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While formamidinium lead iodide (FAPbI3) halide perovskite (HP) exhibits improved thermal stability and a wide band gap, its practical applicability is chained due to its room temperature phase transition from pure black (α-phase) to a non-perovskite yellow (δ-phase) when exposed to humidity. This phase transition is due to the fragile ionic bonding between the cationic and anionic parts of HPs during their formation. Herein, we report the synthesis of water-stable, red-light-emitting α-phase FAPbI3 nanocrystals (NCs) using five different amines to overcome these intrinsic phase instabilities. The structural, morphological, and electronic characterization were obtained using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), and X-ray photoelectron spectroscopy (XPS), respectively. The photoluminescence (PL) emission and single-particle imaging bear the signature of dual emission in several amines, indicating a self-trapped excited state. Our simple strategy to stabilize the α-phase using various amine interfacial interactions could provide a better understanding and pave the way for a novel approach for the stabilization of perovskites for prolonged durations and their multifunctional applications. [ABSTRACT FROM AUTHOR]

The interest in highly luminescent organic-inorganic hybrid perovskite, methylammonium lead bromide (MLB) nanocrystals (NCs) has grown significantly due to their many applications in optoelectronics. However, the biggest hurdle has been the effective use of the materials in large optoelectronic applications and their poor stability in various environmental conditions. To address the problem of the poor stability of highly luminescent MLB nanostructures, we synthesized MLB NCs on the surface of cellulose nanofibers (CNF) for the first time. The synthesized (MLB@CNF) composite shows green emission peak at 529 nm. The scanning electron microscopy images confirm that perovskite NCs are well attached to the surface of cellulose nanofiber. These composite materials offer improved stability and luminescent features in moist environments for over six months. The developed interfacial interaction strategy will provide a novel approach to obtain durable nanocrystals using cellulose-based materials. [ABSTRACT FROM AUTHOR]

Frozen yoghurt rich in β‐carotene and dietary fibre was developed through incorporation of orange peel products. The suitability of two forms of peel viz., candied orange peel (COP) and orange peel powder (OPP), was studied as flavour adjunct in frozen yoghurt. The medium‐fat frozen yoghurt mix was prepared by blending yoghurt base with ice cream mix (25:75, w/w). COP and OPP were used as flavour adjuncts at levels of 8.0 and 2.5% by weight of mixes, respectively. The control (C) frozen yoghurt was devoid of the fruit peel. Incorporation of peel solids yielded frozen yoghurts which had markedly higher protein, carbohydrates, ash and total solids content. OPP used at 2.5% level was preferred over use of COP at 8.0% level as a valued ingredient in the preparation of 'medium‐fat orange frozen yoghurt'. Such product had superior total sensory score when compared to the rest of the samples. The recommended frozen yoghurt was higher in terms of β‐carotene and dietary fibre by 37.20 and 240.0%, respectively, compared to control product. [ABSTRACT FROM AUTHOR]

[Display omitted] Ligand-assisted re-precipitation (LARP) is one of the most practicing techniques for synthesizing colloidal nanocrystals (NCs). But due to its fast reaction kinetics, it offers limited synthesis control. In the present study, we report a novel, precursor silanization-based room temperature technique unveiling slow crystallization of Cs 4 PbBr 6 /CsPbBr 3 dual-phase nanocrystals (DPNCs) protected with a dense silica cloud-like matrix. Unlike conventional LARP, we can observe the tuneable optical bandgap of the DPNCs as a function of reaction time because of the slow reaction kinetics. The as-synthesized DPNCs exhibit a high photoluminescence quantum yield (PLQY) of 76% with ultrahigh stability while retaining ∼ 100% of their initial PLQY in an ambient environment with a relative humidity of 55% for more than 1 year. DPNCs demonstrates ambient photostability of 560 h, and water stability of 25 days. This interesting precursor silanization technique developed here can be extended for the synthesis of other nanomaterials. [ABSTRACT FROM AUTHOR]

[Display omitted] Ligand-assisted re-precipitation (LARP) is one of the most practicing techniques for synthesizing colloidal nanocrystals (NCs). But due to its fast reaction kinetics, it offers limited synthesis control. In the present study, we report a novel, precursor silanization-based room temperature technique unveiling slow crystallization of Cs 4 PbBr 6 /CsPbBr 3 dual-phase nanocrystals (DPNCs) protected with a dense silica cloud-like matrix. Unlike conventional LARP, we can observe the tuneable optical bandgap of the DPNCs as a function of reaction time because of the slow reaction kinetics. The as-synthesized DPNCs exhibit a high photoluminescence quantum yield (PLQY) of 76% with ultrahigh stability while retaining ∼ 100% of their initial PLQY in an ambient environment with a relative humidity of 55% for more than 1 year. DPNCs demonstrates ambient photostability of 560 h, and water stability of 25 days. This interesting precursor silanization technique developed here can be extended for the synthesis of other nanomaterials. [ABSTRACT FROM AUTHOR]

[Display omitted] Halide perovskites (HPs) are used in various applications, including solar cells, light-emitting diodes, lasers, and photodetectors. These materials have recently received a great deal of attention as high-energy radiation detectors and scintillators due to their excellent light yield, mobility-lifetime product (µτ), and X-ray sensitivity. In addition, due to their solution-processability and low cost, perovskite materials could be used to produce thick perovskite films across wide areas, allowing for low-dose X-ray imaging. Perovskite-based scintillators and detectors could eventually replace commercialized products like thallium‐doped cesium iodide (CsI:Tl) and amorphous silicon (Si). Here, we review all of the key properties of HPs, the relevant terminology necessary for radiation detection and scintillation, the physical mechanisms underlying their operation, the fabrication process, and perovskite crystals and thin-films of varying dimensionality used for high-energy radiation detection. We also cover the critical issues and solutions that HPs as detectors, scintillators, and imagers face. [ABSTRACT FROM AUTHOR]

Two sterically crowded benzo‐tetrathiafulvalene (BTTF)‐annulated expanded porphyrins (BTTF7‐F and BTTF8) are synthesized. Detailed photophysical investigations reveal their intrinsic intramolecular charge transfer (CT) character, originated from partial electron transfer from electron‐rich TTF units to the relatively electron‐deficient macrocyclic core. This finding stands in contrast to what was observed in the previously reported Figure‐of‐eight conformer of BTTF‐annulated [28]hexaphyrin (BTTF6), in which a typical π–π* electronic transition from HOMO to LUMO was observed. However, core expansion in BTTF7‐F and BTTF8 makes the oligopyrrole macrocyclic cores relatively more electron‐deficient, facilitating the effective intramolecular CT process. Comparative electrochemical investigations reveal that the current generated at the oxidative region is directly proportional to the number of TTF units attached to the macrocyclic core. This work demonstrates the control of the intramolecular CT process through incremental addition of TTF units to the macrocyclic core. Facile multielectron electrochemical oxidations of these expanded porphyrins suggest that they behave like potential multielectron reservoirs. [ABSTRACT FROM AUTHOR]

