1,4,7,10-tetraazacyclododecane, a macrocycle and the aza analogue of the crown ether 12-crown-4.

plural of cyclen

(organic chemistry) A cyclic hydrocarbon containing at least one double bond / (organic chemistry) 1,7,7-trimethyltricyclo[2.2.1.0^(2,6)]heptane also known as tricyclene