Probing the Interactions of Porphyrins with Macromolecules Using NMR Spectroscopy Techniques (original) (raw)
Related papers
Georgia journal of science : official publication of the Georgia Academy of Science, 2011
Porphyrins are a group of tetrapyrrole pigments. Physical and chemical properties of porphyrins are often related to their compositions and structures. We conducted (1)H solution NMR and UV-visible spectral analysis to characterize the structural feature of a water-soluble, synthetic porphyrin i.e. tetrakis (p-sulfonatophenyl) porphyrin, TPPS4, and its interaction with different metal ions in aqueous solutions. The results indicate that tetrapyrrole and tetraphenyl rings in TPPS4 molecule form a co-planar electron conjugation system; transition-metal ions show stronger binding capacity than alkali and alkali-earth metal ions; the relative stabilities of TPPS4-metal ion complexes can be well assessed by NMR and UV-visible spectral data.
ChemInform, 2011
Analysis of the relationship between the molecular structure of porphyrins and the spectral features of their monoand diprotonated forms in solution is presented. The evolution of the concept of the role of acid-base equilibria in the formation of the spectral properties and the excitation energy deactivation pathways in porphyrins are reviewed. The trends observed in the fluorescence and intersystem crossing quantum yields on going from free base porphyrins to their mono-and diprotonated forms are analyzed, and the mechanisms involved are discussed.
Semiempirical and spectroscopic study of a novel porphyrin dyad
International Journal of Quantum Chemistry, 2001
Semiempirical calculations and ultraviolet-visible experiments have been carried out on a novel bisporphyrin system. The present work reveals that an oligothiophene ethynyl-linked spacer promotes high electronic interactions over a large distance in this dyad.
Journal of Fluorescence, 2020
New porphyrin analogues have been designed and synthesized using pyrrole, various aldehydes and propionic acid. The formation of desired compounds was analyzed by utilizing the spectral analysis such as IR, NMR and Mass spectroscopy. The studies on absorption and fluorescence emission of synthesized porphyrins were used to evaluate photophysical characteristics such as molar excitation coefficient and Stokes shift. The estimated values of fluorescence lifetime and fluorescence quantum yield of synthesized porphyrins were found to be variable due to the presence of change in the electron donating and withdrawing characters. The efficiency of generation of singlet oxygen by each synthesized porphyrin as photosensitizer was measured in terms of singlet oxygen quantum yield through photooxidation of 9,10-dimethylantharacene. The obtained singlet oxygen quantum yield values were found to be higher in case of porphyrins those have more electron withdrawing characters rather than donating characters as compared to reference 5,10,15,20-tetraphenylporphyrin (H 2 TPP). The singlet oxygen quantum yield values of synthesized porphyrins varied from 0.52 to 0.66. Pleasingly, some of synthesized porphyrins are found to be photostable and competent to discover as PDT agents as compared to reference H 2 TPP.
Computational and Theoretical Chemistry, 2018
The nature of the solvent and composition of the solution in which optical absorption spectra are acquired can substantially affect the structures of analytes as well as spectra and relative intensities of spectral features. We have computed the effects of the solvent for dilute solutions on the electronic absorption spectra and structures of a prototypical porphyrin-free-base porphyrin (herein referred to as FBP and H 2 FBP)-and its protonated form (H 4 FBP) in the ground and the lowest triplet states, both important in device and medical applications. Density functional theory (DFT) and time-dependent-DFT (TD-DFT) have been employed to investigate solvent effects on structure and singlet-singlet (S 0 S n) and triplettriplet (T 1 T n) absorption spectra. We also calculated the solvent dependence of energy gaps between optically allowed singlet and nearest triplet states for the species. Soret band positions are found to be strongly solvent dependent, but less so are Q bands. The finding of dependence of the spectroscopic features of the porphyrin on the dielectric constant of the solvent, from 1.00 (gas-phase) to about 20.493 (acetone)-with the features becoming stable for polar solvents with the dielectric constants ε 20-can be used to monitor micro environmental changes of porphyrin (and its derivatives) embedded in biological systems and nanoparticles; such composites may also be suitable to study and monitor modifications of the chemical environment in different solutions and interactions with biological systems and nanoparticles. This is first systematical study on the solvent-dependence of the porphyrin compounds.
Synthesis and spectral evaluation of 5,10,15,20-tetrakis(3,4-dibenzyloxyphenyl)porphyrin
Heterocyclic Communications, 2017
Porphyrins are of interest in many applications that involve electron transfer and absorption of light, such as solar energy and photodynamic cancer therapy. The newly synthesized 5,10,15,20-tetrakis(3,4-dibenzyloxyphenyl)porphyrin, TDBOPP, was characterized using 1H NMR, 13C NMR, UV-vis and fluorescence spectroscopy and MALDI-TOF/TOF high resolution mass spectrometry. Standard 1H NMR and 13C NMR experiments coupled with nuclear Overhauser effect (NOE) experiments confirmed the structure of the compound. The expected M+ and [M+H]+ ions are observed in the MALDI-TOF/TOF mass spectrum. The UV-vis absorption spectrum of TDBOPP shows a Soret band at 424 nm and three Q bands at 519 nm, 556 nm, and 650 nm with molar absorptivity 3.6×105 cm−1 m −1, 1.6×104 cm−1 m −1, 1.0×104 cm−1 m −1 and 5.3×103 cm−1 m −1, respectively. Excitation at 424 nm gives emission at 650 nm. The quantum yield of the porphyrin is 0.11.