Banca de QUALIFICAÇÃO: ANNA CAROLINE FEITOSA LIMA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : ANNA CAROLINE FEITOSA LIMA
DATE: 26/02/2024
TIME: 14:00
LOCAL: Ambiente virtural Google Meet
TITLE:

COMPUTATIONAL MODELING OF STRUCTURAL AND ELECTRONIC PROPERTIES OF MELOFEN-TYPE LIGANDS AND THEIR Co(II)- and Cu(II)-COMPLEXES

KEY WORDS:

Schiff bases, Melophen complexes, Computational Modeling, DFT.

PAGES: 107
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Química Teórica
SUMMARY:

The diverse applications in the fields of electrochemistry, biology and materials science, as well as the prominent historical role of metallic Schiff based complexes, especially those from the Salens/Salofens family, motivated the research and development of new structurally similar ligands called Melens/Melofens. There is broad interest in the analysis and application of this family of ligands coordinated to metal ions in the synthesis of new materials. In particular, applications that depend on the understanding of oxidation and reduction processes are highlighted and can be analyzed considering the electronic and structural properties of the ligands and coordination compounds formed. Molecular modeling tools are viable alternatives for understanding these mechanisms and optimizing the combinations between synthesized compounds and metals in each application, guiding future experiments and applications. Among the existing methodologies, DFT has been widely used. For the present work, DFT and TD-DFT were used to carry out a systematic study and definition of the best calculation levels for the new melofen ligands and Co(II)- and Cu(II)-melofen complexes. To this end, a systematic study was initially carried out using DFT methods to determine the appropriate level of theory to obtain the molecular structure and wavelength of maximum absorption, l_max, in the UV-Vis absorption spectrum of the new melofen-type ligands. For the melofen3a-b ligands, comparison of absorption spectroscopy data in the UV-Vis region obtained with the experimental one suggests that the B3LYP def2-QZVP level of theory (structure and excited electronic states) is the most appropriate, presenting the lowest errors compared to the other calculation levels tested (B3LYP, BLYP, M06L, P3PW and basis sets 6-31G, Def2-TZVP and Def2-QZVP). For melofen3c-d, the M06L functional presented results closer to the values found experimentally, respectively for the def2-TZVP and def2-QZVP basis sets. Subsequently, with the aim of selecting an appropriate level of theory to investigate the Co(II)- and Cu(II)-melofen complexes, a systematic study of analogous de Fe(III)-complexes of salofen ligands ([Fe(L¹)(N³)(C₂H₅OH)] (1) e [Fe(L²)(N₃)(C₂H₅OH)]), was carried out, based on data from the literature on X-ray crystallography. The B3LYP functional proved to be more suitable than PBE0 to represent both structures, as shown by the RMSD values. The def2-QZVP and def2-TZVP basis sets best represented complexes 1 and 2, respectively. However, due to the higher computational demand, the evaluated option 6-31G can be used, without significant loss of precision. It is expected that the results obtained can assist in the investigation of new melofen complexes, which, due to the scarcity of experimental and/or computational data, could have a great contribution to the establishment of an appropriate calculation protocol for complexes of this type and the investigation that will be carried out on various properties (structural and electronic, electrical properties, nonlinear optics, metal-ligand transfer states, luminescence and reactivity, may be investigated, depending on the metal ion used), which may expand the scope of applications of such complexes.

COMMITTEE MEMBERS:
Presidente - ***.999.014-** - JULIANA ANGEIRAS BATISTA DA SILVA - UFPE
Interno - JOAO RUFINO DE FREITAS FILHO
Externo à Instituição - SIDNEY RAMOS DE SANTANA - UFPB
Externa à Instituição - KEYLA MIRELLY NUNES DE SOUZA