The effect of surface passivation on the photoluminescence (PL) emitted by CsPbBr3 micro/nano‐rods coated with Pb(OH)2 is investigated, where a high quantum yield and excellent stability for the emission are found. The CsPbBr3/Pb(OH)2 rods generally present a peak that is blue shifted compared to that seen in rods without a hydroxide cladding at low temperatures. By increasing the temperature, it is further shown that the passivated surface states are very robust against thermal effects and that the PL peak intensity only drops by a factor of 1.5. Localized stimulated emission at defect states found within larger rods is also demonstrated, clarified by spatially resolved confocal PL mapping along the length of the rods. The diffusion parameter of the carrier density distribution is measured to be 5.70 µm for the sky‐blue emission, whereas for the defect lasing site it is found to be smaller than this excitation spot size. [ABSTRACT FROM AUTHOR]

Colloidal organic–inorganic lead halide perovskites have gained tremendous attention due to their excellent optical properties and promising future in optoelectronic applications. However, the lack of large scale synthesis methods and structural instability in moisture conditions restrict their practical applications. We report, for the first time, a gram-scale aqueous synthesis of MAPbBr3 (MA = CH3NH3+) using PbCO3, bottom-up synthesis of MAPbBr3 NCs and in situ bottom-up synthesis of MAPbBr3@poly(3-bromothiophene) nanocomposite. The synthesized nanocomposite material exhibits bright green fluorescence and excellent water-resistivity. Together, the polymer-based bottom-up and in situ encapsulation strategy of MAPbBr3 NCs will pave the way for synthesizing other lead halide water-resistant perovskites that will be used in thin-film based light-emitting devices. [ABSTRACT FROM AUTHOR]

Abstract A novel Schiff base L composed of fluorescein hydrazine and a phenol functionalized moiety has been designed and prepared via cost-effective condensation reaction. The L is utilized for selective sensing of Zn2+ over other environmental and biological relevant metal ions in aqueous alcoholic solution under physiological pH range. The binding of Zn2+ to the receptor L is found to causes ~23 fold fluorescence enhancement of L. The 1:1 binding mode of the metal complex is established by combined UV–Vis, fluorescence, and HRMS (high-resolution mass spectroscopy) spectroscopic methods. The binding constant (K a) for complexation and the limit of detection (LOD) of Zn2+ is calculated to be 2.86 × 104 M−1 and 1.59 μM, respectively. Further photophysical investigations including steady-state, time-resolved fluorescence analysis and spectral investigations including NMR (nuclear magnetic resonance), IR (infrared spectroscopy) suggest introduction of CHEF (chelation enhance fluorescence) with the suppression of C N isomerization and PET (photo-induced electron transfer) mechanism for the strong fluorescent response towards Zn2+. Finally, the sensor L is successfully employed to monitor a real-time detection of Zn2+ by means of TLC (thin layer chromatography) based paper strip. The L is used in the cell imaging study using African green monkey kidney cells (Vero cells) for the determination of exogenous Zn2+ by Immunofluorescence Assay (IFA) process. Graphical Abstract Unlabelled Image Highlights • A novel fluorescein-based probe with a simple structure for recognition of Zn2+ is synthesized via simple Schiff base condensation. • The probe shows promising fluorescence response, excellent selectivity, and high sensitivity (1.59 μM) toward Zn2+. • The binding modes of probe L with Zn2+ ion has been well demonstrated by UV–Vis, fluorescence, HRMS, 13C NMR, and FTIR spectroscopy. • The probe could be used for Zn2+ detection in various solvent medium and also in thin layer chromatography (TLC) paper with quick response. • The probe L serve as an excellent sensor in identifying Zn2+ in intracellular region of African green monkey kidney cells (Vero cells). [ABSTRACT FROM AUTHOR]

The present study deals with the synthesis of polycrystalline n –CdSeS composite films on FTO-coated glass substrate routed through galvanostatic method of deposition at constant temperature from the electrolytic solution containing respective precursors, while varying the concentration of elemental sulfur in the bath. Band gap energies of the nano-structured films were found to lie within the range 2.26–2.48 eV. The structure, composition and morphology of the film matrices were revealed through the respective techniques, XRD, UV–vis spectroscopy and electron microscopy, while, their photo-electrochemical (PEC) properties were determined through several electrochemical investigations. The best ternary CdSeS film was identified with 0.15 M S concentration in the preparative bath. This particular film shows a photoconversion efficiency of 0.94% which is higher than the individual binary systems. The optimized film bears high carrier concentration, almost twice than that of CdSe and thrice than that of CdS films and shows significant photo-response. Furthermore, the inherent stability of the matrix increases with the incorporation of S and the film developed at 0.15 M S is found to be ∼100 times more stable than the bare CdSe films. [ABSTRACT FROM AUTHOR]

Tetrathiafulvalene (TTF) has been extensively explored as a π-electron donor in supramolecular systems. Over the last two decades substantial advances have been made in terms of constructing elaborate architectures based on TTF and in exploiting the resulting systems in the context of supramolecular host–guest recognition. The inherent electron-donating character of TTF derivatives has led to their use in the construction of highly efficient optoelectronic materials, optical sensors, and electron-transfer ensembles. TTFs are also promising candidates for the development of the so-called “functional materials” that might see use in a range of modern technological applications. Novel synthetic strategies, coupled with the versatility inherent within the TTF moiety, are now allowing the architecture of TTF-based systems to be tuned precisely and modified for use in specific purposes. In this critical review, we provide a “state-of-the-art” overview of research involving TTF-based macrocyclic systems with a focus on their use in supramolecular host–guest recognition, as components in non-covalent electron transfer systems, and in the construction of “molecular machines”. [ABSTRACT FROM AUTHOR]

[Display omitted] • Environmentally friendly zero-dimensional Mn(II) complex synthesized using solvent-free mechanochemical grinding. • Bright green phosphorescence with a narrow emission spectrum and high quantum yield is observed. • A record high EQE of 11.42% and CE of 56.84 cd/A is achieved for a green-PHOLED. • The first ever warm-white OLED is fabricated with a CRI of 78 using MnBz as the green component. Low-dimensional, earth-abundant, non-toxic, and crystalline materials are highly promising candidates for organic light-emitting diodes (OLEDs). Here, we report a zero-dimensional (0D) Mn(II) complex, [Ph 3 BzP] 2 [MnBr 4 ] (MnBz) synthesized using a solvent-free mechanochemical grinding method. MnBz exhibits a bright and narrow green emission peak at 517 nm originating from the discrete [MnBr 4 ]2− unit separated by large hydrophobic quaternary phosphonium ions in solid state, with excellent stability and a remarkably high PLQY of 53%. Theoretical calculations indicate that the conduction band derives from the C-2p (benzene ring) and Mn-3d states, while the valence band originates from the Br-4p and Mn-3d states. Green phosphorescent OLEDs (PHOLEDs) based on the 0D MnBz exhibit an excellent external quantum efficiency and current efficiency of 11.42% and 56.84 cd A−1, respectively, thus outperforming the currently available Mn(II) complex-based OLEDs. Furthermore, for the first time, an RGB warm-white OLED is fabricated using the Mn(II) complex as the green component, exhibiting an excellent CRI of 78 with a CCT of 3740 K. This successful development of a high-performance, stable green-PHOLED using MnBz while also demonstrating its potential as an emitter candidate for white OLEDs, may inspire the future development of cheaper alternatives for a variety of emission applications and commercial display devices. [ABSTRACT FROM AUTHOR]

