Discrimination of infrared fingerprints of bulk and surface POH and OH of hydroxyapatites

Diallo-Garcia, Sarah; Osman, Manel Ben; Krafft, Jean‐Marc; Boujday, Souhir; Costentin, Guylène

doi:10.1016/j.cattod.2013.11.041

Cited by 36 publications

(86 citation statements)

References 70 publications

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“…Consistently with experimental data obtained by infrared spectroscopy, 35,67,68 it is confirmed from solid state NMR that the surface of the wellcrystallized particles are terminated by protonated phosphates groups (Table 1). If the 31 P fingerprints of these terminated protonated phosphate groups is quite qualitatively similar to that usually described in literature for enriched HPO 4 2− disordered surface layer, the intensity of this contribution is greatly decreased compared to what is observed in biological or biomimetic HAp systems.…”

Section: H Mas Inversion Recoverysupporting

confidence: 91%

“…Thanks to H-D exchanges experiments and to the adsorption of probe molecules, it was possible to identify the infrared fingerprint of terminal OH emerging from the OH tunnels at the surface. 35,54 Corresponding 1 H NMR fingerprint at −0.01 ppm could be obtained in the present work combining the data obtained from the isotopic labeling and 1 H NMR inversion recuperation experiments. From the very similar positions of the infrared or 1 H NMR fingerprints of bulk and surface OH, it can be concluded that the local structure of the related OH at the surface is not deeply modified by surface relaxation processes.…”

Section: Oh Channelsmentioning

confidence: 94%

“…Taking into account that due to the isotopic labeling procedure, the HDAp sample remains more hydrated than that of the HAp one, 35 (Figure 4a, top spectrum). Note that on the contrary, the fact that the signal at 3.1 ppm could not be recovered on the HDAp t-f sample after exposure of this sample to ambient atmosphere confirms its bulk origin.…”

Section: H Mas Inversion Recoverymentioning

confidence: 99%

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Discrimination of Surface and Bulk Structure of Crystalline Hydroxyapatite Nanoparticles by NMR

et al. 2015

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Solid state 1 H and 31 P NMR spectroscopy was used to characterize wellcrystallized hydroxyapatite samples of different stoichiometry prepared by a precipitation route. The aim of the paper was to investigate the bulk structural features of samples with different stoichiometry and to discriminate signals related to the surface from those related to the bulk. Thanks to the implementation of (i) in situ thermal pretreatment at 623 K, (ii) filling of the NMR rotor in a controlled atmosphere, (iii) relative proton enrichment of the surface performed under controlled isotopic H-D exchanges, and (iv) specific NMR sequences including inversion recovery measurements, two-dimensional HETCOR and DQSQ spectra, new resolved NMR signals originating from the surface and from the bulk were identified alongside already reported signals associated with adsorbed water, structural phosphates, and OH groups. In particular, considering the influence of the stoichiometry, it was possible to identify a specific signature associated with defective hydrogenophosphate groups present in the bulk. Despite the well-ordered surface terminations of the nanoparticles, specific surface signals associated with nonprotonated and protonated surface terminating phosphate groups could be identified. In addition, from the three resolved 1 H signals associated with columnar OH channels, two from the bulk and one from the surface, a structural model describing the relative organization of hydroxyl groups running along the c axis inside the columnar OH channel in the well-crystallized particles is proposed: the two types of bulk hydroxyls are associated with the presence of both up and down orientations of their related protons in a same tunnel. Corresponding 1 H signatures of the surface-terminating hydroxyls or structured water molecules emerging from the OH channels were also identified. Moreover, in addition to the broad 5.1 ppm line associated with water adsorbed on calcium cations and hydrogenophosphate groups, the 1.1 ppm line is ascribed to structured external water molecules stacking in continuity to the OH channels.

