TEDE Communidade: Ciência dos materiais é o campo da ciência de caráter interdisciplinar relativo ao estudo das propriedades dos materiais e a relação entre a sua estrutura em escalas atômicas ou moleculares com suas características macroscópicas, incorporando elementos da física e da química como as formas de caracterização e processamento.Ciência dos materiais é o campo da ciência de caráter interdisciplinar relativo ao estudo das propriedades dos materiais e a relação entre a sua estrutura em escalas atômicas ou moleculares com suas características macroscópicas, incorporando elementos da física e da química como as formas de caracterização e processamento.https://tedebc.ufma.br/jspui/handle/tede/12662026-04-07T12:57:20Z2026-04-07T12:57:20ZEstudo teórico baseado na teoria do funcional da densidade das propriedades estruturais, eletrônicas e ópticas dos cristais de sarcosina e DL-alanina em função da pressãoMOURA, Geanso Miranda dehttps://tedebc.ufma.br/jspui/handle/tede/67932026-02-25T11:52:31Z2025-06-30T00:00:00ZTítulo: Estudo teórico baseado na teoria do funcional da densidade das propriedades estruturais, eletrônicas e ópticas dos cristais de sarcosina e DL-alanina em função da pressão
Autor: MOURA, Geanso Miranda de
Primeiro orientador: ANDRADE FILHO, Tarciso Silva de
Abstract: The study of the structural and electronic properties of amino acid crystals under different
pressure conditions is highly relevant, as these materials have potential for technological
applications. Understanding how pressure influences the characteristics of organic crystals
can lead to significant advances in the development of new compounds and the optimization
of industrial processes. Thus, this research not only advances theoretical knowledge about
these systems but also paves the way for technological innovations. The methodology
adopted for the computational calculations in this study is based on Density Functional
Theory (DFT), using the Quantum ESPRESSO software. The Projector Augmented Wave
(PAW) method was employed to perform the computational calculations, and the exchange-
correlation components were described using the Perdew-Burke-Ernzerhof (PBE/GGA),
PBE for solids (PBEsol/GGA), revised PBE (revPBE/GGA), and the non-local van der
Waals correlation functional (vdW-DF). Additionally, the Grimme D3 dispersion term
was applied in conjunction with all GGA functionals to correct for dispersion interactions.
Geometry optimization was considered converged at 10−3
eV· Å−1
. In this research, the
structural and electronic properties of sarcosine and DL-alanine crystals were investigated
under extreme hydrostatic pressure conditions, with special attention to lattice parameters
and hydrogen bond behavior. For sarcosine, discrete pressure points ranging from 0.0
to 3,7 GPa were used, while for DL-alanine the applied pressure ranged from 0,0 to
18 GPa. The computational results for the optimized lattice parameters a, b, and c and
the volume of sarcosine at ambient pressure show deviations of less than 2% compared to
experimental values reported in the literature. Regarding electronic properties, sarcosine
exhibits a direct band gap at ambient pressure (along the Γ point). The calculated band
gap was approximately 5.20 eV, indicating insulating behavior in this configuration. Under
pressure, sarcosine displays anisotropic behavior and a theoretical bulk modulus B0 of
about 6.98 GPa. Furthermore, the band gap of sarcosine does not decrease monotonically
with pressure; it initially decreases from 5,20 eV to 4,90 eV up to approximately 1,4 GPa,
then slightly increases, reaching 5,05 eV at 3,7 GPa. This non-linear behavior is interpreted
as a result of competition between unit cell contraction and molecular rotation within
the crystal. In terms of optical properties, the static dielectric constant showed values
of 2,08 in the xx plane, 2,47 in the yy plane, and 2,17 in the zz plane, with the highest
polarity in the yy plane, reinforcing the system’s anisotropic behavior. Strong absorption
in the ultraviolet region indicates potential application as ultraviolet light polarizers. For
DL-alanine, the computational results for the optimized lattice parameters and unit cell
volume decrease continuously with increasing pressure, showing excellent agreement with
available experimental data. Additionally, the b parameter decreased by approximately
14%, indicating greater flexibility of the crystal in this direction. Under pressure up to
18 GPa, DL-alanine exhibits anisotropic behavior and a theoretical bulk modulus B0 of
about 8.48 GPa. Regarding the theoretical value of the crystalline dipole moment, the
value obtained at ambient pressure was approximately 75 Debye, while above 15 GPa
a sharp drop is observed, reaching approximately 38 Debye at 17,5 GPa. The voids are
also drastically minimized, ranging from 84,76 Å3 at ambient pressure to values below
3,94 Å3 at pressures above 16,4 GPa - a reduction of approximately 95%. The results
presented here are essential for a deeper understanding of the potential technological
applications of sarcosine and DL-alanine in different scenarios, highlighting the relevance
of theoretical studies dedicated to the investigation of crystalline systems under high-
pressure conditions. This research deepens the understanding of intermolecular interactions,
as well as the optical, structural, and electronic properties of organic crystals, establishing
a solid foundation for future investigations in the field of materials science.
