Magnesium Tetra(phenylethynyl)porphyrin: Stepwise Synthetic Route, Crystal Structures, and Longer Singlet Excited‐State Lifetime than Zinc Congener

Abstract

Magnesium tetra(arylethynyl)porphyrins (aryl=Ph or 4-CF C H ) were synthesized via 5,15-di(triisopropylsilylethynyl)-10,20-di(arylethynyl)porphyrin to ensure good solubility and high synthetic yields. Magnesium tetra(phenylethynyl)porphyrin was subjected to structural analyses and physico-chemical characterization. Single-crystal X-ray analysis revealed porous crystal structures featuring solvent molecules in their pores. From femtosecond transient absorption measurements we concluded that the singlet excited-state lifetime of magnesium tetra(phenylethynyl)porphyrin is with 7.4 ns substantially longer than that of its zinc congener with 2.8 ns; this is attributed to the lower atomic weight of magnesium compared with zinc.

Origin of Panchromaticity in Multichromophore–Tetrapyrrole Arrays

“…Such factors are also expected to underpin the panchromaticity observed in similar ethyne-linked chromophore–tetrapyrrole constructs. Chromophores having larger π systems than a phenyl group are necessary to elicit substantial panchromaticity. , A next challenge is to learn how to organize a collection of panchromatic arrays to achieve effective light-harvesting with even greater optical cross section. Although nontrivial, preparing such an organized architecture with isoenergetic chromophores may be less daunting than that for a cascade of numerous spectrally distinct chromophores.…”

A Blueprint for the Stabilization of Sub‐Valent Alkaline Earth Complexes**

“…To verify this, we turned our attention towards complexes featuring a square planar coordination geometry. Square planar Mg(II) porphyrin complexes are relatively common, owing to the rigid conformation of the ligand dictating the geometry around the metal center;[ 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 ] however, these species are not suitable for our molecular design because of the redox activity of porphyrins and their incompatibility with large AE metals. Besides constrained square planar porphyrin complexes, a square planar geometry is a very rare coordination mode for the AE metals owing to the lack of crystal field stabilization.…”

High-yielding Pd2(dba)3·C6H6-based four-fold Sonogashira coupling with selenophene-conjugated magnesium tetraethynylporphyrin for organic solar cells

“…We rst utilized a stepwise strategy to synthesize the intermediate Mg-TEP-H 4 (1, magnesium(II) 5,10,15,20-tetraethynylporphyrin) by our previously reported method. 30,61 The detailed synthesis procedure is shown in Scheme 1. Here, we also redesigned the synthetic route to Br-DPP-Th and Br-Se-DPP-Th by employing Suzuki coupling instead of Stille coupling to avoid toxic organotin reagents (Schemes 1 and S1 †).…”