Ru(II) Oligothienyl Complexes with Fluorinated Ligands: Photophysical, Electrochemical, and Photobiological Properties.

A series of Ru(II) complexes incorporating two 4,4'-bis(trifluoromethyl)-2,2'-bipyridine (4,4'-btfmb) coligands and thienyl-appended imidazo[4,5-f][1,10]phenanthroline (IP-nT) ligands was characterized and assessed for phototherapy effects toward cancer cells. The [Ru(4,4'-btfmb)2(IP-nT)]2+ scaffold has greater overall redox activity compared to Ru(II) polypyridyl complexes such as [Ru(bpy)3]2+. Ru-1T-Ru-4T have additional oxidations due to the nT group and additional reductions due to the 4,4'-btfmb ligands. Ru-2T-Ru-4T also exhibit nT-based reductions. Ru-4T exhibits two oxidations and eight reductions within the potential window of -3 to +1.5 V. The lowest-lying triplets (T1) for Ru-0T-2T are metal-to-ligand charge-transfer (3MLCT) excited states with lifetimes around 1 µs, whereas T1 for Ru-3T-4T is longer-lived (∼20-24 µs) and of significant intraligand charge-transfer (3ILCT) character. Phototoxicity toward melanoma cells (SK-MEL-28) increases with n, with Ru-4T having a visible EC50 value as low as 9 nM and PI as large as 12,000. Ru-3T and Ru-4T retain some of this activity in hypoxia, where Ru-4T has a visible EC50 as low as 35 nM and PI as high as 2900. Activity over six biological replicates is consistent and within an order of magnitude. These results demonstrate the importance of lowest-lying 3ILCT states for phototoxicity and maintaining activity in hypoxia.

Ru(II) Phenanthroline-Based Oligothienyl Complexes as Phototherapy Agents.

Ru(II) polypyridyl complexes have gained widespread attention as photosensitizers for photodynamic therapy (PDT). Herein, we systematically investigate a series of the type [Ru(phen)2(IP-nT)]2+, featuring 1,10-phenanthroline (phen) coligands and imidazo[4,5-f][1,10]phenanthroline ligands tethered to n = 0-4 thiophene rings (IP-nT). The complexes were characterized and investigated for their electrochemical, spectroscopic, and (photo)biological properties. The electrochemical oxidation of the nT unit shifted by -350 mV as n = 1 → 4 (+920 mV for Ru-1T, +570 mV for Ru-4T); nT reductions were observed in complexes Ru-3T (-2530 mV) and Ru-4T (-2300 mV). Singlet oxygen quantum yields ranged from 0.53 to 0.88, with Ru-3T and Ru-4T being equally efficient (∼0.88). Time-resolved absorption spectra of Ru-0T-1T were dominated by metal-to-ligand charge-transfer (3MLCT) states (τTA = 0.40-0.85 µs), but long-lived intraligand charge-transfer (3ILCT) states were observed in Ru-2T-4T (τTA = 25-148 µs). The 3ILCT energies of Ru-3T and Ru-4T were computed to be 1.6 and 1.4 eV, respectively. The phototherapeutic efficacy against melanoma cells (SK-MEL-28) under broad-band visible light (400-700 nm) increases as n = 0 → 4: Ru-0T was inactive up to 300 µM, Ru-1T-2T were moderately active (EC50 ∼ 600 nM, PI = 200), and Ru-3T (EC50 = 57 nM, PI > 1100) and Ru-4T (EC50 = 740 pM, PI = 114,000) were the most phototoxic. The activity diminishes with longer wavelengths of light and is completely suppressed for all complexes except Ru-3T and Ru-4T in hypoxia. Ru-4T is the more potent and robust PS in 1% O2 over seven biological replicates (avg EC50 = 1.3 µM, avg PI = 985). Ru-3T exhibited hypoxic activity in five of seven replicates, underscoring the need for biological replicates in compound evaluation. Singlet oxygen sensitization is likely responsible for phototoxic effects of the compounds in normoxia, but the presence of redox-active excited states may facilitate additional photoactive pathways for complexes with three or more thienyl groups. The 3ILCT state with its extended lifetime (30-40× longer than the 3MLCT state for Ru-3T and Ru-4T) implicates its predominant role in photocytotoxicity.

Tuning Interfacial Chemistry to Direct the Electrosynthesis of Metal Oxide Semiconductors.

