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A para-hydroxyphenyl substituted pyrenoimidazole and two of its decylated derivatives were synthesized and characterized by UV-Vis absorption and fluorescence spectroscopic analyses. These compounds show significant UV-Vis absorption and fluorescence spectral responses to environmental acidity and basicity, suggesting application as sensitive fluorescence probes for pH. Their molecular structures and crystal packing properties were examined by single-crystal X-ray diffraction (SCXRD) analysis. With the aid of Hirshfeld surface analysis, the roles of various noncovalent forces, including hydrogen bonding, π-stacking, and CH⋯π interactions, in the formation of supramolecular assemblies in the solid state were elucidated.

A series of π-conjugated phenyl-pyrenoimidazole (Py-Im) systems were synthesized through a one-pot condensation reaction between 4,5-pyrenedione and various benzaldehyde derivatives. The single cry...

The provision of Information, Advice and Guidance (IAG) for school pupils considering their next move after compulsory schooling is of great importance to them and their families. This study focuse...

This paper is a reflective and critical review of research relating to widening participation (WP) in higher education (HE). The motivation for undertaking this was the twentieth anniversary of the...

The issue of localization/delocalization of electron spin density in Metal-to-Ligand Charge Transfer (MLCT) excited states of [Ru(bpy) 3 ] 2+ (bpy = 2,2′-bipyridine) has been debated for almost four decades. Localization/delocalization of MLCT excited states specifically addresses the question regarding electron configuration in the excited state and whether the excited electron in the dπ 5 π ∗1 excited state was localized on one ligand, [Ru III (bpy)(bpy − )] 2+∗ , or delocalized over all three, [Ru III (bpy − 1/3 ) 3 ] 2+∗ . This contribution outlines the results of a detailed meta-analysis of available experimental data to delineate the factors that govern how the excited state electron density evolves over the time from excitation until final excited state equilibration. Given the nature of the analysis, a number of interwoven issues are discussed in this article. A cohesive evaluation of the existing data leads to a detailed mechanistic understanding of the events that accrue following excitation of [Ru(bpy) 3 ] 2+ . The results of the meta-analysis are both remarkably systematic and consistent with existing theories of dynamic processes.

A monomer-through-pentamer series of oligo(1,8-pyrenylene)s was synthesized using a two-step iterative synthetic strategy. The trimer, tetramer, and pentamer are mixtures of atropisomers that interconvert slowly at room temperature (as shown by variable-temperature NMR analysis). They are liquids well below room temperature, as indicated by POM, DSC and SWAXS analysis. These oligomers are highly fluorescent both in the liquid state and in dilute solution (λF,max = 444-457 nm, φF = 0.80) and an investigation of their photophysical properties demonstrated that delocalization plays a larger role in their excited states than it does in related pyrene-based oligomers.

Despite decades of investment in patient safety, unintentional patient harm remains a major challenge in the health care industry. Peer-to-peer assessment in the nuclear industry has been shown to reduce harm. The study team’s goal was to pilot and assess the feasibility of this approach in health care. The team developed tools and piloted a peer-to-peer assessment at 2 academic hospitals: Massachusetts General Hospital and Johns Hopkins Hospital. The assessment evaluated both the institutions’ organizational approach to quality and safety as well as their approach to reducing 2 specific areas of patient harm. Site visits were completed and consisted of semistructured interviews with institutional leaders and clinical staff as well as direct patient observations using audit tools. Reports with recommendations were well received and each institution has developed improvement plans. The study team believes that peer-to-peer assessment in health care has promise and warrants consideration for wider adoption.

Significance Concerted proton-coupled electron transfer (EPT) reactions in which both electrons and protons transfer in tandem are at the heart of many chemical and biological conversions including photosystem II. We report here the direct observation of absorption bands arising from photoEPT transitions, in this case, in H-bonded complexes between N -methyl-4,4′-bipyridinium cation and biologically relevant donors including tyrosine. The importance of these observations follows from the earlier experimental observations by Taube and coworkers on intervalence transfer in mixed-valence complexes. The observation of these photoEPT transitions and the appearance of reactive radical products also points to a possible, if inefficient, role in DNA photodamage and, possibly, in the formation of reactive oxygen intermediates.

Much of the research into higher education and its role in work-based learning (WBL), and especially in supporting undergraduate students on placements, has focussed on longer term internships and sandwich courses. Research has also focussed on subject areas that have traditionally been associated with the above; for example, Business, Health, and Engineering. By contrast, the aim of this study was to gather data from students on a much shorter period of placement, categorised as a ‘short project’ (Brennan & Little, 1996). Furthermore, the data recovered was from students studying within the social sciences paradigm, undertaking an undergraduate degree in Education Studies (not teacher education). The social sciences and humanities more generally have not been discussed to any great extent within the context of research on placement or work-based learning (see Smith, Clegg, Lawrence, & Todd, 2007); the subject of Education Studies is not covered at all by previous research. This paper considers the different ways practitioners might blend learning and support university students’ experiential and academic learning in this short project format. The results suggest that even a relatively short period of structured placement can be of significant benefit to students although for many respondents, face-to-face contact in the form of lectures and tutorials is still an important component of a blended approach to WBL.

