Structural, spectroscopic and NLO features of the 4-chloro-1-naphthol

Experimental and theoretical investigations on a furan-2-carboxamide-bearing thiazole: synthesis, molecular characterization by IR/NMR/XRD, electronic characterization by DFT, Hirshfeld surface analysis and biological activity

A thiazole-based heterocyclic amide, namely, N-(thiazol-2-yl)furan-2-carboxamide, C8H6N2O2S, was synthesized and investigated for its antimicrobial activity. The structure was characterized by elemental analysis and IR, 1H NMR, and 13C NMR spectroscopy. The molecular and electronic structures were investigated experimentally by single-crystal X-ray diffraction (XRD) and theoretically by density functional theory (DFT) modelling. The compound crystallized in the monoclinic space group P21/n and the asymmetric unit contains two symmetrically independent molecules. Several noncovalent interactions were recorded by XRD and analysed with Hirshfeld surface analysis (HSA) calculations. Natural bond orbital, molecular electrostatic potential, second-order nonlinear optical and thermodynamic property analyses were also carried out using the DFT/B3LYP method. The title compound was evaluated for antimicrobial activity against eight microorganisms consisting of Gram-negative bacteria, Gram-positive bacteria and fungi. The compound showed good antimicrobial activity against the eight tested microorganisms. This suggests that the compound merits further study for potential pharmacological and medical applications.

1-Naphthols as components for multifunctional material systems (MFMS): the molecular modeling approach

Increasing research interests have been paid to developing efficient multifunctional material systems (MFMS) by using various composite materials, owing to their useful properties and good stability. Here, we systematically studied 1-naphthols, especially how the type and position of a substituent influence the reactivity and properties, using different electron-directing groups. During computations, important preparation guidelines for thiol derivatives of 1-naphthol were obtained. It is very interesting to note that some molecules could exhibit intramolecular O–H–O interactions. Careful theoretical investigation reveals that all the tested compounds are stable and the molecules with substituents in positions 4 and 8 are the least reactive. It is also worth noting that for the stability and polarizability tensor values, it is more favorable when both substituents are in the same benzene ring. Among tested 1-naphthols, the greatest values of alpha, beta, and gamma are more than 5, 60, and 110 times better respectively, than in the urea molecule; the change of electron-withdrawing group (EWG) to electron-donating group (EDG) increases NLO effects. This study provided a new scope of 1-naphthols applicability by using them as anti-corrosion materials and as very good materials for NLO devices due to the high stability of the aromatic structure coupled with polarity given by the substituents. Also, the understanding of IR vibrations for more complex organic compounds with thiol substituent has been improved.

Non-linear optical properties of polystyrene and polyvinyl alcohol composites with 4-methoxy-1-naphthol

The analysis of the NLO properties of 4-methoxy-1-naphthol (4M1N) reveals that this molecule has the value of polarizability tensor, α, more than 340% greater than that obtained, at the same level of theory, for urea molecule. This improvement grows to 500% when the second-order hyperpolarizability is considered. Calculations performed within LR-PCM-B3LYP/6-311+G(3d,2p) model proved that embedding of 4M1N in the polymer matrix significantly improved these results suggesting applications of 4M1N as the cheap and effective NLO material. The molecule was also studied, both theoretically and experimentally, to determine its full vibrational characterisation and structural description. Calculations were performed with HF, MP2, SVWN and B3LYP methods, in two, varying in size, basis sets, to find optimized structures, conformational isomers and UV–VIS, IR and Raman spectra. The accordance of simulated oscillation and absorption spectra with experimental ones is very good; IR values are slightly red-shifted. NBO charge distribution analysis was made to generate frontier orbitals and find most reactive parts of the molecule.