Articoli di riviste sul tema "Ruthenium-based optically pure complexes"

Optically pure P-stereogenic monophosphorus ligands containing a heterocyclic substituent have been prepared. They have been coordinated to Ru-η⁶-arene moieties in which the ligands act as mono- or bidentate. The complexes catalyse asymmetric transfer hydrogenation reactions with up to 70% ee.

CODRu(h3methylallyl)2 is a versatile starting material for the preparation of a wide range of chiral bisphosphines ruthenium(II) complexes: (P*P)Ru(h3methylallyl)2 2, Ru[X4(P*P)2] 3, and cationic monohydride ruthenium complex 4. A facile synthesis of new C2 electron-rich chiral phosphines, bis(phosphetano)benzene 8 and 1,1¢bis(phosphetano)ferrocene 10 is presented. Dynamic kinetic resolution was used for efficient syntheses of key components of the hexahydroazepane core 16 of balanol and of optically pure Boc-(2S,3R,3S)-iso-dolaproïne 19. Catalyst 4 was used in asymmetric hydrogenation of 22 to give (+)-cis-methyl dihydrojasmonate in high enantioselectivity.

We have prepared a new bis(bipyridyl) ligand 1 based on a chiral 9,9´-spirobifluorene core in both enantiomerically pure forms. This ligand was found to undergo diastereoselective self-assembly to optically pure dinuclear coordination compounds upon coordination to copper(I) and silver(I) ions. Surprisingly, however, the resulting diastereomer was not found to be D2-symmetric which is usually found for similar bis(bidentate) ligands, but rather C2-symmetric with differently configurated metal centers.

In this work, organic–inorganic hybrids based on nanocrystalline indium oxide and ruthenium (II) heteroleptic complexes were used as sensitive materials for room temperature light-activated NO2 detection. In2O3 was obtained by chemical precipitation method and then annealed at three different temperatures (T = 300, 500, 700 °C) in order to investigate the influence of the microstructure of indium oxide on sensor characteristics of hybrid materials and on kinetics of the rise and fall of photoconductivity. The results of the X-ray phase analysis demonstrated that the obtained materials are single-phase with a cubic bixbyite structure. The Ru (II) heteroleptic complex, which was used as a photosensitizer, made it possible to shift the optical sensitivity range of the hybrids to the low energy region of the spectrum and to use a low-power LED (λmax = 470 nm) source for the photoactivation process. The sensor properties were investigated toward NO2 at sub-ppm range at room temperature. It was found that for pure oxides, the sensor signal correlates with a specific surface area, while for hybrid materials, both the sensor signal and photoresponse increase with increasing the matrix crystallinity. In this case, the main role is played by traps of nonequilibrium charge carriers, which are structural defects in the matrix.

Brice Bosnich, an Australian inorganic chemist, graduated from the University of Sydney and obtained his PhD at the Australian National University, Canberra. He then worked successively at University College London, the University of Toronto and the University of Chicago. He had an abiding interest in stereochemistry and its relationship with chemical reactivity, and in the chirality and optical activity of coordination and organometallic complexes, mainly those of the d-block elements. His early studies concerned the topological and conformational behaviour of classical coordination compounds, mainly of cobalt(III), and made extensive use of the technique of circular dichroism. He put this background to elegant use in perhaps his most distinctive work, namely, the design and synthesis of a C 2 -symmetric ditertiary phosphine, ( S , S )-chiraphos, the rhodium(I) complex [Rh{Ph 2 PCH(CH 3 )CH(CH 3 )PPh 2 }] + of which catalysed efficiently the homogeneous hydrogenation of prochiral enamides to amino acids in high optical purity. Bosnich traced the high enantioselectivity to the chiral array of P-phenyl substituents that is generated on coordination of ( S , S )-chiraphos. In principle, catalytic enantioselective synthesis represents a powerful and economic method of introducing chirality into the synthesis of biologically active molecules, which, since the thalidomide tragedy, are required to be marketed only in optically pure forms. Dissymmetric ligands similar to ( S , S )-chiraphos are now routinely employed in this type of synthesis. Bosnich developed several other enantioselective processes based on organo-transition metal chemistry. He also had several quasi-theoretical interests, including the possible use of circular dichroism to determine the absolute configuration of chiral metal complexes, and the development of a molecular mechanics force field for metallocenes. He maintained a strong interest in the properties of multimetallic proteins and devoted much effort to the construction of chiral binucleating ligands. During the 7–8 years before his retirement from the University of Chicago in 2006, he shifted his research to supramolecular recognition by suitably designed metal complexes.

Abstract: A large variety of metal-based chiral complexes have been developed in the past twenty five years that allow for the effective catalytic resolution of an impressive range of racemic compounds. After the initial discovery of Ti-catalyzed kinetic resolution of allylic alcohols by Sharpless and coworkers in the early eighties, a number of other transformations have emerged that may be used for catalytic resolution. Amongst them are the Ru-catalyzed hydrogenation, the Zr-catalyzed carbomagnesation, the Mn-catalyzed epoxidation, the Co-catalyzed epoxide hydrolysis, and the Ti-catalyzed reduction of C=N and C=0 bonds. Most recently, the Mo-catalyzed ring-closing metathesis has been utilized to catalytically resolve organic molecules in an efficient manner. This article provides a brief overview of these and other major developments in metal-catalyzed kinetic resolution; strengths and weaknesses of various methods are discussed, and different protocols that afford identical or similar optically pure or enriched compounds are compared. Where possible, the available mechanistic paradigms that affords a rationale as to the observed stereochemical outcomes are provided.

Second-harmonic generation in the solid state is restricted to materials that crystallize in non-centrosymmetric space groups. Unfortunately, the vast majority of solids crystallize in centrosymmetric space groups and are therefore SHG-inactive. The requirement for solid-state asymmetry is addressed in a new series of organic salts. The acid p-nitrophenylglycine, SHG-inactive due to its centrosymmetric (P1) packing, was coupled to six optically pure amines to form salts and (or) complexes that, by virtue of their chiral counterion, crystallized in non-centrosymmetric space groups. The 1064 nm output from a Nd:YAG laser produced 532 nm second-harmonic generation from each of the six salts, with three of the salts producing second-harmonic intensities at least an order of magnitude greater than that of our standard, urea. X-ray crystallographic analysis was carried out on five of the six salts, and an attempt was made to rationalize the second-harmonic intensity of each of these five salts based on the orientation of its molecular charge-transfer axis in the unit cell and on its chromophore density.Key words: second-harmonic generation, nonlinear optics, chiral organic salts, crystal structures.

2,2-Dimethyl-3-(2′-hydroxypropyl)-5-carboxy-Δ3 -1,4-thiazine (1) is a designed antibacterial agent. Based on an analysis of how penicillin complexes to and reacts with a model of a penicillin-binding protein, 1 contains a functional group (C=N) that can react with a serine hydroxyl group of the receptor according to the putative reaction Enz-OH + C = N → Enz-O-C-NH. Compound 1 also contains additional substituents that are designed to position the O-H and C=N groups relative to one another in the enzyme–substrate complex in a geometry that attempts to reproduce the optimum geometry of approach of two such reactants. A most important assumption is that this optimum geometry can be computed ab initio. In a first preparation of 1, (±)-5-methyl-4-hexene-2-ol (2) was converted to the lithium salt of (±)-2-mercapto-2-methyl-5-tert-butyldimethylsiloxy-3- hexanone (7), which was condensed with the N-tert-butoxycarbonyl-D- and L-serine-β-lactones (3). The synthesis was completed by deprotection with formic acid and cyclization in water. The R and S enantiomers of 2 have now been obtained, and the absolute configuration of the alcohol established, by reaction of the R- and S-propylene oxides with an organometallic reagent prepared from β,β-dimethylvinyl bromide. The R alcohol has also been secured by lipase-catalyzed transesterification with trifluoroethyl butyrate, and chemical hydrolysis of the trifluoroethyl ester. The R and S enantiomers of 2 were converted to the R and S enantiomers of 7, and these were condensed with the R and S enantiomers of 3 to yield each of the stereoisomers of the chemically unstable 1 in ca. 95% optically pure form. Antibacterial activity resides in the 5S,8R and 5S,8S isomers. These findings are shown to be consistent with the theoretical model. It is hoped that the stability of the lead structure 1 can be improved, to allow binding experiments with penicillin recognizing enzymes to proceed.

