Structures and spectroscopic properties of nonperipherally and peripherally substituted metal-free phthalocyanines: A substitution effect study based on density functional theory calculations

2010 ◽  
Vol 29 (3) ◽  
pp. 470-480 ◽  
Author(s):  
Aimin Zhong ◽  
Yuexing Zhang ◽  
Yongzhong Bian
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Substitution Effect ◽  
Spectroscopic Properties ◽  
Effect Study ◽  
Functional Theory ◽  
Metal Free

scholarly journals Towards hydrophobic carminic acid derivatives and their incorporation in polyacrylates

2018 ◽  
Vol 5 (7) ◽  
pp. 172399 ◽  
Author(s):  
Luca Gabrielli ◽  
Davide Origgi ◽  
Giuseppe Zampella ◽  
Luca Bertini ◽  
Simone Bonetti ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Dimethyl Sulfoxide ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Spectroscopic Properties ◽  
Carminic Acid ◽  
Functional Theory ◽  
Time Resolved ◽  
Sugar Ring ◽  
Time Resolved Photoluminescence

Carminic acid, a natural hydrophilic dye extensively used in the food and cosmetic industries, is converted in hydrophobic dyes by acetylation or pivaloylation. These derivatives are successfully used as biocolourants for rubber objects. In this paper, spectroscopic properties of the carminic acid derivatives in dimethyl sulfoxide and in polybutylacrylate are studied by means of photoluminescence and time-resolved photoluminescence decays, revealing a hypsochromic effect due to the presence of bulky substituents as the acetyl or pivaloyl groups. Molecular mechanics and density functional theory calculations confirm the disruption of planarity between the sugar ring and the anthraquinoid system determined by the esterification.

scholarly journals Chemoselective catalytic hydrodefluorination of trifluoromethylalkenes towards mono-/gem-di-fluoroalkenes under metal-free conditions

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jingjing Zhang ◽  
Jin-Dong Yang ◽  
Jin-Pei Cheng
Keyword(s):  
Density Functional Theory ◽  
Fluorine Atom ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Reaction Conditions ◽  
Functional Theory ◽  
Stepwise Mechanism ◽  
Metal Free ◽  
Great Demand ◽  
Good Group

AbstractFluorine-containing moieties show significant effects in improving the properties of functional molecules. Consequently, efficient methods for installing them into target compounds are in great demand, especially those enabled by metal-free catalysis. Here we show a diazaphospholene-catalyzed hydrodefluorination of trifluoromethylalkenes to chemoselectively construct gem-difluoroalkenes and terminal monofluoroalkenes by simple adjustment of the reactant stoichiometry. This metal-free hydrodefluorination features mild reaction conditions, good group compatibility, and almost quantitative yields for both product types. Stoichiometric experiments indicated a stepwise mechanism: hydridic addition to fluoroalkenes and subsequent β-F elimination from hydrophosphination intermediates. Density functional theory calculations disclosed the origin of chemoselectivity, regioselectivity and stereoselectivity, suggesting an electron-donating effect of the alkene-terminal fluorine atom.

scholarly journals Predicting the paramagnet-enhanced NMR relaxation of H 2 encapsulated in endofullerene nitroxides by density-functional theory calculations

2013 ◽  
Vol 371 (1998) ◽  
pp. 20110634 ◽  
Author(s):  
Federico Rastrelli ◽  
Diego Frezzato ◽  
Ronald G. Lawler ◽  
Yongjun Li ◽  
Nicholas J. Turro ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Diffusion Tensor ◽  
Nmr Relaxation ◽  
Density Functional Theory Calculations ◽  
Spectroscopic Properties ◽  
Rotational Correlation Time ◽  
Conformational Space ◽  
Geometrical Parameters ◽  
Functional Theory

We have investigated the structure and nuclear magnetic resonance (NMR) spectroscopic properties of some dihydrogen endofullerene nitroxides by means of density-functional theory (DFT) calculations. Quantum versus classical roto-translational dynamics of H 2 have been characterized and compared. Geometrical parameters and hyperfine couplings calculated by DFT have been input to the Solomon–Bloembergen equations to predict the enhancement of the NMR longitudinal relaxation of H 2 due to coupling with the unpaired electron. Estimating the rotational correlation time via computed molecular volumes leads to a fair agreement with experiment for the simplest derivative; the estimate is considerably improved by recourse to the calculation of the diffusion tensor. For the other more flexible congeners, the agreement is less good, which may be due to an insufficient sampling of the conformational space. In all cases, relaxation by Fermi contact and Curie mechanisms is predicted to be negligible.

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