Abstract
Competition studies of the free base octa alkyl substituted porphyrins for the protons were carried out using H2TPP. The reaction with H2OEP produces the free base H2OEP, the dication H4OEP+2, and the monocation H3OEP+1. Although the monocation is easily seen in the solution, it is difficult to isolate. The cause appears to be a type of disproportionation reaction taking place upon crystallization, where the dication is formed at the expense of the monocation. In each experiment, an equimolar solution of two free-bases was made. Since H2TPP has a large absorption for the dication at 650 nm, it was always used as one of the free-bases. By adjusting the ratios of dications and free-bases, we concluded that H2TPP was again preferentially protonated and hence more basic than the octa alkyl substituted porphyrins (H2OEP, H2OMP H2etiol). Computations studies using MM+ and semiempirical methods were used to validate the porphyrin basicity.
Faculty Sponsors
Dr. Maria Ballester
Project Type
Event
Location
Alvin Sherman Library
Start Date
4-8-2016 1:00 PM
End Date
4-8-2016 5:30 PM
Porphyrin Basicity Competition Studies of Octa Alkyl Substituted Porphyrins with H2TPP
Alvin Sherman Library
Competition studies of the free base octa alkyl substituted porphyrins for the protons were carried out using H2TPP. The reaction with H2OEP produces the free base H2OEP, the dication H4OEP+2, and the monocation H3OEP+1. Although the monocation is easily seen in the solution, it is difficult to isolate. The cause appears to be a type of disproportionation reaction taking place upon crystallization, where the dication is formed at the expense of the monocation. In each experiment, an equimolar solution of two free-bases was made. Since H2TPP has a large absorption for the dication at 650 nm, it was always used as one of the free-bases. By adjusting the ratios of dications and free-bases, we concluded that H2TPP was again preferentially protonated and hence more basic than the octa alkyl substituted porphyrins (H2OEP, H2OMP H2etiol). Computations studies using MM+ and semiempirical methods were used to validate the porphyrin basicity.
