Epitaxial Growth of Hetero-Ln-MOF Hierarchical Single Crystals for Domain- and Orientation-Controlled Multicolor Luminescence 3D Coding Capability

Highly porous organoclay-supported bimetal-organic framework (CoNi-MOF/OC) composite with efficient and selective adsorption of organic dyes

Herein, a highly porous bimetal-organic framework (bi-MOF) based on cobalt and nickel was successfully in situ grown on organoclay (OC) clusters by solvothermal method. Accordingly, the hierarchical porous CoNi-MOF/OC composite with a superior specific surface area of 2046 m²/g and a large pore volume of 0.763 cm³/g was obtained, which facilitated the adsorption of organic dyes. A morphological study using scanning electron microscopy indicated the formation of uniform bi-MOF crystals on the OC plates. Furthermore, the single- and multi-dye adsorption assays were implemented to precisely evaluate the adsorption capacity and selectivity of CoNi-MOF/OC composite to anionic and cationic dyes. The results revealed a high adsorption capacity of 58.61 mg/g at an adsorbent content of 15 mg, initial dye concentration of 20 ppm, and contact time of 25 min for MB, which is superior to several existing clay-based adsorbents. The adsorption kinetics study showed that the adsorption of cationic and anionic dyes onto the CoNi-MOF/OC composite followed the pseudo-second-order kinetic model. Interestingly, the regeneration study showed appropriate reusability and stability of the CoNi-MOF/OC composite for the removal of organic dyes with an almost unchanged structure after four regeneration cycles. The results of this study provide new insights for the rational design and fabrication of next-generation clay-based adsorbent by combining the synergistic advantages of bi-MOF with superior specific surface area and pore volume with organoclay composition and structure.

Upconversion Luminescence through Cooperative and Energy-Transfer Mechanisms in Yb3+ -Metal-Organic Frameworks

Lanthanide-doped metal-organic frameworks (Ln-MOFs) have versatile luminescence properties, however it is challenging to achieve lanthanide-based upconversion luminescence in these materials. Here, 1,3,5-benzenetricarboxylic acid (BTC) and trivalent Yb³⁺ ions were used to generate crystalline Yb-BTC MOF 1D-microrods with upconversion luminescence under near infrared excitation via cooperative luminescence. Subsequently, the Yb-BTC MOFs were doped with a variety of different lanthanides to evaluate the potential for Yb³⁺ -based upconversion and energy transfer. Yb-BTC MOFs doped with Er³⁺ , Ho³⁺ , Tb³⁺ , and Eu³⁺ ions exhibit both the cooperative luminescence from Yb³⁺ and the characteristic emission bands of these ions under 980 nm irradiation. In contrast, only the 497 nm upconversion emission band from Yb³⁺ is observed in the MOFs doped with Tm³⁺ , Pr³⁺ , Sm³⁺ , and Dy³⁺ . The effects of different dopants on the efficiency of cooperative luminescence were established and will provide guidance for the exploitation of Ln-MOFs exhibiting upconversion.

Highly Efficient Multiphoton Absorption of Zn-AIEgen Frameworks

A series of luminescent frameworks were synthesized from the selective combination of AIE-linker tetra-(4-carboxylphenyl)ethylene (H 4 TCPE) and Zn 2+ . Complex 1 was formed by the close packing of Zn-TCPE hinge, and isostructural complexes 2 - 5 were constructed by the linkage of Zn-TCPE layer and pillar ligand. These complexes exhibit highly efficient multiphoton excited photoluminescence (MEPL) concomitant third-harmonic generation (THG). Interestingly, multiphoton apparent parameters of 1 are far superior to some excellent multiphoton emission materials, even the perovskite nanocrystal. The incorporation of pillar linkers slows down the charge transfer between layers of Zn-TCPE, and the aromatic core of pillar linkers has a great influence on the MEA performance of corresponding frameworks. The unprecedented structural and optical tuning of high performance MPA crystalline materials provides efficient suggestion for the design of next generation multiphoton absorption materials.

Laterally Engineering Lanthanide-MOFs Epitaxial Heterostructures for Spatially Resolved Planar 2D Photonic Barcoding

Metal-organic frameworks (MOFs) heterostructures with domain-controlled emissive colors have shown great potential for achieving high-throughput sensing, anti-counterfeit and information security. Here, a strategy based on steric-hindrance effect is proposed to construct lateral lanthanide-MOFs (Ln-MOFs) epitaxial heterostructures, where the channel-directed guest molecules are introduced to rebalance in-plane and out-of-plane growth rates of the Ln-MOFs microrods and eventually generate lateral MOF epitaxial heterostructures with controllable aspect ratios. A library of lateral Ln-MOFs heterostructures are acquired through a stepwise epitaxial growth procedure, from which rational modulation of each domain with specific lanthanide doping species allows for definition of photonic barcodes in a two-dimensional (2D) domain with remarkably enlarged encoding capacity. The results provide molecular-level insight into the use of modulators in governing crystallite morphology for spatially assembling multifunctional heterostructures.