Stereoretentive olefin metathesis based on ruthenium dithiolate complexes has become a very active field of research within the past years. This unique catalyst class is able to kinetically produce both Z- and E-alkenes in high stereochemical purity (typically >95:5) starting from stereochemically pure Z- or E-alkenes. The aim of this tutorial review is to organize the reported information concerning ruthenium dithiolate catalysts in a logic manner, thus providing an "operators handbook" for chemists who wish to apply this methodology in synthesis.

As a basic study to search a molecular recognition site in electron transfer proteins, optically-active ruthenium complexes, [RuII/III(bcmaa)(bpy)] (BCMAA: N,Nbis( carboxymethyl)amino acid, BPY: 2,2’-bipyridine), were designed and prepared. The electron transfer reaction with cytochrome c553 (Alcaligenes xylosoxidans GIFU1051) was kinetically investigated, and its enantio-selectivity was detected. Based on the results of enantio-selective behavior for cytochrome c553, the local structure of molecular recognition site of cytochrome c553 was discussed.

Treating [Ru(PPh3)3Cl2] with the amine 2-picolylamine (Picam) ligand in a 1:1 molar ratio, the Ru(II) complex trans-Ru(PPh3)2(Picam)Cl2 (1) is obtained in methylene chloride and can be isolated as a pure solid compound. The single-crystal structure of 1 was determined by X-ray crystallography. The geometry at the Ru metal center is a distorted octahedral environment with a trans arrangement of the two chlorides. A trans effect of the bond lengths was observed within the structure. Similarly, treating [Ru(PPh3)3Cl2] with 1:1:1 molar ratios of 2-picolylamine (Picam) and 1,1′-bis(diphenylphosphine)ferrocene (DPPF) ligands yielded the Ru(II) complex trans-Ru(DPPF)(Picam)Cl2 (2). In identical conditions, the homogeneous hydrogen transfer catalytic reactivity of complexes 1 and 2 has been tested in a basic 2-propanol solution and they indicate different catalytic activity. It was discovered that monodentate and bidentate phosphine ligands of Ru(II) complexes, as well as cis- and trans-chloro configuration display different catalytic properties from our experimental data, in agreement with literature data. Based on DFT calculations, the relative molecular catalytic reactivity of all available experimental data is understood from the relative calculated molecular energy.

Two novel silica based terbium complexes (Tb(Bipy)3 and Tb(Tyr)3) were encapsulated into poly(N-isopropylacrylamide) and two hydrogels with intense green emission were developed. The variation of intensity changes by Tb(III) 5D4 → 7F5 transition indicated the gradual reduction tendency upon the increasing temperature. The declined luminescence behaviors of the two gels undergo the linear decay process (5~30°C). During lower critical solution temperature (33°C) stage, the emission responses significantly improved unexpectedly. Moreover, the terbium emissive species-loaded hydrogels exhibited much enhanced mechanical properties than pure gel.

C3N4 is an innovative material that has had huge success as a photocatalyst in recent years. More recently, it has been coupled to robust metal oxides to obtain more stable materials. This work is focused on the different synthesis techniques used to prepare bare C3N4 and combined C3N4/ZnO mixed systems. Different precursors, such as pure melamine and cyanuric acid-based supramolecular complexes, were employed for the preparation of the C3N4 material. Moreover, different solvents were also used, demonstrating that the use of water leads to the formation of a more stable heterojunction. Structural (XRD), morphological (FESEM) and optical (UV-vis) measurements underlined the role of the precursors used in the preparation of the materials. A clear trend can be extrapolated from this experimental approach involving different intimate contacts between the two C3N4 and ZnO phases, strictly connected to the particular preparation method adopted. The use of the supramolecular complexes for the preparation of C3N4 leads to a tighter association between the two phases at the heterojunction, resulting in much higher visible light harvesting (connected to lower band gap values).

CZTS chalcopyrite semiconductor has received attention as a promising alternative as an absorber in thin-film solar cells because of the high absorption coefficient, direct bandgap (1.5 eV), nontoxic elements and sustained high electrical and optical properties. In the present work, CZTS thin film has been developed by the sol–gel spin coating method by thermal decomposition of metal ions and thiourea complexes under ambient environment. Annealing study of the above prepared CZTS thin films has been performed. The prepared CZTS samples were annealed at different temperatures 250 °C, 275 °C, 300 °C, and 325 °C respectively. Crystallographic structure, surface morphology, and optical properties were studied. XRD pattern shows the kesterite structure of the films with characteristics peaks for planes (112), (200), (220), and (312). Crystallite size, strain and dislocation densities were calculated. Sample annealed at 300 °C shows the most intense XRD peak and hence larger grain size. Grain size tends to increase as the annealing temperature increases up to 300 °C. At 325 °C SEM images show that cracks are formed in the film. At lower temperatures uniform, homogenous, smooth and densely packed films are formed. Raman spectroscopy is used to determine phase purity because many of binary and ternary chalcogenides show XRD peaks at similar positions to that of CZTS. A single peak at 336 cm–1 shows the pure kestrite phase of CZTS for all films.

The two achiral ligands tris(1-methyl-1H-imidazol-2-yl)methanol ((mim)3COH) and bis(1-methyl-1H-imidazol-2-yl)(3-methylpyridin-2-yl)methanol ((mim)2(mpy)COH) form on reaction with Fe(BF4)2∙6H2O, the octahedral low-spin complexes [Fe((mim)3COH)2](BF4)2∙MeCN (1) and [Fe((mim)2(mpy)COH)2](BF4)2∙0.5MeCN (2). Both octahedral complexes immediately rearrange to the chiral [Fe4O4]-cubane clusters [Fe4(mim)3CO)4](BF4)4 (3) and [Fe4(mim)3CO)4](BF4)4∙CHCl3 (4), whereas the highly symmetrical 3 crystallizes as racemate, 4 resolves based on the asymmetry introduced by the 2-methylpyridine moiety and crystallizes as an enantiomerically pure sample. Both clusters feature redox active [Fe4O4]-cubane cores with up to four individual accessible states, which directs towards a potential application as electron-shuttle.

