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Although diamine-appended metal-organic framework (MOF) adsorbents exhibit excellent CO 2 adsorption performance, a continuous decrease in long-term capacity during repeated wet cycles remains a formidable challenge for practical applications. Herein, we present the fabrication of diamine-appended Mg 2 (dobpdc)-alumina beads ( een-MOF/Al - Si - C x ; een = N -ethylethylenediamine; x = number of carbon atoms attached to epoxide) coated with hydrophobic silanes and alkyl epoxides. The reaction of epoxides with diamines in the portal of the pore afforded sufficient hydrophobicity, hindered the penetration of water vapor into the pores, and rendered the modified diamines less volatile. een-MOF/Al-Si-C17-200 ( een-MOF/Al-Si-C17- y ; y = 50, 100, and 200, denoting wt % of C17 with respect to the bead, respectively), with substantial hydrophobicity, showed a significant uptake of 2.82 mmol g -1 at 40 °C and 15% CO 2 , relevant to flue gas concentration, and a reduced water adsorption. The modified beads maintained a high CO 2 capacity for over 100 temperature-swing adsorption cycles in the presence of 5% H 2 O and retained CO 2 separation performance in breakthrough tests under humid conditions. This result demonstrates that the epoxide coating provides a facile and effective method for developing promising adsorbents with high CO 2 adsorption capacity and long-term durability, which is a required property for postcombustion applications.

Porous organic polymers (POPs) are prepared by crosslinked polymerization of multidimensional rigid aromatic building blocks. Generally, POPs can be classified into crystalline covalent organic frameworks (COFs) and other poorly crystalline or amorphous porous polymers. Due to their remarkable intrinsic properties, such as high porosity, stability, tunability, and presence of numerous building blocks, several new POPs are being developed for application across various scientific fields. The essential sensitive functional groups needed for specific applications are not sustained under harsh POP preparation conditions. The recently developed post-synthetic modification (PSM) strategies for POPs have enabled their advanced applications that are otherwise restricted. Owing to the advanced PSM strategies POPs have experienced a blossoming resurgence with diverse functions, particularly in biomedical applications, such as bioimaging tools, drugs, enzymes, gene or protein delivery systems, phototherapy, and cancer therapy. This tutorial review focuses on the recently developed PSM strategies for POPs, especially for biomedical applications, and their future perspectives as promising bioapplicable materials.

Postsynthetic modifications (PSMs) of metal–organic frameworks (MOFs) play a crucial role in enhancing material performance through open metal site (OMS) functionalization or ligand exchange. However, a significant challenge persists in preserving open metal sites during ligand exchange, as these sites are inherently bound by incoming ligands. In this study, for the first time, we introduced alkoxides by exchanging bridging chloride in Ni2Cl2BTDD (BTDD=bis (1H‐1,2,3,–triazolo [4,5‐b],–[4′,5′‐i]) dibenzo[1,4]dioxin) through PSM. Rietveld refinement of synchrotron X‐ray diffraction data indicated that the alkoxide oxygen atom bridges Ni(II) centers while the OMSs of the MOF are preserved. Due to the synergy of the existing OMS and introduced functional group, the alkoxide‐exchanged MOFs showed CO2 uptakes superior to the pristine MOF. Remarkably, the tert‐butoxide‐substituted Ni_T exhibited a nearly threefold and twofold increase in CO2 uptake compared to Ni2Cl2BTDD at 0.15 and 1 bar, respectively, as well as high water stability relative to the other exchanged frameworks. Furthermore, the Grand Canonical Monte Carlo simulations for Ni_T suggested that CO2 interacts with the OMS and the surrounding methyl groups of tert‐butoxide groups, which is responsible for the enhanced CO2 capacity. This work provides a facile and unique synthetic strategy for realizing a desirable OMS‐incorporating MOF platform through bridging ligand exchange. [ABSTRACT FROM AUTHOR]

