Mutual atomic effect in porphyrin molecules and its manifestation in their structure and electronic absorption spectra

Berezin, B. D.

doi:10.1007/bf02675379

Cited by 5 publications

(4 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The possibility of n −π* transitions are not considered likely because of the symmetry of the n orbitals and because of the antisymmetry of the π* orbitals relative to the plane of the porphyrin macrocycle . A more extensive discussion on the effect of peripheral substituents on the electronic absorption of the porphyrin macrocycle using the so-called “Mutual Atomic Effect” was presented by Berezin . At this point, it is concluded that differences in peripheral substitution of the porphyrin macrocycle will have an impact on both the location and magnitude of electronic absorption peaks and must be accounted for when applying UV/visible spectroscopy for quantitation.…”

Section: To Be or Not To Be (A Porphyrin)that Is The Question The Ch...mentioning

confidence: 99%

Chemistry and Association of Vanadium Compounds in Heavy Oil and Bitumen, and Implications for Their Selective Removal

2010

View full text Add to dashboard Cite

Most crude oils contain traces of vanadium, which cause significant detrimental impact during catalytic conversion and combustion. The concentrations in bitumen and vacuum residue are generally much higher, which poses a problem for the economical upgrading of these feedstocks. These problems are relevant since the world reserves of conventional light oils are dwindling and being replaced by an increasing amount of heavier feedstocks. In this article, the current understanding of the distribution and form of vanadium compounds within vacuum residue is critically discussed. The implications of this chemistry on prospects for new separation methods, other than deasphalting, are considered. Although only a small fraction of the vanadium is contained within the polar resin fraction (i.e., maltenes), this fraction has been most often characterized to determine the chemical form of the vanadium compounds. Various spectroscopic techniques have been used to determine that these resin soluble vanadium compounds exist as metalloporphyrins characterized by their intense absorption of UV/visible radiation. In the case of the asphaltene bound metals, this UV/visible absorbance is not observed and has historically led to their distinction as “non-porphyrins”. However, more recent results using X-ray spectroscopies (EXAFS and XANES), as well as a more in depth analysis of the UV/vis response of metalloporphyrins, indicates that, although these asphaltene-bound vanadium compounds do not exhibit the characteristic UV/visible absorption, they are indeed still bound in a porphyrinic structure. The fact that the majority of the vanadium is contained within the highly aromatic, highly polar asphaltene fraction also poses additional roadblocks to their selective removal. This fraction has been shown to associate/aggregate significantly in most (if not all) solvents. Recent work on the nature and possible mechanisms of the molecular association of asphaltenes in solution can be extended to help elucidate the molecular interactions occurring between asphaltenes and metalloporphyrins, and hence the nature of the inclusion of metalloporphyrins within the asphaltene fraction. Many different solvent systems including aromatics, chloro-carbons, alcohols, ketones, as well as other polar solvents have been used to extract the metalloporphyrins from the asphaltene fraction with limited success. In most cases, the effect of asphaltene solubility and aggregation in the given solvent were not considered. The selective separation of metalloporphyrins is clearly hampered by gaps in the basic understanding of the metalloporphyrin properties and behavior in solution.

show abstract

Section: To Be or Not To Be (A Porphyrin)that Is The Question The Ch...mentioning

confidence: 99%

Chemistry and Association of Vanadium Compounds in Heavy Oil and Bitumen, and Implications for Their Selective Removal

2010

View full text Add to dashboard Cite

show abstract

“…2. This phenomenon instigates a spectral shift and/or higher/ lower extinction coefficient [23]. The dissimilarity in the Soret-, α-or β-band of each vanadyl-porphyrin caused [24][25] also reported on the variations in extinction coefficients amongst one another.…”

Section: ■ Structure Of Metallic Porphyrinsmentioning

confidence: 97%

“…3 shows some examples of metallic porphyrin structures discovered, while Table 2 demonstrate the Soret-, α-, and β-bands of specific vanadyl forms. Berezin [23] introduced the concept of "Mutual Atomic Effect", which describes the influence of different peripheral substitution on the electronic distribution and light absorption magnitude, as observed in Fig. 2.…”

Section: ■ Structure Of Metallic Porphyrinsmentioning

confidence: 99%

The Origin, Physicochemical Properties, and Removal Technology of Metallic Porphyrins from Crude Oils

et al. 2021

View full text Add to dashboard Cite

Crude oil is an indispensable energy feedstock for daily activities, although some amounts of metallic porphyrins components with undesired characteristics have been identified. These constituents are assumed to originate from the geochemical process of chlorophyll and heme derivatives. In addition, their chemical structures have been thoroughly characterized using spectroscopy techniques, while several analytical methods were adopted in the detection and concentration quantification in the crude oils. The metallic porphyrins have several demerits, including the deactivation of used catalysts, contamination of the treated petrochemical products, and corrosion of the industrial equipment. Also, the removal process is considered challenging due to the strong interaction with the asphaltene fraction of crude oil. This review article, therefore, provides brief information on the origin, physicochemical properties, and possible removal technology of metallic porphyrins from crude oil samples. Besides, a better understanding of chemistry contributes a useful insight towards the development and establishment of better futuristic processing technology.

show abstract

“…It should be noted that for the calculation we used only the well-defined peaks while the shoulders were ignored. According to the spectral criteria of stability Δλ I in cyclohexane, benzene, and chloroform (the solvents which are not able to solvate a complex-forming atom specifically [13] [12,14] An exception is [AgP] complex, which is less stable then [AgТРP] probably due to the reducing of inverse dative π-effect of Ag →  π N coordination owing to the strong +I-induction effect of substituents.…”

Section: Solvation Of Tetrakis(35-di-tert-butylphenyl)porphinesmentioning

confidence: 99%

Spectral Characteristics and Solvation of Tetrakis(3,5-di-tert-butylphenyl)porphine and its Complexes with Some d Metals

Антина¹,

Balantseva²,

Berezin³

2010

MHC

View full text Add to dashboard Cite

show abstract

Mutual atomic effect in porphyrin molecules and its manifestation in their structure and electronic absorption spectra

Cited by 5 publications

References 2 publications

Chemistry and Association of Vanadium Compounds in Heavy Oil and Bitumen, and Implications for Their Selective Removal

Chemistry and Association of Vanadium Compounds in Heavy Oil and Bitumen, and Implications for Their Selective Removal

The Origin, Physicochemical Properties, and Removal Technology of Metallic Porphyrins from Crude Oils

Spectral Characteristics and Solvation of Tetrakis(3,5-di-tert-butylphenyl)porphine and its Complexes with Some d Metals

Contact Info

Product

Resources

About