Enhanced S₂ Fluorescence from a Free-Base Tetraphenylporphyrin Surface-Mounted Metal Organic Framework

Abstract

The ultrafast transient dynamics of a free-base tetraphenylporphyrin (H 2 TPP) surface-mounted metal organic framework (SURMOF) is spectroscopically characterized and compared with that of H 2 TPP in ethanol solution. A dramatic increase of the quantum yield of the Soret band fluorescence (S 2 → S 0 ) is observed in the H 2 TPP−SURMOF, which is accompanied by an increase of the S 2 fluorescence lifetime and a broadening of the fluorescence spectra. In contrast, the Q band (S 1 ) fluorescence is strongly quenched in the H 2 TTP SURMOF compared with the fluorescence of H 2 TTP in ethanol solution. The observed transient absorption kinetics supports the fluorescence data. The enhanced fluorescence in the SURMOF compared with H 2 TPP in solution is attributed to the combination of two factors: the alignment of the vibrational energy levels of the dominant Franck−Condon active mode of the Soret and Q bands and the weaker coupling of these modes to the environment.

Investigation of Morphology‐Controlled Ultrafast Relaxation Processes of Aggregated Porphyrin

“…The S 2 fluorescence lifetime for J‐type aggregated porphyrin is found to be varied from 130 fs to 1 ps . Sun and coworker have reported the fluorescence lifetime of S 2 state is 1.1–13 ps . Again, it is reported that the lifetime of S 2 ‐fluorescence varies from 1.4 ps to 3.4 ps with varying solvents .…”

“…[34,36,38,52] Sun and coworker have reported the fluorescence lifetime of S 2 state is 1.1-13 ps. [53] Again, it is reported that the lifetime of S 2 -fluorescence varies from 1.4 ps to 3.4 ps with varying solvents. [50,[54][55][56] With the disappearance of this stimulated emission, a rise time is observed which is same as the S 2 fluorescence lifetime.…”

Bodipy-Containing Porous Microcapsules for Flow Heterogeneous Photocatalysis

“…The femtosecond transient absorption spectra were obtained using a lab-made femtosecond pump–probe setup with 50 fs time resolution (see the details in the Supporting Information). − The adsorption and desorption isotherms were obtained using an Autosorb iQ gas sorption analyzer (Quantachrome, USA) using N 2 at 77 K. The sample was outgassed at 150 °C for 5 h before the measurement. The specific surface areas were obtained using the Brunauer–Emmett–Teller method.…”

Monitoring of Nonadiabatic Effects in Individual Chromophores by Femtosecond Double-Pump Single-Molecule Spectroscopy: A Model Study

“…The potential energy functions of the states |e1〉 and |e2〉 cross at Q=1.8 (see Figure 1). The chromophore parameters are taken from a recent model describing the photophysics of the B and Qy states of free-base tetraphenylporphyrin [30]. Obviously, SM signals depend on specific values of the model parameters.…”