Search Results (19)

This study investigates how different substituents modulate the electronic structure and optical properties of seven derivatives of Pyrimidine-benzoxazole (FB.01) in DMSO, aiming to optimize their performance as deep bioimaging probes. The π-conjugated FB.01 core was functionalized with methyl, phenyl, N-oxide, exocyclic phenyl, carboxyl, N(OH)₂, and pyridine. Geometry optimizations were performed using DFT (B3LYP/6-311+G(d,p) with SMD), followed by analysis of frontier orbitals, electronegativity, hardness, and total energy. TD-DFT and the Sum-Over-States approach simulated molar absorptivity spectra and two-photon absorption cross-sections. Results show that minor torsions influence optical responses: the FB.01 skeleton remains nearly planar, though substituents alter π-overlap and shift the LUMO, while the HOMO stays at −7.65 eV. N-oxide and carboxyl groups stabilize the LUMO, narrowing the energy gap (down to 5.20 eV in FB.04 and 6.07 eV in FB.06), whereas methyl widens it (6.38 eV). All compounds preserve a strong UV-band; conjugation increases absorptivity, and FB.04 exhibits a 31 nm red-shift. TPA grows with conjugation and peaks dramatically in FB.04 (23 GM), surpassing other derivatives. These findings highlight three design principles: strong acceptors like N-oxide effectively lower the LUMO and enhance TPA; additional aromatic rings boost one-photon absorption; and carboxyl or N(OH)₂ groups finely tune polarity without disrupting planarity. Full article

Azole selenoureas exhibit diverse biological functions. However, the synthesis and biological activity of benzothiazole and benzoxazole selenones remained unexplored. Herein, we report the base-catalyzed synthesis of N-difluoromethyl benzothiazole (or benzoxazole) selenone derivatives, which demonstrated significant antifungal efficacy against Rhizoctonia solani, Phytophthora infestans, Botrytis cinerea, and Fusarium oxysporum. Compound 3b exhibited exceptional antifungal activity against R. solani, with an EC₅₀ of 2.10 mg/L. Moreover, it substantially inhibited sclerotia germination (81.5% at 9 mg/L) and formation (79.3% at 9 mg/L), surpassing octhilinone. The protective effect on detached rice leaves and rice seedlings was found to be 43.4% and 85.2% at 100 mg/L, respectively, and 64.4% and 89.4% at 200 mg/L. These findings suggest that benzothiazole and benzoxazole selenones represent promising lead compounds for sustainable plant disease management. Full article

Benzoxazoles are recognized as significant building blocks in organic synthesis and materials science. This work observed the formation of benzoxazole from o-aminophenol and o-hydroxybenzaldehyde using online ¹H NMR (continuous flow cell, 80 MHz). The identification of changes in the functional group was complemented by ATR-FTIR analysis. Additionally, the kinetic roles of phenylboronic acid and cyanide in the one-pot condensation-cyclization reaction are examined. Real-time monitoring has revealed three observable events: the rapid condensation of the aldehyde and o-aminophenol to produce the imine; the formation of the boron complex in the presence of phenylboronic acid; and the cyanide-assisted cyclization that converts the intermediate into benzoxazole. The findings clarify the transformations that control throughput and provide valuable insights for optimizing reagent loadings under environmentally friendly conditions. Full article

This theoretical work investigates the linear (absorption and emission) and nonlinear (first hyperpolarizability and TPA) optical properties of donor–$\pi$–acceptor (D–$\pi$–A) molecular architectures based on functionalized benzoxazoles, with potential applications in optoelectronic technologies such as OLEDs and solar cells. Four $\pi$-conjugated compounds were studied in the gas phase and in polar (methanol) and nonpolar (toluene) solvents, employing DFT with the B3LYP and CAM-B3LYP functionals and the 6-311++G(d,p) basis set, as implemented in Gaussian and Dalton. The results reveal that the chemical environment induces spectral shifts and modulates the intensity of electronic transitions. In particular, the compound 2-((4-((5-nitro-2-oxo-1,3-benzoxazol-3(2H)-yl)amino)phenyl)methyl)-1,3-benzoxazole exhibited outstanding behavior in methanol, with a significant increase in dipole moment, polarizability, and first hyperpolarizability (static and dynamic at 1064 nm), reaching a TPA cross-section close to 150 GM. These findings highlight the key role of ionic substituents in tuning the optical response of $\pi$-conjugated systems and underscore their potential as functional materials for high-performance light-emitting and energy-conversion devices. Full article

