page_title: Boron porphyrins
section_title: Non-central boron-porphyrin interactions
hierarchical_section_title: Boron porphyrins / Non-central boron-porphyrin interactions
caption_attribution_description: English: Chemical structure of Boron porphyrins johbrbr
context_page_description: Boron porphyrins are a variety of porphyrin, a common macrocycle used for photosensitization and metal trapping applications, that incorporate boron. The central four nitrogen atoms in a porphyrin macrocycle form a unique molecular pocket which is known to accommodate transition metals of various sizes and oxidation states. Due to the diversity of binding modes available to porphyrin, there is a growing interest in introducing other elements into this pocket.
  Boron in particular has been shown to prefer binding to porphyrin in a 2:1 stoichiometry, primarily due to its small atomic radius, but the Group XIII element will bind in a 1:1 ratio with corrole, a macromolecule with a structure similar to porphyrin but with a smaller N₄ pocket.
  Boron porphyrins are of interest because of the unique geometric environment to which both boron and porphyrin are subjected upon B-N₍₎ bond formation. These new geometric motifs lead to novel reactivity, one of the most surprising examples being sterically-induced reductive coupling. Possible applications for boron porphyrins include BNCT delivery agents and OLED devices.
context_section_description: Two examples of boron-containing compounds that have been linked to porphyrin are BODIPY and diketonate.
  The BODIPY chromophore acts as an antenna: it absorbs a broad range of UV-visible light, then emits at a wavelength compatible with porphyrin absorption, allowing for efficient energy transfer.
  This work has been extended to triads  and to porphyrins with various core transition metals, some displaying multiphoton excitation.
  On the other hand, when boron difluoride β-diketonate is used for an antenna, the emission-absorption overlap is small and little change in the porphyrin's optical properties is observed. Though this chromophore is preferable to BODIPY in certain applications, it is not an effective antenna for porphyrin.
caption: One example of a porphyrin-BODIPY chromophore.[11]
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