Synthesis of o- and m-Carborane-substituted Porphyrins of the Natural Type

Basing on protoporphyrin IX, its monobenzyl ester, deuteroporphyrin IX, 9-hydroxymethyl-m- and 9-hydroxymethyl-p-carboranes, mono- and dicarborane-containing porphyrins were prepared.     

Photophysical properties of carborane-containing derivatives of 5,10,15,20-tetra(p-aminophenyl)porphyrin

Absorption, fluorescence emission, fluorescence excitation spectra and fluorescence decay kinetics of carborane derivatives of 5,10,15,20-tetra(p-aminophenyl)porphyrin have been investigated. Carborane derivatives are prepared by acylation of the amino groups of 5,10,15,20-tetra(p-aminophenyl)porphyrin by 9-carboranyl acetyl chloride. From the analysis of the absorption and fluorescence spectra, it is concluded that covalent linking of carborane molecules to the tetraphenylporphyrin molecule significantly changes the self-conjugated pi-system of the porphyrin macrocycle: positions of maxima of absorption and fluorescence spectra shift to the red region by 3-8 nm; the halfwidths of these bands are broadened by 2.5-5.0 nm; the relative intensity of the bands I-IV also changes. The fluorescence decay kinetics of the carborane derivatives are biexponential. According to the experimental data and model simulation, it is concluded that the intramolecular electron transfer proceeds from the porphyrin excited part of the molecule to carboranyls with a rate constant of 415 ps(-1) and efficiency of 0.16-0.8. Recombination of separated charges occurs within 1.4 ns.     

Synthesis of boron-containing derivatives of pyropheophorbide <Emphasis Type="ItalicUnderline">a</Emphasis> and investigation of their photophysical and biological properties

Proceeding from pyropheophorbide a and 9-hydroxymethyl-m-carborane, 1-hydroxymethyl-o-carborane, and 3-amino-o-carborane new carboranylchlorins were prepared, and their photophysical and biological properties were investigated.     

Synthesis of carboranyl derivatives of deuteroporphyrin IX

Carboranylporphyrins, which can be used in boron neutron-choture therapy of cancer, were prepared from natural deuteroporphyrin IX, 3-amino-o-carborate, and 9-hydroxymethyl-m-carborane. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2337–2339 December, 1999.     

Synthesis of 5,10,15,20-tetra[3-(o- andm-carboranyl)butyl]porphyrins containing the C−B σ-bond

5,10,15,20-Tetra[3-(o- andm-carboranyl)butyl]porphyrins containing carborane groups bonded to alkyl substituents of the porphyrin cycle by the C−B σ-bond were obtained by condensation of 4-(o- andm-carboran-9-yl)pentanals with pyrrole. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 347–349, February, 1998.     

Porphyrin photosensitizers solubilized with pluronics in the oxidation of tryptophan

It was shown that water-insoluble porphyrins solubilized with pluronics (ternary block copolymers of ethylene oxide and propylene oxide) efficiently transfer photoexcitation energy to molecular oxygen dissolved in aqueous media to excite it into the singlet state, which is active in oxidizing organic substrates. It was established that the degree of solubilization of porphyrin photosensitizers (PPSs) γ defined as the proportion of PPS molecules passed into the aqueous phase in the dissolution of formed films depends on a single parameter, the initial ratio between the porphyrin and pluronic molar concentrations q. γ = γ(q) dependences for the solubilization of dissimilar water-insoluble porphyrins were analyzed. It was shown that the behavior of all the obtained γ = γ(q) dependences is changed at a characteristic value q _max: when q ? q _max, γ ～ 1, and, when q ≥ ?q_max, the degree of solubilization decreases. It was concluded that solubilized porphyrins are efficient photosensitizers in the oxidation of organic substrates (tryptophan).     

Quantifying uncertainty in the measurement of arsenic in suspended particulate matter by Atomic Absorption Spectrometry with hydride generator

Arsenic is the toxic element, which creates several problems in human being specially when inhaled through air. So the accurate and precise measurement of arsenic in suspended particulate matter (SPM) is of prime importance as it gives information about the level of toxicity in the environment, and preventive measures could be taken in the effective areas. Quality assurance is equally important in the measurement of arsenic in SPM samples before making any decision. The quality and reliability of the data of such volatile elements depends upon the measurement of uncertainty of each step involved from sampling to analysis. The analytical results quantifying uncertainty gives a measure of the confidence level of the concerned laboratory. So the main objective of this study was to determine arsenic content in SPM samples with uncertainty budget and to find out various potential sources of uncertainty, which affects the results. Keeping these facts, we have selected seven diverse sites of Delhi (National Capital of India) for quantification of arsenic content in SPM samples with uncertainty budget following sampling by HVS to analysis by Atomic Absorption Spectrometer-Hydride Generator (AAS-HG). In the measurement of arsenic in SPM samples so many steps are involved from sampling to final result and we have considered various potential sources of uncertainties. The calculation of uncertainty is based on ISO/IEC17025: 2005 document and EURACHEM guideline. It has been found that the final results mostly depend on the uncertainty in measurement mainly due to repeatability, final volume prepared for analysis, weighing balance and sampling by HVS. After the analysis of data of seven diverse sites of Delhi, it has been concluded that during the period from 31^st Jan. 2008 to 7^th Feb. 2008 the arsenic concentration varies from 1.44 ± 0.25 to 5.58 ± 0.55 ng/m³ with 95% confidence level (k = 2).