Although ethylene (C2H4) is one of the most critical chemicals used as a feedstock in artificial plastic chemistry fields, it is challenging to obtain high‐purity C2H4 gas without any trace ethane (C2H6) by the oil cracking process. Adsorptive separation using C2H6‐selective adsorbents is beneficial because it directly produces high‐purity C2H4 in a single step. Herein, Ni(IN)2 (HIN = isonicotinic acid) is computationally discovered as a promising adsorbent with the assistance of the multiscale high‐throughput computational screening workflow and Computation‐Ready, Experimental (CoRE) metal–organic framework (MOF) 2019 database. Ni(IN)2 is subsequently synthesized and tested to show the ideal adsorbed solution theory (IAST) selectivity of 2.45 at 1 bar for a C2H6/C2H4 mixture (1:15), which is one of the top‐performing selectivity values reported for C2H6‐selective MOFs as well as excellent recyclability, suggesting that this material is a promising C2H6‐selective adsorbent. Process‐level simulation results based on experimental isotherms demonstrate that the material is one of the top materials reported to date for ethane/ethylene separation under the conditions considered in this work. [ABSTRACT FROM AUTHOR]

Although CO2 insertion is a predominant phenomenon in diamine‐functionalized Mg2(dobpdc) (dobpdc4−=4,4‐dioxidobiphenyl‐3,3′‐dicarboxylate) adsorbents, a high‐performance metal‐organic framework for capturing CO2, the fundamental function of the diamine carbon chain length in the mechanism remains unclear. Here, Mg2(dobpdc) systems with open metal sites grafted by primary diamines NH2−(CH2)n−NH2 were developed, with en (n=2), pn (n=3), bn (n=4), pen (n=5), hn (n=6), and on (n=8). Based on CO2 adsorption and IR results, CO2 insertion is involved in frameworks with n=2 and 3 but not in systems with n≥5. According to NMR data, bn‐appended Mg2(dobpdc) exhibited three different chemical environments of carbamate units, attributed to different relative conformations of carbon chains upon CO2 insertion, as validated by first‐principles density functional theory (DFT) calculations. For 1‐hn and 1‐on, DFT calculations indicated that diamine inter‐coordinated open metal sites in adjacent chains bridged by carboxylates and phenoxides of dobpdc4−. Computed CO2 binding enthalpies for CO2 insertion (−27.8 kJ mol−1 for 1‐hn and −20.2 kJ mol−1 for 1‐on) were comparable to those for CO2 physisorption (−19.3 kJ mol−1 for 1‐hn and −20.8 kJ mol−1 for 1‐on). This suggests that CO2 insertion is likely to compete with CO2 physisorption on diamines of the framework when n≥5. [ABSTRACT FROM AUTHOR]

MOF-74-type frameworks are considered one of the most promising metal–organic frameworks owing to their remarkable structural features and properties such as a high density of open metal sites, hexagonal channels along the c-axis, and high porosity. Diverse strategies have been adopted to prepare bimetallic MOF-74 frameworks, in the pursuit of synergistic effects and enhanced properties originating from different metal sites that serve as Lewis acidic sites. Moreover, extended versions of the MOF-74-type structure have been demonstrated in terms of ligand extension, featuring enhanced pore size and surface area. The extended variants of MOF-74 are beneficial for the incorporation of additional functional groups due to the relatively larger pore size. Pre- or post-synthetic modification approaches have been applied to introduce functionalities into the framework, resulting in desirable and superior properties such as chemical stability, binding affinity, and catalytic activity. This review addresses the significant progress made in the development of MOF-74-type frameworks with respect to synthetic strategies and modification approaches. [ABSTRACT FROM AUTHOR]

NH3, essential for producing artificial fertilizers and several military and commercial products, is being produced at a large scale to satisfy increasing demands. The inevitable leakage of NH3 during its utilization, even in trace concentrations, poses significant environmental and health risks because of its highly toxic and reactive nature. Although numerous techniques have been developed for the removal of atmospheric NH3, conventional NH3 abatement systems possess the disadvantages of high maintenance cost, low selectivity, and emission of secondary wastes. In this context, highly tunable porous materials such as metal–organic frameworks, covalent organic frameworks, hydrogen organic frameworks, porous organic polymers, and their composite materials have emerged as next‐generation NH3 adsorbents. Herein, recent progress in the development of porous NH3 adsorbents is summarized; furthermore, factors affecting NH3 capture are analyzed to provide a reasonable strategy for the design and synthesis of promising materials for NH3 abatement. [ABSTRACT FROM AUTHOR]