Polycrystalline n-type CdSe thin films were deposited from aqueous bath at room temperature by periodic voltammetry for use in photo-electrochemical (PEC) solar cells. The influence of periodic scans on the functional properties of the chalcogenide films was thoroughly investigated through electron microscopy (SEM), X-ray diffraction (XRD), UV-visible spectrometry, and electrochemical techniques. The film thickness increases with the number of periodic scans, and the spectral measurements identify the optical band gap in the range 1.55-1.72 eV. The CdSe films show typical X-ray diffraction patterns of hexagonal crystal structure with particle size 20-30 nm, uniformly distributed throughout the matrix. PEC characteristics including photo-current density, conversion efficiency ( η), fill factor ( FF), and durability of the films were evaluated by the help of respective electrochemical techniques. The voltammetric cycle number was optimized which enable to identify the best CdSe film exhibiting photo-conversion efficiency of ~1% with minimum photocurrent decay. [ABSTRACT FROM AUTHOR]

Nano-porous titania matrices were doped with AgNPs by UV assisted reduction of AgNO 3 solution to fabricate the photo-anode in dye sensitized solar cell using N3 as the absorber dye. The composite matrices were subjected to physicochemical characterization using XRD, TEM, XPS, EDAX, FESEM, spectral and micro Raman techniques. Electrochemical characterizations of the Ag-TiO 2 matrices were carried out to evaluate the photoresponse, current-voltage output, interfacial charge transfer and stability of the DSSC under illumination of 10–100 mW/cm 2 using white LED light source. The dye-electrode embedded with an optimal level of Ag, produced solar conversion efficiency of 11.17% and IPCE 73%. Attempt was taken to make the plasmon based DSSC more low light sensitive by using triphenylmethylphosphonim iodide (TPMPI) as the electrolyte component. [ABSTRACT FROM AUTHOR]

A series of d/f dinuclear complexes Ir•Ln [where Ln = Eu(III), Gd(III), Yb(III) and Nd(III)] are reported. The core structure consists of a rigid skeleton containing two different types of receptor site in a single molecular motif designed to combine a transition metal ion [Ir(III)] and a lanthanide ion [Ln(III)] in different binding sites at either end of fully conjugated bridge to facilitate d → f energy-transfer following photoexcitation of the Ir(III)-based antenna unit. Steady state and time-resolved photophysical experiments on these compounds revealed that the energy-transfer is feasible only in case of Ir•Yb and Ir•Nd systems, affording sensitized emission from the Yb(III) or Nd(III) centres. Such EnT is not possible in the Ir•Eu dyad as the excited state energy of the Ir(III) unit is insufficient to sensitise the excited state of the Eu(III) centre. [ABSTRACT FROM AUTHOR]

For the first time, we have synthesized APbBr3 (A = Cs+/MA+/FA+, where MA+ = CH3NH3+ and FA+ = CH(NH2)2+) bulk as well as nanoparticles (NPs) by solid-state reactions at room temperature. This facile strategy yields different shape structures e.g. square and rectangular (CsPbBr3), spherical (MAPbBr3) and parallelogram (FAPbBr3) NPs. [ABSTRACT FROM AUTHOR]

After the epochal discovery of the "organic metal", namely, tetrathiafulvalene (TTF)-7,7,8,8-tetracyano-p-quinodimethane (TCNQ) dyad in 1973, scientists have made efforts to derivatize TTF for constructing various supramolecular architectures to control the charge-transfer processes by adjusting the donor-acceptor strength of the dyads for numerous applications. The interesting inherent electronic donor properties of TTFs control the overall electrochemical properties of the supramolecular structures, leading to the construction of highly efficient optoelectronic materials, photovoltaic solar cells, organic field-effect transistors, and optical sensors. Modified TTF structures thus constitute promising candidates for the development of so-called "functional materials" that could see use in modern technological applications. The versatility of the TTF unit and the pioneering synthetic strategies that have been developed over the past few decades provide opportunities to tune the architecture and function for specific purposes. This review covers the "state of the art" associated with TTF-annulated oligopyrrolic macrocyclic compounds. Points of emphasis include synthesis, properties, and potential applications. [ABSTRACT FROM AUTHOR]

In this investigation multilayered conjugate films are formulated with Bi 2 S 3 and CdS nano particles (NPs) on FTO glass substrate. Thin layer Bi 2 S 3 was deposited and subsequently covered with various levels of CdS coating. Optical properties and XRD analysis of the films show existence of both the compound phases. The morphology of the films studied through electron microscopy reveals coverage of spherical CdS NPs on the network of Bi 2 S 3 NPs. The electrochemical impedance records and performances output characteristics of the n -type films show that the most efficient co-sensitizer matrix is produced with deep coating of CdS on thin layer of Bi 2 S 3 . [ABSTRACT FROM AUTHOR]

The long carrier lifetimes and low nonradiative recombination rates of organic-inorganic hybrid perovskites have opened new avenues in fabrication of highly efficient solar cells, light-emitting diodes, and lasers. Controlling shapes and organization of newly synthesized perovskite nanostructures should greatly expand their practical application. Here, we report a colloidal synthetic approach to the preparation of methylammonium lead bromide (CH3NH3PbBr3) quantum wires by controlling their surface ligand chemistry to achieve well-defined superstructures. Quantum wire formation was proceeded by the appearance of pearl-necklace assemblies of spherical CH3NH3PbBr3 nanocrystals as intermediates formed mainly through dipolar interactions. The diameter of the quantum wires (-3.8 nm) was found to be larger than the precursor spherical CH3NH3PbBr3 nanocrystals (-2.4 nm). Our experimental findings support mesoscale growth and assembly into CH3NH3PbBr3 quantum wires driven by cooperative interactions between nanocrystals caused by van der Waals interactions and chain interdigitation of surface passivating ligands. The quantum wires displayed an aspect ratio as high as 250 with photoluminescence quantum yield of -60% and lifetime of -90 ns, and were aligned in bundles. Our simple colloidal synthetic approach and detailed characterization will inspire rational design of methodologies to prepare diverse anisotropic semiconductor perovskite nanostructures and superstructures, which together will increase the versatility and performance of perovskite materials in optoelectronic and photovoltaic device applications. [ABSTRACT FROM AUTHOR]

Proper fusion of fluorescence mechanisms in a single fluorophore unit is highly desirable to obtain better sensitivity, as well as selectivity towards a particular metal ion. In this regard, a Zn2+ chemosensor exhibiting strong fluorescence through synergistic CHEF-PET-ESIPT fluorescence mechanism has not received substantial deployment. This type of chemosensor provides an ample avenue to detect metal ions with a large stokes shift and are useful in living cell imaging study. Herein, we report an unparalleled Zn2+ chemosensor (L) based on these three types of fluorescence mechanisms by condensing 2,6-diformyl-4-methylphenol and 2-hydrazinyl-4,6-dimethylpyrimidine. All the three types of mechanism were experimentally verified by UV-Vis, fluorescence and time resolved photoluminescence (TRPL) spectroscopic evaluation. The sensor L and Zn2+ formed a 1 : 1 ratio complex demonstrating a high binding constant value (Ka = 4.812 × 105 M−1) and L showed clear discrimination from the Cd2+ ion. The limit of detection (LOD) and limit of quantification (LOQ) were calculated to be 9.727 × 10−7 (M) and 3.24 × 10−6 (M), respectively. We have also shown that cell imaging can be performed using L without many cytotoxicity concerns. [ABSTRACT FROM AUTHOR]

