Unique Fluorogenic Ratiometric Fluorescent Chemodosimeter for Rapid Sensing of CN− in Water

A new benzimidazole‐spiropyran conjugate chemosensor molecule ( BISP ) has been synthesized and characterized by ¹H NMR spectroscopy, mass spectrometry (ESI‐MS), and elemental analysis. The two isomeric forms ( BISP ? BIMC ) were shown to be highly selective and sensitive to CN^? among the ten anions studied in aqueous HEPES buffer, as shown by fluorescence and absorption spectroscopy and even by visual color changes, with a detection limit of 1.7 μM for BIMC . The reaction of CN^? with BIMC was monitored by ¹H NMR spectroscopy, high‐resolution mass spectrometry (HRMS), UV/Vis measurements, and fluorescence spectroscopy in HEPES buffer of pH 7.4. TDDFT calculations were performed in order to correlate the electronic properties of the chemosensor with its cyanide complex. Further, titration against thiophilic metal ions like Au³⁺, Cu²⁺, Ag⁺, and Hg²⁺ with [ BIMC‐CN ] in situ showed that it acts as a secondary recognition ensemble toward Au³⁺ and Cu²⁺ by switch‐on fluorescence. In addition, a reversible logic‐gate property of BIMC has been demonstrated through a feedback loop in the presence of CN^? and Au³⁺ ions, respectively. Furthermore, the use of BIMC to detect CN^? in live cells by fluorescence imaging has also been demonstrated. Notably, test strips based on BIMC were fabricated, which could serve as convenient and efficient CN^? test kits.     

Quantification of non-viscous damping in discrete linear systems

The damping forces in a multiple-degree-of-freedom engineering dynamic system may not be accurately described by the familiar ‘viscous damping model’. The purpose of this paper is to develop indices to quantify the extent of any departures from this model, in other words the amount of ‘non-viscosity’ of damping in discrete linear systems. Four indices are proposed. Two of these indices are based on the non-viscous damping matrix of the system. A third index is based on the residue matrices of the system transfer functions and the fourth is based on the (measured) complex modes of the system. The performance of the proposed indices is examined by considering numerical examples.     

Investigation of the micromechanical deformation behavior of styrene–butadiene star block copolymer/polystyrene blends with high‐voltage electron microscopy

The deformation behavior of blends consisting of a styrene–butadiene star block copolymer and a polystyrene homopolymer was studied by high‐voltage electron microscopy with a tensile device. The mechanical properties and micromechanical deformation mechanisms in the star block copolymer/polystyrene blends were directly influenced by their morphology. Although the pure block copolymer deformed in a very unequal manner (because of a thin‐layer‐yielding mechanism) and revealed no local deformation zones, a transition to the formation of crazelike zones was observed in the blends. This transition in the deformation mechanisms was correlated to the abrupt change in the macroscopic strain at break of the injection‐molded specimens. At lower contents of added polystyrene, a craze‐stopping mechanism was observed, whereas the blends with higher polystyrene contents demonstrated crazing like that in pure polystyrene. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1157–1167, 2003     

Sonochemical bromination of acetophenones using p-toluenesulfonic acid-N-bromosuccinimide.

Substituted acetophenones react with N-bromosuccinimide (NBS) and p-toluenesulfonic acid (p-TsOH) in the presence of ultrasound in methanol at 35 +/- 2 degrees C to give alpha-bromoacetophenones in high yield. In the absence of ultrasound the reaction takes place at the boiling point of methanol (65 degrees C) and takes longer time. The reaction does not take place in the absence of p-TsOH thermally or sonically. However the reaction is possible under photochemical conditions in the absence of p-TsOH. The best solvent for the reaction was found to be methanol.     

Structural, spectroscopic, and theoretical elucidation of a redox-active pincer-type ancillary applied in catalysis

Pincer-type ligands are believed to be very robust scaffolds that can support multifarious functionalities as well as highly reactive metal motifs applied in organometallic chemistry, especially in the realm of catalysis. In this paper, we describe the redox and, therefore, noninnocent behavior of a PNP (PNP- = N[2-P(CHMe2)2-4-methylphenyl]2) pincer ancillary bound to nickel. A combination of structural, spectroscopic, and theoretical techniques suggests that this type of framework can house an electron hole when coordinated to Ni(II).     