This study explores the corrosion inhibition of C38 steel in a 1 M hydrochloric acid (HCl) solution using a novel benzoxazole-2-thione compound. The inhibitor was synthesized and structurally characterized by both ¹H NMR (DMSO-d₆/TMS) and ¹³C NMR spectroscopy. Electrochemical techniques, including Tafel polarization and electrochemical impedance spectroscopy, were employed to evaluate the inhibition performance. The results indicate that the benzoxazole-2-thione significantly reduces the corrosion rate, achieving a maximum inhibition efficiency of 95.25% at a concentration of 10⁻⁴ M. To gain deeper insights into the inhibition mechanism, theoretical methods such as density functional theory, Monte Carlo simulations, and molecular dynamics were applied to investigate the adsorption behavior of the compound on the steel surface. The adsorption process follows the Langmuir isotherm model, suggesting the coexistence of physisorption and chemisorption interactions. Surface morphology and elemental composition analyses using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX) confirm the formation of a protective inhibitor film on the steel surface. Full article

We report a method for the synthesis of 2-substituted benzoxazoles from tertiary amides and 2-aminophenols in the presence of triflic anhydride (Tf₂O) and 2-Fluoropyridine (2-F-Pyr). The cascade reaction involves the activation of the amide carbonyl group by Tf₂O, nucleophilic addition, intramolecular cyclization, and elimination. Furthermore, we explore the scope of this method by varying both the amide and 2-aminophenol substrates, highlighting its versatility in the synthesis of a wide range of functionalized benzoxazole derivatives. Full article

The six stilbene-based dyes containing benzoxazole substituents to improve solubility of dyes as well as the efficiency of fluorescence at blue emission were synthesized. In this work, absorption and fluorescent properties of the synthesized dyes were investigated. For the derivatization of benzoxazolyl stilbene dye, -NO₂ and -NH₂ groups were introduced in sequence onto benzoxazolyl rings. The emission maxima of the six dyes prepared were observed in the range of 435 nm~471 nm. In addition, the solubility of the dyes in dichloromethane was examined for application to the nonpolar polymer films such as PE, PP, PVC and so on. N-alkyl groups were determined to have a greater solubility of alkylated stilbene-based dyes than analogue containing and unsubstituted group. Furthermore, investigation of the optical effects of tortional strain according to conformation of side group was also performed. For identifying these properties, the geometry, dihedral angle, and other parameters of synthesized dyes were calculated by the density functional theory and time-dependent function using a gaussian 09 program. Full article

An efficient and convenient synthesis of benzoxazole/benzothiazole-substituted esters in a one-pot strategy is reported. In this investigation, a selective construction of C-N and C-S bonds via simple addition is performed. Thus, using substituted 2-aminophenols/2-aminobenzenethiols, TMTD (tetramethylthiuram disulfide) and α,β-unsaturated esters as starting substrates, C-N and C-S bonds can be selectively constructed by means of the Michael addition reaction. This protocol features high selectivity, high atomic economy, mild conditions, good functional tolerance and good to excellent yields, showing the potential value for the preparation of some biologically and pharmaceutically active compounds. Full article

