Chemistry - An Asian Journal最新文献

In article number e202400427, Apurba Lal Koner and co-workers develop a cutting-edge method for selectively monitoring tyrosinase activity in real-time using the small-molecule fluorescent probe. This impressive red-emissive probe glows when it interacts with tyrosinase, providing dynamic insights into its enzymatic function with potential clinical implications.

Given the rapid growth of the nuclear sector, effective treatment of radioactive iodine is critical. Herein, we report the synthesis and the iodine adsorption properties of croconic acid (CTPB) and squaric acid (STPB) containing π-conjugated novel zwitterionic conjugated porous polymers (CPPs). The CPPs have been synthesized through a condensation reaction of tris(4-aminophenyl)benzene with croconic acid or squaric acid in high yields (~95%). The ionic nature of the polymers promoted high iodine/polyiodide vapour adsorption capacity of up to 4.6 g/g for CTPB and 3.5 g/g for STPB under ambient pressure at 80 °C. The zwitterionic framework (croconic acid or squaric acid units) coupled with the aromatic units is expected to effectively capture molecular iodine (I2) and polyiodides (I3- and I5-). The iodine adsorption properties of the polymers have been studied using Fourier-Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Brauner-Emmett-Teller (BET) analysis, and Raman Spectroscopy. Besides this work, there are only three ionic units for effective iodine adsorption. This work demonstrates the importance of zwitterionic units in the porous network reported for iodine adsorption and separation.

The icosahedral Au135+ core is a recurrent building block in ligand-protected gold clusters involving an 8-cluster electron 1S21P6 electronic shell. Such a prototypical structure enables a spherical aromatic behavior as given by long-range magnetic shielding. Recently, the Au20(tBu3P)8 cluster featuring a contrasting cuboctahedral core with formally neutral gold atoms appears as a novel core architecture with the potential to be considered as another potential building block towards functional nanostructures. Here, we explore the ligand-core interaction and spherical aromatic characteristics of Au20(tBu3P)8, in order to provide a direct connection to classical icosahedral spherical aromatic compounds, now involving a cuboctahedral core structure. Such characteristics suggest rationalization of their robustness in terms of certain electron counts, enabling a shielding cone property in ligand-protected metallic clusters, which favors bridging organic and inorganic planar/spherical aromatic species towards the unification of the aromaticity concept and designing guidelines for further achievements.

A series of rare earth alkoxides bearing amine-bridged bis(phenolato) ligands were synthesized through sequential reactions of RE(C5H5)3(THF) (RE = Y, Lu) or Nd[N(SiMe3)2]3 with bis(phenols) LH2 and CF3CH2OH. Complexes REL(OCH2CF3)(THF)n (1-6) bearing different aryl-substituents were obtained in good yields of 59-70%. They were applied in the ring-opening polymerization (ROP) of rac-β-butyrolactone (rac-BBL), which showed good activity (TOF up to 27,300 h-1), resulting in syndiotactically enriched poly(3-hydroxybutyrate) (PHB) (Pr up to 0.86) with narrow polydispersities (PDI ≤ 1.27). The yttrium complex 3 bearing bulky o-1,1-diphenylethyl substituents outperformed other complexes, suggesting that the smaller ionic radii of metal centers and bulky ortho substituents of ancillary ligands play crucial roles in controlling the activity and stereoselectivity in ROP of rac-BBL. Kinetics of the polymerization of rac-BBL initiated by complex 3 was investigated, which revealed first order dependences on the monomer and initiator concentrations, respectively.

The Zika virus (ZIKV) is a global health threat due to its rapid spread and severe health implications, including congenital abnormalities and neurological complications. Differentiating ZIKV from other arboviruses such as dengue virus (DENV) is crucial for effective diagnosis and treatment. This study presents the development of a biosensor for detecting the ZIKV non-structural protein 1 (NS1) using gold nanoparticles (AuNPs) functionalized with monoclonal antibodies employing dynamic light scattering (DLS). The biosensor named ZINS1-mAb-AuNP exhibited specific binding to the ZIKV NS1 protein, demonstrating high colloidal stability indicated by a hydrodynamic diameter (DH) of 140 nm, detectable via DLS. In the absence of the protein, the high ionic strength medium caused particle aggregation. This detection method showed good sensitivity and specificity, with a limit of detection (LOD) of 0.96 µg mL-1, and avoided cross-reactivity with DENV2 NS1 and SARS-CoV-2 spike proteins. The ZINS1-mAb-AuNP biosensor represents a promising tool for the early and accurate detection of ZIKV, facilitating diagnostic and treatment capabilities for arboviral infections.

