The photodynamic therapy of cancer is contingent upon the sustained generation of singlet oxygen in the tumor region. However, tumors of the most metastatic cancer types develop a region of severe hypoxia, which puts them beyond the reach of most therapeutic protocols. More troublesome, photodynamic action generates acute hypoxia as the process itself diminishes cellular oxygen reserves, which makes it a self-limiting method. Herein, we describe a new concept that could eventually lead to a change in the 100 year old paradigm of photodynamic therapy and potentially offer solutions to some of the lingering problems. When gold nanorods with tethered endoperoxides are irradiated at 808 nm, the endoperoxides undergo thermal cycloreversion, resulting in the generation of singlet oxygen. We demonstrate that the amount of singlet oxygen produced in this way is sufficient for triggering apoptosis in cell cultures.

Versatile BODIPY dyes can be transformed into bright near-IR-emitting fluorophores by quadruple styryl substitutions. When clickable functionalities on the styryl moieties are inserted, an efficient synthesis of a light harvester is possible. In addition, clear spectral evidence is presented showing that, in dendritic light harvesters, calculations commonly based on quantum yield or emission lifetime changes of the donor are bound to yield large overestimations of energy transfer efficiency.Efficient harvesting of solar radiation requires judiciously designed absorbers. Considering the fact that it would be difficult to have a single molecule with strong absorptions in the entire visible spectrum and near-IR (perfect black dye), it makes more sense to seek multichromophoric dye ensembles. Different chromophoric units can be brought together either by covalent bonds or by noncovalent interactions. In either case, excitation energy transfer (EET) from the donor chromophores (shorter wavelength absorption) to the acceptor (longer wavelength absorbing core) module is expected. The efficiency of energy transfer from the antenna chromophores to the central core is very important. In such multichromophoric light harvesters, energy transfer can be either through-space 1 or through-bond. 2 Through-space energy transfer is also possible between two or more free chromophoric units. This kind of energy transfer has been thoroughly studied, and in fact, the F€ orster (throughspace) energy transfer model is built on the interaction of such transition dipole coupled chromophoric pairs. Three important parameters determine the efficiency of energy transfer: donorÀacceptor distance, relative orientations of the transition dipoles, and the spectral overlap between the relevant absorption and emission bands. In proteins, either utilizing endogenous fluorescence of tryptophan or using fluorescent labels, EET efficiency calculations based on quantum yield or lifetime changes have been successful, but proteins are large and flexible enough for orientation of the dipoles to be averaged, and typically, reference fluorophores are in the same microenvironment. This simplified energy transfer calculation approach was later carried out on covalently linked multichromophoric light harvesters. In these energy transfer cassettes, energy funnels, or dendritic light harvesters, energy transfer efficiency is calculated assuming that the original bimolecular model can be directly related to an energy transfer process in a

Bright fluorescence of the BODIPY dyes, just like most other fluorophores, is quenched in the solid state due to reabsorption and selfquenching. However, introduction of bulky tert-butyl substituents on the meso-phenyl groups result in more spaced packing in the solid state, resulting in highly luminescent powders and films.