Expanding\nthe Chemistry of Pentafluorophenyl-N-Confused\nPorphyrin: Diketonate Substitution and Derivatizations at the External\n3‑C Position of the Inverted Pyrrole Ring

In this study, we\nsynthesized two new 3-C-substituted pentafluorophenyl-N-confused\nporphyrins (PFNCPs), one with acetylacetonate (PFNCP-acac, <b>2a</b>) and the other with ylidene-2-propanone (PFNCP-ac, <b>3a</b>), through a one-pot reaction in the absence of a catalyst. Under\nmild acidic and heating conditions, the acac-substituted compound\nunderwent acyl cleavage degradation, yielding ac-substituted product <b>3a</b>. Subsequent chelation of the acac-substituted PFNCP with\nBF<sub>2</sub> resulted in a boron diketonate derivative, PFNCP-acacBF<sub>2</sub> (<b>4</b>). Additionally, an electrocyclic reaction\nof the ac-substituted PFNCP <b>3a</b>, without a catalyst, produced\na tricyclic fused [6,6,5]-TF-PFNCP (<b>5</b>). This tricyclic\nproduct could also be obtained directly from PFNCP-acac <b>2a</b> under heating conditions. The absorption spectra revealed that acac-\nand ac-substituted macrocycles exhibit either a single or split Soret\nband, respectively, in the 400–550 nm range, along with multiple <i>Q</i> bands spanning the 580–690 nm region. While BF<sub>2</sub> derivatization caused a slight red shift in the absorption\nspectra, the [6,6,5]-tricyclic fused NCP demonstrated a significant\nred shift. All newly synthesized compounds were characterized by using\nsingle-crystal X-ray structures, <sup>1</sup>H NMR spectroscopy, and\nmass spectrometry. Density functional theory (DFT) studies were conducted\nto elucidate the photophysical properties of these macrocycles.