Photoactivation is a promising approach for modulating the biological activity of RuII compounds. In this work, RuII flavonolato compounds, [Ru(η6-p-cymene)(L)(3-Hfl)]OTf (8; 3-Hfl = monoanion of 3-hydroxyflavone; L = solvent) and [Ru(η6-p-cymene)Cl(3-Hfl-X)] (3a–3c; 3-Hfl-X = p-H, -Cl, or -F on the flavonolato phenyl substituent), have been evaluated for photoinduced reactivity within the flavonolato unit upon irradiation with UV (300 nm) or visible (419 nm) light under aerobic conditions. For each compound, irradiation in CH3CN was found to result in the loss of the p-cymene ligand and the formation of products resulting from oxidative ring opening of the flavonolato ligand in a dioxygenase-type reaction. This reaction also results in the release of carbon monoxide. The RuII products generated in these reactions are [RuII(solvent)(carboxylato)]+ and [Ru(CO)(solvent)(carboxylato)]+ (carboxylato = O-benzoylsalicylato or benzoato) species, as determined by ESI-MS. The amount of free CO generated depends on the wavelength of irradiation, with 300 nm light giving a higher amount of free CO. Evaluation of the photoinduced reactivity of 8 in DMSO/H2O (10:90) at 300 nm showed similar reactivity to that found in organic solvent, although the reaction occurs more slowly. The products of the photoreactions of 8 and 3a at 419 nm are nontoxic toward human T-lymphocyte (Jurkat) and non-small-cell lung carcinoma (A549) cells. This lack of toxicity versus the starting compounds is likely due to differences in interactions of the [RuII(solvent)(carboxylato)]+ and [RuII(CO)(solvent)(carboxylato)]+ species with biomolecules (e.g., serum proteins), thus resulting in reduced bioavailabilty. 1H NMR studies provide evidence that the photoreaction products coordinate to biologically relevant donors such as histidine and 5′-GMP in d 6-DMSO/D2O (10:90) and exhibit reactivity with these small molecules that is distinctly different from that exhibited by the starting compounds. Overall, the photoreactivity of 8 and 3a–3c may represent an approach toward altering the biological chemistry of these compounds.

Two poly(p-phenylenevinylene) derivative alternating copolymers (P1-I and P2-I) have been prepared featuring iodo substituents and m-phenylene units to periodically disrupt conjugation. P1-I was derivatized with various chromophores to yield P1a-f. In P1a-f, the chromophores were positioned within a sterically protected pocket shielding them from interchain interactions so that intrachain interactions between polymer segments could be observed. Solution and film properties of polymers have been examined. Post-polymerization chromophore modification leads to new photophysical properties such as intramolecular charge transfer and fluorescent resonance energy transfer processes in some cases.

Three phosphonium polyelectrolytes have been prepared wherein the flexibility of the spacer between charge‐bearing phosphonium units was varied from 1,2‐ethyl to 1,4‐phenyl to 1,1′‐ferrocenyl. The influence of inter‐phosphonium spacer flexibility on the ability of the polyelectrolyte to form ordered films via layer‐by‐layer supramolecular assembly with anionic polythiophene and anionic poly(p‐phenylenevinylene) derivatives was also assessed through a combination of UV−visible spectroscopy and atomic force microscopy. The more flexible ionic polymers were found to be capable of forming thicker films and to maintain growth linearity up to at least 800 bilayers in some cases. © 2015 Society of Chemical Industry

A series of eight poly(p‐phenylene vinylene) (PPV) and poly(p‐phenylene ethynylene) (PPE) (P1–P8) derivatives were tested for their ability to detect the nitroaromatic explosive 2,4,6‐trinitrotoluene (TNT) and its model compound 2,6‐dinitrotoluene (DNT). The polymers P1–P8 represent five structural classes that have not been examined for nitroaromatic sensing. These new motifs include PPE derivatives with a main‐chain m‐terphenyl unit (P1) or oxacyclophane canopy‐like structure (P2) and PPV derivatives with 2,6‐mesitylenephenylene repeats (P3 and P4), 9,9‐dialkyl‐1,4‐fluorenylene repeats (P5 and P6), or m‐phenylene units that periodically disrupt π‐conjugation along the backbone of the polymer (P7 and P8). The time‐dependent photoluminescent response of films to TNT and DNT and the solution‐phase Stern‐Volmer quenching constants for both TNT and DNT were determined. The results are rationalized in terms of side‐chain sterics and π‐system electronics and are discussed relative to known conjugated polymers. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1487–1492

This work reports the preparation of a series of 2,2′-bipyridyl (bipy) modified π-conjugated polymers having an average of one or three monomer units (p-arylene ethynylene for PPE1 and PPE3 or 7,7dihexylfluorene for PF1 and PF3) between metal-binding sites. Spectroscopic data demonstrate that strategic placement of sterically encumbered mesityl groups about the metal binding sites enforces a 1:1 metal to bipy binding ratio. This steric coordination control ensures that the metalated polymers remain solution processable rather than forming insoluble networks via coordinative cross-linking. The solution photophysical and electrochemical properties of metal-free and metalated materials are reported and compared with those of related conjugated polymers and conducting metallopolymers.