Singlet–triplet energy gap in a cyclophane-based organic diradical with parallel exchange coupling pathwaysElectronic supplementary information (ESI) available: synthesis and characterisation data for 4; minimum conformation for diradical 1. See http://www.rsc.org/suppdata/cc/b0/b001273o/

Abstract

The novel cyclophane diradical 1 possesses a singlet ground state with a singlet–triplet energy gap (ΔE_ST) of −0.20 and −0.24 kcal mol⁻¹, as measured with SQUID magnetometry and EPR spectroscopy, respectively. This large ΔE_ST may in part be associated with the two parallel 3,3′-biphenyl exchange coupling pathways (ECPs).