https://scholar.dgist.ac.kr/handle/20.500.11750/825 Tue, 27 Oct 2026 07:03:25 GMT 2026-10-27T07:03:25Z https://scholar.dgist.ac.kr/handle/20.500.11750/60983 Title: Competing-ion-promoted U(VI) adsorption in in situ-formed hydrogen-bonded organic frameworks Author(s): Byun, Asong; An, Yejin; Kim, Sohyeon; Pawar, Harshada Khanderao; Moon, Dohyun; Park, Jinkyu; Park, Jinhee Abstract: Hydrogen-bonded organic frameworks (HOFs) offer a versatile platform for efficient capture of U(VI), in which carboxylic acid groups as coordination sites can be densely incorporated and spatially organized within porous architectures. However, U(VI) adsorption is often constrained by the inherent coupling between carboxylic acid deprotonation, which favors uranyl coordination, and framework dissolution in aqueous media. Herein, two isomeric naphthalenediimide-based HOFs (m-HOF and p-HOF) with identical carboxylate densities but distinct inter-carboxylate geometries and pore structures reveal geometry-dependent adsorption behavior: the shorter inter-carboxylate spacing in m-HOF facilitates more efficient U(VI) coordination at low concentrations, whereas the larger pore architecture of p-HOF allows higher uptake at elevated concentrations. Notably, the presence of competing ions such as Gd3+ induces a pronounced salting-out effect that suppresses framework dissolution, leading to markedly enhanced maximum adsorption capacities of 1130 and 1500 mg g- 1 at pH 5 for m-HOF and p-HOF, respectively, without compromising rapid uptake kinetics. The resulting robustness enables efficient U (VI) removal from simulated and natural seawater with facile acid-triggered desorption, highlighting a competing-ion-promoted adsorption strategy for HOF sorbents operating in complex ionic environments. Mon, 31 Aug 2026 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/60983 2026-08-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60483 Title: Metal-dependent adsorption and photothermal-assisted catalysis in heterometallic metal-organic frameworks Author(s): Seo, Eunho; Kim, Dongwook; Park, Jinhee Abstract: The modular nature of metal-organic frameworks (MOFs) enables structural and functional tuning through controlled combinations of organic linkers and metal ions. Here, we report an isostructural MOF series, M-DGIST-20, constructed from trinuclear TiM2(mu 3-O)(COO)6 (M2+ = Ni2+, Co2+, and Mn2+) clusters and a naphthalenediimide-based ligand. The frameworks feature high porosity (approximate to 85% void volume) and serve as a platform to examine composition-function relationships. Iodine adsorption experiments reveal metal-dependent kinetics, with Ni-DGIST-20 showing the fastest uptake due to stronger M-I2 interactions and higher structural robustness. Post-synthetic coordination of imidazole at open metal sites further increases the adsorption rate and capacity. In addition, efficient photothermal conversion and accessible metal sites in M-DGIST-20 allow localized heating and Lewis acidic catalysis, accelerating the Knoevenagel condensation and subsequent Michael addition-intramolecular cyclization. This study demonstrates how compositional and post-synthetic tuning can modulate adsorption and catalytic activity of MOFs. Sat, 28 Feb 2026 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/60483 2026-02-28T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/59328 Title: Cooperative Metal Ion Combinations in Ti-Based Multivariate Metal-Organic Frameworks Author(s): Seo, Eunho; Kim, Mijin; Byun, Asong; Lim, Subin; Moon, Dohyun; Oh, Hyunchul; Park, Jinhee Abstract: Multivariate metal-organic frameworks (MTV-MOFs), which incorporate multiple metal ions or organic linkers within a single framework, provide a powerful platform for investigating structure-composition-property relationships, which in turn enable the rational tuning of material performance. To establish such a correlation, it is critical to achieve precise compositional control while maintaining high crystallinity, thereby minimizing variability in crystallinity and disorder as confounding factors. We report a family of titanium-based multivariate metal-organic frameworks (MTV-MOFs), Ti2M4(mu 3-O)2pbpta3 (designated DGIST-14; M = Ni2+, Co2+, Mn2+), in which various combinations of transition metal ions are integrated into heterometallic clusters within highly crystalline soc-topology frameworks. Based on the hypothesis that Ti4+, a hard acid, can direct the formation of robust frameworks through strong interactions with hard basic carboxylate linkers, we aim to incorporate soft M2+ without compromising structural integrity. This approach facilitates the integration of diverse transition metal ions with precise control over metal ratios. The synergy among the metal centers leads to substantial improvements in structural stability, surface area (up to similar to 4600 m2/g), and gas uptake (up to similar to 1677 cm3/g). Notably, the controlled incorporation of Ni2+ and Mn2+ ions enables the selective generation of singlet oxygen under visible-light via a metal-composition-dependent pathway. This work establishes a structure-composition-function relationship in Ti-based MTV-MOFs and demonstrates a design strategy that leverages cooperative metal-ion combinations to simultaneously optimize framework stability and photoactivity. Fri, 31 Oct 2025 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/59328 2025-10-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/58965 Title: Targeted Selenite Adsorption Using Defective Fe-BTC: Effective in Acidic and Alkaline Conditions Author(s): Byun, Asong; Lee, Byeoksong; Jeong, Yujin; Kang, Joongoo; Park, Jinkyu; Park, Jinhee Abstract: Amorphous Fe-BTC, characterized by entirely defective metal nodes, has been employed for the effective adsorption of toxic selenite anions from aqueous solutions. Remarkably, Fe-BTC maintains high adsorption efficiency across a broad pH range (2-12), achieving a maximum adsorption capacity of 491 mg g-1, ranking among the highest recorded for adsorbents, including MOFs. The adsorption process involves distinct chemical interactions depending on pH: weak and variable interactions under acidic conditions (pH 2) and strong, diverse coordination modes under alkaline conditions (pH 11). Notably, the strong coordination ability of selenite ensures high selectivity over selenate and competing anions such as Cl-, NO2-, NO3-, CO32-, SO42-, and PO43-. The abundance of metal defects endows Fe-BTC with superior adsorption capacity compared to crystalline Fe-MOF, MIL-100(Fe). This study provides a comparative analysis of selenite adsorption on Fe-BTC under acidic and alkaline conditions, emphasizing pH-dependent adsorption mechanisms and their implications for designing effective adsorbents for toxic species removal. Sun, 31 Aug 2025 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/58965 2025-08-31T15:00:00Z