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Báez-Grez R, Rios RP. Is azulene's local aromaticity and relative stability driven by the Glidewell-Lloyd rule? Phys Chem Chem Phys 2024; 26:12162-12167. [PMID: 38590242 DOI: 10.1039/d4cp00091a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2024]
Abstract
The local aromaticity of azulene has been studied to understand their electronic properties. For this purpose, we have used the magnetic criterion through magnetically induced current density maps, ring current strengths, NICSzz(1), and the bifurcation value of three-dimensional surfaces of NICSzz. On the other hand, the delocalization criterion was used by calculating the MCI and ELFπ. The results show that the five-membered ring (5-MR) is more aromatic than the seven-membered ring (7-MR) and more aromatic than the free C5H5- ring. The opposite case is seen for the seven-membered ring, which is less aromatic than the free C7H7+. The local aromatic rings in azulene are formed due to an intramolecular electron transfer from the 7-MR to the 5-MR. In addition, the proposed resonance structures that allow explaining the properties of azulene, such as the dipole moment or the relative stability (in comparison to other isomers), show a preference for the formation of 5-MRs; for this reason, it is possible to conclude that the aromaticity and relative stability of azulene is driven by the Glidewell-Lloyd rule.
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Affiliation(s)
- Rodrigo Báez-Grez
- Facultad de Ciencias, Universidad Arturo Prat, Casilla 121, Iquique 1100000, Chile
| | - Ricardo Pino Rios
- Centro de Investigación Medicina de Altura - CEIMA, Universidad Arturo Prat. Casilla 121, Iquique 1100000, Chile.
- Química y Farmacia, Facultad de Ciencias de la Salud, Universidad Arturo Prat, Casilla 121, Iquique 1100000, Chile
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2
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Cummings E, Karadakov PB. Aromaticity in the Electronic Ground and Lowest Triplet States of Molecules with Fused Thiophene Rings. Chemistry 2024; 30:e202303724. [PMID: 38038597 DOI: 10.1002/chem.202303724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 11/30/2023] [Accepted: 12/01/2023] [Indexed: 12/02/2023]
Abstract
Analysis of the variations of the off-nucleus isotropic magnetic shielding, σiso(r), around thiophene, thienothiophenes, dithienothiophenes and sulflowers in their electronic ground (S0) and lowest triplet (T1) states reveals that some of the features of aromaticity and bonding in these molecules do not fit in with predictions based on the popular Hückel's and Baird's rules. Despite having 4n π electrons, the S0 states of the sulflowers are shown to be aromatic, due to the local aromaticities of the individual thiophene rings. To reduce its T1 antiaromaticity, the geometry of thiophene changes considerably between S0 and T1: In addition to losing planarity, the carbon-carbon two 'double' and one 'single' bonds in S0 turn into two 'single' and one 'double' bonds in T1. Well-defined Baird-style aromaticity reversals are observed between the S0 and T1 states of only three of the twelve thiophene-based compounds investigated in this work, in contrast, the sulflower with six thiophene rings which is weakly aromatic in S0 becomes more aromatic in T1. The results suggest that the change in aromaticity between the S0 and T1 states in longer chains of fused rings is likely to affect mostly the central ring (or the pair of central rings); rings sufficiently far away from the central ring(s) can retain aromatic character.
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Affiliation(s)
- Edward Cummings
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
| | - Peter B Karadakov
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
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3
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Yan K, Hu Z, Yu P, He Z, Chen Y, Chen J, Sun H, Wang S, Zhang F. Ultra-photostable small-molecule dyes facilitate near-infrared biophotonics. Nat Commun 2024; 15:2593. [PMID: 38519530 PMCID: PMC10960032 DOI: 10.1038/s41467-024-46853-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Accepted: 03/12/2024] [Indexed: 03/25/2024] Open
Abstract
Long-wavelength, near-infrared small-molecule dyes are attractive in biophotonics. Conventionally, they rely on expanded aromatic structures for redshift, which comes at the cost of application performance such as photostability, cell permeability, and functionality. Here, we report a ground-state antiaromatic strategy and showcase the concise synthesis of 14 cationic aminofluorene dyes with mini structures (molecular weights: 299-504 Da) and distinct spectra covering 700-1600 nm. Aminofluorene dyes are cell-permeable and achieve rapid renal clearance via a simple 44 Da carboxylation. This accelerates optical diagnostics of renal injury by 50 min compared to existing macromolecular approaches. We develop a compact molecular sensing platform for in vivo intracellular sensing, and demonstrate the versatile applications of these dyes in multispectral fluorescence and optoacoustic imaging. We find that aromaticity reversal upon electronic excitation, as indicated by magnetic descriptors, not only reduces the energy bandgap but also induces strong vibronic coupling, resulting in ultrafast excited-state dynamics and unparalleled photostability. These results support the argument for ground-state antiaromaticity as a useful design rule of dye development, enabling performances essential for modern biophotonics.