Although numerous porous adsorbents have been investigated for NH3 capture applications, these materials often exhibit insufficient NH3 uptake, low NH3 affinity at the ppm level, and poor chemical stability against wet NH3 conditions. The NH3 capture properties of M2(dobpdc) complexes (M=Mg2+, Mn2+, Co2+, Ni2+, and Zn2+; dobpdc4−=4,4‐dioxidobiphenyl‐3,3‐dicarboxylate) that contain open metal sites is presented. The NH3 uptake of Mg2(dobpdc) at 298 K was 23.9 mmol g−1 at 1 bar and 8.25 mmol g−1 at 570 ppm, which are record high capacities at both pressures among existing porous adsorbents. The structural stability of Mg2(dobpdc) upon exposure to wet NH3 was superior to that of the other M2(dobpdc) and the frameworks tested. Overall, these results demonstrate that Mg2(dobpdc) is a recyclable compound that exhibits significant NH3 affinity and capacity, making it a promising candidate for real‐world NH3‐capture applications. [ABSTRACT FROM AUTHOR]

We synthesized a three-dimensional Mn-based framework [Mn3L2(H2O)3]·7.5DEF·3H2O (1; H3L = tris((4-carboxyl)phenyl)amine, DEF = N,N-diethylformamide) via the solvothermal reaction of Mn2+ and H3L in a mixed DEF/H2O solvent. In the crystal structure of 1, two types of 4- and 8-membered ring channels in the lattice emerge. Three Mn centers in the asymmetric unit adopted distorted octahedral (Mn2 and Mn3) and trigonal bipyramidal (Mn1) arrangements. The photoluminescence of 1 was completely quenched by nitroaromatic compounds and Cu2+ ions. Magnetic properties were studied as a function of temperature and magnetic field, and the results indicated the existence of overall antiferromagnetic couplings between the Mn(II) spins. Weak ferromagnetism was observed at low temperatures due to the possible spin canting in this Mn(II) system. [ABSTRACT FROM AUTHOR]

Two new heterometallic metal–organic frameworks (MOFs), LnZnTPO 1 and 2, and two homometallic MOFs, LnTPO 3 and 4 (Ln=Eu for 1 and 3, and Tb for 2 and 4; H3TPO=tris(4‐carboxyphenyl)phosphine oxide) were synthesized, and their structures and properties were analyzed. They were prepared by solvothermal reaction of the C3‐symmetric ligand H3TPO with the corresponding metal ion(s) (a mixture of Ln3+ and Zn2+ for 1 and 2, and Ln3+ alone for 3 and 4). Single‐crystal XRD (SXRD) analysis revealed that 1 and 3 are isostructural to 2 and 4, respectively. TGA showed that the framework is thermally stable up to about 400 °C for 1 and 2, and about 450 °C for 3 and 4. PXRD analysis showed their pore‐structure distortions without noticeable framework–structure changes during drying processes. The shapes of gas sorption isotherms for 1 and 3 are almost identical to those for 2 and 4, respectively. Solvothermal immersion of 1 and 2 in Tb3+ and Eu3+ solutions resulted in the framework metal‐ion exchange affording 4 and 3, respectively, as confirmed by photoluminescence (PL), PXRD, IR, inductively coupled plasma atomic emission spectroscopy (ICP‐AES), and energy‐dispersive X‐ray (EDX) analyses. [ABSTRACT FROM AUTHOR]

A highly active and stable Fe3C-containing Fe/N/C catalyst, derived from a cationic Cd(ii)-based metal–organic framework involving accurate control over Fe-doping via anion-exchange with potassium ferricyanide, shows superior oxygen reduction performance over the benchmark Pt/C catalyst in an alkaline electrolyte. [ABSTRACT FROM AUTHOR]

Post-synthetic methods are considered facile and effective for adjusting a material's properties. This Frontiers article highlights recent advances in the post-synthetic modifications of MOF-74 type frameworks, whose high-density exposed metal sites, arranged along the chain direction, are grafted by various diamines with different lengths and structures, leading to the tuning of CO2 adsorption capabilities. [ABSTRACT FROM AUTHOR]

