through anti-angiogenesis and apoptosis based on mitochondrial-dependent pathways in the near future.

Enhanced blue-emissive electroluminescence performance with rational donor substitution

High performance blue emitters with nice color purity are highly desired in the commercialization of organic light-emitting diodes (OLEDs). Herein, two blue-emissive hybridized local and charge-transfer (HLCT) phenanthroimidazole (PPI) derivatives were designed and synthesized. Comparing to the 9,9-dimethyl-9,10-dihydroacridine (DMAC) substituted DPCN, the 10H-spiro[acridine-9,9′-fluorene] (SAF) substituted SPCN demonstrates higher photoluminescence quantum yield (PLQY) and improved radiative transition rate (kr). With the same device structure, despite that SPCN and DPCN show similar electroluminescence (EL) spectra, the EL efficiency of SPCN is about 1.5 times that of DPCN. Especially the non-doped OLED based on SPCN, the maximum external quantum efficiency (EQE) is 7.1%, which is a competitive result among the conventional blue-emissive fluorescent emitters. More importantly, this work provides a general strategy to achieve high performance blue/deep-blue OLED by rational donor optimization.

Voltage tunable white light generation from combined emission of monomer and electromer in phenanthroimidazole based OLED

Phenanthroimidazole (Phen-I) derivatives have been studied for applications in materials science and organic electronics. We recently reported the synthesis and photophysical properties of phenanthroimidazole (Phen-I) derivatives showing strong emission in the blue region. In this work, OLED device properties of two of the Phen-I derivatives are studied and compared. In these Phen-I derivatives, the N1 position is substituted by phenyl ring and the C2 position by benzothienyl in 1 and pyridyl in 2. Devices of 1,2 were made in the following geometry ITO/PEDOT:PSS/NPD/1 or 2/BPhen/LiF-Al. The electroluminescence (EL) spectrum for the device of 1 showed two main peaks centered at 495 and 620 nm. Intensity of peak centered at 620 nm increased with an increase of applied voltage. The device of 2 showed a single electroluminescent peak at 530 nm, found to be voltage independent. The voltage dependent emission at 620 nm observed in devices of 1 is attributed to the formation of an electromer indicating strong intermolecular interactions. Strong intermolecular interaction in 1 is also evident from our morphological studies in thin films showing the formation of meso-aggregates. Devices with the geometry of ITO/PEDOT:PSS/NPD/1/TPBi/LiF-Al gave the most efficient devices with a current efficiency of 4.6 Cd/A at a current density of 50 mA/cm2. Interestingly, devices operated at low voltage gave bluish-white emission but at 24 V it produced pure white electroluminescence having CIE coordinates of (0.30, 0.35). Thus, our results show that depending on the functional group attached to the imidazole ring, thin film forming properties change. This helps to enhance intermolecular interactions resulting in an additional electromer emission leading to white OLED devices.

Smartly engineered “off-on” switchable probe: For the recognition of toxic analytes in semi-aqueous medium

The pyrene moiety successfully serves as a source of ratiometric changes as well as electron acceptor. Thus pyrene ring has been introduced to phenanthroimidazole to the optical response towards different metal ions and anions. Phenanthroimidazole derivative bearing pyrene group found to be a ratiometric sensor for Hg2+/Al3+ ions. Hg2+ ions and Al3+ ions having least detection limit of 10 μM and F− ions having least detection limit value of 0.5 μM. Interestingly, probe exhibited a selective, enhanced ratiometric fluorescence change, colrometric change and “off- on” behavior with F- ions among the different anions in semi aqueous media and contribute to the formation of AND gate.

Unveiling the Full Potential of 2-aryl-1H-phenanthro [9,10-d] imidazoles as Cytotoxic Agents vs AGS, HepG2 and MCF-7 Cell lines

A few 2-aryl-1H-phenanthro [9,10-d] imidazoles were synthesized and assessed for their cytotoxicity against MCF-7, HepG2, and AGS cell lines using MTT assay. Cellular assessments showed that phenanthroimidazoles were extremely potent cytotoxic agents (sub-nanomolar IC50s). Maximum effect was recorded for para-N-phenyl acetamide containing derivative against AGS cells (IC50=0.07 nM). It was also revealed that phenanthroimidazole derivatives showed better cytotoxicity against MCF-7 and AGS cells when compared to HepG2 cells. Minimum cytotoxicity was reported for para-methylphenyl derivative within HepG2 cancer cells (IC50 7608.07 nM). Structure activity relationship studies indicated that incorporation of nitrogen/oxygen containing polar groups such as N-acetyl or nitro into para/meta positions of phenyl ring significantly enhanced the cytotoxicity against AGS cells. Similar trend was observed in meta-nitro derivatives vs MCF-7 cells. It was revealed that even the least potent compound exhibited cytotoxic activity in the range of low micromolar IC50. Results of this study proposed 2-aryl-1H-phenanthro [9,10-d] imidazoles as privileged structures for further in vivo studies.

