Raman and infrared spectra, normal coordinate analysis and ab initio calculations of 4-Amino-2-chloropyrimidine-5-carbonitrile

Vibrational assignments, normal coordinates analysis, force constants, and DFT/MP2 computations of 5-Chloro-2,4,6-trifluoropyrimidine

The vibrational assignments of 5-Chloro-2,4,6-trifluoropyrimidine have been early investigated, however, the proposed fundamentals were not spanned to their appropriate species owing to neglecting the overall symmetry. Nevertheless, the lack of force constants (FCs) determination encourages us to reinvestigate the molecule. Aided by DFT (B3LYP, B3P86, B3PW91, ωBX97) and MP2 = full quantum chemical computations, we have provided a reliable vibrational analysis of all normal modes based on the C2v point group. Different methods of the currently used normal coordinate analysis were also validated. Our results are compared with available infrared and Raman spectral data, including estimated infrared intensities, Raman scattering activities, genuine FCs in internal coordinates, and potential energy distributions (PEDs). Using NCA in a well-defined internal coordinate that enables us to estimate FCs based on G.F. Wilson led to better fundamental interpretations than those obtained from atomic displacements in Cartesian coordinates, VEDA, and MOLVIB programs. The current investigation potentially offers corrected vibrational mode assignments, filling gaps in prior literature and aiding in accurately characterizing fluorinated pyrimidine derivatives.

Anti-Wrinkle and Dyeing Properties of Silk Fabric Finished with 2,4,6-Trichloropyrimidine

Silk, a natural protein fiber, is widely used in the textile industry and biomedical materials for its excellent properties. However, its application in some fields is seriously restricted due to its poor anti-wrinkle behavior. In this study, 2,4,6-trichloropyrimidine (TLP) was used in the production of anti-wrinkle silk fabrics. The optimum finishing conditions were as follows: 3-g/L 2,4,6-trichloropyrimidine, 6-g/L NaHCO3, 8-g/L Na2SO4, finishing temperature of 65 °C, and finishing time of 40 min. The crease recovery angle of the finished fabric is 16–20% higher than the unfinished fabric, and the finishing process has a small effect on the whiteness of silk while achieving some degree of washing resistance. The morphology and chemical structures of the finished silk fabric were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The K/S value of the finished silk fabric dyed with reactive dyes increased compared with the silk fabric only dyed, indicating that the dyeability of the finished fabric was improved. This technology provides a new method for fabricating silk color crease-resistant fabrics.

Durable Antipilling Modification of Cotton Fabric with Chloropyrimidine Compounds

Cotton fabric, a natural cellulose material, is widely used in the textile industry for its excellent properties. However, its application in some fields are seriously restricted because of its poor antipilling behavior. In this study, cotton fabrics were modified with 2,4,6-trichloropyrimidine (TLP), 2,4-dichloro-5-methoxypyrimidine (DMP), and 2-amino-4,6-dichloropyridine (ADP). The surface morphology and chemical structure of the modified cotton fabric were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Furthermore, the antipilling behavior, dyeing properties, thermal properties, and mechanical properties of modified cotton fabric were evaluated. The results showed that chloropyrimidine compounds were successfully grafted onto the surface of the cotton fabric, leading to excellent and durable antipilling activity of grade 3-4 even after 10 washes. Moreover, compared with control cotton fabric, the heat release rate (HRR) and total heat release (THR) of TLP-modified cotton fabric decreased to 173.2 W/g (42.3% reduction) and 11.3 KJ/g (13.7% reduction), respectively. In addition, the increased K/S value of modified cotton fabrics dyed with reactive dyes indicated that the modification can enhance the dyability of cotton fabric. This technique provides a simple and versatile method for improving the antipilling behavior of cellulosic materials and supports further preparation of functional textiles.

Enhancing adsorption capacity while maintaining specific recognition performance of mesoporous silica: a novel imprinting strategy with amphiphilic ionic liquid as surfactant

In order to facilitate the broad applications of molecular recognition materials in biomedical areas, it is critical to enhance their adsorption capacity while maintaining their excellent recognition performance. In this work, we designed and synthesized well-defined peptide-imprinted mesoporous silica (PIMS) for specific recognition of an immunostimulating hexapeptide from human casein (IHHC) by using amphiphilic ionic liquid as the surfactant to anchor IHHC via a combination of one-step sol-gel method and docking oriented imprinting approach. Thereinto, theoretical calculation was employed to reveal the multiple binding interactions and dual-template configuration between amphiphilic ionic liquid and IHHC. The fabricated PIMS was characterized and an in-depth analysis of specific recognition mechanism was conducted. Results revealed that both adsorption and recognition capabilities of PIMS far exceeded that of the NIMS's. More significantly, the PIMS exhibited a superior binding capacity (60.5 mg g^-1), which could increase 18.9% than the previous work. The corresponding imprinting factor and selectivity coefficient could reach up to 4.51 and 3.30, respectively. The PIMS also possessed lickety-split kinetic binding for IHHC, where the equilibrium time was only 10 min. All of these merits were due to the high surface area and the synergistic effect of multiple interactions (including hydrogen bonding, π-π stacking, ion-ion electrostatic interactions and van der Waals interactions, etc) between PIMS and IHHC in imprinted sites. The present work suggests the potential application of PIMS for large-scale and high-effective separation of IHHC, which may lead to their broad applications in drug/gene deliver, biosensors, catalyst and so on.

FT-IR and FT-Raman spectra of 5-chlorocytosine: Solid state simulation and tautomerism. Effect of the chlorine substitution in the Watson-Crick base pair 5-chlorodeoxycytidine-deoxyguanosine

The laser Raman and IR spectra of 5-chlorocytosine have been recorded and accurately assigned in the solid state using Density functional calculations (DFT) together with the linear scaling equation procedure (LSE) and the solid state simulation of the crystal unit cell through a tetramer form. These results remarkably improve those reported previously by other authors. Several new scaling equations were proposed to be used in related molecules. The six main tautomers of the biomolecule 5-chlorocytosine were determined and optimized at the MP2 and CCSD levels, using different basis sets. The relative stabilities were compared with those obtained in cytosine and their 5-halo derivatives. Several relationships between energies, geometric parameters and NBO atomic charges were established. The effect of the chlorine substitution in the fifth position was evaluated through the stability of the Watson-Crick (WC) base pair of 5-chlorodeoxycytidine with deoxyguanosine, and through their vibrational spectra.