Abstract. Over the last 40 years, the light use efficiency (LUE) model has become a popular approach for gross primary productivity (GPP) estimation in the carbon and remote sensing communities. Despite the fact that the LUE model provides a simple but effective way to approximate GPP at ecosystem to global scales from remote sensing data, when implemented in real GPP modelling, however, the practical form of the model can vary. By reviewing different forms of LUE model and their performances at ecosystem to global scales, we conclude that the relationships between LUE and optical vegetation active indicators (OVAIs, including vegetation indices and sun-induced chlorophyll fluorescence-based products) across time and space are key for understanding and applying the LUE model. In this work, the relationships between LUE and OVAIs are investigated at flux-tower scale, using both remotely sensed and simulated datasets. We find that i) LUE-OVAI relationships during the season are highly site-dependent, which is complexed by seasonal changes of leaf pigment concentration, canopy structure, radiation and Vcmax; ii) LUE tends to converge during peak growing season, which enables applying pure OVAI-based LUE models without specifically parameterizing LUE and iii) Chlorophyll-sensitive OVAIs, especially machine-learning-based SIF-like signal, exhibits a potential to represent spatial variability of LUE during the peak growing season.We also show the power of time-series model simulations to improve the understanding of LUE-OVAI relationships at seasonal scale.

ABSTRACT Tannins in forages complex with protein and reduce the availability of nitrogen to ruminants. Ruminal bacteria that ferment protein or peptides in the presence of tannins may benefit digestion of these diets. Bacteria from the rumina of sheep and goats fed Calliandra calothyrsus (3.6% N and 6% condensed tannin) were isolated on proteinaceous agar medium overlaid with either condensed (calliandra tannin) or hydrolyzable (tannic acid) tannin. Fifteen genotypes were identified, based on 16S ribosomal DNA-restriction fragment length polymorphism analysis, and all were proteolytic and fermented peptides to ammonia. Ten of the isolates grew to high optical density (OD) on carbohydrates (glucose, cellobiose, xylose, xylan, starch, and maltose), while the other isolates did not utilize or had low growth on these substrates. In pure culture, representative isolates were unable to ferment protein that was present in calliandra or had been complexed with tannin. One isolate, Lp1284, had high protease activity (80 U), a high specific growth rate (0.28), and a high rate of ammonia production (734 nmol/min/ml/OD unit) on Casamino Acids and Trypticase Peptone. Phylogenetic analysis of the 16S ribosomal DNA sequence showed that Lp1284 was related (97.6%) to Clostridium botulinum NCTC 7273. Purified plant protein and casein also supported growth of Lp1284 and were fermented to ammonia. This is the first report of a proteolytic, ammonia-hyperproducing bacterium from the rumen. In conclusion, a diverse group of proteolytic and peptidolytic bacteria were present in the rumen, but the isolates could not digest protein that was complexed with condensed tannin.

The 18th International Conference on Physical Organic Chemistry (ICPOC-18) took place at the Gromada Hotel in Warsaw, Poland on 20-25 August 2006 under the local auspices of Warsaw University and the Polish Chemical Society. It was organized by a local Organizing Committee from the Department of Chemistry of Warsaw University led by Prof. Tadeusz M. Krygowski.Although physical organic chemistry began in the 1930s and at the beginning was concerned mostly with the mechanisms and kinetics of organic reactions and their dependence on structural and medium effects, a great extension of the field toward bioorganic, organic, organometallic, theoretical, catalytic, supramolecular, and photochemistry has been observed for decades now. Representative topics for modern physical organic chemistry include: reaction mechanisms; reactive intermediates; bioprocesses; novel structures; reactivity relationships; solvent, substituent, isotope, and solid-state effects; long-lived charges; sextet or open-shell species; magnetic, nonlinear optical, and conducting molecules; and molecular recognition. Contributions from all of these fields were presented.About 220 researchers, representing 31 countries, participated in the conference. The following eight plenary lectures were presented:R. Huber (Nobel laureate, Germany): "Molecular machines in biology"A. Yonath (Israel): "The spectacular ribosomal architecture: Nascent proteins voyage towards folding via antibiotics binding-pockets"P. Coppens (USA): "Time-resolved diffraction studies of molecular excited states and beyond"K. S. Kim (South Korea): "De novo design based on nano-recognition: Functional molecules/materials and nanosensors/nanodevices"I. P. Beletskaya (Russia): "Mechanistic aspects and synthetic application of carbon-carbon and carbon-heteroatom bonds formation in substitution and addition reactions catalyzed by transition-metal complexes"S. Fukuzumi (Japan): "New development of electron-transfer catalytic systems"D. Braga (Italy): "Making crystals from crystals: A green route to crystal engineering and polymorphism"L. Latos-Grażyński (Poland): "Carbaporphyrinoids: Exploring metal ion-arene interaction in a macrocyclic environment"Additionally, 17 invited talks and, during two parallel sessions, 51 oral communications were presented. There were more than 100 poster presentations.I am pleased to introduce a representative selection of outstanding papers based on plenary and invited lectures delivered at ICPOC-18. In addition to the contributions mentioned above, this volume contains: a discussion of modern understanding of aromaticity (P. Fowler, UK); fascinating studies of new mechanisms focused on reactive intermediates (R. Moss, USA); interpretation of acidity, basicity, and hydride affinity by the trichotomy paradigm (Z. Maksić, Croatia); a quantum approach to proton transfer across hydrogen bond (F. Fillaux, France); a discussion of self-assembly of nickel(II) pseudorotaxene nanostructures on Au surface (R. Bilewicz, Poland); a discussion of synthesis and properties of macrocyclic receptors for anions (J. Jurczak, Poland); a description of novel organic-inorganic frameworks (J. Klinowski, UK); an application of microemulsions as microreactors (J. R. Leis, Spain); a discussion of silicon rehybridization and molecular rearrangements in hypercoordinate silicon dichelates (D. Kost, Israel); and a description of solvation in pure and mixed solvents (O. El Seoud, Brazil). All of these papers exemplify the broad range and diversity of interests of the participants and characterize the present and future challenges in physical organic chemistry.The social program of the conference included: a welcome reception; a Chopin music concert organized in cooperation with the Frederic Chopin Society; conference excursions, including Warsaw Old Town and Żelazowa Wola, the house where Chopin was born; the Warsaw Uprising (1944) Museum and the Heroes of Ghetto Memorial; and folk music dances during the conference dinner.Because ICPOC-18 was attended by quite a number of young chemists from all over the world, it can be expected that the next conference in this series, ICPOC-19, which will be held in July 2008 and is being organized by Profs. J. Ramon Leis from the University of Santiago de Compostela and A. Santaballa from the University of A Coruna (Spain), will not only reflect recent developments and the rich potential of physical organic chemistry, but will also demonstrate the aspirations of younger generations of scientists in this field.Krzysztof WoźniakConference Editor

