Studies of opal crystals infiltrated with iron porphyrin

Sabataityte, J.; Šimkienė, I.; Rėza, A.; Babonas, G.-J.; Vaišnoras, R.; Rastenienė, Loreta; Kurdyukov, D. A.; Голубев, В. Г.

doi:10.1016/j.spmi.2008.01.017

Cited by 2 publications

(5 citation statements)

References 9 publications

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“…1). However, as follows from detailed analysis [6], the absorption Q-bands of FeTPPS were strongly influenced by ethanol due to the formation of chemical bonds between sulfonic groups of porphyrin with silanol groups on surface of silica spheres and with ethoxy groups in ethanol environment. As a result, the Q 1 (575 nm) and Q 0 (620 nm) bands were shifted towards longer wavelengths by ∼20 and ∼30 nm, respectively, in the opal samples immersed in ethanol.…”

Section: Resultsmentioning

confidence: 99%

“…The fine structure of the optical spectra of highconcentration FeTPPS buffered solutions have been described elsewhere [6]. The MCD spectra of highconcentration (10 mM) FeTPPS solutions ( Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In optical studies the FeTPPS-impregnated opal samples were immersed in polar (ethanol) or non-polar (hexane, toluene) solutions to vary the average refractive index of composite system and to control the mutual positions of the opal stop band and absorption bands of FeTPPS [6]. During multiple experimental runs, that included immersion and drying of composite samples, the optical spectra did not change significantly indicating that FeTPPS formations deposited on SiO 2 spheres were stable.…”

Section: Experimental Set-upmentioning

confidence: 99%

“…It was found that photonic band structure of synthetic opal could be controlled by external illumination due to infiltrated photochromic dye aggregates [4]. The stop band was continuously tuned by infiltrating mixed liquids into the voids in opal structure leading to the change of refraction index contrast of silica spheres and liquids [5,6].…”

Section: Introductionmentioning

confidence: 99%

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Magnetic circular dichroism of opal crystals infiltrated with iron porphyrin

Rėza¹

2008

Lithuanian J. Phys.

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Synthetic opal crystals composed of silica spheres of diameter ∼250 nm were infiltrated with highly concentrated (10 mM) buffered phosphate solution of iron porphyrin (FeTPPS). Magnetic circular dichroism (MCD) in the visible spectral range was investigated on hybrid samples immersed in polar (ethanol) or non-polar (hexane, toluene) solutions and situated in magnetic field. The MCD effect was observed in the spectral region of 550-650 nm in the vicinity of Q-absorption bands of FeTPPS. In 350 mT magnetic field the relative optical transmission change by 2.4·10 −4 was determined at the Q0-band of 0.3 mm thick infiltrated opal sample. The dispersion-like lineshape of MCD spectra corresponded to the A-type term. An average refraction index and refraction index contrast of composite system was controlled by immersion of infiltrated opal samples into various liquids. As a result, the spectral position of the stop band in opal photonic crystal was tuned with respect to FeTPPS absorption bands. When the Q band of FeTPPS was within the stop band of opal, the optical contrast of photonic crystal was changed by external magnetic field due to the MCD effect.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Experimental Set-upmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Magnetic circular dichroism of opal crystals infiltrated with iron porphyrin

Rėza¹

2008

Lithuanian J. Phys.

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“…Here we use infiltration of the opal pores with the Ashalchinskoe crude oil containing native vanadyl (VO) paramagnetic centers to probe the interaction with the silica surface with aim to shed light on details of adsorption of oil asphaltenes on silica. The effectiveness of the use of paramagnetic vanadyl complexes as spin probes is determined by the resolved anisotropic spectral parameters (g-factor, hyperfine splitiing, zero-field splitting, quadropole tensors) in the EPR/ENDOR spectra [16], the known affinity of porphyrin complexes and oil asphaltenes to silica surfaces [17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Probing the surface of synthetic opals with the vanadyl containing crude oil by using EPR and ENDOR techniques

Gafurov¹,

Galukhin²,

Osin³

et al. 2019

MRSej

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Porous silica materials offer wide range of possibilities for enhancement of the productivity of oil reservoirs. However the mechanism of adsorption of polar components of crude oil on silica surface is poorly understood that hinders technological improvement of supports and oil extraction. We have synthesized opal films with the silica microspheres size of about 360 ± 20 nm, specific surface area of 5.2 m 2 × g −1 and pore size of 230 nm. We have fractionated and characterized oil and oil asphaltenes from heavy (Ashalchinskoe) oil. By pulsed electron paramagnetic resonance (EPR) and double electron-nuclear resonance (ENDOR) in the W-band frequency range (microwave frequency of 94 GHz, magnetic field of 3.4 T) we have studied the adsorption of oil asphaltenes on the surface of opal samples using the intrinsic for asphaltenes paramagnetic vanadylporphyrins (VO) complexes. 1 H ENDOR spectra are found to be different for initial and the adsorbed samples in their central parts (that is a sign of asphaltenes VO disaggregation) whereas no significant changes in the W-band EPR spectra were detected. Contrasting to alumina support, no strong electron-proton interaction with the protons on the surface of SiO2 (presumably, silanol groups) was found and infiltration of the oiled opal films with gasoline changes the central part of 1 H ENDOR spectra. It shows that the proton containing groups on the surface of amorphous SiO2 sample can significantly change the asphaltene adsorption properties and ENDOR of the intrinsic for oil paramagnetic centers could be used for the characterization of surface state in porous media in situ or operando. PACS: 76.70.Dx, 75.10.Dg, 61.43.Bn.

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Studies of opal crystals infiltrated with iron porphyrin

Cited by 2 publications

References 9 publications

Magnetic circular dichroism of opal crystals infiltrated with iron porphyrin

Magnetic circular dichroism of opal crystals infiltrated with iron porphyrin

Probing the surface of synthetic opals with the vanadyl containing crude oil by using EPR and ENDOR techniques

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