Polycrystalline semiconductor films of BiCdTe composites were electro-deposited on ITO coated glass through a voltammetric technique under variable periodic cycles. The crystal structure and composition of the films were determined by X-ray diffraction, scanning electron microscopy, atomic force microscopy and energy dispersive X-ray analysis and the optical features were recorded using a UV-visible spectrometer. The band gap energy of the ternary films was found to be within the range of 1.5–1.7 eV. Electrochemical impedance spectroscopy provided important information regarding the interfacial properties of the films in polysulphide medium. The current–voltage measurements for the photo-electrochemical solar cells fabricated with the prepared films as anode components exhibited encouraging photo-response and improved functional properties. The BiCdTe composite films were further subjected to anodic corrosion studies followed by anodic stripping voltammetry and the stability of the films was compared with that of CdTe. An optimal composition of the film matrix shows a performance efficiency of 4.3%, significantly high photo current and considerably greater stability compared to the individual binary chalcogenide films. [ABSTRACT FROM AUTHOR]

A new class of substituted porphyrins has been developed in which a different number of cyclometalated PtII C^N^N acetylides and polyethylene glycol (PEG) chains are attached to the meso positions of the porphyrin core, which are meant for photophysical, electrochemical, and in vitro light-induced singlet oxygen (1O2) generation studies. All of these ZnII porphyrin-PtII C^N^N acetylide conjugates show moderate to high ( Φ Δ=0.55 to 0.63) singlet oxygen generation efficiency. The complexes are soluble in organic solvents but, despite the PEG substituents, slowly aggregate in aqueous solvent systems. These conjugates also exhibit interesting photophysical properties, including near-complete photoinduced energy transfer (PEnT) through the rigid acetylenic bond(s) from the PtII C^N^N antenna units to the ZnII porphyrin core, which shows sensitized luminescence, as shown by quenching of PtII C^N^N-based luminescence. Electrochemical measurements show a set of redox processes that are approximately the sum of what is observed for the PtII C^N^N acetylide and ZnII porphyrin units. UV/Vis spectroscopic properties are supported by DFT calculations. [ABSTRACT FROM AUTHOR]

In the past few years, there has been immense interest in the preparation of sustainable photocatalysts composed of semiconductor nanocrystals (NCs) as one of their components. We report here, for the first time, the effects of structural parameters of copper indium diselenide (CuInSe2) NCs on visible light-driven photocatalytic degradation of pollutants under homogeneous conditions. Ligand exchange reactions were performed replacing insulating, oleylamine capping with poly(ethylene glycol) thiols to prepare PEG-thiolate-capped, 1.8-5.3 nm diameter CuInSe2 NCs to enhance their solubility in water. This unique solubility property caused inner-sphere electron transfer reactions (O2 to O2•-) to occur at the NC surface, allowing for sustainable photocatalytic reactions. Electrochemical characterization of our dissolved CuInSe2 NCs showed that the thermodynamic driving force (-ΔG) for oxygen reduction, which increased with decreased NC size, was the dominant contributor to the overall process when compared to the contribution light absorption and the Coulombic interaction energies of electron-hole pair (Je/h). A 2-fold increase in phenol degradation efficiency (from 30 to ~60%) was achieved by controlled variation of the diameter of CuInSe2 NCs from 5.3 to 1.8 nm. The surface ligand dependency of photocatalytic efficiency was also investigated, and a profound effect on phenol degradation was observed. Our PEG-thiolate-capped CuInSe2 NCs showed photocatalytic activity toward other organic compounds, such as N,N-dimethyl-4-phenylenediamine, methylene blue, and thiourea, which showed decomposition under visible light. [ABSTRACT FROM AUTHOR]

In the past few years, there has been immense interest in the preparation of sustainable photocatalysts composed of semiconductor nanocrystals (NCs) as one of their components. We report here, for the first time, the effects of structural parameters of copper indium diselenide (CuInSe2) NCs on visible light-driven photocatalytic degradation of pollutants under homogeneous conditions. Ligand exchange reactions were performed replacing insulating, oleylamine capping with poly(ethylene glycol) thiols to prepare PEG-thiolate-capped, 1.8-5.3 nm diameter CuInSe2 NCs to enhance their solubility in water. This unique solubility property caused inner-sphere electron transfer reactions (O2 to O2•-) to occur at the NC surface, allowing for sustainable photocatalytic reactions. Electrochemical characterization of our dissolved CuInSe2 NCs showed that the thermodynamic driving force (-ΔG) for oxygen reduction, which increased with decreased NC size, was the dominant contributor to the overall process when compared to the contribution light absorption and the Coulombic interaction energies of electron-hole pair (Je/h). A 2-fold increase in phenol degradation efficiency (from 30 to ~60%) was achieved by controlled variation of the diameter of CuInSe2 NCs from 5.3 to 1.8 nm. The surface ligand dependency of photocatalytic efficiency was also investigated, and a profound effect on phenol degradation was observed. Our PEG-thiolate-capped CuInSe2 NCs showed photocatalytic activity toward other organic compounds, such as N,N-dimethyl-4-phenylenediamine, methylene blue, and thiourea, which showed decomposition under visible light. [ABSTRACT FROM AUTHOR]

In the past few years, there has been immense interest in the preparation of sustainable photocatalysts composed of semiconductor nanocrystals (NCs) as one of their components. We report here, for the first time, the effects of structural parameters of copper indium diselenide (CuInSe2) NCs on visible light-driven photocatalytic degradation of pollutants under homogeneous conditions. Ligand exchange reactions were performed replacing insulating, oleylamine capping with poly(ethylene glycol) thiols to prepare PEG-thiolate-capped, 1.8-5.3 nm diameter CuInSe2 NCs to enhance their solubility in water. This unique solubility property caused inner-sphere electron transfer reactions (O2 to O2•-) to occur at the NC surface, allowing for sustainable photocatalytic reactions. Electrochemical characterization of our dissolved CuInSe2 NCs showed that the thermodynamic driving force (-ΔG) for oxygen reduction, which increased with decreased NC size, was the dominant contributor to the overall process when compared to the contribution light absorption and the Coulombic interaction energies of electron-hole pair (Je/h). A 2-fold increase in phenol degradation efficiency (from 30 to ~60%) was achieved by controlled variation of the diameter of CuInSe2 NCs from 5.3 to 1.8 nm. The surface ligand dependency of photocatalytic efficiency was also investigated, and a profound effect on phenol degradation was observed. Our PEG-thiolate-capped CuInSe2 NCs showed photocatalytic activity toward other organic compounds, such as N,N-dimethyl-4-phenylenediamine, methylene blue, and thiourea, which showed decomposition under visible light. [ABSTRACT FROM AUTHOR]