Fabrication of Titanium Dioxide Nanoparticles Using Sunflower Leaf Extract and Their Applications Towards the Synthesis and Biological Evaluation of Some Novel Phenanthro Imidazole Derivatives

Plant-mediated synthesis of nanomaterials has been increasingly practiced day by day due to its eco-friendly nature, simple method without using any hazardous chemicals and solvent. In the present study, we synthesized Titanium dioxide nanomaterials (TiO2 NPs) using sunflower leaves extract. The synthesized TiO2 NPs was confirmed by ultraviolet-visible (UV-Vis) spectroscopy, while morphology and size of the NPs were identified by Scanning Electron Microscopy (SEM); elemental composition of materials analyzed by using Energy Dispersive X-ray (EDAX) analysis, and functional groups in plant extract identified by using Fourier Transform Infrared Spectroscopy (FTIR) analysis responsible for reducing and stabilizing of NPs, crystalline nature of NPs identification by using X-ray diffraction analysis (XRD), colloidal solution stability, the thermal stability of NPs noticed by dynamic light scattering (DLS) and thermo-gravimetric analyses. The synthesized green catalyst TiO2 NPs mediated novel Phenenthro [9,10-d imidazole derivatives(9a-e) have been successfully synthesized with good yields by reacting to 3-methyl-5-phenoxy-1-phenyl-1H-pyrazole-4-carbaldehydes with 9,10-phenanthrene quinone and ammonium acetate. The structures of the synthesized molecules were characterized by NMRspectroscopy. The fluorescence property of the synthesized molecules (9a-e) in acetonitrile solvent was studied, and all the compounds showed good emission intensity. An in-silico molecular docking was performed on the synthesized molecules (9a-e) using aldose reductase as a target protein. Overall, studies indicate that compounds (9a-e)are promising in developing novel anti-diabetic drugs in the future. The synthesized molecules (9a-e) were further screened for antioxidant activity by DPPH radical scavenging method.

Rational Molecular Design of Multifunctional Blue-Emitting Materials Based on Phenanthroimidazole Derivatives.

High-performance deep-blue emitters with external quantum efficiencies (EQEs) exceeding 5 % are still scarce in organic light-emitting diodes (OLEDs). In this work, by introducing a [1,2,4]triazolo[1,5-a] pyridine (TP) unit at the N1 position of phenanthroimidazole (PI), two luminescent materials, PTPTPA and PTPTPA, were obtained. Systematic photophysical analysis showed that the TP block is suitable for constructing hybridized local and charge-transfer (HLCT) emitters. Its moderate electron-withdrawing ability and rigid planar structure can enhance the CT component while ensuring color purity. In addition, compared with PTPTPA, the additional phenyl ring of PTPBPTA not only increased the oscillator strength, but also decreased the Stokes shift. TDDFT calculations pointed out facile reverse intersystem crossing processes in PTPTPA from high-lying triplet states to the singlet excited state. A nondoped device based on PTPTPA as emitter showed impressive performance with EQEmax of 7.11 % and CIE coordinates of (0.15, 0.09). At the same time, it was also an efficient host for yellow and red phosphorescent OLEDs. By doping yellow (PPYBA) and red (BTPG) phosphorescent dyes into PTPTPA, a white OLED with a high EQE of 23.85 % was achieved. The successful design of PTPTPA not only provided an optimization choice for OLED emitters, but also demonstrated the empirical rules for the design of multifunctional deep-blue emitters.

Cover Feature: Rational Molecular Design of Multifunctional Blue‐Emitting Materials Based on Phenanthroimidazole Derivatives. (Chem. Eur. J. 25/2021)

Cover Feature: Rational Molecular Design of Multifunctional Blue‐Emitting Materials Based on Phenanthroimidazole Derivatives. (Chem. Eur. J. 25/2021)

Mechanochromism and Aggregation-Induced Emission in Phenanthroimidazole Derivatives: Role of Positional Change of Different Donors in a Multichromophoric Assembly.

Organic materials possessing solid-state emission responsive to external stimuli have significance in a variety of material, biomedical, and optoelectronic applications. Organic molecules having different donor-acceptor architectures integrated with aggregation-induced emission (AIE) fluorophores have been utilized in development of mechanofluorochromic (MFC) materials. In this work, we have designed and synthesized phenanthroimidazole (PI) based derivatives TPE-PI-1, TPE-PI-2, TPE-PI-3, PTZ-PI-1, PTZ-PI-2, and PTZ-PI-3 where in donors tetraphenylethylene-TPE (D) and phenothiazine-PTZ (D') of contrasting donor abilities are attached to the N and C atom positions of PI. The position and mode of attachment of the donors have been changed, and an additional PTZ spacer has been introduced which has a direct consequence on their photophysical and electronic properties. The PI derivatives manifest AIE, solvatochromic, and mechanochromic behavior. The single crystal X-ray analysis of TPE-PI-1 and PTZ-PI-2 reveals bent structures for the PTZ unit and a twisted conformation for TPE moieties. The density functional theory calculations were used to obtain optimized ground-state structures of the PI derivatives. The work shows a comprehensive comparison of the photophysical, electronic, AIE, and MFC properties of the PI derivatives as an effect of variations in the position of donor, donor-acceptor strength, and change in molecular conformation on use of spacer.

Synthesis of a new 1,3,4-thiadiazole-substituted phenanthroimidazole derivative, its growth on glass/ITO as a thin film and analysis of some surface and optoelectronic properties

A novel phenanthroimidazole derivative with p-type conductivity was prepared and fabricated as a heterostructure, exhibiting a negative differential resistance and photodiode properties.

Enhanced emission under proton stimuli based on a phenanthroimidazole derivative by switching the excited state type from the CT to the LE state

We report a vertical D–A molecule showing rare off–on TFA-fuming stimuli responsiveness via changing the excited state from the charge transfer (CT) state to the localized excited (LE) state.

Smart luminescent molecular europium complexes and their versatile applications

A series of smart luminescent Eu(iii) complexes (C1 = Eu(DBM)3ligand 1, C2 = Eu(DBM)3ligand 2, C3 = Eu(DBM)3ligand 3, C4 = Eu(DBM)3 ligand 4, C5 = Eu(DBM)3ligand 5) were synthesized by using C1-functionalized phenanthro-imidazole derivatives as the neutral ligands and dibenzoylmethanate (DBM) as the anionic ligand.