Carbon-rich acetylenic scaffolding: rods, rings and switches

Derivatives of tetraethynylethene (TEE, 3,4-diethynylhex-3-ene-1,5-diyne) a nd (E)-1,2-diethynylethene ((E)-DEE, (E)-hex-3-ene-1,5-diyne) provide a uni que class of pi -conjugated building blocks for modular construction of one - and two-dimensional carbon-rich scaffolds such as monodisperse, linearly pi -conjugated oligomers extending in length beyond 10 nm or large macrocyc lic all-carbon cores. Lateral functionalisation of these novel chromophores with donor-acceptor substituents strongly enhances their advanced material s properties and leads to exceptional third-order optical nonlinearities. N ew photochromic molecules were prepared which undergo photochemical cis --> trans and trans --> cis isomerisation without competing thermal isomerisat ion pathways, thereby paving the way for applications as light-driven molec ular switches in optoelectronic devices.