Much of the research into higher education and its role in work-based learning, and especially in supporting undergraduate students on placements, has focused on longer-term internships and sandwich courses. Research has also concentrated on subject areas that have traditionally been associated with the above, for example business, health and engineering. By contrast, the aim of this study was to gather data from students on a much shorter period of placement categorised as a ‘short project’. In addition, the data recovered was from students studying within the social sciences paradigm, undertaking an undergraduate degree in education studies (not teacher training). The social sciences and humanities more generally have not been discussed to any great extent within the context of research on placement or work-based learning; the subject area of education studies is not covered by previous research. The results suggest that even a relatively short period of structured placement can be of significan...

Lung surfactant (LS), a lipid–protein mixture responsible for alveolar stability, is inhibited by serum proteins leaked into the lungs in disease. Interaction of bovine lipid extract surfactant (BLES), a clinical replacement lung surfactant, with serum protein fibrinogen (Fbg) was studied employing various structural and biophysical techniques in adsorbed films and bulk bilayer dispersions. Surface tension area isotherms of the adsorbed films revealed the suppression of interfacial activity of BLES by Fbg (adsorption and surface tension reduction). Fbg, predominantly associated with the fluid phase of BLES films, resulted in the aggregation of the gel lipid domains as evidenced by atomic force microscopy. BLES bilayer dispersion showed phase transition from a diffused gel to liquid–crystalline phase in the temperature range 10–35 °C as studied by differential scanning calorimetry (DSC). Fbg resulted in the shift of peak to a higher transition temperature for the maximal heat flow (T max) of BLES dispersions. Combined Raman and FTIR spectral studies of the BLES/Fbg dispersions revealed that Fbg altered the –CH2–, –CH3, and –PO4 − vibrational modes of the phospholipids present in BLES, suggesting the condensing and dehydrating effect of the protein on surfactant. Studies suggest that Fbg, by directly interacting with the gel lipids in LS in bulk dispersions, alter the packing of the films formed at the interface, and can be used as a specific model for lung disease.

This paper examines the ultrafast dynamics of the initial photoactivation step in a molecular assembly consisting of a chromophore (denoted [RuaII]2+) and a water-splitting catalyst (denoted [RubII]2+) anchored to TiO2. Photoexcitation of the chromophore is followed by rapid electron injection from the Ru(II) metal-to-ligand charge-transfer (MLCT) excited state. The injection process was followed via the decay of the bpy radical anion absorption at 375 nm. Injection is ∼95% efficient and exhibits multiple kinetic components with decay times ranging from

In 1974, the metal-to-ligand charge transfer (MLCT) excited state, [Ru(bpy)3]2+*, was shown to undergo electron transfer quenching by methylviologen dication (MV2+), inspiring a new approach to artificial photosynthesis based on molecules, molecular-level phenomena, and a “modular approach”. In the intervening years, application of synthesis, excited-state measurements, and theory to [Ru(bpy)3]2+* and its relatives has had an outsized impact on photochemistry and photophysics. They have provided a basis for exploring the energy gap law for nonradiative decay and the role of molecular vibrations and solvent and medium effects on excited-state properties. Much has been learned about light absorption, excited-state electronic and molecular structure, and excited-state dynamics on timescales from femtoseconds to milliseconds. Excited-state properties and reactivity have been exploited in the investigation of electron and energy transfer in solution, in molecular assemblies, and in derivatized polymers and oligoprolines. An integrated, hybrid approach to solar fuels, based on dye-sensitized photoelectrosynthesis cells (DSPECs), has emerged and is being actively investigated.

Purpose To develop a patient safety curriculum and evaluate its impact on medical students' safety knowledge, self-efficacy and system thinking. Methods This study reports on curriculum development and evaluation of a 3-day, clinically oriented patient safety intersession that was implemented at the Johns Hopkins School of Medicine in January 2011. Using simulation, skills demonstrations, small group exercises and case studies, this intersession focuses on improving students' teamwork and communication skills and system-based thinking while teaching on the causes of preventable harm and evidence-based strategies for harm prevention. One hundred and twenty students participated in this intersession as part of their required second year curriculum. A pre–post assessment of students' safety knowledge, self-efficacy in safety skills and system-based thinking was conducted. Student satisfaction data were also collected. Results Students' safety knowledge scores significantly improved (mean +19% points; 95% CI 17.0 to 21.6; p Conclusions The patient safety intersession resulted in increased knowledge, system-based thinking, and self-efficacy scores among students. Similar intersessions can be implemented at medical, nursing, pharmacy and other allied health schools separately or jointly as part of required school curricula. Further study of the long-term impact of such education on knowledge, skills, attitudes and behaviours of students is warranted.

