This experimental and theoretical study illustrates how phosphaalkenes, which are isolobal to alkenes, can utilize a variety of external triggers for molecular switching. The E/Z isomerization of a truxene-based phosphaalkene, i. e. TruxC=P-Mes* (Mes*=2,4,6-tris-t-butyl-benzene), is accomplished by irradiation, metal coordination, or deprotonation of the truxene core. The reversible and quantitative Z/E double bond isomerization by gold(I) coordination/decoordination of the phosphorous lone pair represents a novel fuelling strategy for molecular switches.