The synthesis of a bithiophene-bridged 34π conjugated aromatic expanded porphycene 1 and a cyclopentabithiophene bridged 32π conjugated anti-aromatic expanded porphycene 2 by a McMurry coupling strategy is presented. Magnetic measurements and theoretical calculations reveal that both 1 and 2 exhibit an open-shell singlet ground state with significant radical character (y0=0.63 for 1; y0=0.68, y1=0.18 for 2; y0: diradical character, y1: tetraradical character) and a small singlet–triplet energy gap (ΔES-T=−3.25 kcal mol−1 for 1 and ΔES-T=−0.92 kcal mol−1 for 2). Despite the open-shell radical character, both compounds display exceptional stability under ambient air and light conditions owing to effective delocalization of unpaired electrons in the extended cyclic π-conjugation pathway.
Bibliographical noteFunding Information:
J.W. acknowledges financial support from the MOE Tier 3 program (MOE2014-T3-1-004). The work at Yonsei University was supported by the National Research Foundation of Korea (NRF) through a grant funded by Korean government (MEST) (No. 2016R1E1A1A01943379).
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