A three‐dimensional Cd2+ framework (1) with wide one‐dimensional hexagonal channels was prepared based on a tripodal tricarboxylate ligand possessing nitrogen donor atoms. The Cd atoms form a chain structure bridged by carboxylates and aqua ligands. Upon Mg2+ ion capture, the fluorescence emission of this porous material was 5.2 times greater than its Mg2+‐free fluorescence. To the best of our knowledge, such enhancement has not been previously reported for metal–organic framework sensory systems. The sensing performance of 1 is reversible over repeated cycles of Mg2+ inclusion and release, revealing the reusability of this material. In the presence of other tested metal ions, Mg2+ ions were selectively detected owing to the operation of this "turn‐on" mechanism. Thus, this platform is a promising sensor material for selective Mg2+ ion recognition. A three‐dimensional CdII framework with wide one‐dimensional channels exhibits sensitive, selective, reusable "turn‐on" sensing for Mg2+ over other tested metal ions. [ABSTRACT FROM AUTHOR]

Abstract: For real‐world postcombustion applications in the mitigation of CO2 emissions using dry sorbents, adsorption and desorption behaviors should be controlled to design and fabricate prospective materials with optimal CO2 performances. Herein, we prepared diamine‐functionalized Mg2(dobpdc) (H4dobpdc=4,4′‐dihydroxy‐(1,1′‐biphenyl)‐3,3′‐dicarboxylic acid). (1‐diamine) with ethylenediamine (en), primary–secondary (N‐ethylethylenediamine—een and N‐isopropylethylenediamine—ipen), primary–tertiary, and secondary–secondary diamines. A slight alteration of the number of alkyl substituents on the diamines and their alkyl chain length dictates the desorption temperature (Tdes) at 100 % CO2, desorption characteristics, and ΔT systematically to result in the tuning of the working capacity. The existence of bulky substituents on the diamines improves the framework stability upon exposure to O2, SO2, and water vapor, relevant to real flue‐gas conditions. Bulky substituents are also responsible for an interesting two‐step behavior observed for the ipen case, as revealed by DFT calculations. Among the diamine‐appended metal–organic frameworks, 1‐een, which has the required adsorption and desorption properties, is a promising material for sorbent‐based CO2 capture processes. Hence, CO2 performance and framework durability can be tailored by the judicial selection of the diamine structure, which enables property design at will and facilitates the development of desirable CO2‐capture materials. [ABSTRACT FROM AUTHOR]

With regard to fluorescence quenching commonly observed during metal-ion detection, 'turn-on' chemical sensing has been rarely reported, but could be extremely important because it facilitates the selective recognition of target objects of interest against a dark background. A metal-organic framework (MOF) chemosensor has been prepared that serves as an efficient platform for the selective detection of Cu2+ and Cd2+ ions over other metal ions. In particular, this framework shows the highest fluorescence enhancement (≈60-fold relative to Cd-free MOF) for the hazardous metal ion Cd2+ among luminescent MOFs and displays excellent reusability in repeated cycles. The direct diffusion of Cd2+ into the crystal pores has also been visualized for the first time. [ABSTRACT FROM AUTHOR]

A combined sonication and microwave irradiation procedure provides the most effective functionalization of ethylenediamine (en) and branched primary diamines of 1-methylethylenediamine (men) and 1,1-dimethylethylenediamine (den) onto the open metal sites of Mg2(dobpdc) ( 1). The CO2 capacities of the advanced adsorbents 1-en and 1-men under simulated flue gas conditions are 19 wt % and 17.4 wt %, respectively, which are the highest values reported among amine-functionalized metal-organic frameworks (MOFs) to date. Moreover, 1-den exhibits both a significant working capacity (12.2 wt %) and superb CO2 uptake (11 wt %) at 3 % CO2. Additionally, this framework showcases the superior recyclability; ultrahigh stability after exposure to O2, moisture, and SO2; and exceptional CO2 adsorption capacity under humid conditions, which are unprecedented among MOFs. We also elucidate that the performance of CO2 adsorption can be controlled by the structure of the diamine ligands grafted such as the number of amine end groups or the presence of side groups, which provides the first systematic and comprehensive demonstration of fine-tuning of CO2 uptake capability using different amines. [ABSTRACT FROM AUTHOR]