Instituição: Universidade Federal do Maranhão
Tipo do documento: Tese2025-06-30T00:00:00ZPropriedades estruturais, espectroscópicas e térmicas do sal de Tutton Rb2Co(SO4)2(H2O)6: uma abordagem experimental e teórica visando aplicações em dispositivos ópticosGOMES, Letícia Fonsecahttps://tedebc.ufma.br/jspui/handle/tede/67882026-02-24T12:17:39Z2025-12-22T00:00:00ZTítulo: Propriedades estruturais, espectroscópicas e térmicas do sal de Tutton Rb2Co(SO4)2(H2O)6: uma abordagem experimental e teórica visando aplicações em dispositivos ópticos
Autor: GOMES, Letícia Fonseca
Primeiro orientador: OLIVEIRA NETO, João Gomes de
Abstract: This work investigates the structural, spectroscopic, thermal, and optical properties of
the Rb2Co(SO4)2(H2O)6 crystal, a Tutton salt with potential application in selective
optical devices. The material was synthesized by slow solvent evaporation and
characterized by powder X-ray diffraction (PXRD) with Rietveld refinement, Fourier-
transform infrared (FT-IR) and Raman spectroscopies, thermogravimetric and
differential scanning calorimetry (TG-DSC) analyses, and ultraviolet–visible–near
infrared (UV-Vis-NIR) spectroscopy. The monoclinic crystal structure, belonging to the
P21/a space group, was confirmed, with lattice parameters consistent with literature data.
The analysis of intermolecular interactions, via Hirshfeld surfaces and calculations of
crystal voids, revealed a dense lattice packing, predominantly governed by O···H/H···O
hydrogen bonds, O···Co/Co···O coordination interactions, and Rb···O/O···Rb
electrostatic interactions. Periodic calculations based on Density Functional Theory
(DFT) indicated an electronic band gap of approximately 3.0 eV, mainly associated with
the contributions of the Co2+ ion's d orbitals. Vibrational characterization allowed for the
suitable assignment of Raman and FT-IR modes based on the structural units
[Co(H2O)6]
2+, [SO4]
2-
, and Rb+
. TG-DSC analyses revealed a dehydration event at
approximately 111 °C, with the associated enthalpy for the dehydration process. The
optical study showed absorption bands in the UV region associated with ligand-to-metal
charge transfer transitions and bands in the Vis region attributed to d-d electronic
transitions of the Co2+ ion, evidencing the Jahn-Teller effect. The observed absorption
and transmittance windows indicate the material's intrinsic spectral selectivity,
reinforcing its potential for applications in optical filters and selective photonic systems.
Instituição: Universidade Federal do Maranhão
Tipo do documento: Dissertação2025-12-22T00:00:00ZSíntese, caracterização e estudos computacionais do fármaco etionamida e suas dispersões sólidas com ácido mandélico e ácido ftálicoBEZERRA, Raychimam Douglas Santanahttps://tedebc.ufma.br/jspui/handle/tede/67612026-02-05T16:15:45Z2025-12-26T00:00:00ZTítulo: Síntese, caracterização e estudos computacionais do fármaco etionamida e suas dispersões sólidas com ácido mandélico e ácido ftálico
Autor: BEZERRA, Raychimam Douglas Santana
Primeiro orientador: OLIVEIRA NETO, João Gomes de
Abstract: This work presents the structural, spectroscopic, thermal, and computational investigation
of different solid systems involving Ethionamide (ETH), a second-line drug widely used
in the treatment of multidrug-resistant tuberculosis (MDR-TB), whose low solubility
limits its bioavailability. Three distinct approaches were studied: the pure crystalline form
of ETH, the coamorphous ETH–Mandelic Acid (MAD) system, and the pharmaceutical
salt ETH–Phthalic Acid (PHT), with the aim of understanding and optimizing their
physicochemical and biopharmaceutical properties. The compounds were obtained using
the slow solvent evaporation method in different media (methanol and ethanol) and
characterized by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR)
spectroscopy, Raman spectroscopy, thermal analyses, density functional theory (DFT)
calculations, and Hirshfeld surface analyses. The crystalline form of ETH exhibited a
monoclinic system (space group C1c1) stabilized mainly by H⋯H and H⋯S/S⋯H
contacts, with dispersion energy accounting for approximately 60% of the total
stabilization. Thermal analysis indicated stability up to 162 °C, and DFT calculations
revealed a high electronic gap(HOMO–LUMO) (7.84–8.09 eV), supporting its low reactivity.
