Synthesis of Hybrid Organo−Mineral Materials:  Anionic Tetraphenylporphyrins in Layered Double Hydroxides

Abstract

meso-Tetrakis(p-carboxyphenyl)porphyrin (pTCPP), the atropoisomer (RRRR) of mesotetrakis(o-carboxyphenyl)porphyrin (oTCPP), and the ammonium salt of the meso-tetrakis-(p-sulfonatophenyl)porphyrin (noted pTSPP) were intercalated into [Zn-Al] layered double hydroxide (LDH) using different preparative methods. Coprecipitation at constant pH in a porphyrinic solution of zinc and aluminum salts or anionic exchange of pTCPP on a [Zn-Al-Cl] precursor led to pure LDH phases, while products obtained from the calcinationreconstruction method on a [Zn-Al-Cl] precursor contain a significant amount of ZnO. Powder X-ray diffraction and UV-visible diffuse reflectance spectroscopy of LDH intercalated with pTCPP, oTCPP, and pTSPP show complete intercalation. Interlayer spacing ranging from 18.54 Å for [Zn-Al-oTCPP] to 22.91 Å for [Zn-Al-pTSPP] and 22.73 Å for [Zn-Al-pTCPP], determined from PXRD patterns, reveal different orientations of the anionic macrocyles between the hyroxylated layers. This selective arrangement is discussed in terms of layer charge density, isomeric substitution of the anionic groups on the meso tetraphenylporphyrins, and guest molecules and host matrix interactions.

Factors Affecting the Interlayer Arrangement of Transition Metal–Ethylenediaminetetraacetate Complexes Intercalated in Mg/Al Layered Double Hydroxides

“…In general, when atoms with large scattering power are located at different positions along the c axis, the usual pattern of decreasing intensities of successive (00l) reflections with increasing l is not observed because of the fluctuations in the one-dimensional electron-density distribution along the c axis. [2,4,25,[43][44][45] When the intensity of the (006) reflection is greater than that of (003), as is the case for LDH-3.0-[ZnY], it has been proposed that the heavy metal atom is located at the midpoint of the interlayer galleries. [2,4,25,44] In LDH-2.0-[ZnY], the intensity of the (009) reflection is greater than that of (006), suggesting that the alternate heavy metal centers are located above and below the midpoint of the interlayer galleries.…”

“…[2,4,25,44] In LDH-2.0-[ZnY], the intensity of the (009) reflection is greater than that of (006), suggesting that the alternate heavy metal centers are located above and below the midpoint of the interlayer galleries. [4,43,45] When the Mg/Al molar ratio is increased to 2.2 no significant changes are observed (Figure 3b), suggesting there is only a single phase corresponding to a basal spacing of 1.445 nm. However, on further increasing the Mg/Al molar ratio, LDH-2.5-[ZnY] shows a complicated pattern of broad XRD reflections suggesting that two or more phases (Figure 3c), with different basal spacings, are present; the intensity of the third harmonic reflection (009) also decreases much more than that of the other (00l) reflections.…”

Catalytic activity in oxidation reactions of anionic iron(III) porphyrins immobilized on raw and grafted chrysotile

“…25,26 Grafting reactions can occur by establishing covalent bonds between the reactive groups of the layer and an adequate reactant molecule, which ensures higher chemical, structural and thermal stability for the compound. These reactions can be restricted to the crystal surface (the basal spacing remains unchanged) or layer surface (in this case an interlayer expansion occurs, if the single layers are restacked).…”

Nanocomposite-based controlled release formulation of an herbicide, 2,4-dichlorophenoxyacetate incapsulated in zinc–aluminium-layered double hydroxide

“…In this method, the host and the guest species are included in the mother liquor, followed by aging process to form a well-ordered nanolayered structure. On the other hand, insertion of the guests can also be done by first preparing the host followed by modification or further treatment of the host and finally insertion of the guest molecule into the interlayer [11].…”