Although tetrathiafulvalene (TTF) and its derivatives have been extensively studied as important organic electronic materials over the past half century, tetrathiafulvalene vinyl-ogues (TTFVs) still remain a relatively underdeveloped branch in the family of TTF derivatives. Our recent work has investigated the synthesis and characterization of a class of diphenyl-substituted TTFVs carrying alkynyl functionality. The unique conformational and redox properties of such TTFV derivatives along with the versatile chemistry enabled by acetylenic groups (e.g., metal-catalyzed coupling and click reactions) have led us to a variety of functional molecular architectures ranging from oligoynes, polymers, and molecular tweezers, to macrocycles. Property studies of these new TTFV-based molecular materials point to appealing applications in molecular electronics and optoelectronics.

Despite significant medical advances, cardiac surgery remains a high risk procedure. Sub-optimal work system design characteristics can contribute to the risks associated with cardiac surgery. However, hazards due to work system characteristics have not been identified in the cardiovascular operating room (CVOR) in sufficient detail to guide improvement efforts. The purpose of this study was to identify and categorize hazards (anything that has the potential to cause a preventable adverse patient safety event) in the CVOR. An interdisciplinary research team used prospective hazard identification methods including direct observations, contextual inquiry, and photographing to collect data in 5 hospitals for a total 22 cardiac surgeries. We performed thematic analysis of the qualitative data guided by a work system model. 60 categories of hazards such as practice variations, high workload, non-compliance with evidence-based guidelines, not including clinicians' in medical device purchasing decisions were found. Results indicated that hazards are common in cardiac surgery and should be eliminated or mitigated to improve patient safety. To improve patient safety in the CVOR, efforts should focus on creating a culture of safety, increasing compliance with evidence based infection control practices, improving communication and teamwork, and designing better tools and technologies through partnership among all stakeholders.

A concise, highly regioselective synthesis of 1,8-dibromo-4,5-dialkoxypyrenes has been developed and exploited in the synthesis of some 1,8-pyrenylene-ethynylene macrocycles. The (1)H NMR data and NICS calculations indicate that there is little or no macrocyclic ring current. Concentration-dependent UV-visible studies indicate no aggregation at low concentration, but 8b forms dimers with voids suitable for intercalation of small molecules in the solid state.

A new type of structurally defined H-shaped OPE/OPV co-oligomers (termed H-mers) functionalized with various donor and/or acceptor end groups was synthesized by iterative Sonogashira coupling and Horner–Wadsworth–Emmons (HWE) reactions. Electronic substitution effects on the H-mer backbone were investigated by UV–vis absorption and fluorescence spectroscopy. Some H-mers were found to show spectral responses upon binding to an acid (TFA) or transition metal ions, revealing the applicability of H-mers in the field of chromophore and fluorophore based chemosensors.

This paper analyses the experiences and perceptions of parents and carers with respect to children accessing a variety of leisure activities, as well as short breaks and respite care. The children in question have wide‐ranging needs and, for example, will be across the Autistic Spectrum Disorder (ASD). The findings are based upon focus group interviews with parents and carers. They reveal a wide range of experiences and emerging themes such as concerns about staff training, public attitudes, isolation, mainstream or specialist provision, transport and accessibility. In the light of the ‘hidden’ nature of such disabilities, the paper focuses upon three of the most consistent and important themes to emerge: a sense of isolation and lack of engagement, staff training and attitudes, and the tension between whether to engage in mainstream or special provision. The paper concludes that practitioners and statutory bodies should consider these barriers in more detail when developing inclusive practice that will e...

This paper is based on the findings of a research project commissioned by a public body in the English Midlands, UK. Telephone surveys, focus groups and individual interviews were the data collection methods. It focuses on the perceptions of 44 families on the barriers to accessing leisure services for disabled children. Although there are numerous advantages for accessing such services, the findings showed that the families had very few successful experiences with the current provision due to a number of structural barriers. Trust was perceived as crucial to access these services.

A new fluorescence chemosensor (3) made up of a biscrown-annulated TTFAQ receptor and two anthracene fluorophores was designed and synthesized. Its solid-state structure was disclosed by X-ray crystallographic analysis, while fluorescence titrations indicated a high sensitivity for large hard metal cations such as Ba(2+).