Photochemistry is a mature science. A characteristic hallmark of a consolidated scientific discipline is that it increasingly broadens its scope of interests from an initial central core toward the periphery where it interacts with other areas. Most of the current scientific research is characterized by an enriching multidisciplinarity, focusing on topics that combine backgrounds from different fields. In this way, the largest advances are taking place at the interphase between areas where different fields meet.This multidisciplinarity is, I believe, also a characteristic feature of the current situation for photochemistry. Thus, photochemistry was initially focused on the understanding and rationalization at a molecular level of the events occurring after light absorption by simple organic compounds. Molecular organic photochemistry constituted the core of this discipline, and it largely benefited from advances in the understanding of the electronic states provided by quantum mechanics. Later, photochemistry started to grow toward areas such as photobiology, photoinduced electron transfer, supramolecular photochemistry, and photochemistry in heterogeneous media, always expanding its sphere of interest.This context of increasing diversity in topics and specialization is reflected in this issue of Pure and Applied Chemistry. The contributors correspond to some of the plenary plus two invited lectures of the XXth IUPAC Symposium that was held 17ñ22 July in Granada, Spain. The program included plenary and invited lectures and oral contributions grouped in 13 sections covering femtochemistry, photochemistry of biomacromolecules, single-molecule photochemistry, and computational methods in photochemistry to nanotechnology, among others. These workshop titles give an idea of the breadth of themes that were included in this symposium. While it is obvious that the list of contributions correspond to different subdisciplines in photochemistry, all of them have a common scientific framework to rationalize the facts.The purpose of the symposium was to present an overview of the current status of some research fronts in photochemistry. This issue begins with the 2004 Porter Medal Lecture awarded jointly by the Asian, European, and Interamerican Photochemical Societies that was given to Prof. Graham Fleming (University of California, Berkeley) for his continued advances in photosynthesis. Prof. Flemingís studies have constituted a significant contribution to the understanding of the interplay between the structure of photosynthetic centers of green plants and the mechanism of energy migration toward the photosynthetic centers. These events take place in a very short time scale and are governed by the spatial arrangement of the constituents.Continuing with photobiology, the second article by Prof. Jean Cadet (Grenoble University) describes the type of photochemical damage and photoproducts arising from DNA UV irradiation. Knowledge of these processes is important for a better understanding of skin cancer and the possibilities for DNA repair. Closely related with DNA damage occurring upon irradiation, the article by Prof. Tetsuro Majima (Osaka University) provides an account of his excellent work on photosensitized oneelectron oxidation of DNA.The concept of "conical intersection", developed initially by Robb and Bernardi to rationalize the relaxation of excited states, led to the foundation of computational photochemistry, which has proved to be of general application to photochemical reactions. In this issue, Prof. Massimo Olivucci (University of Siena) shows that quantum chemical calculations can also be applied to photochemical reactions occurring in photobiology and, in particular, to the problem of vision. These calculations are characterized by the large number of atoms that are included and the fact that they have to estimate at a high calculation level and with high accuracy the energy of states differring in a few kcal mol-1.The next article corresponds to one of the two invited lectures included in this issue. The one given by Dr. Virginie Lhiaubet-Vallet (Technical University of Valencia) in the workshop Photophysical and Photochemical Approaches in the Control of Toxic and Therapeutic Activity of Drugs describes the enantioselective quenching of chiral drug excited states by biomolecules. Moving from photobiology to free radical polymerization with application in microlithography, the article by Prof. Tito Scaiano (University of Ottawa) reports among other probes an extremely elegant approach to detect the intermediacy of radicals in photochemical reactions based on a silent fluorescent molecular probe containing a free nitroxyl radical.Solar energy storage is a recurrent topic and a long-desired application of photochemistry. In her comprehensive contribution, Prof. Ana Moore (Arizona State University) summarizes the continued seminal contribution of her group to the achievement of an efficient solar energy storage system based on the photochemical generation of long-lived charge-separated states. Another possibility of solar energy storage consists of water splitting. In his article, Prof. Haruo Inoue (Tokyo Metropolitan University) deals with artificial photosynthetic methods based on the use of ruthenium porphyrins as photosensitizers for the two-electron oxidation of water with formation of dioxygen.Also in applied photochemistry, Prof. Luisa De Cola (University of Amsterdam) reports on intramolecular energy transfer in dinuclear metal complexes having a meta-phenylene linker. The systems described by Prof. De Cola have potential application in the field of light-emitting diodes, since most of the complexes described exhibit electroluminescence. The second invited lecture is by Dr. Alberto Credi (University of Bologna), one of Europeís most promising young photochemists. In his interesting article, the operation upon light excitation of a rotaxane molecular machine is described. A macro-ring acting as electron donor moiety in a charge-transfer complex is threaded in a dumbbell-shaped component having two viologen units with different redox potential. Light absorption produces the cyclic movement of the macro-ring from one viologen station to the other.The last two contributions fall within the more classic organic photochemistry realm. Prof. Axel Griesbeck (University of Cologne) describes the multigram synthesis of antimalarial peroxides using singlet-oxygen photosensitizers adsorbed or bonded to polymer matrices. The last contribution comes from Prof. Heinz Roth (University of Rutgers), who has worked during his entire career in the fields of organic photochemistry and radical ion chemistry. Prof. Roth has summarized his vast knowledge in radical ion chemistry, reviewing the mechanism of triplet formation arising from radical ion pair recombination. This mechanism for triplet formation is currently gaining a renewed interest owing to the potential applicability to the development of phosphors.I hope that the present selection will be appealing and attractive for a broad audience of readers interested in photochemistry and will give readers an idea of the state of the art of some current topics in this area.Hermenegildo GarcíaConference Editor