Damage to intervertebral discs (IVD) can lead to chronic pain and disability, and no current treatments can fully restore their function. Some non-surgical treatments have shown promise; however, these approaches are generally limited by burst release and poor localization of diverse molecules. In this proof-of-concept study, we developed a nanoparticle (NP) delivery system to efficiently deliver high- and low-solubility drug molecules. Nanoparticles of cellulose acetate and polycaprolactone-polyethylene glycol conjugated with 1-oxo-1H-pyrido [2,1-b][1,3]benzoxazole-3-carboxylic acid (PBC), a novel fluorescent dye, were prepared by the oil-in-water emulsion. Two drugs, a water insoluble indomethacin (IND) and a water soluble 4-aminopyridine (4-AP), were used to study their release patterns. Electron microscopy confirmed the spherical nature and rough surface of nanoparticles. The particle size analysis revealed a hydrodynamic radius ranging ~150–162 nm based on dynamic light scattering. Zeta potential increased with PBC conjugation implying their enhanced stability. IND encapsulation efficiency was almost 3-fold higher than 4-AP, with release lasting up to 4 days, signifying enhanced solubility, while the release of 4-AP continued for up to 7 days. Nanoparticles and their drug formulations did not show any apparent cytotoxicity and were taken up by human IVD nucleus pulposus cells. When injected into coccygeal mouse IVDs in vivo, the nanoparticles remained within the nucleus pulposus cells and the injection site of the nucleus pulposus and annulus fibrosus of the IVD. These fluorescent nano-formulations may serve as a platform technology to deliver therapeutic agents to IVDs and other tissues that require localized drug injections. Full article

Benzoxazole and naphthoxazole fused systems are found in many biologically active molecules. Novel benzoxazole and naphthoxazole analogs functionalized by the 2,4-dihydroxyphenyl moiety were designed, obtained and evaluated as a broad spectrum of biological potency compounds. Sulfinylbis[(2,4-dihydroxyphenyl)methanethione] or its analogs and 2-aminophenols or 1-amino-2-naphthol were used as starting reagents. 4-(Naphtho[1,2-d][1,3]oxazol-2-yl)benzene-1,3-diol was identified as the most promising compound of the nanomolar activity against AChE (IC₅₀ = 58 nM) of the mixed-type inhibition and of the moderate activity against BChE (IC₅₀ = 981 nM). The higher antiproliferative potency against a panel of human cancer cell lines for naphtho[1,2-d][1,3]oxazoles than for benzoxazoles was found. The activity of the analog with chlorine atom was in the range of 2.18–2.89 µM (IC₅₀) against all studied cells and it is similar to that of cisplatin studied comparatively. Moreover, this compound was not toxic at this concentration to human normal breast cells and keratinocytes. For some compounds it also has proved antioxidant properties at the level of IC₅₀ = 0.214 µM, for the most active compound. The lipophilicity of all compounds, expressed as log p values, is within the range recommended for potential drugs. The biological activity profile of the considered analogs and their lipophilic level justify the search for agents used in AD or in anticancer therapy in this group of compounds. Full article

Functionally substituted 1,2-benzisoxazoles are very important and promising heterocycles with various pharmacological activities. Benzoxazoles containing reactive 3-chloromethyl and 5-amino groups are practically unexplored derivatives in this series. In this communication, the simple method for the synthesis of N-[3-(chloromethyl)-1,2-benzisoxazol-5-yl]acetamide which is an interesting precursor for the preparation of a series of 3,5-disubstituted benzoxazoles was described. The structure of the synthesized compound was established by elemental analysis, high-resolution mass spectrometry, ¹H, ¹³C NMR and IR spectroscopy, and mass spectrometry. Full article

Novel catechol thio-ethers with different heterocyclic substituents at sulfur atom were prepared by reacting 3,5-di-tert-butyl-6-methoxymethylcatechol with functionalized thiols under acidic conditions. A common feature of compounds is a methylene bridge between the catechol ring and thioether group. Two catechols with the thio-ether group, bound directly to the catechol ring, were also considered to assess the effect of the methylene linker on the antioxidant properties. The crystal structures of thio-ethers with benzo-thiazole moieties were established by single-crystal X-ray analysis. The radical scavenging and antioxidant activities were determined using 2,2′-diphenyl-1-picrylhydrazyl radical test, ABTS^∙+, CUPRAC (TEAC) assays, the reaction with superoxide radical anion generated by xanthine oxidase (NBT assay), the oxidative damage of the DNA, and the process of lipid peroxidation of rat liver (Wistar) homogenates in vitro. Most catechol-thioethers exhibit the antioxidant effect, which varies from mild to moderate depending on the model system. The dual anti/prooxidant activity characterizes compounds with adamantyl or thio-phenol substituent at the sulfur atom. Catechol thio-ethers containing heterocyclic groups (thiazole, thiazoline, benzo-thiazole, benzo-xazole) can be considered effective antioxidants with cytoprotective properties. These compounds can protect molecules of DNA and lipids from the different radical species. Full article

