Browsing by Author "Nikitin T."

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Optical and Electric Properties of the Organic-Inorganic Hybrid bis(2-amino-5-picolinium) Tetrachlorocobaltate(II) [(C6H9N2)2CoCl4]
(Elsevier, 2024) Ghoudi, A.; Chaabane I.; Naouari, Raja; Aydi A.; Oueslati A.; Dhahri E.; Costa B.F.O.; Nikitin T.; Paixão J.A.; FAUSTO, RUI
Organic-inorganic hybrid materials have garnered considerable interest due to their unique physical and chemical properties, enabling their use in diverse applications. This study explores the synthesis and characterization of the organic-inorganic hybrid compound (C6H9N2)2CoCl4. The compound was successfully synthesized via the slow evaporation method at room temperature. The X-ray diffraction on a single crystal indicated a monoclinic structure in the P21/c space group. Various analytical techniques were employed to ensure the material's high purity and to investigate its properties. Powder X-ray diffraction and SEM/EDX analysis confirmed the compound's crystalline structure and elemental composition. Raman spectroscopy provided insights into the vibrational characteristics. In contrast, UV-visible absorption and luminescence spectroscopy were used to explore its optical properties, indicating its potential as a semiconductor. The electrical and dielectric properties were studied using complex impedance spectroscopy (CIS), revealing significant frequency and temperature dependence. Additionally, Kohlrausch-Williams-Watts analysis was employed to examine the electric modulus, further elucidating the compound's non-Debye behavior. These methods collectively demonstrate the compound's potential applications in electronic and optical devices.
Open Access
Phenylpropiolic Acid Isolated in Cryogenic Nitrogen and Xenon Matrices: NIR and UV-Induced Study
(AIP Publishing, 2023) Lopes S.; Nikitin T.; FAUSTO, RUI
Phenylpropiolic acid (C6H5C≡CCOOH, PPA) isolated in nitrogen and xenon cryogenic matrices was studied by infrared spectroscopy. The experimental studies were complemented by a series of quantum chemical calculations carried out at the density functional theory (B3LYP) and MP2 levels of theory (with different basis sets). The calculations predicted the existence of two planar PPA conformers, differing in the arrangement of the carboxylic group. The higher-energy trans-PPA conformer has a negligible population in the gas phase at room temperature and was prepared in situ in the N2 cryomatrix through vibrationally-induced rotamerization of the lower-energy cis-PPA conformer, achieved using selective narrowband infrared excitation of the OH stretching coordinate of the latter species. Broadband UV (λ > 235 nm) irradiation of matrix-isolated cis-PPA was also undertaken, leading to the observation of cis-PPA → trans-PPA isomerization. No other UV-induced photoreactions were observed. The in situ generated trans-PPA conformer was found to decay back to cis-PPA in the dark by tunneling, and its lifetimes under different experimental conditions were determined. The assignment of the infrared spectra of both conformers is presented, considerably extending the vibrational information available on this molecule.