A series of metal-organic frameworks (MOFs) M2(dobpdc) (M=Mn, Co, Ni, Zn; H4dobpdc=4,4′-dihydroxy-1,1′-biphenyl-3,3′-dicarboxylic acid), with a highly dense arrangement of open metal sites along hexagonal channels were prepared by microwave-assisted or simple solvothermal reactions. The activated materials were structurally expanded when guest molecules including CO2 were introduced into the pores. The Lewis acidity of the open metal sites varied in the order MnZn, as confirmed by C=O stretching bands in the IR spectra, which are related to the CO2 adsorption enthalpy. DFT calculations revealed that the high CO2 binding affinity of transition-metal-based M2(dobpdc) is primarily attributable to the favorable charge transfer from CO2 (oxygen lone pair acting as a Lewis base) to the open metal sites (Lewis acid), while electrostatic effects, the underlying factor responsible for the particular order of binding strength observed across different transition metals, also play a role. The framework stability against water coincides with the order of Lewis acidity. In this series of MOFs, the structural stability of Ni2(dobpdc) is exceptional; it endured in water vapor, liquid water, and in refluxing water for one month, and the solid remained intact on exposure to solutions of pH 2-13. The DFT calculations also support the experimental finding that Ni2(dobpdc) has higher chemical stability than the other frameworks. [ABSTRACT FROM AUTHOR]

Facile postsynthetic oxidation of the thiol-laced UiO-66-type framework UiO-66(SH)2 enabled the generation of UiO-66(SO3H)2 with sulfonic acid groups covalently linked to the backbone of the system. The oxidized material exhibited a superprotonic conductivity of 8.4×10−2 S cm−1 at 80 °C and 90 % relative humidity, and long-term stability of the conductivity was observed. This level of conductivity exceeds that of any proton-conducting MOF reported to date and is equivalent to the conductivity of the most effective known electrolyte, Nafion. [ABSTRACT FROM AUTHOR]

A porous metal-organic framework (MOF), [Ni2(dobdc)(H2O)2]⋅6 H2O (Ni2(dobdc) or Ni-MOF-74; dobdc4−=2,5-dioxido-1,4-benzenedicarboxylate) with hexagonal channels was synthesized using a microwave-assisted solvothermal reaction. Soaking Ni2(dobdc) in sulfuric acid solutions at different pH values afforded new proton-conducting frameworks, H+@Ni2(dobdc). At pH 1.8, the acidified MOF shows proton conductivity of 2.2×10−2 S cm−1 at 80 °C and 95 % relative humidity (RH), approaching the highest values reported for MOFs. Proton conduction occurs via the Grotthuss mechanism with a significantly low activation energy as compared to other proton-conducting MOFs. Protonated water clusters within the pores of H+@Ni2(dobdc) play an important role in the conduction process. [ABSTRACT FROM AUTHOR]

Abstract: X-ray structural analysis shows that {[Cu 2(CTA) (H 2 O)]· 5 H 2 O} n constitutes infinite one-dimensional parallel chains along the c-axis with water columns running down the crystallographic a-axis. The inclusion of water molecules is reversible and is confirmed by X-ray powder diffraction studies. The magnetic data (2–300K) reveal that there are alternate ferro- (J =0.29cm−1) and antiferromagnetic (J =−2.5cm−1) interactions. [Copyright &y& Elsevier]

Innenrücktitelbild: High Ammonia Uptake of a Metal-Organic Framework Adsorbent in a Wide Pressure Range (Angew. Keywords: adsorption; ammonia capture; metal-organic frameworks; open metal sites; porosity EN adsorption ammonia capture metal-organic frameworks open metal sites porosity 22991 22991 1 12/18/20 20201207 NES 201207 B Poröse NH SB 3 sb -Adsorbentien b sind durch ungenügende NH SB 3 sb -Aufnahme, niedrige NH SB 3 sb -Affinitäten bei niedrigem Druck und geringe chemische Stabilität unter feuchten Bedingungen charakterisiert. Adsorption, ammonia capture, metal-organic frameworks, open metal sites, porosity. [Extracted from the article]