A new fluorimetric and colorimetric dual-mode probe, 4-bromo-2-(hydrazonomethyl) phenol (BHP) has been synthesized and successfully utilized for the recognition of Cd2+/F‒ ions in DMSO/H2O (9:1, v/v) system. The probe displays dual channel of detection via fluorescence enhancement and colorimetric changes upon binding with F‒ and Cd2+ ions respectively. The Job’s plot analysis, ESI-MS studies, Density Functional Theoretical (DFT) calculations, 1H NMR and 19F NMR titration results were confirmed and highly supported the 1:1 binding stoichiometry of the probe was complexed with Cd2+/F‒ ions. Furthermore, intracellular detection of F‒ ions in HeLa cells and fluorescence imaging analysis in Zebrafish embryos results of the probe BHP might be used to reveal their potential applications in a biological living system. Introduction The quantification and detection of toxic metal ions in diverse fields have fascinated more attention in recent years due to their prominent and significant roles in clinical diagnosis and ecological system.1–6 Besides metal ions, anions also play an exclusive role in a variety of chemical and biological processes.7–12 In earlier, analytical methods for the detection of cations/anions has required highly sophisticated and expensive instruments such as atomic absorption spectrometry, inductively coupled plasma mass spectrometry, ion sensitive electrodes, and gas and ion chromatography. Amid, fluorescent techniques have more expedient in terms of rapidness, excellent sensitivity and selectivity, low cost, easy and feasible detection. In addition, optical detection mode analysis is a more appropriate method because of their potential features such as easy handling, real-time analysis and different signal output modes.13–16 Besides, colorimetric assays are more feasible and potent tool as they provide a simple visible authentication for analyte detection in the absence of instruments and tedious techniques. In this perspective, the recent research area has been mainly focused to design the novel multi-functional fluorometric and colorimetric sensors for the detection of ions in the different environments. Cadmium (Cd2+) is one of the important hazardous heavy transition metal ions17 in the environment due its carcinogenic nature. The higher accumulation of Cd2+ ion and inhalation of Cd-dust prompts more awful health issues in human like cancer, cardiovascular diseases, kidneys and liver damage.18 Furthermore, the Cd2+ ion has more advantages in several industries such as pigments in plastics, electroplating and batteries, etc. On the other hand, fluoride ions play an ample role in dental health and in the treatment of osteoporosis.19–22 The excess of fluoride ingestion prompted severe disease in human health like gastric and kidney problems.23 In some remote areas, the high level contamination of fluoride ions in drinking water triggered bone disease such as fluorosis.24–31 Thus, to develop and synthesize novel multifunctional probe for the detection and quantification of both cations and anions is a highly anticipated and imperative task. Scheme 1. Synthesis of probe BHP Herein, we have fabricated and synthesized a novel chromogenic and fluorogenic assay based on bromo substituted salicylhydrazone moiety for the colorimetric and fluorometric detection of F‒ ions and colorimetric detection of Cd2+ ions in DMSO/H2O (9:1, v/v) system. The UV-visible and fluorescence spectral analysis of BHP with Cd2+/F‒ ions exposed an outstanding ratiometric absorbance and colorimetric responses towards F‒ ions and also showed a visible colorimetric response towards Cd2+ ions. The fluorescence enhancement of BHP with F‒ ion was highly evaluated by DFT calculations. As well, the cell viability experimental results of BHP can be used for the detection of F‒ ions in both HeLa cells and Zebrafish embryos via high content analysis system. Experimental Methods 2.1 Materials All the chemicals used in the present study were in the analytical reagent grade and solvents used were of HPLC grade. Reagents were used as such received without any further purification. Metal ions such as K+, Na+, Ca2+, Mg2+, Fe2+, Fe3+, Ag+, Zn2+, Mn2+, Cu2+, Co2+, Ni2+, Cd2+, Al3+, Cr3+, Pb2+ and Hg2+ were purchased from Merck and S.D. Fine chemicals. The anions of Cl-, Br-, I-, SCN-, CN-, H2PO4-, HSO4-, NO3-, AcO- and F- were purchased as their tetrabutylammonium salts from Sigma–Aldrich Pvt. Ltd. Absorption measurements were performed on JASCO V-630 spectrophotometer in 1 cm path length quartz cuvette with a volume of 2 mL at room temperature. Fluorescence measurements were made on a JASCO and F- 4500 Hitachi Spectrofluorimeter with excitation slit set at 5.0 nm band pass and emission at 5.0 nm band pass in 1 cm ×1 cm quartz cell. 1H and 13C NMR spectra were obtained on a Bruker 300 MHz NMR instrument with TMS as internal reference using DMSO-d6 as solvent. Standard Bruker software was used throughout. 19F NMR spectra were recorded at 293K on BRUKER 400 MHz FT-NMR spectrometers using DMSO-d6 as solvent. ElectroSpray Ionisation Mass Spectrometry (ESI-MS) analysis was performed in the positive/negative ion mode on a liquid chromatography-ion trap mass spectrometer (LCQ Fleet, Thermo Fisher Instruments Limited, US). Fluorescence microscopic imaging measurements were determined using Operetta High Content Imaging System (PerkinElmer, US) 2.2. Synthesis of (E)-4-bromo-2-(hydrazonomethyl) phenol, BHP An absolute alcoholic solution (50 ml) of 5-bromosalicylaldehyde (0.5gm, 2.49 mmol) was refluxed under hydrazine hydrate (in excess) for 5 hr and the pale yellow color solid product was collected after recrystallized with ethanol and ethyl acetate mixture (yield, 95 %). 1H NMR (300 MHz, DMSO-d6) δ (ppm): 8.92 (s, 1H), 11.89 (s, 1H), 7.53 (d, J = 8.7 Hz, 1H), 6.94 (d, J = 5.8 Hz, 1H); 13C NMR (75 MHz, DMSO-d6) δ (ppm): 161.36, 158.51, 135.84, 131.82, 120.86, 119.69, 106.72. 2.3 Photophysical analysis of BHP The optical mode analysis of BHP towards various cations/anions in DMSO/H2O (9:1, v/v) system was carried out by using absorbance and fluorescence spectroscopy. UV-visible and fluorescence analysis of BHP with cations were gauged by using their corresponding acetate salts of metal ions. Tetrabutylammonium salts of competing anions were used for the anionic sensing analysis. 2.4 Computational Studies The optimized geometrical and ground state energy level calculations of BHP were obtained by Density functional theoretical (DFT) calculations were executed using Gaussian 09 program 32 with the 6-311G basis set. The optimized geometries and the fluorescence enhancement of probe BHP complexed with Cd2+/F- ions were attained by DFT-B3LYP level theory using 6-311G and LANL2DZ basis sets. 2.5 Cytotoxicity studies HeLa cell lines were procured from the National Center for Cell Science (NCCS), Pune, India. Cell lines are kept in the Dulbecco's Modified Eagle's medium (DMEM) supplemented with 10% fetal bovine serum (FBS), 1% antimycotic and antibiotic solution was used in this study. The cells were kept in an incubator at 25 °C with humidified atmosphere comprising 5% of CO2 and 95% of air. HeLa cells were loaded over the wells of 96 well-culture plates with a density of 1 x 104 cells/well. After 48 h of incubation, previous DMEM medium was exchanged with new medium and BHP (dissolved in DMSO) was added in the range of 0-200 µM to all the wells and further incubated over 3h. Cytotoxicity of BHP was measured by using MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. After incubation of HeLa cells with BHP, the medium was detached. Further, 100 μl of DMSO was added and the resulting formazan crystals were dissolved in DMSO. The cell viability was determined by measuring the absorbance of each well at 540-660 nm (formation of formazan) using a microplate reader. 2.6 In vivo fluorescence analysis in Zebrafish embryos The fluorescence imaging analysis was performed in four days old embryos. The embryos were seeded over F- ion alone for 2 h in the E3 medium. The E3 medium was prepared by dissolving 5.0 mM NaCl, 0.17mM KCl, 0.33mM CaCl2, 0.33mM MgSO4 ingredients in H2O (2L) and the pH 7.2 was adjusted by adding NaOH. The embryos were thoroughly washed with E3 medium. Successively, incubated embryos were sowed over 25 mM of BHP (in DMSO) solution for 3h. Further, embryos were washed again with E3 medium and fixed in 10% methyl cellulose solution for the good oriented images. The fluorescent images of BHP-F- were logged using high content screening microscopy. (Excitation wavelength of 482 nm and emission wavelength range of 500-700 nm). Results and discussion The probe, (E)-4-bromo-2-(hydrazonomethyl) phenol (BHP) has been synthesized by one step condensation between hydrazine and 5-bromosalicylaldehyde in ethanol (yield, 95 %) as shown in Scheme 1. The structure of the probe BHP was confirmed via 1H, 13C NMR analysis (Figure S1-S2, See ESI) 3.1. UV–vis spectral analysis of cations with BHP To investigate the cation sensing events of BHP towards different cations in DMSO/H2O (9:1, v/v) system by using UV-vis and fluorescence titration experiments. Initially, free probe BHP exhibited an absorption band at 367 nm and further addition of mono, di and trivalent cations such as Li+, K+, Ag+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Fe2+, Hg2+, Na+, Mg2+, Ca2+, Pb2+, Fe3+ and Cr3+ exhibited tiny changes in absorption spectr due to their weak interaction towards BHP except Cd2+ ion as shown in Figure 1. Interestingly, upon titrated with Cd2+ ion, a new absorption band appeared at 470 nm due to the highly resonance induced charge transfer ability of bromo substituted salicyl moiety while the solution turns into dark yellow color from pale yellow. Increasing addition of Cd2+ ion results gradual reduction of both higher and lower energy bands at 367 nm and 470 nm respectively as depicted in Figure 2. Figure 1. UV-vis spectra of BHP (10 µM) with different cations (5 × 10-3 M) in DMSO/H2O (9: 1, v/v) system. Figure 2. UV-vis spectra of BHP (10 µM) with Cd2+ (0 – 100 µM) in DMSO/H2O (9: 1, v/v) system Besides, fluorescence response of probe BHP towards various cations such as Li+, K+, Ag+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Fe2+, Hg2+, Na+, Mg2+, Ca2+, Pb2+, Fe3+ and Cr3+ including Cd2+ ion have been inspected in DMSO/H2O (9:1, v/v) system. Initially, the probe BHP displayed low intensed fluorescence band in free state. Addition of other commonly coexistent metal ions including Cd2+ ions exhibited trivial changes in fluorescence spectra. From these results, it is concluded that the probe BHP could serve as an excellent colorimetric assay for the detection of Cd2+ ions. 3.2. The sensing analysis of BHP towards anions Moreover, the anion binding attraction of BHP towards anions have been investigated in DMSO/H2O (9:1, v/v) system via both UV-visible and fluorescence spectral techniques. Initially the probe BHP showed the absorption band at 367 nm. Upon titrated with other anions such as Cl‒, Br‒, I‒, NO3‒, AcO‒, HSO4‒, H2PO4‒ and CN‒ were failed to alter the absorbance of the probe BHP except F‒ ions as shown in Figure 3a. Moreover, the incremental addition of F‒ ions (0-50 µM), the higher energy band at 367 nm was decreased along with the increment in new absorption band at 482 nm results an excellent ratiometric response. The new low energy band observed at 482 nm due to the deprotonation of–OH group present in salicyl moiety initiated by hydrogen bonding [Figure 3b]. At that affair, the solution turns into orange color from pale yellow and it was simply discerned by naked eye [Figure 4]. Besides, under identical condition, the fluorescence titration experiment of BHP was carried out in the presence of different anions. Interestingly, the probe BHP displayed low intensed fluorescence band at 601 nm and the other competing anions were failed to affect the fluorescence intensity except F‒ ions as shown in [Figure 5a]. Further, the incremental addition of F‒ ions triggers the enhancement in intensity results an excellent “turn on” fluorescence response due to the deprotonation and the inhibition of charge transfer state stimulated by resonance around the moiety [Figure 5b]. 