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Affiliation(s)
- Kui Yan
- Department of Chemistry, State Key Laboratory of Molecular Engineering of Polymers, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials and iChem, Fudan University, Shanghai, PR China
| | - Zhubin Hu
- State Key Laboratory of Precision Spectroscopy, School of Physics and Electronic Science, East China Normal University, Shanghai, PR China
| | - Peng Yu
- Department of Chemistry, State Key Laboratory of Molecular Engineering of Polymers, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials and iChem, Fudan University, Shanghai, PR China
| | - Zuyang He
- Department of Chemistry, State Key Laboratory of Molecular Engineering of Polymers, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials and iChem, Fudan University, Shanghai, PR China
| | - Ying Chen
- Department of Chemistry, State Key Laboratory of Molecular Engineering of Polymers, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials and iChem, Fudan University, Shanghai, PR China
| | - Jiajian Chen
- Department of Breast Surgery, Key Laboratory of Breast Cancer in Shanghai, Fudan University Shanghai Cancer Center, Shanghai, PR China
| | - Haitao Sun
- State Key Laboratory of Precision Spectroscopy, School of Physics and Electronic Science, East China Normal University, Shanghai, PR China.
| | - Shangfeng Wang
- Department of Chemistry, State Key Laboratory of Molecular Engineering of Polymers, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials and iChem, Fudan University, Shanghai, PR China.
| | - Fan Zhang
- Department of Chemistry, State Key Laboratory of Molecular Engineering of Polymers, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials and iChem, Fudan University, Shanghai, PR China.
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4
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Xiao L, Wang S, Wang Y, Wang B, Ji C, Lin X, Liang H, Zhang S, Xu X, Dong L. Density functional theory studies on the oleic acid thermal oxidation into volatile compounds. Food Chem X 2023; 19:100737. [PMID: 37780285 PMCID: PMC10534075 DOI: 10.1016/j.fochx.2023.100737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 05/27/2023] [Accepted: 06/01/2023] [Indexed: 10/03/2023] Open
Abstract
Oleic acid oxidation is one of the main sources of food flavor compounds. Volatile profiling was investigated using thermal desorption cryo-trapping combined with gas chromatography-mass spectrometry to analyze the volatile composition of oleic acid oxidation. A total of 43 volatile compounds, including aldehydes (11), ketones (2), alcohols (5), furans (2), acids (8), ester (12) and alkane (3) were identified from oleic acid during heating. Then, density functional theory (DFT) was applied to analyze the oxidative mechanism of oleic acid during heating. A total of 30 reactions were obtained and grouped into the peroxide (ROOH), alkoxy radical (RO•), and peroxide radical (ROO•) pathways. The structures of intermediates, transition states (TS), and products in each reaction were also determined. Results show that the branch chemical reactions were the key reactions in different reaction pathway. Moreover, the reaction priority of the thermal oxidation reaction of oleic acid was the peroxide radical mechanism > the peroxide mechanism > the alkoxy radical mechanism.