Cu−NHC Complex for Chan-Evans-Lam Cross-Coupling Reactions of N-Heterocyclic Compounds and Arylboronic Acids

An efficient copper(II) N-heterocyclic carbene (NHC) complex with an NCN coordination mode was optimized to catalyze the Chan–Evans-Lam (CEL) cross-coupling reaction of imidazole and other N-heterocyclic nucleophiles with arylboronic acid. This air-stable copper catalyst shows robust catalytic performance and tolerates a diverse array of functional groups on both the N-nucleophile and arylboronic acid coupling partners in C−N bond forming reactions with up to 95 % yield. Formation of the Cu−NHC complex in situ generated similar catalytic performance for CEL coupling. Alternative metal ions (Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Zn²⁺, Ru²⁺, and Pd²⁺) were also screened in the presence of the NHC precursor as CEL catalysts.     

Adducts of Bicyclic (Alkyl)(Amino)Carbene with ECl3 and Three Electron Reduction Thereof: Syntheses of BICAAC Stabilized E−E Bonded Compounds (E=P,Sb)

The stoichiometric reaction of bicyclic (alkyl)(amino)carbene (BICAAC) with group 15 chlorides, ECl₃ (E=P, Sb) to form the Lewis adducts BICAAC:ECl₃ (E=P ( 1 ), Sb ( 2 )) has been investigated in the present work. The BICAAC smoothly reacts with PPhCl₂ to form [BICAAC:PPhCl₂] which on in-situ two electron reduction with 2 equivalents of KC₈ afforded the phosphinidene complex, BICAAC=P-Ph ( 3 ). Complete dechlorination of the BICAAC-ECl₃ adducts 1 and 2 with 3 equivalents of KC₈ leads to three-electron reduction to afford low-valent trans bent bis(BICAAC)E₂ complexes (E=P ( 4 ) and Sb ( 5 )). These complexes are the first examples of BICAAC adducts with pnictogens and all the complexes have been characterized by different spectroscopic techniques and their solid-state structure have been elucidated by single crystal X-ray diffraction.     

P=N bond formation via incomplete N-atom transfer from a ferrous amide precursor

Incomplete N-atom transfer from Fe to P is observed when the ferrous amide complex (PNP)Fe(dbabh) (PNP-=N[2-P(iPr)2-4-methylphenyl]2, dbabh=2,3:5,6-dibenzo-7-azabicyclo[2.2.1]hepta-2,5-diene), prepared from salt metathesis of (PNP)FeCl and Li(dbabh), is thermolyzed at 70 degrees C over 48 h in C6D6. Several plausible reaction pathways resulting from the transformation of (PNP)Fe(dbabh) are discussed, including the possibility of an Fe(IV) nitride as an intermediate.     

Microstructure Measurement Techniques for Studying Electromigration in ULSI Interconnects

Electromigration reliability remains a major threat to microelectronic circuits. Microstructure of a thin film conductor used in integrated circuit affects the electromigration lifetime significantly. A wealth of knowledge is acquired on thin film microstructure and electromigration in metallic interconnects from relevant studies in past few decades. However, it is noticed that the various techniques to measure microstructure-related attributes of thin film metallization are not presented in the context of electromigration, since these measurement techniques have their own importance. On the other hand, aggressive scaling of interconnect line-width down to nano regime, poses new challenges to microstructure characterization techniques. This article connects these two aspects of electromigration study, e.g., the characterization of microstructure and measurement techniques for the influential microstructural attributes especially for Cu-based interconnects. The microstructure-related parameters, attributes, and their impacts on electromigration lifetime are discussed. The sample preparation and various techniques to measure attributes of microstructure are presented in detail. This article describes the current state-of-the-art for the advancement of studying microstructure dependent electromigration reliability.     

Magical Allotropes of Carbon: Prospects and Applications

The invention of carbon and its allotropes have transformed the electronic and optoelectronic industry due to their encouraging properties in a large spectrum of applications. The interesting characteristic of carbon is its ability to form many allotropes due to its valency. In recent decades, various allotropes and forms of carbon have been invented, including fullerenes, carbon nanotubes (CNTs), and graphene (GR). Since the inception of nanotechnology, carbon allotropes-based nanocomposites have become a leading sector of research and advancement due to their unique bonding properties. Fullerenes and CNTs-based polymer nanocomposites have attracted significant research interest due to their vast applications in every sphere of science and technology. Current research impetus reveals that carbon and its allotropes have revolutionized the industry and academia due to their fascinated properties. Recent advances in various aspects of graphene, CNTs, graphene nanoribbons, fullerenes, carbon encapsulates, and their nanocomposites with polymeric materials and their different applications are reported in this review article. Also, current status and future prospects of graphene-based polymer nanocomposites are presented in common along with proper citations extracted from the scientific literature. Moreover, this article is a unique collection of vital information about GR, CNTs, fullerenes, and graphene-based polymer nanocomposites in a single platform.