Complexation of C-Functionalized Cyclams with Copper(II) and Zinc(II): Similarities and Changes When Compared to Parent Cyclam Analogues

Herein, we report a comprehensive coordination study of the previously reported ligands <b>cyclam</b>, <b>CB-cyclam TMC</b>, <b>DMC</b>, <b>CB-DMC</b>, and of their <i>C</i>-functional analogues, <b>cyclam-E</b>, <b>CB-cyclam-E</b>, <b>TMC-E</b>, <b>DMC-E</b> and <b>CB-DMC-E</b>. This group of ligands includes <b>cyclam</b>, cross-bridged <b>cyclams</b>, their di- or tetramethylated derivatives and the analogues bearing an additional hydroxyethyl group on one β-N position of the ring. These Cu(II) and Zn(II) complexes of these macrocycles have been highlighted previously for the biological interest, but the details of their structures in the solid state and in solution remained largely unexplored. <br>

Complexation of C-Functionalized Cyclams with Copper(II) and Zinc(II): Similarities and Changes When Compared to Parent Cyclam Analogues

Herein, we report a comprehensive coordination study of the previously reported ligands <b>cyclam</b>, <b>CB-cyclam TMC</b>, <b>DMC</b>, <b>CB-DMC</b>, and of their <i>C</i>-functional analogues, <b>cyclam-E</b>, <b>CB-cyclam-E</b>, <b>TMC-E</b>, <b>DMC-E</b> and <b>CB-DMC-E</b>. This group of ligands includes <b>cyclam</b>, cross-bridged <b>cyclams</b>, their di- or tetramethylated derivatives and the analogues bearing an additional hydroxyethyl group on one β-N position of the ring. These Cu(II) and Zn(II) complexes of these macrocycles have been highlighted previously for the biological interest, but the details of their structures in the solid state and in solution remained largely unexplored. <br>

Effects of Modifying Thioflavin T at the N3-Position on Its G4 Binding and Fluorescence Emission

We previously synthesized thioflavin T (ThT) with a hydroxyethyl group introduced at the N3-position (ThT-HE), which binds predominantly to the parallel G-quadruplex (G4) structure found in c-Myc and emits strong fluorescence. In this study, to investigate the effects of introduced substituents on G4 binding and fluorescence emission, a ThT derivative in which the hydroxyl group of ThT-HE was replaced with an amino group (ThT-AE) was synthesized for the first time. Furthermore, three other N3-modified ThT derivatives (ThT-OE2, ThT-SP, and ThT-OE11) having different substituent structures were synthesized by the N-acylation of the terminal amino group of ThT-AE, and their G4-binding and emission properties were investigated. The results showed that, although ThT-AE shows binding selectivity depending on the type of G4, its emission intensity is significantly decreased as compared to that of ThT-HE. However, ThT-OE11, which features an 11-unit oxyethylene chain attached to the terminal amino group of ThT-AE, regained about one-half of the emission intensity of ThT-HE while retaining selectivity for G4s. Accordingly, ThT-OE11 may be used as a key intermediate for synthesizing the conjugates of G4 binders and probes.

Regiocontrolled Synthesis of 6,7-Dihydro-4H-pyrazolo[5,1-c][1,4]oxazines

Synthetic access to 6,7-dihydro-4H-pyrazolo[5,1-c][1,4]oxazines has been achieved in 3–4 steps from commercially available pyrazoles. Optimization of a protected hydroxyethyl group on N1 enabled the regiocontrolled construction of pyrazole-5-aldehydes in high yields; subsequent deprotection and reduction generated fused heterocyclic scaffolds bearing multiple substitution patterns. Moreover, the intermediate pyrazole lactols were shown to be versatile synthetic building blocks.

3,3-Bis(2-hydroxyethyl)-1-(4-methylbenzoyl)thiourea: crystal structure, Hirshfeld surface analysis and computational study

In the title tri-substituted thiourea derivative, C13H18N2O3S, the thione-S and carbonyl-O atoms lie, to a first approximation, to the same side of the molecule [the S—C—N—C torsion angle is −49.3 (2)°]. The CN2S plane is almost planar (r.m.s. deviation = 0.018 Å) with the hydroxyethyl groups lying to either side of this plane. One hydroxyethyl group is orientated towards the thioamide functionality enabling the formation of an intramolecular N—H...O hydrogen bond leading to an S(7) loop. The dihedral angle [72.12 (9)°] between the planes through the CN2S atoms and the 4-tolyl ring indicates the molecule is twisted. The experimental molecular structure is close to the gas-phase, geometry-optimized structure calculated by DFT methods. In the molecular packing, hydroxyl-O—H...O(hydroxyl) and hydroxyl-O—H...S(thione) hydrogen bonds lead to the formation of a supramolecular layer in the ab plane; no directional interactions are found between layers. The influence of the specified supramolecular interactions is apparent in the calculated Hirshfeld surfaces and these are shown to be attractive in non-covalent interaction plots; the interaction energies point to the important stabilization provided by directional O—H...O hydrogen bonds.

Microwave-Assisted Kabachnik–Fields Reaction with Amino Alcohols as the Amine Component

In this paper, the microwave (MW)-assisted catalyst-free and mostly solvent-free Kabachnik–Fields reaction of amino alcohols, paraformaldehyde, and various >P(O)H reagents (dialkyl phosphites, ethyl phenyl-H-phosphinate, and secondary phosphine oxides) is reported. The synthesis of N-2-hydroxyethyl-αaminophosphonate derivatives was optimized in respect of the temperature, the reaction time, and the molar ratio of the starting materials. A few by-products were also identified. N,NBis(phosphinoylmethyl)amines containing a hydroxyethyl group were also prepared by the double Kabachnik–Fields reaction of ethanolamine with an excess of paraformaldehyde and secondary phosphine oxides. The crystal structure of a 2-hydroxyethyl-α-aminophosphine oxide and a bis(phosphinoylmethyl)ethanolamine was studied by X-ray analysis.

The Radiostability of Meropenem Trihydrate in Solid State

The influence of ionising radiation on the physicochemical properties of meropenem trihydrate in solid state was studied for doses of e-beam radiation: 25 kGy and 400 kGy. In the first part of our studies, we evaluated the possibility of applying radiosterilization to obtain sterile meropenem. No changes for meropenem irradiated with a dose of 25 kGy, the dose required to attain sterility, was confirmed in the results of spectroscopic (FT-IR), thermal (DSC, TGA) and X-ray powder diffraction (XRPD) studies. The radiation dose of 25 kGy produces no more than about 1500 ppm of radical defects. The chromatographic studies of irradiated meropenem in solutions did not show any chemical degradation. Moreover, the antimicrobial activity of meropenem irradiated with the dose of 25 kGy was unchanged. Based on the received results, we can conclude that radiostelization is a promising, alternative method for obtaining sterile meropenem. In the second part of the research, meropenem was exposed to e-beam radiation at the 400 kGy dose rate. It was confirmed, that reducing of antimicrobial activity could be connected with the degradation of β-lactam ring and changes in the trans-hydroxyethyl group. Apart from chemical changes, changes in the physical stability of irradiated meropenem (400 kGy) was also observed.