Two novel complexes [Mn 2 (phmp) 2 ](ClO 4 ) 2 ( 1 ) and [Ni 2 (phmp)(μ-H 2 O)(H 2 O) 4 ](NO 3 ) 3 ( 2 ) were synthesized using an “end-off” compartmental ligand [H-phmp = 4-Methyl-2,6-bis-(pyridin-2-yl-hydrazonomethyl)-phenol] with Mn(II)-perchlorate and Ni(II)-nitrate salts as metal precursors. Both these complexes were characterized by spectroscopic (IR, UV–Vis) and X-ray crystal structure analysis. The ligand, H-phmp acts as a pentadentate NNONN donor for both the metal complexes and the geometry of the complexes 1 and 2 is distorted octahedral. The DFT optimized bond distances and angles are well correlate to the X-ray structure bond parameters. For complex 1 the transitions at 435 nm and 428 nm have mixed MLCT ( dπ (Mn) → π * (L)) and ILCT ( π (L) → π * (L)) character whereas other transitions correspond to intra-ligand charge transfer transitions (ILCT). For complex 2 , weak transitions at 464 and 405 nm correspond to ligand to metal charge transfer transitions (LMCT) ( π (L) → dπ (Ni)) and most of the other transitions have ILCT character. As anticipated, various weak forces, i.e. anion–π/π–anion/anion–π/π–NH interactions as well as C–H/π interaction, play a key role in stabilizing the self-assembly process observed for both compounds. [ABSTRACT FROM AUTHOR]

A new rigid and conjugated ligand structure connecting phenanthroline and poly(amino-carboxylate) binding sites provides d–f complexes which show high potential for use in dual (luminescence + magnetic resonance) imaging and for optimisation of d → f photoinduced energy-transfer. [ABSTRACT FROM AUTHOR]

Organic-inorganic hybrid perovskite materials continue to attract significant interest due to their optoelectronic application. However, the degradation phenomenon associated with hybrid structures remains a challenging aspect of commercialization. To overcome the stability issue, we have assembled the methylammonium lead bromide nano islands (MNIs) on the backbone of poly-3-dodecyl-thiophene (PDT) for the first time. The structural and morphological properties of the MNI-PDT composite were confirmed with the aid of X-ray diffraction (XRD) studies, Field emission scanning electron microscope (FESEM), and X-ray photoelectron spectroscopy (XPS). The optical properties, namely absorption studies, were carried out by ultraviolet-visible spectroscopy. The fluorescent behavior is determined by photoluminescence (PL) spectroscopy. The emission peak for the MNI-PDT was observed at 536 nm. The morphology studies supported by FESEM indicated that the nano islands are completely covered on the surface of the polymer backbone, making the hybrid (MNI-PDT) stable under environmental conditions for three months. The interfacial interaction strategy developed in the present work will provide a new approach for the stabilization of hybrids for a longer time duration. [ABSTRACT FROM AUTHOR]

All-inorganic and organic–inorganic hybrid perovskite solar cells (PSCs) have taken a quantum leap owing to their high performance and low-cost solution processability. Their efficiency has been dramatically increased up to ∼26%, matching the conventional inorganic photovoltaics like monocrystalline Si (26.1%), polycrystalline Si (21.6%), CdTe (22.1%), and CIGS (22.3%). Such outstanding performance has been achieved due to their excellent optoelectronic properties, such as a direct bandgap in the visible region, a very high absorption coefficient, a long charge-carrier diffusion length, and ambipolar carrier transport characteristics. FAPbI3 (FA = formamidinium) and CsPbI3 perovskites among the pool of perovskites are recommended for solar cell applications because they meet all the requirements for photovoltaic applications. However, the fundamental problem of these perovskites is that their photoactive black phase is highly unstable under ambient conditions due to small and large sizes of Cs+ and FA+ ions, respectively. The instability of the black phase of these perovskites hinders their applications in photovoltaic devices as a high-quality light absorber layer. Several approaches have been employed to prevent the formation of the photo-inactive yellow phase or to enhance the stability of the black phase of perovskites, such as dimensional and compositional engineering, the addition of external additives, and dimensional engineering. This perspective summarizes the various methods for stabilizing the black phase of CsPbI3 and FAPbI3 perovskites at room temperature as well as their application in photovoltaic devices. [ABSTRACT FROM AUTHOR]

A novel electron rich, tetrathiafulvalene fused zinc porphyrin, (TTF)4PZn, has been newly synthesized and characterized using spectral and electrochemical methods. In spite of the presence of eight t-butyl groups, (TTF)4PZn exhibited appreciable aggregation in solution. Scanning electron microscopic (SEM) imaging of the aggregates revealed their spherical particulate morphology. Attenuation of intermolecular aggregation was possible by metal-ligand coordination of a nitrogenous ligand. Further, using this strategy, a donor-acceptor hybrid was formed by coordinating imidazole functionalized fullerene as an electron acceptor. The occurrence of intrasupramolecular ultrafast photoinduced charge separation has been established using fluorescence and transient absorption spectroscopic techniques. The determined rate of charge separation, kCS, and rate of charge recombination, kCR were found to be 1.4 × 1011 s-1 and 2.5 × 106s-1, respectively. The lower kCR values indicate charge stabilization in the assembled donor-acceptor conjugate via an electron transfer-hole transfer mechanism. [ABSTRACT FROM AUTHOR]

The well known rhodamine framework offers an ideal model for the development of fluorescence enhanced chemosensors. Herein, a novel and simple molecule chemosensor, (E)-2-((benzo[d][1,3]dioxol-4-ylmethylene)amino)-3′,6′-bis(diethylamino)spiro[isoindoline-1,9′-xanthen]-3-one ( L ), has been designed by combining a rhodamine B hydrazide and a benzo[d][1,3]dioxole-4-carbaldehyde in a single molecule to prove the selectivity and sensitivity for Al 3+ and Cr 3+ in a dual-channel mode (fluorescence emission and UV–Vis). The signal transduction occurred by the increase of conjugation in the ring-open form than in the ring-closed form. Furthermore, the chemosensor L could also be used as an imaging probe without cytotoxicity for uptake and detection of Al 3+ ion in HeLa cells. [ABSTRACT FROM AUTHOR]

5-methoxy isatin-appended rhodamine dye, (E)-3'-(diethylamino)-6'-(ethyl(methyl)amino)-2-((5-methoxy-2-oxoindolin-3-ylidene)amino)spiro[isoindoline-1,9'-xanthen]-3-one (L) has been designed, synthesized, and characterized by different spectroscopic techniques. The chemosensor L shows high sensitivity towards Al3+ ions without interference from other biologically important cations in DMSO/H2O (1/9, v/v) media. The Al3+-ion promoted ring opening of the rhodamine spirolactam ring in chemosensor L evokes a fluorescence turn-on response via chelation-enhanced fluorescence (CHEF) process. Its lowest detection limit for Al3+ is 2.2x10-8 M, and displays a significant color change from almost colorless to deep pink in the presence of Al3+. The titration results show a 1:1 complex formation between chemosensor L and Al3+. [ABSTRACT FROM AUTHOR]

