The Quest for Molecular Grippers: Photo-Electric Control of Molecular Gripping Machinery

The quest for nanoscale molecular machines has inspired the search for their close relatives, molecular grippers. This path was paved by the development of resorcin[4]arene cavitands and their quinone-based redox-active congeners. In this Concept article, the efforts to design and establish the control of quinone-functionalized resorcin[4]arenes by electronic and electromagnetic stimuli is described. This was achieved by relying on paramagnetic semiquinone radical anions formed electrochemically or by photoredox catalysis. The gripper-like motion of such species could not be studied by conventional NMR spectroscopy. Instead, an entirely different approach had to be developed that included various electroanalytical and spectroelectrochemical methods, including UV/Vis/NIR spectroelectrochemistry, pulsed EPR and Davies ¹H ENDOR spectroscopy, transient absorption spectroscopy, and time-resolved luminescence measurements, besides density functional theory calculations and X-ray crystallography. The conceptual breakthroughs are reviewed as well as the current state and future perspectives of photoredox-switchable molecular grippers.     

Radiological,structural and chemical characterization of raw materials and ceramic tiles in Serbia

Journal of Radioanalytical and Nuclear Chemistry - This paper presents the results of the gamma spectrometric analysis of 27 raw materials used for the production of ceramic tiles in Serbia and 9...     

The Rise of Dye-Sensitized Solar Cells: From Molecular Photovoltaics to Emerging Solid-State Photovoltaic Technologies

Over the past three decades, dye-sensitized solar cells (i. e. Grätzel cells) have evolved from a pioneering concept of molecular photovoltaics to large-scale industrial deployment. In this review article, we provide a historical overview of the developments with a focus on the scientific advancements that have set the stage for this technology to emerge and thrive. This involves insights into the (photo)electrochemistry of the underlying processes, molecular engineering of dyes, redox shuttles, and hole-transporting materials, as well as their implementation into solar cells. We further outline applications and future perspectives, involving the long-lasting objective to develop efficient solid-state alternatives to conventional dye-sensitized solar cells.     

Chalcogen Bonding “2S–2N Squares” versus Competing Interactions: Exploring the Recognition Properties of Sulfur

Chalcogen bonding (CB) is the focus of increased attention for its applications in medicinal chemistry, materials science, and crystal engineering. However, the origin of sulfur's recognition properties remains controversial, and experimental evidence for supporting theories is still emerging. Here, a comprehensive evaluation of sulfur CB interactions is presented by investigating 2,1,3-benzothiadiazole X-ray crystallographic structures gathered from the Cambridge Structure Database (CSD), Protein Data Bank (PDB), and own laboratory findings. Through the systematic analysis of substituent effects on a subset library of over thirty benzothiadiazole derivatives, the competing interactions have been categorized into four main classes, namely 2S–2N CB square, halogen bonding (XB), S ⋅⋅⋅ S, and hydrogen-bonding (HB). A geometric model is employed to characterize the 2S–2N CB square motifs and discuss the role of electrostatic, dipole, and orbital contributions toward the interaction.     

Radioactivity of building materials in Serbia and assessment of radiological hazard of gamma radiation and radon exhalation

Journal of Radioanalytical and Nuclear Chemistry - This paper presents a gamma spectrometric analysis of 47 samples of building materials produced and used in Serbia. Based on the measured activity...     

On optimal fourth-order iterative methods free from second derivative and their dynamics

In this paper new fourth order optimal root-finding methods for solving nonlinear equations are proposed. The classical Jarratt’s family of fourth-order methods are obtained as special cases. We then present results which describe the conjugacy classes and dynamics of the presented optimal method for complex polynomials of degree two and three. The basins of attraction of existing optimal methods and our method are presented and compared to illustrate their performance.     

Study on quench effects in liquid scintillation counting during tritium measurements

Quench effects can cause a serious reduction in counting efficiency for a given sample/cocktail mixture in liquid scintillation counting (LSC) experiments. This paper presents a simple experiment performed in order to test the influence of quenching on the LSC efficiency of ³H. The aim of this study was to investigate the behavior of several quench agents with different quench strengths (nitromethane, nitric acid, acetone, dimethyl-sulfoxide) added in different amounts to tritiated water in order to obtain standard sets for quench calibration curves. The OptiPhase HiSafe 2 and OptiPhase HiSafe 3 scintillation cocktails were used in this study in order to compare their quench resistance. Measurements were performed using a low-level LS counter (Wallac, Quantulus 1220).     

A note on the perturbation bounds of W-weighted Drazin inverse

We investigate the perturbation bound for the W-weighted Drazin inverse of a rectangular matrix and present two explicit expressions for the W-weighted Drazin inverse under the one-sided condition, which extends the results in Appl. Math. Comput. 2004;149:423–430.     

Differentiation of black,green, herbal and fruit bagged teas based on multi-element analysis using inductively-coupled plasma atomic emission spectrometry

In the present paper, multi-element characterisation of 26 bagged teas was carried out using inductively-coupled plasma atomic emission spectrometry. Na, K, Ca and Mg were the metals with major contents. Among the essential elements, Fe and Zn were the most abundant, followed by Se, Cu, Mo and Cr. The tea bag samples also contained significant contents of Mn and Al. The chemometric techniques of linear correlation analysis, principal component analysis (PCA) and cluster analysis (CA) were used for differentiation of the tea bag samples according to their metal content. The samples analysed were classified into four groups by PCA and CA. The first group includes hibiscus, nettle, mint, rtanj tea, thyme, bearberry and sage. Green and black teas are in the second group. The third group contains strawberry, lime, pineapple, pomegranate, elder, blueberry, milfoil, apricot and chamomile. Exotic fruits, sweet cherry, forest fruits, apple, St John’s wort, rose hips, cherry and raspberry are in the fourth group.