The cycloaddition of trans -1,2-bis(4-pyridyl)ethylene is directed by resorcinol in the solid state. This solid-state reaction proceeds in the presence of UV light in 100% yield . [13] Cycloaddition of trans -1,2-bis(4-pyridyl)ethylene Reducing market barriers In March 2006, the University of California published a report by Dr. Michael P. Wilson and