Excited‐State Deactivation of Branched Phthalocyanine Compounds

Abstract

The excited-state relaxation dynamics and chromophore interactions in two phthalocyanine compounds (bis- and trisphthalocyanines) are studied by using steady-state and femtosecond transient absorption spectral measurements, where the excited-state energy-transfer mechanism is explored. By exciting phthalocyanine compounds to their second electronically excited states and probing the subsequent relaxation dynamics, a multitude of deactivation pathways are identified. The transient absorption spectra show the relaxation pathway from the exciton state to excimer state and then back to the ground state in bisphthalocyanine (bis-Pc). In trisphthalocyanine (tris-Pc), the monomeric and dimeric subunits are excited and the excitation energy transfers from the monomeric vibrationally hot S1 state to the exciton state of a pre-associated dimer, with subsequent relaxation to the ground state through the excimer state. The theoretical calculations and steady-state spectra also show a face-to-face conformation in bis-Pc, whereas in tris-Pc, two of the three phthalocyanine branches form a pre-associated face-to-face dimeric conformation with the third one acting as a monomeric unit; this is consistent with the results of the transient absorption experiments from the perspective of molecular structure. The detailed structure-property relationships in phthalocyanine compounds is useful for exploring the function of molecular aggregates in energy migration of natural photosynthesis systems.

Ultrafast Investigation of Intramolecular Charge Transfer and Solvation Dynamics of Tetrahydro[5]-helicene-Based Imide Derivatives

“…The femtosecond transient absorption investigations were performed at ~90 fs time resolution using a home-built femtosecond broadband pump-probe setup described in detail elsewhere 42 55 56 . The absorbance of the solutions was around 0.25 OD at 400 nm in a 1 mm thick quartz cuvette.…”

Intramolecular Charge Transfer and Solvation of Photoactive Molecules with Conjugated Push–Pull Structures

“…The femtosecond time‐resolved TA measurements were performed using an in‐house‐built femtosecond broadband pump–probe setup described in detail elsewhere . In brief, the 400 nm excitation pulses were produced by second‐harmonic generation of the 800 nm fundamental output of a regeneratively amplified Ti:sapphire laser (Coherent Legend Elite, 40 fs, 1 mJ, 500 Hz, full width at half‐maximum: 30 nm).…”

“…The femtosecond time-resolved TA measurements were performed using an in-house-built femtosecond broadband pump-probe setup described in detail elsewhere. [41,49] In brief, the 400 nm excitation pulses were produced by second-harmonic generation of the 800 nm fundamental output of ar egeneratively amplified Ti :sapphire laser (Coherent Legend Elite, 40 fs, 1mJ, 500 Hz, full width at half-maximum:3 0nm). The white-light continuum generated by focusing the 800 nm pulse on aw ater cell was used as the probe beam, which was split into signal and reference beams before arriving the sample.…”

Advances in Metal Phthalocyanine based Carbon Composites for Electrocatalytic CO2 Reduction

“…Metal phthalocyanine molecules have many advantages, such as easy availability, high chemical stability, and adjustable structure. [27][28][29][30][31][32][33][34][35][36][37][38][39][40] Recently, some researchers combined metal phthalocyanine complexes with carbon nanotubes and graphene materials in different ways to form a new catalytic composite, which contains efficient catalytic properties and catalytic potential, thus breaking the potential energy barrier of carbon dioxide in the electrocatalytic process (Table 2). For example, the current catalytic products are usually carbon monoxide, formate, oxalate, [41][42] but after catalyzed by composite materials, more favorable catalytic products (methanol and other chemical value-added products) can be obtained, [43] which accelerates the broader market application prospects of catalytic composite materials.…”