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Light-Emitting Porphyrin Derivative Obtained from a Subproduct of the Cashew Nut Shell Liquid: A Promising Material for OLED Applications
摘要： In this work, the meso-tetra[4-(2-(3-n-pentadecylphenoxy)ethoxy]phenylporphyrin (H2P), obtained from the cashew nut shell liquid (CNSL), and its zinc (ZnP) and copper (CuP) metallic complexes, were applied as emitting layers in organic light emitting diodes (OLEDs). These compounds were characterized via optical and electrochemical analysis and the electroluminescent properties of the device have been studied. We performed a cyclic voltammetry analysis to determine the Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) energy levels for the porphyrins, in order to select the proper materials to assemble the device. H2P and ZnP presented fluorescence emission band in the red region, from 601 nm to 718 nm. Moreover, we verified that the introduction of bulky substituents hinders the π–π stacking, favoring the emission in the film. In addition, the strongest emitter, ZnP, presented a threshold voltage of 4 V and the maximum irradiance of 10 μW cm?2 with a current density (J) of 15 mA cm?2 at 10 V. The CuP complex showed to be a favorable material for the design of OLEDs in the infrared. These results suggest that the porphyrins derived from a renewable source, such as CNSL, is a promising material to be used in organic optoelectronic devices such as OLEDs.
关键词： cashew nut shell liquid,porphyrins,OLEDs,electroluminescence,photoluminescence
更新于2025-11-19 16:46:39
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Photophysicochemical properties and photodynamic therapy activity of chloroindium(III) tetraarylporphyrins and their gold nanoparticle conjugates
摘要： Novel chloroindium(III) complexes of tetra(4-methylthiophenyl)porphyrin (2a) and tetra-2-thienylporphyrin (2b) dyes have been synthesized and characterized. The main goal of the project was to identify fully symmetric porphyrin dyes with Q-band regions that lie partially in the therapeutic window that are suitable for use in photodynamic therapy (PDT). 2a and 2b were found to have fluorescence quantum yield values ≤ 0.01 and moderately high singlet oxygen quantum yields (0.54?0.73) due to heavy atom effects associated with the sulfur and indium atoms. The dark toxicity and PDT activity against epithelial breast cancer cells (MCF-7) were investigated over a dose range of 3.0?40 mg . mL-1. The in vitro dark cytotoxicity of 2a is significantly lower than that of 2b at ≤ 40 mg . mL-1. 2a was conjugated with gold nanoparticles (AuNPs) to form a nanoconjugate (2a-AuNPs), which exhibited a higher singlet oxygen quantum yield (FD) value and PDT activity than was observed for 2a alone. The results suggest that the AuNPs nanoconjugates of readily synthesized fully symmetric porphyrin dyes are potentially suitable for PDT applications, if meso-aryl substituents that provide scope for nanoparticle conjugation can be introduced that shift the Q bands into the therapeutic window.
关键词： porphyrins,photophysics,dark toxicity,singlet oxygen,gold nanoparticles,photodynamic therapy
更新于2025-09-23 15:22:29
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Medium viscosity effect on fluorescent properties of Sn(IV)-tetra(4-sulfonatophenyl)porphyrin complexes in buffer solutions
摘要： Supramolecular triads consisting of hydrophilic Sn(IV)-tetra(4-sulfophenyl)-porphyrin and two axial guests such as propylphenol, tyrosine, and 2-(2-hydroxyphenyl)-benzoxazole were synthesized. The structures of synthesized complexes were identified by experimental spectroscopic and quantum-chemical simulation methods, and their fluorescent properties were studied in various viscosity media (mixed phosphate buffer-glycerin solvents of different composition). The effect of axial ligand structure on the fluorescent properties of these triads (due to the hydrogen bonding or π-π stacking between the components of ?host-guest? systems) is discussed. The potential use of synthesized complexes as environmental probes of local viscosity is proposed.
关键词： synthesis,ROESY,fluorescent properties,hydrogen bonding,DOSY,2D NMR,DFT,viscosity,Sn(IV)-porphyrins
更新于2025-09-23 15:22:29
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Enhanced Raman Scattering by Molecular Nanoaggregates
摘要： The formation of a molecular aggregate in a confined, nanodimensioned region of space leads to what might be termed a 'molecular nanoaggregate'. The present review deals with a theoretical formulation termed 'aggregation-enhanced Raman scattering' (AERS), and its use in discussion of relative Raman band intensities and selection rules for nanoaggregates. AERS represents a concept for discussion of nanoaggregates that is different from those provided by resonance Raman scattering, surface-enhanced Raman scattering and Mie scattering, all of which ignore the impact of aggregation of molecules on Raman scattering. Beyond the theoretical formulation behind the AERS phenomenon, also outlined in this review are representative samples of publications of other authors and researchers using AERS to provide explanations for experimental findings. In addition to clarifying issues regarding the use of nanocomposites involving aggregated molecules, it is found that increasing use of AERS concepts is being made to rationalize Raman spectral observations in a range of other disciplines that fall in both the physical sciences and the medical fields.
