Title: Spectroscopic analysis of boron porphyrin complexes

Authors: Nina Novikova; Penelope J. Brothers; M. Cather Simpson

Addresses: School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand ' School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand ' School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand

Abstract: Spectroscopic analyses of diboron porphyrin complexes have been performed using femtosecond transient absorption spectroscopy, fluorescence spectroscopy measurements, IR and Raman spectroscopy as well as DFT and TDDFT calculations. Transient absorption spectroscopy was used to study the dynamics of the transient species by exciting the molecule with a ~100 fs pulse of light at the wavelength corresponding to the Soret and Q band absorptions of the complexes and recording the spectra at various time delays after the excitation. Two boron porphyrin complexes, B2OF2(TTP) and B2OPh(OH)(TTP) were analysed using UV/Vis absorption and fluorescence spectroscopy, and in the case of B2OF2(TTP) using DFT/TDDFT calculations and transient absorption spectroscopy. A short component with a risetime of τ = 1.79 ± 0.028 ps was observed and assigned as internal conversion from an optically dark S2 state. Two more components were observed as a signal decay of τ = 103 ± 3.45 ps (during S1 excitation) and τ > 4 ns (during S1 and S2 excitations). The observed high molar extinction coefficient, large Stokes shifts, sharp emission profile and in the case of B2OF2(TTP), improved fluorescence quantum yields and long lived excited state, make them good candidates for application as fluorescent dyes.

Keywords: boron porphyrin complexes; transient absorption spectroscopy; femtosecond; time resolved; fluorescence spectroscopy; fluorescent dyes; nanotechnology.

DOI: 10.1504/IJNT.2014.060594

International Journal of Nanotechnology, 2014 Vol.11 No.5/6/7/8, pp.713 - 723

Published online: 20 Apr 2014 *

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