Molecular structure, fluorescent properties and dynamics of excited state structural relaxation of the oxadiazolic ortho -analog of POPOP with the additional sterical hindrance

Дорошенко, А. О.; Kyrychenko, Alexander; Баумер, В. Н.; Verezubova, A. A.; Ptyagina, L. M.

doi:10.1016/s0022-2860(00)00405-1

Cited by 13 publications

(10 citation statements)

References 13 publications

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“…For the compounds studied here, it is observed that the C¼N and C-O bonds increase in length while the N-N bond lengths shorten in all molecules. The calculated bond lengths agree well with the range found in literature [9,10,14,[34][35][36][37][38][39][40][41][42][43][44][45], i.e. C-O: 1.357-1.383 Å ; C¼N: 1.280-1.304 Å ; N-N: 1.382-1.405 Å .…”

Section: Structural Parameterssupporting

confidence: 87%

“…Well, the molecules studied here are composed of two or three coplanar rings what is consistent with an extended -electronic system. Such geometrical arrangement is confirmed also by known structural studies on similar 1,3,4-oxadiazoles [9,10,14,[34][35][36][37][38][39][40][41][42][43][44][45]. Therefore, small changes in the molecular structure of the oxadiazoles (except the ring substituents) do not have any influence on the planarity of the molecules.…”

Section: Structural Parameterssupporting

confidence: 71%

“…The crystallographic data for the various 2,5-disubstituted 1,3,4-oxadiazoles [9,10,14,[34][35][36][37][38][39][40][41][42][43][44][45] show that the C-O, C¼N and N-N bond lengths vary in ranges 1.348-1.374; 1.269-1.303; 1.394-1.417 Å , respectively. Comparison between these derivatives and the unsubstituted 1,3,4-oxadiazole shows tendency in alternation of structural parameters.…”

Section: Structural Parametersmentioning

confidence: 99%

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1,3,4-oxadiazoles: evaluation of aromaticity and atomic charge distribution

Malek¹,

Zborowski²,

Gebski³

et al. 2008

Molecular Physics

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The aromaticity and atomic charge distribution were investigated for the mono-and disubstituted 1,3,4-oxadiazoles. Using an electron density-based approach (B3LYP), the structures of the molecules were estimated, then the changes of -electron delocalization of the heterocyclic ring were estimated based on geometric (HOMA) as well as magnetic properties (NICS). Aromaticity of the oxadiazole ring varies to some extend depending on the electron character of the substituent, however, the two methods do not correlate well. The HOMA approach suggests a non-aromatic character for the oxadiazole ring, while NICS predicts a relatively high aromaticity. Additionally, two computational methodologies were used for quantitative measures of atomic charges, i.e. AIM and GAPT. Results of these computations reveal accumulation of electron density inside the heterocyclic ring due to substitution by the aryl groups and its significant removal in the presence of the imino group. However, both procedures suggest different explanation of this fact.

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Section: Structural Parameterssupporting

confidence: 87%

Section: Structural Parameterssupporting

confidence: 71%

Section: Structural Parametersmentioning

confidence: 99%

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1,3,4-oxadiazoles: evaluation of aromaticity and atomic charge distribution

Malek¹,

Zborowski²,

Gebski³

et al. 2008

Molecular Physics

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“…Generally, enlarged fluorescence Stokes shifts are typical to 1,3,5-triphenyl-substituted pyrazolines and pyrazoles (see section 3.2). Definite excited state structural relaxation processes could be among the reasons of such behavior, which make the initially unplanar unexcited molecule more planar and more conjugated in its fluorescent S 1 -state [56][57][58][59]. This results in additional decrease of the energy of structurally relaxed excited state and corresponding Stokes shift enlargement.…”

Section: Methodsmentioning

confidence: 99%

1,5-Diaryl-3-Benzimidazolyl-2-Pyrazolines and Pyrazoles – Novel Fluorescent Dyes of Pyrazoline Family

Kotlyar¹,

Orlov²,

Grygorovych³

et al. 2017

Chemical Series

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A series of novel aryl derivatives of 2-pyrazoline bearing 2-benzimidazolyl moiety was synthesized via condensation of corresponding chalcones with phenyl hydrazine. Pyrazoles on their background were obtained by the optimized oxidation procedure with manganese dioxide in benzene. Fluorescent characteristics of the title compounds were determined for their solutions in acetonitrile. Quantum-chemical modeling of molecular structure, UV/Vis spectra, electron density redistribution and structural relaxation at electronic excitation resulting in high fluorescence Stokes shifts were conducted as well.

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“…The dihedral angles between the (I)/(II), (II)/(III) and (I)/(III) planes are 4.80 (15), 3.46 (16) and 7.49 (15) , respectively, indicating the near coplanarity of the three rings. A search of the Cambridge Structural Database (Version of November 2003;Allen, 2002) found four comparable 2,5-diphenyl-1,3,4oxadiazoles: 2-(5-phenyl-1,3,4-oxadiazol-2-yl)-benzoic acid (Smith et al, 1983); 1-(5-phenyl-2-oxazolyl)-2-(5-(2 Hmethoxy)phenyl-1,3,4-oxadiazol-2-yl)benzene (Doroshenko et al, 2000); bis(N-tosyl-l-leucine) 2,5-bis(o-aminophenyl)-1,3,4-oxadiazole diamide (Zhao et al, 2000); 2-(4-(4-(N,Nbis(2-(acetoxy)ethyl)amino)phenylazo)phenyl)-5-(4-nitrophenyl)-(1,3,4)-oxadiazole (Carella et al, 2002). The bond lengths and angles of the oxadiazole moiety in the title molecule are in good agreement with those in these four structures.…”

Section: Commentmentioning

confidence: 99%