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Affiliation(s)
- Lin Xiao
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, Liaoning, China
- China Resources Snow Beer, Beijing 100000, Beijing, China
| | - Shang Wang
- School of Biotechnology, Dalian Polytechnic University, Dalian 116034, Liaoning, China
| | - Yi Wang
- School of Biotechnology, Dalian Polytechnic University, Dalian 116034, Liaoning, China
| | - Binchen Wang
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, Liaoning, China
- National Engineering Research Center of Seafood, Dalian 116034, Liaoning, China
| | - Chaofan Ji
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, Liaoning, China
- National Engineering Research Center of Seafood, Dalian 116034, Liaoning, China
| | - Xinping Lin
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, Liaoning, China
- National Engineering Research Center of Seafood, Dalian 116034, Liaoning, China
| | - Huipeng Liang
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, Liaoning, China
- National Engineering Research Center of Seafood, Dalian 116034, Liaoning, China
| | - Sufang Zhang
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, Liaoning, China
- National Engineering Research Center of Seafood, Dalian 116034, Liaoning, China
| | - Xianbing Xu
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, Liaoning, China
- National Engineering Research Center of Seafood, Dalian 116034, Liaoning, China
| | - Liang Dong
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, Liaoning, China
- National Engineering Research Center of Seafood, Dalian 116034, Liaoning, China
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Santos CV, Monteiro SA, Soares ASC, Souto ICA, Moura RT. Decoding Chemical Bonds: Assessment of the Basis Set Effect on Overlap Electron Density Descriptors and Topological Properties in Comparison to QTAIM. J Phys Chem A 2023; 127:7997-8014. [PMID: 37703453 DOI: 10.1021/acs.jpca.3c04504] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/15/2023]
Abstract
Quantum chemical bonding descriptors based on the total and overlap density can provide valuable information about chemical interactions in different systems. However, these descriptors can be sensitive to the basis set used. To address this, different numerical treatments of electron density have been proposed to reduce the basis set dependency. In this work, we introduce overlap properties (OPs) obtained through numerical treatment of the electron density and present the topology of overlap density (TOP) for the first time. We compare the basis set dependency of numerical OP and TOP descriptors with their quantum theory of atoms in molecules (QTAIM) counterparts, considering the total electron density. Three single (C-C, C-O, and C-F) bonds in ethane, methanol, and fluoromethane and two double (C═C and C═O) bonds in ethene and formaldehyde were analyzed. Diatomic molecules Li-X with X = F, Cl, and Br were also analyzed. Eight parameters, including QTAIM descriptors and OP/TOP descriptors, are used to assess the basis dependency at the ωB97X-D level of theory using 28 basis sets from three classes: Pople, Ahlrichs, and Dunning. The study revealed that the topological overlap electron density properties exhibit comparatively lesser dependence on the basis set compared to their total electron density counterparts. Remarkably, these properties retain their chemical significance even with reduced basis set dependency. Similarly, numerical OP descriptors show less basis set dependency than their QTAIM counterparts. The excess of polarization functions increases charge concentration in the interatomic region and influences both QTAIM and OP descriptors. The basis sets Def2TZVP, 6-31++G(d,p), 6-311++G(d,p), cc-pVDZ, cc-pVTZ, and cc-pVQZ demonstrate reduced variability for the tested bond classes in this study, with particular emphasis on the triple-ζ quality Ahlrichs' basis set. We recommend against using basis sets with numerous polarization functions, such as augmented Dunning's and Ahlrichs' quadruple-ζ.
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Affiliation(s)
- Carlos V Santos
- Department of Chemistry, Federal University of Paraiba, Joao Pessoa, Paraiba 58051-970, Brazil
| | - Shirlene A Monteiro
- Department of Chemistry, State University of Paraiba, Campina Grande, Paraiba 58051-970, Brazil
| | - Amanda S C Soares
- Department of Chemistry and Physics, Center of Agrarian Sciences, Federal University of Paraiba, Areia, Paraiba 58397-000, Brazil
| | - Isabeli C A Souto
- Department of Chemistry and Physics, Center of Agrarian Sciences, Federal University of Paraiba, Areia, Paraiba 58397-000, Brazil
| | - Renaldo T Moura
- Department of Chemistry and Physics, Center of Agrarian Sciences, Federal University of Paraiba, Areia, Paraiba 58397-000, Brazil
- Computational and Theoretical Chemistry Group (CATCO), Department of Chemistry, Southern Methodist University, Dallas, Texas 75275, United States
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Wang B, Wang S, Wang Y, Zhang S, Lin X, Xu X, Ji C, Liang H, Dong L. Deep exploration of lipid oxidation into flavor compounds: A density functional theory study on (E)-2-decenal thermal oxidative reaction. Food Chem 2023; 428:136725. [PMID: 37399695 DOI: 10.1016/j.foodchem.2023.136725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Revised: 06/20/2023] [Accepted: 06/24/2023] [Indexed: 07/05/2023]
Abstract
Unsaturated fatty aldehydes are the main products of fatty acid oxidation, and could be further oxidized to form volatile compounds with shorter carbon chains. Therefore, studying the oxidation of unsaturated fatty aldehydes is an important way to reveal the mechanism of food flavor formation during heating. In this study, volatile profiling of (E)-2-decenal during heating was firstly investigated by using thermal-desorption cryo-trapping combined with gas chromatography-mass spectrometry (GC-MS). A total of 38 volatile compounds were detected. Then, twenty-one reactions in the heating process of (E)-2-decenal were obtained by using density functional theory (DFT) calculations, and grouped into three oxidation pathways, namely, peroxide pathway, peroxyl radical pathway and alkoxy radical pathway. Meanwhile, the priority of these three pathways was the alkoxy radical reaction pathway > peroxide pathway > peroxyl radical reaction pathway. Moreover, the calculated results agreed well with the experimental results.
