Photocontrol of Triple-Helix Formation by Using Azobenzene-Bearing Oligo(thymidine) This work was partially supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science, and Culture, Japan (Molecular Synchronization for the Design of New Material Systems). The grant from the "Research for the Future" program of the Japanese Society for the Promotion of Science (JSPS-RFTF97I00301) is also acknowledged.