Hybrid Ni-Al layered double hydroxide: Characterization and in situ synchrotron XRD and vibrational spectroscopic studies under high-pressure

Autor(es)

de Matos, Caroline S. ^[1] ; Nobrega, Marcelo M. ^[1] ; Temperini, Marcia L. A. ^[1] ; Constantino, Vera R. L. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Quim, Dept Quim Fundamental, Ave Prof Lineu Prestes 748, BR-05508000 Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: APPLIED CLAY SCIENCE; v. 174, p. 152-158, JUN 15 2019.
• Citações Web of Science: 0

Resumo

Anions from 2-aminoterephthalic acid (ATA), an aniline derivative, were intercalated into layered double hydroxide (LDH), and submitted to high-pressures by using a diamond anvil cell to access possible transformations of guest species in confined environment. The hybrid material, constituted by Ni2+ and Al3+ in a molar ratio equal to 2 (Ni2Al-ATA), was characterized by mass spectrometry coupled thermal analysis (TGA-DSC-MS), X-ray diffractometry (XRD) and vibrational spectroscopy (infrared and Raman) at ambient pressure. The response of Ni2Al-ATA to the pressure stimuli was monitored by in situ synchrotron XRD and in situ vibrational spectroscopies (infrared and Raman), during the compression-decompression cycle up to 14-16 GPa. XRD reflections related to (00l) stacking planes of hybrid material presented broadening and intensities decreasing, pointing out a pressure-induced amorphization. XRD profile of Ni2Al-ATA was not recovered after decompression, indicating that the structural modification promoted by the pressure to the inorganic matrix is irreversible. In-situ vibrational spectroscopy as a function of pressure revealed a minor modification in the spectrum of ATA anion confined into LDH (for example, the Raman intensity decreasing (without shift) of the 1612 cm(-1) band). Spectral features were recovered after the decompression, suggesting no decomposition or reactivity of the organic guest species between the LDH layers. On the other hand, Raman spectrum of 2-aminoterephthalic acid (non-intercalated) changed expressively during the decompression step and sample become completely luminescent at 1.7 GPa and at ambient pressure. Probably LDH decreases the guest reactivity by a steric blockage imposed by ATA arrangement in the confined environment, which can improve the guest stability submitted to high-pressure stimulus. (AU)

• Processo FAPESP: 16/21070-5 - Espectroscopia vibracional com resolução espacial
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• Processo FAPESP: 15/09763-2 - Síntese e reatividade de anilina e compósitos de polianilina-ouro em alta pressão
• Beneficiário: Marcelo Medre Nobrega
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• Processo FAPESP: 14/04816-8 - Desenvolvimento de estruturas hierárquicas com nanoarquiteturas baseadas em unidades lamelares inorgânicas
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• Beneficiário: Marcelo Medre Nobrega
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