[Display omitted] • Recent progress on Xe/Kr adsorption and separation using MOF adsorbents was reviewed. • Innovative strategies to boost Xe/Kr separation in MOF materials have been disclosed. • The importance of advanced computational studies in Xe/Kr separation were described. • The promises, challenges and next steps in MOFs for Xe/Kr separation were presented. Xenon (Xe) and krypton (Kr) separation is of great interest and plays an essential role in the industry. However, the identical properties and ultra-low concentrations of Xe and Kr are the main challenges related with the separation. Compared with the conventionally used cryogenic process, porous materials-based physical adsorption is promising for efficient and cost-effective separation processes. Herein, this review targets on recent development in the design, synthesis, and Xe/Kr capture and separation performances of metal–organic frameworks (MOFs). We thoroughly evaluate and discuss innovative strategies to enhance Xe/Kr capture and separation in MOFs. Along with the discussions of strategies and developments in MOF, a brief discussion about the advances of computational studies was also provided. Finally, future challenges and prospects of MOFs for Xe/Kr capture and separation are highlighted. We believe that this review will effectively guide readers in the design and selection of suitable MOFs for Xe/Kr adsorption and separation in future endeavors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Naphthalene-based M 2 (dondc) series with open metal sites is prepared. • Ni 2 (dondc) achieves a second-highest volumetric H 2 storage capacity of 10.74 g/L. • The strong affinity of the open metal site to H 2 is confirmed in Ni 2 (dondc). • The long-term durability of Ni 2 (dondc) in H 2 storage is demonstrated. Adsorbent-based hydrogen storage systems offer a potential solution to current challenges in hydrogen storage, particularly those requiring high pressures or cryogenic temperatures. Specifically, the use of metal–organic frameworks (MOFs) featuring open metal sites that strongly adsorb hydrogen represents a promising strategy for near-ambient-temperature hydrogen storage. This study investigates the hydrogen storage properties of M 2 (dondc) (M = Mg2+, Co2+, and Ni2+), an extended version of MOF-74. Among this series, Ni 2 (dondc) exhibits the second-highest volumetric hydrogen capacity of 10.74 g L−1 at 298 K under pressure swing adsorption conditions (100 to 5 bar) at ambient temperatures. The superior hydrogen storage performance of Ni 2 (dondc) is attributed to its highly polarizable Ni open metal sites and a significant heat of adsorption of 12.2 kJ mol−1. These findings are corroborated by temperature-programmed desorption spectroscopy and van der Waals-corrected density functional theory calculations. In addition to its exceptional hydrogen capacity, Ni 2 (dondc) exhibits robust structural stability and long-term durability, positioning it as a promising candidate for near-ambient-temperature hydrogen storage applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • LiCl nanoparticle-embedded MOF composite, LiCl@Mg 2 (dobpdc)-5 , was prepared via wet impregnation method. • LiCl@Mg 2 (dobpdc)-5 exhibits the highest volumetric and gravimetric NH 3 capacities. • LiCl@Mg 2 (dobpdc)-5 shows negligible volume expansion after formation of LiCl(NH 3) 4. • This study presents a practical strategy for fostering progress in NH 3 storage systems for hydrogen carriers. Although porous adsorbents show potential for NH 3 capture and storage, practical issues such as stability and limited gravimetric/volumetric capacity persist. Lithium chloride (LiCl), which possesses the highest theoretical NH 3 capacity among metal halides, faces challenges such as a significantly high plateau pressure and inevitable volume expansion in the LiCl(NH 3) 4 complex, hindering static NH 3 storage. Herein, we introduce a series of M 2 (dobpdc)-based composites, specifically LiCl@Mg 2 (dobpdc)-5 , showcasing the highest gravimetric/volumetric NH 3 adsorption capacity (48.3 mmol g−1/65.8 mmol cm−3) and superior NH 3 storage density (1.12 g cm−3) at 298 K and 1 bar. Notably, the indirect gravimetric hydrogen storage capacity was calculated to be 14.6 wt%, which is comparable to the hydrogen storage capacity of NH 3 itself (17.8 wt%). This remarkable performance stems from the presence of LiCl in the metal nodes, highly dispersed LiCl nanoparticles (NPs), and open metal sites. Additionally, the composite avoids volume expansion even after LiCl(NH 3) 4 formation at 273 K. Thorough analysis using van der Waals-corrected density functional theory calculations confirmed the efficacy of the LiCl impregnation method, suggesting its potential to advance NH 3 storage systems for hydrogen carriers. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel method for coating of epn-Mg 2 (dobpdc)@SBS composites was developed. • The composites showed a significant CO 2 working capacity with full recyclability. • Facile, generally applicable coating route with the composite ink was demonstrated. • The coated materials exhibited excellent recycable working capacity. • Long-term durability under realistic indoor CO 2 conditions was obtained. Reducing the concentration of indoor carbon dioxide (CO 2) to an acceptable safe level of 1,000 ppm is an important issue because a high level of CO 2 in closed spaces causes lethargy and fatigue. Although diamine-functionalized metal–organic framework (MOF) adsorbents with high CO 2 capacities under indoor air conditions are available, the moisture-induced degradation of MOFs and their shaping remains a challenge for practical applications. Herein, we report the fabrication of epn-functionalized Mg 2 (dobpdc) composites, which proceeded by mixing with a polystyrene-block-polybutadiene-block-polystyrene (SBS) hydrophobic polymer (epn = 1-ethylpropane-1,3-diamine; dobpdc4− = 4,4′-dioxido-3,3′-biphenyldicarboxylate). The composites were successfully shaped in the form of membranes with different amounts of MOF (epn-MOFX@SBS; X = 60–80 wt%). Specifically, epn-MOF80@SBS exhibited a significant CO 2 adsorption of 2.8 mmol g−1 at 1,000 ppm with recyclable working capacity. The composites were further coated on the surfaces of different supports, such as a Ti mesh, an air filter, and granular activated carbon via a facile and simple spraying method. The experimental conditions were 1,000 ppm CO 2 and 60% relative humidity in a 50-L chamber; the coated materials displayed invariant CO 2 removal performances over 10 cycles and even after 7 days of exposure. The recyclable and long-term CO 2 adsorption capacities demonstrate that the MOF-polymer composites and their coating on various supports provide a useful and effective route for indoor CO 2 capture under realistic conditions. [ABSTRACT FROM AUTHOR]

