Hyosun Lee

In this study, 2‐(piperidin‐1‐ylmethyl)quinoline (L_A) and 1‐(naphthalen‐2‐ylmethyl)piperidine (L_B) ligands were utilized alongside palladium(II) acetate [Pd(OAc)₂] and N,N‐Dimethylanilinium tetrakis (pentafluorophenyl)borate as a cocatalyst for the in situ addition polymerization of norbornene (NB). The ligand L_B system demonstrated superior catalytic performance compared with that of the ligand L_A system, achieving 99% versus 94% conversion for NB to polynorbornene (PNB) at 25°C in chlorobenzene. To validate the catalytic activities of these in situ catalytic systems, Pd (II) complexes, [L_APd(OAc)₂] and [L_BPd(μ‐OAc)]₂, were synthesized and characterized. X‐ray structure analysis revealed that [L_APd(OAc)₂] adopted a square planar geometry, whereas [L_BPd(μ‐OAc)]₂ exhibited a distinctive clamshell structure. These complexes were also employed for the vinyl addition polymerization of NB under the same conditions as in situ catalytic systems. The active real Pd(II) complexes demonstrated slightly lower conversions compared with those of the in situ catalytic systems, achieving over 90% conversions for both [L_APd(OAc)₂] and [L_BPd(μ‐OAc)]₂. Furthermore, both catalytic systems were subsequently used for the (co)polymerization of NB and its derivatives, such as 5‐butylbicyclo[2.2.1]hept‐2‐ene (Bu‐NB), methyl bicyclo[2.2.1]hept‐5‐ene‐2‐carboxylate (Me‐NB), and bicyclo[2.2.1]hept‐5‐en‐2‐ylmethyl acetate (AAc‐NB), yielding relatively lower conversions.

Precise control over molecular dispersity and supramolecular assembly is essential for designing nanostructures with targeted properties and functionalities. In this study, we explore the impact of molecular dispersity in BTA-oligo(AA)₃ oligomers on the formation and structural organization of Au nanomaterials in an aqueous system. Discrete and polydisperse BTA-oligo(AA)₃ samples are systematically synthesized and characterized to evaluate their role as templates for nanostructure formation. UV-vis spectroscopy and TEM analyses reveal distinct differences in the resulting nanostructures. Specifically, discrete oligomers facilitate the formation of well-defined, interconnected Au nanonetworks with high structural uniformity, even at elevated concentrations. In contrast, polydisperse oligomers facilitated the formation of isolated Au nanoparticles with limited control over morphology and connectivity. These differences are attributed to the greater molecular uniformity and enhanced self-assembly capabilities of the discrete oligomers, which serve as effective templates for directing Au precursor organization and reduction into ordered nanostructures. This study provides mechanistic insight into how molecular dispersity affects the templating and assembly of gold nanomaterials. The findings offer a promising strategy for developing tailored nanostructures with interconnected morphologies and controlled optical and structural properties, paving the way for advanced applications.

Herein, Cu(II), Zn(II), and Cd(II) complexes with furan‐derived Schiff base ligand, (E)‐N¹,N¹‐diethyl‐N²‐(furan‐2‐ylmethylene)ethane‐1,2‐diamine(DEF), were synthesized. The synthesized ligand and M(II) (M = Cu, Zn, and Cd) complexes were characterized to confirm their purity and successful synthesis using ¹H NMR, ¹³C NMR, and FTIR spectroscopy. Thermal analysis demonstrated their stability, whereas UV‐Vis spectroscopy and molar conductance studies provided insights into their electronic properties and coordination behavior. Additionally, X‐ray diffraction studies indicated that the Zn(II) and Cd(II) complexes have distorted tetrahedral geometries, whereas the Cu(II) complex adopted distorted square planar geometry. The studied complexes showed remarkable free‐radical scavenging activity. Furthermore, they exhibited good inhibitory activity against urease and α‐amylose. In particular, [Cu(DEF)Cl₂] showed the best antioxidant activity, with an IC₅₀ of 3.21 ± 0.19 μM, and the highest α‐amylose inhibitory activities, with an IC₅₀ of 6.11 ± 0.33 μM. Moreover, [Cd(DEF)Br₂] proved to be more potent against Jack bean and Bacillus pasteurii ureases, with IC₅₀ values of 3.90 ± 0.11 μM and 6.01 ± 0.10 μM, respectively. Molecular docking studies showed a good correlation between the biological activities of the synthesized [M(DEF)X₂] complexes. Thus, the proposed compounds can serve as promising candidates for the treatment of infectious diseases.

A thiophene-derived Schiff base ligand (E)-2-morpholino-N-(thiophen-2-ylmethylene)ethanamine was used for the synthesis of M(II) complexes, [TEM(M)X₂] (M = Co, Cu, Zn; X = Cl; M = Cd, X = Br). Structural characterization of the synthesized complexes revealed distorted tetrahedral geometry around the M(II) center. In vitro investigation of the synthesized ligand and its M(II) complexes showed considerable anti-urease and leishmanicidal potential. The synthesized complexes also exhibited a significant inhibitory effect on urease, with IC₅₀ values in the range of 3.50–8.05 μM. In addition, the docking results were consistent with the experimental results. A preliminary study of human colorectal cancer (HCT), hepatic cancer (HepG2), and breast cancer (MCF-7) cell lines showed marked anticancer activities of these complexes.

Cobalt(II) and copper(II) complexes supported by 4‐(quinolin‐2‐ylmethyl)morpholine (L) were characterized, and their reactivity toward the ring‐opening polymerization (ROP) of rac‐lactide (rac‐LA) was studied. The use of [LMCl₂]/LiOⁱPr and [LMCl₂]/LiMe (M = Co, Cu) resulted in over 95% conversion within 10 min at 25 °C. The effect of the initiating group and geometry of the metal complexes steered the heterotactic enchainment of the resultant polylactide(PLA). The Co(II)/LiMe system represents the first example of the ROP of rac‐LA with high heterotactic enchainment (P_r = 0.92) with 98% conversion at 0 °C.

Control of polymer topologies is essential to determine their unique physical properties and potential applications. The polymer topologies can have a critical effect on pigment dispersion owing to their unique architectures; however, studies using polymer topologies on pigment dispersion in aqueous systems are scarce. Thus, this study proposes various topologies of polyether-based waterborne synergists, such as linear, hyperbranched, and branched cyclic structures. Specifically, we applied branched types of polyglycidols (PGs) as a synergist to provide polymer topology-dependent dispersibility for the surface-modification of Red 170 particles through adsorption and steric hindrance. The topology-controlled PG synergists (PGSs) were successfully prepared by post-polymerization modification with phthalimide and benzoyl groups. Particularly, the branched types of PGSs, branched cyclic PGS (bc-PGS), and hyperbranched PGS (hb-PGS) exhibited improved dispersibility through adsorption on top of the pigment, interaction between dispersant (BYK 190) and pigment, and steric effect. Surprisingly, hb-PGS conferred the Red 170 pigment particles with superior storage stability than that of bc-PGS despite their similar structural features. This study suggests the widespread potential application of PGSs as waterborne synergists for various dispersion applications.

Cu1–4, comprising novel Cu complexes based on quinoline or pyridine and morpholine or piperidine, interact with DNA, leading to the destabilization of DNA duplex and causing oxidative DNA cleavage via the superoxide dismutase (SOD) pathway.