1516-60-5Relevant articles and documents
Investigating the Impact of Conformational Molecular Engineering on the Crystal Packing of Cavity Forming Porphyrins
Flanagan, Keith J.,Twamley, Brendan,Senge, Mathias O.
, p. 15769 - 15787 (2019)
Herein we report the synthesis of 5,10,15,20-tetraaryl-(X)-substituted-2,3,7,8,12,13,17,18-octaethylporphyrins (OETArXPs) and a structural investigation of their solid-state properties via small molecule X-ray diffraction. A series of halogen (fluorine to iodine), nitrogenous (azido, cyano), alkyl (TMS-acetylene and acetylene), and chained (benzyloxy) porphyrins were chosen as the initial target molecules. Following this, a selection of tetravalent metal complexes [Cu(II), Ni(II), and Pd(II)] based on these porphyrins were synthesized to allow for an investigation of the effects of metal complexes on the structural properties of these highly substituted porphyrins. The size of the halogen atom affects the potential of intermolecular interactions and the resulting crystal packing in these 4-halo-OETArXP complexes. The fluorine series have an equal preference for alkyl or aryl groups (ortho-hydrogen), the chlorine series favor interactions between the alkyl groups, and the bromine appears to favor the aryl (ortho- and meta-hydrogens). This results in an extensive cupping pattern in the unit cell. For the 2,6-halo-OETArXP it was established that the change in position alters the types of the intermolecular contacts toward face-to-edge or face-to-face interactions and alters the packing patterns observed. Within the 4-benzyloxy-OETArXP series the meso-substituent favors interacting with the core of the porphyrin macrocycle. The 4-cyano-OETArXP is a suitable hydrogen-bond acceptor and results in an interesting Z-shape network. Additionally, it was highlighted that solvent effects play a much larger role in crystal packing than intermolecular/intramolecular interaction or metal(II) center substitution. This is accompanied by a study using both the azide- and acetylene-OETArXPs as a base molecule to allow for a quick one-step reaction for the generation of a variety of functionalized compounds. Using a copper(I)-catalyzed azide-alkyne cycloaddition reaction, we were able to append hydrogen bonding functionalities to the OETArXPs framework in high yields. The crystal packing images included in this work shows the potential to create selective and functional receptor sites based on free base porphyrins. However, insofar as analytical measurements indicate, the design of such a free base porphyrin through crystal engineering has not yet been realized. The variety of porphyrin packing arrangements herein indicates the need for further studies.
Synthesis of nitrophenyl and fluorophenyl azides and diazides by SNAr under phase-transfer or microwave irradiation: Fast and mild methodologies to prepare photoaffinity labeling, crosslinking, and click chemistry reagents
Leyva, Elisa,Aguilar, Johana,González-Balderas, Regina M.,Vega-Rodríguez, Sarai,Loredo-Carrillo, Silvia E.
, (2020/12/01)
Two fast and mild methodologies to prepare nitrophenyl and fluorophenyl azides are presented. These aryl azides are extensively used as crosslinking, photoaffinity labeling, and click chemistry reagents. Substituted aryl azides are prepared by performing a SNAr substitution on halogenated benzenes with a phase-transfer catalyst (PTC) such as tetraethylammonium tetrafluoroborate (TEATFB), the reaction proceeds in several hours under rather mild temperatures (25°C to 70°C). Furthermore, aryl azides are also prepared within minutes under microwave irradiation at slightly higher temperatures (50°C to 70°C). These procedures could be applied in the preparation of other aryl azides. In the case of substituted pentafluoro benzene (pF), the type of products obtained in each reaction depends on the amount of sodium azide and the strength and position of electron-withdrawing substituents (COH, COR, COOR, CN, NO2, or F). A discussion on the mechanisms and the products obtained in these SNAr reactions is presented.
Two-Phase Electrochemical Generation of Aryldiazonium Salts: Application in Electrogenerated Copper-Catalyzed Sandmeyer Reactions
Goljani, Hamed,Tavakkoli, Zahra,Sadatnabi, Ali,Nematollahi, Davood
supporting information, p. 5920 - 5924 (2020/08/12)
The electrochemical generation of aryldiazonium salts from nitroarenes in a two-phase system (ethyl acetate/water) was reported for the first time. Some compounds including azo, azosulfone, and arylazides were prepared in good yields with good purity. Cathodically generated aryldiazoniums and anodically produced copper(Ι) ions were used to perform Sandmeyer reactions. To improve the method, an H-type self-driving cell equipped with a Zn rod as an anode was introduced and used for two-phase aryldiazonium production.