Forty 4-year-olds and 39 6-year-olds participated in a modified misinformation-effects paradigm. At time 1 they reviewed a story and some of the children were asked questions about it in either recall or recognition format. Three weeks later they were given misinformation about some of the story events. The following week they were asked the original questions. Two years later the procedure was repeated with a different story for 31 of the children. Although 4-year-olds overtly disagreed more times than the older children did when misinformation was initially presented, this resistance did not affect their accuracy or suggestibility scores. The 6-year-olds became more resistant to the suggestive effects of misinformation when they were given an immediate recall test or when given the opportunity to disagree with misinformation. Significant test–retest correlations occurred over a two year period for both story accuracy and one of the suggestibility scores.

The synthesis of a class of highly pi-extended tetrathiafulvalene derivatives (1a and 1b) was explored using Sonogashira macrocyclization as a key step. The solid-state structure of 1b was characterized by X-ray single crystallography, showing a substantially bent, S-shaped molecular backbone and an ordered packing geometry in a pi-alkyl-alkyl-pi stacking fashion. Electronic and redox properties of 1b were investigated by UV-vis absorption, fluorescence spectroscopy, and cyclic voltammetry.

The condensation of 1,2-bis(3-hydroxy-2-naphthyl)ethane and formaldehyde under basic conditions was successfully employed for the synthesis of two new large-ring n-homocalixnaphthalenes 5 and 6. The synthetic yields using a relatively larger reaction scale were higher than those obtained by the sulphur extrusion approach. O-Alkylation of these homocalixnaphthalenes afforded the corresponding hexa- and octa-O-ester derivatives 5a and 6a respectively. The new naphthalene-ring based macrocycle 5a demonstrated high extraction capability for K+ under the conditions studied. O -Ethoxycarbonylmethoxy esters of homocalix[ n ]naphthalenes: synthesis and recognition behaviour towards alkali cations Huu-Anh Tran, Muhammad Ashram, Shehadeh Mizyed, David W. Thompson and Paris E. Georghiou* The condensation of 1,2-bis(3-hydroxy-2-naphthyl)ethane and formaldehyde under basic conditions was successfully employed for the synthesis of two new large-ring n-homocalixnaphthalenes 5 and 6.

A series of cruciform-shaped phenyleneethynylene and phenylenevinylene hybrid oligomers was prepared via a sequence of Sonogashira reactions. Using an in situ ethynylation protocol, these oligomers were end-functionalized with bis(fullerenyl) groups at the termini of the oligomers. Spectroscopic and electrochemical properties of these novel bisfullerene triads were studied in detail by UV–vis, fluorescence, and cyclic voltammetric analyses, and the results of these investigations are reported.

Both native and organic monolayer protected nanometer-sized silver particles were used to metallize patterns printed on glass and polyimide substrates by commercial permanent ink marking pens. The metal particles were selectively fixed onto the inked patterns by direct physical contact; the particles did not adhere to the free substrate surface. The patterns were made highly conductive by sintering or by mechanical buffing. The procedure allows the fabrication of patterned electrical circuits with minimal effort and a resolution of approximately 0.3 mm.

The authors believe that as we move from viewing adverse event reporting system as punitive, and as the safety culture improves, reporting will likely increase. Voluntary incident reporting systems can be used to improve patient safety in the ICU by identifying broken or inadequate systems that lead to adverse events [26]. Voluntary external reporting systems such as the ICUSRS can be used to target errors and produce evidence-based best practice measures to improve patient safety in the ICU.

Estimations of equilibrium or association constant ( K ASSOC ) values reported by many other groups for the supramolecular complexation between [60]fullerene (‘C 60 ’) with different macrocyclic hosts, in solvents such as toluene or carbon disulfide, for example, is often conducted by UV–vis absorption and/or 1 H NMR spectroscopy. In this paper, the complexation behaviour of two calix[4]naphthalene hosts with C 60 in toluene and carbon disulfide has been re-examined, using both of these methods. An analysis is presented of the data newly obtained, in light of recent advances and understanding published by others of the limitations of, in particular, the absorption spectroscopic methods. The discussion presented is also intended to aid those who may be unfamiliar with the nuances and limitations of the analytic models involving C 60 supramolecular complexation. Also presented is a general mechanism for C 60 supramolecular complexation studies, which lay the groundwork for further experiments.

