Synthesis and spectral comparison of electronic and molecular properties of some hydrazines and hydrazyl free radicals

Patrascu, Bianca; Lete, Cecilia; Popescu, Codruța C.; Matache, Mihaela; Păun, Andrei; Mădălan, Augustin M.; Ioniță, Petre

doi:10.24820/ark.5550190.p011.119

Cited by 7 publications

(9 citation statements)

References 17 publications

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“…Most of the hydrazyl free radicals have a violet color, while the parent hydrazines are yellow; the corresponding anion is usually red-brown, but it is possible also to be green, depending on the substituents. All these acid-base or redox processes are reversible, as shown in Figure 4 [17]. To make easier the work with such structures, in this paper a free radical will be indicated by numbers (i.e., 1), while the parent hydrazine will be noted as 1-H; similarly, the parent hydrazine of DPPH • free radical will be noted as DPPH-H.…”

Section: Dpph • Free Radicalmentioning

confidence: 99%

“…Table 2. λ max (nm), pK a , E ox (V) and bond dissociation energy (BDE) values (kcal/mol) for selected compounds [17,27,39,46,56,61]. All these redox or acid-base processes can be followed by color change [62].…”

Section: Application Of Hydrazyls 41 Acid-base and Redox Processesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Chemistry of DPPH· Free Radical and Congeners

Ioniță

2021

IJMS

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Since the discovery in 1922 of 2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl stable free radical (DPPH·), the chemistry of such open-shell compounds has developed continuously, allowing for both theoretical and practical advances in the free radical chemistry area. This review presents the important, general and modern aspects of the chemistry of hydrazyl free radicals and the science behind it.

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Section: Dpph • Free Radicalmentioning

confidence: 99%

Section: Application Of Hydrazyls 41 Acid-base and Redox Processesmentioning

confidence: 99%

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The Chemistry of DPPH· Free Radical and Congeners

Ioniță

2021

IJMS

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“…In particular, we addressed a greater and more worthwhile question about domain adaption: are we able to reproduce the success of ML-ωPBE on radicals? Herein we performed a similar performance assessment for ML-ωPBE based on 64 new species, including 35 carbon-based radicals (C), 19, 2 polyaromatic hydrocarbon-based radicals (PAH), 63,198 13 nitrogen-based radicals (N), [199][200][201][202][203][204][205][206][207] 6 nitrogen-oxygen-based radicals (NO), [208][209][210][211][212][213] and 8…”

Section: Doublet Radicalsmentioning

confidence: 99%

Accurate Electronic and Optical Properties of Organic Doublet Radicals Using Machine Learned Range-Separated Functionals

Shen

French

et al. 2023

Preprint

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Luminescent organic semiconducting doublet-spin radicals are unique and emergent optical materials because their fluorescent quantum yields (Φfl) are not compromised by spin-flipping intersystem crossing (ISC) into any dark high-spin states. The multi-configurational nature of radical electronic structures challenges computational studies in the framework of single-reference density functional theory (DFT) and introduces room for method improvement. In the present study, we extended our earlier development of a machine-learned range-separated hybrid functional, referred to as ML-ωPBE, from closed-shell molecules to doublet-spin radicals, and assessed its performance for the original training set of 3,926 organic semiconducting molecules and an external test set of 64 organic semiconducting radicals from five categories. Interestingly, for this external test set, ML-ωPBE reproduced the optimal value of ω, the molecule-dependent range-separation parameter, from the first-principles OT-ωPBE functional with a small mean absolute error (MAE) of 0.0197 a0−1 and with a significant save of computational cost by 2.46 orders of magnitude. This result demonstrated excellent generalizability and transferability of ML-ωPBE among a variety of organic semiconducting species. To further assess the predictive power of ML-ωPBE on organic semiconducting radicals, we also compared its performance on experimentally measurable absorption and fluorescence energies (Eabs’s and Efl’s), evaluated using time-dependent DFT (TDDFT), with nine conventional functionals. ML-ωPBE reproduced experimental Eabs’s and Efl’s for most radicals in questions, with small MAEs of 0.222 and 0.121 eV, marginally worse from OT-ωPBE. Our work not only illustrated a successful extension of stacked ensemble machine learning (SEML) framework from closed-shell molecules to open-shell doublet-spin radicals, but also opened the venue for the calculations of optical properties these using single-reference TDDFT.

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“…We designed and synthesized hydrazone derivatives not only for antimicrobial studies. Hydrazones are of general wide interest not only in medicinal chemistry [1][2][3][4][5][6] but also in material chemistry, [7][8][9][10][11][12][13][14][15][16] the compounds exhibit nematicidal and insecticidal activity. 17 N-pentafluorophenyl substituted hydrazones can also be used as analytical reagents.…”

Section: Introductionmentioning

confidence: 99%

Two Compounds of 1-((4-Bromothiophen-2-Yl)Methylene)-2-(Perfluorophenyl)Hydrazine, and 1-((4-Bromo-5-Methylthiophen-2-Yl)Methylene)-2-(Perfluorophenyl)Hydrazine and They Crystal, Molecular and Electronic Properties

Sivý¹,

Bortňák²,

Végh³

et al. 2021

Preprint

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The crystals, C11H4BrF5N2S, (I), 1-((4-bromothiophen-2-yl)methylene)-2-(perfluorophenyl)hydrazine and C12H6BrF5N2S, (II), 1-((4-bromo-5-methylthiophen-2-yl)methylene)-2-(perfluorophenyl)hydrazine are molecules with two rings and hydrazone part like a centre of the molecule. The compounds have been synthesized and characterized by elemental, spectroscopic (1H-NMR) analysis. The crystal structures of the solid phase were determined by single crystal X-ray diffraction method. They crystallize in the monoclinic space group with Z = 4 and Z = 2 molecules per unit-cell. The compound (I) crystallizes as a racemate in the centrosymmetric space group and the compound (II) crystallizes as a non-racemate in the non-centrosymmetric space group. The “absolute configuration and conformation for bond values” were derived from the anomalous dispersion (ad) for (II). The crystal structures are revealed diverse non-covalent interactions such as intra- and interhydrogen bonding, π-ring···π-ring, C-H···π-ring and they were investigated. The expected stereochemistry of hydrazones atoms C7, N2 and N1 were confirmed for (I) and (II). The hole molecule of the (I), and (II) possesses “a boat conformation” like a 6-membered ring. The results of the single crystal studies are reproduced with the help of Hirshfeld surface study and Gaussian software.

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Synthesis and spectral comparison of electronic and molecular properties of some hydrazines and hydrazyl free radicals

Cited by 7 publications

References 17 publications

The Chemistry of DPPH· Free Radical and Congeners

The Chemistry of DPPH· Free Radical and Congeners

Accurate Electronic and Optical Properties of Organic Doublet Radicals Using Machine Learned Range-Separated Functionals

Two Compounds of 1-((4-Bromothiophen-2-Yl)Methylene)-2-(Perfluorophenyl)Hydrazine, and 1-((4-Bromo-5-Methylthiophen-2-Yl)Methylene)-2-(Perfluorophenyl)Hydrazine and They Crystal, Molecular and Electronic Properties

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