LAUSR

An asymmetric bis(dithienylethene-acetylide) ruthenium(II) complex trans-Ru(dppe)2(L1o)(L2o) (1oo) incorporating two different dithienylethene-acetylides (L1o and L2o) was designed to modulate multistate photochromism in view of the well separated ring-closing absorption bands between L1o and L2o. Upon irradiation with appropriate wavelengths of light, complex 1 undergoes stepwise photocyclization and selective photocycloreversion to afford four states (1oo, 1co, 1oc, and 1cc). As a contrast, symmetric complexes trans-Ru(dppe)2(L1o)2 (2oo) and trans-Ru(dppe)2(L2o)2 (3oo) with two identical dithienylethene-acetylides were synthesized, and the corresponding photochromic behavior was investigated. The photochromic properties of the oxidized species (1oo+/1co+/1oc+/1cc+, 2oo+/2co+/2cc+, and 3oo+/3co+/3cc+) were also investigated. The ring-closing absorption bands of one-electron oxidized species 1oo+, 2oo+, and 3oo+ show obvious blue shifts relative to those of 1oo, 2oo, and 3oo, respectively. The ring-closing absorption bands in both neutral and oxidized species grow progressively following oo → oc/co → cc and oo+ → oc+/co+ → cc+. As revealed by spectroscopic, electrochemical, and computational studies, complex 1 displays eight switchable states through stepwise photocyclization, selective cycloreversion, and a reversible redox process.