A novel fluorescent chemosensor based on a rhodamine derivative (L) was designed, synthesized, and used as a selective Al+3 ion sensor. Upon addition of Al3+ to an aqueous-acetonitrile solution of L, the development of a strong fluorescence signal by a chelation-enhanced fluorescence (CHEF) process was observed with an attractive glowing orange emission. This sensor shows high selectivity towards Al3+ ions in the presence of other competing metal ions. The fluorescence quantum yield of L–Al3+ (Φf = 0.30) was found to be very high compared to the bare ligand. The limit of detection (LOD) of Al3+ ions was calculated to be 2 × 10−8 M by fluorescence titration. The 1 : 1 binding stoichiometry of the metal complex was established by combined UV-vis, fluorescence and TOF-MS spectroscopy. [ABSTRACT FROM AUTHOR]

We have highlighted different driving forces, various synthetic parameters and processes for the self-assembly of various perovskite nanocrystals with different morphologies and optoelectronic properties. We have also discussed new design strategies for monocomponent and multicomponent perovskite nanocrystals, chiral perovskites, heterostructures, and stability issues of these superlattices. [Display omitted] The self-assembly phenomenon plays a significant role in atomic, molecular, and biological self-assemblies. This phenomenon has also been found in colloidal nanocrystals (NCs). Self-assembly of colloidal NCs into superstructures is a flexible and promising approach for manipulating nanometre-sized particles and exploiting physical and chemical properties that are distinct from both individual nanoparticles and bulk assemblies. The development of superlattices (SLs) of colloidal perovskite NCs through self-assembly has recently attracted remarkable attention; it is quickly developing as a new frontier in nanotechnology. This review presents the different driving forces, crucial factors for self-assembly of perovskite NCs, recent developments in the synthesis, and properties of self-assembled colloidal perovskite NCs. We also discuss the formation of various SLs from perovskite NCs with different morphologies. Finally, we shed light on multiple challenges in developing numerous perovskite SLs for optoelectronic devices. [ABSTRACT FROM AUTHOR]

A new chelating ligand [4-methyl-2,6-bis-(pyridin-2-yl-hydrazonomethyl)-phenol] (1) was prepared by the condensation of 2-hydrazinylpyridine with 2,6-diformyl-p-cresol. Compound 1 exhibits weak fluorescence due to intramolecular photoinduced electron transfer (PET). The sensor (1) demonstrates Zn2+-specific emission enhancement due to the “PET off” process through a 1 : 1 binding mode with the metal ion. The fluorescence quantum yield of chemosensor 1 is only 0.020, and it increases more than 14-fold (0.280) in the presence of one equivalent of the zinc ion. Interestingly, the introduction of other metal ions causes the fluorescence intensity to remain either unchanged or weakened except for Cd2+. The new sensor showed ‘naked-eye’ detection of Zn2+ ions: a color change of the solution from colorless to yellow. Ratiometric displacement of Cd2+ ions from the complex by Zn2+ ions supports the formation of a more stable sensor–Zn2+ complex over the sensor–Cd2+ complex. The experimental findings have been correlated with theoretical results using the B3LYP functional and 6-31G (d, p), LANL2DZ basis set for Cd2+ (2) and Zn2+ (3) complexes, respectively, by the Density Functional Theory (DFT) method. Moreover, the ability of probe 1 to sense Zn2+ within human melanoma cancer cells has been explored, and the Zn2+-probing process in living cells was found to be reversible with zinc chelator solution of N,N,N,N-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) or EDTA. [ABSTRACT FROM AUTHOR]

Ageing in humans is usually accompanied by deterioration in physical fitness and increased susceptibility to disease, adding to the economic burden of the person concerned. Inadequate food intake, reduced desire to eat, decline in food digestion or absorption, compromise in nutritional metabolic pathways, poor dental hygiene or preponderance of chronic diseases, which are commonly found in the elderly, can lead to an increased risk of under-nutrition. Adequate dietary nutrition has an undisputed role in healthy ageing. Among the various nutrients, proteins play an important role in geriatric health. This review emphasizes the nutritional aspects of milk-based whey proteins and their role in tackling health problems in the geriatric population. Nutritionally rich whey protein constituents such as β-lactoglobulin, α-lactalbumin, bovine serum albumin, lactoferrin and proteose peptone have all been reported to have a plethora of functional roles in various biological processes and organ systems in geriatrics and thus help in the management of geriatric health problems through proper nutrition. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The homoleptic [2×2] tetranuclear compound [Cu4(PyPzCAP)4](NO3)4·8H2O (1) and the pentanuclear Mn(II) cluster [Mn5(PyPzCAP)6](ClO4)4·4C6H6 (2) are self-assembled from the ditopic pro-ligand HPyPzCAP [(5-methyl-1-(pyridin-2-yl)-N′-[1-(pyridin-2-yl)ethylidene]-1H-pyrazole-3-carbohydrazide)]. Complex 1 is almost a square grid, and all the Cu(II) centers show a distorted octahedral environment with an N4O2 chromophore. Complex 2 has a pentanuclear core with a trigonal bipyramidal arrangement of the Mn(II) atoms. The axial Mn centers bear an N3O3 chromophore and the equatorial centers have an N4O2 distorted octahedral arrangement. Complex 1 shows a ferromagnetic exchange interaction (J =+4.62cm−1 and g =2.05), whereas 2 shows weak an antiferromagnetic interaction (J =−2.73cm−1 and g =2.02). Both complexes 1 and 2 catalyze the allylic oxidation of cyclohexene to cyclohex-2-ene-1-one with good selectivity and an excellent overall turnover number. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new pyrimidine derived Schiff Base ligand (L) was synthesized. [•] One zinc (1) and one cadmium (2) complexes have been synthesized and characterized. [•] The geometries of both complexes were optimised in the singlet state by DFT method. [•] TDDFT calculations have been performed. [•] Complex 1 exhibits intraligand 1(π→π∗) fluorescence. [ABSTRACT FROM AUTHOR]

Abstract: A novel rhodamine-based chemosensor, 3′,6′-bis(diethylamino)-2-((2,7-dimethoxy-9H-fluoren-9-ylidene)amino)spiro[isoindoline-1,9′-xanthen]-3-one (1) for aluminum ion, was designed and synthesized. Compound 1 is an orange colored, weak fluorescent compound which was synthesized via one-step facile reaction of rhodamine B hydrazide with 2,7-dimethoxy-9H-fluoren-9-one in MeOH. When Al3+ salt was added in methanol:water (30:70, v/v) solution then spirolactum ring of 1 was opened. The absorbance and fluorescence of the mixed solution were increased dramatically because of the opening of the lactum ring. Thus, signal transduction occurred via reversible CHEF (chelation-enhanced fluorescence) mechanism in the range 580–584nm. [Copyright &y& Elsevier]

Abstract: A pyrazole based ditopic ligand 5(E)-5-methyl-N′-(pyridin-2-ylmethylene)-1H-pyrazole-3-carbohydrazide (PzOPyH), prepared by the reaction between 5-methylpyrazole-3-carbohydrazide and pyridine-2-carbaldehyde, reacts with Mn(ClO4)2·6H2O to form a self-assembled, antiferromagnetically coupled alkoxide bridged pentanuclear Mn(II) homoleptic cluster complex [Mn5(PzOPy)6](ClO4)4 (1). The complex has a central Mn5(μ-O6) core involving six ligand molecules. This pentanuclear core has a trigonal bipyramidal arrangement of Mn(II) atoms, where, the axial metal centers (Mn2 and Mn_2) have a N3O3 chromophore and the equatorial centers (Mn1, Mn_1 and Mn3) have N4O2 chromophore with distorted octahedral arrangement around the metal centers. Intramolecular antiferromagnetic interaction between Mn(II) centers (J =−1.42, S =5/2) is the signature of the molecule. [Copyright &y& Elsevier]