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Affiliation(s)
- Binchen Wang
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, Liaoning, China; National Engineering Research Center of Seafood, Dalian 116034, Liaoning, China
| | - Shang Wang
- School of Biotechnology, Dalian Polytechnic University, Dalian 116034, Liaoning, China
| | - Yi Wang
- School of Biotechnology, Dalian Polytechnic University, Dalian 116034, Liaoning, China
| | - Sufang Zhang
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, Liaoning, China; National Engineering Research Center of Seafood, Dalian 116034, Liaoning, China
| | - Xinping Lin
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, Liaoning, China; National Engineering Research Center of Seafood, Dalian 116034, Liaoning, China
| | - Xianbing Xu
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, Liaoning, China; National Engineering Research Center of Seafood, Dalian 116034, Liaoning, China
| | - Chaofan Ji
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, Liaoning, China; National Engineering Research Center of Seafood, Dalian 116034, Liaoning, China
| | - Huipeng Liang
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, Liaoning, China; National Engineering Research Center of Seafood, Dalian 116034, Liaoning, China
| | - Liang Dong
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, Liaoning, China; National Engineering Research Center of Seafood, Dalian 116034, Liaoning, China.
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7
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Okazawa K, Tsuji Y, Yoshizawa K. Frontier Orbital Views of Stacked Aromaticity. J Phys Chem A 2023. [PMID: 37243683 DOI: 10.1021/acs.jpca.3c00360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Recent studies have theoretically and experimentally demonstrated that antiaromatic molecules with 4n π electrons exhibit stacked aromaticity according to π-π stacking when arranged in a face-to-face manner. However, the mechanism of its occurrence has not been clearly studied. In this study, we investigated the mechanism of stacked aromaticity using cyclobutadiene. When the antiaromatic molecules are stacked in a face-to-face manner, the orbital interactions between the degenerate singly occupied molecular orbitals (SOMOs) of the monomer unit cause a larger energy gap between the degenerate highest-occupied molecular orbitals (HOMOs) and the lowest-unoccupied molecular orbitals (LUMOs) of the dimer. However, the antiaromatic molecules are more stable in less symmetric conformations, mainly because of pseudo-Jahn-Teller distortions. In the case of cyclobutadiene, the two SOMOs of the monomer unit split into HOMO and LUMO because of the bond alternation. When the molecules are stacked in a face-to-face manner, the HOMO-LUMO gap of the dimer is smaller than that of the monomer due to the interactions between the HOMOs and LUMOs of the two monomer units. When the monomer units are within a specific distance of each other, the HOMO and LUMO of the dimer, which correspond to antibonding and bonding between the units, respectively, are interchanged. This alternation of molecular orbitals may result in an increase in the bond strength between the monomer units, exhibiting stacked aromaticity. We demonstrated that it is possible to control the distance exhibited by stacked aromaticity by engineering the HOMO-LUMO gap of the monomer units.
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Affiliation(s)
- Kazuki Okazawa
- Institute for Materials Chemistry and Engineering and IRCCS, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan
| | - Yuta Tsuji
- Faculty of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan
| | - Kazunari Yoshizawa
- Institute for Materials Chemistry and Engineering and IRCCS, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan
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Levina EO, Tsirelson VG. DFT potentials from a chemical perspective: Anatomy of electron (de)localization in molecules and crystals. J Comput Chem 2023. [PMID: 37183763 DOI: 10.1002/jcc.27131] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 04/26/2023] [Accepted: 04/28/2023] [Indexed: 05/16/2023]
Abstract
We introduce a fermionic potential, v f $$ {v}_f $$ , as a comprehensive measure of electron (de)localization in atomic-molecular systems. Unlike other common descriptors as ELF, LOL, etc., it characterizes all physical effects responsible for (de)localization of electrons, namely: an exchange hole depth, its tendency to change, a sensitivity of an exchange correlation hidden in a pair density and kinetic potential to local variations in electron density. Wells in the v f $$ {v}_f $$ distribution correspond to the domains of maximum electron localization, while the potential's barriers prevent delocalization of electrons through them. It also estimates bond orders and successfully reveals the impact of chemical modifications or environmental effects on the delocalization of electrons in molecules and crystals. The v f $$ {v}_f $$ components provide a unique opportunity to compare the influence of the mentioned physical effects on electron (de)localization. This merges physical and chemical views of electron delocalization using functions appearing in density functional theory.
