Evolution of electronic and vibronic transitions in metal(II) meso-tetra(4-pyridyl)porphyrins

J M S Lopes; R N Sampaio; A S Ito; A A Batista; A E H Machado; P T Araujo; N M Barbosa Neto

doi:10.1016/j.saa.2019.02.024

Evolution of electronic and vibronic transitions in metal(II) meso-tetra(4-pyridyl)porphyrins

Spectrochim Acta A Mol Biomol Spectrosc. 2019 May 15:215:327-333. doi: 10.1016/j.saa.2019.02.024. Epub 2019 Feb 11.

Authors

J M S Lopes¹, R N Sampaio², A S Ito³, A A Batista⁴, A E H Machado⁵, P T Araujo⁶, N M Barbosa Neto⁷

Affiliations

¹ Instituto de Ciências Exatas e Naturais, Programa de Pos-Graduação em Fisica, Universidade Federal do Pará, Belém, PA, Brazil.
² Department of Chemistry, The University of North Carolina at Chapel Hill, Murray Hall, Chapel Hill, NC, United States.
³ Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
⁴ Departamento de Química, Universidade Federal de São Carlos, São Carlos, SP, Brazil.
⁵ Instituto de Química, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil.
⁶ Instituto de Ciências Exatas e Naturais, Programa de Pos-Graduação em Fisica, Universidade Federal do Pará, Belém, PA, Brazil; Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL, United States; Center for Materials for Information Technology (MINT Center), University of Alabama, Tuscaloosa, AL, United States. Electronic address: paulo.t.araujo@ua.edu.
⁷ Instituto de Ciências Exatas e Naturais, Programa de Pos-Graduação em Fisica, Universidade Federal do Pará, Belém, PA, Brazil. Electronic address: barbosaneto@ufpa.br.

PMID: 30852279
DOI: 10.1016/j.saa.2019.02.024

Abstract

The changing of the electronic and vibronic states due to the insertion of Zn(II), Cu(II), Ni(II) or Co(II) ions in the meso-tetrakis(4-pyridyl)porphyrin ring center is investigated. The combination of absorption, photoluminescence, Raman and infrared spectroscopies with second-derivative-based spectral deconvolution analysis reveals that the structuration of both B- and Q-bands is very sensitive to the decorating ion. Similar to free base porphyrins, metal(II) meso-tetra(4-pyridyl)porphyrins also present their Q-band constituted of multiple electronic transitions, where the central ion plays an important role in the selection of vibration modes that mediate the vibronic transitions. Our novel results will expand and reinterpret current assignments for metal(II) meso-tetra(4-pyridyl)porphyrins vibrational modes available in the literature.

Keywords: Metal(II) meso-tetra(4-pyridyl)porphyrins; Molecular symmetry; Multiple electronic transitions; Second derivative analysis.