Abstract: Pyrazole based ditopic ligand HL1 ((Z)-N′-(5-methyl-1H-pyrazole-3-carbonyl) picolinohydrazonamide) reacts with Cd(ClO4)2·6H2O and Zn(ClO4)2·6H2O to form a self assembled pentanuclear Cd(II) complex [Cd5(L1)6](ClO4)4 (1) and a mononuclear Zn(II) complex [Zn(HL1)2](ClO4)2 (2). On the other hand, HL2 ((Z)-N′-(5-methyl-1H-pyrazole-3-carbonyl) pyrazine-2-carbohydrazonamide) also forms a mononuclear [Zn(HL2)](ClO4)2(MeOH)2 (3) with Zn(ClO4)2.6H2O. All these complexes have been characterized crystallographically and spectroscopically. The Cd(II) complex (1) has a pentanuclear core with trigonal bipyramidal arrangement of Cd(II) atoms, where, the axial metal centers (Cd2 and Cd5) have N3O3 chromophore and the equatorial centers (Cd1, Cd3 and Cd4) have N4O2 chromophore with distorted octahedral arrangement around the metal centres. In 2 and 3, the NNO donor ligand molecules in their ketoimine form produce distorted octahedral environment around the Zn(II) centre with N4O2 chromophore utilizing pyridine/pyrazine N, one azomethine N and one carbohydrazide O atoms. Here, the pyrazole ring N atoms remain silent in coordination process. On the other hand, in 1, the same ligand HL1 coordinates in its deprotonated imineol form and functions as N3O donor, while, the pyrazole N atoms take part in coordination process. Ligands HL1 and HL2 are fluorescence silent but complexes 1, 2 and 3 show considerable fluorescence. The fluorescence intensity of 1 is higher than that of 2 and 3. [Copyright &y& Elsevier]

Abstract: Three new zig-zag 1D coordination polymers and a binuclear complex of Cu(II) involving pyrazole based tri- and pentadentate schiff base ligands (Z)-2-(2-(5-methyl-1H-pyrazole-3-carbonyl)hydrazono)-2-phenylacetic acid (L′1) and (Z)-2-(2-(5-methyl-1-(pyridin-2-yl)-1H-pyrazole-3-carbonyl)hydrazono)-2-phenylacetic acid (L′2) are reported in this work. The ligand precursors L1 and L2 have been transformed into L1′ and L2′ during the course of reaction with metal ions in which the ester groups have been changed to carboxylate group. The 1D coordination polymers, namely, [Cu(L′1)(ClO4)2(H2O)] n (1), [Cu(L′2)(ClO4)] n (3), [Cu(L′2)(NO3)] n (4) and a binuclear complex [Cu2(L′1)2Cl2] (2) have been synthesized. The complexes 1–3 are of distorted octahedral geometry and the complex 2 is distorted square pyramidal. Interestingly, these structural variations are dependent on counterions and substituent on the pyrazole ring. These have been characterized by elemental analyses, UV, IR, single crystal X-ray diffraction, electrochemical and photoluminescence studies. L′1 serves as tridentate NNO donor where pyrazole nitrogen, azomethine nitrogen and ligand carboxylate group are coordinatively active, leaving the carbonyl oxygen of carbohydrazide part inactive. The same situation (coordination modes) arises in another pentadentate NNNOO donor L′2 where extra pyridine nitrogen is coordinated. The complexes 3 and 4 have considerable fluorescence emission while the rest of the complexes and the ligand molecules are fluorescent silent. [Copyright &y& Elsevier]

Abstract: Thin films of Bi2Se3 have been deposited onto fluorine-doped tin oxide (FTO) – coated glass substrates from non-aqueous bath with the help of galvanostatic electrodeposition technique. The deposited films were subjected to heat treatment at different temperatures in aerated condition and characterized there after. The X-ray diffraction analysis showed the polycrystalline nature of the films and optical absorption technique employed on the as deposited films revealed the presence of direct transition with band gap energy 1.56eV which after annealing increased up to the value of 1.65eV. Stoichiometric composition of the film was determined through energy dispersive X-ray analysis. The stoichiometry was maintained within a short temperature range. The scanning electron micrographs of the films demonstrate a ‘fishing net’ type of highly porous structure with ‘foamy’ appearance. In order to ascertain the stability of the films towards anodic oxidation electrochemical polarization studies were conducted in aqueous medium followed by anodic stripping voltammetry to estimate the dissolved cations during polarization. Films annealed within an optimal temperature range were found to bear distinguished photoelectrochemical properties as regard to solar cell applications. [Copyright &y& Elsevier]

A series of tetrathiafulvalene (TTF)-annulated porphyrins, and their corresponding ZnII complexes, have been synthesized. Detailed electrochemical, photophysical, and theoretical studies reveal the effects of intramolecular charge-transfer transitions that originate from the TTF fragments to the macrocyclic core. The incremental synthetic addition of TTF moieties to the porphyrin core makes the species more susceptible to these charge-transfer (CT) effects as evidenced by spectroscopic studies. On the other hand, regular positive shifts in the reduction signals are seen in the square-wave voltammograms as the number of TTF subunits increases. Structural studies that involve the tetrakis-substituted TTF-porphyrin (both free-base and ZnII complex) reveal only modest deviations from planarity. The effect of TTF substitution is thus ascribed to electronic overlap between annulated TTF subunits rather than steric effects. The directly linked thiafulvalene subunits function as both π acceptors as well as σ donors. Whereas σ donation accounts for the substituent-dependent charge-transfer transitions, it is the π-acceptor nature of the appended tetrathiafulvalene groups that dominates the redox chemistry. Interactions between the subunits are also reflected in the square-wave voltammograms. In the case of the free-base derivatives that bear multiple TTF subunits, the neighboring TTF units, as well as the TTF ⋅+ generated through one-electron oxidation, can interact with each other; this gives rise to multiple signals in the square-wave voltammograms. On the other hand, after metalation, the electronic communication between the separate TTF moieties becomes restricted and they act as separate redox centers under conditions of oxidation. Thus only two signals, which correspond to TTF .+ and TTF2+, are observed. The reduction potentials are also seen to shift towards more negative values after metalation, a finding that is considered to reflect an increased HOMO-LUMO gap. To probe the excited-state dynamics and internal CT character, transient absorption spectral studies were performed. These analyses revealed that all the TTF-porphyrins of this study display relatively short excited-state lifetimes, which range from 1 to 20 ps. This reflects a very fast decay to the ground state and is consistent with the proposed intramolecular charge-transfer effects inferred from the ground-state studies. Complementary DFT calculations provide a mechanistic rationale for the electron flow within the TTF-porphyrins and support the proposed intramolecular charge-transfer interactions and π-acceptor effects. [ABSTRACT FROM AUTHOR]

