Banca de DEFESA: JANILSON ALVES FERREIRA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : JANILSON ALVES FERREIRA
DATE: 24/05/2022
TIME: 09:00
LOCAL: plataforma virtual
TITLE:

POLYMORPHOUS LUMINESCENT COMPOUNDS APPLIED AS DEVELOPERS OF LATENT FINGERPRINTS

KEY WORDS:

Luminescence; Gel; Crystal Europium; Papilloscopy; Zwitterion.

PAGES: 126
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUMMARY:

In this work, synthetic routes were presented to obtain luminescent materials, presenting polymorphism, obtained by the same precursor materials under magnetic stirring, at different temperature parameters. A zwitterion 3-(1methylimidazolium-1-yl) butane-1-sufonate as a ligand was mixed with Eu³⁺ ion at room temperature for 24 hours to obtain the EuZ_gel system and at 80 ºC for 12 hours to obtain the EuZ_crystal system. Their chemical, structural and photophysical properties were sequentially analyzed to apply them as latent fingerprint (IDL) revealing agents.

Through elemental analysis, the minimum formula 2(N₂C₄H₄).3(SO₃).(NEu).9H₂O was proposed for both systems. The purity and preservation of the zwitterion structure was estimated through the displacement signals by Nuclear Magnetic Resonance (NMR). The structural investigation of the EuZ_gel and EuZ_crystal compounds started with the Infrared technique (FTIR), in which bands were identified at 3500 cm^-1 corresponding to the OH group, which proved to be wider for the extended system, when compared to the solid system, and also, indicative of coordination by the S=0 terminal, with signals between 1009 – 1294 cm^-1 for the two synthesized materials. Such events were confirmed by the use of the Raman scattering technique. The new crystalline profile was identified through x-ray diffractogram for the EuZcristal system, as well as the gel character of the EuZgel system identified by rotational and oscillatory rheology techniques, inferring on the solid behavior of the system superior to the liquid character present.

The thermal stability of the materials was analyzed by thermogravimetry and significant degradation changes were noticed from 270 ºC, with the degradation of the butyl chain present in the organic structure of the zwitterion, generating residues by thermal effect at approximately 650 ºC for the EuZ_gel system and 900 °C for the EuZ_crystal system. The phase transformation that occurred from the gel to the crystal was identified by differential scanning calorimetry (DSC), identifying the crystal formation temperature around 232 ºC, with the intermediate transformation steps monitored by Scanning Electron Microscopy (SEM). The systems had their spectroscopic identities explored, by the technique of absorption in the ultraviolet-visible region, band centers were assigned at 214 nm; 288 nm and 301 nm for Eu_Zcrystal; zwitterion and EuZ_gel, respectively. And through the excitation of the systems at 395 nm, photoluminescence spectra were obtained, monitoring the emission at 615 nm (⁵D₀→⁷F₂) and estimated lifetimes in the excited state in the order of 0.23 ms for the gelled system and 1, 53 ms for the crystalline system. The theoretical study about the geometry around the central ion (Eu³⁺) was carried out by calculating the excited states by the Luminescence Package (LUMPAC) and the three-dimensional geometric coordination optimized by the Recife Model 1 (RM1) program.

Knowing the thermal and chemical properties of the materials obtained, combined with the luminescence profile studied, the systems were simultaneously applied as latent fingerprint revealing agents, using a whorl pattern print, with previously identified characteristic points. Sixty fingerprints were collected on glass slides, where half of them were submitted to development by EuZ_crystal material and the other half, transferred to collection tape, for deposition in the form of EuZ_gel system film, corresponding to 30 days of monitoring of the impressions. These papillary records showed the efficiency of the compounds in the performance of the elucidation of papillary lines over time, with luminescent and visual efficiency until the 10th day of collection for the gel phase enhancer and efficiency until the 30th day in the use of the system in the crystalline phase.

BANKING MEMBERS:
Externo à Instituição - CICERO INÁCIO DA SILVA FILHO
Interno - 2457389 - EDUARDO PADRON HERNANDEZ
Externa ao Programa - 3218211 - MARCELLA AUXILIADORA DE MELO LUCENA
Externa à Instituição - ROBERTA CLAÚDIA SANTOS NEVES - UFPE
Presidente - 1354207 - SEVERINO ALVES JUNIOR