The study of the coamorphous ETH–MAD system, prepared in 1:2 and 1:3 ratios,
demonstrated the formation of an amorphous phase stabilized by hydrogen bonds
between the NH2 groups of ETH and the C=O groups of MAD. The solid dispersions
exhibited glass transition temperatures of 59 °C (1:2 ratio) and 61 °C (1:3 ratio),
indicating good stability in the amorphous phase. In addition, the amorphous ETH–MAD
(1:3) system remained stable in the amorphous state for up to 150 days. Dissolution tests
showed a 3.58-fold increase in the solubility of ETH in the coamorphous system
compared to the crystalline form, as well as controlled drug release when encapsulated in
sodium alginate beads. The pharmaceutical salt ETH–PHT was obtained as a triclinic
crystalline system (space group P1̅), stabilized by a strong N–H+···O− hydrogen bond (d
= 1.742 Å). Thermal analyses revealed stability up to approximately 339 K, with
endothermic events characteristic of melting and decomposition. Electronic analysis
showed a direct band gap of 1.58 eV, indicating higher conductivity and enhanced
pharmacological potential. Furthermore, periodic DFT calculations demonstrated the
thermodynamic stability of the salt, with entropy increasing to 2192 kJ/mol·K and
enthalpy to 957 kJ/mol at 1000 K, while the Gibbs free energy decreased, suggesting
spontaneous phase reorganization. Dissolution studies under physiological pH (6.8; 37
°C) showed solubility 2.44 times greater than pure ETH (1.01 mg/mL versus 0.41
mg/mL). The results demonstrate that solid-state modifications of Ethionamide, through
the formation of coamorphous systems and pharmaceutical salts, significantly enhance
solubility, thermal stability, and controlled-release properties. Such advances reinforce
the potential of these approaches as effective strategies for the development of optimized
formulations aimed at treating multidrug-resistant tuberculosis.
Instituição: Universidade Federal do Maranhão
Tipo do documento: Tese2025-12-26T00:00:00ZSíntese, caracterização e avaliação do desempenho biológico de micropartículas polissacarídicas contendo nimesulida e azitromicinaPINHO, Ellen Karolyne da Silvahttps://tedebc.ufma.br/jspui/handle/tede/67542026-02-03T15:25:19Z2025-12-22T00:00:00ZTítulo: Síntese, caracterização e avaliação do desempenho biológico de micropartículas polissacarídicas contendo nimesulida e azitromicina
Autor: PINHO, Ellen Karolyne da Silva
Primeiro orientador: SOUSA, Francisco Ferreira de
Abstract: Oral administration of drugs, such as the anti-inflammatory nimesulide (NIM) and the
antibacterial azithromycin (AZI), can cause adverse gastrointestinal effects. A technological
strategy for mitigating these adverse effects is the combination of these drugs with
polysaccharide-based delivery systems. In this work, we propose the synthesis,
characterization, and evaluation of the biological performance of polysaccharide-based
microparticles composed of sodium alginate (NaCHO) and chitosan (NCHO) cross-linked with
calcium chloride (CaCl2), for the drug delivery of NIM and AZI. The microparticles (NaCHO-
NIM-CaCl2, NaCHO-AZI-CaCl2, NCHO-NIM-CaCl2, and NCHO-AZI-CaCl2) were produced
by adapting methods of calcium-induced ionotropic gelation, sonication, and solvent
evaporation. The samples were characterized for their physicochemical properties using X-ray
diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy
(EDS), Raman spectroscopy, and Fourier-transform infrared spectroscopy (FT-IR). To
complement the characterization, theoretical studies of vibrational and electronic properties
were conducted using density functional theory (DFT). For proof of concept, cell viability
assays and in vitro release studies were performed to evaluate the potential biological
application of the microparticles.
Instituição: Universidade Federal do Maranhão
Tipo do documento: Tese2025-12-22T00:00:00Z