Highly reflective, surface-metalized, flexible polyimide films were prepared by the incorporation of a soluble silver-ion complex, (hexafluoroacetylacetonato)silver(I) (AgHFA), into dimethylacetamide solutions of poly(amic acid) prepared from 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane. The thermal curing of solution-cast silver(I)–poly(amic acid) films to 300°C led to cycloimidization of the amic acid with concomitant silver(I) reduction and the formation of a reflective, air-side-silvered surface at very low (2 wt % and 0.3 vol %) silver concentrations. The reflective surface evolved only when the cure temperature reached about 275°C, although X-ray diffraction showed metallic silver in the hybrid film by 200°C. After a maximum specular reflectivity greater than 80% was achieved for the 2 wt % silver film, the specular reflectivity diminished sharply with further heating at a constant temperature of 300°C. Incorporating the AgHFA complex into the soluble, fully imidized form of poly{(1,3-dihydro-1,3-dioxo-2H-isoindole-2,5-diyl)[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene](1,3-dihydro-1,3-dioxo-2H-isoindole-5,2-diyl)-1,4-phenyleneoxy-1,4-phenylene[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]-1,4-phenyleneoxy-1,4-phenylene} gave films that were 25% less reflective than those beginning with poly(amic acid). Though highly reflective, the films were not electrically conductive. The metalized membranes were thermally stable and maintained mechanical properties similar to those of the parent polyimide. Transmission electron microscopy revealed an air-side, near-surface layer of silver that was about 40 nm thick; the interior of the film had well-dispersed metal particles with diameters mostly less than 2 nm. The near-surface silver layer maintained its integrity because of physical entrapment of the metal nanoparticles beneath a thin layer of polyimide; that is, the practical adhesion of the metal layer was good. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2409–2418, 2007

A previous article (Southward and Thompson, Chem Mater 2004, 16, 2091) focused on the characterization of surface metallized palladium-BTDA/4,4′-ODA (3,3′,4,4′-benzophenone tetracarboxylic dianhydride-4,4′-oxydianiline) hybrid membranes formed by in situ reduction of Pd2+ to Pd○ during thermal imidization of the poly(amic acid) via the protocol of St. Clair et al. (J Am Chem Soc 1980, 102, 876). The present work extended the Pd-polyimide metallization synthesis to the BPDA/4,4′-ODA (3,3′,4,4′-biphenyltetracarboxylic dianhydride-4,4′-ODA) polymer. The effects of the Pd2+ ligand on the reductive metallization of BTDA/4,4′-ODA were also examined for the PdCl2(SMe2)2, PdBr2(SMe2)2, and Pd(CF3COO)2 complexes. The hybrid films were characterized by specular and diffuse reflectivity and by conductivity measurement. Maximum specular reflectivity was in the range of 35%–55%, and conductivity was in the range of 1–10 Ω/square. Scanning electron microscopy and transmission electron microscopy revealed that the initial Pd metal particles formed within the films were in the 3–8 nm range in size. These particles increased in size with irregular shapes at the surface as the metallic exterior emerged. A fraction of the nanometer-sized Pd particles remained uniformly distributed throughout the bulk of the film. The mechanism for the formation of a metallic surface required selective oxidative degradation of the polyimide at the polyimide–air interface. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2708–2716, 2006

Flat, quantum dot like arrays of closely spaced, electron rich metal centres are seen as attractive subunits for device capability at the molecular level. Mn(II)9 grids, formed by self-assembly processes using 'tritopic' pyridine-2,6-dihydrazone ligands, provide easy and pre-programmable routes to such systems, and have been shown to exhibit a number of potentially useful physical properties, which could be utilized to generate bi-stable molecular based states. Their ability to form surface monolayers, which can be mapped by STM techniques, bodes well for their possible integration into nanometer scale electronic components of the future. This report highlights some new Mn(II)9 grids, with functionalized ligand sites, that may provide suitable anchor points to surfaces and also be potential donor sites capable of further grid elaboration. Structures, magnetic properties, electrochemical properties, surface studies on HOPG (highly ordered pyrolytic graphite), including the imaging of individual metal ion sites in the grid using CITS (current imaging tunneling spectroscopy) are discussed, in addition to an analysis of the photophysics of a stable mixed oxidation state [Mn(III)4Mn(II)5] grid. The grid physical properties as a whole are assessed in the light of reasonable approaches to the use of such molecules as nanometer scale devices.

Highly reflective and surface conductive flexible polyimide films have been prepared by the incorporation of silver(I) acetate and 1,1,1-trifluoro-2,4-pentanedione or 1,1,1,5,5,5-hexafluoro-2,4-pentanedione into a dimethylacetamide solution of the poly(amic acid) formed from 3,3‘,4,4‘-biphenyltetracarboxylic dianhydride and 4,4‘-oxydianiline. Thermal curing of the silver(I)-containing poly(amic acid) leads to cycloimidization of the polyimide precursor with concomitant silver(I) reduction yielding reflective and conductive silvered surfaces with properties approaching those of the native metal. The metallized films usually exhibit mechanical and thermal properties close to that of the parent polyimide. Films were characterized by X-ray diffraction, transmission and scanning electron microscopy, and X-ray photoelectron spectroscopy.