3.3. Competitive experiments To gauge the selectivity and recognizing ability of BHP, competitive analysis was performed in the presence of varying concentration of F‒ ion (0-50 µM). Initially, the probe was treated with 5 × 10-3 M of different anions such as, CN-, I-, Br-, Cl-, NO2-, CH3COO-, H2PO4- and HSO4-. The other common competing anions were failed to bind with the probe BHP except F- ion [Figure 6 (a) and (b)]. From these observations, it is ensured that BHP could act as an excellent selective and sensitve chromogenic receptor for F- ions in real time monitoring and different biological applications. Figure 3 (a): UV-vis spectra of BHP with 5 × 10-3 M of other anions in DMSO/H2O (9: 1 v/v) system. (b) UV-visible spectra of BHP (5 µM) with F‒ (0-50 µM) in DMSO/H2O (9: 1 v/v) system. Figure 4. Naked eye detection of F‒ ions with BHP under visible light (top) and UV-lamp (bottom) and BHP with Cd2+ visible light only (bottom). Figure 5 (a): Fluorescence spectra of BHP (5µM) with 5 × 10-3 M of other anions in DMSO/H2O (9: 1, v/v) system. Excitation at 482 nm. Slit width is 5 nm. (b) Fluorescence spectra of BHP (5µM) with F‒ (0-50 µM) in DMSO/H2O (9: 1, v/v) system. Excitation at 482 nm. Slit width is 5 nm. Figure 6 (a): Selectivity analysis of F‒ ion with BHP in the presence of competing anions. Excitation at 480 nm, Slit width = 5 nm. (b) The blue bars represent the change of the fluorescence intensity of BHP with the consequent addition of other anions. The pink bars represent the addition of the competing anions to BHP. Excitation at 480 nm, Slit width = 5 nm. 3.4. Job’s plot analysis and calculation of binding constant of BHP for Cd2+/F‒ ions Furthermore, the Job’s plot [Figure 7(a) and (b)] analysis based on UV-visible and fluorescence titration experiments results confirmed the 1:1 binding stoichiometry of BHP with both Cd2+/F‒ ions respectively. To further support the binding stoichiometry of BHP with Cd2+/F‒ions, ESI-MS spectral analysis were performed. The ESI-MS spectral analysis of BHP-Cd2+/BHP-F‒ disclosed peaks at 327.45/258.28 corresponds to [BHP+Cd2++Na+]/[BHP+F‒+H++Na+] respectively (Figure S3-S4, See ESI). Furthermore, the 1:1 binding stoichiometry of BHP with F− ions was confirmed via 1H NMR titration profile (Figure 8) and 19F NMR. The deprotonation of ‒OH group present in the salicyl moiety was initiated by hydrogen bonding and the plausible binding mode of BHP with Cd2+ and F‒ ion is shown in Scheme 2. Further, the absorbance and fluorescence intensity changes of Cd2+ ions (A472 nm) and F‒ ions (A482 nm, I603 nm) were plotted against [Cd2+] and [F‒] respectively provided a good linear relationship between both BHP and Cd2+/F‒ ions (Figure S5, S6 and S7, See ESI). From absorbance and fluorescence titration profile, the binding constant values of BHP for Cd2+/F‒ ions were calculated using modified Benesi-Hildebrand method ions (Figure S8, S9 and S10, See ESI). The binding constant values of BHP with Cd2+ ions were found to be 4.26 ×10-4 M from UV-visible titration profile. Similarly, the binding constant values of BHP with F‒ ions were estimated to be 6.03 ×10-3 M / and 3.01 × 10-4 M from UV-visible and fluorescence titration profile respectively. The detection limits (LOD) of F‒ were calculated to be 0.05 nM respectively. Moreover, the LOD values of BHP signifies that the probe might be utilized for the quantitative determination of F‒ ions in environment and real system. Figure 7 (a) Job’s plot for BHP with F‒ ion. (b) Job’s plot for BHP with Cd2+ ion Scheme 2. Binding mode of BHP with Cd2+/F‒ ions 3.5. 1H NMR titrations of BHP with F- ions In addition, to confirm and highly supported the 1:1 binding stoichiometry of probe with F- ions, 1H NMR titrations was performed. Upon addition of F- ion (0.5 equiv), the proton signal corresponds to phenolic –OH group at 11.14 ppm was gradually decreased. Further, addition of 1 equiv. of F- ions to BHP showed the complete disappearance of –OH proton signal as depicted in Figure 8. Moreover, the binding stoichiometric ratio of F- ion with BHP was further supported by 19F NMR experiment. The (H2F)- signal appeared at -124.33 ppm (Figure S11-S12, See ESI) confirms the deprotonation process arose from phenolic –OH proton. Figure 8 1H NMR titration of BHP with F- (0-1equiv) in DMSO-d6 3.6. DFT calculations of BHP with Cd2+/F- ion To recognize the fluorescence enhancement of probe BHP after complexation with F-, DFT calculations were accomplished. The optimized structures of BHP, BHP-Cd2+ and BHP-F- were obtained using DFT/B3LYP-6-311G and B3LYP/LanL2DZ basis sets respectively. The frontier molecular orbital diagram obtained from optimized structure of BHP is presented in Figure 9. Upon binding with Cd2+ ion, the HOMO and LUMO are delocalized over the entire salicyl unit and their energy gap was reduced. It is noteworthy that inhibition of charge transfer in probe BHP renders the reduction of absorbance at 367 nm and 470 nm. Moreover, Complexation of F- ion to the probe BHP leads to lowering of HOMO-LUMO energy gap. In the presence of F-, HOMO and LUMO are distributed over the whole molecule of BHP. From these results, the F- ion was efficiently binded and complexed with BHP than Cd2+ ion. Figure 9. Frontier molecular orbital diagram of BHP, BHP-Cd2+and BHP-F‒ 3.7. Live cell Imaging analysis of BHP in HeLa cells / Zebrafish embryos The cell viability or cytotoxicity analysis of BHP (0–200 µM) against Human HeLa cells were performed using MTT assay. In 100 µM of BHP, cell viability was obtained as too high as 98%. (Figure S13, See ESI). Hence, the probe was sucessfully used for live cell imaging analysis of F- ions in Figure 10. Live cell fluorescence imaging analysis of BHP in HeLa cells. (a) Bright field images of HeLa cells incubated with BHP (25 µM) for 3h (b) Fluorescence merged images of HeLa cells incubated with BHP (25 µM) (c) Fluorescence image of HeLa cells incubated with BHP (25 µM) alone (d) Fluorescence image of HeLa cells incubated with BHP (25 µM) and 25 µM of F‒ ions for 1 h HeLa cells. Further, the HeLa cells were pre-treated with 25 µM of BHP alone for 3 h. Then HeLa cells were seaded with 25 µM of F- ions for 1h. In the absence of F- ions, the probe BHP exposed a weak yellow fluorescence. However, addition of F- ions to the probe BHP induced a bright orange fluorescence (Figure 10). These results endorsed that the probe BHP can be successfully utilized for the intracellular fluorescence imaging analysis of F- ions in HeLa cells. Besides, the exceptional cell viability output of BHP has been further explored in four days Zebrafish embryos. Zebrafish has positioned as a well-known vertebrate model in numerous biological applications. From this perspective, we have utilized also zebrafish embryos as a living animal model to expose the excellent imaging potential of BHP for the detection of F‒ ion in the biological environment (Figure 11) . Figure 11. Fluorescence imaging analysis of F‒ ion in 4 days old Zebrafish embryos developed with BHP and various concentrations of F‒ ion (a) bright field images of BHP (25 µM) alone, (b) fluorescence merged images of BHP and F- ion (25 µM) (c) fluorescence image of BHP (25 µM) alone (d) 25 µM of F‒ ion for 2 h continuously incubated with BHP (25 µM) for 3 h. 3.8. Evaluation of BHP with previous reports The probe BHP has valid and multi features such as single step synthesis, dual-mode recognition, turn-on fluorescence response and colorimetric change. The probe BHP displayed unique sensing property among other dual sensors. Table S1 compares the sensing performance of BHP with recently reported F‒ receptors. Amid, BHP exhibits too low limit of detection when compared with other previously reported chemoreceptors cited in table S1. Also, the limit of detection of BHP is within the range of recommended limits set by both EPA and WHO for F‒ Ions. Moreover, the fluorescence imaging experiments inferred that the probe BHP can be utilized as potential tool for mapping F‒ ion distribution in HeLa cells and Zebrafish embryos. Conclusions We have designed and synthesized a new chromogenic and fluorogenic probe based on salicylhydrazone derivative for the selective and sensitive detection of both Cd2+/F- ions by colorimetrically and fluorimetrically respectively. As per our knowledge, it is a novel simple hydrazone receptor for sensing carcinogenic heavy metal Cd2+ via colorimetric method and biologically significant F‒ ion by both colorimetric and fluorimetric methods. The binding constant value of Cd2+ ion was found to be 4.26×10-4 M by UV-visible method where as 6.03×10-3 and 3.01×10-4 M for F- ion by both UV-visible and fluorescence methods respectively. The limit of detection was found to be 0.05 nM for F- ion. The excellent biological potential of BHP has been successfully utilized for the detection of F- ions in Zebrafish embryos and human HeLa cells. Acknowledgments The authors acknowledge the financial support from the Council of Scientific and Industrial Research, Extramural Research, New Delhi, India (Grant No. 01(2901)17/EMR-II. The Department of Science and Technology, SERB, Extramural Major Research Project (Grant No. EMR/2015/000969), Department of Science and Technology, CERI, New Delhi, India (Grant No. DST/TM/CERI/C130(G) and we acknowledge the DST-FIST, DST-PURSE,DST-IRPHA, UPE programme and UGC-NRCBS, SBS, MKU for providing instrumentation facilities. References Jäkle, F. Chem. Rev. 2010, 110, 3985. 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Bioactive aminooxime ligands based on optically pure (R)-limonene have been synthesized in two steps. Their ruthenium (II) cationic water-soluble complex was prepared by a reaction between dichloro (para-cymene) ruthenium (II) dimers and aminooxime ligands in a 1:2 molar ratio. Antibacterial and antibiofilm activities of the synthetized complex were assessed against Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, and Enterococcus faecalis. The results revealed that the ruthenium (II) complex has higher antibacterial and antibiofilm activities in comparison with free ligands or the enantiopure (R)-limonene. Moreover, microencapsulation of this complex reduced its cytotoxicity and improved their minimum inhibitory concentration and antibiofilm activity toward the considered bacteria. The ruthenium (II) complex targets the bacterial cell membrane, which leads to rapid leakage of intracellular potassium. Our study suggests that the developed ruthenium (II) complexes could be useful as an alternative to conventional disinfectants.