ConspectusMetal oxide semiconductors have many features that make them attractive for both fundamental and applied studies. For example, these compounds contain elements (e.g., Fe, Cu, Ti, etc.) that are derived from minerals rendering them earth-abundant and, most often, are also not toxic. Therefore, they have been examined for possible applicability in a very diverse range of technological applications including photovoltaic solar cells, charge storage devices, displays, smart windows, touch screens, etc. The fact that metal oxide semiconductors have both n- and p-type conductivity makes them amenable for use as hetero- or homojunctions in microelectronic devices and as photoelectrodes in solar water-splitting devices. This Account presents a review of collaborative research on the electrosynthesis of metal oxides from our respective groups against the backdrop of key developments on this topic. The many variants that interfacial chemical modification schemes offer are shown herein to lead to the targeted synthesis of a wide array of not only simple binary metal oxides but also more complex chemistries involving multinary compound semiconductors and alloys.This Account presents our perspective on how parallel developments in the understanding of and ability to manipulate electrode-electrolyte interfaces have correspondingly enabled the innovation of a broad array of electrosynthetic strategies. These coupled with the advent of versatile tools to probe interfacial processes (undoubtedly, a child of the nanotechnology "revolution") afford an operando examination of how effective the strategies are to secure the targeted metal oxide product as well as the mechanistic nuances. Flow electrosynthesis, for example, removes many of the complications accruing from the accumulation of interfering side products─veritably, this is an Achilles heel of the electrosynthesis approach. Coupling flow electrosynthesis with downstream analysis tools based on spectroscopic or electroanalytical probes opens up the possibility of immediate process feedback and optimization. The combination of electrosynthesis, stripping voltammetry, and electrochemical quartz crystal nanogravimetry (EQCN), either in a static or in a dynamic (flow) platform, is shown below to offer intriguing possibilities for metal oxide electrosynthesis. While many of the examples below are based on our current and recent research and in other laboratories, unlocking even more potential will hinge on future refinements and innovations that surely are around the corner.

Electrodeposition of Silver Vanadate Films: A Tale of Two Polymorphs.

Two polymorphs of AgVO3 , namely the α- and ß- forms, were prepared and their physical, structural, optical, electrochemical, and photoelectrochemical characteristics were compared using a battery of experimental and theoretical tools. A two-step method, previously developed in the our laboratory for the electrodeposition of inorganic semiconductor films, was applied to the electrosynthesis of silver vanadate (AgVO3 ) films on transparent, conducting oxide surfaces. In the first step, silver was cathodically deposited from a non-aqueous bath containing silver nitrate. In the second step, the silver film was anodically stripped in an aqueous medium containing ammonium metavanadate. The anodically generated silver ions at the interface underwent a precipitation reaction with the vanadate species to generate the desired product in situ. Each of these steps were mechanistically corroborated via the use of electrochemical quartz crystal microgravimetry, used in conjunction with voltammetry and coulometry. As-deposited films were crystalline and showed p-type semiconductor behavior. Theoretical insights are provided for the electronic origin of the αâ†’ß phase transformation in AgVO3 and the disparate optical band gaps of the two polymorphs. Finally, implications for the application of this material in solar cells are provided.

Percutaneous nephrolithotomy of staghorn renal stones in pediatric patients using adult-sized instrument.

INTRODUCTION: In this study, we aimed to evaluate the safety and efficacy of the percutaneous nephrolithotomy procedure performed with adult-sized instruments in pediatric cases with staghorn kidney stone. METHODS: We retrospectively evaluated the efficacy and safety of 94 percutaneous nephrolithotomy procedures performed during 15 years in a single center for 82 pediatric patients with staghorn calculi using adult-sized instruments (24-Fr nephroscope). Stone free status was defined as complete clearance of the stones or the presence of insignificant residual stones of <3 mm in diameter. RESULTS: The mean age was 108 ± 53 months (range, 14-180 months). There were 39 patients (48%) with complete staghorn stones and 43 cases (52%) with partial staghorn. We fulfilled 91.4% of operations through a single access. The stone free rate was 86.6% after one percutaneous nephrolithotomy session. In total, seven patients referred for shock wave lithotripsy and four cases were scheduled for the second percutaneous nephrolithotomy session. Fever occurred in 18 patients (21%) and bleeding requiring transfusion in four children (5%). Prolonged leakage from nephrostomy site requiring anesthesia for double J stent placement occurred in one patient. No grade IV or V Clavien complication occurred. CONCLUSION: The success rate and complications of percutaneous nephrolithotomy with adult-size instruments in pediatric patients are acceptable.