The photophysical and photobiological properties of a new class of cyclometalated ruthenium(II) compounds incorporating π-extended benzo[ h]imidazo[4,5- f]quinoline (IBQ) cyclometalating ligands (C^N) bearing thienyl rings ( n = 1-4, compounds 1-4) were investigated. Their octanol-water partition coefficients (log P) were positive and increased with n. Their absorption and emission energies were red-shifted substantially compared to the analogous Ru(II) diimine (N^N) complexes. They displayed C^N-based intraligand (IL) fluorescence and triplet excited-state absorption that shifted to longer wavelengths with increasing n and N^N-based metal-to-ligand charge transfer (MLCT) phosphorescence that was independent of n. Their photoluminescence lifetimes (τ) ranged from 4-10 ns for IL states and 12-18 ns forMLCT states. Transient absorption lifetimes (τ) were 5-8 μs with 355 nm excitation, ascribed to IL states that became inaccessible for 1-3 with 532 nm excitation (1-3, τ = 16-17 ns); the IL of 4 only was accessible by lower energy excitation, τ = 3.8 μs. Complex 4 was nontoxic (EC > 300 μM) to SK-MEL-28 melanoma cells and CCD1064-Sk normal skin fibroblasts in the dark, while 3 was selectively cytotoxic to melanoma (EC= 5.1 μM) only. Compounds 1 and 2 were selective for melanoma cells in the dark, with submicromolar potencies (EC = 350-500 nM) and selectivity factors (SFs) around 50. The photocytotoxicities of compounds 1-4 toward melanoma cells were similar, but only compounds 3 and 4 displayed significant phototherapeutic indices (PIs; 3, 43; 4, >1100). The larger cytotoxicities for compounds 1 and 2 were attributed to increased cellular uptake and nuclear accumulation, and possibly related to the DNA-aggregating properties of all four compounds as demonstrated by cell-free gel mobility-shift assays. Together, these results demonstrate a new class of thiophene-containing Ru(II) cyclometalated compounds that contain both highly selective chemotherapeutic agents and extremely potent photocytotoxic agents.

A series of cationic heteroleptic iridium(III) complexes bearing tris-diimine ligands [Ir(phen) 2 (Rphen)] 3+ (R-phen = phenanthroline (1), 3,8-diphenylphenanthroline (2), 3,8dipyrenylphenanthroline (3), 3-phenylphenanthroline (4), 3-pyrenylphenanthroline (5), and 3,8diphenylethynylphenanthroline (6)) were synthesized and characterized. These complexes possessed phen ligand-localized 1 π,π* transitions below 300 nm, and charge transfer ( 1 CT) and/or 1 π,π* transitions between 300 and 520 nm. In 1, 2, 4, and 6, the low-energy bands were mixed 1 CT/ 1 π,π*. However, the increased π-donating ability of the pyrenyl substituent(s) in 3 and 5 split the low-energy bands into a pyrene-based 1 π,π* transition at 300-380 nm and an intraligand charge transfer ( 1 ILCT) transition at 380-520 nm. All complexes were emissive at room temperature in CH 3 CN, but the parentage of the emitting state varied depending on the R substituent(s). Complex 1 exhibited predominantly phen ligand-localized 3 π,π* emission mixed with metal-to-ligand charge transfer ( 3 MLCT) character, while the emission of 2, 4, and 6 was predominantly from the excited-state with 3 π,π*/ 3 ILCT/ 3 MLCT character. The emission from 3 and 5 was dominated by pyrene-based 3 π,π* states mixed with 3 ILCT character. The different natures of the lowest triplet excited states were also reflected by the different spectral features and *

The starting point for the revolution in catenane and rotaxane synthesis that occurred during the last part of the 20th century was the realization by Sauvage and co-workers that metalligand coordination geometries could fix molecular fragments in three-dimensional space such that they were predisposed to form mechanically interlocked architectures through macrocyclization or "stoppering" reactions.[1] Efficient synthetic methods to rotaxanes were subsequently developed based on four-(tetrahedral) [2] , five-(trigonal bipyramidal and square pyramidal) [3] and, most recently, six-coordinate (octahedral) [4] metal templates (Figure 1). [5] One of the benefits of using specific coordination motifs for such assemblies is that the resulting interlocked ligands often do not permit other metal geometries in their binding site, which can consequently be exploited either to lock a metal in an unusual geometry for its oxidation state [6] or to bring about large-amplitude "shuttling" of the ligand components. [3,7] Here we show that threedimensional interlocked architectures can also be assembled from two-dimensional coordination templates by using steric and electronic restrictions to direct the synthesis in the third

Three new bis(2,2'-bipyridine)-heteroleptic Ru(II) dyads incorporating thienyl groups (n = 1-3, compounds 1, 2 and 3, respectively) appended to 1,10-phenanthroline were synthesized and characterized to investigate the impact of n on the photophysical and photobiological properties within the series. All three complexes showed unstructured emission near 618 nm from a triplet metal-to-ligand charge transfer ( MLCT) state with a lifetime (τ ) of approximately 1 μs. Transient absorption measurements revealed an additional excited state that was nonemissive and long-lived (τ = 43 μs for 2 and 27 μs for 3), assigned as a triplet intraligand ( IL) state that was accessible only in 2 and 3. All three complexes were strong singlet oxygen ( O ) sensitizers, with quantum yields (Φ ) for 2 and 3 being the largest (74-78%), and all three were photocytotoxic to cancer cells with visible light activation in the order: 3 > 2 > 1. Cell-free DNA photodamage followed the same trend, where potency increased with decreasing IL energy. Compounds 2 and 3 also showed in vitro photobiological effects with red light (625 nm), where their molar absorptivities were<100 m cm . These findings highlight that Ru(II) dyads derived from α-oligothiophenes directly appended to 1,10-phenanthroline-namely 2 and 3-possess low-lying IL states that are highly photosensitizing, and they may therefore be of interest for photobiological applications such as photodynamic therapy (PDT).