Small molecule-responsive tags for targeted protein degradation are valuable tools for fundamental research and drug target validation. Here, we show that genetically incorporated unnatural amino acids bearing a strained alkene or alkyne functionality can act as a minimalist tag for targeted protein degradation. Specifically, we observed the degradation of strained alkene- or alkyne-containing kinases and E2 ubiquitin-conjugating enzymes upon treatment with hydrophobic tetrazine conjugates. The extent of the induced protein degradation depends on the identity of the target protein, unnatural amino acid, and tetrazine conjugate, as well as the site of the unnatural amino acid in the target protein. Mechanistic studies revealed proteins undergo proteasomal degradation after tetrazine tethering, and the identity of tetrazine conjugates influences the dependence of ubiquitination on protein degradation. This work provides an alternative approach for targeted protein degradation and mechanistic insight, facilitating the future development of more effective targeted protein degradation strategies.

The interplay of ESIPT+TICT mechanisms in 1,8-naphthalimide-hydroxyquinoline (NQ-OH) molecular rotor were reported for the near-IR 'turn-on' emission (λmax 600 nm) and ratiometric (A405nm/A345nm) absorbance-based detection of Al3+ ions in aqueous medium and live cells which were supported by NMR, IR and CV techniques. The limit of detection (LOD) for Al3+ ions is 100 nM and 14.57 nM. The self-assembled spherical aggregates of NQ-OH transformed into cuboidal aggregates upon coordination with Al3+ ions supported by microscopic and dynamic light scattering (DLS) techniques. The complex NQ-OH+Al3+ was further used for the secondary detection of F- ions in aqueous medium via displacement approach with LOD as low as 2.67 nM. A deeper study revealed that the NQ-OH is a solvatochromic dye. Probably, the NQ-OH either in the aggregated state or in the coordination state with Al3+ ions, showed an increase in the emission intensity at 600 nm due to inhibition of the ESIPT process and trigger of the TICT process. We have demonstrated the utility of NQ-OH for the detection of Al3+ ions and NQ-OH+Al3+ complex for the detection of F- ions in MCF7 live cells. We have also discussed the molecular docking studies of NQ-OH with acetylcholinesterase enzyme.

Panchromatic dyes have been highly useful in the realm of optical devices. Here, we report that panchromatic dyes with heterohelicenes have been successfully synthesized using a donor-acceptor strategy. Our synthesis resulted in the creation of π-extended aza[5]helicene oligomers with butadiyne linkages, which displayed bathochromically shifted absorption and emission spectra. The solvent-dependent optical measurements revealed the intramolecular charge transfer characteristic of these molecules, and theoretical calculations described the biased molecular orbitals on the azahelicene units that generated the charge-transfer characteristic. Encouraged by these results, we also prepared donor-acceptor-donor dyads using azahelicenes and dimide derivatives, resulting in panchromatic absorbing characteristics covering the range from 250 nm to 800 nm. Theoretical calculations showed the presence of mixed charge-transfer transitions and localized transitions on the azahelicene units, which led to a broad light-absorbing property covering the near IR region. Additionally, we conducted measurements of circular dichroism and circularly polarized luminescence for the obtained products. The g-values were reduced by oligomerization, indicating that the lowest energy transitions were allowed in nature.

The field of electrogenerated chemiluminescence (ECL) biosensing has witnessed remarkable growth, emphasizing the need for precise detection of biomarkers. The synthesis approach of peptide-based signal probe with high recognition ability and high ECL efficiency is a significant issue in the ECL biosensing. Here, a heavily labeled signal probe was synthesized for ECL peptide-based biosensing tactic by using a new aldehyde bearing cyclometalated Ir(III) complex ([Ir(bt)2(bpy-CHO)PF6 (bt =2-phenylbenzothiazole, bpy-CHO=4'-methyl-[2,2'-bipyridine]-4-carbaldehyde, denoted as Ir1) as ECL signal reagent and streptavidin (SA) as carrier protein. One ECL peptide-based biosensing method was exemplified for the detection of matrix metalloproteinase 2 (MMP-2) by using Ir1 labeled SA (SA-Ir1) as heavily labeled signal probe and biotinylated peptide as molecular recognition substrate. MMP-2 was sensitively detected in the range from 5 to 100 ng/mL with a detection limit of 1.5 ng/mL. Importantly, two detection modes differing in the order of cleavage recognition by MMP-2 and signal transduction with SA-Ir1 were compared for the first time. First cleavage and second signal transduction were proposed to be beneficial to sensitive detection of target, which provides some ideas for biomarker diagnostics in disease screening at an early stage.

Organofluorine compounds have consistently demonstrated practical applications in the life sciences due to the fascinating properties imparted by the fluorine substituents. In recent years, significant advancements have been made in the synthesis of N-fluoroalkyl carbonyl and sulfonyl compounds. This review offers a current overview of the various synthetic routes for N-fluoroalkyl amides/sulfonamides and their transformation to new unexplored N-fluoroalkyl carbonyl/sulfonyl derivatives, categorized into three parts based on the different fluoroalkyl groups.