Experimental and theoretical charge density distribution in Pigment Yellow 101

Du, Jonathan J.; Váradi, Linda; Tan, Jinlong; Zhao, Yiliang; Groundwater, Paul W.; Platts, James Alexis; Hibbs, David E.

doi:10.1039/c4cp04302b

Cited by 12 publications

(16 citation statements)

References 29 publications

(33 reference statements)

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“…Refer to Table S13 in supplementary data for the ADPs used. As can be seen from Table 1, there is very little to separate the Exp and SH_D refinements, in a similar fashion to recent experiences 30,31 with calculated hydrogen ADPs in multipole refinements, the SH_D refinement was not able to locate critical points of some intramolecular hydrogen bonds and so the topological analysis will be based on the Exp refinement.…”

Section: Anisotropic Temperature Factor Refinement Of Hydrogen Atomsmentioning

confidence: 87%

A comparison of the experimental and theoretical charge density distributions in two polymorphic modifications of piroxicam

Lai

Williams

et al. 2016

Phys. Chem. Chem. Phys.

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Experimental charge density distribution studies of two polymorphic forms of piroxicam, β-piroxicam (1) and piroxicam monohydrate (2), were carried out via high-resolution single crystal X-ray diffraction experiments and multipole refinement. The asymmetric unit of (2) consists of two discrete piroxicam molecules, (2a) and (2b), and two water molecules.Geometry differs between (1) and (2) due to the zwitterionic nature of (2) which results in the rotation of pyridine ring around the C(10)-N(2) bond by approximately 180°. Consequently, the pyridine and amide are no longer co-planar and (2) forms two exclusive, strong hydrogen bonds, H(3) …O (4) and that for (2) is -571 kJ mol -1 , which is in agreement with the experimentally determined observations of higher solubility and dissolution rates of (1) compared to (2).3

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Section: Anisotropic Temperature Factor Refinement Of Hydrogen Atomsmentioning

confidence: 87%

A comparison of the experimental and theoretical charge density distributions in two polymorphic modifications of piroxicam

Lai

Williams

et al. 2016

Phys. Chem. Chem. Phys.

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“…The large discrepancies here may be attributed to the inability of the experimental model to properly account for the valence electrons of heavy atoms such as sulfur, further compounded by the proximity of two oxygen atoms which may also contribute to a large amount of unaccounted for electrons. Thus, very small differences in the total electron density, of the same magnitude as the residual errors stemming from the multipole model, are amplified in the Laplacian into apparently major discrepancies between experiment and theory 23,24,43 . It should be noted here that there is no appreciable difference between the Exp and the Shade refinements, across all datasets the maximum differences are 0.30eÅ -3 for ρ bcp and -1.5 eÅ -5 in ł 2 ρ bcp .…”

Section: Topological Analysismentioning

confidence: 99%

An analysis of the experimental and theoretical charge density distributions of the piroxicam–saccharin co-crystal and its constituents

Váradi

Williams

et al. 2016

RSC Adv.

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Experimental and theoretical charge density analyses of piroxicam (1), saccharin (2) and their 1:1 co-crystal complex (3) have been carried out. Electron density distribution (EDD) was determined through the use of high-resolution single crystal X-ray diffraction and the data were modelled using the conventional multipole model of electron density according to the Hansen-Coppens formalism. A method for optimising the core density refinement of sulfur atoms is discussed, with emphasis on the reduction of residual electron density that is typically associated with this atom. The asymmetric unit of complex (3) contains single molecules of saccharin and the zwitterionic form of piroxicam. These are held together by weak interactions (hydrogen bonds, π-π and van der Waals interactions), ranging in strength from 4 to 160 kJmol -1 , working together to stabilise the complex;. analysis of the molecular electrostatic potential (MEP) of the complexes showed electron redistribution within the cocrystal, facilitating the formation of these generally weak interactions. Interestingly, in the zwitterionic form of piroxicam, the charge distribution reveals that the positive and negative charges are not associated with the formal charges normally associated with this description, but are distributed over adjacent molecular fragments. The use of anisotropic displacement parameters (ADPs) for hydrogen atoms in the multipole model was also investigated but no improvement in the quality of the topological analysis was found.3

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“…21,22 In the solid state, P.Y. [24][25][26][27][28] Lorenz et al investigated the ultrafast photoinduced dynamics of P.Y. 22 Particularly, since its bright yellow color and high photostability, it is usually used as one kind of commercial colorant.…”

Section: Introductionmentioning

confidence: 99%

“…23 Even though P.Y. 28 Whereas the Scheme 1 of ref. [24][25][26][27][28] Lorenz et al investigated the ultrafast photoinduced dynamics of P.Y.…”

Section: Introductionmentioning

confidence: 99%

Detailed theoretical investigation on ESIPT process of pigment yellow 101

Zhang

Zhou

et al. 2016

RSC Adv.

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Based on density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods, the detailed excited state intramolecular proton transfer (ESIPT) mechanism of 2,2 0 -dihydroxy-1,1 0naphthalazine (P.Y. 101) has been investigated theoretically. Unlike previous theoretical investigation of P.Y. 101, our calculated results not only reproduce the absorption and fluorescence spectra reported in the previous experiment, but also were completed with considering solvent effect. It further demonstrates that the TDDFT theory we adopted is very reasonable and effective. The calculations of main bond lengths and bond angles involving in the hydrogen bondings (O 1 -H 2 /N 3 and O 4 -H 5 /N 6 ) as well as the infrared vibrational spectra and as well as the calculated hydrogen bonding energies demonstrated the intramolecular hydrogen bond was strengthened in the S 1 state. In addition, qualitative and quantitative intramolecular charge transfer based on the frontier molecular orbitals provided the possibility of the ESIPT reaction. The potential energy surfaces of ground state and the first excited state have been constructed to illustrate the ESIPT mechanism. Based on our calculations, the equilibrium ESIPT process exists in the S 1 state. And after the radiative transition, reversed GSIPT can also occur in the S 0 state.

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Experimental and theoretical charge density distribution in Pigment Yellow 101

Cited by 12 publications

References 29 publications

A comparison of the experimental and theoretical charge density distributions in two polymorphic modifications of piroxicam

A comparison of the experimental and theoretical charge density distributions in two polymorphic modifications of piroxicam

An analysis of the experimental and theoretical charge density distributions of the piroxicam–saccharin co-crystal and its constituents

Detailed theoretical investigation on ESIPT process of pigment yellow 101

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