Liquid organic scintillators are important devices for measurements of neutron radiation. Currently, large-scale liquid organic scintillators have capabilities of detecting neutrons, but the determination of the neutron energy spectra is a challenge. This work aims to measure the responses of two liquid two-component scintillators to mono-energetic neutron radiation and to determine their light output function, which is necessary for proper neutron energy spectra determination. Both scintillators are composed of the solvent di-iso-propyl-naphthalene (DIPN) mixed isomers. The first scintillator, labeled PYR5/DIPN, contains the luminophore 1-phenyl-3-(2,4,6-trimethyl-phenyl)-2-pyrazoline with a concentration of 5 g/L. The second scintillator labeled THIO5/DIPN contains the luminophore 2,5-bis(5-tert-butyl-benzoxazol-2-yl)thiophene also with a concentration of 5 g/L. The responses to neutron energies of 1.5 MeV, 2.5 MeV, and 19 MeV are measured at PTB in Braunschweig. The responses to neutron energies of 2.45 MeV and 14 MeV were measured at CTU in Prague using DD and DT reactions. The responses to a silicon filtered beam were measured at Research Centre Řež. The measurements were processed using a two-parameter spectrometric system NGA-01 to discriminate neutrons from gamma rays. The obtained responses are dominated by recoil protons from elastic collisions of neutrons with hydrogen atoms. The edge of the response of recoil protons gives information about the light output of neutrons, compared to gamma rays for the same radiation energy. The light output function for protons in the PYR5/DIPN scintillator is $L\left(E_{\mathrm{p}}\right)=0.6294E_{\mathrm{p}}-1.00(1-\exp (-0.4933E_{\mathrm{p}}^{0.95}))$. The light output function for protons in the THIO5/DIPN scintillator is $L\left(E_{\mathrm{p}}\right)=0.6323E_{\mathrm{p}}-1.00(1-\exp (-0.4986E_{\mathrm{p}}^{0.9883}))$. The light output functions well resemble the standard shape, and they are quite similar to each other. That suggests a weak influence of the luminophore on the light output function. The light output functions are ready to be incorporated to the response matrix for the neutron energy spectra determination. Full article

Chitosan is a valuable, functional, and biodegradable polysaccharide that can be modified to expand its applications. This work aimed to obtain chitosan derivatives with fluorescent properties. Three heterocyclic aromatic dyes (based on benzimidazole, benzoxazole, and benzothiazole) were synthesized and used for the chemical modification of chitosan. Emission spectroscopy revealed the strong fluorescent properties of the obtained chitosan derivatives even at a low N-substitution degree of the dye. The effect of high-energy ultraviolet radiation (UV–C) on modified chitosan samples was studied in solution with UV–Vis spectroscopy and in the solid state with FTIR spectroscopy. Moreover, cytotoxicity towards three different cell types was evaluated to estimate the possibilities of biomedical applications of such fluorescent chitosan-based materials. It was found that the three new derivatives of chitosan were characterized by good resistance to UV–C, which suggests the possibility of using these materials in medicine and various industrial sectors. Full article

The fluorosulfate derivatives of benzoxazole attract attention since benzoxazole-based compounds have a wide range of biological activities, and the ability of the –SO₂F group to react with various functional groups makes it possible to synthesize various new derivatives. The new 2-(2-(fluorosulfonyloxy)phenyl)benzoxazole (2) has been synthesized by the SuFEx click reaction in a two-chamber reactor. Compound 2 is the first example of a benzoxazole derivative with a fluorosulfate-containing substituent at position two of the benzoxazole heterocycle. The anti-cancer potency of 2 was evaluated in silico using molecular docking. The docking results suggest that title compound 2 is of great interest for further studies as a possible anaplastic lymphoma kinase inhibitor. Full article