Ru(II) polypyridine complexes: photophysics, photochemistry, eletrochemistry, and chemiluminescence

Photophysics, photochemistry and solar energy conversion with tris(bipyridyl)ruthenium(II) and its analogues

Electrogenerated chemiluminescence (also called electrochemiluminescence and abbreviated ECL) is the process whereby species generated at electrodes undergo high-energy electron-transfer reactions to form excited states that emit light. The first detailed ECL studies were described by Hercules and Bard et al. in the mid-1960s, although reports concerning light emission during electrolysis date back to the 1920s by Harvey. After about 40 years study, ECL has now become a very powerful analytical technique and been widely used in the areas of, for example, immunoassay, food and water testing, and biowarfare agent detection. ECL has also been successfully exploited as a detector of flow injection analysis (FIA), high-performance liquid chromatography (HPLC), capillary electrophoresis, and micro total analysis (μTAS). Figure 1 illustrates a time line of various events in the development of ECL. A literature survey using SciFinder Scholar reveals that more than 2000 journal articles, book chapters, and patents on various topics of ECL have been published. The overall number of publications, as shown in Figure 2, has increased exponentially over the past 20 years, of which 40–50% were biorelated. Similar amounts of ECL papers could be also found from the Thomson ISI Web of Science as well as † Telephone (601) 266 4716; fax (601) 266 6075; e-mail wujian.miao@ usm.edu. Wujian Miao received his undergraduate diploma in chemistry from Nantong University (Nantong, China) in 1982, his M.Sc. degree in analytical chemistry from Zhongshan University (Guangzhou, China, with Jinyuan Mo) in 1991, and his Ph.D. degree in electrochemistry from Monash University (Melbourne, Australia, with Alan M. Bond) in 2000. He then served as a Research Scientist in CSIRO (Melbourne, Australia), followed by a postdoctoral fellowship at the University of Texas at Austin with Allen J. Bard in 2001. Since 2004 he has served as an assistant professor of chemistry at the University of Southern Mississippi.

Electrogenerated Chemiluminescence and Its Biorelated Applications

After having reviewed some aspects of microfluidic system preparation in the first part (1), in this second part of the review we will cover a number of standard operations (namely: sample preparation, sample injection, sample manipulation, reaction, separation, and detection) as well as some biological applications of micro total analysis systems (namely: cell culture, polymerase chain reaction, DNA separation, DNA sequencing, and clinical diagnostics). As previously, we will include papers issued from different scientific journals as well as useful abstracts from three conference proceedings: MEMS, Transducers, and μTAS. In this second part, we do not include the period covered by the history section (1975-1997) from part 1 but try to cover the relevant examples of the literature published between January 1998 and March 2002. We briefly describe articles that struck us as needing special attention, while more “standard” papers are dutifully reported in groups of interest. An article might be included in more than one section, depending on the ideas developed in it.

Micro total analysis systems. 2. Analytical standard operations and applications.

A critical review of light-driven interfacial charge-transfer reactions of transition-metal compounds anchored to mesoporous, nanocrystalline TiO2 (anatase) thin films is described. The review highlights molecular insights into metal-to-ligand charge transfer (MLCT) excited states, mechanisms of interfacial charge separation, inter- and intra-molecular electron transfer, and interfacial charge-recombination processes that have been garnered through various spectroscopic and electrochemical techniques. The relevance of these processes to optimization of solar-energy-conversion efficiencies is discussed (483 references).

Photodriven heterogeneous charge transfer with transition-metal compounds anchored to TiO2 semiconductor surfaces

We report the results from a new pump/probe spectrometer for potential use in combustion diagnostics that employs asynchronous optical sampling. The instrument consists of two frequency-doubled mode-locked Nd:YAG lasers operating at slightly different repetition rates, synchronously pumping two dye lasers (rhodamine 6G) to generate the pump and probe beams. The spectral and temporal capabilities of the instrument are examined by obtaining a spectrum and an excited state decay of rhodamine B. The instrument response is shown to be proportional to pump power, probe power, and sample absorptance. Different frequency synthesizers and different modes of triggering are used to study their effect on signal stability.

Pump/probe method for fast analysis of visible spectral signatures utilizing asynchronous optical sampling

Luminescence of tris(2,2'-bipyridine)ruthenium(II) dichloride

Photostudies of 2,2'-bipyridine bis(triphenylphosphine)copper(1+), 1,10-phenanthroline bis(triphenylphosphine)copper(1+), and 2,9-dimethyl-1,10-phenanthroline bis(triphenylphosphine)copper(1+) in solution and in rigid, low-temperature glasses. Simultaneous multiple emissions from intraligand and charge-transfer states

Chemiluminescence from Reduction Reactions

We report the first results from a new pump/probe technique called asynchronous optical sampling (ASOPS). The method employs a mode-locked, frequency-doubled Nd: YAG laser operating at a repetition rate of 81.5970000 MHz as the pump laser, and a synchronously pumped dye laser (R6G) operating at a repetition rate of 81.5870000 MHz as the probe laser system. The 10-kHz beat frequency produces a repetitive relative phase walk-out of the pump and probe pulses which replaces the optical delay line used in conventional instruments. Studies of rhodamine B in methanol demonstrate that the instrument response is proportional to pump power, probe power, and sample absorptance. The fluorescence lifetime of 4 × 10−5 M rhodamine B is determined to be 2.3 ns.

Fred E. Lytle

Papers

Pump/probe method for fast analysis of visible spectral signatures utilizing asynchronous optical sampling

Luminescence of tris(2,2'-bipyridine)ruthenium(II) dichloride

Chemiluminescence from Reduction Reactions

Pump/probe spectroscopy by asynchronous optical sampling