Dependent excited state absorption and dynamic of b-BF2 substituted metalloporphyrins: The metal ion effect

authors	Sciuti, LF; Costa, LD; Guieu, S; Cocca, LHZ; Iglesias, BA; Mendonca, CR; Tome, AC; Faustino, MAF; De Boni, L
nationality	International
journal	SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
author keywords	Metalloporphyrins; Porphyrins; Transient absorption technique; Time-resolved spectroscopic techniques; Absorption dynamics; Relaxation dynamics; Lifetime; Intersystem crossing
keywords	NONLINEAR ABSORPTION; ZINC PORPHYRIN; QUANTUM YIELD; COMPLEXES; SPECTRA; CO
abstract	Absorption and relaxation dynamics of electronic states of free-base, Co(II), Cu(II) and Zn(II) porphyrins bearing a b-(2,2-difluoro-1,3,2-dioxaborinin-5-yl) group were investigated in dimethyl sulfoxide by using distinct time-resolved spectroscopic techniques. Furthermore, excited state absorption cross-section spectra were determined by combining white light continuum Z-Scan and transient absorption techniques. In the case of the free-base (2H) and Zn(II) porphyrins, we were able to quantify singlet-triplet conversion by analyzing the evolution of time-resolved fluorescence. Relaxation lifetimes from the excited to the ground state were observed in both porphyrins at nanosecond time scale. However, for Co(II) and Cu(II) metalloporphyrins it was observed in the picosecond time scale through femtosecond transient absorption, indicating that both compounds relax back to the ground state only by internal conversion processes. Co(II) and Cu(II) heavy atoms seem to prohibit the radiative and intersystem crossing processes. (c) 2021 Elsevier B.V. All rights reserved.
publisher	PERGAMON-ELSEVIER SCIENCE LTD
issn	1386-1425
isbn	1873-3557
year published	2021
volume	260
digital object identifier (doi)	10.1016/j.saa.2021.119911
web of science category	9
subject category	Spectroscopy
unique article identifier	WOS:000670125800022