XRD, thermal, FTIR and SEM studies on gel grown γ-glycine crystals

Reusable Zwitterionic Porous Organic Polymers for Bilirubin Removal in Serum

Herein, we report a straightforward strategy to construct reusable, hemocompatible, and highly efficient bilirubin adsorbents by installing zwitterionic modules into a porous organic polymer (POP) for hemoperfusion application. Three types of zwitterions with different amounts are used to evaluate their impacts on the characteristics of POPs, including carboxybetaine methacrylate (CB), sulfobetaine methacrylate (SB), and 2-methacryloyloxyethyl phosphorylcholine (MPC). Results show that zwitterions can improve hemocompatibility, hydrophilicity, and bilirubin uptake of the POP. Among all zwitterionic POPs, POP-CB-40% exhibits the best bilirubin uptake, ∼46.5 times enhancement compared with the non-zwitterionic POP in 100% serum. This enhancement can be attributed to the improved hydrophilicity and protein resistance ability in biological solutions. More importantly, the reusability test shows that POP-CB-40% maintains ∼99% of bilirubin uptake capacity at fifth recycling in 100% serum. Findings in this work provide a guideline for the design of biocompatible and efficient POP-based bilirubin adsorbents for hemoperfusion therapy.

A new approach for antimicrobial and antiviral activities of biocompatible nanocomposite based on cellulose, amino acid and graphene oxide

In this work, biocompatible, antimicrobial, and antiviral nanocomposites were prepared through two steps. In the first step, periodate oxidation of cellulose was performed to get dialdehyde cellulose (DAC). The second step included the reaction of DAC with sulfur-containing amino acids included Cysteine (Cys) and Methionine (Meth) in the presence of graphene oxide (GO). The prepared nanocomposites were characterized via FT-IR, SEM, TEM, and TGA. Antimicrobial and antiviral activities for all designed nanocomposites besides DAC were carried out. Both DAC/GO/Cys and DAC/GO/Meth exhibited a promising antimicrobial activity against Gram-negative (E. coli and P. aeruginosa), Gram-positive (B. subtilis and S. aureus), and unicellular fungi (C. Albicans and C. neoformans), while the DAC/GO/Cys/Meth nanocomposite was the lowest. Moreover, all designed nanocomposites have a strong antiviral activity against Herpes simplex virus 1(HSV-1) at minimum nontoxic concentration. Additionally, Computational procedures and Molecular docking showed the reactivity and stability of the molecules that have biological activity against Gram-positive, Gram-negative, and HSV-1. As well as DAC incorporation with amino acid enhanced their reactivity and their interaction.

Quasi-Equilibria and Polarization Transfer Between Adjacent and Remote Spins: 1H-13C CP MAS Kinetics in Glycine

The ¹H-¹³C CP MAS kinetic curves were measured in glycine powder sample at the MAS rates of 7, 10, and 12 kHz. Each experimental curve contained up to 1000 equidistant points over the whole contact time range of 10 μs - 10 ms. The CP kinetic data for CH₂ group, i.e., for the system containing adjacent ¹H-¹³C spin pairs with a definite dominant dipolar coupling can be described in the frame of the isotropic spin-diffusion approach. The local order parameter ⟨ S⟩ ≈ 1.0, determined as the ratio of the measured dipolar ¹H-¹³C coupling constant and the calculated static dipolar coupling constant, is very close to the values deduced in series of other amino acids. The strong narrow peaks observed in the spin coupling spectrum at multiples of the MAS frequency can be considered as the confirmation that the periodic quasi-equilibrium state can appear also in the powder samples. The anisotropic spin-diffusion approach improved by the introducing of the thermal equilibration in the proton bath is the most proper model to describe the CP kinetics in the system containing remote spins. Very realistic values of the spin-cluster size ( N) have been obtained without any constraint on the flow of the nonlinear curve fitting. The finite values of N ≤ 4 means that CP transfer is located within one glycine molecule.

