Single-Step and Multistep Mechanisms of Aromatic Nucleophilic Substitution of Halobenzenes and Halonitrobenzenes with Halide Anions:  Ab Initio Computational Study

1997 ◽  
Vol 62 (12) ◽  
pp. 4036-4046 ◽  
Author(s):  
Mikhail N. Glukhovtsev ◽  
Robert D. Bach ◽  
Sergei Laiter
Keyword(s):  
Ab Initio ◽  
Nucleophilic Substitution ◽  
Computational Study ◽  
Single Step ◽  
Aromatic Nucleophilic Substitution ◽  
Halide Anions

Photodynamic activity of new photosensitizers obtained from 5,10,15,20-tetrapentafluorophenylporphyrin

2019 ◽  
Vol 23 (09) ◽  
pp. 1047-1056 ◽  
Author(s):  
Miryam C. Malacarne ◽  
Stefano Banfi ◽  
Anna S. Alberton ◽  
Enrico Caruso
Keyword(s):  
Nucleophilic Substitution ◽  
Cellular Uptake ◽  
Cancer Cell Line ◽  
Single Step ◽  
Hydroxyl Groups ◽  
Aromatic Nucleophilic Substitution ◽  
Killing Effect ◽  
Polar Groups ◽  
Photodynamic Activity ◽  
Pure Compounds

The commercially available tetrapentafluorophenylporphyrin has been used as parent compounds for the synthesis of six new tetraarylporphyrins. These new porphyrins were obtained following aromatic nucleophilic substitution of the para-position fluorine atoms by means of molecules bearing an oxygen or sulphur anion, providing either tri- or tetra-substituted derivatives which were isolated as pure compounds after a single step of column chromatography purification. These new porphyrins, first analyzed to determine the photobleaching stability and the octanol/water repartition values, were studied as photosensitizers against the HCT116 cancer cell line with irradiation by a blue LED device. The intrinsic toxicity of these compounds was negligible, whereas the photodynamic efficacy was found to be directly related to the cellular uptake of the photosensitizer that was correlated with the hydrophilicity of the substituent. In fact, the PSs lacking of any polar groups were found to be poorly efficient while the photosensitizer bearing four hydroxyl groups showed the greatest photodynamic activity, thus confirming the importance of the presence of polar appendixes to properly interact with the cells, thus exerting the desired photo-killing effect.

Computational Study on the Kinetics and Mechanisms of Unimolecular Reactions of (Z)-(Z)-N-(λ5-phosphanylidene) Formohydrazonic Formic Anhydride: Intramolecular aza-Wittig Reaction in Competition with Mumm Rearrangement

2020 ◽  
Vol 17 (11) ◽  
pp. 884-889
Author(s):  
Somayeh Mirdoraghi ◽  
Hamed Douroudgari ◽  
Farideh Piri ◽  
Morteza Vahedpour
Keyword(s):  
Rate Constants ◽  
Density Functional ◽  
Wittig Reaction ◽  
Computational Study ◽  
Single Step ◽  
Low Energy ◽  
Coupled Cluster ◽  
Unimolecular Reaction ◽  
Single Step Reaction ◽  
Good Agreement

For (Z)-(Z)-N-(λ5-phosphanylidene) formohydrazonic formic anhydride, Aza-Wittig reaction and Mumm rearrangement are studied using both density functional and coupled cluster theories. For this purpose, two different products starting from one substrate are considered that are competing with each other. The obtained products, P1 and P2, are thermodynamically favorable. The product of the aza-Wittig reaction, P1, is more stable than the product of Mumm rearrangement (P2). For the mentioned products, just one reliable pathway is separately proposed based on unimolecular reaction. Therefore, the rate constants based on RRKM theory in 300-600 K temperature range are calculated. Results show that the P1 generation pathway is a suitable path due to low energy barriers than the path P2. The first path has three steps with three transition states, TS1, TS2, and TS3. The P2 production path is a single-step reaction. In CCSD level, the computed barrier energies are 14.55, 2.196, and 10.67 kcal/mol for Aza-Wittig reaction and 42.41 kcal/mol for Mumm rearrangement in comparison with the corresponding complexes or reactants. For final products, the results of the computational study are in a good agreement with experimental predictions.

scholarly journals Density Functional Theory and Complete Basis Set Ab Initio Computational Study of Five-, Six-, Seven- and Eight-hydrogen Coordinated Carbon Cations

1999 ◽  
Vol 23 (8) ◽  
pp. 502-503
Author(s):  
Branko S. Jursic
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Computational Study ◽  
Basis Set ◽  
Functional Theory ◽  
Complete Basis ◽  
Complete Basis Set ◽  
High Level

High level ab initio and density functional theory studies are performed on highly protonated methane species.

Sign in / Sign up

Export Citation Format

Share Document