Forecast of Phase Diagram for the Synthesis of a Complex for the Detection of Cr6+ Ions.

A new organic complex (ANNBA) was synthesized using the solvent-free, solid-state reaction involving anthranilamide (AN)-m-nitrobenzoic acid (NBA). The established phase diagram specifies the formation of a complex in a 1:1 stoichiometric ratio which melts congruently at 142 °C. The diagram also infers the formation of two eutectics, E1 and E2, on either side of the complex with their respective melting at 118 and 106 °C. The stability and novelty of the synthesized complex was confirmed by differential scanning calorimetry, powder X-ray diffraction, and spectroscopic FTIR, 1H, and 13C NMR studies. The significant thermodynamic parameters such as the heat of mixing, the entropy of fusion, the roughness parameter, the interfacial energy, and excess thermodynamic functions have been studied. The novel complex (ANNBA) material displayed intense fluorescent emission as compared to the parent and the other well-known fluorescent organic material "pyrene." The influence of solvent's polarity on the absorption and emission of the complex has been studied in different solvents. Herein, we have displayed remarkable affinity of the complex toward hexavalent chromium ions in water, affecting its fluorescent property. We have deployed the synthesized complex as a turn-off fluorescent sensor to detect the most hazardous hexavalent chromium ions in water for the first time.

Probing short and long-range interactions in native collagen inside the bone matrix by BioSolids CryoProbe.

Solid-state nuclear magnetic resonance is a promising technique to probe bone mineralization and interaction of collagen protein in the native state. However, many of the developments are hampered due to the low sensitivity of the technique. In this article, we report solid-state nuclear magnetic resonance (NMR) experiments using the newly developed BioSolids CryoProbe™ to access its applicability for elucidating the atomic-level structural details of collagen protein in native state inside the bone. We report here approximately a fourfold sensitivity enhancement in the natural abundance 13 C spectrum compared with the room temperature conventional solid-state NMR probe. With the advantage of sensitivity enhancement, we have been able to perform natural abundance 15 N cross-polarization magic angle spinning (CPMAS) and two-dimensional (2D) 1 H-13 C heteronuclear correlation (HETCOR) experiments of native collagen within a reasonable timeframe. Due to high sensitivity, 2D 1 H/13 C HETCOR experiments have helped in detecting several short and long-range interactions of native collagen assembly, thus significantly expanding the scope of the method to such challenging biomaterials.

Water-lipid interactions in native bone by high-resolution solid-state NMR spectroscopy.

The study of structural and dynamical properties of lipid and its associated interaction with different components of bone is essential to understand its role at a different level of bone homeostasis such as bone mineralization and bone metabolism. In this article, we present water-dependent dynamical changes observed in lipids (triglycerides) in its absolute native environment inside bone by high-resolution 1H solid-state nuclear magnetic resonance spectroscopy (ssNMR). Relaxation measurement (T2 measurement) ssNMR experiments were performed at different levels of water network induced by dehydration and H/D exchange in native bone. Our measurements reflect the changes in the local environment and dynamical properties of triglyceride due to different hydration levels. The present study explains the role of water in stabilizing the structural properties of triglycerides in bone hence will help understand its pathological role associated with bone physiology and bone disorders.