Abstract: The pyrazole based ditopic ligand PzCAP (HL, 5-methyl-N′-(1-(pyridine-2-yl)ethylidene)-1H-pyrazole-3 carbohydrazide) reacts with Ni(ClO4)2·6H2O, Zn(ClO4)2·6H2O and Cd(ClO4)2·6H2O to form a new alkoxide bridged binuclear Ni(II) complex [Ni2(PzCAP)3](ClO4)3·6(H2O) (1), a mononuclear Zn(II) complex [Zn(PzCAP)2](ClO4)(H2O) (2) and a self assembled pentanuclear Cd(II) complex [Cd5(PzCAP)6](ClO4)4(H2O) (3). These complexes have been characterized crystallographically and spectroscopically. In complex 1, the three ligand molecules display variable denticity towards the Ni(II) centers, one ligand behaves as tetradentate and two others behave as tridentate ligands to create distorted octahedral environments around the two Ni(II) centers, with N5O and N4O2 chromophores. In 2, the same ligand, using keto and enolic oxygen atoms, produces a distorted octahedral environment around the Zn(II) center with a N4O2 chromophore. Complex 3 has a pentanuclear core with a trigonal bipyramidal arrangement of Cd(II) atoms, where the axial metal centers (Cd2 and Cd4) have N3O3 chromophores and the equatorial centers (Cd1, Cd3 and Cd5) have N4O2 chromophores, with distorted octahedral arrangements around the metal centers. Interestingly, the pyrazole unit remains inactive to coordination for complex 2, whereas this unit takes part in coordination for 1 and 3. The ligand HL, complex 2 and complex 3 show fluorescence, while in 1 the fluorescence is substantially quenched compared to the ligand (HL) and its Zn and Cd complexes. As the ligand is capable of using different binding modes, according to the demands of the complex, the emission properties also change accordingly. [Copyright &y& Elsevier]

Abstract: A pyrimidyl-pyrazole based ditopic ligand N-[amino(pyridin-2-yl)methylidene]-1-(4,6-dimethylpyrimidin-2-yl)-5-methyl-1H-pyrazole-3-carbohydrazonic acid, PymPzOAP prepared by the reaction between pyrimidyl pyrazole 3-carbohydrazide and methyl ester of iminopicolinic acid, reacts with Cu(NO3)2·6H2O to form a self-assembled, ferromagnetically coupled alkoxide bridged tetranuclear homoleptic Cu(II)4 [2×2] grid complex [Cu4(PymPzOAP)4](NO3)4 (1). The complex has a central Cu4(μ-OR)4 core involving four ligand molecules. All the Cu(II) centers have N4O2 coordination environment with distorted octahedral geometry. Intramolecular ferromagnetic interaction between Cu(II) centers (J =4.94, S =4/2) is the signature of the molecule. [Copyright &y& Elsevier]

Abstract: A binuclear acylhydrazine bridged Cu(II) complex, [Cu2(L)(NO3)3(H2O)] (1), and an anti-orthogonal binuclear oxovanadium(V) complex, [V2O4(L)2] (2), have been synthesized and characterized spectroscopically and crystallographically. The ligand HL has two potentially bridging functional groups (μ-O, μ-N–N) and consequently can exist in the following coordination conformers: (a) metal centers bridged by μ-O, (b) metal centers bridged by μ-N–N. A rare acylhydrazine bridged (a) type configuration exists in the dinuclear Cu(II) complex 1. The bridging ligand mediates a strong antiferromagnetic coupling (J =−99cm−1). The exchange pathway parameters have also been evaluated from density functional theoretical calculations to corroborate the bridging signatures with experimental findings (J =−93.96cm−1). Molecule 2 has a centrosymmetric structure with each vanadium center having a distorted octahedral geometry. It shows a one step irreversible reduction at +0.43V. The bond angles, bond lengths and torsion angles in 2 are correlated with DFT. [Copyright &y& Elsevier]

Abstract: Two new dinuclear copper(II) complexes [Cu2(PymPz)2(N3)2Cl2] (1), [Cu2(PymPz)2(N3)4] (2) and two new dinuclear cobalt(II) complexes [Co2(PymPz)2Cl4] (3), [Co2(PymPz)2(N3)4] (4) [PymPz=2-(3,5-dimethyl-1H-pyrazol-1-yl)-4,6-dimethylpyrimidine] have been synthesized and characterized crystallographically and spectroscopically. In each of the complexes 1, 2 and 4 the two adjacent metal centers are bridged by a pair of μ-1,1 azide groups whereas in 3 the metal centers are bridged by a pair of chloride ions. In the complexes, all the metal centers are pentacoordinated. In 1 and 2 the copper(II) centers have distorted square pyramidal geometry (τ =0.18 for 1 and 0.091 for 2) but in 3 and 4 cobalt(II) centers have distorted trigonal bipyramidal geometry (τ =0.619 for 3 and 0.557 for 4). Complexes 1 and 2 show antiferromagnetic interaction (J =−7.09cm−1 for 1 and J =−17.00cm−1 for 2) whereas 3 and 4 show ferromagnetic interaction (J =7.44cm−1 for 3 and J =10.45cm−1 for 4). Complex 3 displays an unprecedented ferromagnetic interaction over double μ-chloro bridges in the observed angle range (94.87°). The exchange pathways parameters for all the complexes have also been evaluated from density functional theoretical calculations to corroborate the bridging signatures with experimental findings. [Copyright &y& Elsevier]

Abstract: Varying coordination modes of the Schiff base ligand H2L [5-methyl-1-H-pyrazole-3-carboxylic acid (1-pyridin-2-yl-ethylidene)-hydrazide] towards different metal centers are reported with the syntheses and characterization of four mononuclear Mn(II), Co(II), Cd(II) and Zn(II) complexes, [Mn(H2L)(H2O)2](ClO4)2(MeOH) (1), [Co(H2L)(NCS)2] (2), [Cd(H2L)(H2O)2](ClO4)2 (3) and [Zn(H2L)(H2O)2](ClO4)2 (4), and a binuclear Cu(II) complex, [Cu2(L)2](ClO4)2 (5). In the complexes 1–4 the neutral ligand serves as a 3N,2O donor where the pyridine ring N, two azomethine N and two carbohydrazine oxygen atoms are coordinatively active, leaving the pyrazole-N atoms inactive. In the case of complex 5, each ligand molecule behaves as a 4N,O donor utilizing the pyridine N, one azomethine N, the nitrogen atom proximal to the azomethine of the remaining pendant arm and one pyrazole-N atom to one metal center and the carbohydrazide oxygen atom to the second metal center. The complexes 1–4 are pentagonal bipyramidal in geometry. In each case, the ligand molecule spans the equatorial plane while the apical positions are occupied by water molecules in 1, 3 and 4 and two N bonded thiocyanate ions in 2. In complex 5, the two Cu(II) centers have almost square pyramidal geometry (τ =0.05 for Cu1 and 0.013 for Cu2). Four N atoms from a ligand molecule form the basal plane and the carbohydrazide oxygen atom of a second ligand molecule sits in the apex of the square pyramid. All the complexes have been X-ray crystallographically characterized. The Zn(II) and Cd(II) complexes show considerable fluorescence emission while the remaining complexes and the ligand molecule are fluorescent silent. [Copyright &y& Elsevier]