AbstractNew chiral nitrogen ligands based on the substituted mono-and bis(imidazolyl)pyridines have been prepared and characterised. Their complexes with cupric acetate were used as catalysts in the nitroaldolisation reaction. In the case of optically pure complexes of mono(imidazolyl)pyridine, the isolated products were 2-nitro-1-(2-nitrophenyl)ethanols or 2-nitro-1-(4-nitrophenyl)ethanols in overall yields of 49–93 % and with the maximum enantiomeric excess of 15.6 %. The complexes of bis(imidazolyl)pyridine also catalyse the nitroaldol reaction, the yields being 64–90 %, but with zero enantioselective excess.

AbstractUltrasound‐induced circularly polarized luminescence (CPL) was achieved using planar chiral, binuclear clothespin‐shaped trans‐bis(salicylaldiminato)platinum(II) complexes. Solutions of the clothespin‐shaped platinum(II) complexes anti‐1a–c in cyclohexane immediately transformed into stable gels upon brief ultrasound irradiation. The ultrasound gels exhibited intense phosphorescent emissions at room temperature, whereas none of the solution exhibited significant emissions under UV light illumination. Interestingly, gels prepared from optically pure complexes exhibited CPL activity at room temperature with an anisotropy factor of |glum| = 1.5–2.6 × 10−3. The emissive gels were readily converted to the original non‐emissive solution upon heating and cooling to room temperature and could be gelled again by ultrasound irradiation. In addition, chromogenic control from green to red emission can be achieved simply by introducing MeO groups at different positions on the aromatic rings.

Abstract A novel optically pure dinuclear copper(II) complex of a rosin derivative dehydroabietic acid (DHA, HL) was synthesized and fully characterized. The in vitro antitumor activities of the copper(II) complex Cu2(µ2-O)(L)4(DMF)2 (1) were explored and compared with those of a trinuclear iron(III) complex [Fe3(µ3-O)(L)6(CH3OH)2(CH3O)]·H2O (2). 1 was more cytotoxic than 2, and the in vitro cytotoxicity of 1 was comparable to that of cisplatin and oxaliplatin. The metal coordination improved the cytotoxicity of DHA. 1 could arrest cycle in G1 phase and induce apoptosis in MCF-7 cell. 1 increased reactive oxygen species level, GSSG/GSH ratio, and Ca2+ production, and caused the loss of mitochondrial membrane potential (Δψm) in MCF-7 cells. The up-regulated Bax and down-regulated Bcl-2 expression levels, caspase-9/caspase-3 activation, and the release of Cyt c demonstrate that 1 triggered mitochondria-mediated intrinsic apoptosis in MCF-7 cells. Caspase-8/caspase-4 activation and up-regulated Fas expression indicate that death receptor-mediated extrinsic apoptosis was included. Comet assay and up-regulated γ-H2AX and p53 expressions confirmed that 1 caused DNA damage in MCF-7 cells. Moreover, 1 led to enhancement of the biomarker of lipid peroxidation and the indicator of protein carbonylation in MCF-7 cells. All the results suggest that 1 could kill MCF-7 cells by generating oxidative stress, impairing DNA, promoting lipid peroxidation and protein carbonylation, and inducing apoptosis and autophagy. Furthermore, 1 also displayed antimetastatic activities with inhibition of cell invasion and migration, together with antiangiogenesis properties. On the whole, copper complex based on rosin derivatives is worth developing as metal-based antitumor drugs.