We present here the synthesis, characterization, and flash photolysis study of [(F(8)TPP)Fe(II)(CO)(THF)] (1) [F(8)TPP = tetrakis(2,6-difluorophenyl)porphyrinate(2-)]. Complex 1 crystallizes from THF/heptane solvent system as a tris-THF solvate, [(F(8)TPP)Fe(II)(CO)(THF)].3THF (1.3THF), with ferrous ion in the porphyrin plane (C(61)H(52)F(8)FeN(4)O(5); a = 11.7908(2) A, b = 20.4453(2) A, c = 39.9423(3), alpha = 90 degrees, beta = 90 degrees, gamma = 90 degrees; orthorhombic, P2(1)2(1)2(1), Z = 8; Fe-N(4)(av) = 2.00 A; N-Fe-N (all) = 90.0 degrees ). This complex (as 1.THF) has also been characterized by (1)H NMR [six-coordinate, low-spin heme; CD(3)CN, RT, delta 8.82 (s, pyrrole-H, 8H), 7.89 (s, para-phenyl-H, 8H), 7.46 (s, meta-phenyl-H, 4H), 3.58 (s, THF, 8H), 1.73 (s, THF, 8H)], (2)H NMR (pyrrole-deuterated analogue) [(F(8)TPP-d(8))Fe(II)(CO)(THF)] [THF, RT, delta 8.78 ppm (s, pyrrole-D)], (13)C NMR (on (13)CO-enriched adduct) [THF-d(8), RT, delta 206.5 ppm; CD(2)Cl(2), RT, delta 206.1 ppm], UV-vis [THF, RT, lambda(max), 411 (Soret), 525 nm], and IR [293 K, solution, nu(CO) 1979 cm(-)(1) (THF), 1976 cm(-)(1) (acetone), 1982 cm(-)(1) (CH(3)CN)] spectroscopies. In order to more fully understand the intricacies of solvent-ligand binding (as compared to CO rebinding to the photolyzed heme), we have also synthesized the bis-THF adduct [(F(8)TPP)Fe(II)(THF)(2)]. Complex 2 also crystallizes from THF/heptane solvent system as a bis-THF solvate, [(F(8)TPP)Fe(II)(THF)(2)].2THF (2.2THF), with ferrous iron in the porphyrin plane (C(60)H(52)F(8)FeN(4)O(4); a = 21.3216(3) A, b = 12.1191(2) A, c = 21.0125(2) A, alpha = 90 degrees, beta = 105.3658(5) degrees, gamma = 90 degrees; monoclinic, C2/c, Z = 4; Fe-N(4)(av) = 2.07 A; N-Fe-N (all) = 90.0 degrees ). Further characterization of 2 includes UV-vis [THF, lambda(max), 421 (Soret), 542 nm] and (1)H NMR [six-coordinate, high spin heme; THF-d(8), RT, delta 56.7 (s, pyrrole-H, 8H), 8.38 (s, para-phenyl-H, 8H), 7.15 (s, meta-phenyl-H, 4H)] spectroscopies. Flash photolysis studies employing 1 were able to resolve the CO rebinding kinetics in both THF and cyclohexane solvents. In CO saturated THF [[CO] approximately 5 mM] and at [1] congruent with 5 microM, the conversion of [(F(8)TPP)Fe(II)(THF)(2)] (produced after photolytic displacement of CO) to [(F(8)TPP)Fe(II)(CO)(THF)] was monoexponential, with k(obs) = 1.6 (+/-0.2) x 10(4) s(-)(1). Reduction in [CO] by vigorous Ar purging gave k(obs) congruent with 10(3) s(-)(1) in cyclohexane. The study presented in this report lays the foundation for applying fast-time scale studies based on CO flash photolysis to the more complicated heterobimetallic heme/Cu systems.

Paired electron transfers (ET) induced by the absorption of two photons by synthetic dendrimers are observed in first-, second-, and third-generation dendrimers comprised of a viologen-like core and an array of naphthalene peripheral groups. Flash photolysis and transient absorption techniques show that the yield of photoinduced double ET depends on laser intensity in the two largest dendrimers, NBV2(+2) and NBV3(+2). Their photochemical behavior thus requires an unusual multiphoton kinetic scheme. These dendrimers constitute the first synthetic models capable of multiple electron redox events deriving from a defined molecular architecture, thus mimicking natural light-collecting antenna systems.

Tris(2,4-pentanedionato)lanthanide(III) polyhydrates were added as inorganic sol−gel precursors to DMAc solutions of the polyimides formed from 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride and 1,3-bis-(aminophenoxy)benzene, 6FDA/1,3(3)-APB and 6FDA/2,2-bis[4-(4-aminophenoxy]hexafluoropropane, 6FDA/4-BDAF. Thermal treatment of doped-resin films gave composite oxo-metal(III) nanocomposite membranes which were visually clear with lower linear coefficients of thermal expansion, increased moduli, and reduced solvent sensitivity. Glass transition temperatures and 10% weight loss temperatures in nitrogen were close to those of the parent polymers. Films were characterized by thermal, mechanical, X-ray, and transmission electron micrographic techniques.

