Stabilizing G-States In Centrosymmetric Tetrapyrroles: Two-Photon-Absorbing Porphyrins With Bright Phosphorescence

Abstract

Using time-dependent density functional theory (TDDFT) and sum-overstates (SOS) formalism, we predicted significant stabilization of 2P-active g-states in a compact fully symmetric porphyrin, in which all four pyrrolic fragments are fused with phathalimide residues via the β-carbon positions. The synthesis of a soluble, nonaggregating meso-unsubstituted tetraarylphthalimidoporphyrin (TAPIP) was then developed, and the spectroscopic measurements confirmed that a strongly 2P-active state in this porphyrin is stabilized below the B (Soret) state level. Single-crystal X-ray analysis revealed near-ideally planar geometry of the TAPIP macrocycle, while its tetra-meso-arylated analogue (meso-Ar4TAPIP) was found to be highly saddled. Consistent with these structural features, Pt meso-Ar4TAPIP phosphoresces rather weakly (φphos = 0.05 in DMF at 22 °C), while both Pt and Pd complexes of TAPIP are highly phosphorescent (φphos = 0.45 and 0.23, respectively). In addition PdTAPIP exhibits non-negligible thermally activated (E-type) delayed fluorescence (φfl(d) ∼ 0.012). Taken together, these photophysical properties make metal complexes of meso-unsubstituted tetaarylphthalimidoporphyrins the brightest 2P-absorbing phosphorescent chromophores known to date.

Publication Date

8-24-2017

Publication Title

Journal of Physical Chemistry A

Volume

121

Issue

33

Number of Pages

6243-6255

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1021/acs.jpca.7b04333

Socpus ID

85028362028 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/85028362028

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