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Section: H Mas Inversion Recoverysupporting

confidence: 91%

Section: Oh Channelsmentioning

confidence: 94%

Section: H Mas Inversion Recoverymentioning

confidence: 99%

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Discrimination of Surface and Bulk Structure of Crystalline Hydroxyapatite Nanoparticles by NMR

et al. 2015

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“…3. For the hydroxyapatites, stretching vibrations of lattice OH − anions were located between 3500 and 3600 cm −1 [38][39][40][41]. Furthermore, one band was observed around 3665 cm −1 for most of the catalysts.…”

Section: Characterization Of the Catalystsmentioning

confidence: 93%

“…Furthermore, one band was observed around 3665 cm −1 for most of the catalysts. By analogy with deficient hydroxyapatites [38,40,41], it was ascribed to (PO H) stretching vibrations of surface species. On the contrary, because no OH stretching vibrations were observed below 3600 cm −1 for orthophosphates and pyrophosphates, it was concluded that they did not contain hydroxyapatites.…”

Section: Characterization Of the Catalystsmentioning

confidence: 98%

Dehydration of ethyl lactate over alkaline earth phosphates: Performances, effect of water on reaction pathways and active sites

Blanco

Lorentz

Delichère

et al. 2016

Applied Catalysis B: Environmental

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Structure and Surface Study of Hydroxyapatite‐Based Materials

Costentin

Drouet

Salles

et al. 2022

Design and Applications of Hydroxyapatite‐Based Catalysts

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In addition to designing catalytic materials ever more active and selective, the emergence of new classes of greener catalysts remains very challenging. The apatite family system with hydroxyapatite (HA) structure appears as a good candidate for catalysis due to its ecocompatibility properties, its sorption ability toward organic molecules, and its tunable composition resulting into modulation of its surface properties. Depending on their mode of preparation, these inexpensive and environment-friendly apatitic calcium phosphates exhibit properties of relevance to catalysis, such as large surface area and various morphologies.However, most studies focused so far on the catalytic performance of these compounds, while the study of structure-reactivity relationships required for rationalized optimization remains rather limited. This chapter aims at providing tools to help understand the catalytic behavior of apatite compounds, giving details about their structure, surface properties, and reactivity; this will include both stoichiometric and nonstoichiometric compounds, sometimes biomimetic and potentially substituted. A special attention is dedicated to recent advances in the characterization of their structural properties (bulk and surface/interphase) that have a strong impact on their reactivity, through both experimental and computational approaches to study the mechanisms occurring in the structure or at the crystals surface, as well as thermodynamic and dynamical properties. Remaining characterization challenges for apatite-based catalysts will also be discussed. 1.an influence on the charges carried by the cation and on the related strength of the Ca-O interaction [127], which results in different adsorption properties with guest molecules. To go further, quantum calculations coupled with NMR (Nuclear Magnetic Resonance) resultsshowed the impact of the presence of OHions on the migration of Ca 2+ as well as the rotation of PO4 3groups [128]. In the hydroxyapatite structure, phosphate ions PO4 3are the largest components of the structure. As such, they provide a primary backbone via 3D compact-like piling, generating interstitial sites for the other ions of the structure. Metal cations such as Ca 2+ occupy two types of crystallographic sites, denoted Ca1 (4 sites per unit formula) and Ca2 (6 sites per unit formula), see Figure 2. Ca1 sites are localized along the trigonal axis with the coordinates (1/4, 3/4, 1/2) and (3/4, 1/4, 1/2), forming linear columns along the c-axis. Ca2 sites in contrast form equilateral triangles at z = 1/4 and z = 3/4 on the sixfold screw (senary) 63 axes. Adjacent Ca1 and Ca2 sites are linked through shared oxygen atoms from PO4 tetrahedra. Ca1 sites generate (distorted) polyhedra where the metal ion is in ninefold coordination, while in Ca2 sites it is in sevenfold coordination.The Ca2 triangles contribute to delimit so-called "apatitic channels" where ions such as OHare axially located (Figure 3) [116,120]. In calcium hydroxyapatite, the Ca2 triangular sites correspond to the narrow...

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Discrimination of infrared fingerprints of bulk and surface POH and OH of hydroxyapatites

Cited by 36 publications

References 70 publications

Discrimination of Surface and Bulk Structure of Crystalline Hydroxyapatite Nanoparticles by NMR

Discrimination of Surface and Bulk Structure of Crystalline Hydroxyapatite Nanoparticles by NMR

Dehydration of ethyl lactate over alkaline earth phosphates: Performances, effect of water on reaction pathways and active sites

Structure and Surface Study of Hydroxyapatite‐Based Materials

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