Synthesis of Covalently Linked β‐ Meso ‐Phenyl Ethyne Bridged 14 π Triphyrin(2.1.1)–18 π Porphyrin(1.1.1.1) Dyads

ABSTRACT The first examples of covalently linked, β‐ meso ‐phenyl ethyne bridged dyads 1–6 containing 14 π triphyrin(2.1.1)/metallotriphyrin, and 18 π porphyrin/metalloporphyrin subunits were synthesized in decent yields. The free base 14 π triphyrin(2.1.1)–18 π porphyrin(1.1.1.1) dyad 1 was prepared by Sonogashira cross coupling of β‐monobromo triphyrin(2.1.1) 7 and 5‐[4‐ethynylphenyl]‐10,15,20‐tri( p ‐tolyl) porphyrin 8 in toluene/TEA at 40°C for 12 h. The triphyrin(2.1.1)–metalloporphyrin dyads 2 , 3 , and 4 were obtained by treating free base dyad 1 with NiCl 2 , CuCl 2 , and Zn(CH 3 COO) 2 salts, respectively, in CHCl 3 /CH 3 OH at reflux, whereas metallotriphyrin–metalloporphyrin dyads 5 and 6 were synthesized by reacting dyads 2 and 4 , respectively, with Re(CO) 5 Cl in toluene/TEA under refluxing conditions. Dyads 1–6 are very unique and contain two different types of aromatic conjugated macrocycles, such as contracted 14 π triphyrin(2.1.1) and regular 18 π porphyrin(1.1.1.1), having different properties. The absorption and the electrochemical studies supported weak interactions between the subunits in dyads 1–6 . The density functional theory (DFT) studies revealed that in dyads 1–6 , the triphyrin(2.1.1)/metallotriphyrin and porphyrin/metalloporphyrin units were oriented with a dihedral angle in the range of 24°–65° with respect to each other.