Lung surfactant is a complex mixture of lipid and protein, responsible for alveolar stability, becomes dysfunctional due to alteration of its structure and function by leaked serum materials in disease. Serum proteins, cholesterol and low density lipoprotein (LDL) were studied with bovine lipid extract surfactant (BLES) using Langmuir films, and bilayer dispersions using Raman spectroscopy. While small amount of cholesterol (10 wt%) and LDL did not significantly affect the adsorption and surface tension lowering properties of BLES. However serum lipids, whole serum as well as higher amounts of cholesterol, and LDL dramatically altered the surface properties of BLES films, as well as gel-fluid structures formed in such films observed using atomic force microscopy (AFM). Raman-spectroscopic studies revealed that serum proteins, LDL and excess cholesterol had fluidizing effects on BLES bilayers dispersion, monitored from the changes in hydrocarbon vibrational modes during gel-fluid thermal phase transitions. This study clearly suggests that patho-physiological amounts of serum lipids (and not proteins) significantly alter the molecular arrangement of surfactant in films and bilayers, and can be used to model lung disease.

Highly reflective and surface conductive flexible polyimide films have been prepared by the incorporation of silver(I) acetate and 1,1,1-trifluoro-2,4-pentanedione into a dimethylacetamide solution of poly(amic acid), formed from 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride and 4,4′-oxydianiline. Thermal curing of the silver(I)-containing poly(amic acid) leads to cycloimidization of the polyimide precursor with concomitant silver(I) reduction yielding a reflective and conductive silvered surface with properties approaching those of the native metal. Ligand/anion effects on the metallization process resulted when using additional silver(I) compounds including: silver(I) nitrate; silver(I) tetrafluoroborate; (trifluoroacetato)silver(I); (hexafluoroacetylacetonato)silver(I); (trifluoroacetylacetonato)silver(I); and 1-(2-thienyl)-3,3,3(trifluoroacetonato)silver(I). Comparisons among these six silver(I) compounds as precursors for the surface metallization of BTDA/4,4′–ODA are discussed with regard to reflectivity, conductivity and surface morphology. The metallized films usually retain the essential mechanical properties and thermal properties of a parent film. Films were characterized by X-ray diffraction, transmission and scanning electron microscopy, tapping mode atomic force microscopy and X-ray photoelectron spectroscopy. Also, electrical conductivity, reflectivity, differential scanning calorimetric, thermal gravimetric and mechanical measurements were made on the metallized films.

The relaxation dynamics and product distribution resulting from the decay of high lying excited states generated via sequential two-photon capture by [Ru(bpy)3]2+ or electron capture by [Ru(bpy)3]3+ have been investigated by flash photolysis and pulse radiolysis techniques. In comparison to the decay dynamics for monophotonic excitation, dramatically different relaxation dynamics have been observed. High-power flash excitation yields both the lowest lying metal-to-ligand charge transfer (3MLCT) state and a new transient photoproduct associated with nonradiative decay through the photodissociative metal-centered (3dd) excited state/s. The photoproduct is postulated to be [RuII(bpy)2(η1-bpy)]2+ where the pendant pyridine has rotated to yield a transient that is stabilized by a π−bonded or a three-centered Ru−C−H agostic interaction.

Spectroscopic evidence is presented for different structural isomers of trans -[Ru(bpy) 2 (L 1 )(L 1 )] 2+ (L 1 or L 2 =4-Etpy ( 1 ), py-PTZ) in which bpy is planar or nonplanar compared to cis -[Ru(bpy) 2 (py) 2 ] 2+ or [Ru(bpy) 3 ] 2+ in which bpy is planar. The nonplanar form is dominant in the ground states in low temperature glasses. The two forms appear to be in a temperature dependent equilibrium in 4:1 (v/v) ethanol/methanol at higher temperatures. The nonplanar form is converted into the planar form in the MLCT excited state(s) of 1 .

Cuprous bis-phenanthroline compounds possess metal-to-ligand charge transfer, MLCT, excited states. Phenanthroline ligands coordinated to Cu(I) that are disubstituted in the 2- and 9-positions with alkyl or aryl groups, abbreviated CuI(phen′)2+, have long-lived excited states at room temperature. The parent CuI(phen)2+ compound is non-emissive under the same conditions with a short excited state lifetime, τ

The Ru(II) compounds Ru(bpy)2(ina)2(PF6)2, Ru(deeb)2(py)2(PF6)2, Ru(deeb)(bpy)2(PF6)2, and Ru(dcb)(bpy)2(PF6)2, where py is pyridine, bpy is 2,2‘-bipyridine, ina is isonicotinic acid, deeb is 4,4‘-(CO2Et)2-2,2‘-bipyridine, and dcb is 4,4‘-(CO2H)2-2,2‘-bipyridine, have been prepared, characterized, and anchored to colloidal ZrO2 and TiO2 thin films for excited state and interfacial electron-transfer studies. In neat acetonitrile at 22 ± 2 °C, Ru(bpy)2(ina)2(PF6)2 is photochemically unstable and nonemissive with a short excited-state lifetime, τ < 10 ns. When anchored to ZrO2, the lifetime of Ru(bpy)2(ina)2(PF6)2 increases to 60 ns at 22 ± 2 °C and is highly temperature dependent due to the population of a low-lying state(s) that are proposed to be ligand field (LF) state(s). The LF state(s) can be populated directly from hot vibrational excited states and from the thermally equilibrated metal-to-ligand charge-transfer excited state. On TiO2 the excited-state behavior of Ru(bpy)2(ina)2(PF6)2 is very similar...