Abstract Herein, a series of 36Adamanzane (stable C-N bond) based alkalides possessing alkaline earth metal cation complexed by the 36Adz cage has been designed and studied with theoretical tools. All suggested complexes are within the range of effective NLO materials such as red-shifted λmax (1080 – 1241 nm), narrowed Eg (1.74 to 2.31 eV), lowered Eopt (0.9945– 1.1485 eV), enhanced ∆μ (5.3873-6.2544 au), ameliorated α_O (454.20 – 1400.34 au) and β_O (801301.48 – 819800.06 au) as compared to pure 36Adz (Eg = 10.2 eV, λmax = 179 nm, Eopt = 6.9217, α_O = 241.64 and β_O = 0.02 au). All of the aimed complexes have substantially large α_O as well as β_O values. NBO charges investigations reveal that one of the s-electrons has migrated from the inside metal atom to the outer one, resulting in not only alkalide characteristics but also significant NLO responses for the targeted compounds. This research is useful in the development of new types of excess electron compounds. The findings presented in this study may have implications for future research on high-performance NLO materials, as well as give important references for future research on various alkalides including non-alkali cations.

ABSTRACTWe have functionalized single walled carbon nanotubes (SWNTs) using ruthenium centered organometallic supramolecular dendritic complexes. These dendrimers have multiple binding sites with chemically specified chirality. Most importantly, they are mechanically rigid. We have fabricated field effect transistors (FET) using these functionalized SWNTs. Devices were processed with standard optical lithography and high resolution e-beam lithography. We are using FET response of these devices to study charge injection into the nanotubes and the resultant effect on the tube's transport properties. Organometallic based molecular adsorbents onto the nanotubes effect the transistor response. These functionalized tubes change their majority carriers from holes to electrons in these FETs. We believe this is due to charge transfer from the metal center through the ligand and finally onto the nanotube. This results in the potential for optically altering the carrier density, and therefore the transport properties of the nanotubes.

Four donor‐acceptor boron difluoride complexes based on the carbazole electron donor and the [1,3,5,2]oxadiazaborinino[3,4‐a][1,8]naphthyridine acceptor were designed, synthesized, and systematically spectroscopically investigated in solutions, in dye‐doped polymer films, and in the solid states. The dyes exhibit an intense blue to red solid‐state emission with photoluminescence quantum yields of up to 59% in pure dye samples and 86% in poly(methyl methacrylate) films. All boron complexes show aggregation‐induced emission and reversible mechanofluorochromism. The optical properties of these dyes and their solid state luminescence can be tuned by substitution pattern, i.e., the substituents at the naphthyridine unit. Exchange of CH3‐ for CF3‐groups does not only increase the intramolecular charge transfer character, but also provides a crystallization‐induced emission enhancement.

Novel proton conducting solid polymer electrolyte membranes based on Poly vinyl alcohol (PVA) with Malonic Acid as dopant are prepared by solution cast technique with varying doping concentrations up to 40 wt.%. The electrical conductivity and optical absorption of pure PVA and Malonic aciddoped PVA electrolytes are investigated. DC conductivity behavior is studied in the range 303K to 373K. It is found that PVA: Malonic acid (70:30) electrolyte exhibits the maximum conductivity. The electrical conductivity initially increases with increasing dopant concentration and then showed a decrease beyond 30 wt.% concentration. The increase in conductivity is attributed to formation of charge transfer complexes while the decrease for concentrations above 30 wt.% is due to segregation. Optical absorption studies are made in the wavelength range 200-600 nm and the values of optical band gap (direct and indirect) are estimated. The results obtained are presented and discussed.

AbstractThe Schiff base N,N-bis(salicylidene)-o-phenylenediamine (salophen) was prepared by the condensation of salicylaldehyde with o-phenylenediamine in ethanol solution. Two new Zn(II) and Ni(II) salophen complexes, were synthesized, fully characterized by infrared (IR), 1H NMR spectroscopic measurements, UV–Vis spectra, photoluminescence (PL), and X-ray diffraction (XRD). The prepared complexes were used as phosphors to fabricate complexes/PMMA slab-based luminescent solar concentrators (LSC). The thermal stability of pure and doped PMMA polymer was examined by differential scanning calorimetry. Various parameters such as the optical energy gap, refractive index, AC and DC conductivity, dielectric constant, dielectric loss, Urbach energy, fluorescence quantum yield, and Stokes shift have been calculated and discussed. Optical absorption is carried out in wavelength region 200–900 nm at room temperature before and after the samples have been exposed to sunlight for up to 8 h. Photodegradation studies showed that the Zn(II) complex/PMMA LSC has the lowest rate of degradation compared with Ni(II) complex/PMMA LSC with the same concentration (0.06% weight). I–V characteristics of the photovoltaic devices with and without collectors were examined. The PV cell coupled with LSC shows an increase in maximum efficiency by about 50% compared to the normal one. This indicates that the proposed technique is very useful for improving the efficiency of solar cells.

AbstractWith the advent of the first laser sources and suitable detectors, optical sensor applications immediately also came into focus. During the last decades, a huge variety of optical sensor concepts were developed, yet the forecast for the future application potential appears even larger. In this context, the development of new sensor probes at different scales down to the atomic or molecular level open new avenues for research and development. We investigated an iron based triazole molecular spin-crossover complex changing its absorption characteristics significantly by varying environmental parameters such as humidity, temperature, magnetic or electric field, respectively, with respect to its suitability for a new class of versatile molecular sensor probes. Hereby, besides the investigation of synthesized pure bulk material using different analyzing methods, we also studied amorphous micro particles which were applied in or onto optical waveguide structures. We found that significant changes of the reflection spectra can also be obtained after combining the particles with different types of optical waveguides.The obtained results demonstrate the suitability of the material complex for a broad field of future sensor applications.

AbstractFluoride perovskites have recently attracted great attention due to their unique optical properties. The present study reports for the first time the fabrication of fluoride-based perovskite, CsCaF3, in form of thin films through a combined sol–gel/spin-coating approach using β-diketonate fluorinated precursors. The entire sol–gel process has been carried out in ethanol solution under acid-catalyzed conditions starting from the β-diketonate complexes, Cs(hfa) and Ca(hfa)2•diglyme•H2O (Hhfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione; diglyme = 2–Methoxyethylether), which act as single sources for metal ions and fluorine. A careful optimization of the process parameters, such as molar ratio of the starting mixture, aging time and annealing temperature, has allowed to produce for the first time, selectively and reproducibly, transparent and pure CsCaF3 films. Field-emission scanning electron microscopy and energy dispersive X-ray analyses highlight the formation of films with compact morphologies having a 1:1 stoichiometric ratio of Cs:Ca, uniform throughout the film and compatible with the CsCaF3 phase identified through X-ray diffraction analysis.