关键词： Aggregation,Porphyrins,Nano,Cyanines,Raman
更新于2025-09-23 15:22:29
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Conductive Fused Porphyrin Tapes on Sensitive Substrates by a Chemical Vapor Deposition Approach
摘要： Oxidative polymerization of nickel(II) 5,15-diphenyl porphyrin and nickel(II) 5,15-bis(di-3,5-tert-butylphenyl) porphyrin by an oxidative chemical vapor deposition (oCVD) approach yields multiply fused porphyrin oligomers in thin film form. The oCVD technique enables the formation, deposition and p-doping of conjugated poly(porphyrins) coatings in a single step without the use of solvents or post-treatments. The decisive reactions and side reactions during the oCVD process are evidenced by high-resolution mass spectrometry. Due to the highly conjugated structure of the fused porphyrin tapes the thin films exhibit an electrical conductivity of 3.6×10–2 S·cm–1 and strong absorption in the visible to near-infrared spectral region. The formation of smooth conjugated poly(porphyrins) thin films, even on sensitive substrates, is demonstrated by their successful deposition and patterning on glass, silicon and printer paper. The ability to form conductive poly(porphyrins) thin films could enable the design of a new category of optoelectronic devices using the oCVD approach.
关键词： Chemical Vapor Deposition,Polymerization,Oxidative Coupling,Porphyrins,Thin Films
更新于2025-09-23 15:22:29
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Incremental Introduction of Organocatalytic Activity into Conformationally Engineered Porphyrins
摘要： To study the correlation of macrocycle nonplanarity and catalytic activity of free base porphyrins in detail, a series of six tetraphenylporphyrins with graded degree of β-ethyl substitution ('H2EtxTPPs' 1–6; x = 0, 2, 4, 6, 8) was applied in organocatalyzed reactions. They display incrementally increasing nonplanarity due to repulsive peri-interactions. This creates an out-of-plane vector and better accessibility of the core amine and imine groups as the number of alkyl substituents increases. Following such a molecular engineering approach, the inner core system could be used to activate small molecules as a result of significant saddle distortion. The potential organocatalyst 'H2EtxTPPs' were used in benchmark sulfa-Michael reactions and we found a distinct relationship between nonplanarity and conversion. These observations were attributed to the combined effect of enhanced basicity and increased H-bonding potential that could facilitate bifunctional organocatalysis. Ultimately, density functional theory (DFT) calculations were performed on 1–6 to monitor some electronic properties of the title compounds.
关键词： porphyrins,organocatalysis,hydrogen bonds,molecular engineering,macrocycles
更新于2025-09-23 15:22:29
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Investigation into the Oxygen-Involved Electrochemiluminescence of Porphyrins and Its Regulation by Peripheral Substituents/Central Metals
摘要： We provide evidence of oxygen-involved electrochemiluminescence (ECL) of metal-free porphyrins and metalloporphyrins firstly. O2?? and OH?, that are oxygen intermediates, are indispensable for the formation of excited porphyrins, which has been proven by trapping free radical strategies. The wide differences regarding emission location and mechanism between metal-free porphyrins [including meso-tetra(4-methoxyphenyl)porphine (H2TMPP), meso-tetraphenylporphyrin (H2TPP) and meso-tetra(4-carboxyphenyl)porphine (H2TCPP)] and metalloporphyrins (MTPP) depend on whether protons are present in the center of the porphin ring. Besides, the oxygen-involved ECL of porphyrins can be controlled regularly by peripheral substituents with different polarities. Because of the stretched molecular structure and the decrease in electron density around the protons located at porphin ring; electron-withdrawing groups are more conducive to protons being attacked by O2??, as well as the enhancement of porphyrins ECL. The ECL efficiency [ФECL, which is normalized with respect to Ru(bpy)3(PF6)2 (taking ФECL of Ru(bpy)3(PF6)2 = 1 )] is gradually improved from H2TMPP (ФECL = 0.16), H2TPP (ФECL = 2.20) to H2TCPP (ФECL = 3.83); and the ФECL = 4.21 of Zn(II)TPP is significantly higher than other MTPP [e.g. Co(II)TPP and Cu(II)TPP]. A deeper understanding regarding the improvement of porphyrins ECL efficiency and new application towards porphyrins-related devices can be achieved from this work.