Effect of nucleants in photothermally assisted crystallization

Laser-induced crystallization is emerging as a promising technique to crystallize biomolecules like amino acids and proteins. The use of external materials as nucleants and novel seeding methods open new paths for protein crystallization. We report here the results of experiments that explore the effect of nucleants on laser-based crystallization of microlitre droplets of small molecules, amino acids, and proteins. The role of parameters like solute concentration, droplet volume, type and size of the nucleant, and laser power, are systematically investigated. In addition to crystallization of standard molecules like NaCl, KCl, and glycine, we demonstrate the crystallization of negatively (l-histidine), and positively (l-aspartic acid) charged amino acids and lysozyme protein. Single crystal X-ray diffraction and Raman spectroscopy studies unequivocally indicate that the nucleants do not alter the molecular structure of glycine, hydrogen bonding patterns, and packing. Localized vaporization of the solvent near the nucleant due to photothermal heating has enabled us to achieve rapid crystallization - within 3 s - at laser intensities of 0.1 MW cm^-2, significantly lower than those reported earlier, with both saturated and unsaturated solutions. The outcome of the current experiments may be of utility in tackling various crystallization problems during the formation of crystals large enough to perform X-ray crystallography.

Crystal structure of 1,10-phenanthrolinium 3-hy-droxy-2,4,6-tri-nitro-phenolate

In the title molecular salt, C12H9N2 (+)·C6H2N3O8 (-), the cation and anion are connected by an N-H⋯O hydrogen bond. In the anion, an intra-molecular O-H⋯O hydrogen bond with an S(6) ring motif is observed. The planes of two of the nitro groups are approximately parallel to the plane of the benzene ring, making dihedral angles of 3.9 (2) and 15.3 (2)°, while the third nitro group is almost perpendicular to the benzene ring, with a dihedral angle of 78.6 (3)°. In the crystal, cation-anion pairs related by an n-glide plane are connected by C-H⋯O hydrogen bonds, forming a chain structure along [101]. Sensitivity tests and thermal testing indicate that the title salt is an insensitive high-energy-density material (IHEDM).

Synthesis of a new class of carbon-bonded anionic sigma complexes with 1,3-dimethyl-2,6-dioxo-5-(2,4,6-trinitrophenyl)-1,2,3,6-tetrahydropyrimidin-4-olate moiety as insensitive high energy density materials -- implications from impact sensitivity and thermal testings

Background

Poly nitro aromatic compounds are high energy density materials. Carbon–bonded anionic sigma complexes derived from them have remarkable thermal stability. At present there is a strong requirement for thermally stable insensitive high energy density materials (IHEDMs) in the energetic field which necessitates the present investigation.

Results

Three new carbon–bonded anionic sigma complexes were synthesized from 2-chloro-1,3,5-trinitrobenzene, 1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione (1,3-dimethylbarbituric acid) and bases such as triethanolamine, pyridine and N,N-diethylaniline, characterized by UV–VIS, IR, ¹H NMR, ¹³C NMR and elemental analysis data. Their molecular structures were further ascertained through single crystal X-ray diffraction studies. TGA/DTA testings were undertaken at four different heating rates (5, 10, 20 and 40 K/min) and energy of activation was determined employing Ozawa and Kissinger plots.

Conclusions

The reported carbon–bonded anionic sigma complexes were prepared through single pot synthesis in good yield with high purity. These complexes are molecular salts comprise of cation and anion moieties. Because of the salt–like nature, they are highly stable upto 300°C and decompose in two stages on further heating. They are stable towards impact of 2 kg mass hammer upto height limit (160 cm) of the instrument. The delocalization of the negative charge and various hydrogen bonds noticed in their crystals are the added factors of their thermal stability. The new insensitive high energy density materials of the present findings may receive attention in the field of energetics in future.

Graphical Abstract

Effect of KCl addition on crystal growth and spectral properties of glycine single crystals

Glycine usually crystallizes as the metastable alpha-polymorph from pure aqueous solution. The polymorph, gamma-form of glycine can be crystallized only in presence of additive. In the present work, gamma-glycine has been crystallized by using potassium chloride (KCl) as additive at ambient temperature by solvent evaporation method. The form of crystallization is confirmed by X-ray powder diffraction method. Spectroscopic and thermal studies have been carried out for analyzing the presence of functional groups, thermal stability and decomposition of the sample. The results indicate that the KCl is doped into the gamma-glycine. The optical transparency of the gamma-glycine in the ultraviolet-visible region has been studied by recording the optical transmission spectrum. Second harmonic generation (SHG) conversion efficiency has been estimated as 120 mV and the output power by the crystal is less than that of potassium dihydrogen phosphate crystal.