A three-dimensional Zn(II) framework,[Zn4O(L)3(DMF)2]·0.5DMF·H2O (1; H2L = 3,3′-dimethoxybiphenyl-4,4′-dicarboxylicacid) was prepared under a solvothermal reaction in DMF. The structurereveals that the 3-fold interpenetration is stabilized in the frameworkwith a distinct secondary building unit of the formula [Zn4O(R-CO2)6(DMF)2], slightly differentfrom that of MOF-5. Phase transformations in 1occurreversibly via two pathways of solvent exchange/resolvation and activation/resolvation,which is indicative of the presence of extensive structural flexibility.Nitrobenzene among tested solvents is selectively detected by 1, and the sensing event was operating repeatedly. The three-dimensionalframework of 1with 3-fold interpenetration is uniquelyconverted to the two-dimensional Cu phase with no interpenetration,reflecting a drastic dimensionality variation. [ABSTRACT FROM AUTHOR]

[Display omitted] • We systematically categorized and described positional regioisomerism with multiple functional groups in MOF organic linkers. • Regioisomeric MOFs bearing two identical groups and two different groups were mainly discussed. • More than three dissimilar groups in MOFs were discussed in terms of their structures and functions. Metal-organic frameworks (MOFs) have been considered an emerging material for various applications. The fine tunability of both their inorganic nodes and organic ligands make MOFs a good platform for target-specific utilization. Generally, two coordinating groups (e.g., carboxylate) are necessary for MOF formations in case of representative, benzene-dicarboxylic acid type MOFs, and the additional functional groups could be installed in the remaining sites of organic ligands. Various functional groups could be introduced on the ligands such as amino-, halo-, hydroxy-, ether, thiol, and etc. In addition, multiple functional groups could be installed at specific position on the ligand by implementing positional regioisomerism, which helps elucidate the individual effects that each substituent imposes on the organic linkers. Therefore, deliberate structural and functional features can be introduced into a pristine framework. Indeed, this relatively ease functionalizations and positional isomerism of functional groups are the unique features of MOFs compare to other porous materials. In this review, we systematically categorized and described positional regioisomerism with multiple functional groups in MOF organic linkers. Specifically, regioisomeric MOFs bearing two identical groups, two different groups, more than three dissimilar groups, or miscellaneous moieties were discussed in terms of their structures and functions. A comprehensive overview of studies investigating the structures and properties triggered by the different positioning of functional groups in MOF frameworks could provide a base for the molecular design of desirable materials with advanced functionality. [ABSTRACT FROM AUTHOR]