The photophysical and photoelectrochemical properties of Ru(deeb)(bpy)2(PF6)2, where bpy is 2,2‘-bipyridine and deeb is 4,4‘-(COOEt)2-2,2‘-bipyridine, anchored to nanocrystalline TiO2 (anatase) or ZrO2 films are reported. In neat acetonitrile (or 0.1 M tetrabutylammonium perchlorate) long-lived metal-to-ligand charge transfer (MLCT) excited states are observed on both TiO2 and ZrO2. Addition of LiClO4 results in a red shift in the MLCT absorption and photoluminescence, PL, spectra on both TiO2 and ZrO2, and a concentration-dependent quenching of the PL intensity on TiO2. The Li+-induced spectroscopic changes were found to be reversible by varying the electrolyte composition. Time-resolved absorption measurements demonstrate that the presence of lithium cations increases the quantum yield for interfacial charge separation with no discernible influence on the rate of charge recombination. A second-order kinetic model quantified charge recombination transients. A model is proposed wherein Li+ ion adsorption ...

4‘-(Ferrocenyl)-2,2‘:6‘,2‘ ‘-terpyridine (Fctpy) and 4‘-(4-pyridyl)-2,2‘:6‘,2‘ ‘-terpyridine (pytpy) were prepared from the corresponding ferrocene- and pyridinecarboxaldehyle and 2-acetylpyridine using the Krohnke synthetic methodology. Metal complexes, [M(Fctpy)2](PF6)2 (M = Ru, Fe, Zn), [Ru(tpy)(Fctpy)](PF6)2 (tpy = 2,2‘:6‘,6‘ ‘-terpyridine), and [Ru(pytpy)2](PF6)2 were prepared and characterized. Cyclic voltammetric analysis indicated RuIII/II and ferrocenium/ferrocene redox couples near expected potentials (RuIII/II ∼1.3 V and ferrocenium/ferrocene ∼0.6 V vs Ag/AgCl). In addition to dominant πtpy → πtpy* UV absorptions near 240 and 280 nm and dπRu → πtpy* MLCT absorptions around 480 nm, the complexes [Ru(Fctpy)2](PF6)2 and [Ru(tpy)(Fctpy)](PF6)2 exhibit an unusual absorption band around 530 nm. Resonance Raman measurements indicate that this band is due to a 1[(d(π)Fc)6] → 1[(d(π)Fc)5(π*tpyRu)1] transition. For [Ru(Fctpy)2](PF6)2 and [Ru(tpy)(Fctpy)](PF6)2, excited-state emission and lifetime measure...

Highly reflective and surface conductive flexible polyimide films have been prepared by the incorporation of silver(I) acetate and 1,1,1-trifluoro-2,4-pentanedione into a dimethylacetamide solution of the poly(amic acid) formed from 3,3‘,4,4‘-benzophenone tetracarboxylic acid dianhydride and 4,4‘-oxydianiline. Thermal curing of the silver(I)-containing poly(amic acid) leads to cycloimidization of the polyimide precursor with concomitant silver(I) reduction, yielding a reflective and conductive silver surface approaching that of the native metal. The metalized films retain the essential mechanical and thermal properties of the parent film. Films were characterized by X-ray diffraction, transmission and scanning electron microscopy, tapping mode atomic force microscopy, X-ray photoelectron spectroscopy, and conductivity, reflectivity, thermal, and mechanical measurements.

Excitation of Ru(deeb)(bpy)22+, bis(2,2‘-bipyridine)(2,2‘-bipyridine-4,4‘-diethylester)ruthenium(II) hexafluorophosphate, bound to nanocrystalline TiO2 thin films and immersed in an acetonitrile bath at 25 °C under an argon atmosphere, results in the formation of a species, the transient spectral characteristics for which are, consistent with a metal-to-ligand charge transfer, MLCT, excited state. The spectrum decays by kinetics that are inconsistent with a simple first-order process. Modeling of the data as a function of irradiance has been accomplished assuming parallel unimolecular and bimolecular excited-state deactivation processes. The quantum yield for excited-state formation depends on the excitation irradiance, consistent with triplet−triplet annihilation processes that occur with k ≥ 1 × 108 s-1.