Mapping the influence of ligand electronics on the spectroscopic and 1O2 sensitization characteristics of Pd(ii) biladiene complexes bearing phenyl–alkynyl groups at the 2- and 18-positions† Maxwell I. Martin,a Trong-Nhan Pham, a Kaytlin N. Ward,a Anthony T. Rice,a Phoebe R. Hertler,a Glenn P. A. Yap, a Philip H. Gilmartina and Joel Rosenthal *a Abstract Photodynamic therapy (PDT) is a promising treatment for certain cancers that proceeds via sensitization of ground state 3O2 to generate reactive 1O2.