Structural Diversity of Zinc(II), Manganese(II), and Gadolinium(III) Coordination Polymers Based on Two Isomeric N-Heteroaromatic Polycarboxylate Ligands: Structures and Their Derived Mn2O3 for Lithium Storage Applications

Tuning the coordination sites of two isomeric semirigid ligands, 5-(4-pyridin-3-yl-benzoylamino)isophthalic acid (3-H₂PBI) and 5-(4-pyridin-4-yl-benzoylamino)isophthalic acid (4-H₂PBI), afforded six new coordination polymers (CPs), [Zn(3-PBI)(H₂O)]_n (1), {[Mn₂(3-PBI)₂(H₂O)]·DMF·2H₂O}_n (2), {[Gd₂(3-PBI)₃(H₂O)₃]·DMF·3H₂O}_n (3), {[Zn₂(4-PBI)₂]·H₂O}_n (4), {[Mn₂(4-PBI)₂(H₂O)₂]·4H₂O}_n (5), and {(Me₂NH₂)[Gd(4-PBI)₂]·H₂O}_n (6). Structural analysis shows that 1 consists of 2D honeycomb (6,3) net, three sets of networks interlace mutually, generating an unexpected 2D + 2D + 2D → 3D polycatenating interesting system. 2 exhibits a 3D pcu topology. 3 presents a unique 3D with 3,3,6T13 network topology. 4 possesses 3D 2-fold interpenetrated structure with rutile topology. 5 presents an alluring 2D architecture comprising two distinct topologies (kgd and hcb), stacked arrangement in an unexpected ABBABB mode. 6 displays 2D (4,4)-grid network. A differentiation of these structural features indicate that coordination connectivity of metals, together with binding modes of two ligands are accountable for the fascinating structural contrast. In addition, 2 and 5 were then transformed into Mn₂O₃ via a simple heat treatment. Electrochemical test results show that both of the obtained Mn₂O₃ moieties exhibit stable lithium storage properties and excellent rate capabilities.

Pressure-Induced Multiphoton Excited Fluorochromic Metal-Organic Frameworks for Improving MPEF Properties

In multiphoton excited fluorescence (MPEF), high-energy upconversion emission is obtained from low-energy excitation by absorbance of two or more photons simultaneously. In a pressure-induced fluorochromic process, the emission energy is switched by outer pressure stimuli. Now, five metal-organic frameworks containing the same ligand with simultaneous multiphoton absorption and pressure-induced fluorochromic attributes were studied. One-, two-, and three-photon excited fluorescence (1/2/3PEF) can be achieved in the frameworks, which exhibit pressure-induced blue-to-yellow fluorochromism. The performances are closely dependent with the topologies, flexibilities, and packing states of the frameworks and chromophores therein. The multiphoton upconversion performance can be intensified by pressure-related structural contraction. Over ten-fold increment in the 2PA active cross-section up to 2217 GM is achieved in pressed LIFM-114 compared with the 210 GM for pristine sample at 780 nm.

Spherical Sandwich Au@Pd@UIO-67/Pt@UIO- n ( n = 66, 67, 69) Core-Shell Catalysts: Zr-Based Metal-Organic Frameworks for Effectively Regulating the Reverse Water-Gas Shift Reaction

In this study, spherical sandwich Au@Pd@UIO-67/Pt@UIO- n ( n = 66, 67, 69) core-shell catalysts were assembled. Au nanoparticles (NPs) were used as the core for the epitaxial growth of Pd shells, and Au@Pd core-shell NPs were successfully encapsulated in the center of monodispersed Au@Pd@UIO-67 nanospheres. Pt NPs were fully fixed onto the nanosphere surfaces to obtain Au@Pd@UIO-67/Pt composites; further coating with UIO- n led to Au@Pd@UIO-67/Pt@UIO- n, in which Pt NPs are sandwiched between the Au@Pd@UIO-67 core and the UIO- n shell. The Au@Pd core-shell NPs efficiently controlled the morphology and structure of UIO-67 and enhanced the CO selectivity of the catalyst. Pt NPs increased the CO₂ conversion, and the UIO- n component effectively regulated the reverse water-gas shift reaction.

Antimonene: From Experimental Preparation to Practical Application

The two-dimensional material antimonene was first reported in 2015. Subsequently, its unique properties, including enhanced stability, high carrier mobility, and band-gap tunability, were predicted theoretically. These theoretical results have motivated experimental confirmation and thus a better understanding of this new material. Recently, the preparation of antimonene and its attempted use in several applications have attracted extensive attention. This Minireview focuses on both the experimental preparation and practical applications of antimonene, including the results of recent research on novel methods of preparing antimonene and its potential applications in optoelectronic devices, electrocatalysis, energy storage, and cancer therapy. Moreover, it provides insight that could further improve the preparation of antimonene and also describes numerous opportunities for application.

ESIPT-Modulated Emission of Lanthanide Complexes: Different Energy-Transfer Pathways and Multiple Responses

Two series of isostructural lanthanide coordination complexes, namely, LIFM-42(Ln) (Ln=Eu, Tb, Gd, in which LIFM stands for the Lehn Institute of Functional Materials) and LIFM-43(Ln) (Ln=Er, Yb), were synthesized through the self-assembly of an excited-state intramolecular proton transfer (ESIPT) ligand, 5-[2-(5-fluoro-2-hydroxyphenyl)-4,5-bis(4-fluorophenyl)-1H-imidazol-1-yl]isophthalic acid (H₂ hpi2cf), with different lanthanide ions. In the coordination structures linked by the ligands and oxo-bridged Ln^III ₂ clusters (for LIFM-42(Ln) series) or isolated Ln^III ions (for LIFM-43(Ln) series), the ESIPT ligand can serve as both the host and antenna for protecting and sensitizing the photoluminescence (PL) of Ln^III ions. Meanwhile, the -OH⋅⋅⋅N active sites on the ligands are vacant, which provides availability to systematically explore the PL behavior of Ln complexes with ESIPT interference. Based on the accepting levels of different lanthanide ions, energy transfer can occur from the T₁ (K*) or T₁ (E*) (K*=excited keto form, E*=excited enol form) excited states of the ligand. Furthermore, the sensitized lanthanide luminescence in both visible and near-infrared regions, as well as the remaining K* emission of the ligand, can be modulated by the ESIPT responsiveness to different solvents, anions, and temperature.