关键词： electrochemiluminescence,oxygen intermediates,central metals,porphyrins,peripheral substituents
更新于2025-09-23 15:22:29
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Applications of Molecular Spectroscopy to Current Research in the Chemical and Biological Sciences || Geometric and Electronic Properties of Porphyrin and its Derivatives
摘要： In this chapter, we discuss protonation and substitution effects on the absorption spectra of porphyrin molecules based on density functional theory (DFT) and time-dependent DFT calculations. The results of the calculations are compared with experimental data. The calculations show that protonation of core nitrogen atoms of porphyrin and meso-substituted porphyrins produces a substantial shift in Soret and Q-absorption bands, relative to their positions in corresponding nonprotonated and nonsubstituted chromophores. A relaxed potential energy surface (RPES) scan has been utilized to calculate ground and excited state potential energy surface (PES) curves as functions of the rotation of one of the meso-substituted sulfonatophenyl groups about dihedral angles θ (corresponding to Cα─Cm─C?─C) ranging from 40 to 130°, using 10° increments. The ground state RPES curve indicates that when the molecule transitions from the lowest ground state to a local state, the calculated highest potential energy barrier at the dihedral angle of 90° is only 177 cm?1. This finding suggests that the meso-sulfonatophenyl substitution groups are able to rotate around Cm─C? bond at room temperature because the thermal energy (kBT) at 298 K is 207.2 cm?1. Furthermore, the calculations show that the geometric structure of the porphyrin is strongly dependent on protonation and the nature of the meso-substituted functional groups.
关键词： DFT calculation,protonation,PES,porphyrins,absorption
更新于2025-09-23 15:21:21
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Porphyrins as Photoredox Catalysts in Csp2-H Arylations: Batch and Continuous Flow Approaches
摘要： We have investigated both batch and continuous flow photoarylations of enol-acetates to yield different α-arylated aldehyde and ketone building blocks by using diazonium salts as the aryl-radical source. Different porphyrins were used as SET photocatalysts, and photophysical as well as electrochemical studies were performed to rationalize the photoredox properties and suggest mechanistic insights. Notably, the most electron-deficient porphyrin (meso-tetra(pentafluorophenyl)porphyrin) shows the best photoactivity as an electron-donor in the triplet excited-state, which was rationalized by the redox potentials of excited states and the turnover of the porphyrins in the photocatalytic cycle. Scope, a two-step continuous protocol and multigram-scale reactions are also presented revealing a robust, cost-competitive and easy methodology, highlighting the significant potential of porphyrins as SET photocatalysts.
关键词： Diazonium Salts,Photoredox Catalysts,Porphyrins,Batch and Continuous Flow,Csp2-H Arylations
更新于2025-09-23 15:21:01
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An Insight Into the Potentiation Effect of Potassium Iodide on aPDT Efficacy
摘要： Antimicrobial photodynamic therapy (aPDT) is gaining a special importance as an effective approach against multidrug-resistant strains responsible of fatal infections. The addition of potassium iodide (KI), a non-toxic salt, is recognized to increase the aPDT efficiency of some photosensitizers (PSs) on a broad-spectrum of microorganisms. As the reported cases only refer positive aPDT potentiation results, in this work we selected a broad range of porphyrinic and non-porphyrinic PSs in order to gain a more comprehensive knowledge about this aPDT potentiation by KI. For this evaluation were selected a series of meso-tetraarylporphyrins positively charged at meso positions or at β-pyrrolic positions and the non-porphyrinic dyes Methylene blue, Rose Bengal, Toluidine Blue O, Malachite Green and Crystal Violet; the assays were performed using a bioluminescent E. coli strain as a model. The results indicate that KI has also the ability to potentiate the aPDT process mediated by some of the cationic PSs [Tri-Py(+)-Me, Tetra-Py(+)-Me, Form, RB, MB, Mono-Py(+)-Me, β-ImiPhTPP, β-ImiPyTPP, and β-BrImiPyTPP] allowing a drastic reduction of the treatment time as well as of the PS concentration. However, the efficacy of some porphyrinic and non-porphyrinic PSs [Di-Py(+)-Me opp, Di-Py(+)-Me adj, Tetra-Py, TBO, CV, and MG] was not improved by the presence of the coadjuvant. For the PSs tested in this study, the ones capable to decompose the peroxyiodide into iodine (easily detectable by spectroscopy or by the visual appearance of a blue color in the presence of amylose) were the most promising ones to be used in combination with KI. Although these studies confirmed that the generation of 1O2 is an important fact in this process, the PS structure (charge number and charge position), aggregation behavior and affinity for the cell membrane are also important features to be taken in account.
关键词： cationic porphyrins,xanthenes,potassium iodide,phenothiazines,bioluminescent E. coli,antimicrobial photodynamic therapy
更新于2025-09-23 15:21:01