Porphyrin

About: Porphyrin is a research topic. Over the lifetime, 22226 publications have been published within this topic receiving 510695 citations. The topic is also known as: porphyrin.

Reactivity of tetraazaporphyrins in the acid-base interactions with nitrogen bases

Abstract: The review analyzes the data on the reactivity of β-substituted and β, β-tetrabenzofused tetraaza porphyrins in acid-base interactions in benzene and dimethylsulfoxide with cyclic and acyclic, in the latter case primary, secondary, and tertiary, nitrogen bases. Unusually low rate of the processes was established. The effect of the medium dielectric permittivity, the nature of the base and of the substituents in the tetraaza porphyrin macrocycle on the rate and activation parameters of acid-base interactions are demonstrated. The structure and stability of the tetraaza porphyrin complexes with the proton transfer are discussed.

New luminescent fluorenyl-armed linear porphyrin trimers with diphenylacetylene bridges

Abstract: First a series of porphyrins bearing various fluorenyl donor groups is presented; an intermediate porphyrin bearing three fluorenyl arms (zinc complex 12 ) and compound 13 , bearing only two fluorenyl groups. Then starting from these building blocks, synthesis of new porphyrin trimers 7 and 8 , with in totally eight peripheral fluorenyl arms is performed by using a palladium catalyst. Photophysical properties; absorption and luminescence, of new trimers 7 and 8 are presented. We can then compare these properties to those of reference porphyrin monomer TFP ( 2 ), as well as to those of porphyrin dendrimers bearing various numbers of fluorenyl arms ( 3 and 4 ) and finally to those of the corresponding dimers 5 and 6 , which are the precursor models of this work.

Ultrafast Guanine Oxidation by Photoexcited Cationic Porphyrins Intercalated into DNA

Abstract: The photophysical and photochemical properties of a cationic porphyrin [bis(arginyl)porphyrin (BAP)] complexed to [poly(dG-dC)] 2 and [poly(dA-dT)] 2 have been investigated and compared to those of free BAP in aqueous solution. A drastic enhancement of the quantum yield of nonradiative deactivation of the lowest excited singlet state of BAP is observed upon intercalation between GC base pairs in [poly(dG-dC)] 2 but not upon complexation with [poly(dA-dT)] 2 . Both picosecond time-resolved fluorescence and femtosecond transient absorption measurements give evidence for the occurrence of an ultrafast direct electron transfer (k ≥ 1.25 × 10 1 3 s - 1 ) from guanine to the lowest excited singlet state of BAP followed by an efficient back electron transfer (k = 8.3 x 10 1 2 s - 1 ). A classical nonadiabatic Marcus model for this reverse electron transfer explains the experimental observations which allow one to estimate the electronic coupling energy (230 cm - 1 ) involved for BAP-[poly(dG-dC)] 2 complexes.

Bilayer structured supramolecular light harvesting arrays based on zinc porphyrin coordination polymers for enhanced photocurrent generation in dye sensitized solar cells

Abstract: An acylhydrazone zinc porphyrin P1 and its coordination polymers (CPs, denoted as P1M, M = Mn, Co, Ni, Cu, Zn) with different metal ions (Mn2+, Co2+, Ni2+, Cu2+ and Zn2+) were synthesized. Then these coordination polymers were assembled into bilayer structured supramolecular chromophores through axially coordinating with anchoring porphyrin AP, and their performance in dye sensitized solar cells was investigated. Our results reveal that the bilayer structured supramolecular chromophore based solar cells show significantly improved photocurrent conversion efficiency. Particularly, P1Mn and P1Zn based solar cells showed a relatively higher short circuit current density (JSC) due to their broad absorption bands and remarkable light harvesting abilities. Meanwhile, the VOC values of the cells fabricated with the bilayered chromophores slightly decreased. Electrochemical impedance spectroscopy (EIS) in combination with charge extraction (CE) and transient photovoltage decay (TPD) measurements indicates that the decreased VOC resulted from the vigorous electron recombination and the downward shifted conduction band edge (ECB) of titania.