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Affiliation(s)
- Elena O Levina
- N.S. Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, Moscow, Russia
| | - Vladimir G Tsirelson
- D.I. Mendeleev University of Chemical Technology, Moscow, Russia
- Federal Research Centre "Fundamentals of Biotechnology" of the Russian Academy of Sciences, Moscow, Russia
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Pedersen J, Mikkelsen KV. A Benchmark Study of Aromaticity Indexes for Benzene, Pyridine, and the Diazines - II. Excited State Aromaticity. J Phys Chem A 2023; 127:122-130. [PMID: 36548541 DOI: 10.1021/acs.jpca.2c07059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In this work, one geometrical aromaticity index and four electron sharing indexes are benchmarked for their application in excited state aromaticity calculations. Two computationally feasible and reliable procedures are identified, namely, CAM-B3LYP/cc-pVTZ and ωB97X-D/cc-pVTZ. Topological effects on the first excited singlet and triplet electronic manifold were investigated, and the latter was in general found to display more aromatic character compared to the S1 surface. Besides, geometrical relaxation on each of the manifolds was observed to hamper the aromaticity, thereby resulting in more antiaromatic character. The relative order of excited state aromaticity within the studied molecules was noted to resemble the reversed version of the relative order of ground state aromaticity. Thereby, the following generalization was postulated: The more aromatic a molecule is in its ground state, the more antiaromatic it will be in its electronic first excited manifolds.
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Affiliation(s)
- Jacob Pedersen
- Department of Chemistry, University of Copenhagen, CopenhagenDK-2100, Denmark.,Department of Chemistry, Technical University of Denmark, Kongens LyngbyDK-2800, Denmark
| | - Kurt V Mikkelsen
- Department of Chemistry, University of Copenhagen, CopenhagenDK-2100, Denmark
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10
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Ntui TN, Oyo-Ita EE, Agwupuye JA, Benjamin I, Eko IJ, Ubana EI, Etiowo KM, Eluwa EC, Imojara A. Synthesis, Spectroscopic, DFT Study, and Molecular Modeling of Thiophene-Carbonitrile Against Enoyl-ACP Reductase Receptor. CHEMISTRY AFRICA 2022. [DOI: 10.1007/s42250-022-00544-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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11
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Plasmonic Surface of Metallic Gold and Silver Nanoparticles Induced Fluorescence Quenching of Meso-Terakis (4-Sulfonatophenyl) Porphyrin (TPPS) and Theoretical-Experimental Comparable. J Fluoresc 2022; 32:2257-2269. [PMID: 36045307 PMCID: PMC9606071 DOI: 10.1007/s10895-022-03022-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 08/24/2022] [Indexed: 11/09/2022]
Abstract
Colloidal metallic nanoparticles have attracted a lot of interest in the last two decades owing to their simple synthesis and fascinating optical properties. In this manuscript, a study of the effect of both gold nanoparticles (Au NPs) and silver nanoparticles (Ag NPs) on the fluorescence emission (FE) of TPPS has been investigated utilizing steady-state fluorescence spectroscopy and UV–Vis spectrophotometry. From the observed electronic absorption spectra, there is no evidence of the ground state interaction between metallic Au NPs or Ag NPs with TPPS. On the other side, the FE spectra of TPPS have been quenched by both Ag and Au NPs. Via applying quenching calculations, Ag NPs showed only traditional static fluorescence quenching of TPPS with linear Stern–Volmer (SV) plots. On the contrary, quenching of TPPS emission by Au NPs shows composed models. One model is the sphere of action static quenching model that prevails at high quencher concentrations leading to non-linear SV plots with positive deviation. However, at low Au NPs concentrations, traditional dynamic quenching occurs with linear SV plots. The quantum calculations for TPPS structure have been obtained using Gaussian 09 software: in which the TPPS optimized molecular structure was achieved using DFT/B3LYP/6-311G (d) in a gaseous state. Also, the calculated electronic absorption spectra for the same molecule in water as a solvent are obtained using TD/M06/6-311G + + (2d, 2p). Furthermore, the theoretical and experimental results comparable to UV–Vis spectra have been investigated.
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